Sample records for emitter therapy methods

  1. New Trends in Nuclear Data Research for Medical Applications

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Qaim, S. M.

    2005-05-24

    Nuclear methods play an important role in medicine, both in diagnosis and therapy. The status of nuclear data with regard to the production of commonly used diagnostic and therapeutic radionuclides is discussed. The new trends and data needs in the development of potentially useful radionuclides are outlined. They pertain to longer-lived positron emitters (e.g., 64Cu, 76Br, 124I) for studying slow metabolic processes, to positron emitters needed for quantification purposes (94mTc, 86Y, etc.) and to soft radiation emitting therapeutic radionuclides (103Pd, 186Re, 225Ac, etc.). The imaging problems with new positron emitters are discussed. As regards radiation therapy, data on the formationmore » of short-lived activation products in proton therapy are reported.« less

  2. New Trends in Nuclear Data Research for Medical Applications

    NASA Astrophysics Data System (ADS)

    Qaim, S. M.

    2005-05-01

    Nuclear methods play an important role in medicine, both in diagnosis and therapy. The status of nuclear data with regard to the production of commonly used diagnostic and therapeutic radionuclides is discussed. The new trends and data needs in the development of potentially useful radionuclides are outlined. They pertain to longer-lived positron emitters (e.g., 64Cu, 76Br, 124I) for studying slow metabolic processes, to positron emitters needed for quantification purposes (94mTc, 86Y, etc.) and to soft radiation emitting therapeutic radionuclides (103Pd, 186Re, 225Ac, etc.). The imaging problems with new positron emitters are discussed. As regards radiation therapy, data on the formation of short-lived activation products in proton therapy are reported.

  3. Cross section measurements for production of positron emitters for PET imaging in carbon therapy

    NASA Astrophysics Data System (ADS)

    Salvador, S.; Colin, J.; Cussol, D.; Divay, C.; Fontbonne, J.-M.; Labalme, M.

    2017-04-01

    In light ion beam therapy, positron (β+) emitters are produced by the tissue nuclei through nuclear interactions with the beam ions. They can be used for the verification of the delivered dose using positron emission tomography by comparing the spatial distribution of the β+ emitters activity to a computer simulation taking into account the patient morphology and the treatment plan. However, the accuracy of the simulation greatly depends on the method used to generate the nuclear interactions producing these emitters. In the case of Monte Carlo (MC) simulations, the nuclear interaction models still lack the required accuracy due to insufficient experimental cross section data. This is particularly true for carbon therapy where literature data on fragmentation cross sections of a carbon beam with targets of medical interest are very scarce. Therefore, we performed at GANIL in July 2016 measurements on β+ emitter production cross sections with a carbon beam at 25, 50, and 95 MeV/nucleon on thin targets (C, N, O, and PMMA). We extracted the production cross section of C,1110, 13N, and O,1514 that are essential to constrain or develop MC nuclear fragmentation models.

  4. Emittance matching of a slow extracted beam for a rotating gantry

    NASA Astrophysics Data System (ADS)

    Fujimoto, T.; Iwata, Y.; Matsuba, S.; Fujita, T.; Sato, S.; Shirai, T.; Noda, K.

    2017-09-01

    The introduction of a heavy-ion rotating gantry is in progress at the Heavy Ion Medical Accelerator in Chiba (HIMAC) for realizing high-precision cancer therapy using heavy ions. A scanning irradiation method will be applied to this gantry course with 48-430 MeV/u beam energy. In the rotating gantry, the horizontal and vertical beam parameters are coupled by its rotation. To maintain a circular spot shape at the isocenter irrespective of the gantry angle, achieving symmetric phase space distribution of the horizontal and vertical beam at the entrance of the rotating gantry is necessary. Therefore, compensating the horizontal and vertical emittance is necessary. We consider using a thin scatterer method to compensate the emittance. After considering the optical design for emittance matching, the scatterer device is located in the high-energy beam transport line. In the beam commissioning, we confirm that the symmetrical spot shape is obtained at the isocenter without depending on the gantry angle.

  5. Proton Therapy Verification with PET Imaging

    PubMed Central

    Zhu, Xuping; Fakhri, Georges El

    2013-01-01

    Proton therapy is very sensitive to uncertainties introduced during treatment planning and dose delivery. PET imaging of proton induced positron emitter distributions is the only practical approach for in vivo, in situ verification of proton therapy. This article reviews the current status of proton therapy verification with PET imaging. The different data detecting systems (in-beam, in-room and off-line PET), calculation methods for the prediction of proton induced PET activity distributions, and approaches for data evaluation are discussed. PMID:24312147

  6. An overview of targeted alpha therapy with 225Actinium and 213Bismuth.

    PubMed

    Morgenstern, Alfred; Apostolidis, Christos; Kratochwil, Clemens; Sathekge, Mike; Krolicki, Leszek; Bruchertseifer, Frank

    2018-05-01

    Recent reports of the remarkable therapeutic efficacy of 225Ac-labeled PSMA-617 for therapy of metastatic castration-resistant prostate cancer have underlined the clinical potential of targeted alpha therapy. This review describes methods for the production of 225Ac and its daughter nuclide 213Bi and summarizes the current clinical experience with both alpha emitters with particular focus on recent studies of targeted alpha therapy of bladder cancer, brain tumors, neuroendocrine tumors and prostate cancer. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  7. TPS(PET)-A TPS-based approach for in vivo dose verification with PET in proton therapy.

    PubMed

    Frey, K; Bauer, J; Unholtz, D; Kurz, C; Krämer, M; Bortfeld, T; Parodi, K

    2014-01-06

    Since the interest in ion-irradiation for tumour therapy has significantly increased over the last few decades, intensive investigations are performed to improve the accuracy of this form of patient treatment. One major goal is the development of methods for in vivo dose verification. In proton therapy, a PET (positron emission tomography)-based approach measuring the irradiation-induced tissue activation inside the patient has been already clinically implemented. The acquired PET images can be compared to an expectation, derived under the assumption of a correct treatment application, to validate the particle range and the lateral field position in vivo. In the context of this work, TPSPET is introduced as a new approach to predict proton-irradiation induced three-dimensional positron emitter distributions by means of the same algorithms of the clinical treatment planning system (TPS). In order to perform additional activity calculations, reaction-channel-dependent input positron emitter depth distributions are necessary, which are determined from the application of a modified filtering approach to the TPS reference depth dose profiles in water. This paper presents the implementation of TPSPET on the basis of the research treatment planning software treatment planning for particles. The results are validated in phantom and patient studies against Monte Carlo simulations, and compared to β(+)-emitter distributions obtained from a slightly modified version of the originally proposed one-dimensional filtering approach applied to three-dimensional dose distributions. In contrast to previously introduced methods, TPSPET provides a faster implementation, the results show no sensitivity to lateral field extension and the predicted β(+)-emitter densities are fully consistent to the planned treatment dose as they are calculated by the same pencil beam algorithms. These findings suggest a large potential of the application of TPSPET for in vivo dose verification in the daily clinical routine.

  8. A model for optimizing delivery of targeted radionuclide therapies into resection cavity margins for the treatment of primary brain cancers.

    PubMed

    Raghavan, Raghu; Howell, Roger W; Zalutsky, Michael R

    2017-06-01

    Radionuclides conjugated to molecules that bind specifically to cancer cells are of great interest as a means to increase the specificity of radiotherapy. Currently, the methods to disseminate these targeted radiotherapeutics have been either systemic delivery or by bolus injection into the tumor or tumor resection cavity. Herein we model a potentially more efficient method of delivery, namely pressure-driven fluid flow, called convection-enhanced delivery (CED), where a device infuses the molecules in solution (or suspension) directly into the tissue of interest. In particular, we focus on the setting of primary brain cancer after debulking surgery, where the tissue margins surrounding the surgical resection cavity are infiltrated with tumor cells and the most frequent sites of tumor recurrence. We develop the combination of fluid flow, chemical kinetics, and radiation dose models needed to examine such protocols. We focus on Auger electron-emitting radionuclides (e.g. 67 Ga, 77 Br, 111 In, 125 I, 123 I, 193m Pt, 195m Pt) whose short range makes them ideal for targeted therapy in this setting of small foci of tumor spread within normal tissue. By solving these model equations, we confirm that a CED protocol is promising in allowing sufficient absorbed dose to destroy cancer cells with minimal absorbed dose to normal cells at clinically feasible activity levels. We also show that Auger emitters are ideal for this purpose while the longer range alpha particle emitters fail to meet criteria for effective therapy (as neither would energetic beta particle emitters). The model is used with simplified assumptions on the geometry and homogeneity of brain tissue to allow semi-analytic solutions to be displayed, and with the purpose of a first examination of this new delivery protocol proposed for radionuclide therapy. However, we emphasize that it is immediately extensible to personalized therapy treatment planning as we have previously shown for conventional CED, at the price of requiring a fully numerical computerized approach.

  9. SYNCHROTRON RADIATION, FREE ELECTRON LASER, APPLICATION OF NUCLEAR TECHNOLOGY, ETC. Design of a multi-cusp ion source for proton therapy

    NASA Astrophysics Data System (ADS)

    Wu, Xiao-Bing; Huang, Tao; Ouyang, Hua-Fu; Zhang, Hua-Shun; Gong, Ke-Yun

    2010-12-01

    The permanent magnets of the discharge chamber in a multi-cusp proton source are studied and designed. The three electrode extraction system is adopted and simulated. A method to extract different amounts of current while keeping the beam emittance unchanged is proposed.

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

    NASA Astrophysics Data System (ADS)

    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.

  11. Radial arrays of nano-electrospray ionization emitters and methods of forming electrosprays

    DOEpatents

    Kelly, Ryan T [West Richland, WA; Tang, Keqi [Richland, WA; Smith, Richard D [Richland, WA

    2010-10-19

    Electrospray ionization emitter arrays, as well as methods for forming electrosprays, are described. The arrays are characterized by a radial configuration of three or more nano-electrospray ionization emitters without an extractor electrode. The methods are characterized by distributing fluid flow of the liquid sample among three or more nano-electrospray ionization emitters, forming an electrospray at outlets of the emitters without utilizing an extractor electrode, and directing the electrosprays into an entrance to a mass spectrometry device. Each of the nano-electrospray ionization emitters can have a discrete channel for fluid flow. The nano-electrospray ionization emitters are circularly arranged such that each is shielded substantially equally from an electrospray-inducing electric field.

  12. Targeted and Nontargeted α-Particle Therapies.

    PubMed

    McDevitt, Michael R; Sgouros, George; Sofou, Stavroula

    2018-06-04

    α-Particle irradiation of cancerous tissue is increasingly recognized as a potent therapeutic option. We briefly review the physics, radiobiology, and dosimetry of α-particle emitters, as well as the distinguishing features that make them unique for radiopharmaceutical therapy. We also review the emerging clinical role of α-particle therapy in managing cancer and recent studies on in vitro and preclinical α-particle therapy delivered by antibodies, other small molecules, and nanometer-sized particles. In addition to their unique radiopharmaceutical characteristics, the increased availability and improved radiochemistry of α-particle radionuclides have contributed to the growing recent interest in α-particle radiotherapy. Targeted therapy strategies have presented novel possibilities for the use of α-particles in the treatment of cancer. Clinical experience has already demonstrated the safe and effective use of α-particle emitters as potent tumor-selective drugs for the treatment of leukemia and metastatic disease.

  13. Targeted and Nontargeted α-Particle Therapies

    PubMed Central

    McDevitt, Michael R.; Sgouros, George; Sofou, Stavroula

    2018-01-01

    α-Particle irradiation of cancerous tissue is increasingly recognized as a potent therapeutic option. We briefly review the physics, radiobiology, and dosimetry of α-particle emitters, as well as the distinguishing features that make them unique for radiopharmaceutical therapy. We also review the emerging clinical role of α-particle therapy in managing cancer and recent studies on in vitro and preclinical α-particle therapy delivered by antibodies, other small molecules, and nanometer-sized particles. In addition to their unique radiopharmaceutical characteristics, the increased availability and improved radiochemistry of α-particle radionuclides have contributed to the growing recent interest in α-particle radiotherapy. Targeted therapy strategies have presented novel possibilities for the use of α-particles in the treatment of cancer. Clinical experience has already demonstrated the safe and effective use of α-particle emitters as potent tumor-selective drugs for the treatment of leukemia and metastatic disease. PMID:29345977

  14. Shielding in ungated field emitter arrays

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Harris, J. R.; Jensen, K. L.; Shiffler, D. A.

    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 bemore » 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.« less

  15. Emitter location errors in electronic recognition system

    NASA Astrophysics Data System (ADS)

    Matuszewski, Jan; Dikta, Anna

    2017-04-01

    The paper describes some of the problems associated with emitter location calculations. This aspect is the most important part of the series of tasks in the electronic recognition systems. The basic tasks include: detection of emission of electromagnetic signals, tracking (determining the direction of emitter sources), signal analysis in order to classify different emitter types and the identification of the sources of emission of the same type. The paper presents a brief description of the main methods of emitter localization and the basic mathematical formulae for calculating their location. The errors' estimation has been made to determine the emitter location for three different methods and different scenarios of emitters and direction finding (DF) sensors deployment in the electromagnetic environment. The emitter has been established using a special computer program. On the basis of extensive numerical calculations, the evaluation of precise emitter location in the recognition systems for different configuration alignment of bearing devices and emitter was conducted. The calculations which have been made based on the simulated data for different methods of location are presented in the figures and respective tables. The obtained results demonstrate that calculation of the precise emitter location depends on: the number of DF sensors, the distances between emitter and DF sensors, their mutual location in the reconnaissance area and bearing errors. The precise emitter location varies depending on the number of obtained bearings. The higher the number of bearings, the better the accuracy of calculated emitter location in spite of relatively high bearing errors for each DF sensor.

  16. Theranostics of prostate cancer: from molecular imaging to precision molecular radiotherapy targeting the prostate specific membrane antigen.

    PubMed

    Kulkarni, Harshad R; Singh, Aviral; Langbein, Thomas; Schuchardt, Christiane; Mueller, Dirk; Zhang, Jingjing; Lehmann, Coline; Baum, Richard P

    2018-06-01

    Alterations at the molecular level are a hallmark of cancer. Prostate cancer is associated with the overexpression of prostate-specific membrane antigen (PSMA) in a majority of cases, predominantly in advanced tumors, increasing with the grade or Gleason's score. PSMA can be selectively targeted using radiolabeled PSMA ligands. These small molecules binding the PSMA can be radiolabeled with γ-emitters like 99m Tc and 111 In or positron emitters like 68 Ga and 18 F for diagnosis as well as with their theranostic pairs such as 177 Lu (β-emitter) or 225 Ac (α-emitter) for therapy. This review summarizes the theranostic role of PSMA ligands for molecular imaging and targeted molecular radiotherapy, moving towards precision oncology.

  17. Treatment planning for internal emitter therapy: Methods, applications and clinical implications

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sgouros, G.

    1999-01-01

    Treatment planning involves three basic steps: (1) a procedure must be devised that will provide the most relevant information, (2) the procedure must be applied and (3) the resulting information must be translated into a definition of the optimum implementation. There are varying degrees of treatment planning that may be implemented in internal emitter therapy. As in chemotherapy, the information from a Phase 1 study may be used to treat patients based upon body surface area. If treatment planning is included on a patient-specific basis, a pretherapy, trace-labeled, administration of the radiopharmaceutical is generally required. The data collected following themore » tracer dose may range from time-activity curves of blood and whole-body for use in blood, marrow or total body absorbed dose estimation to patient imaging for three-dimensional internal emitter dosimetry. The most ambitious approach requires a three-dimensional set of images representing radionuclide distribution (SPECT or PET) and a corresponding set of images representing anatomy (CT or MRI). The absorbed dose (or dose-rate) distribution may be obtained by convolution of a point kernel with the radioactivity distribution or by direct Monte Carlo calculation. A critical requirement for both techniques is the development of an overall structure that makes it possible, in a routine manner, to input the images, to identify the structures of interest and to display the results of the dose calculations in a clinically relevant manner. 52 refs., 4 figs., 1 tab.« less

  18. Method of manufacturing a hybrid emitter all back contact solar cell

    DOEpatents

    Loscutoff, Paul; Rim, Seung

    2017-02-07

    A method of manufacturing an all back contact solar cell which 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. A second emitter of the solar cell is formed in the single crystalline silicon substrate and is made of doped single crystalline silicon. The method further includes forming contact holes that allow metal contacts to connect to corresponding emitters.

  19. Method for photon activation positron annihilation analysis

    DOEpatents

    Akers, Douglas W.

    2006-06-06

    A non-destructive testing method comprises providing a specimen having at least one positron emitter therein; determining a threshold energy for activating the positron emitter; and determining whether a half-life of the positron emitter is less than a selected half-life. If the half-life of the positron emitter is greater than or equal to the selected half-life, then activating the positron emitter by bombarding the specimen with photons having energies greater than the threshold energy and detecting gamma rays produced by annihilation of positrons in the specimen. If the half-life of the positron emitter is less then the selected half-life, then alternately activating the positron emitter by bombarding the specimen with photons having energies greater then the threshold energy and detecting gamma rays produced by positron annihilation within the specimen.

  20. Physical and engineering aspect of carbon beam therapy

    NASA Astrophysics Data System (ADS)

    Kanai, Tatsuaki; Kanematsu, Nobuyuki; Minohara, Shinichi; Yusa, Ken; Urakabe, Eriko; Mizuno, Hideyuki; Iseki, Yasushi; Kanazawa, Mitsutaka; Kitagawa, Atsushi; Tomitani, Takehiro

    2003-08-01

    Conformal irradiation system of HIMAC has been up-graded for a clinical trial using a technique of a layer-stacking method. The system has been developed for localizing irradiation dose to target volume more effectively than the present irradiation dose. With dynamic control of the beam modifying devices, a pair of wobbler magnets, and multileaf collimator and range shifter, during the irradiation, more conformal radiotherapy can be achieved. The system, which has to be adequately safe for patient irradiations, was constructed and tested from a viewpoint of safety and the quality of the dose localization realized. A secondary beam line has been constructed for use of radioactive beam in heavy-ion radiotherapy. Spot scanning method has been adapted for the beam delivery system of the radioactive beam. Dose distributions of the spot beam were measured and analyzed taking into account of aberration of the beam optics. Distributions of the stopped positron-emitter beam can be observed by PET. Pencil beam of the positron-emitter, about 1 mm size, can also be used for measurements ranges of the test beam in patients using positron camera. The positron camera, consisting of a pair of Anger-type scintillation detectors, has been developed for this verification before treatment. Wash-out effect of the positron-emitter was examined using the positron camera installed. In this report, present status of the HIMAC irradiation system is described in detail.

  1. Accelerator-based neutron source for boron neutron capture therapy (BNCT) and method

    DOEpatents

    Yoon, W.Y.; Jones, J.L.; Nigg, D.W.; Harker, Y.D.

    1999-05-11

    A source for boron neutron capture therapy (BNCT) comprises a body of photoneutron emitter that includes heavy water and is closely surrounded in heat-imparting relationship by target material; one or more electron linear accelerators for supplying electron radiation having energy of substantially 2 to 10 MeV and for impinging such radiation on the target material, whereby photoneutrons are produced and heat is absorbed from the target material by the body of photoneutron emitter. The heavy water is circulated through a cooling arrangement to remove heat. A tank, desirably cylindrical or spherical, contains the heavy water, and a desired number of the electron accelerators circumferentially surround the tank and the target material as preferably made up of thin plates of metallic tungsten. Neutrons generated within the tank are passed through a surrounding region containing neutron filtering and moderating materials and through neutron delimiting structure to produce a beam or beams of epithermal neutrons normally having a minimum flux intensity level of 1.0{times}10{sup 9} neutrons per square centimeter per second. Such beam or beams of epithermal neutrons are passed through gamma ray attenuating material to provide the required epithermal neutrons for BNCT use. 3 figs.

  2. Accelerator-based neutron source for boron neutron capture therapy (BNCT) and method

    DOEpatents

    Yoon, Woo Y.; Jones, James L.; Nigg, David W.; Harker, Yale D.

    1999-01-01

    A source for boron neutron capture therapy (BNCT) comprises a body of photoneutron emitter that includes heavy water and is closely surrounded in heat-imparting relationship by target material; one or more electron linear accelerators for supplying electron radiation having energy of substantially 2 to 10 MeV and for impinging such radiation on the target material, whereby photoneutrons are produced and heat is absorbed from the target material by the body of photoneutron emitter. The heavy water is circulated through a cooling arrangement to remove heat. A tank, desirably cylindrical or spherical, contains the heavy water, and a desired number of the electron accelerators circumferentially surround the tank and the target material as preferably made up of thin plates of metallic tungsten. Neutrons generated within the tank are passed through a surrounding region containing neutron filtering and moderating materials and through neutron delimiting structure to produce a beam or beams of epithermal neutrons normally having a minimum flux intensity level of 1.0.times.10.sup.9 neutrons per square centimeter per second. Such beam or beams of epithermal neutrons are passed through gamma ray attenuating material to provide the required epithermal neutrons for BNCT use.

  3. Asymmetrical field emitter

    DOEpatents

    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.

  4. Method and apparatus for multispray emitter for mass spectrometry

    DOEpatents

    Smith, Richard D.; Tang, Keqi; Lin, Yuehe

    2004-12-14

    A method and apparatus that utilizes two or more emitters simultaneously to form an electrospray of a sample that is then directed into a mass spectrometer, thereby increasing the total ion current introduced into an electrospray ionization mass spectrometer, given a liquid flow rate of a sample. The method and apparatus are most conveniently constructed as an array of spray emitters fabricated on a single chip, however, the present invention encompasses any apparatus wherein two or more emitters are simultaneously utilized to form an electrospray of a sample that is then directed into a mass spectrometer.

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

    NASA Astrophysics Data System (ADS)

    Greffrath, Fabian; Prieler, Robert; Telle, Rainer

    2014-11-01

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

  6. Analysis of induced electrical currents from magnetic field coupling inside implantable neurostimulator leads

    PubMed Central

    2011-01-01

    Background Over the last decade, the number of neurostimulator systems implanted in patients has been rapidly growing. Nearly 50, 000 neurostimulators are implanted worldwide annually. The most common type of implantable neurostimulators is indicated for pain relief. At the same time, commercial use of other electromagnetic technologies is expanding, making electromagnetic interference (EMI) of neurostimulator function an issue of concern. Typically reported sources of neurostimulator EMI include security systems, metal detectors and wireless equipment. When near such sources, patients with implanted neurostimulators have reported adverse events such as shock, pain, and increased stimulation. In recent in vitro studies, radio frequency identification (RFID) technology has been shown to inhibit the stimulation pulse of an implantable neurostimulator system during low frequency exposure at close distances. This could potentially be due to induced electrical currents inside the implantable neurostimulator leads that are caused by magnetic field coupling from the low frequency identification system. Methods To systematically address the concerns posed by EMI, we developed a test platform to assess the interference from coupled magnetic fields on implantable neurostimulator systems. To measure interference, we recorded the output of one implantable neurostimulator, programmed for best therapy threshold settings, when in close proximity to an operating low frequency RFID emitter. The output contained electrical potentials from the neurostimulator system and those induced by EMI from the RFID emitter. We also recorded the output of the same neurostimulator system programmed for best therapy threshold settings without RFID interference. Using the Spatially Extended Nonlinear Node (SENN) model, we compared threshold factors of spinal cord fiber excitation for both recorded outputs. Results The electric current induced by low frequency RFID emitter was not significant to have a noticeable effect on electrical stimulation. Conclusions We demonstrated a method for analyzing effects of coupled magnetic field interference on implantable neurostimulator system and its electrodes which could be used by device manufacturers during the design and testing phases of the development process. PMID:22014169

  7. Superresolution microscope image reconstruction by spatiotemporal object decomposition and association: application in resolving t-tubule structure in skeletal muscle

    PubMed Central

    Sun, Mingzhai; Huang, Jiaqing; Bunyak, Filiz; Gumpper, Kristyn; De, Gejing; Sermersheim, Matthew; Liu, George; Lin, Pei-Hui; Palaniappan, Kannappan; Ma, Jianjie

    2014-01-01

    One key factor that limits resolution of single-molecule superresolution microscopy relates to the localization accuracy of the activated emitters, which is usually deteriorated by two factors. One originates from the background noise due to out-of-focus signals, sample auto-fluorescence, and camera acquisition noise; and the other is due to the low photon count of emitters at a single frame. With fast acquisition rate, the activated emitters can last multiple frames before they transiently switch off or permanently bleach. Effectively incorporating the temporal information of these emitters is critical to improve the spatial resolution. However, majority of the existing reconstruction algorithms locate the emitters frame by frame, discarding or underusing the temporal information. Here we present a new image reconstruction algorithm based on tracklets, short trajectories of the same objects. We improve the localization accuracy by associating the same emitters from multiple frames to form tracklets and by aggregating signals to enhance the signal to noise ratio. We also introduce a weighted mean-shift algorithm (WMS) to automatically detect the number of modes (emitters) in overlapping regions of tracklets so that not only well-separated single emitters but also individual emitters within multi-emitter groups can be identified and tracked. In combination with a maximum likelihood estimator method (MLE), we are able to resolve low to medium density of overlapping emitters with improved localization accuracy. We evaluate the performance of our method with both synthetic and experimental data, and show that the tracklet-based reconstruction is superior in localization accuracy, particularly for weak signals embedded in a strong background. Using this method, for the first time, we resolve the transverse tubule structure of the mammalian skeletal muscle. PMID:24921337

  8. Superresolution microscope image reconstruction by spatiotemporal object decomposition and association: application in resolving t-tubule structure in skeletal muscle.

    PubMed

    Sun, Mingzhai; Huang, Jiaqing; Bunyak, Filiz; Gumpper, Kristyn; De, Gejing; Sermersheim, Matthew; Liu, George; Lin, Pei-Hui; Palaniappan, Kannappan; Ma, Jianjie

    2014-05-19

    One key factor that limits resolution of single-molecule superresolution microscopy relates to the localization accuracy of the activated emitters, which is usually deteriorated by two factors. One originates from the background noise due to out-of-focus signals, sample auto-fluorescence, and camera acquisition noise; and the other is due to the low photon count of emitters at a single frame. With fast acquisition rate, the activated emitters can last multiple frames before they transiently switch off or permanently bleach. Effectively incorporating the temporal information of these emitters is critical to improve the spatial resolution. However, majority of the existing reconstruction algorithms locate the emitters frame by frame, discarding or underusing the temporal information. Here we present a new image reconstruction algorithm based on tracklets, short trajectories of the same objects. We improve the localization accuracy by associating the same emitters from multiple frames to form tracklets and by aggregating signals to enhance the signal to noise ratio. We also introduce a weighted mean-shift algorithm (WMS) to automatically detect the number of modes (emitters) in overlapping regions of tracklets so that not only well-separated single emitters but also individual emitters within multi-emitter groups can be identified and tracked. In combination with a maximum likelihood estimator method (MLE), we are able to resolve low to medium density of overlapping emitters with improved localization accuracy. We evaluate the performance of our method with both synthetic and experimental data, and show that the tracklet-based reconstruction is superior in localization accuracy, particularly for weak signals embedded in a strong background. Using this method, for the first time, we resolve the transverse tubule structure of the mammalian skeletal muscle.

  9. Diamond/diamond-like carbon coated nanotube structures for efficient electron field emission

    NASA Technical Reports Server (NTRS)

    Dimitrijevic, Steven (Inventor); Withers, James C. (Inventor); Loutfy, Raouf O. (Inventor)

    2005-01-01

    The present invention is directed to a nanotube coated with diamond or diamond-like carbon, a field emitter cathode comprising same, and a field emitter comprising the cathode. It is also directed to a method of preventing the evaporation of carbon from a field emitter comprising a cathode comprised of nanotubes by coating the nanotube with diamond or diamond-like carbon. In another aspect, the present invention is directed to a method of preventing the evaporation of carbon from an electron field emitter comprising a cathode comprised of nanotubes, which method comprises coating the nanotubes with diamond or diamond-like carbon.

  10. Radiolabeling of Nanoparticles and Polymers for PET Imaging

    PubMed Central

    Stockhofe, Katharina; Postema, Johannes M.; Schieferstein, Hanno; Ross, Tobias L.

    2014-01-01

    Nanomedicine has become an emerging field in imaging and therapy of malignancies. Nanodimensional drug delivery systems have already been used in the clinic, as carriers for sensitive chemotherapeutics or highly toxic substances. In addition, those nanodimensional structures are further able to carry and deliver radionuclides. In the development process, non-invasive imaging by means of positron emission tomography (PET) represents an ideal tool for investigations of pharmacological profiles and to find the optimal nanodimensional architecture of the aimed-at drug delivery system. Furthermore, in a personalized therapy approach, molecular imaging modalities are essential for patient screening/selection and monitoring. Hence, labeling methods for potential drug delivery systems are an indispensable need to provide the radiolabeled analog. In this review, we describe and discuss various approaches and methods for the labeling of potential drug delivery systems using positron emitters. PMID:24699244

  11. Spectrally-engineered solar thermal photovoltaic devices

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lenert, Andrej; Bierman, David; Chan, Walker

    A solar thermal photovoltaic device, and method of forming same, includes a solar absorber and a spectrally selective emitter formed on either side of a thermally conductive substrate. The solar absorber is configured to absorb incident solar radiation. The solar absorber and the spectrally selective emitter are configured with an optimized emitter-to-absorber area ratio. The solar thermal photovoltaic device also includes a photovoltaic cell in thermal communication with the spectrally selective emitter. The spectrally selective emitter is configured to permit high emittance for energies above a bandgap of the photovoltaic cell and configured to permit low emittance for energies belowmore » the bandgap.« less

  12. A multiple-scattering polaritonic-operator method for hybrid arrays of metal nanoparticles and quantum emitters

    NASA Astrophysics Data System (ADS)

    Chatzidakis, Georgios D.; Yannopapas, Vassilios

    2018-05-01

    We present a new technique for the study of hybrid collections of quantum emitters (atoms, molecules, quantum dots) with nanoparticles. The technique is based on a multiple-scattering polaritonic-operator formalism in conjunction with an electromagnetic coupled dipole method. Apart from collections of quantum emitters and nanoparticles, the method can equally treat the interaction of a collection of quantum emitters with a single nano-object of arbitrary shape in which case the nano-object is treated as a finite three-dimensional lattice of point scatterers. We have applied our method to the case of linear array (chain) of dimers of quantum emitters and metallic nanoparticles wherein the corresponding (geometrical and physical) parameters of the dimers are chosen so as the interaction between the emitter and the nanoparticle lies in the strong-coupling regime in order to enable the formation of plexciton states in the dimer. In particular, for a linear chain of dimers, we show that the corresponding light spectra reveal a multitude of plexciton modes resulting from the hybridization of the plexciton resonances of each individual dimer in a manner similar to the tight-binding description of electrons in solids.

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

    PubMed

    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.

  14. A simulation study of a dual-plate in-room PET system for dose verification in carbon ion therapy

    NASA Astrophysics Data System (ADS)

    Chen, Ze; Hu, Zheng-Guo; Chen, Jin-Da; Zhang, Xiu-Ling; Guo, Zhong-Yan; Xiao, Guo-Qing; Sun, Zhi-Yu; Huang, Wen-Xue; Wang, Jian-Song

    2014-08-01

    During carbon ion therapy, lots of positron emitters such as 11C, 15O, 10C are generated in irradiated tissues by nuclear reactions, and can be used to track the carbon beam in the tissue by a positron emission tomography (PET) scanner. In this study, an dual-plate in-room PET scanner has been designed and evaluated based on the GATE simulation platform to monitor patient dose in carbon ion therapy. The dual-plate PET is designed to avoid interference with the carbon beamline and with patient positioning. Its performance was compared with that of four-head and full-ring PET scanners. The dual-plate, four-head and full-ring PET scanners consisted of 30, 60, 60 detector modules, respectively, with a 36 cm distance between directly opposite detector modules for dose deposition measurements. Each detector module consisted of a 24×24 array of 2 mm×2 mm×18 mm LYSO pixels coupled to a Hamamatsu H8500 PMT. To estimate the production yield of positron emitters, a 10 cm×15 cm×15 cm cuboid PMMA phantom was irradiated with 172, 200, 250 MeV/u 12C beams. 3D images of the activity distribution measured by the three types of scanner are produced by an iterative reconstruction algorithm. By comparing the longitudinal profile of positron emitters along the carbon beam path, it is indicated that use of the dual-plate PET scanner is feasible for monitoring the dose distribution in carbon ion therapy.

  15. Portable emittance measurement device

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liakin, D.; Seleznev, D.; Orlov, A.

    2010-02-15

    In Institute for Theoretical and Experimental Physics (ITEP) the portable emittance measurements device is developed. It provides emittance measurements both with ''pepper-pot'' and ''two slits'' methods. Depending on the method of measurements, either slits or pepper-pot mask with scintillator are mounted on the two activators and are installed in two standard Balzer's cross chamber with CF-100 flanges. To match the angle resolution for measured beam, the length of the stainless steel pipe between two crosses changes is adjusted. The description of the device and results of emittance measurements at the ITEP ion source test bench are presented.

  16. Investigations of the emittance and brightness of ion beams from an electron beam ion source of the Dresden EBIS type.

    PubMed

    Silze, Alexandra; Ritter, Erik; Zschornack, Günter; Schwan, Andreas; Ullmann, Falk

    2010-02-01

    We have characterized ion beams extracted from the Dresden EBIS-A, a compact room-temperature electron beam ion source (EBIS) with a permanent magnet system for electron beam compression, using a pepper-pot emittance meter. The EBIS-A is the precursor to the Dresden EBIS-SC in which the permanent magnets have been replaced by superconducting solenoids for the use of the source in high-ion-current applications such as heavy-ion cancer therapy. Beam emittance and brightness values were calculated from data sets acquired for a variety of source parameters, in leaky as well as pulsed ion extraction mode. With box shaped pulses of C(4+) ions at an energy of 39 keV root mean square emittances of 1-4 mm mrad and a brightness of 10 nA mm(-2) mrad(-2) were achieved. The results meet the expectations for high quality ion beams generated by an electron beam ion source.

  17. Improvement of pain and disability in elderly patients with degenerative osteoarthritis of the knee treated with narrow-band light therapy.

    PubMed

    Stelian, J; Gil, I; Habot, B; Rosenthal, M; Abramovici, I; Kutok, N; Khahil, A

    1992-01-01

    To evaluate the effects of low-power light therapy on pain and disability in elderly patients with degenerative osteoarthritis of the knee. Partially double-blinded, fully randomized trial comparing red, infrared, and placebo light emitters. Fifty patients with degenerative osteoarthritis of both knees were randomly assigned to three treatment groups: red (15 patients), infrared (18 patients), and placebo (17 patients). Infrared and placebo emitters were double-blinded. Self-applied treatment to both sides of the knee for 15 minutes twice a day for 10 days. Short-Form McGill Pain Questionnaire, Present Pain Intensity, and Visual Analogue Scale for pain and Disability Index Questionnaire for disability were used. We evaluated pain and disability before and on the tenth day of therapy. The period from the end of the treatment until the patient's request to be retreated was summed up 1 year after the trial. Pain and disability before treatment did not show statistically significant differences between the three groups. Pain reduction in the red and infrared groups after the treatment was more than 50% in all scoring methods (P less than 0.05). There was no significant pain improvement in the placebo group. We observed significant functional improvement in red- and infrared-treated groups (p less than 0.05), but not in the placebo group. The period from the end of treatment until the patients required treatment was longer for red and infrared groups than for the placebo group (4.2 +/- 3.0, 6.1 +/- 3.2, and 0.53 +/- 0.62 months, for red, infrared, and placebo, respectively). Low-power light therapy is effective in relieving pain and disability in degenerative osteoarthritis of the knee.

  18. Photonically engineered incandescent emitter

    DOEpatents

    Gee, James M.; Lin, Shawn-Yu; Fleming, James G.; Moreno, James B.

    2003-08-26

    A photonically engineered incandescence is disclosed. The emitter materials and photonic crystal structure can be chosen to modify or suppress thermal radiation above a cutoff wavelength, causing the emitter to selectively emit in the visible and near-infrared portions of the spectrum. An efficient incandescent lamp is enabled thereby. A method for fabricating a three-dimensional photonic crystal of a structural material, suitable for the incandescent emitter, is also disclosed.

  19. Photonically Engineered Incandescent Emitter

    DOEpatents

    Gee, James M.; Lin, Shawn-Yu; Fleming, James G.; Moreno, James B.

    2005-03-22

    A photonically engineered incandescence is disclosed. The emitter materials and photonic crystal structure can be chosen to modify or suppress thermal radiation above a cutoff wavelength, causing the emitter to selectively emit in the visible and near-infrared portions of the spectrum. An efficient incandescent lamp is enabled thereby. A method for fabricating a three-dimensional photonic crystal of a structural material, suitable for the incandescent emitter, is also disclosed.

  20. Minimum emittance in TBA and MBA lattices

    NASA Astrophysics Data System (ADS)

    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.

  1. Multi-ball and one-ball geolocation and location verification

    NASA Astrophysics Data System (ADS)

    Nelson, D. J.; Townsend, J. L.

    2017-05-01

    We present analysis methods that may be used to geolocate emitters using one or more moving receivers. While some of the methods we present may apply to a broader class of signals, our primary interest is locating and tracking ships from short pulsed transmissions, such as the maritime Automatic Identification System (AIS.) The AIS signal is difficult to process and track since the pulse duration is only 25 milliseconds, and the pulses may only be transmitted every six to ten seconds. Several fundamental problems are addressed, including demodulation of AIS/GMSK signals, verification of the emitter location, accurate frequency and delay estimation and identification of pulse trains from the same emitter. In particular, we present several new correlation methods, including cross-cross correlation that greatly improves correlation accuracy over conventional methods and cross- TDOA and cross-FDOA functions that make it possible to estimate time and frequency delay without the need of computing a two dimensional cross-ambiguity surface. By isolating pulses from the same emitter and accurately tracking the received signal frequency, we are able to accurately estimate the emitter location from the received Doppler characteristics.

  2. Radioligand therapy of metastatic castration-resistant prostate cancer: current approaches.

    PubMed

    Awang, Zool Hilmi; Essler, Markus; Ahmadzadehfar, Hojjat

    2018-05-23

    Prostate Cancer is the forth most common type of cancer. Prostate-specific membrane antigen (PSMA) is anchored in the cell membrane of prostate epithelial cells. PSMA is highly expressed on prostate epithelial cells and strongly up-regulated in prostate cancer. Therefore it is an appropriate target for diagnostic and therapy of prostate cancer and its metastases. This article discusses several articles on radionuclide treatments in prostate cancer and the results on PSMA therapy with either beta or alpha emitters as a salvage therapy.

  3. Field emission electron source

    DOEpatents

    Zettl, Alexander Karlwalter; Cohen, Marvin Lou

    2000-01-01

    A novel field emitter material, field emission electron source, and commercially feasible fabrication method is described. The inventive field emission electron source produces reliable electron currents of up to 400 mA/cm.sup.2 at 200 volts. The emitter is robust and the current it produces is not sensitive to variability of vacuum or the distance between the emitter tip and the cathode. The novel emitter has a sharp turn-on near 100 volts.

  4. Low emittance electron storage rings

    NASA Astrophysics Data System (ADS)

    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.

  5. Processing of materials for uniform field emission

    DOEpatents

    Pam, L.S.; Felter, T.E.; Talin, A.; Ohlberg, D.; Fox, C.; Han, S.

    1999-01-12

    This method produces a field emitter material having a uniform electron emitting surface and a low turn-on voltage. Field emitter materials having uniform electron emitting surfaces as large as 1 square meter and turn-on voltages as low as 16V/{micro}m can be produced from films of electron emitting materials such as polycrystalline diamond, diamond-like carbon, graphite and amorphous carbon by the method of the present invention. The process involves conditioning the surface of a field emitter material by applying an electric field to the surface, preferably by scanning the surface of the field emitter material with an electrode maintained at a fixed distance of at least 3 {micro}m above the surface of the field emitter material and at a voltage of at least 500V. In order to enhance the uniformity of electron emission the step of conditioning can be preceded by ion implanting carbon, nitrogen, argon, oxygen or hydrogen into the surface layers of the field emitter material. 2 figs.

  6. Processing of materials for uniform field emission

    DOEpatents

    Pam, Lawrence S.; Felter, Thomas E.; Talin, Alec; Ohlberg, Douglas; Fox, Ciaran; Han, Sung

    1999-01-01

    This method produces a field emitter material having a uniform electron emitting surface and a low turn-on voltage. Field emitter materials having uniform electron emitting surfaces as large as 1 square meter and turn-on voltages as low as 16V/.mu.m can be produced from films of electron emitting materials such as polycrystalline diamond, diamond-like carbon, graphite and amorphous carbon by the method of the present invention. The process involves conditioning the surface of a field emitter material by applying an electric field to the surface, preferably by scanning the surface of the field emitter material with an electrode maintained at a fixed distance of at least 3 .mu.m above the surface of the field emitter material and at a voltage of at least 500V. In order to enhance the uniformity of electron emission the step of conditioning can be preceeded by ion implanting carbon, nitrogen, argon, oxygen or hydrogen into the surface layers of the field emitter material.

  7. Systems and Methods for Implementing Robust Carbon Nanotube-Based Field Emitters

    NASA Technical Reports Server (NTRS)

    Kristof, Valerie (Inventor); Manohara, Harish (Inventor); Toda, Risaku (Inventor)

    2015-01-01

    Systems and methods in accordance with embodiments of the invention implement carbon nanotube-based field emitters. In one embodiment, a method of fabricating a carbon nanotube field emitter includes: patterning a substrate with a catalyst, where the substrate has thereon disposed a diffusion barrier layer; growing a plurality of carbon nanotubes on at least a portion of the patterned catalyst; and heating the substrate to an extent where it begins to soften such that at least a portion of at least one carbon nanotube becomes enveloped by the softened substrate.

  8. A simulation study of a C-shaped in-beam PET system for dose verification in carbon ion therapy

    NASA Astrophysics Data System (ADS)

    Jung An, Su; Beak, Cheol-Ha; Lee, Kisung; Hyun Chung, Yong

    2013-01-01

    The application of hadrons such as carbon ions is being developed for the treatment of cancer. The effectiveness of such a technique is due to the eligibility of charged particles in delivering most of their energy near the end of the range, called the Bragg peak. However, accurate verification of dose delivery is required since misalignment of the hadron beam can cause serious damage to normal tissue. PET scanners can be utilized to track the carbon beam to the tumor by imaging the trail of the hadron-induced positron emitters in the irradiated volume. In this study, we designed and evaluated (through Monte Carlo simulations) an in-beam PET scanner for monitoring patient dose in carbon beam therapy. A C-shaped PET and a partial-ring PET were designed to avoid interference between the PET detectors and the therapeutic carbon beam delivery. Their performance was compared with that of a full-ring PET scanner. The C-shaped, partial-ring, and full-ring scanners consisted of 14, 12, and 16 detector modules, respectively, with a 30.2 cm inner diameter for brain imaging. Each detector module was composed of a 13×13 array of 4.0 mm×4.0 mm×20.0 mm LYSO crystals and four round 25.4 mm diameter PMTs. To estimate the production yield of positron emitters such as 10C, 11C, and 15O, a cylindrical PMMA phantom (diameter, 20 cm; thickness, 20 cm) was irradiated with 170, 290, and 350 AMeV 12C beams using the GATE code. Phantom images of the three types of scanner were evaluated by comparing the longitudinal profile of the positron emitters, measured along the carbon beam as it passed a simulated positron emitter distribution. The results demonstrated that the development of a C-shaped PET scanner to characterize carbon dose distribution for therapy planning is feasible.

  9. Auger Emitting Radiopharmaceuticals for Cancer Therapy

    NASA Astrophysics Data System (ADS)

    Falzone, Nadia; Cornelissen, Bart; Vallis, Katherine A.

    Radionuclides that emit Auger electrons have been of particular interest as therapeutic agents. This is primarily due to the short range in tissue, controlled linear paths and high linear energy transfer of these particles. Taking into consideration that ionizations are clustered within several cubic nanometers around the point of decay the possibility of incorporating an Auger emitter in close proximity to the cancer cell DNA has immense therapeutic potential thus making nuclear targeted Auger-electron emitters ideal for precise targeting of cancer cells. Furthermore, many Auger-electron emitters also emit γ-radiation, this property makes Auger emitting radionuclides a very attractive option as therapeutic and diagnostic agents in the molecular imaging and management of tumors. The first requirement for the delivery of Auger emitting nuclides is the definition of suitable tumor-selective delivery vehicles to avoid normal tissue toxicity. One of the main challenges of targeted radionuclide therapy remains in matching the physical and chemical characteristics of the radionuclide and targeting moiety with the clinical character of the tumor. Molecules and molecular targets that have been used in the past can be classified according to the carrier molecule used to deliver the Auger-electron-emitting radionuclide. These include (1) antibodies, (2) peptides, (3) small molecules, (4) oligonucleotides and peptide nucleic acids (PNAs), (5) proteins, and (6) nanoparticles. The efficacy of targeted radionuclide therapy depends greatly on the ability to increase intranuclear incorporation of the radiopharmaceutical without compromising toxicity. Several strategies to achieve this goal have been proposed in literature. The possibility of transferring tumor therapy based on the emission of Auger electrons from experimental models to patients has vast therapeutic potential, and remains a field of intense research.

  10. THE MONITORING OF EFFLUENT FOR ALPHA EMITTERS. PART II. METHODS FOR THE DETERMINATION OF URANIUM, POLONIUM AND OTHER ALPHA EMITTERS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Smales, A.A.; Airey, L.; Woodward, J.

    1950-06-01

    Consideration has been given to the problem of separating and estimating uranium, polonium, and other alpha emitters (in order to provide analytical methods for their routine determination in conformily with the draft agreement on the Harwell effluent). Uranium may be ether extracted from solutions of ammonium nitrate as salting out agent at pHl with an efficiency of 98 to 99%. The deposition of polonium on silver foil is a specific method for this element and under prescribed conditions similar extraction efficiencies may be obtained. An adequate separation from all other alpha emitters'' is obtained and methods for the estimation ofmore » these are discussed. A comprehensive scheme involving a preliminary activity concentration step has been elaborated. Uranium, polonium, and the majority of the other alpha emitters'' are precipitated as their tannin complexes at pH8 using calcium hydroxide, the calcium-tannin complex acting as a carrier. That part of the activity remaining in solution is determined as in the total activity method, previously described. From the solution of the precipitate, polonium is first separated by electrodeposition, and then uranium by ether extraction in the presence of ammonium nitrate. The majority of the other alpha emitters'' still in the aqueous ammonium nitrate solution are collected on a second calcium-tannin precipitate, while the small part remaining in solution after this operation is obtained by direct evaporation. (auth)« less

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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. Design and testing a high fuel volume fraction, externally finned, thermionic emitter.

    NASA Technical Reports Server (NTRS)

    Peelgren, M. L.; Ernst, D. M.

    1971-01-01

    A prototypical, high fuel volume fraction, thermionic emitter body was designed and tested. The emitter body is all tungsten, with a 1.40-cm ID, a 3.23-cm OD, and eight full-length axial fins. The emitter thickness is 0.15 cm while the fins and outer clad are 0.075 cm thick. Different methods of fabrication were used in making the test samples. Stress analysis was performed with a three-dimensional elastic code. Thermal testing of the samples, duplicating calculated radial temperature gradients, heatup and cooldown rates, and emitter body temperatures in operation, was performed with no structural failures noted (six heatup and cooldown cycles per sample). Further emitter analysis and testing is planned.

  14. Analysis of induced electrical currents from magnetic field coupling inside implantable neurostimulator leads.

    PubMed

    Pantchenko, Oxana S; Seidman, Seth J; Guag, Joshua W

    2011-10-21

    Over the last decade, the number of neurostimulator systems implanted in patients has been rapidly growing. Nearly 50, 000 neurostimulators are implanted worldwide annually. The most common type of implantable neurostimulators is indicated for pain relief. At the same time, commercial use of other electromagnetic technologies is expanding, making electromagnetic interference (EMI) of neurostimulator function an issue of concern. Typically reported sources of neurostimulator EMI include security systems, metal detectors and wireless equipment. When near such sources, patients with implanted neurostimulators have reported adverse events such as shock, pain, and increased stimulation. In recent in vitro studies, radio frequency identification (RFID) technology has been shown to inhibit the stimulation pulse of an implantable neurostimulator system during low frequency exposure at close distances. This could potentially be due to induced electrical currents inside the implantable neurostimulator leads that are caused by magnetic field coupling from the low frequency identification system. To systematically address the concerns posed by EMI, we developed a test platform to assess the interference from coupled magnetic fields on implantable neurostimulator systems. To measure interference, we recorded the output of one implantable neurostimulator, programmed for best therapy threshold settings, when in close proximity to an operating low frequency RFID emitter. The output contained electrical potentials from the neurostimulator system and those induced by EMI from the RFID emitter. We also recorded the output of the same neurostimulator system programmed for best therapy threshold settings without RFID interference. Using the Spatially Extended Nonlinear Node (SENN) model, we compared threshold factors of spinal cord fiber excitation for both recorded outputs. The electric current induced by low frequency RFID emitter was not significant to have a noticeable effect on electrical stimulation. We demonstrated a method for analyzing effects of coupled magnetic field interference on implantable neurostimulator system and its electrodes which could be used by device manufacturers during the design and testing phases of the development process.

  15. Emittance measurements of the CLIO electron beam

    NASA Astrophysics Data System (ADS)

    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.

  16. A nephron-based model of the kidneys for macro-to-micro α-particle dosimetry

    NASA Astrophysics Data System (ADS)

    Hobbs, Robert F.; Song, Hong; Huso, David L.; Sundel, Margaret H.; Sgouros, George

    2012-07-01

    Targeted α-particle therapy is a promising treatment modality for cancer. Due to the short path-length of α-particles, the potential efficacy and toxicity of these agents is best evaluated by microscale dosimetry calculations instead of whole-organ, absorbed fraction-based dosimetry. Yet time-integrated activity (TIA), the necessary input for dosimetry, can still only be quantified reliably at the organ or macroscopic level. We describe a nephron- and cellular-based kidney dosimetry model for α-particle radiopharmaceutical therapy, more suited to the short range and high linear energy transfer of α-particle emitters, which takes as input kidney or cortex TIA and through a macro to micro model-based methodology assigns TIA to micro-level kidney substructures. We apply a geometrical model to provide nephron-level S-values for a range of isotopes allowing for pre-clinical and clinical applications according to the medical internal radiation dosimetry (MIRD) schema. We assume that the relationship between whole-organ TIA and TIA apportioned to microscale substructures as measured in an appropriate pre-clinical mammalian model also applies to the human. In both, the pre-clinical and the human model, microscale substructures are described as a collection of simple geometrical shapes akin to those used in the Cristy-Eckerman phantoms for normal organs. Anatomical parameters are taken from the literature for a human model, while murine parameters are measured ex vivo. The murine histological slides also provide the data for volume of occupancy of the different compartments of the nephron in the kidney: glomerulus versus proximal tubule versus distal tubule. Monte Carlo simulations are run with activity placed in the different nephron compartments for several α-particle emitters currently under investigation in radiopharmaceutical therapy. The S-values were calculated for the α-emitters and their descendants between the different nephron compartments for both the human and murine models. The renal cortex and medulla S-values were also calculated and the results compared to traditional absorbed fraction calculations. The nephron model enables a more optimal implementation of treatment and is a critical step in understanding toxicity for human translation of targeted α-particle therapy. The S-values established here will enable a MIRD-type application of α-particle dosimetry for α-emitters, i.e. measuring the TIA in the kidney (or renal cortex) will provide meaningful and accurate nephron-level dosimetry.

  17. Method of forming emitters for a back-contact solar cell

    DOEpatents

    Li, Bo; Cousins, Peter J.; Smith, David D.

    2015-09-29

    Methods of forming emitters for back-contact solar cells are described. In one embodiment, a method includes forming a first solid-state dopant source above a substrate. The first solid-state dopant source includes a plurality of regions separated by gaps. Regions of a second solid-state dopant source are formed above the substrate by printing.

  18. Method of forming emitters for a back-contact solar cell

    DOEpatents

    Li, Bo; Cousins, Peter J; Smith, David D

    2014-12-16

    Methods of forming emitters for back-contact solar cells are described. In one embodiment, a method includes forming a first solid-state dopant source above a substrate. The first solid-state dopant source includes a plurality of regions separated by gaps. Regions of a second solid-state dopant source are formed above the substrate by printing.

  19. Method or forming emitters for a back-contact solar cell

    DOEpatents

    Li, Bo; Cousins, Peter J.; Smith, David D.

    2014-08-12

    Methods of forming emitters for back-contact solar cells are described. In one embodiment, a method includes forming a first solid-state dopant source above a substrate. The first solid-state dopant source includes a plurality of regions separated by gaps. Regions of a second solid-state dopant source are formed above the substrate by printing.

  20. Evaluation of a standard test method for total hemispherical emittance of surfaces from 293K to 1673K

    NASA Technical Reports Server (NTRS)

    Compton, E. C.

    1986-01-01

    Emittance tests were made on samples of Rene' 41, Haynes 188, and Inconel 625 superalloy metals in an evaluation of a standard test method for determining total hemispherical emittances of surfaces from 293 K to 1673 K. The intent of this evaluation was to address any problems encountered, check repeatability of measured emittances, and gain experience in use of the test procedure. Five test specimens were fabricated to prescribe test dimensions and surfaces cleaned of oil and residue. Three of these specimens were without oxidized surfaces and two with oxidized surfaces. The oxidized specimens were Rene' 41 and Haynes 188. The tests were conducted in a vacuum where the samples were resistance-heated to various temperature levels ranging from 503 K to 1293 K. The calculated results for emittance, in the worst case, were repeatable to a maximum spread to + or - 4% from the mean of five sets of plotted data for each specimen.

  1. Silicon cells made by self-aligned selective-emitter plasma-etchback process

    DOEpatents

    Ruby, Douglas S.; Schubert, William K.; Gee, James M.; Zaidi, Saleem H.

    2000-01-01

    Photovoltaic cells and methods for making them are disclosed wherein the metallized grids of the cells are used to mask portions of cell emitter regions to allow selective etching of phosphorus-doped emitter regions. The preferred etchant is SF.sub.6 or a combination of SF.sub.6 and O.sub.2. This self-aligned selective etching allows for enhanced blue response (versus cells with uniform heavy doping of the emitter) while preserving heavier doping in the region beneath the gridlines needed for low contact resistance. Embodiments are disclosed for making cells with or without textured surfaces. Optional steps include plasma hydrogenation and PECVD nitride deposition, each of which are suited to customized applications for requirements of given cells to be manufactured. The techniques disclosed could replace expensive and difficult alignment methodologies used to obtain selectively etched emitters, and they may be easily integrated with existing plasma processing methods and techniques of the invention may be accomplished in a single plasma-processing chamber.

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

    NASA Astrophysics Data System (ADS)

    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. New format presentation for infrared spectral emittance data. Infrared spectrometry studies, phase 5

    NASA Technical Reports Server (NTRS)

    Lyon, R. J. P.; Green, A. A.

    1972-01-01

    Methods for infrared radiance measurements from geological materials were studied for airborne use over terrains with minimal vegetation. The tasks of the investigation were: (1) calculation of emittance ratios, (2) comparison of IR spectral emittance data with K-band scatterometer data over Pisgah Crater, and (3) standard infrared spectral file. Published papers reporting the research are included.

  4. Plasmon-Assisted Selective and Super-Resolving Excitation of Individual Quantum Emitters on a Metal Nanowire.

    PubMed

    Li, Qiang; Pan, Deng; Wei, Hong; Xu, Hongxing

    2018-03-14

    Hybrid systems composed of multiple quantum emitters coupled with plasmonic waveguides are promising building blocks for future integrated quantum nanophotonic circuits. The techniques that can super-resolve and selectively excite contiguous quantum emitters in a diffraction-limited area are of great importance for studying the plasmon-mediated interaction between quantum emitters and manipulating the single plasmon generation and propagation in plasmonic circuits. Here we show that multiple quantum dots coupled with a silver nanowire can be controllably excited by tuning the interference field of surface plasmons on the nanowire. Because of the period of the interference pattern is much smaller than the diffraction limit, we demonstrate the selective excitation of two quantum dots separated by a distance as short as 100 nm. We also numerically demonstrate a new kind of super-resolution imaging method that combines the tunable surface plasmon interference pattern on the NW with the structured illumination microscopy technique. Our work provides a novel high-resolution optical excitation and imaging method for the coupled systems of multiple quantum emitters and plasmonic waveguides, which adds a new tool for studying and manipulating single quantum emitters and single plasmons for quantum plasmonic circuitry applications.

  5. Single photon emission from plasma treated 2D hexagonal boron nitride.

    PubMed

    Xu, Zai-Quan; Elbadawi, Christopher; Tran, Toan Trong; Kianinia, Mehran; Li, Xiuling; Liu, Daobin; Hoffman, Timothy B; Nguyen, Minh; Kim, Sejeong; Edgar, James H; Wu, Xiaojun; Song, Li; Ali, Sajid; Ford, Mike; Toth, Milos; Aharonovich, Igor

    2018-05-03

    Artificial atomic systems in solids are becoming increasingly important building blocks in quantum information processing and scalable quantum nanophotonic networks. Amongst numerous candidates, 2D hexagonal boron nitride has recently emerged as a promising platform hosting single photon emitters. Here, we report a number of robust plasma and thermal annealing methods for fabrication of emitters in tape-exfoliated hexagonal boron nitride (hBN) crystals. A two-step process comprising Ar plasma etching and subsequent annealing in Ar is highly robust, and yields an eight-fold increase in the concentration of emitters in hBN. The initial plasma-etching step generates emitters that suffer from blinking and bleaching, whereas the two-step process yields emitters that are photostable at room temperature with emission wavelengths greater than ∼700 nm. Density functional theory modeling suggests that the emitters might be associated with defect complexes that contain oxygen. This is further confirmed by generating the emitters via annealing hBN in air. Our findings advance the present understanding of the structure of quantum emitters in hBN and enhance the nanofabrication toolkit needed to realize integrated quantum nanophotonic circuits.

  6. Chromatic energy filter and characterization of laser-accelerated proton beams for particle therapy

    NASA Astrophysics Data System (ADS)

    Hofmann, Ingo; Meyer-ter-Vehn, Jürgen; Yan, Xueqing; Al-Omari, Husam

    2012-07-01

    The application of laser accelerated protons or ions for particle therapy has to cope with relatively large energy and angular spreads as well as possibly significant random fluctuations. We suggest a method for combined focusing and energy selection, which is an effective alternative to the commonly considered dispersive energy selection by magnetic dipoles. Our method is based on the chromatic effect of a magnetic solenoid (or any other energy dependent focusing device) in combination with an aperture to select a certain energy width defined by the aperture radius. It is applied to an initial 6D phase space distribution of protons following the simulation output from a Radiation Pressure Acceleration model. Analytical formula for the selection aperture and chromatic emittance are confirmed by simulation results using the TRACEWIN code. The energy selection is supported by properly placed scattering targets to remove the imprint of the chromatic effect on the beam and to enable well-controlled and shot-to-shot reproducible energy and transverse density profiles.

  7. Cascaded injection resonator for coherent beam combining of laser arrays

    DOEpatents

    Kireev, Vassili [Sunnyvale, CA; Liu, Yun; Protopopescu, Vladimir [Knoxville, TN; Braiman, Yehuda [Oak Ridge, TN

    2008-10-21

    The invention provides a cascaded injection resonator for coherent beam combining of laser arrays. The resonator comprises a plurality of laser emitters arranged along at least one plane and a beam sampler for reflecting at least a portion of each laser beam that impinges on the beam sampler, the portion of each laser beam from one of the laser emitters being reflected back to another one of the laser emitters to cause a beam to be generated from the other one of the laser emitters to the beam reflector. The beam sampler also transmits a portion of each laser beam to produce a laser output beam such that a plurality of laser output beams of the same frequency are produced. An injection laser beam is directed to a first laser emitter to begin a process of generating and reflecting a laser beam from one laser emitter to another laser emitter in the plurality. A method of practicing the invention is also disclosed.

  8. Planar-focusing cathodes.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lewellen, J. W.; Noonan, J.; Accelerator Systems Division

    2005-01-01

    Conventional {pi}-mode rf photoinjectors typically use magnetic solenoids for emittance compensation. This provides independent focusing strength but can complicate rf power feed placement, introduce asymmetries (due to coil crossovers), and greatly increase the cost of the photoinjector. Cathode-region focusing can also provide for a form of emittance compensation. Typically this method strongly couples focusing strength to the field gradient on the cathode, however, and usually requires altering the longitudinal position of the cathode to change the focusing. We propose a new method for achieving cathode-region variable-strength focusing for emittance compensation. The new method reduces the coupling to the gradient onmore » the cathode and does not require a change in the longitudinal position of the cathode. Expected performance for an S-band system is similar to conventional solenoid-based designs. This paper presents the results of rf cavity and beam dynamics simulations of the new design. We have proposed a method for performing emittance compensation using a cathode-region focusing scheme. This technique allows the focusing strength to be adjusted somewhat independently of the on-axis field strength. Beam dynamics calculations indicate performance should be comparable to presently in-use emittance compensation schemes, with a simpler configuration and fewer possibilities for emittance degradation due to the focusing optics. There are several potential difficulties with this approach, including cathode material selection, cathode heating, and peak fields in the gun. We hope to begin experimenting with a cathode of this type in the near future, and several possibilities exist for reducing the peak gradients to more acceptable levels.« less

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Optical properties of hybrid spherical nanoclusters containing quantum emitters and metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Yannopapas, V.; Paspalakis, E.

    2018-05-01

    We study theoretically the optical response of a hybrid spherical cluster containing quantum emitters and metallic nanoparticles. The quantum emitters are modeled as two-level quantum systems whose dielectric function is obtained via a density matrix approach wherein the modified spontaneous emission decay rate at the position of each quantum emitter is calculated via the electromagnetic Green's tensor. The problem of light scattering off the hybrid cluster is solved by employing the coupled-dipole method. We find, in particular, that the presence of the quantum emitters in the cluster, even in small fractions, can significantly alter the absorption and extinction spectra of the sole cluster of the metallic nanoparticles, where the corresponding electromagnetic modes can have a weak plexcitonic character under suitable conditions.

  11. A retractable electron emitter for the creation of unperturbed pure electron plasmas.

    PubMed

    Berkery, John W; Pedersen, Thomas Sunn; Sampedro, Luis

    2007-01-01

    A retractable electron emitter has been constructed for the creation of unperturbed pure electron plasmas on magnetic surfaces in the Columbia Non-neutral Torus stellarator. The previous method of electron emission using emitters mounted on stationary rods limited the confinement time to 20 ms. A pneumatically driven system that can retract from the magnetic axis to the last closed flux surface in less than 20 ms while filling the surfaces with electrons was designed. The motion of the retractable emitter was modeled with a system of dynamical equations. The measured position versus time of the emitter agrees well with the model and the fastest axis-to-edge retraction was measured to be 20 ms with 40 psig helium gas driving the pneumatic piston.

  12. Direct Observation of Ultralow Vertical Emittance using a Vertical Undulator

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wootton, Kent

    2015-09-17

    In recent work, the first quantitative measurements of electron beam vertical emittance using a vertical undulator were presented, with particular emphasis given to ultralow vertical emittances [K. P. Wootton, et al., Phys. Rev. ST Accel. Beams, 17, 112802 (2014)]. Using this apparatus, a geometric vertical emittance of 0.9 ± 0.3 pm rad has been observed. A critical analysis is given of measurement approaches that were attempted, with particular emphasis on systematic and statistical uncertainties. The method used is explained, compared to other techniques and the applicability of these results to other scenarios discussed.

  13. Remote detection of single emitters via optical waveguides

    NASA Astrophysics Data System (ADS)

    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.

  14. Process for reducing beta activity in uranium

    DOEpatents

    Briggs, Gifford G.; Kato, Takeo R.; Schonegg, Edward

    1986-10-07

    This invention is a method for lowering the beta radiation hazards associated with the casting of uranium. The method reduces the beta radiation emitted from the as-cast surfaces of uranium ingots. The method also reduces the amount of beta radiation emitters retained on the interiors of the crucibles that have been used to melt the uranium charges and which have undergone cleaning in a remote handling facility. The lowering of the radioactivity is done by scavenging the beta emitters from the molten uranium with a molten mixture containing the fluorides of magnesium and calcium. The method provides a means of collection and disposal of the beta emitters in a manner that reduces radiation exposure to operating personnel in the work area where the ingots are cast and processed.

  15. Process for reducing beta activity in uranium

    DOEpatents

    Briggs, Gifford G.; Kato, Takeo R.; Schonegg, Edward

    1986-01-01

    This invention is a method for lowering the beta radiation hazards associated with the casting of uranium. The method reduces the beta radiation emitted from the as-cast surfaces of uranium ingots. The method also reduces the amount of beta radiation emitters retained on the interiors of the crucibles that have been used to melt the uranium charges and which have undergone cleaning in a remote handling facility. The lowering of the radioactivity is done by scavenging the beta emitters from the molten uranium with a molten mixture containing the fluorides of magnesium and calcium. The method provides a means of collection and disposal of the beta emitters in a manner that reduces radiation exposure to operating personnel in the work area where the ingots are cast and processed.

  16. Process for reducing beta activity in uranium

    DOEpatents

    Briggs, G.G.; Kato, T.R.; Schonegg, E.

    1985-04-11

    This invention is a method for lowering the beta radiation hazards associated with the casting of uranium. The method reduces the beta radiation emitted from the as-cast surfaces of uranium ingots. The method also reduces the amount of beta radiation emitters retained on the interiors of the crucibles that have been used to melt the uranium charges and which undergone cleaning in a remote handling facility. The lowering of the radioactivity is done by scavenging the beta emitters from the molten uranium with a molten mixture containing the fluorides of magnesium and calcium. The method provides a means of collection and disposal of the beta emitters in a manner that reduces radiation exposure to operating personnel in the work area where the ingots are cast and processed. 5 tabs.

  17. Improvements for extending the time between maintenance periods for the Heidelberg ion beam therapy center (HIT) ion sources.

    PubMed

    Winkelmann, Tim; Cee, Rainer; Haberer, Thomas; Naas, Bernd; Peters, Andreas; Schreiner, Jochen

    2014-02-01

    The clinical operation at the Heidelberg Ion Beam Therapy Center (HIT) started in November 2009; since then more than 1600 patients have been treated. In a 24/7 operation scheme two 14.5 GHz electron cyclotron resonance ion sources are routinely used to produce protons and carbon ions. The modification of the low energy beam transport line and the integration of a third ion source into the therapy facility will be shown. In the last year we implemented a new extraction system at all three sources to enhance the lifetime of extraction parts and reduce preventive and corrective maintenance. The new four-electrode-design provides electron suppression as well as lower beam emittance. Unwanted beam sputtering effects which typically lead to contamination of the insulator ceramics and subsequent high-voltage break-downs are minimized by the beam guidance of the new extraction system. By this measure the service interval can be increased significantly. As a side effect, the beam emittance can be reduced allowing a less challenging working point for the ion sources without reducing the effective beam performance. This paper gives also an outlook to further enhancements at the HIT ion source testbench.

  18. Proton therapy treatment monitoring with the DoPET system: activity range, positron emitters evaluation and comparison with Monte Carlo predictions

    NASA Astrophysics Data System (ADS)

    Muraro, S.; Battistoni, G.; Belcari, N.; Bisogni, M. G.; Camarlinghi, N.; Cristoforetti, L.; Del Guerra, A.; Ferrari, A.; Fracchiolla, F.; Morrocchi, M.; Righetto, R.; Sala, P.; Schwarz, M.; Sportelli, G.; Topi, A.; Rosso, V.

    2017-12-01

    Ion beam irradiations can deliver conformal dose distributions minimizing damage to healthy tissues thanks to their characteristic dose profiles. Nevertheless, the location of the Bragg peak can be affected by different sources of range uncertainties: a critical issue is the treatment verification. During the treatment delivery, nuclear interactions between the ions and the irradiated tissues generate β+ emitters: the detection of this activity signal can be used to perform the treatment monitoring if an expected activity distribution is available for comparison. Monte Carlo (MC) codes are widely used in the particle therapy community to evaluate the radiation transport and interaction with matter. In this work, FLUKA MC code was used to simulate the experimental conditions of irradiations performed at the Proton Therapy Center in Trento (IT). Several mono-energetic pencil beams were delivered on phantoms mimicking human tissues. The activity signals were acquired with a PET system (DoPET) based on two planar heads, and designed to be installed along the beam line to acquire data also during the irradiation. Different acquisitions are analyzed and compared with the MC predictions, with a special focus on validating the PET detectors response for activity range verification.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Theoretical and experimental emittance measurements for a thin liquid sheet flow

    NASA Technical Reports Server (NTRS)

    Englehart, Amy N.; Mcconley, Marc W.; Chubb, Donald L.

    1995-01-01

    Surface tension forces at the edges of a thin liquid (approximately 200 microns) sheet flow result in a triangularly shaped sheet. Such a geometry is ideal for an external flow radiator. Since the fluid must have very low vapor pressure, Dow Corning 705 silicone oil was used and the emittance of a flowing sheet of oil was determined by two methods. The emittance was derived as a function of the temperature drop between the top of the sheet and the coalescence point of the sheet, the sink temperature, the volumetric flow and the length of the sheet. the emittance for the oil was also calculated using an extinction coefficient determined from spectral transmittance data of the oil. The oil's emittance ranges from .67 to .87 depending on the sheet thickness and sheet temperature. The emittance derived from the temperature drop was slightly less than the emittance calculated from transmittance data. An investigation of temperature fluctuation upstream of the slit plate was also done. The fluctuations were determined to be negligible, not affecting the temperature drop which was due to radiation.

  1. HOPI: on-line injection optimization program

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    LeMaire, J L

    1977-10-26

    A method of matching the beam from the 200 MeV linac to the AGS without the necessity of making emittance measurements is presented. An on-line computer program written on the PDP10 computer performs the matching by modifying independently the horizontal and vertical emittance. Experimental results show success with this method, which can be applied to any matching section.

  2. Emilio G. Segrè - Patents

    Science.gov Websites

    neutrons to thermal energies. US 2,573,069 METHOD AND APPARATUS FOR MEASURING STRONG ALPHA EMITTERS - Segrà ¨, E. G.; October 30, 1951 (to the U.S. Atomic Energy Commission) This patent describes an apparatus and method for the determination of the strength of a strong alpha emitter. The apparatus is so

  3. Ground Motion Studies for Large Future Accelerator

    NASA Astrophysics Data System (ADS)

    Takeda, Shigeru; Oide, Katsunobu

    1997-05-01

    The future large accelerator, such as TeV linear collider, should have extremely small emittance to perform the required luminosity. Precise alignment of machine components is essential to prevent emittance dilution. The ground motion spoils alignment of accelerator elements and results in emittance growth. The ground motion in the frequency range of seismic vibration is mostly coherent in the related accelerator. But the incoherent diffusive or Brownian like motion becomes dominant at frequency region less than seismic vibration [1, 2, 3]. Slow ground motion with respect to the machine performance is discussed including the method of tunnel construction. Our experimental results and recent excavated results clarify that application of TBMs is better excavating method than NATM (Drill + Blast) for accelerator tunnel to prevent emittance dilution. ([1] V. Shiltsev, Proc. of IWAA95 Tsukuba, 1995. [2] Shigeru Takeda et al., Proc. of EPAC96, 1996. [3] A. Sery, Proc. of LINAC96, 1996.)

  4. FUSION WELDING METHOD AND APPARATUS

    DOEpatents

    Wyman, W.L.; Steinkamp, W.I.

    1961-01-17

    An apparatus for the fusion welding of metal pieces at a joint is described. The apparatus comprises a highvacuum chamber enclosing the metal pieces and a thermionic filament emitter. Sufficient power is applied to the emitter so that when the electron emission therefrom is focused on the joint it has sufficient energy to melt the metal pieces, ionize the metallic vapor abcve the molten metal, and establish an arc discharge between the joint and the emitter.

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

    PubMed

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

    2014-02-14

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. A system for online beam emittance measurements and proton beam characterization

    NASA Astrophysics Data System (ADS)

    Nesteruk, K. P.; Auger, M.; Braccini, S.; Carzaniga, T. S.; Ereditato, A.; Scampoli, P.

    2018-01-01

    A system for online measurement of the transverse beam emittance was developed. It is named 4PrOBεaM (4-Profiler Online Beam Emittance Measurement) and was conceived to measure the emittance in a fast and efficient way using the multiple beam profiler method. The core of the system is constituted by four consecutive UniBEaM profilers, which are based on silica fibers passing across the beam. The 4PrOBεaM system was deployed for characterization studies of the 18 MeV proton beam produced by the IBA Cyclone 18 MeV cyclotron at Bern University Hospital (Inselspital). The machine serves daily radioisotope production and multi-disciplinary research, which is carried out with a specifically conceived Beam Transport Line (BTL). The transverse RMS beam emittance of the cyclotron was measured as a function of several machine parameters, such as the magnetic field, RF peak voltage, and azimuthal angle of the stripper. The beam emittance was also measured using the method based on the quadrupole strength variation. The results obtained with both techniques were compared and a good agreement was found. In order to characterize the longitudinal dynamics, the proton energy distribution was measured. For this purpose, a method was developed based on aluminum absorbers of different thicknesses, a UniBEaM detector, and a Faraday cup. The results were an input for a simulation of the BTL developed in the MAD-X software. This tool allows machine parameters to be tuned online and the beam characteristics to be optimized for specific applications.

  8. Theory and measurements of emittance preservation in plasma wakefield acceleration

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Frederico, Joel

    2016-12-01

    In this dissertation, we examine the preservation and measurement of emittance in the plasma wakefield acceleration blowout regime. Plasma wakefield acceleration (PWFA) is a revolutionary approach to accelerating charged particles that has been demonstrated to have the potential for gradients orders of magnitude greater than traditional approaches. The application of PWFA to the design of a linear collider will make new high energy physics research possible, but the design parameters must first be shown to be competitive with traditional methods. Emittance preservation is necessary in the design of a linear collider in order to maximize luminosity. We examine the conditionsmore » necessary for circular symmetry in the PWFA blowout regime, and demonstrate that current proposals meet these bounds. We also present an application of beam lamentation which describes the process of beam parameter and emittance matching. We show that the emittance growth saturates as a consequence of energy spread in the beam. The initial beam parameters determine the amount of emittance growth, while the contribution of energy spread is negligible. We also present a model for ion motion in the presence of a beam that is much more dense than the plasma. By combining the model of ion motion and emittance growth, we find the emittance growth due to ion motion is minimal in the case of marginal ion motion. In addition, we present a simulation that validates the ion motion model, which is under further development to examine emittance growth of both marginal and pronounced ion motion. Finally, we present a proof-of-concept of an emittance measurement which may enable the analysis of emittance preservation in future PWFA experiments.« less

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

    NASA Astrophysics Data System (ADS)

    Chen, Teng; 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.

  10. Microscale Digital Vacuum Electronic Gates

    NASA Technical Reports Server (NTRS)

    Manohara, Harish (Inventor); Mojarradi, Mohammed M. (Inventor)

    2014-01-01

    Systems and methods in accordance with embodiments of the invention implement microscale digital vacuum electronic gates. In one embodiment, a microscale digital vacuum electronic gate includes: a microscale field emitter that can emit electrons and that is a microscale cathode; and a microscale anode; where the microscale field emitter and the microscale anode are disposed within at least a partial vacuum; where the microscale field emitter and the microscale anode are separated by a gap; and where the potential difference between the microscale field emitter and the microscale anode is controllable such that the flow of electrons between the microscale field emitter and the microscale anode is thereby controllable; where when the microscale anode receives a flow of electrons, a first logic state is defined; and where when the microscale anode does not receive a flow of electrons, a second logic state is defined.

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

    NASA Astrophysics Data System (ADS)

    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.

  12. An accurate two-dimensional LBIC solution for bipolar transistors

    NASA Astrophysics Data System (ADS)

    Benarab, A.; Baudrand, H.; Lescure, M.; Boucher, J.

    1988-05-01

    A complete solution of the diffusion problem of carriers generated by a located light beam in the emitter and base region of a bipolar structure is presented. Green's function method and moment method are used to solve the 2-D diffusion equation in these regions. From the Green's functions solution of these equations, the light beam induced currents (LBIC) in the different junctions of the structure due to an extended generation represented by a rectangular light spot; are thus decided. The equations of these currents depend both on the parameters which characterise the structure, surface states, dimensions of the emitter and the base region, and the characteristics of the light spot, that is to say, the width and the wavelength. Curves illustrating the variation of the various LBIC in the base region junctions as a function of the impact point of the light beam ( x0) for different values of these parameters are discussed. In particular, the study of the base-emitter currents when the light beam is swept right across the sample illustrates clearly a good geometrical definition of the emitter region up to base end of the emitter-base space-charge areas and a "whirl" lateral diffusion beneath this region, (i.e. the diffusion of the generated carriers near the surface towards the horizontal base-emitter junction and those created beneath this junction towards the lateral (B-E) junctions).

  13. Instantaneous electron beam emittance measurement system based on the optical transition radiation principle

    NASA Astrophysics Data System (ADS)

    Jiang, Xiao-Guo; Wang, Yuan; Zhang, Kai-Zhi; Yang, Guo-Jun; Shi, Jin-Shui; Deng, Jian-Jun; Li, Jin

    2014-01-01

    One kind of instantaneous electron beam emittance measurement system based on the optical transition radiation principle and double imaging optical method has been set up. It is mainly adopted in the test for the intense electron-beam produced by a linear induction accelerator. The system features two characteristics. The first one concerns the system synchronization signal triggered by the following edge of the main output waveform from a Blumlein switch. The synchronous precision of about 1 ns between the electron beam and the image capture time can be reached in this way so that the electron beam emittance at the desired time point can be obtained. The other advantage of the system is the ability to obtain the beam spot and beam divergence in one measurement so that the calculated result is the true beam emittance at that time, which can explain the electron beam condition. It provides to be a powerful beam diagnostic method for a 2.5 kA, 18.5 MeV, 90 ns (FWHM) electron beam pulse produced by Dragon I. The ability of the instantaneous measurement is about 3 ns and it can measure the beam emittance at any time point during one beam pulse. A series of beam emittances have been obtained for Dragon I. The typical beam spot is 9.0 mm (FWHM) in diameter and the corresponding beam divergence is about 10.5 mrad.

  14. GPU-Accelerated Hybrid Algorithm for 3D Localization of Fluorescent Emitters in Dense Clusters

    NASA Astrophysics Data System (ADS)

    Jung, Yoon; Barsic, Anthony; Piestun, Rafael; Fakhri, Nikta

    In stochastic switching-based super-resolution imaging, a random subset of fluorescent emitters are imaged and localized for each frame to construct a single high resolution image. However, the condition of non-overlapping point spread functions (PSFs) imposes constraints on experimental parameters. Recent development in post processing methods such as dictionary-based sparse support recovery using compressive sensing has shown up to an order of magnitude higher recall rate than single emitter fitting methods. However, the computational complexity of this approach scales poorly with the grid size and requires long runtime. Here, we introduce a fast and accurate compressive sensing algorithm for localizing fluorescent emitters in high density in 3D, namely sparse support recovery using Orthogonal Matching Pursuit (OMP) and L1-Homotopy algorithm for reconstructing STORM images (SOLAR STORM). SOLAR STORM combines OMP with L1-Homotopy to reduce computational complexity, which is further accelerated by parallel implementation using GPUs. This method can be used in a variety of experimental conditions for both in vitro and live cell fluorescence imaging.

  15. Plasma characteristics in the discharge region of a 20 A emission current hollow cathode

    NASA Astrophysics Data System (ADS)

    Mingming, SUN; Tianping, ZHANG; Xiaodong, WEN; Weilong, GUO; Jiayao, SONG

    2018-02-01

    Numerical calculation and fluid simulation methods were used to obtain the plasma characteristics in the discharge region of the LIPS-300 ion thruster’s 20 A emission current hollow cathode and to verify the structural design of the emitter. The results of the two methods indicated that the highest plasma density and electron temperature, which improved significantly in the orifice region, were located in the discharge region of the hollow cathode. The magnitude of plasma density was about 1021 m-3 in the emitter and orifice regions, as obtained by numerical calculations, but decreased exponentially in the plume region with the distance from the orifice exit. Meanwhile, compared to the emitter region, the electron temperature and current improved by about 36% in the orifice region. The hollow cathode performance test results were in good agreement with the numerical calculation results, which proved that that the structural design of the emitter and the orifice met the requirements of a 20 A emission current. The numerical calculation method can be used to estimate plasma characteristics in the preliminary design stage of hollow cathodes.

  16. Comparison of simulations with PHITS and HIBRAC with experimental data in the context of particle therapy monitoring

    PubMed Central

    Rohling, Heide; Sihver, Lembit; Priegnitz, Marlen; Enghardt, Wolfgang; Fiedler, Fine

    2014-01-01

    Therapeutic irradiation with protons and ions is advantageous over radiotherapy with photons due to its favorable dose deposition. Additionally, ion beams provide a higher relative biological effectiveness than photons. For this reason, an improved treatment of deep-seated tumors is achieved and normal tissue is spared. However, small deviations from the treatment plan can have a large impact on the dose distribution. Therefore, a monitoring is required to assure the quality of the treatment. Particle therapy positron emission tomography (PT-PET) is the only clinically proven method which provides a non-invasive monitoring of dose delivery. It makes use of the β+-activity produced by nuclear fragmentation during irradiation. In order to evaluate these PT-PET measurements, simulations of the β+-activity are necessary. Therefore, it is essential to know the yields of the β+-emitting nuclides at every position of the beam path as exact as possible. We evaluated the three-dimensional Monte-Carlo simulation tool PHITS (version 2.30) [ 1] and the 1D deterministic simulation tool HIBRAC [ 2] with respect to the production of β+-emitting nuclides. The yields of the most important β+-emitting nuclides for carbon, lithium, helium and proton beams have been calculated. The results were then compared with experimental data obtained at GSI Helmholtzzentrum für Schwerionenforschung Darmstadt, Germany. GEANT4 simulations provide an additional benchmark [ 3]. For PHITS, the impact of different nuclear reaction models, total cross-section models and evaporation models on the β+-emitter production has been studied. In general, PHITS underestimates the yields of positron-emitters and cannot compete with GEANT4 so far. The β+-emitters calculated with an extended HIBRAC code were in good agreement with the experimental data for carbon and proton beams and comparable to the GEANT4 results, see [ 4] and Fig. 1. Considering the simulation results and its speed compared with three-dimensional Monte-Carlo tools, HIBRAC is a good candidate for the implementation in clinical routine PT-PET. Fig 1.Depth-dependent yields of the production of 11C and 15O during proton irradiation of a PMMA target with 140 MeV [ 4].

  17. PET imaging for treatment verification of ion therapy: Implementation and experience at GSI Darmstadt and MGH Boston

    NASA Astrophysics Data System (ADS)

    Parodi, Katia; Bortfeld, Thomas; Enghardt, Wolfgang; Fiedler, Fine; Knopf, Antje; Paganetti, Harald; Pawelke, Jörg; Shakirin, Georgy; Shih, Helen

    2008-06-01

    Ion beams offer the possibility of improved conformation of the dose delivered to the tumor with better sparing of surrounding tissue and critical structures in comparison to conventional photon and electron external radiation treatment modalities. Full clinical exploitation of this advantage can benefit from in vivo confirmation of the actual beam delivery and, in particular, of the ion range in the patient. During irradiation, positron emitters like 15O (half-life T1/2≈2 min) and 11C ( T1/2≈20 min) are formed in nuclear interactions between the ions and the tissue. Detection of this transient radioactivity via positron emission tomography (PET) and comparison with the expectation based on the prescribed beam application may serve as an in vivo, non-invasive range validation method of the whole treatment planning and delivery chain. For technical implementation, PET imaging during irradiation (in-beam) requires the development of customized, limited angle detectors with data acquisition synchronized with the beam delivery. Alternatively, commercial PET or PET/CT scanners in close proximity to the treatment site enable detection of the residual activation from long-lived emitters shortly after treatment (offline). This paper reviews two clinical examples using a dedicated in-beam PET scanner for verification of carbon ion therapy at GSI Darmstadt, Germany, as well as a commercial offline PET/CT tomograph for post-radiation imaging of proton treatments at Massachusetts General Hospital, Boston, USA. Challenges as well as pros and cons of the two imaging approaches in dependence of the different ion type and beam delivery system are discussed.

  18. Techniques for correcting velocity and density fluctuations of ion beams in ion inducti on accelerators

    NASA Astrophysics Data System (ADS)

    Woo, K. M.; Yu, S. S.; Barnard, J. J.

    2013-06-01

    It is well known that the imperfection of pulse power sources that drive the linear induction accelerators can lead to time-varying fluctuation in the accelerating voltages, which in turn leads to longitudinal emittance growth. We show that this source of emittance growth is correctable, even in space-charge dominated beams with significant transients induced by space-charge waves. Two correction methods are proposed, and their efficacy in reducing longitudinal emittance is demonstrated with three-dimensional particle-in-cell simulations.

  19. Polarization measurements made on LFRA and OASIS emitter arrays

    NASA Astrophysics Data System (ADS)

    Geske, Jon; Sparkman, Kevin; Oleson, Jim; Laveigne, Joe; Sieglinger, Breck; Marlow, Steve; Lowry, Heard; Burns, James

    2008-04-01

    Polarization is increasingly being considered as a method of discrimination in passive sensing applications. In this paper the degree of polarization of the thermal emission from the emitter arrays of two new Santa Barbara Infrared (SBIR) micro-bolometer resistor array scene projectors was characterized at ambient temperature and at 77 K. The emitter arrays characterized were from the Large Format Resistive Array (LFRA) and the Optimized Arrays for Space-Background Infrared Simulation (OASIS) scene projectors. This paper reports the results of this testing.

  20. Apparatus and method for improving radiation coherence and reducing beam emittance

    DOEpatents

    Csonka, P.L.

    1992-05-12

    A method and apparatus for increasing the coherence and reducing the emittance of a beam-shaped pulse operates by splitting the pulse into multiple sub-beams, delaying the propagation of the various sub-beams by varying amounts, and then recombining the sub-beams by means of a rotating optical element to form a pulse of longer duration with improved transverse coherence. 16 figs.

  1. Apparatus and method for improving radiation coherence and reducing beam emittance

    DOEpatents

    Csonka, Paul L.

    1992-01-01

    A method and apparatus for increasing the coherence and reducing the emittance of a beam-shaped pulse operates by splitting the pulse into multiple sub-beams, delaying the propagation of the various sub-beams by varying amounts, and then recombining the sub-beams by means of a rotating optical element to form a pulse of longer duration with improved transverse coherence.

  2. Electron cyclotron resonance ion source experience at the Heidelberg Ion Beam Therapy Centera)

    NASA Astrophysics Data System (ADS)

    Winkelmann, T.; Cee, R.; Haberer, T.; Naas, B.; Peters, A.; Scheloske, S.; Spädtke, P.; Tinschert, K.

    2008-02-01

    Radiotherapy with heavy ions is an upcoming cancer treatment method with to date unparalleled precision. It associates higher control rates particularly for radiation resistant tumor species with reduced adverse effects compared to conventional photon therapy. The accelerator beam lines and structures of the Heidelberg Ion Beam Therapy Center (HIT) have been designed under the leadership of GSI, Darmstadt with contributions of the IAP Frankfurt. Currently, the accelerator is under commissioning, while the injector linac has been completed. When the patient treatment begins in 2008, HIT will be the first medical heavy ion accelerator in Europe. This presentation will provide an overview about the project, with special attention given to the 14.5GHz electron cyclotron resonance (ECR) ion sources in operation with carbon, hydrogen, helium, and oxygen, and the experience of one year of continuous operation. It also displays examples for beam emittances, measured in the low energy beam transport. In addition to the outlook of further developments at the ECR ion sources for a continuously stable operation, this paper focuses on some of the technical processings of the past year.

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  4. Resonant tunneling device with two-dimensional quantum well emitter and base layers

    DOEpatents

    Simmons, J.A.; Sherwin, M.E.; Drummond, T.J.; Weckwerth, M.V.

    1998-10-20

    A double electron layer tunneling device is presented. Electrons tunnel from a two dimensional emitter layer to a two dimensional tunneling layer and continue traveling to a collector at a lower voltage. The emitter layer is interrupted by an isolation etch, a depletion gate, or an ion implant to prevent electrons from traveling from the source along the emitter to the drain. The collector is similarly interrupted by a backgate, an isolation etch, or an ion implant. When the device is used as a transistor, a control gate is added to control the allowed energy states of the emitter layer. The tunnel gate may be recessed to change the operating range of the device and allow for integrated complementary devices. Methods of forming the device are also set forth, utilizing epoxy-bond and stop etch (EBASE), pre-growth implantation of the backgate or post-growth implantation. 43 figs.

  5. Resonant tunneling device with two-dimensional quantum well emitter and base layers

    DOEpatents

    Simmons, Jerry A.; Sherwin, Marc E.; Drummond, Timothy J.; Weckwerth, Mark V.

    1998-01-01

    A double electron layer tunneling device is presented. Electrons tunnel from a two dimensional emitter layer to a two dimensional tunneling layer and continue traveling to a collector at a lower voltage. The emitter layer is interrupted by an isolation etch, a depletion gate, or an ion implant to prevent electrons from traveling from the source along the emitter to the drain. The collector is similarly interrupted by a backgate, an isolation etch, or an ion implant. When the device is used as a transistor, a control gate is added to control the allowed energy states of the emitter layer. The tunnel gate may be recessed to change the operating range of the device and allow for integrated complementary devices. Methods of forming the device are also set forth, utilizing epoxy-bond and stop etch (EBASE), pre-growth implantation of the backgate or post-growth implantation.

  6. Characterization of the International Linear Collider damping ring optics

    NASA Astrophysics Data System (ADS)

    Shanks, J.; Rubin, D. L.; Sagan, D.

    2014-10-01

    A method is presented for characterizing the emittance dilution and dynamic aperture for an arbitrary closed lattice that includes guide field magnet errors, multipole errors and misalignments. This method, developed and tested at the Cornell Electron Storage Ring Test Accelerator (CesrTA), has been applied to the damping ring lattice for the International Linear Collider (ILC). The effectiveness of beam based emittance tuning is limited by beam position monitor (BPM) measurement errors, number of corrector magnets and their placement, and correction algorithm. The specifications for damping ring magnet alignment, multipole errors, number of BPMs, and precision in BPM measurements are shown to be consistent with the required emittances and dynamic aperture. The methodology is then used to determine the minimum number of position monitors that is required to achieve the emittance targets, and how that minimum depends on the location of the BPMs. Similarly, the maximum tolerable multipole errors are evaluated. Finally, the robustness of each BPM configuration with respect to random failures is explored.

  7. Integrated field emission array for ion desorption

    DOEpatents

    Resnick, Paul J; Hertz, Kristin L.; Holland, Christopher; Chichester, David

    2016-08-23

    An integrated field emission array for ion desorption includes an electrically conductive substrate; a dielectric layer lying over the electrically conductive substrate comprising a plurality of laterally separated cavities extending through the dielectric layer; a like plurality of conically-shaped emitter tips on posts, each emitter tip/post disposed concentrically within a laterally separated cavity and electrically contacting the substrate; and a gate electrode structure lying over the dielectric layer, including a like plurality of circular gate apertures, each gate aperture disposed concentrically above an emitter tip/post to provide a like plurality of annular gate electrodes and wherein the lower edge of each annular gate electrode proximate the like emitter tip/post is rounded. Also disclosed herein are methods for fabricating an integrated field emission array.

  8. Integrated field emission array for ion desorption

    DOEpatents

    Resnick, Paul J; Hertz, Kristin L; Holland, Christopher; Chichester, David; Schwoebel, Paul

    2013-09-17

    An integrated field emission array for ion desorption includes an electrically conductive substrate; a dielectric layer lying over the electrically conductive substrate comprising a plurality of laterally separated cavities extending through the dielectric layer; a like plurality of conically-shaped emitter tips on posts, each emitter tip/post disposed concentrically within a laterally separated cavity and electrically contacting the substrate; and a gate electrode structure lying over the dielectric layer, including a like plurality of circular gate apertures, each gate aperture disposed concentrically above an emitter tip/post to provide a like plurality of annular gate electrodes and wherein the lower edge of each annular gate electrode proximate the like emitter tip/post is rounded. Also disclosed herein are methods for fabricating an integrated field emission array.

  9. Studies of silicon pn junction solar cells

    NASA Technical Reports Server (NTRS)

    Lindholm, F. A.; Neugroschel, A.

    1977-01-01

    Modifications of the basic Shockley equations that result from the random and nonrandom spatial variations of the chemical composition of a semiconductor were developed. These modifications underlie the existence of the extensive emitter recombination current that limits the voltage over the open circuit of solar cells. The measurement of parameters, series resistance and the base diffusion length is discussed. Two methods are presented for establishing the energy bandgap narrowing in the heavily-doped emitter region. Corrections that can be important in the application of one of these methods to small test cells are examined. Oxide-charge-induced high-low-junction emitter (OCI-HLE) test cells which exhibit considerably higher voltage over the open circuit than was previously seen in n-on-p solar cells are described.

  10. Radioisotope generators for short-lived positron emitters applicable to positron emission tomography

    NASA Astrophysics Data System (ADS)

    Yano, Y.

    1989-04-01

    Radioisotope generators provide short-lived positron emitters for positron emission tomography (PET) without the need for an on-site cyclotron. These generators consist of a long-lived parent radionuclide, generally produced on an accelerator, from which the short-lived daughter radionuclide is separated and used as needed. Generators developed and applied to PET studies include 288 d 68Ge for 68 min 68Ga, 25 d 82Sr for 76 s 82Rb and 20.1 h 122Xe for 3.6 min 122I. These radiotracers have been used for the assessment of myocardial and brain blood flow in patient studies. Additionally, 82Rb has been used to determine the breakdown in the blood brain barrier in brain tumor patients who have undergone radiation therapy. When used in conjunction with 18F-fluorodeoxylucose produced on a regional cyclotron for the measurement of glucose utilization in brain tumors, differential diagnosis can be made between tumor regrowth and radiation therapy necrosis. Other possible applications include the detection of vascular lesions with 68Ga labeled platelets or porphyrins.

  11. A novel method for rapid in vitro radiobioassay

    NASA Astrophysics Data System (ADS)

    Crawford, Evan Bogert

    Rapid and accurate analysis of internal human exposure to radionuclides is essential to the effective triage and treatment of citizens who have possibly been exposed to radioactive materials in the environment. The two most likely scenarios in which a large number of citizens would be exposed are the detonation of a radiation dispersal device (RDD, "dirty bomb") or the accidental release of an isotope from an industrial source such as a radioisotopic thermal generator (RTG). In the event of the release and dispersion of radioactive materials into the environment in a large city, the entire population of the city -- including all commuting workers and tourists -- would have to be rapidly tested, both to satisfy the psychological needs of the citizens who were exposed to the mental trauma of a possible radiation dose, and to satisfy the immediate medical needs of those who received the highest doses and greatest levels of internal contamination -- those who would best benefit from rapid, intensive medical care. In this research a prototype rapid screening method to screen urine samples for the presence of up to five isotopes, both individually and in a mixture, has been developed. The isotopes used to develop this method are Co-60, Sr-90, Cs-137, Pu-238, and Am-241. This method avoids time-intensive chemical separations via the preparation and counting of a single sample on multiple detectors, and analyzing the spectra for isotope-specific markers. A rapid liquid-liquid separation using an organic extractive scintillator can be used to help quantify the activity of the alpha-emitting isotopes. The method provides quantifiable results in less than five minutes for the activity of beta/gamma-emitting isotopes when present in the sample at the intervention level as defined by the Centers for Disease Control and Prevention (CDC), and quantifiable results for the activity levels of alpha-emitting isotopes present at their respective intervention levels in approximately 30 minutes of sample preparation and counting time. Radiation detector spectra -- e.g. those from high-purity germanium (HPGe) gamma detectors and liquid scintillation detectors -- which contain decay signals from multiple isotopes often have overlapping signals: the counts from one isotope's decay can appear in energy channels associated with another isotope's decay, complicating the calculation of each isotope's activity. The uncertainties associated with analyzing these spectra have been traced in order to determine the effects of one isotope's count rate on the sensitivity and uncertainty associated with each other isotope. The method that was developed takes advantage of activated carbon filtration to eliminate quenching effects and to make the liquid scintillation spectra from different urine samples comparable. The method uses pulse-shape analysis to reduce the interference from beta emitters in the liquid scintillation spectrum and improve the minimum detectable activity (MDA) and minimum quantifiable activity (MQA) for alpha emitters. The method uses an HPGe detector to quantify the activity of gamma emitters, and subtract their isotopes' contributions to the liquid scintillation spectra via a calibration factor, such that the pure beta and pure alpha emitters can be identified and quantified from the resulting liquid scintillation spectra. Finally, the method optionally uses extractive scintillators to rapidly separate the alpha emitters from the beta emitters when the activity from the beta emitters is too great to detect or quantify the activity from the alpha emitters without such a separation. The method is able to detect and quantify all five isotopes, with uncertainties and biases usually in the 10-40% range, depending upon the isotopic mixtures and the activity ratios between each of the isotopes.

  12. Treatment of solid tumors by interstitial release of recoiling short-lived alpha emitters

    NASA Astrophysics Data System (ADS)

    Arazi, L.; Cooks, T.; Schmidt, M.; Keisari, Y.; Kelson, I.

    2007-08-01

    A new method utilizing alpha particles to treat solid tumors is presented. Tumors are treated with interstitial radioactive sources which continually release short-lived alpha emitting atoms from their surface. The atoms disperse inside the tumor, delivering a high dose through their alpha decays. We implement this scheme using thin wire sources impregnated with 224Ra, which release by recoil 220Rn, 216Po and 212Pb atoms. This work aims to demonstrate the feasibility of our method by measuring the activity patterns of the released radionuclides in experimental tumors. Sources carrying 224Ra activities in the range 10-130 kBq were used in experiments on murine squamous cell carcinoma tumors. These included gamma spectroscopy of the dissected tumors and major organs, Fuji-plate autoradiography of histological tumor sections and tissue damage detection by Hematoxylin-Eosin staining. The measurements focused on 212Pb and 212Bi. The 220Rn/216Po distribution was treated theoretically using a simple diffusion model. A simplified scheme was used to convert measured 212Pb activities to absorbed dose estimates. Both physical and histological measurements confirmed the formation of a 5-7 mm diameter necrotic region receiving a therapeutic alpha-particle dose around the source. The necrotic regions shape closely corresponded to the measured activity patterns. 212Pb was found to leave the tumor through the blood at a rate which decreased with tumor mass. Our results suggest that the proposed method, termed DART (diffusing alpha-emitters radiation therapy), may potentially be useful for the treatment of human patients.

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

    DOEpatents

    Hannon, Fay

    2016-08-02

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

  14. Chemical detection system and related methods

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Caffrey, Augustine J.; Chichester, David L.; Egger, Ann E.

    2017-06-27

    A chemical detection system includes a frame, an emitter coupled to the frame, and a detector coupled to the frame proximate the emitter. The system also includes a shielding system coupled to the frame and positioned at least partially between the emitter and the detector, wherein the frame positions a sensing surface of the detector in a direction substantially parallel to a plane extending along a front portion of the frame. A method of analyzing composition of a suspect object includes directing neutrons at the object, detecting gamma rays emitted from the object, and communicating spectrometer information regarding the gammamore » rays. The method also includes presenting a GUI to a user with a dynamic status of an ongoing neutron spectroscopy process. The dynamic status includes a present confidence for a plurality of compounds being present in the suspect object responsive to changes in the spectrometer information during the ongoing process.« less

  15. Selective solar absorber emittance measurement at elevated temperature

    NASA Astrophysics Data System (ADS)

    Giraud, Philémon; Braillon, Julien; Raccurt, Olivier

    2017-06-01

    Durability of solar components for CSP (Concentrated Solar Power Plant) technologies is a key point to lower cost and ensure their large deployment. These technologies concentrated the solar radiation by means of mirrors on a receiver tube where it is collected as thermal energy. The absorbers are submitted to strong environmental constraints and the degradation of their optical properties (emittance and solar absorbance) have a direct impact on performance. The characterization of a material in such condition is complicated and requires advanced apparatuses, and different measurement methods exist for the determination of the two quantities of relevance regarding an absorber, which are its emittance and its solar absorbance. The objective is to develop new optical equipment for measure the emittance of this solar absorber at elevated temperature. In this paper, we present an optical bench developed for emittance measurement on absorbers is conditions of use. Results will be shown, with a discussion of some factors of influence over this measurement and how to control them.

  16. A method of treating the non-grey error in total emittance measurements

    NASA Technical Reports Server (NTRS)

    Heaney, J. B.; Henninger, J. H.

    1971-01-01

    In techniques for the rapid determination of total emittance, the sample is generally exposed to surroundings that are at a different temperature than the sample's surface. When the infrared spectral reflectance of the surface is spectrally selective, these techniques introduce an error into the total emittance values. Surfaces of aluminum overcoated with oxides of various thicknesses fall into this class. Because they are often used as temperature control coatings on satellites, their emittances must be accurately known. The magnitude of the error was calculated for Alzak and silicon oxide-coated aluminum and was shown to be dependent on the thickness of the oxide coating. The results demonstrate that, because the magnitude of the error is thickness-dependent, it is generally impossible or impractical to eliminate it by calibrating the measuring device.

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

    NASA Astrophysics Data System (ADS)

    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.

  18. Design, fabrication, and experimental characterization of plasmonic photoconductive terahertz emitters.

    PubMed

    Berry, Christopher; Hashemi, Mohammad Reza; Unlu, Mehmet; Jarrahi, Mona

    2013-07-08

    In this video article we present a detailed demonstration of a highly efficient method for generating terahertz waves. Our technique is based on photoconduction, which has been one of the most commonly used techniques for terahertz generation (1-8). Terahertz generation in a photoconductive emitter is achieved by pumping an ultrafast photoconductor with a pulsed or heterodyned laser illumination. The induced photocurrent, which follows the envelope of the pump laser, is routed to a terahertz radiating antenna connected to the photoconductor contact electrodes to generate terahertz radiation. Although the quantum efficiency of a photoconductive emitter can theoretically reach 100%, the relatively long transport path lengths of photo-generated carriers to the contact electrodes of conventional photoconductors have severely limited their quantum efficiency. Additionally, the carrier screening effect and thermal breakdown strictly limit the maximum output power of conventional photoconductive terahertz sources. To address the quantum efficiency limitations of conventional photoconductive terahertz emitters, we have developed a new photoconductive emitter concept which incorporates a plasmonic contact electrode configuration to offer high quantum-efficiency and ultrafast operation simultaneously. By using nano-scale plasmonic contact electrodes, we significantly reduce the average photo-generated carrier transport path to photoconductor contact electrodes compared to conventional photoconductors (9). Our method also allows increasing photoconductor active area without a considerable increase in the capacitive loading to the antenna, boosting the maximum terahertz radiation power by preventing the carrier screening effect and thermal breakdown at high optical pump powers. By incorporating plasmonic contact electrodes, we demonstrate enhancing the optical-to-terahertz power conversion efficiency of a conventional photoconductive terahertz emitter by a factor of 50 (10).

  19. Two-dimensional trilayer grating with a metal/insulator/metal structure as a thermophotovoltaic emitter.

    PubMed

    Song, Jinlin; Si, Mengting; Cheng, Qiang; Luo, Zixue

    2016-02-20

    A thermophotovoltaic system that converts thermal energy into electricity has considerable potential for applications in energy utilization fields. However, intensive emission in a wide spectral and angular range remains a challenge in improving system efficiency. This study proposes the use of a 2D trilayer grating with a tungsten/silica/tungsten (W/SiO2/W) structure on a tungsten substrate as a thermophotovoltaic emitter. The finite-difference time-domain method is employed to simulate the radiative properties of the proposed structure. A broadband high emittance with an average spectral emittance of 0.953 between 600 and 1800 nm can be obtained for both transverse magnetic and transverse electric polarized waves. On the basis of the inductance-capacitance circuit model and dispersion relation analyses, this phenomenon is mainly considered as the combined contribution of surface plasmon polaritons and magnetic polaritons. A parametric study is also conducted on the emittance spectrum of the proposed structure, considering geometric parameters, polar angles, and azimuthal angles for both TM and TE waves. The study demonstrates that the emitter has good wavelength selectivity and polarization insensitivity in a wide geometric and angular range.

  20. The 3-D numerical simulation research of vacuum injector for linear induction accelerator

    NASA Astrophysics Data System (ADS)

    Liu, Dagang; Xie, Mengjun; Tang, Xinbing; Liao, Shuqing

    2017-01-01

    Simulation method for voltage in-feed and electron injection of vacuum injector is given, and verification of the simulated voltage and current is carried out. The numerical simulation for the magnetic field of solenoid is implemented, and a comparative analysis is conducted between the simulation results and experimental results. A semi-implicit difference algorithm is adopted to suppress the numerical noise, and a parallel acceleration algorithm is used for increasing the computation speed. The RMS emittance calculation method of the beam envelope equations is analyzed. In addition, the simulated results of RMS emittance are compared with the experimental data. Finally, influences of the ferromagnetic rings on the radial and axial magnetic fields of solenoid as well as the emittance of beam are studied.

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

    NASA Astrophysics Data System (ADS)

    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.

  2. Omnidirectional structured light in a flexible configuration.

    PubMed

    Paniagua, Carmen; Puig, Luis; Guerrero, José J

    2013-10-14

    Structured light is a perception method that allows us to obtain 3D information from images of the scene by projecting synthetic features with a light emitter. Traditionally, this method considers a rigid configuration, where the position and orientation of the light emitter with respect to the camera are known and calibrated beforehand. In this paper we propose a new omnidirectional structured light system in flexible configuration, which overcomes the rigidness of the traditional structured light systems. We propose the use of an omnidirectional camera combined with a conic pattern light emitter. Since the light emitter is visible in the omnidirectional image, the computation of its location is possible. With this information and the projected conic in the omnidirectional image, we are able to compute the conic reconstruction, i.e., the 3D information of the conic in the space. This reconstruction considers the recovery of the depth and orientation of the scene surface where the conic pattern is projected. One application of our proposed structured light system in flexible configuration consists of a wearable omnicamera with a low-cost laser in hand for visual impaired personal assistance.

  3. On the Ionization and Ion Transmission Efficiencies of Different ESI-MS Interfaces

    PubMed Central

    Cox, Jonathan T.; Marginean, Ioan; Smith, Richard D.; Tang, Keqi

    2014-01-01

    The achievable sensitivity of electrospray ionization mass spectrometry (ESI-MS) is largely determined by the ionization efficiency in the ESI source and ion transmission efficiency through the ESI-MS interface. These performance characteristics are difficult to evaluate and compare across multiple platforms as it is difficult to correlate electrical current measurements to actual analyte ions reaching the detector of a mass spectrometer. We present an effective method to evaluate the overall ion utilization efficiency of an ESI-MS interface by measuring the total gas phase ion current transmitted through the interface and correlating it to the observed ion abundance measured in the corresponding mass spectrum. Using this method we systematically studied the ion transmission and ionization efficiencies of different ESI-MS interface configurations, including a single emitter/single inlet capillary, single emitter/multi-inlet capillary, and a subambient pressure ionization with nanoelectrospray (SPIN) MS interface with a single emitter and an emitter array, respectively. Our experimental results indicate that the overall ion utilization efficiency of SPIN-MS interface configurations exceeds that of the inlet capillary-based ESI-MS interface configurations. PMID:25267087

  4. On the ionization and ion transmission efficiencies of different ESI-MS interfaces.

    PubMed

    Cox, Jonathan T; Marginean, Ioan; Smith, Richard D; Tang, Keqi

    2015-01-01

    The achievable sensitivity of electrospray ionization mass spectrometry (ESI-MS) is largely determined by the ionization efficiency in the ESI source and ion transmission efficiency through the ESI-MS interface. These performance characteristics are difficult to evaluate and compare across multiple platforms as it is difficult to correlate electrical current measurements to actual analyte ions reaching the detector of a mass spectrometer. We present an effective method to evaluate the overall ion utilization efficiency of an ESI-MS interface by measuring the total gas-phase ion current transmitted through the interface and correlating it to the observed ion abundance measured in the corresponding mass spectrum. Using this method, we systematically studied the ion transmission and ionization efficiencies of different ESI-MS interface configurations, including a single emitter/single inlet capillary, single emitter/multi-inlet capillary, and a subambient pressure ionization with nanoelectrospray (SPIN) MS interface with a single emitter and an emitter array, respectively. Our experimental results indicate that the overall ion utilization efficiency of SPIN-MS interface configurations exceeds that of the inlet capillary-based ESI-MS interface configurations.

  5. The treatment of solid tumors by alpha emitters released from 224Ra-loaded sources—internal dosimetry analysis

    NASA Astrophysics Data System (ADS)

    Arazi, L.; Cooks, T.; Schmidt, M.; Keisari, Y.; Kelson, I.

    2010-02-01

    Diffusing alpha-emitters radiation therapy (DART) is a proposed new form of brachytherapy, allowing the treatment of solid tumors by alpha particles. DART utilizes implantable sources carrying small activities of radium-224, which continually release into the tumor radon-220, polonium-216 and lead-212 atoms, while radium-224 itself remains fixed to the source. The released atoms disperse inside the tumor by diffusive and convective processes, creating, through their alpha emissions, a high-dose region measuring several mm in diameter about each source. The efficacy of DART has been demonstrated in preclinical studies on mice-borne squamous cell carcinoma and lung tumors and the method is now being developed toward clinical trials. This work studies DART safety with respect to the dose delivered to distant organs as a result of lead-212 leakage from the tumor through the blood, relying on a biokinetic calculation coupled to internal dose assessments. It is found that the dose-limiting organs are the kidneys and red bone marrow. Assuming a typical source spacing of ~5 mm and a typical radium-224 activity density of 0.4-0.8 MBq g-1 of tumor tissue, it is predicted that tumors weighing up to several hundred grams may be treated without reaching the tolerance dose in any organ.

  6. THE APPLICATION OF RADIOISOTOPES IN SHIPBUILDING FOR NONDESTRUCTIVE MATERIAL TESTING

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gerlach, H.

    1962-02-01

    S>Safety and reliability in shipbuilding require exact testing methods for all materials, such as plates, sheets, rods, cast pieces, welded joints, etc. Non-visible defects in parts exposed to great stress may cause great damages. Since both x-ray and gamma radiography can detect these defects, a choice has to be made between these radiation sources. ln general, for very thick pieces, gamma emitters such as Co/sup 60/ or Ta/sup 182/ are used; for medium thick pieces, gamma emitters, such as Ir/sup 192/ or Cs/sup 137/ are used; for very thin pieces weak gamma emitters, such as Eu/sup 155/ or x raysmore » are used. There is no competition between x rays and gamma rays in nondestructive testing because both methods supplement each other. The tcchnical and economical advantages and disadvantages of both methods are discussed. In shipbuilding, Ir/ sup 192/ has extremely good irradiation qualities for sheets from 6 to 50 mm thick and is superior to the x-ray method for checking welds of sheets of this thickness. However, for materials thicker than 50 mm x rays are useless, and defects in this material must be located with hard gamma emitters, such as Co/ sup 60/. Recently, mobile test stations with radioisotopes were established which are of great value for checking and quality control in shipbuilding at the shipyard. (OID)« less

  7. Electromagnetic compatibility of implantable neurostimulators to RFID emitters

    PubMed Central

    2011-01-01

    Background The objective of this study is to investigate electromagnetic compatibility (EMC) of implantable neurostimulators with the emissions from radio frequency identification (RFID) emitters. Methods Six active implantable neurostimulators with lead systems were tested for susceptibility to electromagnetic fields generated by 22 RFID emitters. These medical devices have been approved for marketing in the U.S. for a number of intended uses that include: epilepsy, depression, incontinence, Parkinsonian tremor and pain relief. Each RFID emitter had one of the following carrier frequencies: 125 kHz, 134 kHz, 13.56 MHz, 433 MHz, 915 MHz and 2.45 GHz Results The test results showed the output of one of the implantable neurostimulators was inhibited by 134 kHz RFID emitter at separation distances of 10 cm or less. The output of the same implantable neurostimulator was also inhibited by another 134 kHz RFID emitter at separation distances of 10 cm or less and also showed inconsistent pulsing rate at a separation distance of 15 cm. Both effects occurred during and lasted through out the duration of the exposure. Conclusions The clinical significance of the effects was assessed by a clinician at the U.S. Food and Drug Administration. The effects were determined to be clinically significant only if they occurred for extended period of time. There were no observed effects from the other 5 implantable neurostimulators or during exposures from other RFID emitters. PMID:21658266

  8. SU-C-204-01: A Fast Analytical Approach for Prompt Gamma and PET Predictions in a TPS for Proton Range Verification

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kroniger, K; Herzog, M; Landry, G

    2015-06-15

    Purpose: We describe and demonstrate a fast analytical tool for prompt-gamma emission prediction based on filter functions applied on the depth dose profile. We present the implementation in a treatment planning system (TPS) of the same algorithm for positron emitter distributions. Methods: The prediction of the desired observable is based on the convolution of filter functions with the depth dose profile. For both prompt-gammas and positron emitters, the results of Monte Carlo simulations (MC) are compared with those of the analytical tool. For prompt-gamma emission from inelastic proton-induced reactions, homogeneous and inhomogeneous phantoms alongside with patient data are used asmore » irradiation targets of mono-energetic proton pencil beams. The accuracy of the tool is assessed in terms of the shape of the analytically calculated depth profiles and their absolute yields, compared to MC. For the positron emitters, the method is implemented in a research RayStation TPS and compared to MC predictions. Digital phantoms and patient data are used and positron emitter spatial density distributions are analyzed. Results: Calculated prompt-gamma profiles agree with MC within 3 % in terms of absolute yield and reproduce the correct shape. Based on an arbitrary reference material and by means of 6 filter functions (one per chemical element), profiles in any other material composed of those elements can be predicted. The TPS implemented algorithm is accurate enough to enable, via the analytically calculated positron emitters profiles, detection of range differences between the TPS and MC with errors of the order of 1–2 mm. Conclusion: The proposed analytical method predicts prompt-gamma and positron emitter profiles which generally agree with the distributions obtained by a full MC. The implementation of the tool in a TPS shows that reliable profiles can be obtained directly from the dose calculated by the TPS, without the need of full MC simulation.« less

  9. Treatment with tandem [90Y]DOTA-TATE and [177Lu]DOTA-TATE of neuroendocrine tumours refractory to conventional therapy.

    PubMed

    Seregni, E; Maccauro, M; Chiesa, C; Mariani, L; Pascali, C; Mazzaferro, V; De Braud, F; Buzzoni, R; Milione, M; Lorenzoni, A; Bogni, A; Coliva, A; Lo Vullo, S; Bombardieri, E

    2014-02-01

    Peptide receptor radionuclide therapy (PRRT) with radiolabelled somatostatin analogues has been demonstrated to be an effective therapeutic option in patients with disseminated neuroendocrine tumours (NET). Treatment with tandem [(90)Y]DOTA-TATE and [(177)Lu]DOTA-TATE may improve the efficacy of PRRT without increasing the toxicity. In a phase II study we evaluated the feasibility of combined PPRT with a high-energy beta emitter ((90)Y) and a medium-energy beta/gamma emitter ([(177)Lu) in patients with metastatic NET refractory to conventional therapy. A group of 26 patients with metastatic NET were treated with four therapeutic cycles of alternating [[(177)Lu]DOTA-TATE (5.55 GBq) and [(90)Y]DOTA-TATE (2.6 GBq). A dosimetric evaluation was carried out after administration of [[(177)Lu]DOTA-TATE to calculate the absorbed doses in healthy organs. The acute and long-term toxicities of repeated treatment were analysed. PRRT efficacy was evaluated according to RECIST. Administration of tandem [(90)Y]DOTA-TATE and [[(177)Lu]DOTA-TATE induced objective responses in 42.3 % of patients with metastatic NET with a median progression-free survival longer than 24 months. Of patients with pretreatment carcinoid syndrome, 90 % showed a symptomatic response or a reduction in tumour-associated pain. The cumulative biologically effective doses (BED) were below the toxicity limit in the majority of patients, in the absence of renal function impairment. The results of our study indicates that combined [(90)Y]DOTA-TATE and [(177)Lu]DOTA-TATE therapy is a feasible and effective therapeutic option in NET refractory to conventional therapy. Furthermore, the absence of kidney damage and the evaluated cumulative BEDs suggest that increasing the number of tandem administrations is an interesting approach.

  10. Modulation characteristics of graphene-based thermal emitters

    NASA Astrophysics Data System (ADS)

    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.

  11. Development and application of an emitter for research of an on-board ultraviolet polarimeter

    NASA Astrophysics Data System (ADS)

    Nevodovskyi, P. V.; Geraimchuk, M. D.; Vidmachenko, A. P.; Ivakhiv, O. V.

    2018-05-01

    In carrying out of the work a layout of on-board small-sized ultraviolet polarimeter (UVP) was created. UVP is the device, which provides an implementation of passive remote studies of stratospheric aerosol from the board of the microsatellite of the Earth by the method of polarimetry. For carrying out of tests and the research of polarimetric equipment, a special stand was created at MAO of NAS of Ukraine. In its composition is an ultraviolet emitter. Emitter is one of the main components of a special stand for the study of on-board ultraviolet polarimeters.

  12. Near atomically smooth alkali antimonide photocathode thin films

    DOE PAGES

    Feng, Jun; Karkare, Siddharth; Nasiatka, James; ...

    2017-01-24

    Nano-roughness is one of the major factors degrading the emittance of electron beams that can be generated by high efficiency photocathodes, such as the thermally reacted alkali antimonide thin films. In this paper, we demonstrate a co-deposition based method for producing alkali antimonide cathodes that produce near atomic smoothness with high reproducibility. Here, we calculate the effect of the surface roughness on the emittance and show that such smooth cathode surfaces are essential for operation of alkali antimonide cathodes in high field, low emittance radio frequency electron guns and to obtain ultracold electrons for ultrafast electron diffraction applications.

  13. Near atomically smooth alkali antimonide photocathode thin films

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Feng, Jun; Karkare, Siddharth; Nasiatka, James

    Nano-roughness is one of the major factors degrading the emittance of electron beams that can be generated by high efficiency photocathodes, such as the thermally reacted alkali antimonide thin films. In this paper, we demonstrate a co-deposition based method for producing alkali antimonide cathodes that produce near atomic smoothness with high reproducibility. Here, we calculate the effect of the surface roughness on the emittance and show that such smooth cathode surfaces are essential for operation of alkali antimonide cathodes in high field, low emittance radio frequency electron guns and to obtain ultracold electrons for ultrafast electron diffraction applications.

  14. Some Effects of Exposure to Exhaust-gas Streams on Emittance and Thermoelectric Power of Bare-wire Platinum Rhodium - Platinum Thermocouples

    NASA Technical Reports Server (NTRS)

    Glawe, George E; Shepard, Charles E

    1954-01-01

    Thermocouples were exposed to exhaust gases from the combustion of propane, 72-octane gasoline, and JP-4 fuel. Exposure increased the emissivity of the thermocouple wire, which increased its radiation error. Two methods are presented for determining the emittance of the wires. The emissivity of a clean platinum rhodium-platinum thermocouple was approximately 0.2 in the temperature range investigated, while the emittance of an exposed thermocouple coated with exhaust residue was about 0.5. The exposure caused negligible change in the thermoelectric power of the thermocouples.

  15. In-situ grown MgO-ZnO ceramic coating with high thermal emittance on Mg alloy by plasma electrolytic oxidation

    NASA Astrophysics Data System (ADS)

    Li, Hang; Lu, Songtao; Qin, Wei; Wu, Xiaohong

    2017-07-01

    Intense solar radiation and internal heat generation determine the equilibrium temperature of an in-orbit spacecraft. Thermal control coatings with low solar absorptance and high thermal emittance effectively maintain the thermal equilibrium within safe operating limits for exposed, miniaturized and highly integrated components. A novel ceramic coating with high thermal emittance and good adhesion was directly prepared on the Mg substrate using an economical process of controlled plasma electrolytic oxidation (PEO) in the electrolyte containing ZnSO4. XRD and XPS results showed that this coating was mainly composed of the MgO phase as well as an unusual ZnO crystalline phase. The adhesive strength between the coating and substrate determined by a pull-off test revealed an excellent adhesion. Thermal and optical properties test revealed that the coating exhibited a high infrared emittance of 0.88 (2-16 μm) and low solar absorptance of 0.35 (200-2500 nm). The result indicated that the formation of ZnO during the PEO process played an important role in the improvement of the coating emittance. The process developed provides a simple surface method for improving the thermal emittance of Mg alloy, which presents a promising application prospect in the thermal management of the spacecraft.

  16. 20-mN Variable Specific Impulse (Isp) Colloid Thruster

    NASA Technical Reports Server (NTRS)

    Demmons, Nathaniel

    2015-01-01

    Busek Company, Inc., has designed and manufactured an electrospray emitter capable of generating 20 mN in a compact package (7x7x1.7 in). The thruster consists of nine porous-surface emitters operating in parallel from a common propellant supply. Each emitter is capable of supporting over 70,000 electrospray emission sites with the plume from each emitter being accelerated through a single aperture, eliminating the need for individual emission site alignment to an extraction grid. The total number of emission sites during operation is expected to approach 700,000. This Phase II project optimized and characterized the thruster fabricated during the Phase I effort. Additional porous emitters also were fabricated for full-scale testing. Propellant is supplied to the thruster via existing feed-system and microvalve technology previously developed by Busek, under the NASA Space Technology 7's Disturbance Reduction System (ST7-DRS) mission and via follow-on electric propulsion programs. This project investigated methods for extending thruster life beyond the previously demonstrated 450 hours. The life-extending capabilities will be demonstrated on a subscale version of the thruster.

  17. Design and Development of Emittance Measurement Device by Using the Pepper-pot Technique

    NASA Astrophysics Data System (ADS)

    Pakluea, S.; Rimjaem, S.

    2017-09-01

    Transverse emittance of a charged particle beam is one of the most important properties that reveals the quality of the beam. It is related to charge density, transvers size and angular displacement of the beam in transverse phase space. There are several techniques to measure the transverse emittance value. One of practical methods is the pepper-pot technique, which can measure both horizontal and vertical emittance value in a single measurement. This research concentrates on development of a pepper-pot device to measure the transverse emittance of electron beam produced from an accelerator injector system, which consists of a thermionic cathode RF electron gun and an alpha magnet, at the Plasma and Beam Physics Research Facility, Chiang Mai University. Simulation of beam dynamics was conducted with programs PARMELA, ELEGANT and self-developed codes using C and MATLAB. The geometry, dimensions and location of the pepper-pot as well as its corresponding screen station position were included in the simulation. The result from this study will be used to design and develop a practical pepper-pot experimental station.

  18. Variations in the concentration of plutonium, strontium-90 and total alpha-emitters in human teeth collected within the British Isles.

    PubMed

    O'Donnell, R G; Mitchell, P I; Priest, N D; Strange, L; Fox, A; Henshaw, D L; Long, S C

    1997-08-18

    Concentrations of plutonium-239, plutonium-240, strontium-90 and total alpha-emitters have been measured in children's teeth collected throughout Great Britain and Ireland. The concentrations of plutonium and strontium-90 were measured in batched samples, each containing approximately 50 teeth, using low-background radiochemical methods. The concentrations of total alpha-emitters were determined in single teeth using alpha-sensitive plastic track detectors. The results showed that the average concentrations of total alpha-emitters and strontium-90 were approximately one to three orders of magnitude greater than the equivalent concentrations of plutonium-239,240. Regression analyses indicated that the concentrations of plutonium, but not strontium-90 or total alpha-emitters, decreased with increasing distance from the Sellafield nuclear fuel reprocessing plant-suggesting that this plant is a source of plutonium contamination in the wider population of the British Isles. Nevertheless, the measured absolute concentrations of plutonium (mean = 5 +/- 4 mBq kg-1 ash wt.) were so low that they are considered to present an insignificant radiological hazard.

  19. Measuring true localization accuracy in super resolution microscopy with DNA-origami nanostructures

    NASA Astrophysics Data System (ADS)

    Reuss, Matthias; Fördős, Ferenc; Blom, Hans; Öktem, Ozan; Högberg, Björn; Brismar, Hjalmar

    2017-02-01

    A common method to assess the performance of (super resolution) microscopes is to use the localization precision of emitters as an estimate for the achieved resolution. Naturally, this is widely used in super resolution methods based on single molecule stochastic switching. This concept suffers from the fact that it is hard to calibrate measures against a real sample (a phantom), because true absolute positions of emitters are almost always unknown. For this reason, resolution estimates are potentially biased in an image since one is blind to true position accuracy, i.e. deviation in position measurement from true positions. We have solved this issue by imaging nanorods fabricated with DNA-origami. The nanorods used are designed to have emitters attached at each end in a well-defined and highly conserved distance. These structures are widely used to gauge localization precision. Here, we additionally determined the true achievable localization accuracy and compared this figure of merit to localization precision values for two common super resolution microscope methods STED and STORM.

  20. A method for optimum PSA setting in the absence of a pure α or β emitter and its application in the determination of (237)Np/(233)Pa.

    PubMed

    Feng, Xiao-gui; He, Qian-ge; Wang, Jian-chen; Chen, Jing

    2014-11-01

    In the application of liquid scintillation counting (LSC), the α/β discrimination is carried out with the function of pulse shape analysis (PSA), which requires the setting of the optimum PSA level. The optimum PSA are usually determined by the generation of cross-over plots, whereby a pair of vials, one containing a pure α emitter and the other a pure β emitter, is counted. However, in some cases such as the determination of (237)Np/(233)Pa, a pure α emitter or a pure β emitter is not available. Therefore, we have developed a new approach to set the optimum PSA by measuring the sample itself of mixed α/β emitters. The count rate of the sample in the α-multi-channel analyzer changes monotonically with the increase of the PSA, and there is always an inflection point which is related to the optimum PSA. By fitting the data near the inflection point with the function y=ax(3)+bx(2)+cx+d, we can obtain the optimum PSA as -b/(3a), which can be used to determine the radioactivity of (237)Np/(233)Pa. The results obtained with this new approach were in good agreement with those obtained by HPGe γ spectrometry that was calibrated with an LSC sample of (237)Np/(233)Pa under a radioactive secular equilibrium. The new approach is promising to be used in simultaneous determination of gross α and β emitters, especially in the absence of a pure α or β emitter. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Design study of an in situ PET scanner for use in proton beam therapy

    NASA Astrophysics Data System (ADS)

    Surti, S.; Zou, W.; Daube-Witherspoon, M. E.; McDonough, J.; Karp, J. S.

    2011-05-01

    Proton beam therapy can deliver a high radiation dose to a tumor without significant damage to surrounding healthy tissue or organs. One way of verifying the delivered dose distribution is to image the short-lived positron emitters produced by the proton beam as it travels through the patient. A potential solution to the limitations of PET imaging in proton beam therapy is the development of a high sensitivity, in situ PET scanner that starts PET imaging almost immediately after patient irradiation while the patient is still lying on the treatment bed. A partial ring PET design is needed for this application in order to avoid interference between the PET detectors and the proton beam, as well as restrictions on patient positioning on the couch. A partial ring also allows us to optimize the detector separation (and hence the sensitivity) for different patient sizes. Our goal in this investigation is to evaluate an in situ PET scanner design for use in proton therapy that provides tomographic imaging in a partial ring scanner design using time-of-flight (TOF) information and an iterative reconstruction algorithm. GEANT4 simulation of an incident proton beam was used to produce a positron emitter distribution, which was parameterized and then used as the source distribution inside a water-filled cylinder for EGS4 simulations of a PET system. Design optimization studies were performed as a function of crystal type and size, system timing resolution, scanner angular coverage and number of positron emitter decays. Data analysis was performed to measure the accuracy of the reconstructed positron emitter distribution as well as the range of the positron emitter distribution. We simulated scanners with varying crystal sizes (2-4 mm) and type (LYSO and LaBr3) and our results indicate that 4 mm wide LYSO or LaBr3 crystals (resulting in 4-5 mm spatial resolution) are adequate; for a full-ring, non-TOF scanner we predict a low bias (<0.6 mm) and a good precision (<1 mm) in the estimated range relative to the simulated positron distribution. We then varied the angular acceptance of the scanner ranging from 1/2 to 2/3 of 2π a partial ring TOF imaging with good timing resolution (<=600 ps) is necessary to produce accurate tomographic images. A two-third ring scanner with 300 ps timing resolution leads to a bias of 1.0 mm and a precision of 1.4 mm in the range estimate. With a timing resolution of 600 ps, the bias increases to 2.0 mm while the precision in the range estimate is similar. For a half-ring scanner design, more distortions are present in the image, which is characterized by the increased error in the profile difference estimate. We varied the number of positron decays imaged by the PET scanner by an order of magnitude and we observe some decrease in the precision of the range estimate for lower number of decays, but all partial ring scanner designs studied have a precision <=1.5 mm. The largest number tested, 150 M total positron decays, is considered realistic for a clinical fraction of delivered dose, while the range of positron decays investigated in this work covers a variable number of situations corresponding to delays in scan start time and the total scan time. Thus, we conclude that for partial ring systems, an angular acceptance of at least 1/2 (of 2π) together with timing resolution of 300 ps is needed to achieve accurate and precise range estimates. With 600 ps timing resolution an angular acceptance of 2/3 (of 2π) is required to achieve satisfactory range estimates. These results indicate that it would be feasible to develop a partial-ring dedicated PET scanner based on either LaBr3 or LYSO to accurately characterize the proton dose for therapy planning.

  2. MOLECULAR SIEVES ADSORB IODINE-131 FROM AIR

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wahlgren, M.A.; Meinke, W.W.

    1957-09-01

    Consideration has been given to the problem of separating and estimating U, Po, nnd other alpha emitters (in order to provide analytical methods for their routine determination in conformity with the draft agreement on the Harwell effluent). Uranium may be ether extracted from solutions of NH/sub 4/NO/sub 3/ as salting out agent at pH1 with an efficiency of 98 to 99%. The deposition of Po on Ag foil is a specific method for this element and under prescribed conditions similar extraction efficiencies may be obtained. An adequate separation from all "other alpha emitters" is obtained and methods for the estimationmore » of these are discussed. A comprehensive scheme involving a preliminary activity concentration step has been elaborated. U, Po, and the majority of the "other alpha emitters" are precipitated as their tannin complexes at pH8 using Ca(OH)/sub 2/, the calcium-tannin complex acting as a carrier. That part of the activity remaining in solution is determined as in the total activity method, previously described. From the solution of the precipitate, Po is first separated by electrodeposition, and then U by ether extraction in the presence of NH/sub 4/NO/sub 3/. The majority of the "other alpha emitters" still in the aqueous NH/sub 4/NO/sub 3/ solution are collected on a second calcium-tannin precipitate, while the small part remaining in solution after this operation is obtained by direct evaporation. (auth)« less

  3. On the effectiveness of ion range determination from in-beam PET data

    NASA Astrophysics Data System (ADS)

    Fiedler, Fine; Shakirin, Georgy; Skowron, Judith; Braess, Henning; Crespo, Paulo; Kunath, Daniela; Pawelke, Jörg; Pönisch, Falk; Enghardt, Wolfgang

    2010-04-01

    At present, in-beam positron emission tomography (PET) is the only method for in vivo and in situ range verification in ion therapy. At the GSI Helmholtzzentrum für Schwerionenforschung GmbH (GSI) Darmstadt, Germany, a unique in-beam PET installation has been operated from 1997 until the shut down of the carbon ion therapy facility in 2008. Therapeutic irradiation by means of 12C ion beams of more than 400 patients have been monitored. In this paper a first quantitative study on the accuracy of the in-beam PET method to detect range deviations between planned and applied treatment in clinically relevant situations using simulations based on clinical data is presented. Patient treatment plans were used for performing simulations of positron emitter distributions. For each patient a range difference of ± 6 mm in water was applied and compared to simulations without any changes. The comparisons were performed manually by six experienced evaluators for data of 81 patients. The number of patients required for the study was calculated using the outcome of a pilot study. The results indicate a sensitivity of (91 ± 3)% and a specificity of (96 ± 2)% for detecting an overrange, a reduced range is recognized with a sensitivity of (92 ± 3)% and a specificity of (96 ± 2)%. The positive and the negative predictive value of this method are 94% and 87%, respectively. The interobserver coefficient of variation is between 3 and 8%. The in-beam PET method demonstrated a high sensitivity and specificity for the detection of range deviations. As the range is a most indicative factor of deviations in the dose delivery, the promising results shown in this paper confirm the in-beam PET method as an appropriate tool for monitoring ion therapy.

  4. Vertically aligned carbon nanotube emitter on metal foil for medical X-ray imaging.

    PubMed

    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.

  5. Radio frequency detection assembly and method for detecting radio frequencies

    DOEpatents

    Cown, Steven H.; Derr, Kurt Warren

    2010-03-16

    A radio frequency detection assembly is described and which includes a radio frequency detector which detects a radio frequency emission produced by a radio frequency emitter from a given location which is remote relative to the radio frequency detector; a location assembly electrically coupled with the radio frequency detector and which is operable to estimate the location of the radio frequency emitter from the radio frequency emission which has been received; and a radio frequency transmitter electrically coupled with the radio frequency detector and the location assembly, and which transmits a radio frequency signal which reports the presence of the radio frequency emitter.

  6. Suppression of the emittance growth induced by coherent synchrotron radiation in triple-bend achromats

    NASA Astrophysics Data System (ADS)

    Huang, Xi-Yang; Jiao, Yi; Xu, Gang; Cui, Xiao-Hao

    2015-05-01

    The coherent synchrotron radiation (CSR) effect in a bending path plays an important role in transverse emittance dilution in high-brightness light sources and linear colliders, where the electron beams are of short bunch length and high peak current. Suppression of the emittance growth induced by CSR is critical to preserve the beam quality and help improve the machine performance. It has been shown that the CSR effect in a double-bend achromat (DBA) can be analyzed with the two-dimensional point-kick analysis method. In this paper, this method is applied to analyze the CSR effect in a triple-bend achromat (TBA) with symmetric layout, which is commonly used in the optics designs of energy recovery linacs (ERLs). A condition of cancelling the CSR linear effect in such a TBA is obtained, and is verified through numerical simulations. It is demonstrated that emittance preservation can be achieved with this condition, and to a large extent, has a high tolerance to the fluctuation of the initial transverse phase space distribution of the beam. Supported by National Natural Science Foundation of China (11475202, 11405187) and Youth Innovation Promotion Association of Chinese Academy of Sciences (2015009)

  7. Decoupling Intensity Radiated by the Emitter in Distance Estimation from Camera to IR Emitter

    PubMed Central

    Cano-García, Angel E.; Galilea, José Luis Lázaro; Fernández, Pedro; Infante, Arturo Luis; Pompa-Chacón, Yamilet; Vázquez, Carlos Andrés Luna

    2013-01-01

    Various models using radiometric approach have been proposed to solve the problem of estimating the distance between a camera and an infrared emitter diode (IRED). They depend directly on the radiant intensity of the emitter, set by the IRED bias current. As is known, this current presents a drift with temperature, which will be transferred to the distance estimation method. This paper proposes an alternative approach to remove temperature drift in the distance estimation method by eliminating the dependence on radiant intensity. The main aim was to use the relative accumulated energy together with other defined models, such as the zeroth-frequency component of the FFT of the IRED image and the standard deviation of pixel gray level intensities in the region of interest containing the IRED image. By using the abovementioned models, an expression free of IRED radiant intensity was obtained. Furthermore, the final model permitted simultaneous estimation of the distance between the IRED and the camera and the IRED orientation angle. The alternative presented in this paper gave a 3% maximum relative error over a range of distances up to 3 m. PMID:23727954

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

    PubMed

    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.

  9. Current-horn suppression for reduced coherent-synchrotron-radiation-induced emittance growth in strong bunch compression

    NASA Astrophysics Data System (ADS)

    Charles, T. K.; Paganin, D. M.; Latina, A.; Boland, M. J.; Dowd, R. T.

    2017-03-01

    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.

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

    DOEpatents

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

    2016-08-16

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

  11. Planar Field Emitters and High Efficiency Photocathodes Based on Ultrananocrystalline Diamond

    NASA Technical Reports Server (NTRS)

    Sumant, Anirudha V. (Inventor); Baryshev, Sergey V. (Inventor); Antipov, Sergey P. (Inventor)

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Dynamic imperfections and optimized feedback design in the Compact Linear Collider main linac

    NASA Astrophysics Data System (ADS)

    Eliasson, Peder

    2008-05-01

    The Compact Linear Collider (CLIC) main linac is sensitive to dynamic imperfections such as element jitter, injected beam jitter, and ground motion. These effects cause emittance growth that, in case of ground motion, has to be counteracted by a trajectory feedback system. The feedback system itself will, due to jitter effects and imperfect beam position monitors (BPMs), indirectly cause emittance growth. Fast and accurate simulations of both the direct and indirect effects are desirable, but due to the many elements of the CLIC main linac, simulations may become very time consuming. In this paper, an efficient way of simulating linear (or nearly linear) dynamic effects is described. The method is also shown to facilitate the analytic determination of emittance growth caused by the different dynamic imperfections while using a trajectory feedback system. Emittance growth expressions are derived for quadrupole, accelerating structure, and beam jitter, for ground motion, and for noise in the feedback BPMs. Finally, it is shown how the method can be used to design a feedback system that is optimized for the optics of the machine and the ground motion spectrum of the particular site. This feedback system gives an emittance growth rate that is approximately 10 times lower than that of traditional trajectory feedbacks. The robustness of the optimized feedback system is studied for a number of additional imperfections, e.g., dipole corrector imperfections and faulty knowledge about the machine optics, with promising results.

  14. Compact representations of partially coherent undulator radiation suitable for wave propagation

    DOE PAGES

    Lindberg, Ryan R.; Kim, Kwang -Je

    2015-09-28

    Undulator radiation is partially coherent in the transverse plane, with the degree of coherence depending on the ratio of the electron beam phase space area (emittance) to the characteristic radiation wavelength λ. Numerical codes used to predict x-ray beam line performance can typically only propagate coherent fields from the source to the image plane. We investigate methods for representing partially coherent undulator radiation using a suitably chosen set of coherent fields that can be used in standard wave propagation codes, and discuss such “coherent mode expansions” for arbitrary degrees of coherence. In the limit when the electron beam emittance alongmore » at least one direction is much larger than λ the coherent modes are orthogonal and therefore compact; when the emittance approaches λ in both planes we discuss an economical method of defining the relevant coherent fields that samples the electron beam phase space using low-discrepancy sequences.« less

  15. Numerical simulations of the charged-particle flow dynamics for sources with a curved emission surface

    NASA Astrophysics Data System (ADS)

    Altsybeyev, V. V.

    2016-12-01

    The implementation of numerical methods for studying the dynamics of particle flows produced by pulsed sources is discussed. A particle tracking method with so-called gun iteration for simulations of beam dynamics is used. For the space charge limited emission problem, we suggest a Gauss law emission model for precise current-density calculation in the case of a curvilinear emitter. The results of numerical simulations of particle-flow formation for cylindrical bipolar diode and for diode with elliptical emitter are presented.

  16. High quality GaAs single photon emitters on Si substrate

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bietti, S.; Sanguinetti, S.; Cavigli, L.

    2013-12-04

    We describe a method for the direct epitaxial growth of a single photon emitter, based on GaAs quantum dots fabricated by droplet epitaxy, working at liquid nitrogen temperatures on Si substrates. The achievement of quantum photon statistics up to T=80 K is directly proved by antibunching in the second order correlation function as measured with a H anbury Brown and Twiss interferometer.

  17. Range Verification Methods in Particle Therapy: Underlying Physics and Monte Carlo Modeling

    PubMed Central

    Kraan, Aafke Christine

    2015-01-01

    Hadron therapy allows for highly conformal dose distributions and better sparing of organs-at-risk, thanks to the characteristic dose deposition as function of depth. However, the quality of hadron therapy treatments is closely connected with the ability to predict and achieve a given beam range in the patient. Currently, uncertainties in particle range lead to the employment of safety margins, at the expense of treatment quality. Much research in particle therapy is therefore aimed at developing methods to verify the particle range in patients. Non-invasive in vivo monitoring of the particle range can be performed by detecting secondary radiation, emitted from the patient as a result of nuclear interactions of charged hadrons with tissue, including β+ emitters, prompt photons, and charged fragments. The correctness of the dose delivery can be verified by comparing measured and pre-calculated distributions of the secondary particles. The reliability of Monte Carlo (MC) predictions is a key issue. Correctly modeling the production of secondaries is a non-trivial task, because it involves nuclear physics interactions at energies, where no rigorous theories exist to describe them. The goal of this review is to provide a comprehensive overview of various aspects in modeling the physics processes for range verification with secondary particles produced in proton, carbon, and heavier ion irradiation. We discuss electromagnetic and nuclear interactions of charged hadrons in matter, which is followed by a summary of some widely used MC codes in hadron therapy. Then, we describe selected examples of how these codes have been validated and used in three range verification techniques: PET, prompt gamma, and charged particle detection. We include research studies and clinically applied methods. For each of the techniques, we point out advantages and disadvantages, as well as clinical challenges still to be addressed, focusing on MC simulation aspects. PMID:26217586

  18. TU-H-CAMPUS-TeP3-05: Evaluation of the Microscopic Dose Enhancement in the Nanoparticle-Enhanced Auger Therapy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sung, W; Jung, S; Ye, S

    Purpose: The aim of this study is to apply Monte Carlo simulations to investigate the nanoparticle dose enhancement for Auger therapy. Methods: Two nanoparticle fabrications were considered: nanoshell and nanosphere. In the first step, a single nanoparticle was irradiated with Auger emitters. The electrons were scored in a phase space at the outer surface of the nanoparticle with Geant4-Penelope. In the second step, the previously recorded phase space was used as a source and placed at the center of a cell-size water phantom. The nanoscale dose was evaluated in water around the nanoparticle with Geant4-DNA. The dose enhancement factor (DEF)more » is defined as the ratio of doses with and without nanoparticles. The nanoparticles were replaced by corresponding water nanoparticle with the same size and volume source which represents typical situation of Auger emitters without nanoparticle. Various sizes/materials of nanoparticles and isotopes were considered. Results: Nanoshell - Microscopic dose was increased up to 130% at 20 – 100 nm distances from the surface of Au-{sup 125}I nanoshell. However, dose at less than 20 nm distance was reduced due to absorbed low energy electrons in gold nanoshell. The amounts and regions of the dose enhancement were dependent on nanoshell size, materials, and isotopes. Nanosphere - The increased amounts of electrons up to 300% and reduced average energy with nanosphere were observed compared with water nanoparticle. We observed localized dose enhancement (up to a factor 3.6) in the immediate vicinity (< 50 nm) of Au-{sup 125} I nanosphere. The dose enhancement patterns vary according to nanosphere sizes and isotopes. Conclusion: We conclude that Auger therapy with nanoparticles can lead to change of electron energy spectrum and dose enhancements at certain range. The dose enhancement patterns vary according to nanoparticle sizes, materials, and isotopes. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP: Ministry of Science, ICT and Future Planning) (No. NRF-2013M2B2B1075776)« less

  19. Radiotoxicity of Gadolinium-148 and Radium-223 in Mouse Testes: Relative Biological Effectiveness of Alpha-Particle Emitters In Vivo

    PubMed Central

    Howell, Roger W.; Goddu, S. Murty; Narra, Venkat R.; Fisher, Darrell R.; Schenter, Robert E.; Rao, Dandamudi V.

    2012-01-01

    The biological effects of radionuclides that emit α particles are of considerable interest in view of their potential for therapy and their presence in the environment. The present work is a continuation of our ongoing effort to study the radiotoxicity of α-particle emitters in vivo using the survival of murine testicular sperm heads as the biological end point. Specifically, the relative biological effectiveness (RBE) of very low-energy α particles (3.2 MeV) emitted by 148Gd is investigated and determined to be 7.4 ± 2.4 when compared to the effects of acute external 120 kVp X rays. This datum, in conjunction with our earlier results for 210Po and 212Pb in equilibrium with its daughters, is used to revise and extend the range of validity of our previous RBE–energy relationship for α particles emitted by tissue-incorporated radionuclides. The new empirical relationship is given by RBEα = 9.14 − 0.510 Eα, where 3 < Eα < 9 MeV. The validity of this empirical relationship is tested by determining the RBE of the prolific α-particle emitter 223Ra (in equilibrium with its daughters) experimentally in the same biological model and comparing the value obtained experimentally with the predicted value. The resulting RBE values are 5.4 ± 0.9 and 5.6, respectively. This close agreement strongly supports the adequacy of the empirical RBE-Eα relationship to predict the biological effects of α-particle emitters in Vivo. PMID:9052681

  20. Ultra-bright emission from hexagonal boron nitride defects as a new platform for bio-imaging and bio-labelling

    NASA Astrophysics Data System (ADS)

    Elbadawi, Christopher; Tran, Trong Toan; Shimoni, Olga; Totonjian, Daniel; Lobo, Charlene J.; Grosso, Gabriele; Moon, Hyowan; Englund, Dirk R.; Ford, Michael J.; Aharonovich, Igor; Toth, Milos

    2016-12-01

    Bio-imaging requires robust ultra-bright probes without causing any toxicity to the cellular environment, maintain their stability and are chemically inert. In this work we present hexagonal boron nitride (hBN) nanoflakes which exhibit narrowband ultra-bright single photon emitters1. The emitters are optically stable at room temperature and under ambient environment. hBN has also been noted to be noncytotoxic and seen significant advances in functionalization with biomolecules2,3. We further demonstrate two methods of engineering this new range of extremely robust multicolour emitters across the visible and near infrared spectral ranges for large scale sensing and biolabeling applications.

  1. Design, conditioning, and performance of a high voltage, high brightness dc photoelectron gun with variable gap

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Maxson, Jared; Bazarov, Ivan; Dunham, Bruce

    2014-09-15

    A new high voltage photoemission gun has been constructed at Cornell University which features a segmented insulator and a movable anode, allowing the cathode-anode gap to be adjusted. In this work, we describe the gun's overall mechanical and high voltage design, the surface preparation of components, as well as the clean construction methods. We present high voltage conditioning data using a 50 mm cathode-anode gap, in which the conditioning voltage exceeds 500 kV, as well as at smaller gaps. Finally, we present simulated emittance results obtained from a genetic optimization scheme using voltage values based on the conditioning data. Thesemore » results indicate that for charges up to 100 pC, a 30 mm gap at 400 kV has equal or smaller 100% emittance than a 50 mm gap at 450 kV, and also a smaller core emittance, when placed as the source for the Cornell energy recovery linac photoinjector with bunch length constrained to be <3 ps rms. For 100 pC up to 0.5 nC charges, the 50 mm gap has larger core emittance than the 30 mm gap, but conversely smaller 100% emittance.« less

  2. Consequences of bounds on longitudinal emittance growth for the design of recirculating linear accelerators

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Berg, J. S.

    2015-05-03

    Recirculating linear accelerators (RLAs) are a cost-effective method for the acceleration of muons for a muon collider in energy ranges from a couple GeV to a few 10s of GeV. Muon beams generally have longitudinal emittances that are large for the RF frequency that is used, and it is important to limit the growth of that longitudinal emittance. This has particular consequences for the arc design of the RLAs. I estimate the longitudinal emittance growth in an RLA arising from the RF nonlinearity. Given an emittance growth limitation and other design parameters, one can then compute the maximum momentum compactionmore » in the arcs. I describe how to obtain an approximate arc design satisfying these requirements based on the deisgn in [1]. Longitudinal dynamics also determine the energy spread in the beam, and this has consequences on the transverse phase advance in the linac. This in turn has consequences for the arc design due to the need to match beta functions. I combine these considerations to discuss design parameters for the acceleration of muons for a collider in an RLA from 5 to 63 GeV.« less

  3. ELECTRON BEAM SHAPING AND ITS APPLICATIONS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Halavanau, Aliaksei

    Transverse and longitudinal electron beam shaping is a crucial part of high-brightness electron accelerator operations. In this dissertation, we report on the corresponding beam dynamics research conducted at Fermilab Accelerator Science and Technology facility (FAST) and Argonne Wakeeld Accelerator (AWA). We demonstrate an experimental method for spatial laser and electron beam shaping using microlens arrays (MLAs) at a photoinjector facility. Such a setup was built at AWA and resulted in transverse emittance reduction by a factor of 2. We present transverse emittance partitioning methods that were recently employed at FAST facility. A strongly coupled electron beam was generated in anmore » axial magnetic eld and accelerated in 1.3 GHz SRF cavities to 34 MeV. It was then decoupled in Round-To-Flat beam transformer and beams with emittance asymmetry ratio of 100 were generated. We introduce the new methods of measuring electron beam canonical angular momentum, beam transformer optimization and beam image analysis. We also describe a potential longitudinal space-charge amplier setup for FAST high-energy beamline. As an outcome, a broadband partially coherent radiation in the UV range could be generated.« less

  4. Self-sensing of temperature rises on light emitting diode based optrodes

    NASA Astrophysics Data System (ADS)

    Dehkhoda, Fahimeh; Soltan, Ahmed; Ponon, Nikhil; Jackson, Andrew; O'Neill, Anthony; Degenaar, Patrick

    2018-04-01

    Objective. This work presents a method to determine the surface temperature of microphotonic medical implants like LEDs. Our inventive step is to use the photonic emitter (LED) employed in an implantable device as its own sensor and develop readout circuitry to accurately determine the surface temperature of the device. Approach. There are two primary classes of applications where microphotonics could be used in implantable devices; opto-electrophysiology and fluorescence sensing. In such scenarios, intense light needs to be delivered to the target. As blue wavelengths are scattered strongly in tissue, such delivery needs to be either via optic fibres, two-photon approaches or through local emitters. In the latter case, as light emitters generate heat, there is a potential for probe surfaces to exceed the 2 °C regulatory. However, currently, there are no convenient mechanisms to monitor this in situ. Main results. We present the electronic control circuit and calibration method to monitor the surface temperature change of implantable optrode. The efficacy is demonstrated in air, saline, and brain. Significance. This paper, therefore, presents a method to utilize the light emitting diode as its own temperature sensor.

  5. Analysis of metabolic washout of positron emitters produced during carbon ion head and neck radiotherapy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Helmbrecht, Stephan; Enghardt, Wolfgang; Parodi, Katia

    2013-09-15

    Purpose: Particle Therapy Positron Emission Tomography (PT-PET) is a suitable method for verification of therapeutic dose delivery by measurements of irradiation-induced β{sup +}-activity. Due to metabolic processes in living tissue β{sup +}-emitters can be removed from the place of generation. This washout is a limiting factor for image quality. The purpose of this study is to investigate whether a washout model obtained by animal experiments is applicable to patient data.Methods: A model for the washout has been developed by Mizuno et al. [Phys. Med. Biol. 48(15), 2269–2281 (2003)] and Tomitani et al. [Phys. Med. Biol. 48(7), 875–889 (2003)]. It ismore » based upon measurements in a rabbit in living and dead conditions. This model was modified and applied to PET data acquired during the experimental therapy project at GSI Helmholtzzentrum für Schwerionenforschung Darmstadt, Germany. Three components are expected: A fast one with a half life of 2 s, a medium one in the range of 2–3 min, and a slow component of the order of 2–3 h. Ten patients were selected randomly for investigation of the fast component. To analyze the other two components, 12 one-of-a-kind measurements from a single volunteer patient are available.Results: A fast washout on the time scale of a few seconds was not observed in the patient data. The medium processes showed a mean half life of 155.7 ± 4.6 s. This is in the expected range. Fractions of the activity not influenced by the washout were found.Conclusions: On the time scale of an in-beam or in-room measurement only the medium-time washout processes play a remarkable role. A slow component may be neglected if the measurements do not exceed 20 min after the end of the irradiation. The fast component is not observed due to the low relative blood filled volume in the brain.« less

  6. Analytical and numerical calculation of the second-order moment of the beam using a capacitive pickup

    NASA Astrophysics Data System (ADS)

    Tsemo Kamga, Joel Alain; Müller, Wolfgang F. O.; Weiland, Thomas

    2016-04-01

    Beam emittance has particular importance in particle physics, because it provides information about the quality of the particle beam. There are many techniques for measuring the beam emittance, such as that proposed by Miller et al. [Report No. SLAC-PUB-3186, (A) (1983)]. This technique is based on determining the emittance by measuring the second-order moment of the beam using quadrupole pickups consisting of four symmetrical electrodes placed around the beam pipe at 90° intervals, respectively. Based on Miller's approach, two signal processing methods are generally used to get the quadrupole moment of the beam, namely the difference over sum and the log ratio [P. Li et al., IEEE Nuclear Science Symposium Conference Record, N24-404, 2007, pp. 1675-1678] methods. However, these traditional methods provide results with a good accuracy only for a well centered beam. The method presented in this paper, which starts with Miller's approach, considerably reduces the impact of the dipole signal on the quadrupole moment measurement for both small and large values of the beam position. Furthermore, a methodology for the numerical determination of the sensitivity of quadrupole pickups will be presented.

  7. Enhancing Three-dimensional Movement Control System for Assemblies of Machine-Building Facilities

    NASA Astrophysics Data System (ADS)

    Kuzyakov, O. N.; Andreeva, M. A.

    2018-01-01

    Aspects of enhancing three-dimensional movement control system are given in the paper. Such system is to be used while controlling assemblies of machine-building facilities, which is a relevant issue. The base of the system known is three-dimensional movement control device with optical principle of action. The device consists of multi point light emitter and light receiver matrix. The processing of signals is enhanced to increase accuracy of measurements by switching from discrete to analog signals. Light receiver matrix is divided into four areas, and the output value of each light emitter in each matrix area is proportional to its luminance level. Thus, determing output electric signal value of each light emitter in corresponding area leads to determing position of multipoint light emitter and position of object tracked. This is done by using Case-based reasoning method, the precedent in which is described as integral signal value of each matrix area, coordinates of light receivers, which luminance level is high, and decision to be made in this situation.

  8. Lattice and beam optics design for suppression of CSR-induced emittance growth at the KEK-ERL test facility

    NASA Astrophysics Data System (ADS)

    Shimada, M.; Yokoya, K.; Suwada, T.; Enomoto, A.

    2007-06-01

    The lattice and beam optics of the arc section of the KEK-ERL test facility, having an energy of 200 MeV, were optimized to efficiently suppress emittance growth based on a simulation using a particle-tracking method taking coherent synchrotron radiation effects into account. The lattice optimization in the arc section was performed under two conditions: a high-current mode with a bunch charge of 76.9 pC without bunch compression, and a short-bunch mode with bunch compression, producing a final bunch length of around 0.1 ps. The simulation results showed that, in the high-current mode, emittance growth was efficiently suppressed by keeping a root-mean-square (rms) bunch length of 1 ps at a bunch charge of 76.9 pC, and in the short-bunch mode, emittance growth was kept within permissible limits with a maximum allowable bunch charge of 23.1 pC at an rms bunch length of 0.1 ps.

  9. Two-color ionization injection using a plasma beatwave accelerator

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schroeder, C. B.; Benedetti, C.; Esarey, E.

    Two-color laser ionization injection is a method to generate ultra-low emittance (sub-100 nm transverse normalized emittance) beams in a laser-driven plasma accelerator. A plasma beatwave accelerator is proposed to drive the plasma wave for ionization injection, where the beating of the lasers effectively produces a train of long-wavelength pulses. The plasma beatwave accelerator excites a large amplitude plasma wave with low peak laser electric fields, leaving atomically-bound electrons with low ionization potential. A short-wavelength, low-amplitude ionization injection laser pulse (with a small ponderomotive force and large peak electric field) is used to ionize the remaining bound electrons at a wakemore » phase suitable for trapping, generating an ultra-low emittance electron beam that is accelerated in the plasma wave. Using a plasma beatwave accelerator for wakefield excitation, compared to short-pulse wakefield excitation, allows for a lower amplitude injection laser pulse and, hence, a lower emittance beam may be generated.« less

  10. On the Ionization and Ion Transmission Efficiencies of Different ESI-MS Interfaces

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cox, Jonathan T.; Marginean, Ioan; Smith, Richard D.

    2014-09-30

    It is well known that the achievable sensitivity of electrospray ionization mass spectrometry (ESI-MS) is largely determined by the ionization efficiency in the ESI source and ion transmission efficiency through the ESI-MS interface. In this report we systematically study the ion transmission and ionization efficiencies in different ESI-MS interface configurations. The configurations under investigation include a single emitter/single inlet capillary, single emitter/multi-inlet capillary, and a subambient pressure ionization with nanoelectrospray (SPIN) MS interfaces with a single emitter and an emitter array, respectively. We present an effective method to evaluate the overall ion utilization efficiency of an ESI-MS interface by measuringmore » the total gas phase ion current transmitted through the interface and correlating it to the observed ion abundance measured in the corresponding mass spectrum. Our experimental results suggest that the overall ion utilization efficiency in the SPIN-MS interface configurations is better than that in the inlet capillary based ESI-MS interface configurations.« less

  11. Two-color ionization injection using a plasma beatwave accelerator

    DOE PAGES

    Schroeder, C. B.; Benedetti, C.; Esarey, E.; ...

    2018-01-10

    Two-color laser ionization injection is a method to generate ultra-low emittance (sub-100 nm transverse normalized emittance) beams in a laser-driven plasma accelerator. A plasma beatwave accelerator is proposed to drive the plasma wave for ionization injection, where the beating of the lasers effectively produces a train of long-wavelength pulses. The plasma beatwave accelerator excites a large amplitude plasma wave with low peak laser electric fields, leaving atomically-bound electrons with low ionization potential. A short-wavelength, low-amplitude ionization injection laser pulse (with a small ponderomotive force and large peak electric field) is used to ionize the remaining bound electrons at a wakemore » phase suitable for trapping, generating an ultra-low emittance electron beam that is accelerated in the plasma wave. Using a plasma beatwave accelerator for wakefield excitation, compared to short-pulse wakefield excitation, allows for a lower amplitude injection laser pulse and, hence, a lower emittance beam may be generated.« less

  12. Method and apparatus utilizing ionizing and microwave radiation for saturation determination of water, oil and a gas in a core sample

    DOEpatents

    Maerefat, Nicida L.; Parmeswar, Ravi; Brinkmeyer, Alan D.; Honarpour, Mehdi

    1994-01-01

    A system for determining the relative permeabilities of gas, water and oil in a core sample has a microwave emitter/detector subsystem and an X-ray emitter/detector subsystem. A core holder positions the core sample between microwave absorbers which prevent diffracted microwaves from reaching a microwave detector where they would reduce the signal-to-noise ratio of the microwave measurements. The microwave emitter/detector subsystem and the X-ray emitter/detector subsystem each have linear calibration characteristics, allowing one subsystem to be calibrated with respect to the other subsystem. The dynamic range of microwave measurements is extended through the use of adjustable attenuators. This also facilitates the use of core samples with wide diameters. The stratification characteristics of the fluids may be observed with a windowed cell separator at the outlet of the core sample. The condensation of heavy hydrocarbon gas and the dynamic characteristics of the fluids are observed with a sight glass at the outlet of the core sample.

  13. Out-of-core Evaluations of Uranium Nitride-fueled Converters

    NASA Technical Reports Server (NTRS)

    Shimada, K.

    1972-01-01

    Two uranium nitride fueled converters were tested parametrically for their initial characterization and are currently being life-tested out of core. Test method being employed for the parametric and the diagnostic measurements during the life tests, and test results are presented. One converter with a rhenium emitter had an initial output power density of 6.9 W/ sq cm at the black body emitter temperature of 1900 K. The power density remained unchanged for the first 1000 hr of life test but degraded nearly 50% percent during the following 1000 hr. Electrode work function measurements indicated that the uranium fuel was diffusing out of the emitter clad of 0.635 mm. The other converter with a tungsten emitter had an initial output power density of 2.2 W/ sq cm at 1900 K with a power density of 3.9 W/sq cm at 4300 h. The power density suddenly degraded within 20 hr to practically zero output at 4735 hr.

  14. Monolithic multinozzle emitters for nanoelectrospray mass spectrometry

    DOEpatents

    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.

  15. Control of fluorescence in quantum emitter and metallic nanoshell hybrids for medical applications

    NASA Astrophysics Data System (ADS)

    Singh, Mahi R.; Guo, Jiaohan; J. Cid, José M.; De Hoyos Martinez, Jesús E.

    2017-03-01

    We study the light emission from a quantum emitter and double metallic nanoshell hybrid systems. Quantum emitters act as local sources which transmit their light efficiently due to a double nanoshell near field. The double nanoshell consists of a dielectric core and two outer nanoshells. The first nanoshell is made of a metal, and the second spacer nanoshell is made of a dielectric material or human serum albumin. We have calculated the fluorescence emission for a quantum emitter-double nanoshell hybrid when it is injected in an animal or a human body. Surface plasmon polariton resonances in the double nanoshell are calculated using Maxwell's equations in the quasi-static approximation, and the fluorescence emission is evaluated using the density matrix method in the presence of dipole-dipole interactions. We have compared our theory with two fluorescence experiments in hybrid systems in which the quantum emitter is Indocyanine Green or infrared fluorescent molecules. The outer spacer nanoshell of double metallic nanoshells consists of silica and human serum albumin with variable thicknesses. Our theory explains the enhancement of fluorescence spectra in both experiments. We find that the thickness of the spacer nanoshell layer increases the enhancement when the fluorescence decreases. The enhancement of the fluorescence depends on the type of quantum emitter, spacer layer, and double nanoshell. We also found that the peak of the fluorescence spectrum can be shifted by changing the shape and the size of the nanoshell. The fluorescence spectra can be switched from one peak to two peaks by removing the degeneracy of excitonic states in the quantum emitter. Hence, using these properties, one can use these hybrids as sensing and switching devices for applications in medicine.

  16. Fiber-optical method of pyrometric measurement of melts temperature

    NASA Astrophysics Data System (ADS)

    Zakharenko, V. A.; Veprikova, Ya R.

    2018-01-01

    There is a scientific problem of non-contact measurement of the temperature of metal melts now. The problem is related to the need to achieve the specified measurement errors in conditions of uncertainty of the blackness coefficients of the radiating surfaces. The aim of this work is to substantiate the new method of measurement in which the influence of the blackness coefficient is eliminated. The task consisted in calculating the design and material of special crucible placed in the molten metal, which is an emitter in the form of blackbody (BB). The methods are based on the classical concepts of thermal radiation and calculations based on the Planck function. To solve the problem, the geometry of the crucible was calculated on the basis of the Goofy method which forms the emitter of a blackbody at the immersed in the melt. The paper describes the pyrometric device based on fiber optic pyrometer for temperature measurement of melts, which implements the proposed method of measurement using a special crucible. The emitter is formed by the melt in this crucible, the temperature within which is measured by means of fiber optic pyrometer. Based on the results of experimental studies, the radiation coefficient ε‧ > 0.999, which confirms the theoretical and computational justification is given in the article

  17. Potential clinical impact of laser-accelerated beams in cancer ion therapy

    NASA Astrophysics Data System (ADS)

    Obcemea, Ceferino

    2016-09-01

    In this article, I present three advantages of plasma-accelerated ion beams for cancer therapy. I discuss how: 1. low-emittance and well-collimated beams are advantageous in proximal normal tissue-sparing; 2. highly-peaked quasi-monoenergetic beams are ideal for fast energy selection and switching in Pencil Beam Scanning (PBS) as a treatment delivery; 3. high fluence and ultra-short pulse delivery produce collective excitations in the medium and enhance the stopping power. This in turn produces denser ionization track signatures (spurs, blobs, etc.) in target tumors, higher linear energy transfer, higher Bragg peak, and higher radiobiological effectiveness at the micro-level.

  18. Association of Far-Infrared Radiation Therapy and Ankle-Brachial Index of Patients on Hemodialysis with Peripheral Artery Occlusive Disease

    PubMed Central

    Chen, Szu-Chia; Lee, Mei-Yueh; Huang, Jiun-Chi; Kuo, I-Ching; Mai, Hsiu-Chin; Kuo, Po-Lin; Chang, Jer-Ming; Hwang, Shang-Jyh; Chen, Hung-Chun

    2016-01-01

    Background and Aim: The ankle-brachial index (ABI) is recognized to be a good marker for atherosclerosis, and is useful in the diagnosis of peripheral artery occlusive disease (PAOD) which is prevalent among patients on hemodialysis (HD). Methods: This randomized trial aimed to evaluate the effect of far-infrared radiation (FIR) therapy on ABI in HD patients with PAOD. PAOD was defined as patients with ABI < 0.95. One hundred and eight HD patients were enrolled, including 50 in the control group and 58 in the FIR group. A WS TY101 FIR emitter was applied for 40 minutes during each HD session, three times per week for six months. The ABI was measured before and after the FIR therapy. Results: Regardless of FIR therapy, the bilateral ABI decreased (in the FIR group, left: 0.88±0.22 to 0.85±0.24, p = 0.188; right: 0.92±0.20 to 0.90±0.23, p = 0.372; in control group, left: 0.91±0.23 to 0.88±0.21, p = 0144; right: 0.93±0.17 to 0.89±0.21, p = 0.082). Multivariate logistic analysis of the FIR group revealed that high uric acid (odds ratio [OR]: 2.335; 95% confidence interval [CI]: 1.117-4.882; p=0.024) and aspirin use (OR: 16.463; 95% CI: 1.787-151.638; p=0.013) were independently associated with increased bilateral ABI after FIR therapy. Conclusions: This study demonstrates that ABI is not increased after FIR therapy in HD patients with PAOD. However, in the FIR group, patients with higher uric acid level or those who used aspirin have increased bilateral ABI after FIR therapy. PMID:27994503

  19. Noninterceptive transverse emittance measurements using BPM for Chinese ADS R&D project

    NASA Astrophysics Data System (ADS)

    Wang, Zhi-Jun; Feng, Chi; He, Yuan; Dou, Weiping; Tao, Yue; Chen, Wei-long; Jia, Huan; Liu, Shu-hui; Wang, Wang-sheng; Zhang, Yong; Wu, Jian-qiang; Zhang, Sheng-hu; Zhang, X. L.

    2016-04-01

    The noninterceptive four-dimensional transverse emittance measurements are essential for commissioning the high power continue-wave (CW) proton linacs as well as their operations. The conventional emittance measuring devices such as slits and wire scanners are not well suited under these conditions due to sure beam damages. Therefore, the method of using noninterceptive Beam Position Monitor (BPM) is developed and demonstrated on Injector Scheme II at the Chinese Accelerator Driven Sub-critical System (China-ADS) proofing facility inside Institute of Modern Physics (IMP) [1]. The results of measurements are in good agreements with wire scanners and slits at low duty-factor pulsed (LDFP) beam. In this paper, the detailed experiment designs, data analysis and result benchmarking are presented.

  20. Methods and apparatus for producing and storing positrons and protons

    DOEpatents

    Akers, Douglas W [Idaho Falls, ID

    2010-07-06

    Apparatus for producing and storing positrons may include a trap that defines an interior chamber therein and that contains an electric field and a magnetic field. The trap may further include a source material that includes atoms that, when activated by photon bombardment, become positron emitters to produce positrons. The trap may also include a moderator positioned adjacent the source material. A photon source is positioned adjacent the trap so that photons produced by the photon source bombard the source material to produce the positron emitters. Positrons from the positron emitters and moderated positrons from the moderator are confined within the interior chamber of the trap by the electric and magnetic fields. Apparatus for producing and storing protons are also disclosed.

  1. Beam Conditioning for FELs: Consequences and Methods

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wolski, Andrzej; Penn, Gregory; Sessler, Andrew

    2003-10-09

    The consequences of beam conditioning in four example cases (VISA, a Soft X-Ray FEL, LCLS and a ''Greenfield'' FEL) are examined. It is shown that in emittance limited cases, proper conditioning reduces sensitivity to the transverse emittance, and allows stronger focusing in the undulator. Simulations show higher saturation power, with gain lengths reduced up to a factor of two. The beam dynamics in a general conditioning system are studied, with ''matching conditions'' derived for achieving conditioning without growth in effective emittance. Various conditioners are considered, and expressions derived for the amount of conditioning provided in each case when the matchingmore » conditions are satisfied. We discuss the prospects for conditioners based on laser and plasma systems.« less

  2. Apparatus for and method of monitoring for breached fuel elements

    DOEpatents

    Gross, K.C.; Strain, R.V.

    1981-04-28

    This invention teaches improved apparatus for the method of detecting a breach in cladded fuel used in a nuclear reactor. The detector apparatus uses a separate bypass loop for conveying part of the reactor coolant away from the core, and at least three separate delayed-neutron detectors mounted proximate this detector loop. The detectors are spaced apart so that the coolant flow time from the core to each detector is different, and these differences are known. The delayed-neutron activity at the detectors is a function of the delay time after the reaction in the fuel until the coolant carrying the delayed-neutron emitter passes the respective detector. This time delay is broken down into separate components including an isotopic holdup time required for the emitter to move through the fuel from the reaction to the coolant at the breach, and two transit times required for the emitter now in the coolant to flow from the breach to the detector loop and then via the loop to the detector.

  3. Nanospray mass spectrometry with indirect conductive graphite coating.

    PubMed

    Viberg, Peter; Nilsson, Staffan; Skog, Kerstin

    2004-07-15

    An easy and cost-effective method to manufacture a robust conductive graphite coating for nanospray mass spectrometry (nESI-MS) and capillary electrophoresis (CE)-nESI-MS is described. The method involves graphite coating of a tube sleeve, into which the nESI emitter is inserted and connected to a transfer capillary, instead of coating the actual emitter. The coating, made of graphite from a pencil and epoxy glue, was stable over long periods of use (>80 h) and showed excellent resistance toward various solvents. Stable electrospray was achieved in the investigated flow range (150-900 nL x min(-)(1)), and salbutamol, diphenhydramine, and nortriptyline (M(w): 239-263 g x mol(-)(1)) were detected in the nanomole per liter range during continuous pumping. CE-nESI-MS analysis gave excellent signal-to-noise ratios for 100-fmol injections. The technique allows simple exchange of the nESI emitter to suit a specific flow rate, and it minimizes risk of corona discharge.

  4. Reappraisal of solid selective emitters

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.

    1990-01-01

    New rare earth oxide emitters show greater efficiency than previous emitters. As a result, based on a simple model the efficiency of these emitters was calculated. Results indicate that the emission band of the selective emitter must be at relatively low energy (less than or equal to .52 eV) to obtain maximum efficiency at moderate emitter temperatures (less than or equal to 1500 K). Thus low bandgap energy PV materials are required to obtain an efficient thermophotovoltaic (TPV) system. Of the 4 specific rare earths (Nd, Ho, Er, Yb) studied Ho has the largest efficiency at moderate temperatures (72 percent at 1500 K). A comparison was made between a selective emitter TPV system and a TPV system that uses a thermal emitter plus a band pass filter to make the thermal emitter behave like a selective emitter. Results of the comparison indicate that only for very optimistic filter and thermal emitter properties will the filter TPV system have a greater efficiency than the selective emitter system.

  5. SDF technology in location and navigation procedures: a survey of applications

    NASA Astrophysics Data System (ADS)

    Kelner, Jan M.; Ziółkowski, Cezary

    2017-04-01

    The basis for development the Doppler location method, also called the signal Doppler frequency (SDF) method or technology is the analytical solution of the wave equation for a mobile source. This paper presents an overview of the simulations, numerical analysis and empirical studies of the possibilities and the range of SDF method applications. In the paper, the various applications from numerous publications are collected and described. They mainly focus on the use of SDF method in: emitter positioning, electronic warfare, crisis management, search and rescue, navigation. The developed method is characterized by an innovative, unique property among other location methods, because it allows the simultaneous location of the many radio emitters. Moreover, this is the first method based on the Doppler effect, which allows positioning of transmitters, using a single mobile platform. In the paper, the results of the using SDF method by the other teams are also presented.

  6. Rare Earth Garnet Selective Emitter

    NASA Technical Reports Server (NTRS)

    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 impurities, in the development of solid state laser crystals. Doping, dependent on the particular ion and crystal structure, may be as high as 100 at. % (complete substitution of yttrium ion with the rare earth ion). These materials have high melting points, 1940 C for YAG (Yttrium Aluminum Garnet), and low emissivity in the near infrared making them excellent candidates for a thin film selective emitter. As previously stated, the spectral emittance of a rare earth emitter is characterized by one or more well defined emission bands. Outside the emission band the emittance(absorptance) is much lower. Therefore, it is expected that emission outside the band for a thin film selective emitter will be dominated by the emitter substrate. For an efficient emitter (power in the emission band/total emitted power) the substrate must have low emittance, epsilon(sub S). This paper presents normal spectral emittance, epsilon(sub lambda), measurements of holmium(Ho) and erbium (Er) doped YAG thin film selective emitters at (1500 K), and compares those results with the theoretical spectral emittance.

  7. Velocity-Map Imaging for Emittance Characterization of Multiphoton Electron Emission from a Gold Surface

    NASA Astrophysics Data System (ADS)

    Ye, Hong; Trippel, Sebastian; Di Fraia, Michele; Fallahi, Arya; Mücke, Oliver D.; Kärtner, Franz X.; Küpper, Jochen

    2018-04-01

    A velocity-map-imaging spectrometer is demonstrated to characterize the normalized emittance (root-mean-square, rms) of photoemitted electron bunches. Both the two-dimensional spatial distribution and the projected velocity distribution images of photoemitted electrons are recorded by the detection system and analyzed to obtain the normalized emittance (rms). With the presented distribution function of the electron photoemission angles, a mathematical method is implemented to reconstruct the three-dimensional velocity distribution. As a first example, multiphoton emission from a planar Au surface is studied via irradiation at a glancing angle by intense 45-fs laser pulses at a central wavelength of 800 nm. The reconstructed energy distribution agrees very well with the Berglund-Spicer theory of photoemission. The normalized emittance (rms) of the intrinsic electron bunch is characterized to be 128 and 14 nm rad in the X and Y directions, respectively. The demonstrated imaging spectrometer has the ability to characterize the normalized emittance (rms) in a few minutes with a fine energy resolution of 0.2 meV in the image center and will, thereby, foster the further development of x-ray free-electron-laser injectors and ultrafast electron diffraction, and it opens up opportunities for studying correlated electron emission from surfaces and vacuum nanoelectronic devices.

  8. Chemical regeneration of emitter surface increases thermionic diode life

    NASA Technical Reports Server (NTRS)

    Breiteieser, R.

    1966-01-01

    Chemical regeneration of sublimated emitter electrode increases the operating efficiency and life of thermionic diodes. A gas which forms chemical compounds with the sublimated emitter material is introduced into the space between the emitter and the collector. The compounds migrate to the emitter where they decompose and redeposit the emitter material.

  9. Processing digital images and calculation of beam emittance (pepper-pot method for the Krion source)

    NASA Astrophysics Data System (ADS)

    Alexandrov, V. S.; Donets, E. E.; Nyukhalova, E. V.; Kaminsky, A. K.; Sedykh, S. N.; Tuzikov, A. V.; Philippov, A. V.

    2016-12-01

    Programs for the pre-processing of photographs of beam images on the mask based on Wolfram Mathematica and Origin software are described. Angles of rotation around the axis and in the vertical plane are taken into account in the generation of the file with image coordinates. Results of the emittance calculation by the Pep_emit program written in Visual Basic using the generated file in the test mode are presented.

  10. A Method for Eliminating Beam Steering Error for the Modulated Absorption-Emission Thermometry Technique

    DTIC Science & Technology

    2014-01-01

    broadened and merged. It is also suitable for environments where broadband emitters such as soot are present. Radiometric measurements in general can be...emitters such as soot are present. Radiometric measurements in general can be made with very high accuracy. The international temperature scale (ITS...by a fitting to a model. In the case of sooting flames, the emissivity is a result of the nearly black absorption and emission features of soot

  11. Use of probabilistic neural networks for emitter correlation

    NASA Astrophysics Data System (ADS)

    Maloney, P. S.

    1990-08-01

    The Probabilistic Neural Network (PNN) as described by Specht''3 has been successfully applied to a number of emitter correlation problems involving operational data for training and testing of the neural net work. The PNN has been found to be a reliable classification tool for determining emitter type or even identifying specific emitter platforms given appropriate representative data sets for training con sisting only of parametric data from electronic intelligence (ELINT) reports. Four separate feasibility studies have been conducted to prove the usefulness of PNN in this application area: . Hull-to-emitter correlation (HULTEC) for identification of seagoing emitter platforms . Identification of landbased emitters from airborne sensors . Pulse sorting according to emitter of origin . Emitter typing based on a dynamically learning neural network. 1 .

  12. RF System for the MICE Demonstration of Ionisation Cooling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ronald, K.; et al.

    2017-04-01

    Muon accelerators offer an attractive option for a range of future particle physics experiments. They can enable high energy (TeV+) high energy lepton colliders whilst mitigating the difficulty of synchrotron losses, and can provide intense beams of neutrinos for fundamental physics experiments investigating the physics of flavor. The method of production of muon beams results in high beam emittance which must be reduced for efficient acceleration. Conventional emittance control schemes take too long, given the very short (2.2 microsecond) rest lifetime of the muon. Ionisation cooling offers a much faster approach to reducing particle emittance, and the international MICE collaborationmore » aims to demonstrate this technique for the first time. This paper will present the MICE RF system and its role in the context of the overall experiment.« less

  13. Heavy doping effects in high efficiency silicon solar cells

    NASA Technical Reports Server (NTRS)

    Lindholm, F. A.; Neugroschel, A.

    1986-01-01

    The temperature dependence of the emitter saturation current for bipolar devices was studied by varying the surface recombination velocity at the emitter surface. From this dependence, the value was derived for bandgap narrowing that is in better agreement with other determinations that were obtained from the temperature dependence measure on devices with ohmic contacts. Results of the first direct measurement of the minority-carrier transit time in a transparent heavily doped emitter layer were reported. The value was obtained by a high-frequency conductance method recently developed and used for doped Si. Experimental evidence is presented for significantly greater charge storage in highly excited silicon near room temperature than conventional theory would predict. These data are compared with various data for delta E sub G in heavily doped silicon.

  14. Minimization of three-dimensional beam emittance growth in rare-isotope accelerator

    NASA Astrophysics Data System (ADS)

    Oh, B. H.; Yoon, M.

    2016-12-01

    In this paper, we describe a research to minimize the three-dimensional (3D) emittance growth (EG) in the RAON accelerator, a heavy ion accelerator currently being developed in Korea to produce various rare isotopes. The emittance minimization is performed using the multi-objective genetic algorithm and the simplex method. We use them to analyze the driver linac for the in-flight fragmentation separator of the RAON facility and show that redesign of the 90-degree bending section of the RAON accelerator together with adjustment of optics in the upstream and downstream superconducting linacs can limit the 3D EG to 20 % in the entire region of the driver linac. Effects of various magnet and rf accelerating cavity errors on the beam-EG are also discussed.

  15. A chip-scale, telecommunications-band frequency conversion interface for quantum emitters.

    PubMed

    Agha, Imad; Ates, Serkan; Davanço, Marcelo; Srinivasan, Kartik

    2013-09-09

    We describe a chip-scale, telecommunications-band frequency conversion interface designed for low-noise operation at wavelengths desirable for common single photon emitters. Four-wave-mixing Bragg scattering in silicon nitride waveguides is used to demonstrate frequency upconversion and downconversion between the 980 nm and 1550 nm wavelength regions, with signal-to-background levels > 10 and conversion efficiency of ≈ -60 dB at low continuous wave input pump powers (< 50 mW). Finite element simulations and the split-step Fourier method indicate that increased input powers of ≈ 10 W (produced by amplified nanosecond pulses, for example) will result in a conversion efficiency > 25 % in existing geometries. Finally, we present waveguide designs that can be used to connect shorter wavelength (637 nm to 852 nm) quantum emitters with 1550 nm.

  16. Observation of High Transformer Ratio of Shaped Bunch Generated by an Emittance-Exchange Beam Line.

    PubMed

    Gao, Q; Ha, G; Jing, C; Antipov, S P; Power, J G; Conde, M; Gai, W; Chen, H; Shi, J; Wisniewski, E E; Doran, D S; Liu, W; Whiteford, C E; Zholents, A; Piot, P; Baturin, S S

    2018-03-16

    Collinear wakefield acceleration has been long established as a method capable of generating ultrahigh acceleration gradients. Because of the success on this front, recently, more efforts have shifted towards developing methods to raise the transformer ratio (TR). This figure of merit is defined as the ratio of the peak acceleration field behind the drive bunch to the peak deceleration field inside the drive bunch. TR is always less than 2 for temporally symmetric drive bunch distributions and therefore recent efforts have focused on generating asymmetric distributions to overcome this limitation. In this Letter, we report on using the emittance-exchange method to generate a shaped drive bunch to experimentally demonstrate a TR≈5 in a dielectric wakefield accelerator.

  17. Phase control and fast start-up of a magnetron using modulation of an addressable faceted cathode

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Browning, J., E-mail: JimBrowning@BoiseState.edu; Fernandez-Gutierrez, S.; Lin, M. C.

    The use of an addressable, faceted cathode has been proposed as a method of modulating current injection in a magnetron to improve performance and control phase. To implement the controllable electron emission, five-sided and ten-sided faceted planar cathodes employing gated field emitters are considered as these emitters could be fabricated on flat substrates. For demonstration, the conformal finite-difference time-domain particle-in-cell simulation, as implemented in VORPAL, has been used to model a ten-cavity, rising sun magnetron using the modulated current sources and benchmarked against a typical continuous current source. For the modulated, ten-sided faceted cathode case, the electrons are injected frommore » three emitter elements on each of the ten facets. Each emitter is turned ON and OFF in sequence at the oscillating frequency with five emitters ON at one time to drive the five electron spokes of the π-mode. The emitter duty cycle is then 1/6th the Radio-Frequency (RF) period. Simulations show a fast start-up time as low as 35 ns for the modulated case compared to 100 ns for the continuous current cases. Analysis of the RF phase using the electron spoke locations and the RF magnetic field components shows that the phase is controlled for the modulated case while it is random, as typical, for the continuous current case. Active phase control during oscillation was demonstrated by shifting the phase of the electron injection 180° after oscillations started. The 180° phase shift time was approximately 25 RF cycles.« less

  18. High temperature bias line stabilized current sources

    DOEpatents

    Patterson, III, Raymond B.

    1984-01-01

    A compensation device for the base of emitter follower configured bipolar transistors becoming operable at elevated temperatures including a bipolar transistor of a geometry of not more than half the geometry of the bipolar emitter follower having its collector connected to the base of the emitter follower and its base and emitter connected together and to the emitter of the emitter follower.

  19. High temperature bias line stabilized current sources

    DOEpatents

    Patterson, R.B. III.

    1984-09-11

    A compensation device for the base of emitter follower configured bipolar transistors becoming operable at elevated temperatures including a bipolar transistor of a geometry of not more than half the geometry of the bipolar emitter follower having its collector connected to the base of the emitter follower and its base and emitter connected together and to the emitter of the emitter follower. 1 fig.

  20. Intrinsic beam emittance of laser-accelerated electrons measured by x-ray spectroscopic imaging.

    PubMed

    Golovin, G; Banerjee, S; Liu, C; Chen, S; Zhang, J; Zhao, B; Zhang, P; Veale, M; Wilson, M; Seller, P; Umstadter, D

    2016-04-19

    The recent combination of ultra-intense lasers and laser-accelerated electron beams is enabling the development of a new generation of compact x-ray light sources, the coherence of which depends directly on electron beam emittance. Although the emittance of accelerated electron beams can be low, it can grow due to the effects of space charge during free-space propagation. Direct experimental measurement of this important property is complicated by micron-scale beam sizes, and the presence of intense fields at the location where space charge acts. Reported here is a novel, non-destructive, single-shot method that overcame this problem. It employed an intense laser probe pulse, and spectroscopic imaging of the inverse-Compton scattered x-rays, allowing measurement of an ultra-low value for the normalized transverse emittance, 0.15 (±0.06) π mm mrad, as well as study of its subsequent growth upon exiting the accelerator. The technique and results are critical for designing multi-stage laser-wakefield accelerators, and generating high-brightness, spatially coherent x-rays.

  1. Calculation of day and night emittance values

    NASA Technical Reports Server (NTRS)

    Kahle, Anne B.

    1986-01-01

    In July 1983, the Thermal Infrared Multispectral Scanner (TIMS) was flown over Death Valley, California on both a midday and predawn flight within a two-day period. The availability of calibrated digital data permitted the calculation of day and night surface temperature and surface spectral emittance. Image processing of the data included panorama correction and calibration to radiance using the on-board black bodies and the measured spectral response of each channel. Scene-dependent isolated-point noise due to bit drops, was located by its relatively discontinuous values and replaced by the average of the surrounding data values. A method was developed in order to separate the spectral and temperature information contained in the TIMS data. Night and day data sets were processed. The TIMS is unique in allowing collection of both spectral emittance and thermal information in digital format with the same airborne scanner. For the first time it was possible to produce day and night emittance images of the same area, coregistered. These data add to an understanding of the physical basis for the discrimination of difference in surface materials afforded by TIMS.

  2. Intrinsic beam emittance of laser-accelerated electrons measured by x-ray spectroscopic imaging

    DOE PAGES

    Golovin, G.; Banerjee, S.; Liu, C.; ...

    2016-04-19

    Here, the recent combination of ultra-intense lasers and laser-accelerated electron beams is enabling the development of a new generation of compact x-ray light sources, the coherence of which depends directly on electron beam emittance. Although the emittance of accelerated electron beams can be low, it can grow due to the effects of space charge during free-space propagation. Direct experimental measurement of this important property is complicated by micron-scale beam sizes, and the presence of intense fields at the location where space charge acts. Reported here is a novel, non-destructive, single-shot method that overcame this problem. It employed an intense lasermore » probe pulse, and spectroscopic imaging of the inverse-Compton scattered x-rays, allowing measurement of an ultra-low value for the normalized transverse emittance, 0.15 (±0.06) π mm mrad, as well as study of its subsequent growth upon exiting the accelerator. The technique and results are critical for designing multi-stage laser-wakefield accelerators, and generating high-brightness, spatially coherent x-rays.« less

  3. Method and apparatus utilizing ionizing and microwave radiation for saturation determination of water, oil and a gas in a core sample

    DOEpatents

    Maerefat, N.L.; Parmeswar, R.; Brinkmeyer, A.D.; Honarpour, M.

    1994-08-23

    A system is described for determining the relative permeabilities of gas, water and oil in a core sample has a microwave emitter/detector subsystem and an X-ray emitter/detector subsystem. A core holder positions the core sample between microwave absorbers which prevent diffracted microwaves from reaching a microwave detector where they would reduce the signal-to-noise ratio of the microwave measurements. The microwave emitter/detector subsystem and the X-ray emitter/detector subsystem each have linear calibration characteristics, allowing one subsystem to be calibrated with respect to the other subsystem. The dynamic range of microwave measurements is extended through the use of adjustable attenuators. This also facilitates the use of core samples with wide diameters. The stratification characteristics of the fluids may be observed with a windowed cell separator at the outlet of the core sample. The condensation of heavy hydrocarbon gas and the dynamic characteristics of the fluids are observed with a sight glass at the outlet of the core sample. 11 figs.

  4. Use of cyclotrons in medicine

    NASA Astrophysics Data System (ADS)

    Qaim, S. M.

    2004-10-01

    Cyclotrons are versatile ion-accelerating machines which find many applications in medicine. In this short review their use in hadron therapy is briefly discussed. Proton therapy is gaining significance because of its capability to treat deep-lying tumours. A strong area of application of cyclotrons involves the production of short-lived neutron deficient radiotracers for use in emission tomography, especially positron emission tomography. This fast and quantitative in vivo diagnostic technique is being increasingly used in neurology, cardiology and oncology. Besides routine patient care, considerable interdisciplinary work on development of new positron emitters is under way. A short account of those efforts is given. The use of cyclotrons in the production of radionuclides for internal radiotherapy is also briefly described.

  5. Quantifying, Assessing, and Mitigating Methane Emissions from Super-emitters in the Oil and Gas Supply Chain

    NASA Astrophysics Data System (ADS)

    Lyon, David Richard

    Methane emissions from the oil and gas (O&G) supply chain reduce potential climate benefits of natural gas as a replacement for other fossil fuels that emit more carbon dioxide per energy produced. O&G facilities have skewed emission rate distributions with a small fraction of sites contributing the majority of emissions. Knowledge of the identity and cause of these high emission facilities, referred to as super-emitters or fat-tail sources, is critical for reducing supply chain emissions. This dissertation addresses the quantification of super-emitter emissions, assessment of their prevalence and relationship to site characteristics, and mitigation with continuous leak detection systems. Chapter 1 summarizes the state of the knowledge of O&G methane emissions. Chapter 2 constructs a spatially-resolved emission inventory to estimate total and O&G methane emissions in the Barnett Shale as part of a coordinated research campaign using multiple top-down and bottom-up methods to quantify emissions. The emission inventory accounts for super-emitters with two-phase Monte Carlo simulations that combine site measurements collected with two approaches: unbiased sampling and targeted sampling of super-emitters. More comprehensive activity data and the inclusion of super-emitters, which account for 19% of O&G emissions, produces a emission inventory that is not statistically different than top-down regional emission estimates. Chapter 3 describes a helicopter-based survey of over 8,000 well pads in seven basins with infrared optical gas imaging to assess high emission sources. Four percent of sites are observed to have high emissions with over 90% of observed sources from tanks. The occurrence of high emissions is weakly correlated to site parameters and the best statistical model explains only 14% of variance, which demonstrates that the occurrence of super-emitters is primarily stochastic. Chapter 4 presents a Gaussian dispersion model for optimizing the placement of continuous leak detection systems at three example well pads. The model demonstrates that large leaks can be detected quickly with first generation systems. Continuous leak detection can be used in the near future to cost-effectively mitigate methane emissions from O&G super-emitters.

  6. Improving the Sensitivity of Mass Spectrometry by Using a New Sheath Flow Electrospray Emitter Array at Subambient Pressures

    DOE PAGES

    Cox, Jonathan T.; Marginean, Ioan; Kelly, Ryan T.; ...

    2014-03-28

    Arrays of chemically etched emitters with individualized sheath gas capillaries have been developed to enhance electrospray ionization (ESI) at subambient pressures. By including an emitter array in a subambient pressure ionization with nanoelectrospray (SPIN) source, ionization and transmission efficiency can be maximized allowing for increased sensitivity in mass spectrometric analyses. The SPIN source eliminates the major ion losses at conventional ESI-mass spectrometry (MS) interface by placing the emitter in the first vacuum region of the instrument. To facilitate stable electrospray currents in such conditions we have developed an improved emitter array with individualized sheath gas around each emitter. The utilitymore » of the new emitter arrays for generating stable multi-electrosprays at subambient pressures was probed by coupling the emitter array/SPIN source with a time of flight (TOF) mass spectrometer. The instrument sensitivity was compared between single emitter/SPIN-MS and multi-emitter/SPIN-MS configurations using an equimolar solution of 9 peptides. An increase in sensitivity correlative to the number of emitters in the array was observed.« less

  7. Rare earth garnet selective emitter

    NASA Technical Reports Server (NTRS)

    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) approximately equal to 0.74, ((4)l(sub 15/2)) - ( (4)l(sub13/2)), for Er-YAG and epsilon(sub lambda) approximately equal to 0.65, ((5)l(sub 7))-((5)l(sub 8)) for Ho-YAG) at excellent candidates for high efficiency selective emitters in the thermophotovoltaics (TPV) systems operating at moderate temperatures (1200-1500K). 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. This paper presents normal spectral emittance, epsilon(sub lambda), measurements of holmium (Ho), and erbium (Er) doped YAG thin film selective emitters at 1500 K, and compares those results with the theoretical spectral emittance.

  8. Improving the Sensitivity of Mass Spectrometry by Using a New Sheath Flow Electrospray Emitter Array at Subambient Pressures

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cox, Jonathan T.; Marginean, Ioan; Kelly, Ryan T.

    Arrays of chemically etched emitters with individualized sheath gas capillaries have been developed to enhance electrospray ionization (ESI) at subambient pressures. By including an emitter array in a subambient pressure ionization with nanoelectrospray (SPIN) source, ionization and transmission efficiency can be maximized allowing for increased sensitivity in mass spectrometric analyses. The SPIN source eliminates the major ion losses at conventional ESI-mass spectrometry (MS) interface by placing the emitter in the first vacuum region of the instrument. To facilitate stable electrospray currents in such conditions we have developed an improved emitter array with individualized sheath gas around each emitter. The utilitymore » of the new emitter arrays for generating stable multi-electrosprays at subambient pressures was probed by coupling the emitter array/SPIN source with a time of flight (TOF) mass spectrometer. The instrument sensitivity was compared between single emitter/SPIN-MS and multi-emitter/SPIN-MS configurations using an equimolar solution of 9 peptides. An increase in sensitivity correlative to the number of emitters in the array was observed.« less

  9. Magnetic field of longitudinal gradient bend

    NASA Astrophysics Data System (ADS)

    Aiba, Masamitsu; Böge, Michael; Ehrlichman, Michael; Streun, Andreas

    2018-06-01

    The longitudinal gradient bend is an effective method for reducing the natural emittance in light sources. It is, however, not a common element. We have analyzed its magnetic field and derived a set of formulae. Based on the derivation, we discuss how to model the longitudinal gradient bend in accelerator codes that are used for designing electron storage rings. Strengths of multipole components can also be evaluated from the formulae, and we investigate the impact of higher order multipole components in a very low emittance lattice.

  10. Direct experimental observation of nonclassicality in ensembles of single-photon emitters

    NASA Astrophysics Data System (ADS)

    Moreva, E.; Traina, P.; Forneris, J.; Degiovanni, I. P.; Ditalia Tchernij, S.; Picollo, F.; Brida, G.; Olivero, P.; Genovese, M.

    2017-11-01

    In this work we experimentally demonstrate a recently proposed criterion addressed to detect nonclassical behavior in the fluorescence emission of ensembles of single-photon emitters. In particular, we apply the method to study clusters of nitrogen-vacancy centers in diamond characterized with single-photon-sensitive confocal microscopy. Theoretical considerations on the behavior of the parameter at any arbitrary order in the presence of Poissonian noise are presented and, finally, the opportunity of detecting manifold coincidences is discussed.

  11. Double opposite-end tubesheet design for a thermovoltaic energy converter

    DOEpatents

    Ashcroft, John M.; Campbell, Brian C.; Depoy, David M.

    2000-01-01

    A method and apparatus for the direct conversion of energy by thermovoltaic energy conversion having first and second tubesheets, at least one photon emitter plate secured to and extending from the first tubesheet, at least one cold plate secured to and extending from the second tubesheet, a plurality of thermovoltaic cells disposed along oppositely disposed exterior surfaces of the cold plate, and means cooperating with the tubesheet for maintaining a vacuum between the photon emitter plate and the cold plate.

  12. Determination of the efficiency of commercially available dose calibrators for beta-emitters.

    PubMed

    Valley, Jean-François; Bulling, Shelley; Leresche, Michel; Wastiel, Claude

    2003-03-01

    The goals of this investigation are to determine whether commercially available dose calibrators can be used to measure the activity of beta-emitting radionuclides used in pain palliation and to establish whether manufacturer-supplied calibration factors are appropriate for this purpose. Six types of commercially available dose calibrators were studied. Dose calibrator response was controlled for 5 gamma-emitters used for calibration or typically encountered in routine use. For the 4 most commonly used beta-emitters ((32)P, (90)Sr, (90)Y, and (169)Er) dose calibrator efficiency was determined in the syringe geometry used for clinical applications. Efficiency of the calibrators was also measured for (153)Sm and (186)Re, 2 beta-emitters with significant gamma-contributions. Source activities were traceable to national standards. All calibrators measured gamma-emitters with a precision of +/-10%, in compliance with Swiss regulatory requirements. For beta-emitters, dose calibrator intrinsic efficiency depends strongly on the maximal energy of the beta-spectrum and is notably low for (169)Er. Manufacturer-supplied calibration factors give accurate results for beta-emitters with maximal beta-energy in the middle-energy range (1 MeV) but are not appropriate for use with low-energy ((169)Er) or high-energy ((90)Y) beta-emitters. beta-emitters with significant gamma-contributions behave like gamma-emitters. Commercially available dose calibrators have an intrinsic efficiency that is sufficient for the measurement of beta-emitters, including beta-emitters with a low maximum beta-energy. Manufacturer-supplied calibration factors are reliable for gamma-emitters and beta-emitters in the middle-energy range. For low- and high-energy beta-emitters, the use of manufacturer-supplied calibration factors introduces significant measurement inaccuracy.

  13. Multinozzle emitter arrays for ultrahigh-throughput nanoelectrospray mass spectrometry

    DOE Office of Scientific and Technical Information (OSTI.GOV)

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

    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 siliconmore » chip before the electrospray mass spectrometry analysis.« less

  14. Phosphorescent cyclometalated complexes for efficient blue organic light-emitting diodes

    PubMed Central

    Suzuri, Yoshiyuki; Oshiyama, Tomohiro; Ito, Hiroto; Hiyama, Kunihisa; Kita, Hiroshi

    2014-01-01

    Phosphorescent emitters are extremely important for efficient organic light-emitting diodes (OLEDs), which attract significant attention. Phosphorescent emitters, which have a high phosphorescence quantum yield at room temperature, typically contain a heavy metal such as iridium and have been reported to emit blue, green and red light. In particular, the blue cyclometalated complexes with high efficiency and high stability are being developed. In this review, we focus on blue cyclometalated complexes. Recent progress of computational analysis necessary to design a cyclometalated complex is introduced. The prediction of the radiative transition is indispensable to get an emissive cyclometalated complex. We summarize four methods to control phosphorescence peak of the cyclometalated complex: (i) substituent effect on ligands, (ii) effects of ancillary ligands on heteroleptic complexes, (iii) design of the ligand skeleton, and (iv) selection of the central metal. It is considered that novel ligand skeletons would be important to achieve both a high efficiency and long lifetime in the blue OLEDs. Moreover, the combination of an emitter and a host is important as well as the emitter itself. According to the dependences on the combination of an emitter and a host, the control of exciton density of the triplet is necessary to achieve both a high efficiency and a long lifetime, because the annihilations of the triplet state cause exciton quenching and material deterioration. PMID:27877712

  15. Phosphorescent cyclometalated complexes for efficient blue organic light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Suzuri, Yoshiyuki; Oshiyama, Tomohiro; Ito, Hiroto; Hiyama, Kunihisa; Kita, Hiroshi

    2014-10-01

    Phosphorescent emitters are extremely important for efficient organic light-emitting diodes (OLEDs), which attract significant attention. Phosphorescent emitters, which have a high phosphorescence quantum yield at room temperature, typically contain a heavy metal such as iridium and have been reported to emit blue, green and red light. In particular, the blue cyclometalated complexes with high efficiency and high stability are being developed. In this review, we focus on blue cyclometalated complexes. Recent progress of computational analysis necessary to design a cyclometalated complex is introduced. The prediction of the radiative transition is indispensable to get an emissive cyclometalated complex. We summarize four methods to control phosphorescence peak of the cyclometalated complex: (i) substituent effect on ligands, (ii) effects of ancillary ligands on heteroleptic complexes, (iii) design of the ligand skeleton, and (iv) selection of the central metal. It is considered that novel ligand skeletons would be important to achieve both a high efficiency and long lifetime in the blue OLEDs. Moreover, the combination of an emitter and a host is important as well as the emitter itself. According to the dependences on the combination of an emitter and a host, the control of exciton density of the triplet is necessary to achieve both a high efficiency and a long lifetime, because the annihilations of the triplet state cause exciton quenching and material deterioration.

  16. Deterministic control of the emission from light sources in 1D nanoporous photonic crystals (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Galisteo-López, Juan F.

    2017-02-01

    Controlling the emission of a light source demands acting on its local photonic environment via the local density of states (LDOS). Approaches to exert such control on large scale samples, commonly relying on self-assembly methods, usually lack from a precise positioning of the emitter within the material. Alternatively expensive and time consuming techniques can be used to produce samples of small dimensions where a deterministic control on emitter position can be achieved. In this work we present a full solution process approach to fabricate photonic architectures containing nano-emitters which position can be controlled with nanometer precision over squared milimiter regions. By a combination of spin and dip coating we fabricate one-dimensional (1D) nanoporous photonic crystals, which potential in different fields such as photovoltaics or sensing has been previously reported, containing monolayers of luminescent polymeric nanospheres. We demonstrate how, by modifying the position of the emitters within the photonic crystal, their emission properties (photoluminescence intensity and angular distribution) can be deterministically modified. Further, the nano-emitters can be used as a probe to study the LDOS distribution within these systems with a spatial resolution of 25 nm (provided by the probe size) carrying out macroscopic measurements over squared milimiter regions. Routes to enhance light-matter interaction in this kind of systems by combining them with metallic surfaces are finally discussed.

  17. Parallel nanomanufacturing via electrohydrodynamic jetting from microfabricated externally-fed emitter arrays

    NASA Astrophysics Data System (ADS)

    Ponce de Leon, Philip J.; Hill, Frances A.; Heubel, Eric V.; Velásquez-García, Luis F.

    2015-06-01

    We report the design, fabrication, and characterization of planar arrays of externally-fed silicon electrospinning emitters for high-throughput generation of polymer nanofibers. Arrays with as many as 225 emitters and with emitter density as large as 100 emitters cm-2 were characterized using a solution of dissolved PEO in water and ethanol. Devices with emitter density as high as 25 emitters cm-2 deposit uniform imprints comprising fibers with diameters on the order of a few hundred nanometers. Mass flux rates as high as 417 g hr-1 m-2 were measured, i.e., four times the reported production rate of the leading commercial free-surface electrospinning sources. Throughput increases with increasing array size at constant emitter density, suggesting the design can be scaled up with no loss of productivity. Devices with emitter density equal to 100 emitters cm-2 fail to generate fibers but uniformly generate electrosprayed droplets. For the arrays tested, the largest measured mass flux resulted from arrays with larger emitter separation operating at larger bias voltages, indicating the strong influence of electrical field enhancement on the performance of the devices. Incorporation of a ground electrode surrounding the array tips helps equalize the emitter field enhancement across the array as well as control the spread of the imprints over larger distances.

  18. Multi-ball and one-ball geolocation

    NASA Astrophysics Data System (ADS)

    Nelson, D. J.; Townsend, J. L.

    2017-05-01

    We present analysis methods that may be used to geolocate emitters using one or more moving receivers. While some of the methods we present may apply to a broader class of signals, our primary interest is locating and tracking ships from short pulsed transmissions, such as the maritime Automatic Identification System (AIS.) The AIS signal is difficult to process and track since the pulse duration is only 25 milliseconds, and the pulses may only be transmitted every six to ten seconds. In this article, we address several problems including accurate TDOA and FDOA estimation methods that do not require searching a two dimensional surface such as the cross-ambiguity surface. As an example, we apply these methods to identify and process AIS pulses from a single emitter, making it possible to geolocate the AIS signal using a single moving receiver.

  19. Turbocharged molecular discovery of OLED emitters: from high-throughput quantum simulation to highly efficient TADF devices

    NASA Astrophysics Data System (ADS)

    Gómez-Bombarelli, Rafael; Aguilera-Iparraguirre, Jorge; Hirzel, Timothy D.; Ha, Dong-Gwang; Einzinger, Markus; Wu, Tony; Baldo, Marc A.; Aspuru-Guzik, Alán.

    2016-09-01

    Discovering new OLED emitters requires many experiments to synthesize candidates and test performance in devices. Large scale computer simulation can greatly speed this search process but the problem remains challenging enough that brute force application of massive computing power is not enough to successfully identify novel structures. We report a successful High Throughput Virtual Screening study that leveraged a range of methods to optimize the search process. The generation of candidate structures was constrained to contain combinatorial explosion. Simulations were tuned to the specific problem and calibrated with experimental results. Experimentalists and theorists actively collaborated such that experimental feedback was regularly utilized to update and shape the computational search. Supervised machine learning methods prioritized candidate structures prior to quantum chemistry simulation to prevent wasting compute on likely poor performers. With this combination of techniques, each multiplying the strength of the search, this effort managed to navigate an area of molecular space and identify hundreds of promising OLED candidate structures. An experimentally validated selection of this set shows emitters with external quantum efficiencies as high as 22%.

  20. Design and optimization of an energy degrader with a multi-wedge scheme based on Geant4

    NASA Astrophysics Data System (ADS)

    Liang, Zhikai; Liu, Kaifeng; Qin, Bin; Chen, Wei; Liu, Xu; Li, Dong; Xiong, Yongqian

    2018-05-01

    A proton therapy facility based on an isochronous superconducting cyclotron is under construction in Huazhong University of Science and Technology (HUST). To meet the clinical requirements, an energy degrader is essential in the beamline to modulate the fixed beam energy extracted from the cyclotron. Because of the multiple Coulomb scattering in the degrader, the beam emittance and the energy spread will be considerably increased during the energy degradation process. Therefore, a set of collimators is designed to restrict the increase in beam emittance after the energy degradation. The energy spread will be reduced in the following beam line which is not discussed in this paper. In this paper, the design considerations of an energy degrader and collimators are introduced, and the properties of the degrader material, degrader structure and the initial beam parameters are discussed using the Geant4 Monte-Carlo toolkit, with the main purpose of improving the overall performance of the degrader by multiple parameter optimization.

  1. Physics issues in diffraction limited storage ring design

    NASA Astrophysics Data System (ADS)

    Fan, Wei; Bai, ZhengHe; Gao, WeiWei; Feng, GuangYao; Li, WeiMin; Wang, Lin; He, DuoHui

    2012-05-01

    Diffraction limited electron storage ring is considered a promising candidate for future light sources, whose main characteristics are higher brilliance, better transverse coherence and better stability. The challenge of diffraction limited storage ring design is how to achieve the ultra low beam emittance with acceptable nonlinear performance. Effective linear and nonlinear parameter optimization methods based on Artificial Intelligence were developed for the storage ring physical design. As an example of application, partial physical design of HALS (Hefei Advanced Light Source), which is a diffraction limited VUV and soft X-ray light source, was introduced. Severe emittance growth due to the Intra Beam Scattering effect, which is the main obstacle to achieve ultra low emittance, was estimated quantitatively and possible cures were discussed. It is inspiring that better performance of diffraction limited storage ring can be achieved in principle with careful parameter optimization.

  2. Emittance preservation during bunch compression with a magnetized beam

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Stratakis, Diktys

    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 tomore » 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.« less

  3. [Evaluation of therapies in oncology by positron emission tomography: towards therapeutical personalization].

    PubMed

    Bonardel, G; Vedrine, L; Aupee, O; Gontier, E; Le Garlantezec, P; Soret, M; Foehrenbach, H

    2009-02-01

    Recently introduced into clinical practice, positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) has proven its utility for diagnosis and staging of malignant diseases on account of its ability for tissue identification. Its utilization is now moving toward the evaluation of anti-tumoral effects of anticancer therapy, because of the correlation between the uptake of a metabolic tracer and malignant cells viability. Metabolic effects of chemotherapy are first observed in cells and this is the explanation for the precocity of scintigraphic visualisation of therapeutic activity. However, monitoring response with FDG-PET requires rigorous method and needs to take into account the limitations of SUV. Moreover, in order to go beyond the limitations of FDG, new tracers are developed and their main indication could be precisely the monitoring of therapy response. The properties of positron emitters allow us to foresee the labelling of the therapeutic molecules themselves in order to try them in vivo before their utilization for a given patient. These prospects are the ground for real treatment personalization in oncology. They open up a wide field of clinical research but the means for image acquisition and radioactive tracers production will be mandatory for anyone who wants to contribute to this work. Due to the current performances of the imaging systems, the critical point will be availability of equipment allowing the designing and synthesis of the radiopharmaceuticals of the future.

  4. A new method for depth profiling reconstruction in confocal microscopy

    NASA Astrophysics Data System (ADS)

    Esposito, Rosario; Scherillo, Giuseppe; Mensitieri, Giuseppe

    2018-05-01

    Confocal microscopy is commonly used to reconstruct depth profiles of chemical species in multicomponent systems and to image nuclear and cellular details in human tissues via image intensity measurements of optical sections. However, the performance of this technique is reduced by inherent effects related to wave diffraction phenomena, refractive index mismatch and finite beam spot size. All these effects distort the optical wave and cause an image to be captured of a small volume around the desired illuminated focal point within the specimen rather than an image of the focal point itself. The size of this small volume increases with depth, thus causing a further loss of resolution and distortion of the profile. Recently, we proposed a theoretical model that accounts for the above wave distortion and allows for a correct reconstruction of the depth profiles for homogeneous samples. In this paper, this theoretical approach has been adapted for describing the profiles measured from non-homogeneous distributions of emitters inside the investigated samples. The intensity image is built by summing the intensities collected from each of the emitters planes belonging to the illuminated volume, weighed by the emitters concentration. The true distribution of the emitters concentration is recovered by a new approach that implements this theoretical model in a numerical algorithm based on the Maximum Entropy Method. Comparisons with experimental data and numerical simulations show that this new approach is able to recover the real unknown concentration distribution from experimental profiles with an accuracy better than 3%.

  5. Quantitative single-particle digital autoradiography with α-particle emitters for targeted radionuclide therapy using the iQID camera

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Miller, Brian W., E-mail: brian.miller@pnnl.gov; Frost, Sofia H. L.; Frayo, Shani L.

    2015-07-15

    Purpose: Alpha-emitting radionuclides exhibit a potential advantage for cancer treatments because they release large amounts of ionizing energy over a few cell diameters (50–80 μm), causing localized, irreparable double-strand DNA breaks that lead to cell death. Radioimmunotherapy (RIT) approaches using monoclonal antibodies labeled with α emitters may thus inactivate targeted cells with minimal radiation damage to surrounding tissues. Tools are needed to visualize and quantify the radioactivity distribution and absorbed doses to targeted and nontargeted cells for accurate dosimetry of all treatment regimens utilizing α particles, including RIT and others (e.g., Ra-223), especially for organs and tumors with heterogeneous radionuclidemore » distributions. The aim of this study was to evaluate and characterize a novel single-particle digital autoradiography imager, the ionizing-radiation quantum imaging detector (iQID) camera, for use in α-RIT experiments. Methods: The iQID camera is a scintillator-based radiation detection system that images and identifies charged-particle and gamma-ray/x-ray emissions spatially and temporally on an event-by-event basis. It employs CCD-CMOS cameras and high-performance computing hardware for real-time imaging and activity quantification of tissue sections, approaching cellular resolutions. In this work, the authors evaluated its characteristics for α-particle imaging, including measurements of intrinsic detector spatial resolutions and background count rates at various detector configurations and quantification of activity distributions. The technique was assessed for quantitative imaging of astatine-211 ({sup 211}At) activity distributions in cryosections of murine and canine tissue samples. Results: The highest spatial resolution was measured at ∼20 μm full width at half maximum and the α-particle background was measured at a rate as low as (2.6 ± 0.5) × 10{sup −4} cpm/cm{sup 2} (40 mm diameter detector area). Simultaneous imaging of multiple tissue sections was performed using a large-area iQID configuration (ø 11.5 cm). Estimation of the {sup 211}At activity distribution was demonstrated at mBq/μg-levels. Conclusions: Single-particle digital autoradiography of α emitters has advantages over traditional film-based autoradiographic techniques that use phosphor screens, in terms of spatial resolution, sensitivity, and activity quantification capability. The system features and characterization results presented in this study show that the iQID is a promising technology for microdosimetry, because it provides necessary information for interpreting alpha-RIT outcomes and for predicting the therapeutic efficacy of cell-targeted approaches using α emitters.« less

  6. Spatial resolution properties of digital autoradiography systems for pre-clinical alpha particle imaging (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Tanguay, Jesse; Benard, Francois; Celler, Anna; Ruth, Thomas; Schaffer, Paul

    2017-03-01

    Attaching alpha-emitting radionuclides to cancer-targeting agents increases the anti-tumor effects of targeted cancer therapies. The success of alpha therapy for treating bone metastases has increased interest in using targeted alpha therapy (TAT) to treat a broad spectrum of metastatic cancers. Estimating radiation doses to targeted tumors, including small (<250 μm) clusters of cancer cells, and to non-targeted tissues is critical in the pre-clinical development of TATs. However, accurate quantification of heterogeneous distributions of alpha-emitters in small metastases is not possible with existing pre-clinical in-vivo imaging systems. Ex-vivo digital autoradiography using a scintillator in combination with an image intensifier and a charged coupled device (CCD) has gained interest for pre-clinical ex-vivo alpha particle imaging. We present a simulation-based analysis of the fundamental spatial resolution limits of digital autoradiography systems. Spatial resolution was quantified in terms of the modulation transfer function (MTF) and Wagner's equivalent aperture. We modeled systems operating in either particle-counting (PC) or energy-integrating (EI) mode using a cascaded systems approach that accounts for: 1) the stopping power of alpha particles; 2) the distance alpha particles travel within the scintillator; 3) optical blur, and; 4) binning in detector elements. We applied our analysis to imaging of astatine-211 using an LYSO scintillator with thickness ranging from 10 μm to 20 μm. Our analysis demonstrates that when these systems are operated in particle-counting mode with a centroid-calculation algorithm, the effective apertures of 35 μm can be achieved, which suggests that digital autoradiography may enable quantifying the uptake of alpha emitters in tumors consisting of a few cancer cells. Future work will investigate the image noise and energy-resolution properties of digital autoradiography systems.

  7. Thermionic converter

    DOEpatents

    Rasor, Ned S.; Britt, Edward J.

    1976-01-01

    A gas-filled thermionic converter is provided with a collector and an emitter having a main emitter region and an auxiliary emitter region in electrical contact with the main emitter region. The main emitter region is so positioned with respect to the collector that a main gap is formed therebetween and the auxiliary emitter region is so positioned with respect to the collector that an auxiliary gap is formed therebetween partially separated from the main gap with access allowed between the gaps to allow ionizable gas in each gap to migrate therebetween. With heat applied to the emitter the work function of the auxiliary emitter region is sufficiently greater than the work function of the collector so that an ignited discharge occurs in the auxiliary gap and the work function of the main emitter region is so related to the work function of the collector that an unignited discharge occurs in the main gap sustained by the ions generated in the auxiliary gap. A current flows through a load coupled across the emitter and collector due to the unignited discharge in the main gap.

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

    NASA Astrophysics Data System (ADS)

    Tang, Wilkin W.; Shiffler, Donald A.; Harris, John R.; Jensen, Kevin L.; Golby, Ken; LaCour, Matthew; Knowles, Tim

    2016-09-01

    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.

  9. Electrochemical formation of field emitters

    DOEpatents

    Bernhardt, Anthony F.

    1999-01-01

    Electrochemical formation of field emitters, particularly useful in the fabrication of flat panel displays. The fabrication involves field emitting points in a gated field emitter structure. Metal field emitters are formed by electroplating and the shape of the formed emitter is controlled by the potential imposed on the gate as well as on a separate counter electrode. This allows sharp emitters to be formed in a more inexpensive and manufacturable process than vacuum deposition processes used at present. The fabrication process involves etching of the gate metal and the dielectric layer down to the resistor layer, and then electroplating the etched area and forming an electroplated emitter point in the etched area.

  10. Ultra-high Temperature Emittance Measurements for Space and Missile Applications

    NASA Technical Reports Server (NTRS)

    Rogers, Jan; Crandall, David

    2009-01-01

    Advanced modeling and design efforts for many aerospace components require high temperature emittance data. Applications requiring emittance data include propulsion systems, radiators, aeroshells, heatshields/thermal protection systems, and leading edge surfaces. The objective of this work is to provide emittance data at ultra-high temperatures. MSFC has a new instrument for the measurement of emittance at ultra-high temperatures, the Ultra-High Temperature Emissometer System (Ultra-HITEMS). AZ Technology Inc. developed the instrument, designed to provide emittance measurements over the temperature range 700-3500K. The Ultra-HITEMS instrument measures the emittance of samples, heated by lasers, in vacuum, using a blackbody source and a Fourier Transform Spectrometer. Detectors in a Nicolet 6700 FT-IR spectrometer measure emittance over the spectral range of 0.4-25 microns. Emitted energy from the specimen and output from a Mikron M390S blackbody source at the same temperature with matched collection geometry are measured. Integrating emittance over the spectral range yields the total emittance. The ratio provides a direct measure of total hemispherical emittance. Samples are heated using lasers. Optical pyrometry provides temperature data. Optical filters prevent interference from the heating lasers. Data for Inconel 718 show excellent agreement with results from literature and ASTM 835. Measurements taken from levitated spherical specimens provide total hemispherical emittance data; measurements taken from flat specimens mounted in the chamber provide near-normal emittance data. Data from selected characterization studies will be presented. The Ultra-HITEMS technique could advance space and missile technologies by advancing the knowledge base and the technology readiness level for ultra-high temperature materials.

  11. Emittance Theory for Thin Film Selective Emitter

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    Thin films of high temperature garnet materials such as yttrium aluminum garnet (YAG) doped with rare earths are currently being investigated as selective emitters. This paper presents a radiative transfer analysis of the thin film emitter. From this analysis the emitter efficiency and power density are calculated. Results based on measured extinction coefficients for erbium-YAG and holmium-YAG are presented. These results indicated that emitter efficiencies of 50 percent and power densities of several watts/sq cm are attainable at moderate temperatures (less than 1750 K).

  12. Rational evaluation of the therapeutic effect and dosimetry of auger electrons for radionuclide therapy in a cell culture model.

    PubMed

    Shinohara, Ayaka; Hanaoka, Hirofumi; Sakashita, Tetsuya; Sato, Tatsuhiko; Yamaguchi, Aiko; Ishioka, Noriko S; Tsushima, Yoshito

    2018-02-01

    Radionuclide therapy with low-energy auger electron emitters may provide high antitumor efficacy while keeping the toxicity to normal organs low. Here we evaluated the usefulness of an auger electron emitter and compared it with that of a beta emitter for tumor treatment in in vitro models and conducted a dosimetry simulation using radioiodine-labeled metaiodobenzylguanidine (MIBG) as a model compound. We evaluated the cellular uptake of 125 I-MIBG and the therapeutic effects of 125 I- and 131 I-MIBG in 2D and 3D PC-12 cell culture models. We used a Monte Carlo simulation code (PHITS) to calculate the absorbed radiation dose of 125 I or 131 I in computer simulation models for 2D and 3D cell cultures. In the dosimetry calculation for the 3D model, several distribution patterns of radionuclide were applied. A higher cumulative dose was observed in the 3D model due to the prolonged retention of MIBG compared to the 2D model. However, 125 I-MIBG showed a greater therapeutic effect in the 2D model compared to the 3D model (respective EC 50 values in the 2D and 3D models: 86.9 and 303.9 MBq/cell), whereas 131 I-MIBG showed the opposite result (respective EC 50 values in the 2D and 3D models: 49.4 and 30.2 MBq/cell). The therapeutic effect of 125 I-MIBG was lower than that of 131 I-MIBG in both models, but the radionuclide-derived difference was smaller in the 2D model. The dosimetry simulation with PHITS revealed the influence of the radiation quality, the crossfire effect, radionuclide distribution, and tumor shape on the absorbed dose. Application of the heterogeneous distribution series dramatically changed the radiation dose distribution of 125 I-MIBG, and mitigated the difference between the estimated and measured therapeutic effects of 125 I-MIBG. The therapeutic effect of 125 I-MIBG was comparable to that of 131 I-MIBG in the 2D model, but the efficacy was inferior to that of 131 I-MIBG in the 3D model, since the crossfire effect is negligible and the homogeneous distribution of radionuclides was insufficient. Thus, auger electrons would be suitable for treating small-sized tumors. The design of radiopharmaceuticals with auger electron emitters requires particularly careful consideration of achieving a homogeneous distribution of the compound in the tumor.

  13. Evidence of low injection efficiency for implanted p-emitters in bipolar 4H-SiC high-voltage diodes

    NASA Astrophysics Data System (ADS)

    Matthus, Christian D.; Huerner, Andreas; Erlbacher, Tobias; Bauer, Anton J.; Frey, Lothar

    2018-06-01

    In this study, the influence of the emitter efficiency on the forward current-voltage characteristics, especially the conductivity modulation of bipolar SiC-diodes was analyzed. It was determined that the emitter efficiency of p-emitters formed by ion implantation is significantly lower compared to p-emitters formed by epitaxy. In contrast to comparable studies, experimental approach was arranged that the influence of the quality of the drift-layer or the thickness of the emitter on the conductivity modulation could be excluded for the fabricated bipolar SiC-diodes of this work. Thus, it can be established that the lower emitter injection efficiency is mainly caused by the reduced electron lifetime in p-emitters formed by ion implantation. Therefore, a significant enhancement of the electron lifetime in implanted p-emitters is mandatory for e.g. SiC-MPS-diodes where the functionality of the devices depends significantly on the injection efficiency.

  14. Measurement of transverse emittance and coherence of double-gate field emitter array cathodes

    PubMed Central

    Tsujino, Soichiro; Das Kanungo, Prat; Monshipouri, Mahta; Lee, Chiwon; Miller, R.J. Dwayne

    2016-01-01

    Achieving small transverse beam emittance is important for high brightness cathodes for free electron lasers and electron diffraction and imaging experiments. Double-gate field emitter arrays with on-chip focussing electrode, operating with electrical switching or near infrared laser excitation, have been studied as cathodes that are competitive with photocathodes excited by ultraviolet lasers, but the experimental demonstration of the low emittance has been elusive. Here we demonstrate this for a field emitter array with an optimized double-gate structure by directly measuring the beam characteristics. Further we show the successful application of the double-gate field emitter array to observe the low-energy electron beam diffraction from suspended graphene in minimal setup. The observed low emittance and long coherence length are in good agreement with theory. These results demonstrate that our all-metal double-gate field emitters are highly promising for applications that demand extremely low-electron bunch-phase space volume and large transverse coherence. PMID:28008918

  15. Measurement of transverse emittance and coherence of double-gate field emitter array cathodes

    NASA Astrophysics Data System (ADS)

    Tsujino, Soichiro; Das Kanungo, Prat; Monshipouri, Mahta; Lee, Chiwon; Miller, R. J. Dwayne

    2016-12-01

    Achieving small transverse beam emittance is important for high brightness cathodes for free electron lasers and electron diffraction and imaging experiments. Double-gate field emitter arrays with on-chip focussing electrode, operating with electrical switching or near infrared laser excitation, have been studied as cathodes that are competitive with photocathodes excited by ultraviolet lasers, but the experimental demonstration of the low emittance has been elusive. Here we demonstrate this for a field emitter array with an optimized double-gate structure by directly measuring the beam characteristics. Further we show the successful application of the double-gate field emitter array to observe the low-energy electron beam diffraction from suspended graphene in minimal setup. The observed low emittance and long coherence length are in good agreement with theory. These results demonstrate that our all-metal double-gate field emitters are highly promising for applications that demand extremely low-electron bunch-phase space volume and large transverse coherence.

  16. Mathematical design of a novel input/instruction device using a moving acoustic emitter

    NASA Astrophysics Data System (ADS)

    Wang, Xianchao; Guo, Yukun; Li, Jingzhi; Liu, Hongyu

    2017-10-01

    This paper is concerned with the mathematical design of a novel input/instruction device using a moving emitter. The emitter acts as a point source and can be installed on a digital pen or worn on the finger of the human being who desires to interact/communicate with the computer. The input/instruction can be recognized by identifying the moving trajectory of the emitter performed by the human being from the collected wave field data. The identification process is modelled as an inverse source problem where one intends to identify the trajectory of a moving point source. There are several salient features of our study which distinguish our result from the existing ones in the literature. First, the point source is moving in an inhomogeneous background medium, which models the human body. Second, the dynamical wave field data are collected in a limited aperture. Third, the reconstruction method is independent of the background medium, and it is totally direct without any matrix inversion. Hence, it is efficient and robust with respect to the measurement noise. Both theoretical justifications and computational experiments are presented to verify our novel findings.

  17. Electrochemical formation of field emitters

    DOEpatents

    Bernhardt, A.F.

    1999-03-16

    Electrochemical formation of field emitters, particularly useful in the fabrication of flat panel displays is disclosed. The fabrication involves field emitting points in a gated field emitter structure. Metal field emitters are formed by electroplating and the shape of the formed emitter is controlled by the potential imposed on the gate as well as on a separate counter electrode. This allows sharp emitters to be formed in a more inexpensive and manufacturable process than vacuum deposition processes used at present. The fabrication process involves etching of the gate metal and the dielectric layer down to the resistor layer, and then electroplating the etched area and forming an electroplated emitter point in the etched area. 12 figs.

  18. Emittance measurements of Space Shuttle orbiter reinforced carbon-carbon

    NASA Technical Reports Server (NTRS)

    Caram, Jose M.; Bouslog, Stanley A.; Cunnington, George R., Jr.

    1992-01-01

    The spectral and total normal emittance of the Reinforced Carbon-Carbon (RCC) used on Space Shuttle nose cap and wing leading edges has been measured at room temperature and at surface temperatures of 1200 to 2100 K. These measurements were made on virgin and two flown RCC samples. Room temperature directional emittance data were also obtained and were used to determine the total hemispherical emittance of RCC as a function of temperature. Results of the total normal emittance for the virgin samples showed good agreement with the current RCC emittance design curve; however, the data from the flown samples showed an increase in the emittance at high temperature possibly due to exposure from flight environments.

  19. Emittance Theory for Cylindrical Fiber Selective Emitter

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.

    1998-01-01

    A fibrous rare earth selective emitter is approximated as an infinitely long cylinder. The spectral emittance, epsilon(lambda), is obtained by solving the radiative transfer equations with appropriate boundary conditions and uniform temperature. For optical depths, Kappa(R) = alpha(lambda)R, where alpha(lambda) is the extinction coefficient and R is the cylinder radius, greater than 1 the spectral emittance is nearly at its maximum value. There is an optimum cylinder radius, R(opt), for maximum emitter efficiency, eta(E). Values for R(opt) are strongly dependent on the number of emission bands of the material. The optimum radius decreases slowly with increasing emitter temperature, while the maximum efficiency and useful radiated power increase rapidly with increasing temperature.

  20. Nanozeolite bioconjugates labeled with 223Ra for targeted alpha therapy.

    PubMed

    Piotrowska, Agata; Męczyńska-Wielgosz, Sylwia; Majkowska-Pilip, Agnieszka; Koźmiński, Przemysław; Wójciuk, Grzegorz; Cędrowska, Edyta; Bruchertseifer, Frank; Morgenstern, Alfred; Kruszewski, Marcin; Bilewicz, Aleksander

    2017-04-01

    Alpha particle emitting isotopes are of considerable interest for radionuclide therapy because of their high cytotoxicity and short path length. Among the many α emitters, 223 Ra exhibits very attractive nuclear properties for application in radionuclide therapy. The decay of this radioisotope and its daughters is accompanied by the emission of four α-particles, releasing 27.9MeV of cumulative energy. Unfortunately the lack of an appropriate bifunctional ligand for radium has so far been a main obstacle for the application of 223 Ra in receptor targeted therapy. In our studies we investigated the use of nanozeolite-Substance P bioconjugates as vehicles for 223 Ra radionuclides for targeted α therapy. The sodium form of an A-type of nanozeolite (NaA) was synthesized using the template method. Next, the nanozeolite particles were conjugated to the Substance P (5-11) peptide fragment, which targets NK-1 receptors on glioma cells. The obtained bioconjugate was characterized by transmission emission spectroscopy, thermogravimetric analysis and dynamic light scattering analysis. The NaA-silane-PEG-SP(5-11) bioconjugates were labeled with 223 Ra by exchange of the Na + cation and the stability, receptor affinity and cytotoxicity of the obtained radiobioconjugates were tested. The 223 Ra-labeled nanozeolite bioconjugate almost quantitatively retains 223 Ra in vitro after 6days, while the retention of decay products varies from 90 to 95%. The synthesized 223 RaA-silane-PEG-SP(5-11) showed high receptor affinity toward NK-1 receptor expressing glioma cells and exhibited a high cytotoxic effect in vitro. Substance P functionalized nanozeolite-A represents a viable solution for the use of the 223 Ra in vivo generator as a therapeutic construct for targeting glioma cells. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Advances in iterative non-uniformity correction techniques for infrared scene projection

    NASA Astrophysics Data System (ADS)

    Danielson, Tom; Franks, Greg; LaVeigne, Joe; Prewarski, Marcus; Nehring, Brian

    2015-05-01

    Santa Barbara Infrared (SBIR) is continually developing improved methods for non-uniformity correction (NUC) of its Infrared Scene Projectors (IRSPs) as part of its comprehensive efforts to achieve the best possible projector performance. The most recent step forward, Advanced Iterative NUC (AI-NUC), improves upon previous NUC approaches in several ways. The key to NUC performance is achieving the most accurate possible input drive-to-radiance output mapping for each emitter pixel. This requires many highly-accurate radiance measurements of emitter output, as well as sophisticated manipulation of the resulting data set. AI-NUC expands the available radiance data set to include all measurements made of emitter output at any point. In addition, it allows the user to efficiently manage that data for use in the construction of a new NUC table that is generated from an improved fit of the emitter response curve. Not only does this improve the overall NUC by offering more statistics for interpolation than previous approaches, it also simplifies the removal of erroneous data from the set so that it does not propagate into the correction tables. AI-NUC is implemented by SBIR's IRWindows4 automated test software as part its advanced turnkey IRSP product (the Calibration Radiometry System or CRS), which incorporates all necessary measurement, calibration and NUC table generation capabilities. By employing AI-NUC on the CRS, SBIR has demonstrated the best uniformity results on resistive emitter arrays to date.

  2. Method of depositing multi-layer carbon-based coatings for field emission

    DOEpatents

    Sullivan, John P.; Friedmann, Thomas A.

    1999-01-01

    A novel field emitter device for cold cathode field emission applications, comprising a multi-layer resistive carbon film. The multi-layered film of the present invention is comprised of at least two layers of a resistive carbon material, preferably amorphous-tetrahedrally coordinated carbon, such that the resistivities of adjacent layers differ. For electron emission from the surface, the preferred structure comprises a top layer having a lower resistivity than the bottom layer. For edge emitting structures, the preferred structure of the film comprises a plurality of carbon layers, wherein adjacent layers have different resistivities. Through selection of deposition conditions, including the energy of the depositing carbon species, the presence or absence of certain elements such as H, N, inert gases or boron, carbon layers having desired resistivities can be produced. Field emitters made according the present invention display improved electron emission characteristics in comparison to conventional field emitter materials.

  3. Method of depositing multi-layer carbon-based coatings for field emission

    DOEpatents

    Sullivan, J.P.; Friedmann, T.A.

    1999-08-10

    A novel field emitter device is disclosed for cold cathode field emission applications, comprising a multi-layer resistive carbon film. The multi-layered film of the present invention is comprised of at least two layers of a resistive carbon material, preferably amorphous-tetrahedrally coordinated carbon, such that the resistivities of adjacent layers differ. For electron emission from the surface, the preferred structure comprises a top layer having a lower resistivity than the bottom layer. For edge emitting structures, the preferred structure of the film comprises a plurality of carbon layers, wherein adjacent layers have different resistivities. Through selection of deposition conditions, including the energy of the depositing carbon species, the presence or absence of certain elements such as H, N, inert gases or boron, carbon layers having desired resistivities can be produced. Field emitters made according the present invention display improved electron emission characteristics in comparison to conventional field emitter materials. 8 figs.

  4. Beam conditioning for FELs: Consequences and methods

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wolski, A.; Penn, G.; Sessler, A.

    2004-06-29

    The consequences of beam conditioning in four example cases (VISA, a Soft X-Ray FEL, LCLS and a ''Greenfield'' FEL) are examined. It is shown that in emittance limited cases, proper conditioning reduces sensitivity to the transverse emittance and, furthermore, allows for stronger focusing in the undulator. Simulations show higher saturation power, with gain lengths reduced by a factor of two or more. The beam dynamics in a general conditioning system are studied, with ''matching conditions'' derived for achieving conditioning without growth in the effective emittance. Various conditioning lattices are considered, and expressions derived for the amount of conditioning provided inmore » each case when the matching conditions are satisfied. These results show that there is no fundamental obstacle to producing beam conditioning, and that the problem can be reduced to one of proper lattice design. Nevertheless, beam conditioning will not be easy to implement in practice.« less

  5. Efficient fabrication of carbon nanotube micro tip arrays by tailoring cross-stacked carbon nanotube sheets.

    PubMed

    Wei, Yang; Liu, Peng; Zhu, Feng; Jiang, Kaili; Li, Qunqing; Fan, Shoushan

    2012-04-11

    Carbon nanotube (CNT) micro tip arrays with hairpin structures on patterned silicon wafers were efficiently fabricated by tailoring the cross-stacked CNT sheet with laser. A blade-like structure was formed at the laser-cut edges of the CNT sheet. CNT field emitters, pulled out from the end of the hairpin by an adhesive tape, can provide 150 μA intrinsic emission currents with low beam noise. The nice field emission is ascribed to the Joule-heating-induced desorption of the emitter surface by the hairpin structure, the high temperature annealing effect, and the surface morphology. The CNT emitters with hairpin structures will greatly promote the applications of CNTs in vacuum electronic devices and hold the promises to be used as the hot tips for thermochemical nanolithography. More CNT-based structures and devices can be fabricated on a large scale by this versatile method. © 2012 American Chemical Society

  6. Radioactive sample effects on EDXRF spectra

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Worley, Christopher G

    2008-01-01

    Energy dispersive X-ray fluorescence (EDXRF) is a rapid, straightforward method to determine sample elemental composition. A spectrum can be collected in a few minutes or less, and elemental content can be determined easily if there is adequate energy resolution. Radioactive alpha emitters, however, emit X-rays during the alpha decay process that complicate spectral interpretation. This is particularly noticeable when using a portable instrument where the detector is located in close proximity to the instrument analysis window held against the sample. A portable EDXRF instrument was used to collect spectra from specimens containing plutonium-239 (a moderate alpha emitter) and americium-241 (amore » heavy alpha emitter). These specimens were then analyzed with a wavelength dispersive XRF (WDXRF) instrument to demonstrate the differences to which sample radiation-induced X-ray emission affects the detectors on these two types of XRF instruments.« less

  7. MONTE CARLO SIMULATION OF THE BREMSSTRAHLUNG RADIATION FOR THE MEASUREMENT OF AN INTERNAL CONTAMINATION WITH PURE-BETA EMITTERS IN VIVO.

    PubMed

    Fantínová, K; Fojtík, P; Malátová, I

    2016-09-01

    Rapid measurement techniques are required for a large-scale emergency monitoring of people. In vivo measurement of the bremsstrahlung radiation produced by incorporated pure-beta emitters can offer a rapid technique for the determination of such radionuclides in the human body. This work presents a method for the calibration of spectrometers, based on the use of UPh-02T (so-called IGOR) phantom and specific (90)Sr/(90)Y sources, which can account for recent as well as previous contaminations. The process of the whole- and partial-body counter calibration in combination with application of a Monte Carlo code offers readily extension also to other pure-beta emitters and various exposure scenarios. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  8. Calculated photonic structures for infrared emittance control

    NASA Astrophysics Data System (ADS)

    Rung, Andreas; Ribbing, Carl G.

    2002-06-01

    Using an available program package based on the transfer-matrix method, we calculated the photonic band structure for two different structures: a quasi-three-dimensional crystal of square air rods in a high-index matrix and an opal structure of high-index spheres in a matrix of low index, epsilon = 1.5. The high index used is representative of gallium arsenide in the thermal infrared range. The geometric parameters of the rod dimension, sphere radius, and lattice constants were chosen to give total reflectance for normal incidence, i.e., minimum thermal emittance, in either one of the two infrared atmospheric windows. For these four photonic crystals, the bulk reflectance spectra and the wavelength-averaged thermal emittance as a function of crystal thickness were calculated. The results reveal that potentially useful thermal signature suppression is obtained for crystals as thin as 20-50 mum, i.e., comparable with that of a paint layer.

  9. Crystalline silicon solar cells with high resistivity emitter

    NASA Astrophysics Data System (ADS)

    Panek, P.; Drabczyk, K.; Zięba, P.

    2009-06-01

    The paper presents a part of research targeted at the modification of crystalline silicon solar cell production using screen-printing technology. The proposed process is based on diffusion from POCl3 resulting in emitter with a sheet resistance on the level of 70 Ω/□ and then, shaped by high temperature passivation treatment. The study was focused on a shallow emitter of high resistivity and on its influence on output electrical parameters of a solar cell. Secondary ion mass spectrometry (SIMS) has been employed for appropriate distinguishing the total donor doped profile. The solar cell parameters were characterized by current-voltage characteristics and spectral response (SR) methods. Some aspects playing a role in suitable manufacturing process were discussed. The situation in a photovoltaic industry with emphasis on silicon supply and current prices of solar cells, modules and photovoltaic (PV) systems are described. The economic and quantitative estimation of the PV world market is shortly discussed.

  10. Thermal emittance from ionization-induced trapping in plasma accelerators

    DOE PAGES

    Schroeder, C.  B.; Vay, J. -L.; Esarey, E.; ...

    2014-10-03

    The minimum obtainable transverse emittance (thermal emittance) of electron beams generated and trapped in plasma-based accelerators using laser ionization injection is examined. The initial transverse phase space distribution following ionization and passage through the laser is derived, and expressions for the normalized transverse beam emittance, both along and orthogonal to the laser polarization, are presented. Results are compared to particle-in-cell simulations. Ultralow emittance beams can be generated using laser ionization injection into plasma accelerators, and examples are presented showing normalized emittances on the order of tens of nm.

  11. High performance incandescent lighting using a selective emitter and nanophotonic filters

    NASA Astrophysics Data System (ADS)

    Leroy, Arny; Bhatia, Bikram; Wilke, Kyle; Ilic, Ognjen; Soljačić, Marin; Wang, Evelyn N.

    2017-09-01

    Previous approaches for improving the efficiency of incandescent light bulbs (ILBs) have relied on tailoring the emitted spectrum using cold-side interference filters that reflect the infrared energy back to the emitter while transmitting the visible light. While this approach has, in theory, potential to surpass light-emitting diodes (LEDs) in terms of luminous efficiency while conserving the excellent color rendering index (CRI) inherent to ILBs, challenges such as low view factor between the emitter and filter, high emitter (>2800 K) and filter temperatures and emitter evaporation have significantly limited the maximum efficiency. In this work, we first analyze the effect of non-idealities in the cold-side filter, the emitter and the view factor on the luminous efficiency. Second, we theoretically and experimentally demonstrate that the loss in efficiency associated with low view factors can be minimized by using a selective emitter (e.g., high emissivity in the visible and low emissivity in the infrared) with a filter. Finally, we discuss the challenges in achieving a high performance and long-lasting incandescent light source including the emitter and filter thermal stability as well as emitter evaporation.

  12. Close proximity electrostatic effect from small clusters of emitters

    NASA Astrophysics Data System (ADS)

    Dall'Agnol, Fernando F.; de Assis, Thiago A.

    2017-10-01

    Using a numerical simulation based on the finite-element technique, this work investigates the field emission properties from clusters of a few emitters at close proximity, by analyzing the properties of the maximum local field enhancement factor (γm ) and the corresponding emission current. At short distances between the emitters, we show the existence of a nonintuitive behavior, which consists of the increasing of γm as the distance c between the emitters decreases. Here we investigate this phenomenon for clusters with 2, 3, 4 and 7 identical emitters and study the influence of the proximity effect in the emission current, considering the role of the aspect ratio of the individual emitters. Importantly, our results show that peripheral emitters with high aspect-ratios in large clusters can, in principle, significantly increase the emitted current as a consequence only of the close proximity electrostatic effect (CPEE). This phenomenon can be seen as a physical mechanism to produce self-oscillations of individual emitters. We discuss new insights for understanding the nature of self-oscillations in emitters based on the CPEE, including applications to nanometric oscillators.

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

    DOEpatents

    Musket, Ronald G.

    1999-11-30

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

  14. Nullspace MUSIC and Improved Radio Frequency Emitter Geolocation from a Mobile Antenna Array

    NASA Astrophysics Data System (ADS)

    Kintz, Andrew L.

    This work advances state-of-the-art Radio Frequency (RF) emitter geolocation from an airborne or spaceborne antenna array. With an antenna array, geolocation is based on Direction of Arrival (DOA) estimation algorithms such as MUSIC. The MUSIC algorithm applies to arbitrary arrays of polarization sensitive antennas and yields high resolution. However, MUSIC fails to obtain its theoretical resolution for simultaneous, closely spaced, co-frequency signals. We propose the novel Nullspace MUSIC algorithm, which outperforms MUSIC and its existing modifications while maintaining MUSIC(apostrophe)s fundamental orthogonality test. Nullspace MUSIC applies a divide-and-conquer approach and estimates a single DOA at a time. Additionally, an antenna array on an aircraft cannot be perfectly calibrated. RF waves are blocked, reflected, and scattered in a time-varying fashion by the platform around the antenna array. Consequently, full-wave electromagnetics simulations or demanding measurements of the entire platform cannot eliminate the mismatch between the true, in-situ antenna patterns and the antenna patterns that are available for DOA estimation (the antenna array manifold). Platform-induced manifold mismatch severely degrades MUSIC(apostrophe)s resolution and accuracy. We show that Nullspace MUSIC improves DOA accuracy for well separated signals that are incident on an airborne antenna array. Conventionally, geolocation from a mobile platform draws Lines of Bearing (LOB) from the antenna array along the DOAs to find the locations where the DOAs intersect with the ground. However, averaging the LOBs in the global coordinate system yields large errors due to geometric dilution of precision. Since averaging positions fails, a single emitter is typically located by finding the position on the ground that yields the Minimum Apparent Angular Error (MAAE) for the DOA estimates over a flight. We extend the MAAE approach to cluster LOBs from multiple emitters. MAAE clustering geolocates multiple simultaneous and co-frequency emitters in spite of highly erratic DOA estimates. We also mitigate manifold mismatch by applying the Direct Mapping Method (DMM). DMM averages DOA spectra on the earth(apostrophe)s surface and estimates the emitter locations directly from the composite spectrum. In the example results presented, our goal is to geolocate four diversely polarized emitters with a seven-element antenna array. This is too challenging for MAAE and DMM. We fuse Nullspace MUSIC and DMM into the novel Nullspace DMM algorithm and demonstrate that Nullspace DMM locates all emitters. Finally, we apply the proposed geolocation algorithms to real-world experimental data. A six-element antenna array and Data Collection System (DCS) were installed on a small aircraft. The DCS recorded signals from four live transmitters during a three-hour flight over Columbus, Ohio. The four emitters were geolocated from various segments of the flight. As expected, individual DOA estimates were erratic and widespread due to the airplane(apostrophe)s perturbations of the measured array manifold. MAAE and DMM locate at most three of the four emitters. On the other hand, Nullspace DMM yields unambiguous estimates for every emitter in every flight segment. The successful experimental trials show that Nullspace DMM could significantly enhance airborne emitter geolocation in missions such as RF spectrum enforcement, locating unknown transmitters for defense, and search and rescue operations.

  15. Experimental Study of Coherent Synchrotron Radiation in the Emittance Exchange Line at the A0-Photoinjector

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

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

  16. Synthesis, photophysical and electrochemical properties of a blue emitter with binaphthalene and carbazole units.

    PubMed

    Guo, Lixia; Wang, Xiaoju; Feng, Liheng

    2018-08-05

    A blue emitter, 3,3'-(2,2'-dimethoxy-[1,1'-binaphthalene]-6,6'-diyl)bis(9-benzyl-9H-carbazole), was synthesized by Suzuki coupling reaction. The photophysical properties of the emitter in solution were firstly investigated by UV-Vis absorption and fluorescence emission techniques. The results indicate that the emitter has excellent optical and electron transfer properties. The maximum absorption and emission peaks of the emitter are 302 nm and 406 nm with 67.4% fluorescence quantum yield in chloroform, respectively. Thermal stability study reveals that the emitter has a good thermal stability (Td > 330 °C, Tg > 160 °C). Electrochemical Redox properties of the emitters were measured by cyclic voltammetry, and the energy gaps of highest occupied molecular orbital and the lowest unoccupied molecular orbital levels are in good agreement with the results of theoretical calculation. Furthermore, the multilayer electrochemcial device with the emitter was fabricated and its properties were explored. The wavelength of electroluminescence for the device with this emitter locates at 428 nm. These results indicate the emitter as a deep blue-emitting material has promising application in organic light-emitting diode devices. Copyright © 2018 Elsevier B.V. All rights reserved.

  17. Amorphous-diamond electron emitter

    DOEpatents

    Falabella, Steven

    2001-01-01

    An electron emitter comprising a textured silicon wafer overcoated with a thin (200 .ANG.) layer of nitrogen-doped, amorphous-diamond (a:D-N), which lowers the field below 20 volts/micrometer have been demonstrated using this emitter compared to uncoated or diamond coated emitters wherein the emission is at fields of nearly 60 volts/micrometer. The silicon/nitrogen-doped, amorphous-diamond (Si/a:D-N) emitter may be produced by overcoating a textured silicon wafer with amorphous-diamond (a:D) in a nitrogen atmosphere using a filtered cathodic-arc system. The enhanced performance of the Si/a:D-N emitter lowers the voltages required to the point where field-emission displays are practical. Thus, this emitter can be used, for example, in flat-panel emission displays (FEDs), and cold-cathode vacuum electronics.

  18. Rare Earth Doped Yttrium Aluminum Garnet (YAG) Selective Emitters

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Pal, AnnaMarie T.; Patton, Martin O.; Jenkins, Phillip P.

    1999-01-01

    As a result of their electron structure, rare earth ions in crystals at high temperature emit radiation in several narrow bands rather than in a continuous blackbody manner. This study presents a spectral emittance model for films and cylinders of rare earth doped yttrium aluminum garnets. Good agreement between experimental and theoretical film spectral emittances was found for erbium and holmium aluminum garnets. Spectral emittances of films are sensitive to temperature differences across the film. For operating conditions of interest, the film emitter experiences a linear temperature variation whereas the cylinder emitter has a more advantageous uniform temperature. Emitter efficiency is also a sensitive function of temperature. For holminum aluminum garnet film the efficiency is 0.35 at 1446K but only 0.27 at 1270 K.

  19. Emittance Theory for Cylindrical Fiber Selective Emitter

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.

    1998-01-01

    A fibrous rare earth selective emitter is approximated as an infinitely long, cylinder. The spectral emittance, e(sub x), is obtained L- by solving the radiative transfer equations with appropriate boundary conditions and uniform temperature. For optical depth, K(sub R), where alpha(sub lambda), is the extinction coefficient and R is the cylinder radius, greater than 1 the spectral emittance depths, K(sub R) alpha(sub lambda)R, is nearly at its maximum value. There is an optimum cylinder radius, R(sub opt) for maximum emitter efficiency, n(sub E). Values for R(sub opt) are strongly dependent on the number of emission bands of the material. The optimum radius decreases slowly with increasing emitter temperature, while the maximum efficiency and useful radiated power increase rapidly with increasing, temperature.

  20. Emittance Measurements Relevant to a 250 W(sub t) Class RTPV Generator for Space Exploration

    NASA Technical Reports Server (NTRS)

    Wolford, Dave; Chubb, Donald; Clark, Eric; Pal, Anna Maria; Scheiman, Dave; Colon, Jack

    2009-01-01

    A proposed 250 Wt Radioisotope Thermophotovoltaic (RTPV) power system for utilization in lunar exploration and the subsequent exploration of Mars is described. Details of emitter selection are outlined for use in a maintenance free power supply that is productive over a 14-year mission life. Thorough knowledge of a material s spectral emittance is essential for accurate modeling of the RTPV system. While sometimes treated as a surface effect, emittance involves radiation from within a material. This creates a complex thermal gradient which is a combination of conductive and radiative heat transfer mechanisms. Emittance data available in the literature is a valuable resource but it is particular to the test sample s physical characteristics and the test environment. Considerations for making spectral emittance measurements relevant to RTPV development are discussed. Measured spectral emittance data of refractory emitter materials is given. Planned measurement system modifications to improve relevance to the current project are presented.

  1. Selective far-field addressing of coupled quantum dots in a plasmonic nanocavity.

    PubMed

    Tang, Jianwei; Xia, Juan; Fang, Maodong; Bao, Fanglin; Cao, Guanjun; Shen, Jianqi; Evans, Julian; He, Sailing

    2018-04-27

    Plasmon-emitter hybrid nanocavity systems exhibit strong plasmon-exciton interactions at the single-emitter level, showing great potential as testbeds and building blocks for quantum optics and informatics. However, reported experiments involve only one addressable emitting site, which limits their relevance for many fundamental questions and devices involving interactions among emitters. Here we open up this critical degree of freedom by demonstrating selective far-field excitation and detection of two coupled quantum dot emitters in a U-shaped gold nanostructure. The gold nanostructure functions as a nanocavity to enhance emitter interactions and a nanoantenna to make the emitters selectively excitable and detectable. When we selectively excite or detect either emitter, we observe photon emission predominantly from the target emitter with up to 132-fold Purcell-enhanced emission rate, indicating individual addressability and strong plasmon-exciton interactions. Our work represents a step towards a broad class of plasmonic devices that will enable faster, more compact optics, communication and computation.

  2. Benchmarking of measurement and simulation of transverse rms-emittance growth

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jeon, Dong-O

    2008-01-01

    Transverse emittance growth along the Alvarez DTL section is a major concern with respect to the preservation of beam quality of high current beams at the GSI UNILAC. In order to define measures to reduce this growth appropriated tools to simulate the beam dynamics are indispensable. This paper is about the benchmarking of three beam dynamics simulation codes, i.e. DYNAMION, PARMILA, and PARTRAN against systematic measurements of beam emittances for different machine settings. Experimental set-ups, data reduction, the preparation of the simulations, and the evaluation of the simulations will be described. It was found that the measured 100%-rmsemittances behind themore » DTL exceed the simulated values. Comparing measured 90%-rms-emittances to the simulated 95%-rms-emittances gives fair to good agreement instead. The sum of horizontal and vertical emittances is even described well by the codes as long as experimental 90%-rmsemittances are compared to simulated 95%-rms-emittances. Finally, the successful reduction of transverse emittance growth by systematic beam matching is reported.« less

  3. An experimental approach to improve the Monte Carlo modelling of offline PET/CT-imaging of positron emitters induced by scanned proton beams

    NASA Astrophysics Data System (ADS)

    Bauer, J.; Unholtz, D.; Kurz, C.; Parodi, K.

    2013-08-01

    We report on the experimental campaign carried out at the Heidelberg Ion-Beam Therapy Center (HIT) to optimize the Monte Carlo (MC) modelling of proton-induced positron-emitter production. The presented experimental strategy constitutes a pragmatic inverse approach to overcome the known uncertainties in the modelling of positron-emitter production due to the lack of reliable cross-section data for the relevant therapeutic energy range. This work is motivated by the clinical implementation of offline PET/CT-based treatment verification at our facility. Here, the irradiation induced tissue activation in the patient is monitored shortly after the treatment delivery by means of a commercial PET/CT scanner and compared to a MC simulated activity expectation, derived under the assumption of a correct treatment delivery. At HIT, the MC particle transport and interaction code FLUKA is used for the simulation of the expected positron-emitter yield. For this particular application, the code is coupled to externally provided cross-section data of several proton-induced reactions. Studying experimentally the positron-emitting radionuclide yield in homogeneous phantoms provides access to the fundamental production channels. Therefore, five different materials have been irradiated by monoenergetic proton pencil beams at various energies and the induced β+ activity subsequently acquired with a commercial full-ring PET/CT scanner. With the analysis of dynamically reconstructed PET images, we are able to determine separately the spatial distribution of different radionuclide concentrations at the starting time of the PET scan. The laterally integrated radionuclide yields in depth are used to tune the input cross-section data such that the impact of both the physical production and the imaging process on the various positron-emitter yields is reproduced. The resulting cross-section data sets allow to model the absolute level of measured β+ activity induced in the investigated targets within a few per cent. Moreover, the simulated distal activity fall-off positions, representing the central quantity for treatment monitoring in terms of beam range verification, are found to agree within 0.6 mm with the measurements at different initial beam energies in both homogeneous and heterogeneous targets. Based on work presented at the Third European Workshop on Monte Carlo Treatment Planning (Seville, 15-18 May 2012).

  4. Emitter utilization in heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Quach, T.; Jenkins, T.; Barrette, J.; Bozada, C.; Cerny, C.; Desalvo, G.; Dettmer, R.; Ebel, J.; Gillespie, J.; Havasy, C.; Ito, C.; Nakano, K.; Pettiford, C.; Sewell, J.; Via, D.; Anholt, R.

    1997-09-01

    We compare measured collector current densities, cutoff frequencies ( ft), and transducer gains for thermally shunted heterojunction bipolar transistors with 2-16 μm emitter dot diameters or 2-8 μm emitter bar widths with models of the emitter utilization factors. Models that do not take emitter resistance into account predict that the d.c. utilization factors are below 0.7 for collector current densities greater than 6 × 10 4 A cm -2 and emitter diameters or widths greater than 8 μm. However, because the current gains are compressed by the emitter resistances at those current densities, the measured utilization factors are close to 1, which agrees with models that include emitter resistance. A.c. utilization factors are evident in the transistor Y parameters. For example, Re|Y 21z.sfnc drops off at high frequencies more steeply in HBTs with large emitter diameters or widths than in small ones. However, measured data shows that the HBT a.c. current gains h21 or ft values are not influenced by the a.c. utilization factor. A.c. utilization effects on HBT performance parameters such as small signal and power gains, output power, and power added efficiency are also examined.

  5. Development of activity pencil beam algorithm using measured distribution data of positron emitter nuclei generated by proton irradiation of targets containing (12)C, (16)O, and (40)Ca nuclei in preparation of clinical application.

    PubMed

    Miyatake, Aya; Nishio, Teiji; Ogino, Takashi

    2011-10-01

    The purpose of this study is to develop a new calculation algorithm that is satisfactory in terms of the requirements for both accuracy and calculation time for a simulation of imaging of the proton-irradiated volume in a patient body in clinical proton therapy. The activity pencil beam algorithm (APB algorithm), which is a new technique to apply the pencil beam algorithm generally used for proton dose calculations in proton therapy to the calculation of activity distributions, was developed as a calculation algorithm of the activity distributions formed by positron emitter nuclei generated from target nuclear fragment reactions. In the APB algorithm, activity distributions are calculated using an activity pencil beam kernel. In addition, the activity pencil beam kernel is constructed using measured activity distributions in the depth direction and calculations in the lateral direction. (12)C, (16)O, and (40)Ca nuclei were determined as the major target nuclei that constitute a human body that are of relevance for calculation of activity distributions. In this study, "virtual positron emitter nuclei" was defined as the integral yield of various positron emitter nuclei generated from each target nucleus by target nuclear fragment reactions with irradiated proton beam. Compounds, namely, polyethylene, water (including some gelatin) and calcium oxide, which contain plenty of the target nuclei, were irradiated using a proton beam. In addition, depth activity distributions of virtual positron emitter nuclei generated in each compound from target nuclear fragment reactions were measured using a beam ON-LINE PET system mounted a rotating gantry port (BOLPs-RGp). The measured activity distributions depend on depth or, in other words, energy. The irradiated proton beam energies were 138, 179, and 223 MeV, and measurement time was about 5 h until the measured activity reached the background level. Furthermore, the activity pencil beam data were made using the activity pencil beam kernel, which was composed of the measured depth data and the lateral data including multiple Coulomb scattering approximated by the Gaussian function, and were used for calculating activity distributions. The data of measured depth activity distributions for every target nucleus by proton beam energy were obtained using BOLPs-RGp. The form of the depth activity distribution was verified, and the data were made in consideration of the time-dependent change of the form. Time dependence of an activity distribution form could be represented by two half-lives. Gaussian form of the lateral distribution of the activity pencil beam kernel was decided by the effect of multiple Coulomb scattering. Thus, the data of activity pencil beam involving time dependence could be obtained in this study. The simulation of imaging of the proton-irradiated volume in a patient body using target nuclear fragment reactions was feasible with the developed APB algorithm taking time dependence into account. With the use of the APB algorithm, it was suggested that a system of simulation of activity distributions that has levels of both accuracy and calculation time appropriate for clinical use can be constructed.

  6. Ion Motion Induced Emittance Growth of Matched Electron Beams in Plasma Wakefields.

    PubMed

    An, Weiming; Lu, Wei; Huang, Chengkun; Xu, Xinlu; Hogan, Mark J; Joshi, Chan; Mori, Warren B

    2017-06-16

    Plasma-based acceleration is being considered as the basis for building a future linear collider. Nonlinear plasma wakefields have ideal properties for accelerating and focusing electron beams. Preservation of the emittance of nano-Coulomb beams with nanometer scale matched spot sizes in these wakefields remains a critical issue due to ion motion caused by their large space charge forces. We use fully resolved quasistatic particle-in-cell simulations of electron beams in hydrogen and lithium plasmas, including when the accelerated beam has different emittances in the two transverse planes. The projected emittance initially grows and rapidly saturates with a maximum emittance growth of less than 80% in hydrogen and 20% in lithium. The use of overfocused beams is found to dramatically reduce the emittance growth. The underlying physics that leads to the lower than expected emittance growth is elucidated.

  7. Prototype of a subsurface drip irrigation emitter: Manufacturing, hydraulic evaluation and experimental analyses

    NASA Astrophysics Data System (ADS)

    Souza, Wanderley De Jesus; Rodrigues Sinobas, Leonor; Sánchez, Raúl; Arriel Botrel, Tarlei; Duarte Coelho, Rubens

    2013-04-01

    Root and soil intrusion into the conventional emitters is one of the major disadvantages to obtain a good uniformity of water application in subsurface drip irrigation (SDI). In the last years, there have been different approaches to reduce these problems such as the impregnation of emitters with herbicide, and the search for an emitter geometry impairing the intrusion of small roots. Within the last this study, has developed and evaluated an emitter model which geometry shows specific physical features to prevent emitter clogging. This work was developed at the Biosystems Engineering Department at ESALQ-USP/Brazil, and it is a part of a research in which an innovated emitteŕs model for SDI has been developed to prevent root and soil particles intrusion. An emitter with a mechanical-hydraulic mechanism (opening and closing the water outlet) for SDI was developed and manufactured using a mechanical lathe process. It was composed by a silicon elastic membrane a polyethylene tube and a Vnyl Polychloride membrane protector system. In this study the performance of the developed prototype was assessed in the laboratory and in the field conditions. In the laboratory, uniformity of water application was calculated by the water emission uniformity coefficient (CUE), and the manufacturer's coefficient of variation (CVm). In addition, variation in the membrane diameter submitted to internal pressures; head losses along the membrane, using the energy equation; and, precision and accuracy of the equation model, analyzed by Pearson's correlation coefficient (r), and by Willmott's concordance index (d) were also calculated with samples of the developed emitters. In the field, the emitters were installed in pots with and without sugar cane culture from October 2010 to January 2012. During this time, flow rate in 20 emitters were measured periodically, and the aspects of them about clogging at the end of the experiment. Emitters flow rates were measured quarterly to calculate: relative flow rate (QR); flow disturbance (FD); CUE; and, variation coefficient of relative flow (CVQR). In the laboratory, both "CVm" and "CUE" were small since emitters were manufactured manually, the manufacturing variation was higher than in processed emitters. Variation in the membrane diameter decreased 1/4.5 from the central toward to the emitter end; and, the head loss increased. Estimated pressures were in good agreement to the observed ones with r and d values of 0.95, and 0.85, respectively. In the field tests, coefficients CVQR and QR were variable showing a poor classification according with ABNT (1986) and Solomon (1984). FD values were ranged between 11 and 24%and there was no observed clogging by roots and/or soil intrusion at the end of the experiment. On the other hand, emitter's flows were close to the average, indicating that water application kept according to the initial results. This study shows the suitability of this emitter model to prevent root and soil intrusion within the research conditions however further studies would be needed assessing the membrane performance, emitter physical characteristics, and control of emitter flow rate in order to develop the final prototype.

  8. Fault location in optical networks

    DOEpatents

    Stevens, Rick C [Apple Valley, MN; Kryzak, Charles J [Mendota Heights, MN; Keeler, Gordon A [Albuquerque, NM; Serkland, Darwin K [Albuquerque, NM; Geib, Kent M [Tijeras, NM; Kornrumpf, William P [Schenectady, NY

    2008-07-01

    One apparatus embodiment includes an optical emitter and a photodetector. At least a portion of the optical emitter extends a radial distance from a center point. The photodetector provided around at least a portion of the optical emitter and positioned outside the radial distance of the portion of the optical emitter.

  9. Measurements of optical properties of some molten oxides

    NASA Astrophysics Data System (ADS)

    Nason, D. O.; Yen, C. T.; Tiller, W. A.

    1990-11-01

    A method based on a fine-focussed optical laser has been developed to measure the spectral reflectance and the transmittance of small ( ∽ 1 mm) liquid or single crystal materials. The measured normal spectral emittance for 633 nm light is about 0.9 for several molten refractory oxides, 0.8 for lithium niobate and 0.7 for molten sapphire. Sapphire and YAG experience a several-fold increase in emittance on melting. The absorption coefficient and the thickness for opaqueness are calculated and some consequences of the partial transparency of small hot materials, when their temperatures are measured by optical pyrometry, are discussed.

  10. Detection of extended galactic sources with an underwater neutrino telescope

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Leisos, A.; Tsirigotis, A. G.; Tzamarias, S. E.

    2014-11-18

    In this study we investigate the discovery capability of a Very Large Volume Neutrino Telescope to Galactic extended sources. We focus on the brightest HESS gamma rays sources which are considered also as very high energy neutrino emitters. We use the unbinned method taking into account both the spatial and the energy distribution of high energy neutrinos and we investigate parts of the Galactic plane where nearby potential neutrino emitters form neutrino source clusters. Neutrino source clusters as well as isolated neutrino sources are combined to estimate the observation period for 5 sigma discovery of neutrino signals from these objects.

  11. Measurement of beta-plus emitters by gamma-ray spectrometry.

    PubMed

    Lépy, Marie-Christine; Cassette, Philippe; Ferreux, Laurent

    2010-01-01

    The activity measurement of beta-plus emitters by gamma-ray spectrometry is studied. Experimental measurements are performed with (22)Na, (65)Zn and (64)Cu with sources included in a lead container. For these nuclides, the activity can be derived both from one photon emission peak and from the 511 keV annihilation peak, including annihilation in-flight correction and geometry correction computed by Monte Carlo simulation. The activity values obtained using the two types of peaks show satisfying agreement. The extension of the method to volume sources is discussed. Copyright 2009 Elsevier Ltd. All rights reserved.

  12. Recovering the triple coincidence of non-pure positron emitters in preclinical PET

    NASA Astrophysics Data System (ADS)

    Lin, Hsin-Hon; Chuang, Keh-Shih; Chen, Szu-Yu; Jan, Meei-Ling

    2016-03-01

    Non-pure positron emitters, with their long half-lives, allow for the tracing of slow biochemical processes which cannot be adequately examined by the commonly used short-lived positron emitters. Most of these isotopes emit high-energy cascade gamma rays in addition to positron decay that can be detected and create a triple coincidence with annihilation photons. Triple coincidence is discarded in most scanners, however, the majority of the triple coincidence contains true photon pairs that can be recovered. In this study, we propose a strategy for recovering triple coincidence events to raise the sensitivity of PET imaging for non-pure positron emitters. To identify the true line of response (LOR) from a triple coincidence, a framework utilizing geometrical, energy and temporal information is proposed. The geometrical criterion is based on the assumption that the LOR with the largest radial offset among the three sub pairs of triple coincidences is least likely to be a true LOR. Then, a confidence time window is used to test the valid LOR among those within triple coincidence. Finally, a likelihood ratio discriminant rule based on the energy probability density distribution of cascade and annihilation gammas is established to identify the true LOR. An Inveon preclinical PET scanner was modeled with GATE (GEANT4 application for tomographic emission) Monte Carlo software. We evaluated the performance of the proposed method in terms of identification fraction, noise equivalent count rates (NECR), and image quality on various phantoms. With the inclusion of triple coincidence events using the proposed method, the NECR was found to increase from 11% to 26% and 19% to 29% for I-124 and Br-76, respectively, when 7.4-185 MBq of activity was used. Compared to the reconstructed images using double coincidence, this technique increased the SNR by 5.1-7.3% for I-124 and 9.3-10.3% for Br-76 within the activity range of 9.25-74 MBq, without compromising the spatial resolution or contrast. We conclude that the proposed method can improve the counting statistics of PET imaging for non-pure positron emitters and is ready to be implemented on current PET systems. Parts of this work were presented at the 2012 Annual Congress of the European Association of Nuclear Medicine.

  13. Hydrothermal method of synthesis of rare-earth tantalates and niobates

    DOEpatents

    Nyman, May D; Rohwer, Lauren E.S.; Martin, James E

    2012-10-16

    A hydrothermal method of synthesis of a family of rare-earth Group 5 oxides, where the Group 5 oxide is a niobate or tantalate. The rare-earth Group 5 oxides can be doped with suitable emitter ions to form nanophosphors.

  14. Realizing Highly Efficient Solution-Processed Homojunction-Like Sky-Blue OLEDs by Using Thermally Activated Delayed Fluorescent Emitters Featuring an Aggregation-Induced Emission Property.

    PubMed

    Wu, Kailong; Wang, Zian; Zhan, Lisi; Zhong, Cheng; Gong, Shaolong; Xie, Guohua; Yang, Chuluo

    2018-04-05

    Two new blue emitters, i.e., bis-[2-(9,9-dimethyl-9,10-dihydroacridine)-phenyl]-sulfone ( o-ACSO2) and bis-[3-(9,9-dimethyl-9,10-dihydroacridine)-phenyl]-sulfone ( m-ACSO2), with reserved fine thermally activated delayed fluorescent (TADF) nature and simply tuned thermal and optoelectronic properties, were synthesized by isomer engineering. The meta-linking compound, i.e., m-ACSO2, obtains the highest photoluminescence quantum yield with a small singlet-triplet energy gap, a moderate delayed fluorescent lifetime, excellent solubility, and neat film homogeneity. Due to its unique aggregation-induced emission (AIE) character, neat film-based heterojunction-like organic light-emitting diodes (OLEDs) are achievable. By inserting an excitonic inert exciton-blocking layer, the PN heterojunction-like emission accompanied by intefacial exciplex was shifted to a homojunction-like channel mainly from the AIE emitter itself, providing a new tactic to generate efficient blue color from neat films. The solution-processed nondoped sky-blue OLED employing m-ACSO2 as emitter with homojunction-like emission achieved a maximum external quantum efficiency of 17.2%. The design strategies presented herein provide practical methods to construct efficient blue TADF dyes and realize high-performance blue TADF devices.

  15. Spontaneous emission in the presence of a realistically sized cylindrical waveguide

    NASA Astrophysics Data System (ADS)

    Dung, Ho Trung

    2016-02-01

    Various quantities characterizing the spontaneous emission process of a dipole emitter including the emission rate and the emission pattern can be expressed in terms of the Green tensor of the surrounding environment. By expanding the Green tensor around some analytically known background one as a Born series, and truncating it under appropriate conditions, complicated boundaries can be tackled with ease. However, when the emitter is embedded in the medium, even the calculation of the first-order term in the Born series is problematic because of the presence of a singularity. We show how to eliminate this singularity for a medium of arbitrary size and shape by expanding around the bulk medium rather than vacuum. In the highly symmetric configuration of an emitter located on the axis of a realistically sized cylinder, it is shown that the singularity can be removed by changing the integral variables and then the order of integration. Using both methods, we investigate the spontaneous emission rate of an initially excited two-level dipole emitter, embedded in a realistically sized cylinder, which can be a common optical fiber in the long-length limit and a disk in the short-length limit. The spatial distribution of the emitted light is calculated using the Born-expansion approach, and local-field corrections to the spontaneous emission rate are briefly discussed.

  16. Multisource inverse-geometry CT. Part II. X-ray source design and prototype

    PubMed Central

    Neculaes, V. Bogdan; Caiafa, Antonio; Cao, Yang; De Man, Bruno; Edic, Peter M.; Frutschy, Kristopher; Gunturi, Satish; Inzinna, Lou; Reynolds, Joseph; Vermilyea, Mark; Wagner, David; Zhang, Xi; Zou, Yun; Pelc, Norbert J.; Lounsberry, Brian

    2016-01-01

    Purpose: This paper summarizes the development of a high-power distributed x-ray source, or “multisource,” designed for inverse-geometry computed tomography (CT) applications [see B. De Man et al., “Multisource inverse-geometry CT. Part I. System concept and development,” Med. Phys. 43, 4607–4616 (2016)]. The paper presents the evolution of the source architecture, component design (anode, emitter, beam optics, control electronics, high voltage insulator), and experimental validation. Methods: Dispenser cathode emitters were chosen as electron sources. A modular design was adopted, with eight electron emitters (two rows of four emitters) per module, wherein tungsten targets were brazed onto copper anode blocks—one anode block per module. A specialized ceramic connector provided high voltage standoff capability and cooling oil flow to the anode. A matrix topology and low-noise electronic controls provided switching of the emitters. Results: Four modules (32 x-ray sources in two rows of 16) have been successfully integrated into a single vacuum vessel and operated on an inverse-geometry computed tomography system. Dispenser cathodes provided high beam current (>1000 mA) in pulse mode, and the electrostatic lenses focused the current beam to a small optical focal spot size (0.5 × 1.4 mm). Controlled emitter grid voltage allowed the beam current to be varied for each source, providing the ability to modulate beam current across the fan of the x-ray beam, denoted as a virtual bowtie filter. The custom designed controls achieved x-ray source switching in <1 μs. The cathode-grounded source was operated successfully up to 120 kV. Conclusions: A high-power, distributed x-ray source for inverse-geometry CT applications was successfully designed, fabricated, and operated. Future embodiments may increase the number of spots and utilize fast read out detectors to increase the x-ray flux magnitude further, while still staying within the stationary target inherent thermal limitations. PMID:27487878

  17. Multisource inverse-geometry CT. Part II. X-ray source design and prototype

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Neculaes, V. Bogdan, E-mail: neculaes@ge.com; Caia

    2016-08-15

    Purpose: This paper summarizes the development of a high-power distributed x-ray source, or “multisource,” designed for inverse-geometry computed tomography (CT) applications [see B. De Man et al., “Multisource inverse-geometry CT. Part I. System concept and development,” Med. Phys. 43, 4607–4616 (2016)]. The paper presents the evolution of the source architecture, component design (anode, emitter, beam optics, control electronics, high voltage insulator), and experimental validation. Methods: Dispenser cathode emitters were chosen as electron sources. A modular design was adopted, with eight electron emitters (two rows of four emitters) per module, wherein tungsten targets were brazed onto copper anode blocks—one anode blockmore » per module. A specialized ceramic connector provided high voltage standoff capability and cooling oil flow to the anode. A matrix topology and low-noise electronic controls provided switching of the emitters. Results: Four modules (32 x-ray sources in two rows of 16) have been successfully integrated into a single vacuum vessel and operated on an inverse-geometry computed tomography system. Dispenser cathodes provided high beam current (>1000 mA) in pulse mode, and the electrostatic lenses focused the current beam to a small optical focal spot size (0.5 × 1.4 mm). Controlled emitter grid voltage allowed the beam current to be varied for each source, providing the ability to modulate beam current across the fan of the x-ray beam, denoted as a virtual bowtie filter. The custom designed controls achieved x-ray source switching in <1 μs. The cathode-grounded source was operated successfully up to 120 kV. Conclusions: A high-power, distributed x-ray source for inverse-geometry CT applications was successfully designed, fabricated, and operated. Future embodiments may increase the number of spots and utilize fast read out detectors to increase the x-ray flux magnitude further, while still staying within the stationary target inherent thermal limitations.« less

  18. Hybrid emitter all back contact solar cell

    DOEpatents

    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.

  19. Demonstration of Current Profile Shaping using Double Dog-Leg Emittance Exchange Beam Line at Argonne Wakefield Accelerator

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ha, Gwanghui; Cho, Moo-Hyun; Conde, Manoel

    Emittance exchange (EEX) based longitudinal current profile shaping is the one of the promising current profile shaping technique. This method can generate high quality arbitrary current profiles under the ideal conditions. The double dog-leg EEX beam line was recently installed at the Argonne Wakefield Accelerator (AWA) to explore the shaping capability and confirm the quality of this method. To demonstrate the arbitrary current profile generation, several different transverse masks are applied to generate different final current profiles. The phase space slopes and the charge of incoming beam are varied to observe and suppress the aberrations on the ideal profile. Wemore » present current profile shaping results, aberrations on the shaped profile, and its suppression.« less

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

    PubMed

    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.

  1. Ion Motion Induced Emittance Growth of Matched Electron Beams in Plasma Wakefields

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    An, Weiming; Lu, Wei; Huang, Chengkun

    2017-06-14

    Plasma-based acceleration is being considered as the basis for building a future linear collider. Nonlinear plasma wakefields have ideal properties for accelerating and focusing electron beams. Preservation of the emittance of nano-Coulomb beams with nanometer scale matched spot sizes in these wakefields remains a critical issue due to ion motion caused by their large space charge forces. We use fully resolved quasistatic particle-in-cell simulations of electron beams in hydrogen and lithium plasmas, including when the accelerated beam has different emittances in the two transverse planes. The projected emittance initially grows and rapidly saturates with a maximum emittance growth of lessmore » than 80% in hydrogen and 20% in lithium. The use of overfocused beams is found to dramatically reduce the emittance growth. In conclusion, the underlying physics that leads to the lower than expected emittance growth is elucidated.« less

  2. Emission Testing Results of Thermally Stable, Metamaterial, Selective-Emitters for Thermophotovoltaics

    NASA Astrophysics Data System (ADS)

    Levinson, Katherine; Naka, Norihito; Pfiester, Nicole; Licht, Abigail; Vandervelde, Tom

    2015-03-01

    In thermophotovoltaics, the energy from a heated emitter is converted to electricity by a photovoltaic diode. A selective emitter can be used to emit a narrow band of wavelengths tailored to the bandgap of the photovoltaic diode. This spectral shaping improves the conversion efficiency of the diode and reduces undesirable diode heating. In our research, we study selective emitters based on metamaterials composed of repeating nanoscale structures. The emission characteristics of these materials vary based on the compositional structure, allowing the emitted spectrum to be tunable. Simulations were performed with CST Microwave Studio to design emitters with peak wavelengths ranging from 1-10 microns. The structures were then fabricated using physical vapor deposition and electron beam lithography on a sapphire substrate. Emitter materials studied include gold, platinum, and iridium. Here we report on the emission spectra of the selective emitters and the post-heating structural integrity.

  3. Comparison of PHITS, GEANT4, and HIBRAC simulations of depth-dependent yields of β(+)-emitting nuclei during therapeutic particle irradiation to measured data.

    PubMed

    Rohling, Heide; Sihver, Lembit; Priegnitz, Marlen; Enghardt, Wolfgang; Fiedler, Fine

    2013-09-21

    For quality assurance in particle therapy, a non-invasive, in vivo range verification is highly desired. Particle therapy positron-emission-tomography (PT-PET) is the only clinically proven method up to now for this purpose. It makes use of the β(+)-activity produced during the irradiation by the nuclear fragmentation processes between the therapeutic beam and the irradiated tissue. Since a direct comparison of β(+)-activity and dose is not feasible, a simulation of the expected β(+)-activity distribution is required. For this reason it is essential to have a quantitatively reliable code for the simulation of the yields of the β(+)-emitting nuclei at every position of the beam path. In this paper results of the three-dimensional Monte-Carlo simulation codes PHITS, GEANT4, and the one-dimensional deterministic simulation code HIBRAC are compared to measurements of the yields of the most abundant β(+)-emitting nuclei for carbon, lithium, helium, and proton beams. In general, PHITS underestimates the yields of positron-emitters. With GEANT4 the overall most accurate results are obtained. HIBRAC and GEANT4 provide comparable results for carbon and proton beams. HIBRAC is considered as a good candidate for the implementation to clinical routine PT-PET.

  4. Comparison of PHITS, GEANT4, and HIBRAC simulations of depth-dependent yields of β+-emitting nuclei during therapeutic particle irradiation to measured data

    NASA Astrophysics Data System (ADS)

    Rohling, Heide; Sihver, Lembit; Priegnitz, Marlen; Enghardt, Wolfgang; Fiedler, Fine

    2013-09-01

    For quality assurance in particle therapy, a non-invasive, in vivo range verification is highly desired. Particle therapy positron-emission-tomography (PT-PET) is the only clinically proven method up to now for this purpose. It makes use of the β+-activity produced during the irradiation by the nuclear fragmentation processes between the therapeutic beam and the irradiated tissue. Since a direct comparison of β+-activity and dose is not feasible, a simulation of the expected β+-activity distribution is required. For this reason it is essential to have a quantitatively reliable code for the simulation of the yields of the β+-emitting nuclei at every position of the beam path. In this paper results of the three-dimensional Monte-Carlo simulation codes PHITS, GEANT4, and the one-dimensional deterministic simulation code HIBRAC are compared to measurements of the yields of the most abundant β+-emitting nuclei for carbon, lithium, helium, and proton beams. In general, PHITS underestimates the yields of positron-emitters. With GEANT4 the overall most accurate results are obtained. HIBRAC and GEANT4 provide comparable results for carbon and proton beams. HIBRAC is considered as a good candidate for the implementation to clinical routine PT-PET.

  5. Doping-free white organic light-emitting diodes without blue molecular emitter: An unexplored approach to achieve high performance via exciplex emission

    NASA Astrophysics Data System (ADS)

    Luo, Dongxiang; Xiao, Ye; Hao, Mingming; Zhao, Yu; Yang, Yibin; Gao, Yuan; Liu, Baiquan

    2017-02-01

    Doping-free white organic light-emitting diodes (DF-WOLEDs) are promising for the low-cost commercialization because of their simplified device structures. However, DF-WOLEDs reported thus far in the literature are based on the use of blue single molecular emitters, whose processing can represent a crucial point in device manufacture. Herein, DF-WOLEDs without the blue single molecular emitter have been demonstrated by managing a blue exciplex system. For the single-molecular-emitter (orange or yellow emitter) DF-WOLEDs, (i) a color rendering index (CRI) of 81 at 1000 cd/m2 can be obtained, which is one of the highest for the single-molecular-emitter WOLEDs, or (ii) a high efficiency of 35.4 lm/W can be yielded. For the dual-molecular-emitter (yellow/red emitters) DF-WOLED, a high CRI of 85 and low correlated color temperature of 2376 K at 1000 cd/m2 have been simultaneously achieved, which has not been reported by previous DF-WOLEDs. Such presented findings may unlock an alternative avenue to the simplified but high-performance WOLEDs.

  6. High-speed and on-chip graphene blackbody emitters for optical communications by remote heat transfer.

    PubMed

    Miyoshi, Yusuke; Fukazawa, Yusuke; Amasaka, Yuya; Reckmann, Robin; Yokoi, Tomoya; Ishida, Kazuki; Kawahara, Kenji; Ago, Hiroki; Maki, Hideyuki

    2018-03-29

    High-speed light emitters integrated on silicon chips can enable novel architectures for silicon-based optoelectronics, such as on-chip optical interconnects, and silicon photonics. However, conventional light sources based on compound semiconductors face major challenges for their integration with a silicon-based platform because of their difficulty of direct growth on a silicon substrate. Here we report ultra-high-speed (100-ps response time), highly integrated graphene-based on-silicon-chip blackbody emitters in the near-infrared region including telecommunication wavelength. Their emission responses are strongly affected by the graphene contact with the substrate depending on the number of graphene layers. The ultra-high-speed emission can be understood by remote quantum thermal transport via surface polar phonons of the substrates. We demonstrated real-time optical communications, integrated two-dimensional array emitters, capped emitters operable in air, and the direct coupling of optical fibers to the emitters. These emitters can open new routes to on-Si-chip, small footprint, and high-speed emitters for highly integrated optoelectronics and silicon photonics.

  7. Thermal emittance enhancement of graphite-copper composites for high temperature space based radiators

    NASA Technical Reports Server (NTRS)

    Rutledge, Sharon K.; Forkapa, Mark J.; Cooper, Jill M.

    1991-01-01

    Graphite-copper composites are candidate materials for space based radiators. The thermal emittance of this material, however, is a factor of two lower than the desired emittance for these systems of greater than or equal to 0.85. Arc texturing was investigated as a surface modification technique for enhancing the emittance of the composite. Since the outer surface of the composite is copper, and samples of the composite could not be readily obtained for testing, copper was used for optimization testing. Samples were exposed to various frequencies and currents of arcs during texturing. Emittances near the desired goal were achieved at frequencies less than 500 Hz. Arc current did not appear to play a major role under 15 amps. Particulate carbon was observed on the surface, and was easily removed by vibration and handling. In order to determine morphology adherence, ultrasonic cleaning was used to remove the loosely adherent material. This reduced the emittance significantly. Emittance was found to increase with increasing frequency for the cleaned samples up to 500 Hz. The highest emittance achieved on these samples over the temperature range of interest was 0.5 to 0.6, which is approximately a factor of 25 increase over the untextured copper emittance.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  9. Vision 20/20: Positron emission tomography in radiation therapy planning, delivery, and monitoring.

    PubMed

    Parodi, Katia

    2015-12-01

    Positron emission tomography (PET) is increasingly considered as an effective imaging method to support several stages of radiation therapy. The combined usage of functional and morphological imaging in state-of-the-art PET/CT scanners is rapidly emerging to support the treatment planning process in terms of improved tumor delineation, and to assess the tumor response in follow-up investigations after or even during the course of fractionated therapy. Moreover, active research is being pursued on new tracers capable of providing different insights into tumor function, in order to identify areas of the planning volume which may require additional dosage for improved probability of tumor control. In this respect, major progresses in the next years will likely concern the development and clinical investigation of novel tracers and image processing techniques for reliable thresholding and segmentation, of treatment planning and beam delivery approaches integrating the PET imaging information, as well as improved multimodal clinical instrumentation such as PET/MR. But especially in the rapidly emerging case of ion beam therapy, the usage of PET is not only limited to the imaging of external tracers injected to the patient. In fact, a minor amount of positron emitters is formed in nuclear fragmentation reactions between the impinging ions and the tissue, bearing useful information for confirmation of the delivered treatment during or after therapeutic irradiation. Different implementations of unconventional PET imaging for therapy monitoring are currently being investigated clinically, and major ongoing research aims at new dedicated detector technologies and at challenging applications such as real-time imaging and time-resolved in vivo verification of motion compensated beam delivery. This paper provides an overview of the different areas of application of PET in radiation oncology and discusses the most promising perspectives in the years to come for radiation therapy planning, delivery, and monitoring.

  10. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Eremenko, D. O.; Fotina, O. V.; Platonov, S. Yu.

    The functional fitness of the alpha-emitter At-211 for radiotherapy of the thyroid gland cancer is evaluated. Radiation doses are calculated using the MIRD method and previously obtained pharmacokinetic data for At-211 in isotonic solution.

  11. The MUSE-Wide survey: detection of a clustering signal from Lyman α emitters in the range 3 < z < 6

    NASA Astrophysics Data System (ADS)

    Diener, C.; Wisotzki, L.; Schmidt, K. B.; Herenz, E. C.; Urrutia, T.; Garel, T.; Kerutt, J.; Saust, R. L.; Bacon, R.; Cantalupo, S.; Contini, T.; Guiderdoni, B.; Marino, R. A.; Richard, J.; Schaye, J.; Soucail, G.; Weilbacher, P. M.

    2017-11-01

    We present a clustering analysis of a sample of 238 Ly α emitters at redshift 3 ≲ z ≲ 6 from the MUSE-Wide survey. This survey mosaics extragalactic legacy fields with 1h MUSE pointings to detect statistically relevant samples of emission line galaxies. We analysed the first year observations from MUSE-Wide making use of the clustering signal in the line-of-sight direction. This method relies on comparing pair-counts at close redshifts for a fixed transverse distance and thus exploits the full potential of the redshift range covered by our sample. A clear clustering signal with a correlation length of r0=2.9^{+1.0}_{-1.1} Mpc (comoving) is detected. Whilst this result is based on only about a quarter of the full survey size, it already shows the immense potential of MUSE for efficiently observing and studying the clustering of Ly α emitters.

  12. Photoinjector optimization using a derivative-free, model-based trust-region algorithm for the Argonne Wakefield Accelerator

    NASA Astrophysics Data System (ADS)

    Neveu, N.; Larson, J.; Power, J. G.; Spentzouris, L.

    2017-07-01

    Model-based, derivative-free, trust-region algorithms are increasingly popular for optimizing computationally expensive numerical simulations. A strength of such methods is their efficient use of function evaluations. In this paper, we use one such algorithm to optimize the beam dynamics in two cases of interest at the Argonne Wakefield Accelerator (AWA) facility. First, we minimize the emittance of a 1 nC electron bunch produced by the AWA rf photocathode gun by adjusting three parameters: rf gun phase, solenoid strength, and laser radius. The algorithm converges to a set of parameters that yield an emittance of 1.08 μm. Second, we expand the number of optimization parameters to model the complete AWA rf photoinjector (the gun and six accelerating cavities) at 40 nC. The optimization algorithm is used in a Pareto study that compares the trade-off between emittance and bunch length for the AWA 70MeV photoinjector.

  13. Scalable focused ion beam creation of nearly lifetime-limited single quantum emitters in diamond nanostructures

    PubMed Central

    Schröder, Tim; Trusheim, Matthew E.; Walsh, Michael; Li, Luozhou; Zheng, Jiabao; Schukraft, Marco; Sipahigil, Alp; Evans, Ruffin E.; Sukachev, Denis D.; Nguyen, Christian T.; Pacheco, Jose L.; Camacho, Ryan M.; Bielejec, Edward S.; Lukin, Mikhail D.; Englund, Dirk

    2017-01-01

    The controlled creation of defect centre—nanocavity systems is one of the outstanding challenges for efficiently interfacing spin quantum memories with photons for photon-based entanglement operations in a quantum network. Here we demonstrate direct, maskless creation of atom-like single silicon vacancy (SiV) centres in diamond nanostructures via focused ion beam implantation with ∼32 nm lateral precision and <50 nm positioning accuracy relative to a nanocavity. We determine the Si+ ion to SiV centre conversion yield to be ∼2.5% and observe a 10-fold conversion yield increase by additional electron irradiation. Low-temperature spectroscopy reveals inhomogeneously broadened ensemble emission linewidths of ∼51 GHz and close to lifetime-limited single-emitter transition linewidths down to 126±13 MHz corresponding to ∼1.4 times the natural linewidth. This method for the targeted generation of nearly transform-limited quantum emitters should facilitate the development of scalable solid-state quantum information processors. PMID:28548097

  14. Scalable focused ion beam creation of nearly lifetime-limited single quantum emitters in diamond nanostructures

    DOE PAGES

    Schroder, Tim; Trusheim, Matthew E.; Walsh, Michael; ...

    2017-05-26

    The controlled creation of defect centre—nanocavity systems is one of the outstanding challenges for efficiently interfacing spin quantum memories with photons for photon-based entanglement operations in a quantum network. Here we demonstrate direct, maskless creation of atom-like single silicon vacancy (SiV) centres in diamond nanostructures via focused ion beam implantation with ~32 nm lateral precision and <50 nm positioning accuracy relative to a nanocavity. We determine the Si+ ion to SiV centre conversion yield to be ~2.5% and observe a 10-fold conversion yield increase by additional electron irradiation. Low-temperature spectroscopy reveals inhomogeneously broadened ensemble emission linewidths of ~51 GHz andmore » close to lifetime-limited single-emitter transition linewidths down to 126±13 MHz corresponding to ~1.4 times the natural linewidth. Furthermore, this method for the targeted generation of nearly transform-limited quantum emitters should facilitate the development of scalable solid-state quantum information processors.« less

  15. Scalable focused ion beam creation of nearly lifetime-limited single quantum emitters in diamond nanostructures

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schroder, Tim; Trusheim, Matthew E.; Walsh, Michael

    The controlled creation of defect centre—nanocavity systems is one of the outstanding challenges for efficiently interfacing spin quantum memories with photons for photon-based entanglement operations in a quantum network. Here we demonstrate direct, maskless creation of atom-like single silicon vacancy (SiV) centres in diamond nanostructures via focused ion beam implantation with ~32 nm lateral precision and <50 nm positioning accuracy relative to a nanocavity. We determine the Si+ ion to SiV centre conversion yield to be ~2.5% and observe a 10-fold conversion yield increase by additional electron irradiation. Low-temperature spectroscopy reveals inhomogeneously broadened ensemble emission linewidths of ~51 GHz andmore » close to lifetime-limited single-emitter transition linewidths down to 126±13 MHz corresponding to ~1.4 times the natural linewidth. Furthermore, this method for the targeted generation of nearly transform-limited quantum emitters should facilitate the development of scalable solid-state quantum information processors.« less

  16. Intrinsic delay of permeable base transistor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, Wenchao; Guo, Jing; So, Franky

    2014-07-28

    Permeable base transistors (PBTs) fabricated by vacuum deposition or solution process have the advantages of easy fabrication and low power operation and are a promising device structure for flexible electronics. Intrinsic delay of PBT, which characterizes the speed of the transistor, is investigated by solving the three-dimensional Poisson equation and drift-diffusion equation self-consistently using finite element method. Decreasing the emitter thickness lowers the intrinsic delay by improving on-current, and a thinner base is also preferred for low intrinsic delay because of fewer carriers in the base region at off-state. The intrinsic delay exponentially decreases as the emitter contact Schottky barriermore » height decreases, and it linearly depends on the carrier mobility. With an optimized emitter contact barrier height and device geometry, a sub-nano-second intrinsic delay can be achieved with a carrier mobility of ∼10 cm{sup 2}/V/s obtainable in solution processed indium gallium zinc oxide, which indicates the potential of solution processed PBTs for GHz operations.« less

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

    PubMed

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

    2016-03-01

    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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Investigation of tenuous plasma environment using Active Spacecraft Potential Control (ASPOC) on Magnetospheric Multiscale (MMS) Mission

    NASA Astrophysics Data System (ADS)

    Nakamura, Rumi; Jeszenszky, Harald; Torkar, Klaus; Andriopoulou, Maria; Fremuth, Gerhard; Taijmar, Martin; Scharlemann, Carsten; Svenes, Knut; Escoubet, Philippe; Prattes, Gustav; Laky, Gunter; Giner, Franz; Hoelzl, Bernhard

    2015-04-01

    The NASA's Magnetospheric Multiscale (MMS) Mission is planned to be launched on March 12, 2015. The scientific objectives of the MMS mission are to explore and understand the fundamental plasma physics processes of magnetic reconnection, particle acceleration and turbulence in the Earth's magnetosphere. The region of scientific interest of MMS is in a tenuous plasma environment where the positive spacecraft potential reaches an equilibrium at several tens of Volts. An Active Spacecraft Potential Control (ASPOC) instrument neutralizes the spacecraft potential by releasing positive charge produced by indium ion emitters. ASPOC thereby reduces the potential in order to improve the electric field and low-energy particle measurement. The method has been successfully applied on other spacecraft such as Cluster and Double Star. Two ASPOC units are present on each of the MMS spacecraft. Each unit contains four ion emitters, whereby one emitter per instrument is operated at a time. ASPOC for MMS includes new developments in the design of the emitters and the electronics enabling lower spacecraft potentials, higher reliability, and a more uniform potential structure in the spacecraft's sheath compared to previous missions. Model calculations confirm the findings from previous applications that the plasma measurements will not be affected by the beam's space charge. A perfectly stable spacecraft potential precludes the utilization of the spacecraft as a plasma probe, which is a conventional technique used to estimate ambient plasma density from the spacecraft potential. The small residual variations of the potential controlled by ASPOC, however, still allow to determine ambient plasma density by comparing two closely separated spacecraft and thereby reconstructing the uncontrolled potential variation from the controlled potential. Regular intercalibration of controlled and uncontrolled potentials is expected to increase the reliability of this new method.

  19. Prediction and design of efficient exciplex emitters for high-efficiency, thermally activated delayed-fluorescence organic light-emitting diodes.

    PubMed

    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.

  20. Thermionic gas switch

    DOEpatents

    Hatch, George L.; Brummond, William A.; Barrus, Donald M.

    1986-01-01

    A temperature responsive thermionic gas switch having folded electron emitting surfaces. An ionizable gas is located between the emitter and an interior surface of a collector, coaxial with the emitter. In response to the temperature exceeding a predetermined level, sufficient electrons are derived from the emitter to cause the gas in the gap between the emitter and collector to become ionized, whereby a very large increase in current in the gap occurs. Due to the folded emitter surface area of the switch, increasing the "on/off" current ratio and adjusting the "on" current capacity is accomplished.

  1. Simulated Performance of the Wisconsin Superconducting Electron Gun

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    R.A. Bosch, K.J. Kleman, R.A. Legg

    2012-07-01

    The Wisconsin superconducting electron gun is modeled with multiparticle tracking simulations using the ASTRA and GPT codes. To specify the construction of the emittance-compensation solenoid, we studied the dependence of the output bunch's emittance upon the solenoid's strength and field errors. We also evaluated the dependence of the output bunch's emittance upon the bunch's initial emittance and the size of the laser spot on the photocathode. The results suggest that a 200-pC bunch with an emittance of about one mm-mrad can be produced for a free-electron laser.

  2. Solar absorptance and thermal emittance of some common spacecraft thermal-control coatings

    NASA Technical Reports Server (NTRS)

    Henninger, J. H.

    1984-01-01

    Solar absorptance and thermal emittance of spacecraft materials are critical parameters in determining spacecraft temperature control. Because thickness, surface preparation, coatings formulation, manufacturing techniques, etc. affect these parameters, it is usually necessary to measure the absorptance and emittance of materials before they are used. Absorptance and emittance data for many common types of thermal control coatings, are together with some sample spectral data curves of absorptance. In some cases for which ultraviolet and particle radiation data are available, the degraded absorptance and emittance values are also listed.

  3. High-Performance Field Emission from a Carbonized Cork.

    PubMed

    Lee, Jeong Seok; Lee, Hak Jun; Yoo, Jae Man; Kim, Taewoo; Kim, Yong Hyup

    2017-12-20

    To broaden the range of application of electron beams, low-power field emitters are needed that are miniature and light. Here, we introduce carbonized cork as a material for field emitters. The light natural cork becomes a graphitic honeycomb upon carbonization, with the honeycomb cell walls 100-200 nm thick and the aspect ratio larger than 100, providing an ideal structure for the field electron emission. Compared to nanocarbon field emitters, the cork emitter produces a high current density and long-term stability with a low turn-on field. The nature of the cork material makes it quite simple to fabricate the emitter. Furthermore, any desired shape of the emitter tailored for the final application can easily be prepared for point, line, or planar emission.

  4. Membrane-Based Emitter for Coupling Microfluidics with Ultrasensitive Nanoelectrospray Ionization-Mass Spectrometry

    PubMed Central

    Sun, Xuefei; Kelly, Ryan T.; Tang, Keqi; Smith, Richard D.

    2011-01-01

    An integrated poly(dimethylsiloxane) (PDMS) membrane-based microfluidic emitter for high performance nanoelectrospray ionization-mass spectrometry (nanoESI-MS) has been fabricated and evaluated. The ~100-μm-thick emitter was created by cutting a PDMS membrane that protrudes beyond the bulk substrate. The reduced surface area at the emitter enhances the electric field and reduces wetting of the surface by the electrospray solvent. As such, the emitter enables highly stable electrosprays at flow rates as low as 10 nL/min, and is compatible with electrospray solvents containing a large organic component (e.g., 90% methanol). This approach enables facile emitter construction, and provides excellent stability, reproducibility and sensitivity, as well as compatibility with multilayer soft lithography. PMID:21657269

  5. Rare-Earth Oxide (Yb2O3) Selective Emitter Fabrication and Evaluation

    NASA Technical Reports Server (NTRS)

    Jennette, Bryan; Gregory, Don A.; Herren, Kenneth; Tucker, Dennis; Smith, W. Scott (Technical Monitor)

    2001-01-01

    This investigation involved the fabrication and evaluation of rare-earth oxide selective emitters. The first goal of this study was to successfully fabricate the selective emitter samples using paper and ceramic materials processing techniques. The resulting microstructure was also analyzed using a Scanning Electron Microscope. All selective emitter samples fabricated for this study were made with ytterbium oxide (Yb2O3). The second goal of this study involved the measurement of the spectral emission and the radiated power of all the selective emitter samples. The final goal of this study involved the direct comparison of the radiated power emitted by the selective emitter samples to that of a standard blackbody at the same temperature and within the same wavelength range.

  6. Solid-state current transformer

    NASA Technical Reports Server (NTRS)

    Farnsworth, D. L. (Inventor)

    1976-01-01

    A signal transformation network which is uniquely characterized to exhibit a very low input impedance while maintaining a linear transfer characteristic when driven from a voltage source and when quiescently biased in the low microampere current range is described. In its simplest form, it consists of a tightly coupled two transistor network in which a common emitter input stage is interconnected directly with an emitter follower stage to provide virtually 100 percent negative feedback to the base input of the common emitter stage. Bias to the network is supplied via the common tie point of the common emitter stage collector terminal and the emitter follower base stage terminal by a regulated constant current source, and the output of the circuit is taken from the collector of the emitter follower stage.

  7. Emittance of positron beams produced in intense laser plasma interaction

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen Hui; Hazi, A.; Link, A.

    2013-01-15

    The first measurement of the emittance of intense laser-produced positron beams has been made. The emittance values were derived through measurements of positron beam divergence and source size for different peak positron energies under various laser conditions. For one of these laser conditions, we used a one dimensional pepper-pot technique to refine the emittance value. The laser-produced positrons have a geometric emittance between 100 and 500 mm{center_dot}mrad, comparable to the positron sources used at existing accelerators. With 10{sup 10}-10{sup 12} positrons per bunch, this low emittance beam, which is quasi-monoenergetic in the energy range of 5-20 MeV, may be usefulmore » as an alternative positron source for future accelerators.« less

  8. Information extraction from FN plots of tungsten microemitters.

    PubMed

    Mussa, Khalil O; Mousa, Marwan S; Fischer, Andreas

    2013-09-01

    Tungsten based microemitter tips have been prepared both clean and coated with dielectric materials. For clean tungsten tips, apex radii have been varied ranging from 25 to 500 nm. These tips were manufactured by electrochemical etching a 0.1 mm diameter high purity (99.95%) tungsten wire at the meniscus of two molar NaOH solution. Composite micro-emitters considered here are consisting of a tungsten core coated with different dielectric materials-such as magnesium oxide (MgO), sodium hydroxide (NaOH), tetracyanoethylene (TCNE), and zinc oxide (ZnO). It is worthwhile noting here, that the rather unconventional NaOH coating has shown several interesting properties. Various properties of these emitters were measured including current-voltage (IV) characteristics and the physical shape of the tips. A conventional field emission microscope (FEM) with a tip (cathode)-screen (anode) separation standardized at 10 mm was used to electrically characterize the electron emitters. The system was evacuated down to a base pressure of ∼10(-8) mbar when baked at up to ∼180 °C overnight. This allowed measurements of typical field electron emission (FE) characteristics, namely the IV characteristics and the emission images on a conductive phosphorus screen (the anode). Mechanical characterization has been performed through a FEI scanning electron microscope (SEM). Within this work, the mentioned experimental results are connected to the theory for analyzing Fowler-Nordheim (FN) plots. We compared and evaluated the data extracted from clean tungsten tips of different radii and determined deviations between the results of different extraction methods applied. In particular, we derived the apex radii of several clean and coated tungsten tips by both SEM imaging and analyzing FN plots. The aim of this analysis is to support the ongoing discussion on recently developed improvements of the theory for analyzing FN plots related to metal field electron emitters, which in particular introduces a new form of intercept correction factors. The results derived demonstrate the applicability of the applied method on needle shaped - i.e. non planar - emitters as well as its limits. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Radiometals as payloads for radioimmunotherapy for lymphoma.

    PubMed

    DeNardo, Gerald L; Kennel, Stephen J; Siegel, Jeffry A; Denardo, Sally J

    2004-10-01

    Because of their remarkable effectiveness in radioimmunotherapy (RIT), 2 anti-CD20 monoclonal antibody (MAb) drugs, one labeled with indium 111 for imaging or yttrium 90 for therapy, and another labeled with iodine I 131 for imaging and therapy, have been approved for use in patients with non-Hodgkin's lymphoma (NHL). Successful RIT for lymphomas is due in large part to the rapid and efficient binding of the targeted MAb to lymphoma cells. Carcinomas are more difficult to access, necessitating novel strategies matched with radionuclides with specific physical properties. Because there are many radionuclides from which to choose, a systematic approach is required to select those preferred for a specific application. Thus far, radionuclides with g emissions for imaging and particulate emissions for therapy have been investigated. Radionuclides of iodine were the first to be used for RIT. Many conventionally radioiodinated MAbs are degraded after endocytosis by target cells, releasing radioiodinated peptides and amino acids. In contrast, radiometals have been shown to have residualizing properties, advantageous when the MAb is localized in malignant tissue. b-emitting lanthanides like those of 90Y, lutetium 177, etc. have attractive combinations of biologic, physical, radiochemical, production, economic, and radiation safety characteristics. Other radiometals, such as copper-67 and copper-64, are also of interest. a-emitters, including actinium-225 and bismuth-213, have been used for therapy in selected applications. Evidence for the impact of the radionuclide is provided by data from the randomized pivotal phase III trial of 90Y ibritumomab tiuxetan (Zevalin) in patients with NHL; responses were about 2 times greater in the 90Y ibritumomab tiuxetan arm than in the rituximab arm. It is clear that RIT has emerged as a safe and efficient method for treatment of NHL, especially in specific settings.

  10. Preliminary results of an in-beam PET prototype for proton therapy

    NASA Astrophysics Data System (ADS)

    Attanasi, F.; Belcari, N.; Camarda, M.; Cirrone, G. A. P.; Cuttone, G.; Del Guerra, A.; Di Rosa, F.; Lanconelli, N.; Rosso, V.; Russo, G.; Vecchio, S.

    2008-06-01

    Proton therapy can overcome the limitations of conventional radiotherapy due to the more selective energy deposition in depth and to the increased biological effectiveness. Verification of the delivered dose is desirable, but the complete stopping of the protons in patient prevents the application of electronic portal imaging methods that are used in conventional radiotherapy During proton therapy β + emitters like 11C, 15O, 10C are generated in irradiated tissues by nuclear reactions. The measurement of the spatial distribution of this activity, immediately after patient irradiation, can lead to information on the effective delivered dose. First, results of a feasibility study of an in-beam PET for proton therapy are reported. The prototype is based on two planar heads with an active area of about 5×5 cm 2. Each head is made up of a position sensitive photomultiplier coupled to a square matrix of same size of LYSO scintillating crystals (2×2×18 mm 3 pixel dimensions). Four signals from each head are acquired through a dedicated electronic board that performs signal amplification and digitization. A 3D reconstruction of the activity distribution is calculated using an expectation maximization algorithm. To characterize the PET prototype, the detection efficiency and the spatial resolution were measured using a point-like radioactive source. The validation of the prototype was performed using 62 MeV protons at the CATANA beam line of INFN LNS and PMMA phantoms. Using the full energy proton beam and various range shifters, a good correlation between the position of the activity distal edge and the thickness of the beam range shifter was found along the axial direction.

  11. Using antennas separated in flight direction to avoid effect of emitter clock drift in geolocation

    DOEpatents

    Ormesher, Richard C.; Bickel, Douglas L

    2012-10-23

    The location of a land-based radio frequency (RF) emitter is determined from an airborne platform. RF signaling is received from the RF emitter via first and second antennas. In response to the received RF signaling, signal samples for both antennas are produced and processed to determine the location of the RF emitter.

  12. Efficient triplet harvesting of hybrid white organic light-emitting diodes using thermally activated delayed fluorescence green emitter

    NASA Astrophysics Data System (ADS)

    Lee, Song Eun; Lee, Ho Won; Baek, Hyun Jung; Yun, Tae Jun; Yun, Geum Jae; Kim, Woo Young; Kim, Young Kwan

    2016-10-01

    Hybrid white organic light-emitting diodes (WOLEDs) were fabricated by applying triplet harvesting (TH) using a green thermally activated delayed fluorescence (TADF) emitter. The triplet exciton of the green TADF emitter can be upconverted to its singlet state. The TH involved energy transfer of triplet exciton from a blue fluorescent emitter to a green TADF and red phosphorescent emitters, where they can decay radiatively. In addition, the triplet exciton of the green TADF emitter was energy transferred to its singlet state for a reverse intersystem crossing by green emission. Enhanced hybrid WOLEDs were demonstrated using an efficient green TADF emitter combined with red phosphorescent and blue fluorescent emitters. Hybrid WOLEDs were fabricated with various hole-electron recombination zones as changing blue emitting layer thicknesses. Among these, hybrid WOLEDs showed a maximum external quantum efficiency of 11.23%, luminous efficiency of 29.20 cd/A, and a power efficiency of 26.21 lm/W. Moreover, the WOLED exhibited electroluminescence spectra with Commission International de L'Éclairage chromaticity of (0.38, 0.36) at 1000 cd/m2 and a color rendering index of 82 at a practical brightness of 20,000 cd/m2.

  13. Dynamical theory of single-photon transport in a one-dimensional waveguide coupled to identical and nonidentical emitters

    NASA Astrophysics Data System (ADS)

    Liao, Zeyang; Nha, Hyunchul; Zubairy, M. Suhail

    2016-11-01

    We develop a general dynamical theory for studying a single-photon transport in a one-dimensional (1D) waveguide coupled to multiple emitters which can be either identical or nonidentical. In this theory, both the effects of the waveguide and non-waveguide vacuum modes are included. This theory enables us to investigate the propagation of an emitter excitation or an arbitrary single-photon pulse along an array of emitters coupled to a 1D waveguide. The dipole-dipole interaction induced by the non-waveguide modes, which is usually neglected in the literature, can significantly modify the dynamics of the emitter system as well as the characteristics of the output field if the emitter separation is much smaller than the resonance wavelength. Nonidentical emitters can also strongly couple to each other if their energy difference is less than or of the order of the dipole-dipole energy shift. Interestingly, if their energy difference is close but nonzero, a very narrow transparency window around the resonance frequency can appear which does not occur for identical emitters. This phenomenon may find important applications in quantum waveguide devices such as optical switches and ultranarrow single-photon frequency comb generator.

  14. Extinction Correction Significantly Influences the Estimate of the Lyα Escape Fraction

    NASA Astrophysics Data System (ADS)

    An, Fang Xia; Zheng, Xian Zhong; Hao, Cai-Na; Huang, Jia-Sheng; Xia, Xiao-Yang

    2017-02-01

    The Lyα escape fraction is a key measure to constrain the neutral state of the intergalactic medium and then to understand how the universe was fully reionized. We combine deep narrowband imaging data from the custom-made filter NB393 and the {{{H}}}2S1 filter centered at 2.14 μm to examine the Lyα emitters and Hα emitters at the same redshift z = 2.24. The combination of these two populations allows us to determine the Lyα escape fraction at z = 2.24. Over an area of 383 arcmin2 in the Extended Chandra Deep Field South (ECDFS), 124 Lyα emitters are detected down to NB393 = 26.4 mag at the 5σ level, and 56 Hα emitters come from An et al. Of these, four have both Lyα and Hα emissions (LAHAEs). We also collect the Lyα emitters and Hα emitters at z = 2.24 in the COSMOS field from the literature, and increase the number of LAHAEs to 15 in total. About one-third of them are AGNs. We measure the individual/volumetric Lyα escape fraction by comparing the observed Lyα luminosity/luminosity density to the extinction-corrected Hα luminosity/luminosity density. We revisit the extinction correction for Hα emitters using the Galactic extinction law with color excess for nebular emission. We also adopt the Calzetti extinction law together with an identical color excess for stellar and nebular regions to explore how the uncertainties in extinction correction affect the estimate of individual and global Lyα escape fractions. In both cases, an anti-correlation between the Lyα escape fraction and dust attenuation is found among the LAHAEs, suggesting that dust absorption is responsible for the suppression of the escaping Lyα photons. However, the estimated Lyα escape fraction of individual LAHAEs varies by up to ˜3 percentage points between the two methods of extinction correction. We find the global Lyα escape fraction at z = 2.24 to be (3.7 ± 1.4)% in the ECDFS. The variation in the color excess of the extinction causes a discrepancy of ˜1 percentage point in the global Lyα escape fraction.

  15. SU-E-J-03: A Comprehensive Comparison Between Alpha and Beta Emitters for Cancer Radioimmunotherapy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Huang, C.Y.; Guatelli, S; Oborn, B

    2014-06-01

    Purpose: The purpose of this study is to perform a comprehensive comparison of the therapeutic efficacy and cytotoxicity of alpha and beta emitters for Radioimmunotherapy (RIT). For each stage of cancer development, specific models were built for the separate objectives of RIT to be addressed:a) kill isolated cancer cells in transit in the lymphatic and vascular circulation,b) regress avascular cell clusters,c) regress tumor vasculature and tumors. Methods: Because of the nature of short range, high LET alpha and long energy beta radiation and heterogeneous antigen expression among cancer cells, the microdosimetric approach is essential for the RIT assessment. Geant4 basedmore » microdosimetric models are developed for the three different stages of cancer progression: cancer cells, cell clusters and tumors. The energy deposition, specific energy resulted from different source distribution in the three models was calculated separately for 4 alpha emitting radioisotopes ({sup 211}At, {sup 213}Bi, {sup 223}Ra and {sup 225}Ac) and 6 beta emitters ({sup 32}P, {sup 33}P, {sup 67}Cu, {sup 90}Y, {sup 131}I and {sup 177}Lu). The cell survival, therapeutic efficacy and cytotoxicity are determined and compared between alpha and beta emitters. Results: We show that internal targeted alpha radiation has advantages over beta radiation for killing isolated cancer cells, regressing small cell clusters and also solid tumors. Alpha particles have much higher dose specificity and potency than beta particles. They can deposit 3 logs more dose than beta emitters to single cells and solid tumor. Tumor control probability relies on deep penetration of radioisotopes to cancer cell clusters and solid tumors. Conclusion: The results of this study provide a quantitative understanding of the efficacy and cytotoxicity of RIT for each stage of cancer development.« less

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

    PubMed Central

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

    2015-01-01

    The application of plasmonics to thermal emitters is generally assisted by absorptive losses in the metal because Kirchhoff’s law prescribes that only good absorbers make good thermal emitters. Based on a designed plasmonic crystal and exploiting a slow-wave lattice resonance and spontaneous thermal plasmon emission, we engineer a tungsten-based thermal emitter, fabricated in an industrial CMOS process, and demonstrate its markedly improved practical use in a prototype non-dispersive infrared (NDIR) gas-sensing device. We show that the emission intensity of the thermal emitter at the CO2 absorption wavelength is enhanced almost 4-fold compared to a standard non-plasmonic emitter, which enables a proportionate increase in the signal-to-noise ratio of the CO2 gas sensor. PMID:26639902

  17. Radiative Performance of Rare Earth Garnet Thin Film Selective Emitters

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    In this paper we present the first emitter efficiency results for the thin film 40 percent Er-1.5 percent Ho YAG (Yttrium Aluminum Garnet, Y3Al5O12) and 25 percent Ho YAG selective emitter at 1500 K with a platinum substrate. Spectral emittance and emissive power measurements were made (1.2 less than lambda less than 3.2 microns). Emitter efficiency and power density are significantly improved with the addition of multiple rare earth dopants. Predicted efficiency results are presented for an optimized (equal power density in the Er, (4)I(sub 15/2)-(4)I(sub 13/2) at 1.5 microns, and Ho, (5)I(sub 7)-(5)I(sub 8) at 2.0 micron emission bands) Er-Ho YAG thin film selective emitter.

  18. Emittance of a finite scattering medium with refractive index greater than unity

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Crosbie, A.L.

    1980-01-01

    Refractive index and scattering can significantly influence the transfer of radiation in a semitransparent medium such as water, glass, plastics, or ceramics. In a recent article (1979), the author presented exact numerical results for the emittance of a semiinfinite scattering medium with a refractive index greater than unity. The present investigation extends the analysis to a finite medium. The physical situation consists of a finite planar layer. The isothermal layer emits, absorbs, and isotropically scatters thermal radiation. It is characterized by single scattering albedo, optical thickness, refractive index, and temperature. A formula for the directional emittance is derived, the directionalmore » emittance being the emittance of the medium multiplied by the interface transmittance. The ratio of hemispherical to normal emittance is tabulated and discussed.« less

  19. Fabricating solar cells with silicon nanoparticles

    DOEpatents

    Loscutoff, Paul; Molesa, Steve; Kim, Taeseok

    2014-09-02

    A laser contact process is employed to form contact holes to emitters of a solar cell. Doped silicon nanoparticles are formed over a substrate of the solar cell. The surface of individual or clusters of silicon nanoparticles is coated with a nanoparticle passivation film. Contact holes to emitters of the solar cell are formed by impinging a laser beam on the passivated silicon nanoparticles. For example, the laser contact process may be a laser ablation process. In that case, the emitters may be formed by diffusing dopants from the silicon nanoparticles prior to forming the contact holes to the emitters. As another example, the laser contact process may be a laser melting process whereby portions of the silicon nanoparticles are melted to form the emitters and contact holes to the emitters.

  20. Boric acid solution concentration influencing p-type emitter formation in n-type crystalline Si solar cells

    NASA Astrophysics Data System (ADS)

    Singha, Bandana; Singh Solanki, Chetan

    2016-09-01

    Boric acid (BA) is a spin on dopant (BSoD) source which is used to form p+ emitters in n-type c-Si solar cells. High purity boric acid powder (99.99% pure) when mixed with deionized (DI) water can result in high quality p-type emitter with less amount of surface defects. In this work, we have used different concentrations of boric acid solution concentrations to fabricate p-type emitters with sheet resistance values < 90 Ω/□. The corresponding junction depths for the same are less than 500 nm as measured by SIMS analysis. Boron rich layer (BRL), which is considered as detrimental in emitter performance is found to be minimal for BA solution concentration less than 2% and hence useful for p-type emitter formation.

  1. Pulsed hybrid field emitter

    DOEpatents

    Sampayan, Stephen E.

    1998-01-01

    A hybrid emitter exploits the electric field created by a rapidly depoled ferroelectric material. Combining the emission properties of a planar thin film diamond emitter with a ferroelectric alleviates the present technological problems associated with both types of emitters and provides a robust, extremely long life, high current density cathode of the type required by emerging microwave power generation, accelerator technology and display applications. This new hybrid emitter is easy to fabricate and not susceptible to the same failures which plague microstructure field emitter technology. Local electrode geometries and electric field are determined independently from those for optimum transport and brightness preservation. Due to the large amount of surface charge created on the ferroelectric, the emitted electrons have significant energy, thus eliminating the requirement for specialized phosphors in emissive flat-panel displays.

  2. Pulsed hybrid field emitter

    DOEpatents

    Sampayan, S.E.

    1998-03-03

    A hybrid emitter exploits the electric field created by a rapidly depoled ferroelectric material. Combining the emission properties of a planar thin film diamond emitter with a ferroelectric alleviates the present technological problems associated with both types of emitters and provides a robust, extremely long life, high current density cathode of the type required by emerging microwave power generation, accelerator technology and display applications. This new hybrid emitter is easy to fabricate and not susceptible to the same failures which plague microstructure field emitter technology. Local electrode geometries and electric field are determined independently from those for optimum transport and brightness preservation. Due to the large amount of surface charge created on the ferroelectric, the emitted electrons have significant energy, thus eliminating the requirement for specialized phosphors in emissive flat-panel displays. 11 figs.

  3. Fibrous selective emitter structures from sol-gel process

    NASA Astrophysics Data System (ADS)

    Chen, K. C.

    1999-03-01

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

  4. Experimental studies on coherent synchrotron radiation at an emittance exchange beam line

    NASA Astrophysics Data System (ADS)

    Thangaraj, J. C. T.; Thurman-Keup, R.; Ruan, J.; Johnson, A. S.; Lumpkin, A. H.; Santucci, J.

    2012-11-01

    One of the goals of the Fermilab A0 photoinjector is to investigate experimentally the transverse to longitudinal emittance exchange (EEX) principle. Coherent synchrotron radiation in the emittance exchange line could limit the performance of the emittance exchanger at short bunch lengths. In this paper, we present experimental and simulation studies of the coherent synchrotron radiation (CSR) in the emittance exchange line at the A0 photoinjector. We report on time-resolved CSR studies using a skew-quadrupole technique. We also demonstrate the advantages of running the EEX with an energy-chirped beam.

  5. Emittance Effects on Gain in $W$ -Band TWTs

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Carlsten, Bruce Eric; Nichols, Kimberley E.; Shchegolkov, Dmitry Yu.

    We consider the main effects of beam emittance on W-band traveling-wave tube (TWT) performance and gain. Specifically, we consider a representative dielectric TWT structure with ~5 dB/cm of gain driven by a 5-A, 20-keV, sheet electron beam that is focused by a wiggler magnetic field. The normalized beam transverse emittance must be about 1 μm or lower to ensure that both the transport is stable and the gain is not degraded by the effective energy spread arising from the emittance. This emittance limit scales roughly inversely with frequency.

  6. Emittance Effects on Gain in $W$ -Band TWTs

    DOE PAGES

    Carlsten, Bruce Eric; Nichols, Kimberley E.; Shchegolkov, Dmitry Yu.; ...

    2016-10-20

    We consider the main effects of beam emittance on W-band traveling-wave tube (TWT) performance and gain. Specifically, we consider a representative dielectric TWT structure with ~5 dB/cm of gain driven by a 5-A, 20-keV, sheet electron beam that is focused by a wiggler magnetic field. The normalized beam transverse emittance must be about 1 μm or lower to ensure that both the transport is stable and the gain is not degraded by the effective energy spread arising from the emittance. This emittance limit scales roughly inversely with frequency.

  7. Quantum memory and gates using a Λ -type quantum emitter coupled to a chiral waveguide

    NASA Astrophysics Data System (ADS)

    Li, Tao; Miranowicz, Adam; Hu, Xuedong; Xia, Keyu; Nori, Franco

    2018-06-01

    By coupling a Λ -type quantum emitter to a chiral waveguide, in which the polarization of a photon is locked to its propagation direction, we propose a controllable photon-emitter interface for quantum networks. We show that this chiral system enables the swap gate and a hybrid-entangling gate between the emitter and a flying single photon. It also allows deterministic storage and retrieval of single-photon states with high fidelities and efficiencies. In short, this chirally coupled emitter-photon interface can be a critical building block toward a large-scale quantum network.

  8. The Effect of Temperature on the Radiative Performance of Ho-Yag Thin Film Selective Emitters

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    We present the emitter efficiency results for the thin film 25 percent Ho YAG (Yttrium Aluminum Garnet, Y3Al5O12) selective emitter from 1000 to 1700 K with a platinum substrate. Spectral emittance and emissive power measurements were made (1.2 less than lambda less than 3.2 microns) and used to calculate the radiative efficiency. The radiative efficiency and power density of rare earth doped selective emitters are strongly dependent on temperature and experimental results indicate an optimum temperature (1650 K for Ho YAG) for thermophotovoltaic (TPV) applications.

  9. Wedge Absorbers for Final Cooling for a High-Energy High-Luminosity Lepton Collider

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Neuffer, David; Mohayai, Tanaz; Snopok, Pavel

    2016-06-01

    A high-energy high-luminosity muon collider scenario requires a "final cooling" system that reduces transverse emittance to ~25 microns (normalized) while allowing longitudinal emittance increase. Ionization cooling using high-field solenoids (or Li Lens) can reduce transverse emittances to ~100 microns in readily achievable configurations, confirmed by simulation. Passing these muon beams at ~100 MeV/c through cm-sized diamond wedges can reduce transverse emittances to ~25 microns, while increasing longitudinal emittance by a factor of ~5. Implementation will require optical matching of the exiting beam into downstream acceleration systems.

  10. Development of chemically vapor deposited rhenium emitters of (0001) preferred crystal orientation

    NASA Technical Reports Server (NTRS)

    Yang, L.; Hudson, R. G.

    1973-01-01

    Rhenium thermionic emitters were prepared by the pyrolysis of rhenium chlorides formed by the chlorination of rhenium pellets. The impurity contents, microstructures, degrees of (0001) preferred crystal orientation, and vacuum electron work functions of these emitters were determined as a function of deposition parameters, such as substrate temperature, rhenium pellet temperature and chlorine flow rate. A correlation between vacuum electron work function and degree of (0001) preferred crystal orientation was established. Conditions for depositing porosity-free rhenium emitters of high vacuum electron work functions were defined. Finally, three cylindrical rhenium emitters were prepared under the optimum deposition conditions.

  11. Local Control of Lung Derived Tumors by Diffusing Alpha-Emitting Atoms Released From Intratumoral Wires Loaded With Radium-224

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cooks, Tomer; Schmidt, Michael; Bittan, Hadas

    2009-07-01

    Purpose: Diffusing alpha-emitters radiation therapy (DART) is a new form of brachytherapy enabling the treatment of solid tumors with alpha radiation. The present study examines the antitumoral effects resulting from the release of alpha emitting radioisotopes into solid lung carcinoma (LL2, A427, and NCI-H520). Methods and Materials: An in vitro setup tested the dose-dependent killing of tumor cells exposed to alpha particles. In in vivo studies, radioactive wires (0.3 mm diameter, 5 mm long) with {sup 224}Ra activities in the range of 21-38 kBq were inserted into LL/2 tumors in C57BL/6 mice and into human-derived A427 or NCI-H520 tumors inmore » athymic mice. The efficacy of the short-lived daughters of {sup 224}Ra to produce tumor growth retardation and prolong life was assessed, and the spread of radioisotopes inside tumors was measured using autoradiography. Results: The insertion of a single DART wire into the center of 6- to 7-mm tumors had a pronounced retardation effect on tumor growth, leading to a significant inhibition of 49% (LL2) and 93% (A427) in tumor development and prolongations of 48% (LL2) in life expectancy. In the human model, more than 80% of the treated tumors disappeared or shrunk. Autoradiographic analysis of the treated sectioned tissue revealed the intratumoral distribution of the radioisotopes, and histological analysis showed corresponding areas of necrosis. In vitro experiments demonstrated a dose-dependent killing of tumors cells exposed to alpha particles. Conclusions: Short-lived diffusing alpha-emitters produced tumor growth retardation and increased survival in mice bearing lung tumor implants. These results justify further investigations with improved dose distributions.« less

  12. Alpha voltaic batteries and methods thereof

    NASA Technical Reports Server (NTRS)

    Jenkins, Phillip (Inventor); Scheiman, David (Inventor); Castro, Stephanie (Inventor); Raffaelle, Ryne P. (Inventor); Wilt, David (Inventor); Chubb, Donald (Inventor)

    2011-01-01

    An alpha voltaic battery includes at least one layer of a semiconductor material comprising at least one p/n junction, at least one absorption and conversion layer on the at least one layer of semiconductor layer, and at least one alpha particle emitter. The absorption and conversion layer prevents at least a portion of alpha particles from the alpha particle emitter from damaging the p/n junction in the layer of semiconductor material. The absorption and conversion layer also converts at least a portion of energy from the alpha particles into electron-hole pairs for collection by the one p/n junction in the layer of semiconductor material.

  13. Miniaturized High-Speed Modulated X-Ray Source

    NASA Technical Reports Server (NTRS)

    Gendreau, Keith C. (Inventor); Arzoumanian, Zaven (Inventor); Kenyon, Steven J. (Inventor); Spartana, Nick Salvatore (Inventor)

    2015-01-01

    A miniaturized high-speed modulated X-ray source (MXS) device and a method for rapidly and arbitrarily varying with time the output X-ray photon intensities and energies. The MXS device includes an ultraviolet emitter that emits ultraviolet light, a photocathode operably coupled to the ultraviolet light-emitting diode that emits electrons, an electron multiplier operably coupled to the photocathode that multiplies incident electrons, and an anode operably coupled to the electron multiplier that is configured to produce X-rays. The method for modulating MXS includes modulating an intensity of an ultraviolet emitter to emit ultraviolet light, generating electrons in response to the ultraviolet light, multiplying the electrons to become more electrons, and producing X-rays by an anode that includes a target material configured to produce X-rays in response to impact of the more electrons.

  14. Apparatus for and method of monitoring for breached fuel elements

    DOEpatents

    Gross, Kenny C.; Strain, Robert V.

    1983-01-01

    This invention teaches improved apparatus for the method of detecting a breach in cladded fuel used in a nuclear reactor. The detector apparatus uses a separate bypass loop for conveying part of the reactor coolant away from the core, and at least three separate delayed-neutron detectors mounted proximate this detector loop. The detectors are spaced apart so that the coolant flow time from the core to each detector is different, and these differences are known. The delayed-neutron activity at the detectors is a function of the dealy time after the reaction in the fuel until the coolant carrying the delayed-neutron emitter passes the respective detector. This time delay is broken down into separate components including an isotopic holdup time required for the emitter to move through the fuel from the reaction to the coolant at the breach, and two transit times required for the emitter now in the coolant to flow from the breach to the detector loop and then via the loop to the detector. At least two of these time components are determined during calibrated operation of the reactor. Thereafter during normal reactor operation, repeated comparisons are made by the method of regression approximation of the third time component for the best-fit line correlating measured delayed-neutron activity against activity that is approximated according to specific equations. The equations use these time-delay components and known parameter values of the fuel and of the part and emitting daughter isotopes.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  16. The cataphoretic emitter effect exhibited in high intensity discharge lamp electrodes

    NASA Astrophysics Data System (ADS)

    Mentel, Juergen

    2018-01-01

    A mono-layer of atoms, electropositive with respect to the substrate atoms, forms a dipole layer, reducing its work function. Such a layer is generated by diffusion of emitter material from the interior of the substrate, by vapour deposition or by deposition of emitter material onto arc electrodes by cataphoresis. This cataphoretic emitter effect is investigated within metal halide lamps with transparent YAG ceramic burners, and within model lamps. Within the YAG lamps, arcs are operated with switched-dc current between rod shaped tungsten electrodes in high pressure Hg vapour seeded with metal iodides. Within the model lamps, dc arcs are operated between rod-shaped tungsten electrodes—one doped—in atmospheric pressure Ar. Electrode temperatures are determined by 1λ -pyrometry, combined with simulation of the electrode heat balance. Plasma temperatures, atom and ion densities of emitter material are determined by emission and absorption spectroscopy. Phase resolved measurements in YAG lamps seeded with CeI3, CsI, DyI3, TmI3 and LaI3 show, within the cathodic half period, a reduction of the electrode temperature and an enhanced metal ion density in front of the electrode, and an opposite behavior after phase reversal. With increasing operating frequency, the state of the cathode overlaps onto the anodic phase—except for Cs, being low in adsorption energy. Generally, the phase averaged electrode tip temperature is reduced by seeding a lamp with emitter material; its height depends on admixtures. Measurements at tungsten electrodes doped with ThO2, La2O3 and Ce2O3 within the model lamp show that evaporated emitter material is redeposited by an emitter ion current onto the electrode surface. It reduces the work function of tungsten cathodes above the evaporation temperature of the emitter material, too; and also of cold anodes, indicating a field reversal in front of them. The formation of an emitter spot at low cathode temperature and high emitter material density is traced back to a locally reduced work function generated by a locally enhanced emitter ion current density.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

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

    2011-03-01

    The Fermilab A0 Photoinjector is a 16 MeV high intensity, high brightness electron linac developed for advanced accelerator R&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 includingmore » 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.« less

  18. A design study of the energy selection system for carbon-ion therapy

    NASA Astrophysics Data System (ADS)

    Hahn, Garam; An, Dong Hyun; Hong, Bong Hwan; Kim, Geun Beom; Yim, Heejoong; Chang, Hong Seok; Jung, In Su; Kang, Kun Uk; Nam, Sang Hoon; Park, Inkyu

    2015-02-01

    KHIMA, a research project to construct a carbon radio-therapy facility in Korea, has been developing a superconducting cyclotron named KIRAMS-430 as a carbon(12 C 6+) particle accelerator. Due to the fixed beam energy of the cyclotron, an energy selection system (ESS) is required for treatment of tumors located at various depths in the human body. In the present paper, two design stages of the ESS are discussed. First, the beam tracks behind the degrader block and the statistical twiss parameters for the entire energy range were calculated by using the GEANT4 simulation toolkit. Analysis of the beam transmission and the contamination ratios were performed. In the second stage, the beam optics was designed to support the same phase profile at the end regardless of the variations in all of input twiss parameters and the emittance.

  19. Strong coupling of collection of emitters on hyperbolic meta-material

    NASA Astrophysics Data System (ADS)

    Biehs, Svend-Age; Xu, Chenran; Agarwal, Girish S.

    2018-04-01

    Recently, considerable effort has been devoted to the realization of a strong coupling regime of the radiation matter interaction in the context of an emitter at a meta surface. The strong interaction is well realized in cavity quantum electrodynamics, which also show that strong coupling is much easier to realize using a collection of emitters. Keeping this in mind, we study if emitters on a hyperbolic meta materials can yield a strong coupling regime. We show that strong coupling can be realized for densities of emitters exceeding a critical value. A way to detect strong coupling between emitters and hyperbolic metamaterials is to use the Kretschman-Raether configuration. The strong coupling appears as the splitting of the reflectivity dip. In the weak coupling regime, the dip position shifts. The shift and splitting can be used to sense active molecules at surfaces.

  20. Robust Radar Emitter Recognition Based on the Three-Dimensional Distribution Feature and Transfer Learning

    PubMed Central

    Yang, Zhutian; Qiu, Wei; Sun, Hongjian; Nallanathan, Arumugam

    2016-01-01

    Due to the increasing complexity of electromagnetic signals, there exists a significant challenge for radar emitter signal recognition. To address this challenge, multi-component radar emitter recognition under a complicated noise environment is studied in this paper. A novel radar emitter recognition approach based on the three-dimensional distribution feature and transfer learning is proposed. The cubic feature for the time-frequency-energy distribution is proposed to describe the intra-pulse modulation information of radar emitters. Furthermore, the feature is reconstructed by using transfer learning in order to obtain the robust feature against signal noise rate (SNR) variation. Last, but not the least, the relevance vector machine is used to classify radar emitter signals. Simulations demonstrate that the approach proposed in this paper has better performances in accuracy and robustness than existing approaches. PMID:26927111

  1. Deterministic Coupling of Quantum Emitters in 2D Materials to Plasmonic Nanocavity Arrays.

    PubMed

    Tran, Toan Trong; Wang, Danqing; Xu, Zai-Quan; Yang, Ankun; Toth, Milos; Odom, Teri W; Aharonovich, Igor

    2017-04-12

    Quantum emitters in two-dimensional materials are promising candidates for studies of light-matter interaction and next generation, integrated on-chip quantum nanophotonics. However, the realization of integrated nanophotonic systems requires the coupling of emitters to optical cavities and resonators. In this work, we demonstrate hybrid systems in which quantum emitters in 2D hexagonal boron nitride (hBN) are deterministically coupled to high-quality plasmonic nanocavity arrays. The plasmonic nanoparticle arrays offer a high-quality, low-loss cavity in the same spectral range as the quantum emitters in hBN. The coupled emitters exhibit enhanced emission rates and reduced fluorescence lifetimes, consistent with Purcell enhancement in the weak coupling regime. Our results provide the foundation for a versatile approach for achieving scalable, integrated hybrid systems based on low-loss plasmonic nanoparticle arrays and 2D materials.

  2. Impact of dopant concentrations on emitter formation with spin on dopant source in n-type crystalline silicon solar cells

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Singha, Bandana; Solanki, Chetan Singh

    Use of a suitable dopant source for emitter formation is an essential requirement in n-type crystalline silicon solar cells. Boron spin on dopant source, used as alternative to mostly used BBr{sub 3} liquid source, can yield an emitter with less diffusion induced defects under controlled conditions. Different concentrations of commercially available spin on dopant source is used and optimized in this work for sheet resistance values of the emitter ranging from 30 Ω/□ to 70 Ω/□ with emitter doping concentrations suitable for ohmic contacts. The dopant concentrations diluted with different ratios improves the carrier lifetime and thus improves the emittermore » performance. Hence use of suitable dopant source is essential in forming emitters in n-type crystalline silicon solar cells.« less

  3. Coupling Correction and Beam Dynamics at Ultralow Vertical Emittance in the ALS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Steier, Christoph; Robin, D.; Wolski, A.

    2008-03-17

    For synchrotron light sources and for damping rings of linear colliders it is important to be able to minimize the vertical emittance and to correct the spurious vertical dispersion. This allows one to maximize the brightness and/or the luminosity. A commonly used tool to measure the skew error distribution is the analysis of orbit response matrices using codes like LOCO. Using the new Matlab version of LOCO and 18 newly installed power supplies for individual skew quadrupoles at the ALS the emittance ratio could be reduced below 0.1% at 1.9 GeV yielding a vertical emittance of about 5 pm. Atmore » those very low emittances, additional effects like intra beam scattering become more important, potentially limiting the minimum emittance for machine like the damping rings of linear colliders.« less

  4. Robust Radar Emitter Recognition Based on the Three-Dimensional Distribution Feature and Transfer Learning.

    PubMed

    Yang, Zhutian; Qiu, Wei; Sun, Hongjian; Nallanathan, Arumugam

    2016-02-25

    Due to the increasing complexity of electromagnetic signals, there exists a significant challenge for radar emitter signal recognition. To address this challenge, multi-component radar emitter recognition under a complicated noise environment is studied in this paper. A novel radar emitter recognition approach based on the three-dimensional distribution feature and transfer learning is proposed. The cubic feature for the time-frequency-energy distribution is proposed to describe the intra-pulse modulation information of radar emitters. Furthermore, the feature is reconstructed by using transfer learning in order to obtain the robust feature against signal noise rate (SNR) variation. Last, but not the least, the relevance vector machine is used to classify radar emitter signals. Simulations demonstrate that the approach proposed in this paper has better performances in accuracy and robustness than existing approaches.

  5. Effect of electron beam cooling on transversal and longitudinal emittance of an external proton beam

    NASA Astrophysics Data System (ADS)

    Kilian, K.; Machner, H.; Magiera, A.; Prasuhn, D.; von Rossen, P.; Siudak, R.; Stein, H. J.; Stockhorst, H.

    2018-02-01

    Benefits of electron cooling to the quality of extracted ion beams from storage rings are discussed. The transversal emittances of an external proton beam with and without electron cooling at injection energy are measured with the GEM detector assembly. While the horizontal emittance remains the vertical emittance shrinks by the cooling process. The longitudinal momentum variance is also reduced by cooling.

  6. Active spacecraft potential control: An ion emitter experiment. [Cluster mission

    NASA Technical Reports Server (NTRS)

    Riedler, W.; Goldstein, R.; Hamelin, M.; Maehlum, B. N.; Troim, J.; Olsen, R. C.; Pedersen, A.; Grard, R. J. L.; Schmidt, R.; Rudenauer, F.

    1988-01-01

    The cluster spacecraft are instrumented with ion emitters for charge neutralization. The emitters produce indium ions at 6 keV. The ion current is adjusted in a feedback loop with instruments measuring the spacecraft potential. The system is based on the evaporation of indium in the apex field of a needle. The design of the active spacecraft potential control instruments, and the ion emitters is presented.

  7. Organic light-emitting device with a phosphor-sensitized fluorescent emission layer

    DOEpatents

    Forrest, Stephen [Ann Arbor, MI; Kanno, Hiroshi [Osaka, JP

    2009-08-25

    The present invention relates to organic light emitting devices (OLEDs), and more specifically to OLEDS that emit light using a combination of fluorescent emitters and phosphorescent emitters. The emissive region of the devices of the present invention comprise at least one phosphor-sensitized layer which has a combined emission from a phosphorescent emitter and a fluorescent emitter. In preferred embodiments, the invention relates to white-emitting OLEDS (WOLEDs).

  8. Characterization of NiSi nanowires as field emitters and limitations of Fowler-Nordheim model at the nanoscale

    NASA Astrophysics Data System (ADS)

    Belkadi, Amina B.; Gale, E.; Isakovic, A. F.

    2015-03-01

    Nanoscale field emitters are of technological interest because of the anticipated faster turn-on time, better sustainability and compactness. This report focuses on NiSi nanowires as field emitters for two reasons: (a) possible enhancement of field emission in nanoscale field emitters over bulk, and (b) achieving the same field emission properties as in bulk, but at a lower energy cost. To this end, we have grown, fabricated and characterized NiSi nanowires as field emitters. Depending on the geometry of the NiSi nanowires (aspect ratio, shape etc.), the relevant major field emission parameters, such as (1) the turn-on field, (2) the work function, and (3) the field enhancement factor, can be comparable or even superior to other recently explored nanoscale field emitters, such as CdS and ZnO. We also report on a comparative performance of various nanoscale field emitters and on the difficulties in the performance comparison in the light of relatively poor applicability of the standard Folwer-Nordheim model for field emission analysis for the case of the nanoscale field emitters. Proposed modifications are discussed. This work is supported through SRC-ATIC Grant 2011-KJ-2190. We also acknoweldge BNL-CFN and Cornell CNF facilities and staff.

  9. Silicon solar cells made by a self-aligned, selective-emitter, plasma-etchback process

    DOEpatents

    Ruby, Douglas S.; Schubert, William K.; Gee, James M.

    1999-01-01

    A potentially low-cost process for forming and passivating a selective emitter. The process uses a plasma etch of the heavily doped emitter to improve its performance. The grids of the solar cell are used to mask the plasma etch so that only the emitter in the region between the grids is etched, while the region beneath the grids remains heavily doped for low contact resistance. This process is potentially low-cost because it requires no alignment. After the emitter etch, a silicon nitride layer is deposited by plasma-enhanced, chemical vapor deposition, and the solar cell is annealed in a forming gas.

  10. Silicon solar cells made by a self-aligned, selective-emitter, plasma-etchback process

    DOEpatents

    Ruby, D.S.; Schubert, W.K.; Gee, J.M.

    1999-02-16

    A potentially low-cost process for forming and passivating a selective emitter. The process uses a plasma etch of the heavily doped emitter to improve its performance. The grids of the solar cell are used to mask the plasma etch so that only the emitter in the region between the grids is etched, while the region beneath the grids remains heavily doped for low contact resistance. This process is potentially low-cost because it requires no alignment. After the emitter etch, a silicon nitride layer is deposited by plasma-enhanced, chemical vapor deposition, and the solar cell is annealed in a forming gas. 5 figs.

  11. Determination and error analysis of emittance and spectral emittance measurements by remote sensing

    NASA Technical Reports Server (NTRS)

    Dejesusparada, N. (Principal Investigator); Kumar, R.

    1977-01-01

    The author has identified the following significant results. From the theory of remote sensing of surface temperatures, an equation of the upper bound of absolute error of emittance was determined. It showed that the absolute error decreased with an increase in contact temperature, whereas, it increased with an increase in environmental integrated radiant flux density. Change in emittance had little effect on the absolute error. A plot of the difference between temperature and band radiance temperature vs. emittance was provided for the wavelength intervals: 4.5 to 5.5 microns, 8 to 13.5 microns, and 10.2 to 12.5 microns.

  12. Effect of low temperature oxidation (LTO) in reducing boron skin in boron spin on dopant diffused emitter

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Singha, Bandana; Solanki, Chetan Singh

    Formation of boron skin is an unavoidable phenomenon in p-type emitter formation with boron dopant source. The boron skin thickness is generally less than 100 nm and difficult to remove by chemical and physical means. Low temperature oxidation (LTO) used in this work is useful in removing boron skin thickness up to 30 nm and improves the emitter performance. The effective minority carrier lifetime gets improved by more than 30% after using LTO and leakage current of the emitter gets lowered by 100 times thereby showing the importance of low temperature oxidation in boron spin on dopant diffused emitters.

  13. Self aligning electron beam gun having enhanced thermal and mechanical stability

    DOEpatents

    Scarpetti, Jr., Raymond D.; Parkison, Clarence D.; Switzer, Vernon A.; Lee, Young J.; Sawyer, William C.

    1995-01-01

    A compact, high power electron gun having enhanced thermal and mechanical stability which incorporates a mechanically coupled, self aligning structure for the anode and cathode. The enhanced stability, and reduced need for realignment of the cathode to the anode and downstream optics during operation are achieved by use of a common support structure for the cathode and anode which requires no adjustment screws or spacers. The electron gun of the present invention also incorporates a modular design for the cathode, in which the electron emitter, its support structure, and the hardware required to attach the emitter assembly to the rest of the gun are a single element. This modular design makes replacement of the emitter simpler and requires no realignment after a new emitter has been installed. Compactness and a reduction in the possibility of high voltage breakdown are achieved by shielding the "triple point" where the electrode, insulator, and vacuum meet. The use of electric discharge machining (EDM) for fabricating the emitter allows for the accurate machining of the emitter into intricate shapes without encountering the normal stresses developed by standard emitter fabrication techniques.

  14. Nanostructured GaAs solar cells via metal-assisted chemical etching of emitter layers.

    PubMed

    Song, Yunwon; Choi, Keorock; Jun, Dong-Hwan; Oh, Jungwoo

    2017-10-02

    GaAs solar cells with nanostructured emitter layers were fabricated via metal-assisted chemical etching. Au nanoparticles produced via thermal treatment of Au thin films were used as etch catalysts to texture an emitter surface with nanohole structures. Epi-wafers with emitter layers 0.5, 1.0, and 1.5 um in thickness were directly textured and a window layer removal process was performed before metal catalyst deposition. A nanohole-textured emitter layer provides effective light trapping capabilities, reducing the surface reflection of a textured solar cell by 11.0%. However, because the nanostructures have high surface area to volume ratios and large numbers of defects, various photovoltaic properties were diminished by high recombination losses. Thus, we have studied the application of nanohole structures to GaAs emitter solar cells and investigated the cells' antireflection and photovoltaic properties as a function of the nanohole structure and emitter thickness. Due to decreased surface reflection and improved shunt resistance, the solar cell efficiency increased from 4.25% for non-textured solar cells to 7.15% for solar cells textured for 5 min.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Long-term, correlated emittance decrease in intense, high-brightness induction linacs

    NASA Astrophysics Data System (ADS)

    Carlsten, Bruce E.

    1999-09-01

    Simulations of high-brightness induction linacs often show a slow, long-term emittance decrease as the beam is matched from the electron gun into the linac. Superimposed on this long-term decrease are rapid emittance oscillations. These effects can be described in terms of correlations in the beam's radial phase space. The rapid emittance oscillations are due to transverse plasma oscillations, which stay nearly in phase for different radial positions within the beam. The initial emittance, just after the electron gun, is dominated by nonlinear focusing within the gun introduced by the anode exit hole. Due to the large space-charge force of an intense electron beam, the focusing of the beam through the matching section introduces an effective nonlinear force (from the change in the particles' potential energies) which counteracts the nonlinearities from the electron gun, leading to an average, long-term emittance decrease. Not all of the initial nonlinearity is removed by the matching procedure, and there are important consequences both for emittance measurements using solenoid focal length scans and for focusing the electron beam to a target.

  17. Further Studies on the Effect of SiN x Refractive Index and Emitter Sheet Resistance on Potential-Induced Degradation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Oh, Jaewon; Dauksher, Bill; Bowden, Stuart

    We present the impacts of silicon nitride (SiNx) antireflection coating refractive index and emitter sheet resistance on potential-induced degradation of the shunting type (PID-s). Previously, it has been shown that the cell becomes more PID-s-susceptible as the refractive index decreases or the emitter sheet resistance increases. To verify the effect of refractive index on PID-s, we fabricated cells with varying SiN x refractive index (1.87, 1.94, 2.05) on typical p-type base solar cells with ~60 Ω/sq emitters. However, none of these cells showed output power degradation, regardless of the refractive index. Further investigation of the emitter showed that the PID-smore » was suppressed at ~60 Ω/sq due to the extremely high surface phosphorus concentration (6 x 10 21 cm -3), as measured by secondary ion mass spectrometry. Furthermore, PID-s was observed on cells possessing a high emitter sheet resistance (~80 Ω/sq). In conclusion, the emitter surface phosphorus concentration plays an important role in determining PID-s susceptibility.« less

  18. Further Studies on the Effect of SiN x Refractive Index and Emitter Sheet Resistance on Potential-Induced Degradation

    DOE PAGES

    Oh, Jaewon; Dauksher, Bill; Bowden, Stuart; ...

    2017-01-11

    We present the impacts of silicon nitride (SiNx) antireflection coating refractive index and emitter sheet resistance on potential-induced degradation of the shunting type (PID-s). Previously, it has been shown that the cell becomes more PID-s-susceptible as the refractive index decreases or the emitter sheet resistance increases. To verify the effect of refractive index on PID-s, we fabricated cells with varying SiN x refractive index (1.87, 1.94, 2.05) on typical p-type base solar cells with ~60 Ω/sq emitters. However, none of these cells showed output power degradation, regardless of the refractive index. Further investigation of the emitter showed that the PID-smore » was suppressed at ~60 Ω/sq due to the extremely high surface phosphorus concentration (6 x 10 21 cm -3), as measured by secondary ion mass spectrometry. Furthermore, PID-s was observed on cells possessing a high emitter sheet resistance (~80 Ω/sq). In conclusion, the emitter surface phosphorus concentration plays an important role in determining PID-s susceptibility.« less

  19. Final 6D Muon Ionization Colling using Strong Focusing Quadrupoles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hart, T. L.; Acosta, J. G.; Cremaldi, L. M.

    2016-11-15

    Abstract Low emittance muon beam lines and muon colliders are potentially a rich source of BSM physics for future exper- imenters. A muon beam normalized emittance of ax,y,z = (280, 280, 1570)µm has been achieved in simulation with short solenoids and a betatron function of 3 cm. Here we use ICOOL and MAD-X to explore using a 400 MeV/c muon beam and strong focusing quadrupoles to achieve a normalized transverse emittance of 100 µm and complete 6D cooling. The low beta regions, as low as 5 mm, produced by the quadrupoles are occupied by dense, low Z absorbers, such asmore » lithium hydride or beryllium, that cool the beam transversely. Equilibrium transverse emittance is linearly proportional to the transverse betatron function. Reverse emittance exchange with septa and/or wedges is then used to decrease transverse emittance from 100 to 25 µm at the expense of longitudinal emittance for a high energy lepton collider. Cooling challenges include chromaticity correction, ssband overlap, quadrupole acceptance, and staying in phase with RF.« less

  20. Carbon and metal nanotube hybrid structures on graphene as efficient electron field emitters

    NASA Astrophysics Data System (ADS)

    Heo, Kwang; Lee, Byung Yang; Lee, Hyungwoo; Cho, Dong-guk; Arif, Muhammad; Kim, Kyu Young; Choi, Young Jin; Hong, Seunghun

    2016-07-01

    We report a facile and efficient method for the fabrication of highly-flexible field emission devices by forming tubular hybrid structures based on carbon nanotubes (CNTs) and nickel nanotubes (Ni NTs) on graphene-based flexible substrates. By employing an infiltration process in anodic alumina oxide (AAO) templates followed by Ni electrodeposition, we could fabricate CNT-wrapped Ni NT/graphene hybrid structures. During the electrodeposition process, the CNTs served as Ni nucleation sites, resulting in a large-area array of high aspect-ratio field emitters composed of CNT-wrapped Ni NT hybrid structures. As a proof of concepts, we demonstrate that high-quality flexible field emission devices can be simply fabricated using our method. Remarkably, our proto-type field emission devices exhibited a current density higher by two orders of magnitude compared to other devices fabricated by previous methods, while maintaining its structural integrity in various bending deformations. This novel fabrication strategy can be utilized in various applications such as optoelectronic devices, sensors and energy storage devices.

  1. Carbon and metal nanotube hybrid structures on graphene as efficient electron field emitters.

    PubMed

    Heo, Kwang; Lee, Byung Yang; Lee, Hyungwoo; Cho, Dong-Guk; Arif, Muhammad; Kim, Kyu Young; Choi, Young Jin; Hong, Seunghun

    2016-07-08

    We report a facile and efficient method for the fabrication of highly-flexible field emission devices by forming tubular hybrid structures based on carbon nanotubes (CNTs) and nickel nanotubes (Ni NTs) on graphene-based flexible substrates. By employing an infiltration process in anodic alumina oxide (AAO) templates followed by Ni electrodeposition, we could fabricate CNT-wrapped Ni NT/graphene hybrid structures. During the electrodeposition process, the CNTs served as Ni nucleation sites, resulting in a large-area array of high aspect-ratio field emitters composed of CNT-wrapped Ni NT hybrid structures. As a proof of concepts, we demonstrate that high-quality flexible field emission devices can be simply fabricated using our method. Remarkably, our proto-type field emission devices exhibited a current density higher by two orders of magnitude compared to other devices fabricated by previous methods, while maintaining its structural integrity in various bending deformations. This novel fabrication strategy can be utilized in various applications such as optoelectronic devices, sensors and energy storage devices.

  2. Measurement and evaluation of the radiative properties of a thin solid fuel

    NASA Technical Reports Server (NTRS)

    Pettegrew, Richard; Street, Kenneth; Pitch, Nancy; Tien, James; Morrison, Phillip

    2003-01-01

    Accurate modeling of combustion systems requires knowledge of the radiative properties of the system. Gas phase properties are well known, but detailed knowledge of surface properties is limited. Recent work has provided spectrally resolved data for some solid fuels, but only for the unburned material at room temperature, and for limited sets of previously burned and quenched samples. Due to lack of knowledge of the spectrally resolved properties at elevated temperatures, as well as processing limitations in the modeling effort, graybody values are typically used for the fuels surface radiative properties. However, the spectrally resolved properties for the fuels at room temperature can be used to give a first-order correction for temperature effects on the graybody values. Figure 1 shows a sample of the spectrally resolved emittance/absorptance for a thin solid fuel of the type commonly used in combustion studies, from approximately 2 to 20 microns. This plot clearly shows a strong spectral dependence across the entire range. By definition, the emittance is the ratio of the emitted energy to that of a blackbody at the same temperature. Therefore, to determine a graybody emittance for this material, the spectrally resolved data must be applied to a blackbody curve. The total area under the resulting curve is ratioed to the total area under the blackbody curve to yield the answer. Due to the asymmetry of the spectrally resolved emittance and the changing shape of the blackbody curve as the temperature increases, the relative importance of the emittance value at any given wavelength will change as a function of temperature. Therefore, the graybody emittance value for a given material will change as a function of temperature even if the spectral dependence of the radiative properties remains unchanged. This is demonstrated in Figures 2 and 3, which are plots of the spectrally resolved emittance for KimWipes (shown in Figure 1) multiplied by the blackbody curves for 300 K (Figure 2) and 800 K (Figure 3). Each figure also shows the blackbody curve for that temperature. Ratioing the areas under the curve for each of these figures give a graybody emittance of 0.64 at 300 K, and 0.46 at 800 K. It is recognized that materials undergoing pyrolysis will change in composition as they heat up, and that the radiative properties of the materials may have inherent temperature dependence. Both of these effects will contribute to changes in the radiative characteristics of a given material, and are not accounted for here. However, this paper demonstrates the temperature dependence of graybody radiative properties, and provides a method for a first-order correction (for temperature) to the graybody values if the spectrally resolved properties are known.

  3. Small slot waveguide rings for on-chip quantum optical circuits.

    PubMed

    Rotenberg, Nir; Türschmann, Pierre; Haakh, Harald R; Martin-Cano, Diego; Götzinger, Stephan; Sandoghdar, Vahid

    2017-03-06

    Nanophotonic interfaces between single emitters and light promise to enable new quantum optical technologies. Here, we use a combination of finite element simulations and analytic quantum theory to investigate the interaction of various quantum emitters with slot-waveguide rings. We predict that for rings with radii as small as 1.44 μm, with a Q-factor of 27,900, near-unity emitter-waveguide coupling efficiencies and emission enhancements on the order of 1300 can be achieved. By tuning the ring geometry or introducing losses, we show that realistic emitter-ring systems can be made to be either weakly or strongly coupled, so that we can observe Rabi oscillations in the decay dynamics even for micron-sized rings. Moreover, we demonstrate that slot waveguide rings can be used to directionally couple emission, again with near-unity efficiency. Our results pave the way for integrated solid-state quantum circuits involving various emitters.

  4. Selective Emitters

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L. (Inventor)

    1992-01-01

    This invention relates to a small particle selective emitter for converting thermal energy into narrow band radiation with high efficiency. The small particle selective emitter is used in combination with a photovoltaic array to provide a thermal to electrical energy conversion device. An energy conversion apparatus of this type is called a thermo-photovoltaic device. In the first embodiment, small diameter particles of a rare earth oxide are suspended in an inert gas enclosed between concentric cylinders. The rare earth oxides are used because they have the desired property of large emittance in a narrow wavelength band and small emittance outside the band. However, it should be emphasized that it is the smallness of the particles that enhances the radiation property. The small particle selective emitter is surrounded by a photovoltaic array. In an alternate embodiment, the small particle gas mixture is circulated through a thermal energy source. This thermal energy source can be a nuclear reactor, solar receiver, or combustor of a fossil fuel.

  5. Secondary emission electron gun using external primaries

    DOEpatents

    Srinivasan-Rao, Triveni [Shoreham, NY; Ben-Zvi, Ilan [Setauket, NY

    2009-10-13

    An electron gun for generating an electron beam is provided, which includes a secondary emitter. The secondary emitter includes a non-contaminating negative-electron-affinity (NEA) material and emitting surface. The gun includes an accelerating region which accelerates the secondaries from the emitting surface. The secondaries are emitted in response to a primary beam generated external to the accelerating region. The accelerating region may include a superconducting radio frequency (RF) cavity, and the gun may be operated in a continuous wave (CW) mode. The secondary emitter includes hydrogenated diamond. A uniform electrically conductive layer is superposed on the emitter to replenish the extracted current, preventing charging of the emitter. An encapsulated secondary emission enhanced cathode device, useful in a superconducting RF cavity, includes a housing for maintaining vacuum, a cathode, e.g., a photocathode, and the non-contaminating NEA secondary emitter with the uniform electrically conductive layer superposed thereon.

  6. Secondary emission electron gun using external primaries

    DOEpatents

    Srinivasan-Rao, Triveni [Shoreham, NY; Ben-Zvi, Ilan [Setauket, NY; Kewisch, Jorg [Wading River, NY; Chang, Xiangyun [Middle Island, NY

    2007-06-05

    An electron gun for generating an electron beam is provided, which includes a secondary emitter. The secondary emitter includes a non-contaminating negative-electron-affinity (NEA) material and emitting surface. The gun includes an accelerating region which accelerates the secondaries from the emitting surface. The secondaries are emitted in response to a primary beam generated external to the accelerating region. The accelerating region may include a superconducting radio frequency (RF) cavity, and the gun may be operated in a continuous wave (CW) mode. The secondary emitter includes hydrogenated diamond. A uniform electrically conductive layer is superposed on the emitter to replenish the extracted current, preventing charging of the emitter. An encapsulated secondary emission enhanced cathode device, useful in a superconducting RF cavity, includes a housing for maintaining vacuum, a cathode, e.g., a photocathode, and the non-contaminating NEA secondary emitter with the uniform electrically conductive layer superposed thereon.

  7. Evaluations of carbon nanotube field emitters for electron microscopy

    NASA Astrophysics Data System (ADS)

    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.

  8. Deterministic strain-induced arrays of quantum emitters in a two-dimensional semiconductor

    PubMed Central

    Branny, Artur; Kumar, Santosh; Proux, Raphaël; Gerardot, Brian D

    2017-01-01

    An outstanding challenge in quantum photonics is scalability, which requires positioning of single quantum emitters in a deterministic fashion. Site positioning progress has been made in established platforms including defects in diamond and self-assembled quantum dots, albeit often with compromised coherence and optical quality. The emergence of single quantum emitters in layered transition metal dichalcogenide semiconductors offers new opportunities to construct a scalable quantum architecture. Here, using nanoscale strain engineering, we deterministically achieve a two-dimensional lattice of quantum emitters in an atomically thin semiconductor. We create point-like strain perturbations in mono- and bi-layer WSe2 which locally modify the band-gap, leading to efficient funnelling of excitons towards isolated strain-tuned quantum emitters that exhibit high-purity single photon emission. We achieve near unity emitter creation probability and a mean positioning accuracy of 120±32 nm, which may be improved with further optimization of the nanopillar dimensions. PMID:28530219

  9. Comparison of Tungsten and Molybdenum Based Emitters for Advanced Thermionic Space Nuclear Reactors

    NASA Astrophysics Data System (ADS)

    Lee, Hsing H.; Dickinson, Jeffrey W.; Klein, Andrew C.; Lamp, Thomas R.

    1994-07-01

    Variations to the Advanced Thermionic Initiative thermionic fuel element are analyzed. Analysis included neutronic modeling with MCNP for criticality determination and thermal power distribution, and thermionic performance modeling with TFEHX. Changes to the original ATI configuration include the addition of W-HfC wire to the emitter for high temperature creep resistance improvement and substitution of molybdenum for the tungsten base material. Results from MCNP showed that all the tungsten used in the coating and base material must be 100% W-184 to obtain criticality. The presence of molybdenum in the emitter base affects the neutronic performance of the TFE by increasing the emitter neutron absorption cross section. Due to the reduced thermal conductivity for the molybdenum based emitter, a higher temperature is obtained resulting in a greater electrical power production. The thermal conductivity and resistivity of the composite emitter region were derived for the W-Mo composite and used in TFEHX.

  10. Correlation between positron emission tomography and Cerenkov luminescence imaging in vivo and ex vivo using 64Cu-labeled antibodies in a neuroblastoma mouse model.

    PubMed

    Maier, Florian C; Schmitt, Julia; Maurer, Andreas; Ehrlichmann, Walter; Reischl, Gerald; Nikolaou, Konstantin; Handgretinger, Rupert; Pichler, Bernd J; Thaiss, Wolfgang M

    2016-10-11

    Antibody-based therapies gain momentum in clinical therapy, thus the need for accurate imaging modalities with respect to target identification and therapy monitoring are of increasing relevance. Cerenkov luminescence imaging (CLI) are a novel method detecting charged particles emitted during radioactive decay with optical imaging. Here, we compare Position Emission Tomography (PET) with CLI in a multimodal imaging study aiming at the fast and efficient screening of monoclonal antibodies (mAb) designated for targeting of the neuroblastoma-characteristic epitope disialoganglioside GD2. Neuroblastoma-bearing SHO mice were injected with a 64Cu-labeled GD2-specific mAb. The tumor uptake was imaged 3 h, 24 h and 48 h after tracer injection with both, PET and CLI, and was compared to the accumulation in GD2-negative control tumors (human embryonic kidney, HEK-293). In addition to an in vivo PET/CLI-correlation over time, we also demonstrate linear correlations of CLI- and γ-counter-based biodistribution analysis. CLI with its comparably short acquisition time can thus be used as an attractive one-stop-shop modality for the longitudinal monitoring of antibody-based tumor targeting and ex vivo biodistribution.These findings suggest CLI as a reliable alternative for PET and biodistribution studies with respect to fast and high-throughput screenings in subcutaneous tumors traced with radiolabeled antibodies. However, in contrast to PET, CLI is not limited to positron-emitting isotopes and can therefore also be used for the visualization of mAb labeled with therapeutic isotopes like electron emitters.

  11. Space charge effects on the current-voltage characteristics of gated field emitter arrays

    NASA Astrophysics Data System (ADS)

    Jensen, K. L.; Kodis, M. A.; Murphy, R. A.; Zaidman, E. G.

    1997-07-01

    Microfabricated field emitter arrays (FEAs) can provide the very high electron current densities required for rf amplifier applications, typically on the order of 100 A/cm2. Determining the dependence of emission current on gate voltage is important for the prediction of emitter performance for device applications. Field emitters use high applied fields to extract current, and therefore, unlike thermionic emitters, the current densities can exceed 103A/cm2 when averaged over an array. At such high current densities, space charge effects (i.e., the influence of charge between cathode and collector on emission) affect the emission process or initiate conditions which can lead to failure mechanisms for field emitters. A simple model of a field emitter will be used to calculate the one-dimensional space charge effects on the emission characteristics by examining two components: charge between the gate and anode, which leads to Child's law, and charge within the FEA unit cell, which gives rise to a field suppression effect which can exist for a single field emitter. The predictions of the analytical model are compared with recent experimental measurements designed to assess space charge effects and predict the onset of gate current. It is shown that negative convexity on a Fowler-Nordheim plot of Ianode(Vgate) data can be explained in terms of field depression at the emitter tip in addition to reflection of electrons by a virtual cathode created when the anode field is insufficient to extract all of the current; in particular, the effects present within the unit cell constitute a newly described effect.

  12. The host dark matter haloes of [O II] emitters at 0.5 < z < 1.5

    NASA Astrophysics Data System (ADS)

    Gonzalez-Perez, V.; Comparat, J.; Norberg, P.; Baugh, C. M.; Contreras, S.; Lacey, C.; McCullagh, N.; Orsi, A.; Helly, J.; Humphries, J.

    2018-03-01

    Emission line galaxies (ELGs) are used in several ongoing and upcoming surveys (SDSS-IV/eBOSS, DESI) as tracers of the dark matter distribution. Using a new galaxy formation model, we explore the characteristics of [O II] emitters, which dominate optical ELG selections at z ≃ 1. Model [O II] emitters at 0.5 < z < 1.5 are selected to mimic the DEEP2, VVDS, eBOSS and DESI surveys. The luminosity functions of model [O II] emitters are in reasonable agreement with observations. The selected [O II] emitters are hosted by haloes with Mhalo ≥ 1010.3h-1M⊙, with ˜90 per cent of them being central star-forming galaxies. The predicted mean halo occupation distributions of [O II] emitters have a shape typical of that inferred for star-forming galaxies, with the contribution from central galaxies, < N > _{[O II] cen}, being far from the canonical step function. The < N > _{[O II] cen}} can be described as the sum of an asymmetric Gaussian for discs and a step function for spheroids, which plateau below unity. The model [O II] emitters have a clustering bias close to unity, which is below the expectations for eBOSS and DESI ELGs. At z ˜ 1, a comparison with observed g-band-selected galaxy, which is expected to be dominated by [O II] emitters, indicates that our model produces too few [O II] emitters that are satellite galaxies. This suggests the need to revise our modelling of hot gas stripping in satellite galaxies.

  13. Neutron responsive self-powered radiation detector

    DOEpatents

    Brown, Donald P.; Cannon, Collins P.

    1978-01-01

    An improved neutron responsive self-powered radiation detector is disclosed in which the neutron absorptive central emitter has a substantially neutron transmissive conductor collector sheath spaced about the emitter and the space between the emitter and collector sheath is evacuated.

  14. Two-nucleon emitters within a pseudostate method: The case of 6Be and 16Be

    NASA Astrophysics Data System (ADS)

    Casal, J.

    2018-03-01

    Background: Since the first experimental observation, two-nucleon radioactivity has gained renewed attention since the early 2000s. The 6Be system is the lightest two-proton ground-state emitter, while 16Be was recently proposed to be the first two-neutron ground-state emitter ever observed. A proper understanding of their properties and decay modes requires a reasonable description of the three-body continuum. Purpose: Study the ground-state properties of 6Be and 16Be within a general three-body model and investigate their nucleon-nucleon correlations in the continuum. Method: The pseudostate (PS) method in hyperspherical coordinates, using the analytical transformed harmonic oscillator (THO) basis for three-body systems, is used to construct the 6Be and 16Be ground-state wave functions. These resonances are approximated as a stable PS around the known two-nucleon separation energy. Effective core-N potentials, constrained by the available experimental information on the binary subsystems 5Li and 15Be, are employed in the calculations. Results: The ground state of 16Be is found to present a strong dineutron configuration, with the valence neutrons occupying mostly an l =2 state relative to the core. The results are consistent with previous R -matrix calculations for the actual continuum. The case of 6Be shows a clear symmetry with respect to its mirror partner, the two-neutron halo 6He: The diproton configuration is dominant, and the valence protons occupy an l =1 orbit. Conclusions: The PS method is found to be a suitable tool in describing the properties of unbound core+N +N ground states. For both 16Be and 6Be, the results are consistent with previous theoretical studies and confirm the dominant dinucleon configuration. This favors the picture of a correlated two-nucleon emission.

  15. Beam commissioning of a superconducting rotating-gantry for carbon-ion radiotherapy

    NASA Astrophysics Data System (ADS)

    Iwata, Y.; Fujimoto, T.; Matsuba, S.; Fujita, T.; Sato, S.; Furukawa, T.; Hara, Y.; Mizushima, K.; Saraya, Y.; Tansho, R.; Saotome, N.; Shirai, T.; Noda, K.

    2016-10-01

    A superconducting rotating-gantry for carbon-ion radiotherapy was developed. This isocentric gantry can transport carbon ions having kinetic energies of between E=430 and 48 MeV/u to an isocenter over an angle of ±180°, and is further capable of performing three-dimensional raster-scanning irradiation. Construction of the entire rotating-gantry system was completed by the end of September 2015. Prior to beam commissioning, phase-space distributions of extracted carbon beams from the synchrotron were deduced by using an empirical method. In this method, phase-space distributions at the extraction channel of the synchrotron were modeled with 8 parameters, and the best parameters were determined so as to minimize a difference between the calculated and measured beam profiles by using a simplex method. Based on the phase-space distributions, beam optics through the beam-transport lines as well as the rotating gantry were designed. Since horizontal and vertical beam emittances, as extracted slowly from the synchrotron, generally differ with each other, a horizontal-vertical beam coupling would occur when the gantry rotates. Thus, the size and shape of beam spots at the isocenter should vary depending on the gantry angle. To compensate for the difference in the emittances, we employed a method to utilize multiple Coulomb scattering of the beam particles by a thin scatterer. Having compensated for the emittances and designed beam optics through the rotating gantry, beam commissioning over various combinations of gantry angles and beam energies was performed. By finely tuning the superconducting quadrupoles of the rotating gantry, we could successfully obtain the designed beam quality, which satisfies the requirements of scanning irradiation.

  16. Nondestructive examination using neutron activated positron annihilation

    DOEpatents

    Akers, Douglas W.; Denison, Arthur B.

    2001-01-01

    A method is provided for performing nondestructive examination of a metal specimen using neutron activated positron annihilation wherein the positron emitter source is formed within the metal specimen. The method permits in situ nondestructive examination and has the advantage of being capable of performing bulk analysis to determine embrittlement, fatigue and dislocation within a metal specimen.

  17. Redefining relative biological effectiveness in the context of the EQDX formalism: implications for alpha-particle emitter therapy.

    PubMed

    Hobbs, Robert F; Howell, Roger W; Song, Hong; Baechler, Sébastien; Sgouros, George

    2014-01-01

    Alpha-particle radiopharmaceutical therapy (αRPT) is currently enjoying increasing attention as a viable alternative to chemotherapy for targeting of disseminated micrometastatic disease. In theory, αRPT can be personalized through pre-therapeutic imaging and dosimetry. However, in practice, given the particularities of α-particle emissions, a dosimetric methodology that accurately predicts the thresholds for organ toxicity has not been reported. This is in part due to the fact that the biological effects caused by α-particle radiation differ markedly from the effects caused by traditional external beam (photon or electron) radiation or β-particle emitting radiopharmaceuticals. The concept of relative biological effectiveness (RBE) is used to quantify the ratio of absorbed doses required to achieve a given biological response with alpha particles versus a reference radiation (typically a beta emitter or external beam radiation). However, as conventionally defined, the RBE varies as a function of absorbed dose and therefore a single RBE value is limited in its utility because it cannot be used to predict response over a wide range of absorbed doses. Therefore, efforts are underway to standardize bioeffect modeling for different fractionation schemes and dose rates for both nuclear medicine and external beam radiotherapy. Given the preponderant use of external beams of radiation compared to nuclear medicine in cancer therapy, the more clinically relevant quantity, the 2 Gy equieffective dose, EQD2(α/β), has recently been proposed by the ICRU. In concert with EQD2(α/β), we introduce a new, redefined RBE quantity, named RBE2(α/β), as the ratio of the two linear coefficients that characterize the α particle absorbed dose-response curve and the low-LET megavoltage photon 2 Gy fraction equieffective dose-response curve. The theoretical framework for the proposed new formalism is presented along with its application to experimental data obtained from irradiation of a breast cancer cell line. Radiobiological parameters are obtained using the linear quadratic model to fit cell survival data for MDA-MB-231 human breast cancer cells that were irradiated with either α particles or a single fraction of low-LET (137)Cs γ rays. From these, the linear coefficient for both the biologically effective dose (BED) and the EQD2(α/β) response lines were derived for fractionated irradiation. The standard RBE calculation, using the traditional single fraction reference radiation, gave RBE values that ranged from 2.4 for a surviving fraction of 0.82-6.0 for a surviving fraction of 0.02, while the dose-independent RBE2(4.6) value was 4.5 for all surviving fraction values. Furthermore, bioeffect modeling with RBE2(α/β) and EQD2(α/β) demonstrated the capacity to predict the surviving fraction of cells irradiated with acute and fractionated low-LET radiation, α particles and chronic exponentially decreasing dose rates of low-LET radiation. RBE2(α/β) is independent of absorbed dose for α-particle emitters and it provides a more logical framework for data reporting and conversion to equieffective dose than the conventional dose-dependent definition of RBE. Moreover, it provides a much needed foundation for the ongoing development of an α-particle dosimetry paradigm and will facilitate the use of tolerance dose data available from external beam radiation therapy, thereby helping to develop αRPT as a single modality as well as for combination therapies.

  18. Redefining Relative Biological Effectiveness in the Context of the EQDX Formalism: Implications for Alpha-Particle Emitter Therapy.

    PubMed

    Hobbs, Robert F; Howell, Roger W; Song, Hong; Baechler, Sébastien; Sgouros, George

    2013-12-30

    Alpha-particle radiopharmaceutical therapy (αRPT) is currently enjoying increasing attention as a viable alternative to chemotherapy for targeting of disseminated micrometastatic disease. In theory, αRPT can be personalized through pre-therapeutic imaging and dosimetry. However, in practice, given the particularities of α-particle emissions, a dosimetric methodology that accurately predicts the thresholds for organ toxicity has not been reported. This is in part due to the fact that the biological effects caused by α-particle radiation differ markedly from the effects caused by traditional external beam (photon or electron) radiation or β-particle emitting radiopharmaceuticals. The concept of relative biological effectiveness (RBE) is used to quantify the ratio of absorbed doses required to achieve a given biological response with alpha particles versus a reference radiation (typically a beta emitter or external beam radiation). However, as conventionally defined, the RBE varies as a function of absorbed dose and therefore a single RBE value is limited in its utility because it cannot be used to predict response over a wide range of absorbed doses. Therefore, efforts are underway to standardize bioeffect modeling for different fractionation schemes and dose rates for both nuclear medicine and external beam radiotherapy. Given the preponderant use of external beams of radiation compared to nuclear medicine in cancer therapy, the more clinically relevant quantity, the 2 Gy equieffective dose, EQD2(α/β), has recently been proposed by the ICRU. In concert with EQD2(α/β), we introduce a new, redefined RBE quantity, named RBE2(α/β), as the ratio of the two linear coefficients that characterize the α particle absorbed dose-response curve and the low-LET megavoltage photon 2 Gy fraction equieffective dose-response curve. The theoretical framework for the proposed new formalism is presented along with its application to experimental data obtained from irradiation of a breast cancer cell line. Radiobiological parameters are obtained using the linear quadratic model to fit cell survival data for MDA-MB-231 human breast cancer cells that were irradiated with either α particles or a single fraction of low-LET 137 Cs γ rays. From these, the linear coefficient for both the biologically effective dose (BED) and the EQD2(α/β) response lines were derived for fractionated irradiation. The standard RBE calculation, using the traditional single fraction reference radiation, gave RBE values that ranged from 2.4 for a surviving fraction of 0.82-6.0 for a surviving fraction of 0.02, while the dose-independent RBE2(4.6) value was 4.5 for all surviving fraction values. Furthermore, bioeffect modeling with RBE2(α/β) and EQD2(α/β) demonstrated the capacity to predict the surviving fraction of cells irradiated with acute and fractionated low-LET radiation, α particles and chronic exponentially decreasing dose rates of low-LET radiation. RBE2(α/β) is independent of absorbed dose for α-particle emitters and it provides a more logical framework for data reporting and conversion to equieffective dose than the conventional dose-dependent definition of RBE. Moreover, it provides a much needed foundation for the ongoing development of an α-particle dosimetry paradigm and will facilitate the use of tolerance dose data available from external beam radiation therapy, thereby helping to develop αRPT as a single modality as well as for combination therapies.

  19. Near-infrared roll-off-free electroluminescence from highly stable diketopyrrolopyrrole light emitting diodes

    PubMed Central

    Sassi, Mauro; Buccheri, Nunzio; Rooney, Myles; Botta, Chiara; Bruni, Francesco; Giovanella, Umberto; Brovelli, Sergio; Beverina, Luca

    2016-01-01

    Organic light emitting diodes (OLEDs) operating in the near-infrared spectral region are gaining growing relevance for emerging photonic technologies, such as lab-on-chip platforms for medical diagnostics, flexible self-medicated pads for photodynamic therapy, night vision and plastic-based telecommunications. The achievement of efficient near-infrared electroluminescence from solution-processed OLEDs is, however, an open challenge due to the low photoluminescence efficiency of most narrow-energy-gap organic emitters. Diketopyrrolopyrrole-boron complexes are promising candidates to overcome this limitation as they feature extremely high photoluminescence quantum yield in the near-infrared region and high chemical stability. Here, by incorporating suitably functionalized diketopyrrolopyrrole derivatives emitting at ~760 nm in an active matrix of poly(9,9-dioctylfluorene-alt-benzothiadiazole) and without using complex light out-coupling or encapsulation strategies, we obtain all-solution-processed NIR-OLEDs with external quantum efficiency as high as 0.5%. Importantly, our test-bed devices show no efficiency roll-off even for high current densities and high operational stability, retaining over 50% of the initial radiant emittance for over 50 hours of continuous operation at 10 mA/cm2, which emphasizes the great applicative potential of the proposed strategy. PMID:27677240

  20. Review of Gallium-68 PSMA PET/CT Imaging in the Management of Prostate Cancer

    PubMed Central

    Lenzo, Nat P.; Meyrick, Danielle; Turner, J. Harvey

    2018-01-01

    Over 90% of prostate cancers over-express prostate specific membrane antigen (PSMA) and these tumor cells may be accurately targeted for diagnosis by 68Ga-PSMA-positron emission tomography/computed tomography (68Ga-PSMA-PET/CT) imaging. This novel molecular imaging modality appears clinically to have superseded CT, and appears superior to MR imaging, for the detection of metastatic disease. 68Ga-PSMA PET/CT has the ability to reliably stage prostate cancer at presentation and can help inform an optimal treatment approach. Novel diagnostic applications of 68Ga-PSMA PET/CT include guiding biopsy to improve sampling accuracy, and guiding surgery and radiotherapy. In addition to facilitating the management of metastatic castrate resistant prostate cancer (mCRPC), 68Ga-PSMA can select patients who may benefit from targeted systemic radionuclide therapy. 68Ga-PSMA is the diagnostic positron-emitting theranostic pair with the beta emitter Lutetium-177 PSMA (177Lu-PSMA) and alpha-emitter Actinium-225 PSMA (225Ac-PSMA) which can both be used to treat PSMA-avid metastases of prostate cancer in the molecular tumor-targeted approach of theranostic nuclear oncology. PMID:29439481

  1. Determination of lifetimes and recombination currents in p-n junction solar cells, diodes, and transistors

    NASA Technical Reports Server (NTRS)

    Neugroschel, A.

    1981-01-01

    New methods are presented and illustrated that enable the accurate determination of the diffusion length of minority carriers in the narrow regions of a solar cell or a diode. Other methods now available are inaccurate for the desired case in which the width of the region is less than the diffusion length. Once the diffusion length is determined by the new methods, this result can be combined with measured dark I-V characteristics and with small-signal admittance characteristics to enable determination of the recombination currents in each quasi-neutral region of the cell - for example, in the emitter, low-doped base, and high-doped base regions of the BSF (back-surface-field) cell. This approach leads to values for the effective surface recombination velocity of the high-low junction forming the back-surface field of BSF cells or the high-low emitter junction of HLE cells. These methods are also applicable for measuring the minority-carrier lifetime in thin epitaxial layers grown on substrates with opposite conductivity type.

  2. Radar signal categorization using a neural network

    NASA Technical Reports Server (NTRS)

    Anderson, James A.; Gately, Michael T.; Penz, P. Andrew; Collins, Dean R.

    1991-01-01

    Neural networks were used to analyze a complex simulated radar environment which contains noisy radar pulses generated by many different emitters. The neural network used is an energy minimizing network (the BSB model) which forms energy minima - attractors in the network dynamical system - based on learned input data. The system first determines how many emitters are present (the deinterleaving problem). Pulses from individual simulated emitters give rise to separate stable attractors in the network. Once individual emitters are characterized, it is possible to make tentative identifications of them based on their observed parameters. As a test of this idea, a neural network was used to form a small data base that potentially could make emitter identifications.

  3. Emittance measurements in low energy ion storage rings

    NASA Astrophysics Data System (ADS)

    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.

  4. STABILIZED TRANSISTOR AMPLIFIER

    DOEpatents

    Noe, J.B.

    1963-05-01

    A temperature stabilized transistor amplifier having a pair of transistors coupled in cascade relation that are capable of providing amplification through a temperature range of - 100 un. Concent 85% F to 400 un. Concent 85% F described. The stabilization of the amplifier is attained by coupling a feedback signal taken from the emitter of second transistor at a junction between two serially arranged biasing resistances in the circuit of the emitter of the second transistor to the base of the first transistor. Thus, a change in the emitter current of the second transistor is automatically corrected by the feedback adjustment of the base-emitter potential of the first transistor and by a corresponding change in the base-emitter potential of the second transistor. (AEC)

  5. Dual-detection confocal fluorescence microscopy: fluorescence axial imaging without axial scanning.

    PubMed

    Lee, Dong-Ryoung; Kim, Young-Duk; Gweon, Dae-Gab; Yoo, Hongki

    2013-07-29

    We propose a new method for high-speed, three-dimensional (3-D) fluorescence imaging, which we refer to as dual-detection confocal fluorescence microscopy (DDCFM). In contrast to conventional beam-scanning confocal fluorescence microscopy, where the focal spot must be scanned either optically or mechanically over a sample volume to reconstruct a 3-D image, DDCFM can obtain the depth of a fluorescent emitter without depth scanning. DDCFM comprises two photodetectors, each with a pinhole of different size, in the confocal detection system. Axial information on fluorescent emitters can be measured by the axial response curve through the ratio of intensity signals. DDCFM can rapidly acquire a 3-D fluorescent image from a single two-dimensional scan with less phototoxicity and photobleaching than confocal fluorescence microscopy because no mechanical depth scans are needed. We demonstrated the feasibility of the proposed method by phantom studies.

  6. Graphene surface plasmons mediated thermal radiation

    NASA Astrophysics Data System (ADS)

    Li, Jiayu; Liu, Baoan; Shen, Sheng

    2018-02-01

    A graphene nanostructure can simultaneously serve as a plasmonic optical resonator and a thermal emitter when thermally heated up. The unique electronic and optical properties of graphene have rendered tremendous potential in the active manipulation of light and the microscopic energy transport in nanostructures. Here we show that the thermally pumped surface plasmonic modes along graphene nanoribbons could dramatically modulate their thermal emission spectra in both near- and far-fields. Based on the fluctuating surface current method implemented by the resistive boundary method, we directly calculate the thermal emission spectrum from single graphene ribbons and vertically paired graphene ribbons. Furthermore, we demonstrate that both the near- and far-field thermal emission from graphene nanostructures can be optimized by tuning the chemical potential of doped graphene. The general guideline to maximize the thermal emission is illustrated by the our recently developed theory on resonant thermal emitters modulated by quasi-normal modes.

  7. High speed infrared radiation thermometer, system, and method

    DOEpatents

    Markham, James R.

    2002-01-01

    The high-speed radiation thermometer has an infrared measurement wavelength band that is matched to the infrared wavelength band of near-blackbody emittance of ceramic components and ceramic thermal barrier coatings used in turbine engines. It is comprised of a long wavelength infrared detector, a signal amplifier, an analog-to-digital converter, an optical system to collect radiation from the target, an optical filter, and an integral reference signal to maintain a calibrated response. A megahertz range electronic data acquisition system is connected to the radiation detector to operate on raw data obtained. Because the thermometer operates optimally at 8 to 12 .mu.m, where emittance is near-blackbody for ceramics, interferences to measurements performed in turbine engines are minimized. The method and apparatus are optimized to enable mapping of surface temperatures on fast moving ceramic elements, and the thermometer can provide microsecond response, with inherent self-diagnostic and calibration-correction features.

  8. Experimental Approach to Evaluate the 11C Perfusion and Diffusion in Small Animal Tissues for HadronPET Applications.

    PubMed

    Martínez-Rovira, Immaculada; Boisgard, Raphaël; Pottier, Géraldine; Kuhnast, Bertrand; Jan, Sébastien

    2016-01-01

    The development of a reliable dose monitoring system in hadron therapy is essential in order to control the treatment plan delivery. Positron Emission Tomography (PET) is the only method used in clinics nowadays for quality assurance. However, the accuracy of this method is limited by the loss of signal due to the biological washout processes. Up to the moment, very few studies measured the washout processes and there is no database of washout data as a function of the tissue and radioisotope. One of the main difficulties is related to the complexity of such measurements, along with the limited time slots available in hadron therapy facilities. Thus, in this work, we proposed an alternative in vivo methodology for the measurement and modeling of the biological washout parameters without any radiative devices. It consists in the implementation of a point-like radioisotope source by direct injection on the tissues of interest and its measurement by means of high-resolution preclinical PET systems. In particular, the washout of 11C carbonate radioisotopes was assessed, considering that 11C is is the most abundant β+ emitter produced by carbon beams. 11C washout measurements were performed in several tissues of interest (brain, muscle and 9L tumor xenograf) in rodents (Wistar rat). Results show that the methodology presented is sensitive to the washout variations depending on the selected tissue. Finally, a first qualitative correlation between 11C tumor washout properties and tumor metabolism (via 18F-FDG tracer uptake) was found.

  9. The wave-field from an array of periodic emitters driven simultaneously by a broadband pulse.

    PubMed

    Dixon, Steve; Hill, Samuel; Fan, Yichao; Rowlands, George

    2013-06-01

    The use of phased array methods are commonplace in ultrasonic applications, where controlling the variation of the phase between the narrowband emitters in an array facilitates beam steering and focusing of ultrasonic waves. An approach is presented here whereby emitters of alternating polarity arranged in a one-dimensional array are pulsed simultaneously, and have sufficiently wide, controlled bandwidth to emit a two-dimensional wave. This pulsed approach provides a rapid means of simultaneously covering a region of space with a wave-front, whereby any wave that scatters or reflects off a body to a detector will have a distinct arrival time and frequency. This is a general wave phenomenon with a potential application in radar, sonar, and ultrasound. The key result is that one can obtain a smooth, continuous wave-front emitted from the array, over a large solid angle, whose frequency varies as a function of angle to the array. Analytic and finite element models created to describe this phenomenon have been validated with experimental results using ultrasonic waves in metal samples.

  10. "Sizing" the oligomers of Azami Green fluorescent protein with FCS and antibunching

    NASA Astrophysics Data System (ADS)

    Temirov, Jamshid; Werner, James H.; Goodwin, Peter M.; Bradbury, Andrew R. M.

    2012-02-01

    Fluorescent proteins are invaluable molecules in fluorescence microscopy and spectroscopy. The size and brightness of fluorescent proteins often dictates the application they may be used for. While a monomeric protein may be the least perturbative structure for labeling a protein in a cell, often oligomers (dimers and tetramers) of fluorescent proteins can be more stable. However, from a quantitative microscopy standpoint, it is important to realize the photophysical properties of monomers do not necessarily multiply by their number when they form oligomers. In this work we studied oligomerization states of the Azami Green (AG) protein with fluorescence correlation spectroscopy (FCS) and photon antibunching or photon pair correlation spectroscopy (PPCS). FCS was used to measure the hydrodynamic size of the oligomers, whereas antibunching was used to count the number of fluorescent emitters in the oligomers. The results exhibited that the dimers of AG were single emitters and the tetramers were dual-emitters, indicative of dipole-dipole interactions and energy transfer between the monomeric units. We also used these methods to estimate the number of fluorescent proteins displayed on T7 phage molecules.

  11. Photon scattering from a system of multilevel quantum emitters. II. Application to emitters coupled to a one-dimensional waveguide

    NASA Astrophysics Data System (ADS)

    Das, Sumanta; Elfving, Vincent E.; Reiter, Florentin; Sørensen, Anders S.

    2018-04-01

    In a preceding paper we introduced a formalism to study the scattering of low-intensity fields from a system of multilevel emitters embedded in a three-dimensional (3 D ) dielectric medium. Here we show how this photon-scattering relation can be used to analyze the scattering of single photons and weak coherent states from any generic multilevel quantum emitter coupled to a one-dimensional (1 D ) waveguide. The reduction of the photon-scattering relation to 1 D waveguides provides a direct solution of the scattering problem involving low-intensity fields in the waveguide QED regime. To show how our formalism works, we consider examples of multilevel emitters and evaluate the transmitted and reflected field amplitude. Furthermore, we extend our study to include the dynamical response of the emitters for scattering of a weak coherent photon pulse. As our photon-scattering relation is based on the Heisenberg picture, it is quite useful for problems involving photodetection in the waveguide architecture. We show this by considering a specific problem of state generation by photodetection in a multilevel emitter, where our formalism exhibits its full potential. Since the considered emitters are generic, the 1 D results apply to a plethora of physical systems such as atoms, ions, quantum dots, superconducting qubits, and nitrogen-vacancy centers coupled to a 1 D waveguide or transmission line.

  12. ALMA deep field in SSA22: Blindly detected CO emitters and [C II] emitter candidates

    NASA Astrophysics Data System (ADS)

    Hayatsu, Natsuki H.; Matsuda, Yuichi; Umehata, Hideki; Yoshida, Naoki; Smail, Ian; Swinbank, A. Mark; Ivison, Rob; Kohno, Kotaro; Tamura, Yoichi; Kubo, Mariko; Iono, Daisuke; Hatsukade, Bunyo; Nakanishi, Kouichiro; Kawabe, Ryohei; Nagao, Tohru; Inoue, Akio K.; Takeuchi, Tsutomu T.; Lee, Minju; Ao, Yiping; Fujimoto, Seiji; Izumi, Takuma; Yamaguchi, Yuki; Ikarashi, Soh; Yamada, Toru

    2017-06-01

    We report the identification of four millimeter line-emitting galaxies with the Atacama Large Milli/submillimeter Array (ALMA) in SSA22 Field (ADF22). We analyze the ALMA 1.1-mm survey data, with an effective survey area of 5 arcmin2, frequency ranges of 253.1-256.8 and 269.1-272.8 GHz, angular resolution of 0{^''.}7 and rms noise of 0.8 mJy beam-1 at 36 km s-1 velocity resolution. We detect four line-emitter candidates with significance levels above 6σ. We identify one of the four sources as a CO(9-8) emitter at z = 3.1 in a member of the proto-cluster known in this field. Another line emitter with an optical counterpart is likely a CO(4-3) emitter at z = 0.7. The other two sources without any millimeter continuum or optical/near-infrared counterpart are likely to be [C II] emitter candidates at z = 6.0 and 6.5. The equivalent widths of the [C II] candidates are consistent with those of confirmed high-redshift [C II] emitters and candidates, and are a factor of 10 times larger than that of the CO(9-8) emitter detected in this search. The [C II] luminosity of the candidates are 4-7 × 108 L⊙. The star formation rates (SFRs) of these sources are estimated to be 10-20 M⊙ yr-1 if we adopt an empirical [C II] luminosity-SFR relation. One of them has a relatively low S/N ratio, but shows features characteristic of emission lines. Assuming that at least one of the two candidates is a [C II] emitter, we derive a lower limit of [C II]-based star formation rate density (SFRD) at z ˜ 6. The resulting value of >10-2 M⊙ yr-1 Mpc-3 is consistent with the dust-uncorrected UV-based SFRD. Future millimeter/submillimeter surveys can be used to detect a number of high-redshift line emitters, with which to study the star formation history in the early universe.

  13. Development of DOTA-Rituximab to be Labeled with 90Y for Radioimmunotherapy of B-cell Non-Hodgkin Lymphoma

    PubMed Central

    Johari doha, Fariba; Rahmani, Siyavash; Rikhtechi, Pedram; Rasaneh, Samira; Sheikholislam, Zahra; Shahhosseini, Soraya

    2017-01-01

    NHL is the most common hematologic cancer in adults. Rituximab is the FDA approved treatment of relapsed or refractory low grade B-cell Non-Hodgkin Lymphoma (NHL). But patients eventually become resistant to rituximab. Since lymphocytes and lymphoma cells are highly radiosensitive, low grade NHL that has relapsed or refractory to standard therapy is treated by RIT in which a beta-emitting radionuclide coupled to anti-CD20 antibody. The association of beta emitter radionuclide to rituximab enhances its therapeutic efficacy. The cells which lack antigen or cells which cannot be reached due to poor vascularization and intratumoral pressure in a bulky tumor would be irradiated and killed by cross fire effect of beta emitter. 90Y, a pure high energy β-emitter with a half-life of 64 h, a maximum energy of 2.28 MeV, and maximum board of 11.3 mm in tissue is radionuclide of choice for radioimmunotherapy of outpatient administration. In this study, rituximab was conjugated to DOTA and radiolabeled with 90YCl3. The stability, affinity, and immunoreactivity of radiolabeled antibody was determined in vitro and the conditions were optimized. Biodistribution studies were done in normal mice. The optimum conditions of conjugation and radiolabeling was 1-2 h at 37 °C and 1 h at 45 °C, respectively. Results showed approximately 4 DOTA molecules conjugated per antibody molecule. The purified antibody was stable and intact over 6 months stored at -20 °C. The result of immunoreactivity (≈70%), affinity (≈3 nM) and biodistribution in normal mice are acceptable. PMID:28979315

  14. High-Precision Half-Life Measurements for the Superallowed Fermi β+ Emitters 14O and 18Ne

    NASA Astrophysics Data System (ADS)

    Laffoley, A. T.; Andreoiu, C.; Austin, R. A. E.; Ball, G. C.; Bender, P. C.; Bidaman, H.; Bildstein, V.; Blank, B.; Bouzomita, H.; Cross, D. S.; Deng, G.; Diaz Varela, A.; Dunlop, M. R.; Dunlop, R.; Finlay, P.; Garnsworthy, A. B.; Garrett, P.; Giovinazzo, J.; Grinyer, G. F.; Grinyer, J.; Hadinia, B.; Jamieson, D. S.; Jigmeddorj, B.; Ketelhut, S.; Kisliuk, D.; Leach, K. G.; Leslie, J. R.; MacLean, A.; Miller, D.; Mills, B.; Moukaddam, M.; Radich, A. J.; Rajabali, M. M.; Rand, E. T.; Svensson, C. E.; Tardiff, E.; Thomas, J. C.; Turko, J.; Voss, P.; Unsworth, C.

    High-precision half-life measurements, at the level of ±0.04%, for the superallowed Fermi emitters 14O and 18Ne have been performed at TRIUMF's Isotope Separator and Accelerator facility. Using 3 independent detector systems, a gas-proportional counter, a fast plastic scintillator, and a high-purity germanium array, a series of direct β and γ counting measurements were performed for each of the isotopes. In the case of 14O, these measurements were made to help resolve an existing discrepancy between detection methods, whereas for 18Ne the half-life precision has been improved in anticipation of forthcoming high-precision branching ratio measurements.

  15. Concept of a staged FEL enabled by fast synchrotron radiation cooling of laser-plasma accelerated beam by solenoidal magnetic fields in plasma bubble

    NASA Astrophysics Data System (ADS)

    Seryi, Andrei; Lesz, Zsolt; Andreev, Alexander; Konoplev, Ivan

    2017-03-01

    A novel method for generating GigaGauss solenoidal fields in a laser-plasma bubble, using screw-shaped laser pulses, has been recently presented. Such magnetic fields enable fast synchrotron radiation cooling of the beam emittance of laser-plasma accelerated leptons. This recent finding opens a novel approach for design of laser-plasma FELs or colliders, where the acceleration stages are interleaved with laser-plasma emittance cooling stages. In this concept paper, we present an outline of what a staged plasma-acceleration FEL could look like, and discuss further studies needed to investigate the feasibility of the concept in detail.

  16. Emittance formula for slits and pepper-pot measurement

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  18. The clustering of Hβ +[OIII] and [OII] emitters since z ˜ 5: dependencies with line luminosity and stellar mass

    NASA Astrophysics Data System (ADS)

    Khostovan, A. A.; Sobral, D.; Mobasher, B.; Best, P. N.; Smail, I.; Matthee, J.; Darvish, B.; Nayyeri, H.; Hemmati, S.; Stott, J. P.

    2018-04-01

    We investigate the clustering properties of ˜7000 Hβ +[OIII] and [OII] narrowband-selected emitters at z ˜ 0.8 - 4.7 from the High-z Emission Line Survey. We find clustering lengths, r0, of 1.5 - 4.0 h-1 Mpc and minimum dark matter halo masses of 1010.7 - 12.1 M⊙ for our z = 0.8 - 3.2 Hβ +[OIII] emitters and r0˜2.0 - 8.3 h-1 Mpc and halo masses of 1011.5 - 12.6 M⊙ for our z = 1.5 - 4.7 [OII] emitters. We find r0 to strongly increase both with increasing line luminosity and redshift. By taking into account the evolution of the characteristic line luminosity, L⋆(z), and using our model predictions of halo mass given r0, we find a strong, redshift-independent increasing trend between L/L⋆(z) and minimum halo mass. The faintest Hβ +[OIII] emitters are found to reside in 109.5 M⊙ halos and the brightest emitters in 1013.0 M⊙ halos. For [OII] emitters, the faintest emitters are found in 1010.5 M⊙ halos and the brightest emitters in 1012.6 M⊙ halos. A redshift-independent stellar mass dependency is also observed where the halo mass increases from 1011 M⊙ to 1012.5 M⊙ for stellar masses of 108.5 M⊙ to 1011.5 M⊙, respectively. We investigate the interdependencies of these trends by repeating our analysis in a Lline - Mstar grid space for our most populated samples (Hβ +[OIII] z = 0.84 and [OII] z = 1.47) and find that the line luminosity dependency is stronger than the stellar mass dependency on halo mass. For L > L⋆ emitters at all epochs, we find a relatively flat trend with halo masses of 1012.5 - 13 M⊙ which may be due to quenching mechanisms in massive halos which is consistent with a transitional halo mass predicted by models.

  19. Self aligning electron beam gun having enhanced thermal and mechanical stability

    DOEpatents

    Scarpetti, R.D. Jr.; Parkison, C.D.; Switzer, V.A.; Lee, Y.J.; Sawyer, W.C.

    1995-05-16

    A compact, high power electron gun is disclosed having enhanced thermal and mechanical stability which incorporates a mechanically coupled, self aligning structure for the anode and cathode. The enhanced stability, and reduced need for realignment of the cathode to the anode and downstream optics during operation are achieved by use of a common support structure for the cathode and anode which requires no adjustment screws or spacers. The electron gun of the present invention also incorporates a modular design for the cathode, in which the electron emitter, its support structure, and the hardware required to attach the emitter assembly to the rest of the gun are a single element. This modular design makes replacement of the emitter simpler and requires no realignment after a new emitter has been installed. Compactness and a reduction in the possibility of high voltage breakdown are achieved by shielding the ``triple point`` where the electrode, insulator, and vacuum meet. The use of electric discharge machining (EDM) for fabricating the emitter allows for the accurate machining of the emitter into intricate shapes without encountering the normal stresses developed by standard emitter fabrication techniques. 12 Figs.

  20. Facility for assessing spectral normal emittance of solid materials at high temperature.

    PubMed

    Mercatelli, Luca; Meucci, Marco; Sani, Elisa

    2015-10-10

    Spectral emittance is a key topic in the study of new compositions, depositions, and mechanical machining of materials for solar absorption and for renewable energies in general. The present work reports on the realization and testing of a new experimental facility for the measurement of directional spectral emittance in the range of 2.5-20 μm. Our setup provides emittance spectral information in a completely controlled environment at medium-high temperatures up to 1200 K. We describe the layout and first tests on the device, comparing the results obtained for hafnium carbide and tantalum diboride ultrarefractory ceramic samples to previous quasi-monochromatic measurements carried out in the PROMES-CNRS (PROcedes, Materiaux et Energie Solaire- Centre National de la Recherche Scientifique, France) solar furnace, obtaining a good agreement. Finally, to assess the reliability of the widely used approach of estimating the spectral emittance from room-temperature reflectance spectrum, we compared the calculation in the 2.5-17 μm spectral range to the experimental high-temperature spectral emittance, obtaining that the spectral trend of calculated and measured curves is similar but the calculated emittance underestimates the measured value.

  1. Secondary electron ion source neutron generator

    DOEpatents

    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

  2. Efficient room-temperature source of polarized single photons

    DOEpatents

    Lukishova, Svetlana G.; Boyd, Robert W.; Stroud, Carlos R.

    2007-08-07

    An efficient technique for producing deterministically polarized single photons uses liquid-crystal hosts of either monomeric or oligomeric/polymeric form to preferentially align the single emitters for maximum excitation efficiency. Deterministic molecular alignment also provides deterministically polarized output photons; using planar-aligned cholesteric liquid crystal hosts as 1-D photonic-band-gap microcavities tunable to the emitter fluorescence band to increase source efficiency, using liquid crystal technology to prevent emitter bleaching. Emitters comprise soluble dyes, inorganic nanocrystals or trivalent rare-earth chelates.

  3. Electrically-inactive phosphorus re-distribution during low temperature annealing

    NASA Astrophysics Data System (ADS)

    Peral, Ana; Youssef, Amanda; Dastgheib-Shirazi, Amir; Akey, Austin; Peters, Ian Marius; Hahn, Giso; Buonassisi, Tonio; del Cañizo, Carlos

    2018-04-01

    An increased total dose of phosphorus (P dose) in the first 40 nm of a phosphorus diffused emitter has been measured after Low Temperature Annealing (LTA) at 700 °C using the Glow Discharge Optical Emission Spectrometry technique. This evidence has been observed in three versions of the same emitter containing different amounts of initial phosphorus. A stepwise chemical etching of a diffused phosphorus emitter has been carried out to prepare the three types of samples. The total P dose in the first 40 nm increases during annealing by 1.4 × 1015 cm-2 for the sample with the highly doped emitter, by 0.8 × 1015 cm-2 in the middle-doped emitter, and by 0.5 × 1015 cm-2 in the lowest-doped emitter. The presence of surface dislocations in the first few nanometers of the phosphorus emitter might play a role as preferential sites of local phosphorus gettering in phosphorus re-distribution, because the phosphorus gettering to the first 40 nm is lower when this region is etched stepwise. This total increase in phosphorus takes place even though the calculated electrically active phosphorus concentration shows a reduction, and the measured sheet resistance shows an increase after annealing at a low temperature. The reduced electrically active P dose is around 0.6 × 1015 cm-2 for all the emitters. This can be explained with phosphorus-atoms diffusing towards the surface during annealing, occupying electrically inactive configurations. An atomic-scale visual local analysis is carried out with needle-shaped samples of tens of nm in diameter containing a region of the highly doped emitter before and after LTA using Atom Probe Tomography, showing phosphorus precipitates of 10 nm and less before annealing and an increased density of larger precipitates after annealing (25 nm and less).

  4. Bias-free lateral terahertz emitters—A simulation study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Granzner, R., E-mail: ralf.granzner@tu-ilmenau.de; Schwierz, F.; Polyakov, V. M.

    2015-07-28

    The design and performance of bias-free InN-based THz emitters that exploit lateral photocurrents is studied by means of numerical simulations. We use a drift-diffusion model with adjusted carrier temperatures and mobilities. The applicability of this approach is demonstrated by a comparison with results from Monte-Carlo simulations. We consider a simple but robust lateral emitter concept using metal stripes with two different thicknesses with one of them being thin enough to be transparent for THz radiation. This arrangement can be easily multiplexed and the efficiency of this concept has already been demonstrated by experiment for GaAs substrates. In the present study,more » we consider InN, which is known to be an efficient photo-Dember emitter because of its superior transport properties. Our main focus is on the impact of the emitter design on the emission efficiency assuming different operation principles. Both the lateral photo-Dember (LPD) effect and built-in lateral field effects are considered. The appropriate choice of the metal stripe and window geometry as well as the impact of surface Fermi level pinning are investigated in detail, and design guidelines for efficient large area emitters using multiplexed structures are provided. We find that InN LPD emitters do not suffer from Fermi level pinning at the InN surface. The optimum emission efficiency is found for LPD emitter structures having 200 nm wide illumination windows and mask stripes. Emitter structures in which lateral electric fields are induced by the metal mask contacts can have a considerably higher efficiency than pure LPD emitters. In the best case, the THz emission of such structures is increased by one order of magnitude. Their optimum window size is 1 μm without the necessity of a partially transparent set of mask stripes.« less

  5. Development of a pepper pot emittance probe and its application for ECR ion beam studies.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kondrashev, S.; Barcikowski, A.; Mustapha, B.

    2009-07-21

    A pepper pot-scintillator screen system has been developed and used to measure the emittance of DC ion beams extracted from a high-intensity permanent magnet ECR ion source. The system includes a fast beam shutter with a minimum dwell time of 18 ms to reduce the degradation of the CsI(Tl) scintillator by DC ion beam irradiation and a CCD camera with a variable shutter speed in the range of 1 {micro}s-65 s. On-line emittance measurements are performed by an application code developed on a LabVIEW platform. The sensitivity of the device is sufficient to measure the emittance of DC ion beamsmore » with current densities down to about 100 nA/cm{sup 2}. The emittance of all ion species extracted from the ECR ion source and post-accelerated to an energy of 75-90 keV/charge have been measured downstream of the LEBT. As the mass-to-charge ratio of ion species increases, the normalized RMS emittances in both transverse phase planes decrease from 0.5-1.0 {pi} mm mrad for light ions to 0.05-0.09 {pi} mm mrad for highly charged {sup 209}Bi ions. The dependence of the emittance on ion's mass-to-charge ratio follows very well the dependence expected from beam rotation induced by decreasing ECR axial magnetic field. The measured emittance values cannot be explained by only ion beam rotation for all ion species and the contribution to emittance of ion temperature in plasma, non-linear electric fields and non-linear space charge is comparable or even higher than the contribution of ion beam rotation.« less

  6. Emittance of TD-NiCr after simulated reentry

    NASA Technical Reports Server (NTRS)

    Clark, R. K.; Dicus, D. L.; Lisagor, W. B.

    1978-01-01

    The effects of simulated reentry heating on the emittance of TD-NiCr were investigated. Groups of specimens with three different preconditioning treatments were exposed to 6, 24, and 30 half-hour simulated reentry exposure cycles in a supersonic arc tunnel at each of three conditions intended to produce surface temperatures of 1255, 1365, and 1475 K. Emittance was determined at 1300 K on specimens which were preconditioned only and specimens after completion of reentry simulation exposure. Oxide morphology and chemistry were studied by scanning electron microscopy and X-ray diffraction analysis. A consistent relationship was established between oxide morphology and total normal emittance. Specimens with coarser textured oxides tended to have lower emittances than specimens with finer textured oxides.

  7. Coupling of Molecular Emitters and Plasmonic Cavities beyond the Point-Dipole Approximation.

    PubMed

    Neuman, Tomáš; Esteban, Ruben; Casanova, David; García-Vidal, Francisco J; Aizpurua, Javier

    2018-04-11

    As the size of a molecular emitter becomes comparable to the dimensions of a nearby optical resonator, the standard approach that considers the emitter to be a point-like dipole breaks down. By adoption of a quantum description of the electronic transitions of organic molecular emitters, coupled to a plasmonic electromagnetic field, we are able to accurately calculate the position-dependent coupling strength between a plasmon and an emitter. The spatial distribution of excitonic and photonic quantum states is found to be a key aspect in determining the dynamics of molecular emission in ultrasmall cavities both in the weak and strong coupling regimes. Moreover, we show that the extreme localization of plasmonic fields leads to the selection rule breaking of molecular excitations.

  8. Strongly coupling a cavity to inhomogeneous ensembles of emitters: Potential for long-lived solid-state quantum memories

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Diniz, I.; Portolan, S.; Auffeves, A.

    2011-12-15

    We investigate theoretically the coupling of a cavity mode to a continuous distribution of emitters. We discuss the influence of the emitters' inhomogeneous broadening on the existence and on the coherence properties of the polaritonic peaks. We find that their coherence depends crucially on the shape of the distribution and not only on its width. Under certain conditions the coupling to the cavity protects the polaritonic states from inhomogeneous broadening, resulting in a longer storage time for a quantum memory based on emitter ensembles. When two different ensembles of emitters are coupled to the resonator, they support a peculiar collectivemore » dark state, which is also very attractive for the storage of quantum information.« less

  9. Enhancement of time images for photointerpretation

    NASA Technical Reports Server (NTRS)

    Gillespie, A. R.

    1986-01-01

    The Thermal Infrared Multispectral Scanner (TIMS) images consist of six channels of data acquired in bands between 8 and 12 microns, thus they contain information about both temperature and emittance. Scene temperatures are controlled by reflectivity of the surface, but also by its geometry with respect to the Sun, time of day, and other factors unrelated to composition. Emittance is dependent upon composition alone. Thus the photointerpreter may wish to enhance emittance information selectively. Because thermal emittances in real scenes vary but little, image data tend to be highly correlated along channels. Special image processing is required to make this information available for the photointerpreter. Processing includes noise removal, construction of model emittance images, and construction of false-color pictures enhanced by decorrelation techniques.

  10. Rare Earth Doped High Temperature Ceramic Selective Emitters

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Pal, AnnaMarie; Patton, Martin O.; Jenkins, Phillip P.

    1999-01-01

    As a result of their electron structure, rare earth ions in crystals at high temperature emit radiation in several narrow bands rather than in a continuous blackbody manner. This study develops a spectral emittance model for films of rare earth containing materials. Although there are several possible rare earth doped high temperature materials, this study was confined to rare earth aluminum garnets. Good agreement between experimental and theoretical spectral emittances was found for erbium, thulium and erbium-holmium aluminum garnets. Spectral emittances of these films are sensitive to temperature differences across the film. Emitter efficiency is also a sensitive function of temperature. For thulium aluminum garnet the efficiency is 0.38 at 1700 K but only 0.19 at 1262 K.

  11. Quantum Emitters in Two-Dimensional Structured Reservoirs in the Nonperturbative Regime

    NASA Astrophysics Data System (ADS)

    González-Tudela, A.; Cirac, J. I.

    2017-10-01

    We show that the coupling of quantum emitters to a two-dimensional reservoir with a simple band structure gives rise to exotic quantum dynamics with no analogue in other scenarios and which cannot be captured by standard perturbative treatments. In particular, for a single quantum emitter with its transition frequency in the middle of the band, we predict an exponential relaxation at a rate different from that predicted by Fermi's golden rule, followed by overdamped oscillations and slow relaxation decay dynamics. This is accompanied by directional emission into the reservoir. This directionality leads to a modification of the emission rate for few emitters and even perfect subradiance, i.e., suppression of spontaneous emission, for four quantum emitters.

  12. Cascaded two-photon nonlinearity in a one-dimensional waveguide with multiple two-level emitters

    PubMed Central

    Roy, Dibyendu

    2013-01-01

    We propose and theoretically investigate a model to realize cascaded optical nonlinearity with few atoms and photons in one-dimension (1D). The optical nonlinearity in our system is mediated by resonant interactions of photons with two-level emitters, such as atoms or quantum dots in a 1D photonic waveguide. Multi-photon transmission in the waveguide is nonreciprocal when the emitters have different transition energies. Our theory provides a clear physical understanding of the origin of nonreciprocity in the presence of cascaded nonlinearity. We show how various two-photon nonlinear effects including spatial attraction and repulsion between photons, background fluorescence can be tuned by changing the number of emitters and the coupling between emitters (controlled by the separation). PMID:23948782

  13. Low Emittance, High Brilliance Relativistic Electron Beams from a Laser-Plasma Accelerator

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Brunetti, E.; Shanks, R. P.; Manahan, G. G.

    2010-11-19

    Progress in laser wakefield accelerators indicates their suitability as a driver of compact free-electron lasers (FELs). High brightness is defined by the normalized transverse emittance, which should be less than 1{pi} mm mrad for an x-ray FEL. We report high-resolution measurements of the emittance of 125 MeV, monoenergetic beams from a wakefield accelerator. An emittance as low as 1.1{+-}0.1{pi} mm mrad is measured using a pepper-pot mask. This sets an upper limit on the emittance, which is comparable with conventional linear accelerators. A peak transverse brightness of 5x10{sup 15} A m{sup -1} rad{sup -1} makes it suitable for compact XUVmore » FELs.« less

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

    PubMed

    Gardette, Maryline; Papon, Janine; Bonnet, Mathilde; Desbois, Nicolas; Labarre, Pierre; Wu, Ting-Dee; Miot-Noirault, Elisabeth; Madelmont, Jean-Claude; Guerquin-Kern, Jean-Luc; Chezal, Jean-Michel; Moins, Nicole

    2011-12-01

    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 iodobenzamides or analogs are known to possess specific affinity for melanoma tissue. New heteroaromatic derivatives have been designed with a cytotoxic moiety and termed DNA intercalating agents. These compounds could be applied in targeted radionuclide therapy using (125)I, which emits Auger electrons and gives high-energy, 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 (125)I, the two compounds induced in vitro a significant radiotoxicity to B16F0 melanoma cells. Nevertheless, the acridine compound appeared more radiotoxic than the acridone compound. While cellular uptake was similar for both compounds, SIMS analysis and in vitro protocol showed a stronger affinity for melanin with acridone derivative, which was able to induce a predominant scavenging process in the melanosome and restrict access to the nucleus. In conclusion, the acridine derivative with a higher nuclear localization appeared a better candidate for application in targeted radionuclide therapy using (125)I.

  15. The Effect of Martian Dust on Radiator Performance

    NASA Technical Reports Server (NTRS)

    Hollingsworth, D. Keith; Witte, Larry C.; Hinke, Jaime; Hulbert, Kathryn

    2004-01-01

    Experiments were performed in which the effective emittance of three types of radiator Coatings was measured as Martian dust simulant was added to the radiator face. The apparatus consisted of multiple radiator coupons on which Carbondale Red Clay dust was deposited. The coupons were powered by electric heaters, using a guard-heating configuration to achieve the accuracy required for acceptable emittance calculations. The apparatus was containing in a vacuum chamber that featured a liquid-nitrogen cooled shroud that simulated the Martian sky temperature. Radiator temperatures ranged from 250 to 350 K with sky temperatures from 185 to 248 K. Results show that as dust was added to the radiator surfaces, the effective emittance of the high - emittance coatings decreased from near 0.9 to a value of about 0.5. A low-emittance control surface, polished aluminum, demonstrated a rise in effective emittance for thin dust layers, and then a decline as the dust layer thickened. This behavior is attributed to the conductive resistance caused by the dust layer.

  16. Highly efficient and stable organic light-emitting diodes with a greatly reduced amount of phosphorescent emitter

    PubMed Central

    Fukagawa, Hirohiko; Shimizu, Takahisa; Kamada, Taisuke; Yui, Shota; Hasegawa, Munehiro; Morii, Katsuyuki; Yamamoto, Toshihiro

    2015-01-01

    Organic light-emitting diodes (OLEDs) have been intensively studied as a key technology for next-generation displays and lighting. The efficiency of OLEDs has improved markedly in the last 15 years by employing phosphorescent emitters. However, there are two main issues in the practical application of phosphorescent OLEDs (PHOLEDs): the relatively short operational lifetime and the relatively high cost owing to the costly emitter with a concentration of about 10% in the emitting layer. Here, we report on our success in resolving these issues by the utilization of thermally activated delayed fluorescent materials, which have been developed in the past few years, as the host material for the phosphorescent emitter. Our newly developed PHOLED employing only 1 wt% phosphorescent emitter exhibits an external quantum efficiency of over 20% and a long operational lifetime of about 20 times that of an OLED consisting of a conventional host material and 1 wt% phosphorescent emitter. PMID:25985084

  17. Double emittance exchanger as a bunch compressor for the MaRIE XFEL electron beam line at 1 GeV

    NASA Astrophysics Data System (ADS)

    Malyzhenkov, Alexander; Carlsten, Bruce E.; Yampolsky, Nikolai A.

    2017-03-01

    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 a 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 beamline, and analyze the evolution of the eigen-emittances 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 an alternative version of an emittance exchanger with a reduced number of bending magnets to minimize the impact of CSR effects.

  18. Performance of a thermionic converter module utilizing emitter and collector heat pipes

    NASA Technical Reports Server (NTRS)

    Kroeger, E. W.; Morris, J. F.; Miskolczy, G.; Lieb, D. P.; Goodale, D. B.

    1978-01-01

    A thermionic converter module simulating a configuration for an out-of-core thermionic nuclear reactor was designed, fabricated, and tested. The module consists of three cylindrical thermionic converters. The tungsten emitter of the converter is heated by a tungsten, lithium heat pipe. The emitter heat pipes are immersed in a furnace, insulated by MULTI-FOIL thermal insulation, and heated by tungsten radiation filaments. The performance of each thermionic converter was characterized before assembly into the module. Dynamic voltage, current curves were taken using a 60 Hz sweep and computerized data acquisition over a range of emitter, collector, and cesium-reservoir temperatures. An output power of 215 W was observed at an emitter temperature of 1750 K and a collector temperature of 855 K for a two diode module. With a three diode module, an output power of 270 W was observed at an average emitter temperature of 1800 K and a Collector temperature of 875 K.

  19. A universal formula for the field enhancement factor

    NASA Astrophysics Data System (ADS)

    Biswas, Debabrata

    2018-04-01

    The field enhancement factor (FEF) is an important quantity in field emission calculations since the tunneling electron current depends very sensitively on its magnitude. The exact dependence of FEF on the emitter height h, the radius of curvature at the apex Ra, as well as the shape of the emitter base are still largely unknown. In this work, a universal formula for the field enhancement factor is derived for a single emitter. It depends on the ratio h/Ra and has the form γ a = ( 2 h / R a ) / [ α 1 ln ( 4 h / R a ) - α 2 ] , where α1 and α2 depend on the charge distribution on the emitter. Numerical results show that a simpler form γ a = ( 2 h / R a ) / [ ln ( 4 h / R a ) - α ] is equally valid with α depending on the emitter-base. Thus, for the hyperboloid, conical, and ellipsoid emitters, the value of α is 0, 0.88, and 2, while for the cylindrical base, α ≃ 2.6.

  20. Emittance measurements in Grumman 1 MeV beamline

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Debiak, T.; Gammel, G.; Melnychuk, S.

    1992-12-01

    The emittance of a 30 keV H{sup {minus}} beam has been measured with an Allison type electrostatic analyser at two positions separated by 85 cm along the Grumman 1 MeV beamline LEBT at low currents (about 4 mA, no Cs{sub 2}O additive in the source) and at higher currents (10-15 mA, with Cs{sub 2}O additive in the source). No emittance growth was observed between the two positions, but, at the higher current level, the emittance was about 60% higher than at the low current level ({Sigma}{sub n},rms = .0045 {pi} cm-mrad vs. 0070 {pi} cm-mrad). Argon was then introduced upmore » to a partial pressure of 4x10{sup {minus}5} torr, and the emittance decreased back to a range corresponding to that found at the lower currents. However, beam noise was observed at the downstream position, and there is evidence for a small amount of emittance growth (<20%) between the two positions.« less

  1. Theoretical investigation of confocal microscopy using an elliptically polarized cylindrical vector laser beam: Visualization of quantum emitters near interfaces

    NASA Astrophysics Data System (ADS)

    Boichenko, Stepan

    2018-04-01

    We theoretically study laser-scanning confocal fluorescence microscopy using elliptically polarized cylindrical vector excitation light as a tool for visualization of arbitrarily oriented single quantum dipole emitters located (1) near planar surfaces enhancing fluorescence, (2) in a thin supported polymer film, (3) in a freestanding polymer film, and (4) in a dielectric planar microcavity. It is shown analytically that by using a tightly focused azimuthally polarized beam, it is possible to exclude completely the orientational dependence of the image intensity maximum of a quantum emitter that absorbs light as a pair of incoherent independent linear dipoles. For linear dipole quantum emitters, the orientational independence degree higher than 0.9 can normally be achieved (this quantity equal to 1 corresponds to completely excluded orientational dependence) if the collection efficiency of the microscope objective and the emitter's total quantum yield are not strongly orientationally dependent. Thus, the visualization of arbitrarily oriented single quantum emitters by means of the studied technique can be performed quite efficiently.

  2. Generalized superradiant assembly for nanophotonic thermal emitters

    NASA Astrophysics Data System (ADS)

    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.

  3. Directional emittance surface measurement system and process

    NASA Technical Reports Server (NTRS)

    Puram, Chith K. (Inventor); Daryabeigi, Kamran (Inventor); Wright, Robert (Inventor); Alderfer, David W. (Inventor)

    1994-01-01

    Apparatus and process for measuring the variation of directional emittance of surfaces at various temperatures using a radiometric infrared imaging system. A surface test sample is coated onto a copper target plate provided with selective heating within the desired incremental temperature range to be tested and positioned onto a precision rotator to present selected inclination angles of the sample relative to the fixed positioned and optically aligned infrared imager. A thermal insulator holder maintains the target plate on the precision rotator. A screen display of the temperature obtained by the infrared imager, and inclination readings are provided with computer calculations of directional emittance being performed automatically according to equations provided to convert selected incremental target temperatures and inclination angles to relative target directional emittance values. The directional emittance of flat black lacquer and an epoxy resin measurements obtained are in agreement with the predictions of the electromagnetic theory and with directional emittance data inferred from directional reflectance measurements made on a spectrophotometer.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Malyzhenkov, Alexander; Yampolsky, Nikolai; Carlsten, Bruce Eric

    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 tomore » 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.« less

  5. Production of low-Z ions in the Dresden superconducting electron ion beam source for medical particle therapy.

    PubMed

    Zschornack, G; Schwan, A; Ullmann, F; Grossmann, F; Ovsyannikov, V P; Ritter, E

    2012-02-01

    We report on experiments with a new superconducting electron beam ion source (EBIS-SC), the Dresden EBIS-SC, with the objective to meet the main requirements for their application in particle-therapy facilities. Synchrotrons as well as innovative accelerator concepts, such as high-gradient linacs which are driven by a large-current cyclotron (CYCLINACS) and direct drive RF linear accelerators may benefit from the advantages of EBISs in regard to their functional principle. First experimental studies of the production of low-Z ions such as H(+), H(2)(+), H(3)(+), C(4+), and C(6+) are presented. Particular attention is paid to the ion output, i.e., the number of ions per pulse and per second, respectively. Important beam parameters in this context are, among others, ion pulse shaping, pulse repetition rates, beam emittance, and ion energy spread.

  6. Radium-223 in the treatment of bone metastasis in patients with castration-resistant prostate cancer. Review and procedure.

    PubMed

    Orcajo-Rincon, J; Caresia-Aróztegui, A P; Del Puig Cózar-Santiago, M; García-Garzón, J R; de Arcocha-Torres, M; Delgado-Bolton, R C; García-Velloso, M J; Alvarez-Ruiz, S; García-Vicente, A M

    2018-04-13

    Bone metastatic disease is the main cause of morbidity / mortality in patients with prostate cancer, presenting frequently as bone pain, pathological fractures or spinal cord compression, which requires early and timely therapy. Although, for the moment, the therapeutic window for its use has not been definitively established, radium-223 ( 223 Ra), an alpha particle emitter, has proved to be an effective therapeutic tool, pre or post-chemotherapy, in patients with castration-resistant prostate cancer with symptomatic bone metastases and absence of visceral metastases, significantly modifying the prognosis of the disease. It is therefore imperative to define the ideal scenarios and the correct protocol for the use of this therapy and thus offer the greatest possible clinical benefit to the patient. Copyright © 2018 Sociedad Española de Medicina Nuclear e Imagen Molecular. Publicado por Elsevier España, S.L.U. All rights reserved.

  7. Determination of radionuclides and radiochemical impurities produced by in-house cyclotron irradiation and subsequent radiosynthesis of PET tracers.

    PubMed

    Ishiwata, Kiichi; Hayashi, Kunpei; Sakai, Masanari; Kawauchi, Sugio; Hasegawa, Hideaki; Toyohara, Jun

    2017-01-01

    To elucidate the radionuclides and radiochemical impurities included in radiosynthesis processes of positron emission tomography (PET) tracers. Target materials and PET tracers were produced using a cyclotron/synthesis system from Sumitomo Heavy Industry. Positron and γ-ray emitting radionuclides were quantified by measuring radioactivity decay and using the high-purity Ge detector, respectively. Radiochemical species in gaseous and aqueous target materials were analyzed by gas and ion chromatography, respectively. Target materials had considerable levels of several positron emitters in addition to the positron of interest, and in the case of aqueous target materials extremely low levels of many γ-emitters. Five 11 C-, 15 O-, or 18 F-labeled tracers produced from gaseous materials via chemical reactions had no radionuclidic impurities, whereas 18 F-FDG, 18 F-NaF, and 13 N-NH 3 produced from aqueous materials had several γ-emitters as well as impure positron emitters. 15 O-Labeled CO 2 , O 2 , and CO had a radionuclidic impurity 13 N-N 2 (0.5-0.7 %). Target materials had several positron emitters other than the positron of interest, and extremely low level γ-emitters in the case of aqueous materials. PET tracers produced from gaseous materials except for 15 O-labeled gases had no impure radionuclides, whereas those derived from aqueous materials contained acceptable levels of impure positron emitters and extremely low levels of several γ-emitters.

  8. Wavelength locking of single emitters and multi-emitter modules: simulation and experiments

    NASA Astrophysics Data System (ADS)

    Yanson, Dan; Rappaport, Noam; Peleg, Ophir; Berk, Yuri; Dahan, Nir; Klumel, Genady; Baskin, Ilya; Levy, Moshe

    2016-03-01

    Wavelength-stabilized high-brightness single emitters are commonly used in fiber-coupled laser diode modules for pumping Yb-doped lasers at 976 nm, and Nd-doped ones at 808 nm. We investigate the spectral behavior of single emitters under wavelength-selective feedback from a volume Bragg (or hologram) grating (VBG) in a multi-emitter module. By integrating a full VBG model as a multi-layer thin film structure with commercial raytracing software, we simulated wavelength locking conditions as a function of beam divergence and angular alignment tolerances. Good correlation between the simulated VBG feedback strength and experimentally measured locking ranges, in both VBG misalignment angle and laser temperature, is demonstrated. The challenges of assembling multi-emitter modules based on beam-stacked optical architectures are specifically addressed, where the wavelength locking conditions must be achieved simultaneously with high fiber coupling efficiency for each emitter in the module. It is shown that angular misorientation between fast and slow-axis collimating optics can have a dramatic effect on the spectral and power performance of the module. We report the development of our NEON-S wavelength-stabilized fiber laser pump module, which uses a VBG to provide wavelength-selective optical feedback in the collimated portion of the beam. Powered by our purpose-developed high-brightness single emitters, the module delivers 47 W output at 11 A from an 0.15 NA fiber and a 0.3 nm linewidth at 976 nm. Preliminary wavelength-locking results at 808 nm are also presented.

  9. Effect of longitudinal aberration in an ion-optical system on the properties of a focused beam

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Getmanov, V.N.; Ikryanov, I.M.; Savchenko, O.Ya.

    1994-11-01

    Modelling of the processes involved in the passage of a beam through a system of high-voltage electrodes with allowance made for the thermal and grid spreads of transverse particle velocities constitutes a three-dimensional problem that is difficult to solve with modern computers. In the present work, an analytic method has been developed that reduces this problem to a two-dimensional one. The method corresponds to approximating a marked longitudinal aberration in an ion-optical system (IOS), when the effective emittance of the beam during its high-voltage shaping increases severalfold, this being characteristic of all IOS know thus far. Fully justified in thismore » case is the statement that a unique relationship exists between the coordinates r and z, which respectively characterize the location of the particle on the emitter and the point of intersection of the axis by the particle (or the point of maximum approach of the particle to the axis), and also between r and {alpha} ({alpha}being the angle between the particle trajectory in the focusing region and the axis of the system). This statement leads to a hyperbolic law of increase in current density in the central portion of the focused beam and thus confirms the validity of this law. The calculations were compared with experimental data on the focusing of a 0.4-MeV proton beam with a current of 20-75 mA and a diameter of 2-5 mm in the crossover under conditions in which the effective emittance of the beam, as a result of aberrations during its high-voltage shaping, increased by a factor of 3 or more (in kilovolts), and the calculated trajectories for 20 of 40 mm at the emitter are shown, where the markers D8 and D9 denote the positions of multiwire beam profile sensors.« less

  10. Sci-Thur AM: YIS – 01: New technologies for astatine-211 targeted alpha therapy research

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Crawford, Jason; Yang, Hua; Schaffer, Paul

    Purpose: The short-range, densely ionizing α-particles emitted by {sup 211}At (t{sub 1/2}=7.2h) are well suited for the treatment of diffuse microscopic disease, using cancer targeting biomolecules. {sup 211}At availability is limited by the rarity of α-cyclotrons required for standard production. Image-based dosimetry is also limited for {sup 211}At, which emits low intensity X-rays. Our goal was to leverage state-of-the-art infrastructure at TRIUMF to produce and evaluate two related isotopes, {sup 211}Rn (t{sub 1/2}=14.6h, 73% decay to {sup 211}At) as a generator for {sup 211}At, and {sup 209}At (t{sub 1/2}=5.4h, X-ray/gamma-ray emitter) as a novel 211At surrogate for preclinical imaging studies.more » Methods: Produced by spallation of uranium with 480 MeV protons, mass separated ion beams of short-lived francium isotopes were implanted into NaCl targets where {sup 211}Rn or {sup 209}At were produced by radioactive decay, in situ. {sup 211}Rn was transferred to dodecane from which {sup 211}At was efficiently extracted and evaluated for clinical applicability. High energy SPECT/CT was evaluated for measuring {sup 209}At activity distributions in mice and phantoms. Results: Our small scale {sup 211}Rn/{sup 211}At generator system provided high purity {sup 211}At samples. The methods are immediately scalable to the level of radioactivity required for in vivo experiments with {sup 211}At. {sup 209}At-based high energy SPECT imaging was determined suitable for pursuing image-based dosimetry in mouse tumour models. In the future, we will utilize quantitative {sup 209}At-SPECT for image-based dose calculations. Conclusion: These early studies provided a foundation for future endeavours with {sup 211}At-based α-therapy. Canada is now significantly closer to clinical targeted α-therapy of cancer.« less

  11. Secondary electron ion source neutron generator

    DOEpatents

    Brainard, J.P.; McCollister, D.R.

    1998-04-28

    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 is disclosed. The target contains occluded deuterium, tritium, or a mixture thereof. 4 figs.

  12. Diamond fiber field emitters

    DOEpatents

    Blanchet-Fincher, Graciela B.; Coates, Don M.; Devlin, David J.; Eaton, David F.; Silzars, Aris K.; Valone, Steven M.

    1996-01-01

    A field emission electron emitter comprising an electrode formed of at least one diamond, diamond-like carbon or glassy carbon composite fiber, said composite fiber having a non-diamond core and a diamond, diamond-like carbon or glassy carbon coating on said non-diamond core, and electronic devices employing such a field emission electron emitter.

  13. Direct Observation of Ultralow Vertical Emittance using a Vertical Undulator - presentation slides

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wootton, Kent

    2015-09-17

    Direct emittance measurement based on vertical undulator is discussed. Emittance was evaluated from peak ratios, the smallest measured being =0.9 ±0.3 pm rad. The angular distribution of undulator radiation departs from Gaussian approximations, a fact of which diffraction-limited light sources should be aware.

  14. Development of techniques and associated instrumentation for high temperature emissivity measurements

    NASA Technical Reports Server (NTRS)

    Cunnington, G. R.; Funaa, A. I.; Cassady, P. E.

    1973-01-01

    Studies were made to develop a test apparatus for the measurement of total emittance of materials under repeated exposure to simulated earth entry conditions. As no existing test facility met the emittance measurement and entry simulation goals, a new apparatus was designed, fabricated and checked out. This apparatus has the capability of performing total and spectral emittance measurements during cyclic temperature and pressure exposure under sonic and supersonic flow conditions. Emittance measurements were performed on a series of oxidized superalloys, silicide coated columbium alloys and ceramic coatings.

  15. Quantum many-body correlations in collective phonon-excitations

    NASA Astrophysics Data System (ADS)

    Droenner, Leon; Kabuss, Julia; Carmele, Alexander

    2018-02-01

    We present a theoretical study of a many-emitter phonon laser based on optically driven semiconductor quantum dots placed within an acoustic nanocavity. A transformation of the phonon laser Hamiltonian leads to a Tavis-Cummings type interaction with an unexpected additional many-emitter energy shift. This many-emitter interaction with the cavity mode results in a variety of phonon resonances which dependent strongly on the number of participating emitters. These collective resonances show the highest phonon output. Furthermore, we show that the output can be increased even more via lasing at the two phonon resonance.

  16. Thermophotovoltaic energy conversion system having a heavily doped n-type region

    DOEpatents

    DePoy, David M.; Charache, Greg W.; Baldasaro, Paul F.

    2000-01-01

    A thermophotovoltaic (TPV) energy conversion semiconductor device is provided which incorporates a heavily doped n-type region and which, as a consequence, has improved TPV conversion efficiency. The thermophotovoltaic energy conversion device includes an emitter layer having first and second opposed sides and a base layer in contact with the first side of the emitter layer. A highly doped n-type cap layer is formed on the second side of the emitter layer or, in another embodiment, a heavily doped n-type emitter layer takes the place of the cap layer.

  17. High power telecommunication-compatible photoconductive terahertz emitters based on plasmonic nano-antenna arrays.

    PubMed

    Yardimci, Nezih Tolga; Lu, Hong; Jarrahi, Mona

    2016-11-07

    We present a high-power and broadband photoconductive terahertz emitter operating at telecommunication optical wavelengths, at which compact and high-performance fiber lasers are commercially available. The presented terahertz emitter utilizes an ErAs:InGaAs substrate to achieve high resistivity and short carrier lifetime characteristics required for robust operation at telecommunication optical wavelengths. It also uses a two-dimensional array of plasmonic nano-antennas to offer significantly higher optical-to-terahertz conversion efficiencies compared to the conventional photoconductive emitters, while maintaining broad operation bandwidths. We experimentally demonstrate pulsed terahertz radiation over 0.1-5 THz frequency range with the power levels as high as 300  μ W. This is the highest-reported terahertz radiation power from a photoconductive emitter operating at telecommunication optical wavelengths.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhou, F.; Bohler, D.; Ding, Y.

    2015-12-07

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

  19. Engineering and Localization of Quantum Emitters in Large Hexagonal Boron Nitride Layers.

    PubMed

    Choi, Sumin; Tran, Toan Trong; Elbadawi, Christopher; Lobo, Charlene; Wang, Xuewen; Juodkazis, Saulius; Seniutinas, Gediminas; Toth, Milos; Aharonovich, Igor

    2016-11-02

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

  20. Localization of Narrowband Single Photon Emitters in Nanodiamonds.

    PubMed

    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.

  1. Transparent conductor-embedding nanocones for selective emitters: optical and electrical improvements of Si solar cells

    PubMed Central

    Kim, Joondong; Yun, Ju-Hyung; Kim, Hyunyub; Cho, Yunae; Park, Hyeong-Ho; Kumar, M. Melvin David; Yi, Junsin; Anderson, Wayne A.; Kim, Dong-Wook

    2015-01-01

    Periodical nanocone-arrays were employed in an emitter region for high efficient Si solar cells. Conventional wet-etching process was performed to form the nanocone-arrays for a large area, which spontaneously provides the graded doping features for a selective emitter. This enables to lower the electrical contact resistance and enhances the carrier collection due to the high electric field distribution through a nanocone. Optically, the convex-shaped nanocones efficiently reduce light-reflection and the incident light is effectively focused into Si via nanocone structure, resulting in an extremely improved the carrier collection performances. This nanocone-arrayed selective emitter simultaneously satisfies optical and electrical improvement. We report the record high efficiency of 16.3% for the periodically nanoscale patterned emitter Si solar cell. PMID:25787933

  2. Transparent conductor-embedding nanocones for selective emitters: optical and electrical improvements of Si solar cells.

    PubMed

    Kim, Joondong; Yun, Ju-Hyung; Kim, Hyunyub; Cho, Yunae; Park, Hyeong-Ho; Kumar, M Melvin David; Yi, Junsin; Anderson, Wayne A; Kim, Dong-Wook

    2015-03-19

    Periodical nanocone-arrays were employed in an emitter region for high efficient Si solar cells. Conventional wet-etching process was performed to form the nanocone-arrays for a large area, which spontaneously provides the graded doping features for a selective emitter. This enables to lower the electrical contact resistance and enhances the carrier collection due to the high electric field distribution through a nanocone. Optically, the convex-shaped nanocones efficiently reduce light-reflection and the incident light is effectively focused into Si via nanocone structure, resulting in an extremely improved the carrier collection performances. This nanocone-arrayed selective emitter simultaneously satisfies optical and electrical improvement. We report the record high efficiency of 16.3% for the periodically nanoscale patterned emitter Si solar cell.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yang, Zhichao, E-mail: zcyang.phys@gmail.com; Zhang, Yuewei; Krishnamoorthy, Sriram

    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.

  4. High power telecommunication-compatible photoconductive terahertz emitters based on plasmonic nano-antenna arrays

    PubMed Central

    Yardimci, Nezih Tolga; Lu, Hong; Jarrahi, Mona

    2016-01-01

    We present a high-power and broadband photoconductive terahertz emitter operating at telecommunication optical wavelengths, at which compact and high-performance fiber lasers are commercially available. The presented terahertz emitter utilizes an ErAs:InGaAs substrate to achieve high resistivity and short carrier lifetime characteristics required for robust operation at telecommunication optical wavelengths. It also uses a two-dimensional array of plasmonic nano-antennas to offer significantly higher optical-to-terahertz conversion efficiencies compared to the conventional photoconductive emitters, while maintaining broad operation bandwidths. We experimentally demonstrate pulsed terahertz radiation over 0.1–5 THz frequency range with the power levels as high as 300 μW. This is the highest-reported terahertz radiation power from a photoconductive emitter operating at telecommunication optical wavelengths. PMID:27916999

  5. Development of techniques and associated instrumentation for high temperature emissivity measurements

    NASA Technical Reports Server (NTRS)

    Cunnington, G. R.; Funai, A. I.

    1972-01-01

    The progress during the sixth quarterly period is reported on construction and assembly of a test facility to determine the high temperature emittance properties of candidate thermal protection system materials for the space shuttle. This facility will provide simulation of such reentry environment parameters as temperature, pressure, and gas flow rate to permit studies of the effects of these parameters on the emittance stability of the materials. Also reported are the completed results for emittance tests on a set of eight Rene 41 samples and one anodized titanium alloy sample which were tested at temperatures up to 1600 F in vacuum. The data includes calorimetric determinations of total hemispherical emittance, radiometric determinations of total and spectral normal emittance, and pre- and post-test room temperature reflectance measurements.

  6. Recent progress of 638-nm high-power broad area laser diodes in Mitsubishi Electric

    NASA Astrophysics Data System (ADS)

    Kuramoto, Kyosuke; Abe, Shinji; Miyashita, Motoharu; Nishida, Takehiro; Yagi, Tetsuya

    2018-02-01

    Laser based displays have gathered much attention because only the displays can express full color gamut of Ultra-HDTV, ITU-R BT.2020. One of the displays uses the lasers under pulse such as a single spatial light modulator (SLM) projector, and the other does ones under CW such as a multiple SLM projector and a liquid crystal display. Both types require high-power lasers because brightness is the most important factor in the market. We developed two types of 638-nm multi-emitter high-power BA-LDs assembled on Φ9.0-TO, that is, triple emitter for pulse and dual emitter for CW. The triple emitter LD emitted exceeding 6.0 W peak power under 25°C, frequency of 120 Hz, and duty of 30%. At high temperature, 55°C, the peak power was approximately 2.9W. The dual emitter emitted exceeding 3.0W under 25°C, CW. It emitted up to 1.7 W at 55°C. WPE of the dual emitter reached 40.5% at Tc of 25°C, which is the world highest in 638-nm LD under CW to the best of our knowledge, although that of the triple emitter was 38.1%. Both LDs may be suitable for laser based display applications.

  7. High efficiency radioisotope thermophotovoltaic prototype generator

    NASA Technical Reports Server (NTRS)

    Avery, James E.; Samaras, John E.; Fraas, Lewis M.; Ewell, Richard

    1995-01-01

    A radioisotope thermophotovoltaic generator space power system (RTPV) is lightweight, low-cost alternative to the present radioisotope thermoelectric generator system (RTG). The fabrication of such an RTPV generator has recently become feasible as the result of the invention of the GaSb infrared sensitive photovoltaic cell. Herein, we present the results of a parametric study of emitters and optical filters in conjuction with existing data on gallium antimonide cells. We compare a polished tungsten emitter with an Erbia selective emitter for use in combination with a simple dielectric filter and a gallium antimonide cell array. We find that the polished tungsten emitter is by itself a very selective emitter with low emissivity beyond 4 microns. Given a gallium antimonide cell and a tungsten emitter, a simple dielectric filter can be designed to transmit radiant energy below 1.7 microns and to reflect radiant energy between 1.7 and 4 microns back to the emitter. Because of the low long wavelength emissivity associated with the polished tungsten emitter, this simple dielectric filter then yields very respectable system performance. Also as a result of the longer wavelength fall-off in the tungsten emissivity curve, the radiation energy peak for a polished tungsten emitter operating at 1300 K shifts to shorter wavelengths relative to the blackbody spectrum so that the radiated energy peak falls right at the gallium antimonide cell bandedge. The result is that the response of the gallium antimonide cell is well matched to a polished tungsten emitter. We propose, therefore, to fabricate an operating prototype of a near term radioisotope thermophotovoltaic generator design consisting of a polished tungsten emitter, standard gallium antimonide cells, and a near-term dielectric filter. The Jet Propulsion Laboratory will design and build the thermal cavity, and JX Crystals will fabricate the gallium antimonide cells, dielectric filters, and resultant receiver panels. With 250 Watts of heat input, we expect this prototype to produce over 300 Watts of electrical energy output for a system energy conversion efficiency of over 12%. This low risk, near term design provides advances relative to present radioisotope thermophotovoltaic generators and has the additional advantage of allowing component and system development and testing to begin immediately. Improved cells and filters can easily be incorporated in this baseline system if they should become available in the future.

  8. High efficiency radioisotope thermophotovoltaic prototype generator

    NASA Astrophysics Data System (ADS)

    Avery, James E.; Samaras, John E.; Fraas, Lewis M.; Ewell, Richard

    1995-10-01

    A radioisotope thermophotovoltaic generator space power system (RTPV) is lightweight, low-cost alternative to the present radioisotope thermoelectric generator system (RTG). The fabrication of such an RTPV generator has recently become feasible as the result of the invention of the GaSb infrared sensitive photovoltaic cell. Herein, we present the results of a parametric study of emitters and optical filters in conjuction with existing data on gallium antimonide cells. We compare a polished tungsten emitter with an Erbia selective emitter for use in combination with a simple dielectric filter and a gallium antimonide cell array. We find that the polished tungsten emitter is by itself a very selective emitter with low emissivity beyond 4 microns. Given a gallium antimonide cell and a tungsten emitter, a simple dielectric filter can be designed to transmit radiant energy below 1.7 microns and to reflect radiant energy between 1.7 and 4 microns back to the emitter. Because of the low long wavelength emissivity associated with the polished tungsten emitter, this simple dielectric filter then yields very respectable system performance. Also as a result of the longer wavelength fall-off in the tungsten emissivity curve, the radiation energy peak for a polished tungsten emitter operating at 1300 K shifts to shorter wavelengths relative to the blackbody spectrum so that the radiated energy peak falls right at the gallium antimonide cell bandedge. The result is that the response of the gallium antimonide cell is well matched to a polished tungsten emitter. We propose, therefore, to fabricate an operating prototype of a near term radioisotope thermophotovoltaic generator design consisting of a polished tungsten emitter, standard gallium antimonide cells, and a near-term dielectric filter. The Jet Propulsion Laboratory will design and build the thermal cavity, and JX Crystals will fabricate the gallium antimonide cells, dielectric filters, and resultant receiver panels. With 250 Watts of heat input, we expect this prototype to produce over 300 Watts of electrical energy output for a system energy conversion efficiency of over 12%. This low risk, near term design provides advances relative to present radioisotope thermophotovoltaic generators and has the additional advantage of allowing component and system development and testing to begin immediately. Improved cells and filters can easily be incorporated in this baseline system if they should become available in the future.

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

    DOEpatents

    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.

  10. Design of general apochromatic drift-quadrupole beam lines

    NASA Astrophysics Data System (ADS)

    Lindstrøm, C. A.; Adli, E.

    2016-07-01

    Chromatic errors are normally corrected using sextupoles in regions of large dispersion. In low emittance linear accelerators, use of sextupoles can be challenging. Apochromatic focusing is a lesser-known alternative approach, whereby chromatic errors of Twiss parameters are corrected without the use of sextupoles, and has consequently been subject to renewed interest in advanced linear accelerator research. Proof of principle designs were first established by Montague and Ruggiero and developed more recently by Balandin et al. We describe a general method for designing drift-quadrupole beam lines of arbitrary order in apochromatic correction, including analytic expressions for emittance growth and other merit functions. Worked examples are shown for plasma wakefield accelerator staging optics and for a simple final focus system.

  11. Reliability and efficacy of organic passivation for polycrystalline silicon solar cells at room temperature

    NASA Astrophysics Data System (ADS)

    Shinde, Onkar S.; Funde, Adinath M.; Jadkar, Sandesh R.; Dusane, Rajiv O.; Dhere, Neelkanth G.; Ghaisas, Subhash V.

    2016-09-01

    Oleylamine is used as a passivating layer instead of commercial high temperature SiNx. Oleylamine coating applied on the n-type emitter side with p-type base polycrystalline silicon solar cells at room temperature using a simple spin coating method. It has been observed that there is 16% increase in efficiency after Oleylamine coating. Further, the solar cell was subjected to standard characterization namely current-voltage measurement for electrical parameters and Fourier transform infrared spectroscopy to understand the interaction of emitter surface and passivating Oleylamine. However, the passivation layer is not stable due to the reaction between Oleylamine and ambient air content such as humidity and carbon dioxide. This degradation can be prevented with suitable overcoating.

  12. Depletion layer recombination effects on the radiation damage hardness of gallium arsenide cells

    NASA Technical Reports Server (NTRS)

    Garlick, G. F. J.

    1985-01-01

    The significant effect of junction depletion layer recombination on the efficiency of windowed GaAs cells was demonstrated. The effect becomes more pronounced as radiation damage occurs. The depletion is considered for 1 MeV electron fluences up to 10 to the 16th power e/sq m. The cell modeling separates damage in emitter and base or buffer layers using different damage coefficients is reported. The lower coefficient for the emitter predicts less loss of performance at fluences greater than 10 to the 15th power e/sq cm. A method for obtaining information on junction recombination effects as damage proceeds is described; this enables a more complete diagnosis of damage to be made.

  13. Massively parallel diffuse optical tomography

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sandusky, John V.; Pitts, Todd A.

    Diffuse optical tomography systems and methods are described herein. In a general embodiment, the diffuse optical tomography system comprises a plurality of sensor heads, the plurality of sensor heads comprising respective optical emitter systems and respective sensor systems. A sensor head in the plurality of sensors heads is caused to act as an illuminator, such that its optical emitter system transmits a transillumination beam towards a portion of a sample. Other sensor heads in the plurality of sensor heads act as observers, detecting portions of the transillumination beam that radiate from the sample in the fields of view of themore » respective sensory systems of the other sensor heads. Thus, sensor heads in the plurality of sensors heads generate sensor data in parallel.« less

  14. Robust lanthanide emitters in polyelectrolyte thin films for photonic applications

    NASA Astrophysics Data System (ADS)

    Greenspon, Andrew S.; Marceaux, Brandt L.; Hu, Evelyn L.

    2018-02-01

    Trivalent lanthanides provide stable emission sources at wavelengths spanning the ultraviolet through the near infrared with uses in telecommunications, lighting, and biological sensing and imaging. We describe a method for incorporating an organometallic lanthanide complex within polyelectrolyte multilayers, producing uniform, optically active thin films on a variety of substrates. These films demonstrate excellent emission with narrow linewidths, stable over a period of months, even when bound to metal substrates. Utilizing different lanthanides such as europium and terbium, we are able to easily tune the resulting wavelength of emission of the thin film. These results demonstrate the suitability of this platform as a thin film emitter source for a variety of photonic applications such as waveguides, optical cavities, and sensors.

  15. High-brightness 800nm fiber-coupled laser diodes

    NASA Astrophysics Data System (ADS)

    Berk, Yuri; Levy, Moshe; Rappaport, Noam; Tessler, Renana; Peleg, Ophir; Shamay, Moshe; Yanson, Dan; Klumel, Genadi; Dahan, Nir; Baskin, Ilya; Shkedi, Lior

    2014-03-01

    Fiber-coupled laser diodes have become essential sources for fiber laser pumping and direct energy applications. Single emitters offer reliable multi-watt output power from a 100 m lateral emission aperture. By their combination and fiber coupling, pump powers up to 100 W can be achieved from a low-NA fiber pigtail. Whilst in the 9xx nm spectral range the single emitter technology is very mature with <10W output per chip, at 800nm the reliable output power from a single emitter is limited to 4 W - 5 W. Consequently, commercially available fiber coupled modules only deliver 5W - 15W at around 800nm, almost an order of magnitude down from the 9xx range pumps. To bridge this gap, we report our advancement in the brightness and reliability of 800nm single emitters. By optimizing the wafer structure, laser cavity and facet passivation process we have demonstrated QCW device operation up to 19W limited by catastrophic optical damage to the 100 μm aperture. In CW operation, the devices reach 14 W output followed by a reversible thermal rollover and a complete device shutdown at high currents, with the performance fully rebounded after cooling. We also report the beam properties of our 800nm single emitters and provide a comparative analysis with the 9xx nm single emitter family. Pump modules integrating several of these emitters with a 105 μm / 0.15 NA delivery fiber reach 35W in CW at 808 nm. We discuss the key opto-mechanical parameters that will enable further brightness scaling of multi-emitter pump modules.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chouhan, V., E-mail: vchouhan@post.kek.jp, E-mail: vijaychouhan84@gmail.com; Noguchi, T.; Kato, S.

    The authors report a detail study on the emission properties of field emitter array (FEA) of micro-circular emitters of multiwall carbon nanotubes (CNTs). The FEAs were fabricated on patterned substrates prepared with an array of circular titanium (Ti) islands on titanium nitride coated tantalum substrates. CNTs were rooted into these Ti islands to prepare an array of circular emitters. The circular emitters were prepared in different diameters and pitches in order to optimize their structure for acquiring a high emission current. The pitch was varied from 0 to 600 μm, while a diameter of circular emitters was kept constant to bemore » 50 μm in order to optimize a pitch. For diameter optimization, a diameter was changed from 50 to 200 μm while keeping a constant edge-to-edge distance of 150 μm between the circular emitters. The FEA with a diameter of 50 μm and a pitch of 120 μm was found to be the best to achieve an emission current of 47 mA corresponding to an effective current density of 30.5 A/cm{sup 2} at 7 V/μm. The excellent emission current was attributed to good quality of CNT rooting into the substrate and optimized FEA structure, which provided a high electric field on a whole circular emitter of 50 μm and the best combination of the strong edge effect and CNT coverage. The experimental results were confirmed with computer simulation.« less

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

    PubMed

    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.

  18. Experimental measurement of the 4-d transverse phase space map of a heavy ion beam

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hopkins, H S

    1997-12-01

    The development and employment of a new diagnostic instrument for characterizing intense, heavy ion beams is reported on. This instrument, the ''Gated Beam Imager'' or ''GBI'' was designed for use on Lawrence Livermore National Laboratory Heavy Ion Fusion Project's ''Small Recirculator'', an integrated, scaled physics experiment and engineering development project for studying the transport and control of intense heavy ion beams as inertial fusion drivers in the production of electric power. The GBI allows rapid measurement and calculation of a heavy ion beam's characteristics to include all the first and second moments of the transverse phase space distribution, transverse emittance,more » envelope parameters and beam centroid. The GBI, with appropriate gating produces a time history of the beam resulting in a 4-D phase-space and time ''map'' of the beam. A unique capability of the GBI over existing diagnostic instruments is its ability to measure the ''cross'' moments between the two transverse orthogonal directions. Non-zero ''cross'' moments in the alternating gradient lattice of the Small Recirculator are indicative of focusing element rotational misalignments contributing to beam emittance growth. This emittance growth, while having the same effect on the ability to focus a beam as emittance growth caused by non-linear effects, is in principle removable by an appropriate number of focusing elements. The instrument uses the pepperpot method of introducing a plate with many pinholes into the beam and observing the images of the resulting beamlets as they interact with a detector after an appropriate drift distance. In order to produce adequate optical signal and repeatability, the detector was chosen to be a microchannel plate (MCP) with a phosphor readout screen. The heavy ions in the pepperpot beamlets are stopped in the MCP's thin front metal anode and the resulting secondary electron signal is amplified and proximity-focused onto the phosphor while maintaining the spatial and intensity characteristics of the heavy ion beamlets. The MCP used in this manner is a sensitive, accurate, and long-lasting detector, resistant against signal degradation experienced by previous methods of intense heavy ion beam detection and imaging. The performance of the GBI was benchmarked against existing mechanical emittance diagnostics and the results of sophisticated beam transport numerical simulation codes to demonstrate its usefulness as a diagnostic tool. A method of beam correction to remove the effects of quadrupole focusing element rotational misalignments is proposed using data obtainable from a GBI. An optimizing code was written to determine the parameters of the correction system elements based on input from the GBI. The results of this code for the Small Recirculator beam are reported on.« less

  19. MIRAGE: developments in IRSP systems, RIIC design, emitter fabrication, and performance

    NASA Astrophysics Data System (ADS)

    Bryant, Paul; Oleson, Jim; James, Jay; McHugh, Steve; Lannon, John; Vellenga, David; Goodwin, Scott; Huffman, Alan; Solomon, Steve; Goldsmith, George C., II

    2005-05-01

    SBIR's family of MIRAGE infrared scene projection systems is undergoing significant growth and expansion. The first two lots of production IR emitters have completed fabrication at Microelectronics Center of North Carolina/Research and Development Institute (MCNC-RDI), and the next round(s) of emitter production has begun. These latest emitter arrays support programs such as Large Format Resistive Array (LFRA), Optimized Array for Space-based Infrared Simulation (OASIS), MIRAGE 1.5, and MIRAGE II. We present the latest performance data on emitters fabricated at MCNC-RDI, plus integrated system performance on recently completed IRSP systems. Teamed with FLIR Systems/Indigo Operations, SBIR and the Tri-Services IRSP Working Group have completed development of the CMOS Read-In Integrated Circuit (RIIC) portion of the Wide Format Resistive Array (WFRA) program-to extend LFRA performance to a 768 x 1536 "wide screen" projection configuration. WFRA RIIC architecture and performance is presented. Finally, we summarize development of the LFRA Digital Emitter Engine (DEE) and OASIS cryogenic package assemblies, the next-generation Command & Control Electronics (C&CE).

  20. Fluorescence enhancement and strong-coupling in faceted plasmonic nanocavities

    NASA Astrophysics Data System (ADS)

    Kongsuwan, Nuttawut; Demetriadou, Angela; Chikkaraddy, Rohit; Baumberg, Jeremy J.; Hess, Ortwin

    2018-06-01

    Emission properties of a quantum emitter can be significantly modified inside nanometre-sized gaps between two plasmonic nanostructures. This forms a nanoscopic optical cavity which allows single-molecule detection and single-molecule strong-coupling at room temperature. However, plasmonic resonances of a plasmonic nanocavity are highly sensitive to the exact gap morphology. In this article, we shed light on the effect of gap morphology on the plasmonic resonances of a faceted nanoparticle-on-mirror (NPoM) nanocavity and their interaction with quantum emitters. We find that with increasing facet width the NPoM nanocavity provides weaker field enhancement and thus less coupling strength to a single quantum emitter since the effective mode volume increases with the facet width. However, if multiple emitters are present, a faceted NPoM nanocavity is capable of accommodating a larger number of emitters, and hence the overall coupling strength is larger due to the collective and coherent energy exchange from all the emitters. Our findings pave the way to more efficient designs of nanocavities for room-temperature light-matter strong-coupling, thus providing a big step forward to a non-cryogenic platform for quantum technologies.

  1. Diamond-based single-photon emitters

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

    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.

  2. Distinguishing triplet energy transfer and trap-assisted recombination in multi-color organic light-emitting diode with an ultrathin phosphorescent emissive layer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xue, Qin, E-mail: xueqin19851202@163.com; Liu, Shouyin; Xie, Guohua

    2014-03-21

    An ultrathin layer of deep-red phosphorescent emitter tris(1-phenylisoquinoline) iridium (III) (Ir(piq){sub 3}) is inserted within different positions of the electron blocking layer fac-tris (1-phenylpyrazolato-N,C{sup 2′})-iridium(III) (Ir(ppz){sub 3}) to distinguish the contribution of the emission from the triplet exciton energy transfer/diffusion from the adjacent blue phosphorescent emitter and the trap-assisted recombination from the narrow band-gap emitter itself. The charge trapping effect of the narrow band-gap deep-red emitter which forms a quantum-well-like structure also plays a role in shaping the electroluminescent characteristics of multi-color organic light-emitting diodes. By accurately controlling the position of the ultrathin sensing layer, it is considerably easy tomore » balance the white emission which is quite challenging for full-color devices with multiple emission zones. There is nearly no energy transfer detectable if 7 nm thick Ir(ppz){sub 3} is inserted between the blue phosphorescent emitter and the ultrathin red emitter.« less

  3. Fabrication and life testing of thermionic converters

    NASA Technical Reports Server (NTRS)

    Yang, L.; Bruce, R.

    1973-01-01

    An unfueled converter containing a chloride-fluoride duplex tungsten emitter of 4.78 eV vacuum work function was tested for 46,647 hours at an emitter temperature of 1973 K and an electrode power output of about 8 watts/sq cm. The test demonstrated the superior and stable performance of the (110) oriented tungsten emitter at high temperatures. Three 90 UC-10 ZrC(C/U = 1.04, tungsten additive = 4 wt %) fueled converters were fabricated and tested at an emitter temperature of 1873 K. Converter containing chloride-arc-cast duplex tungsten cladding showed temperature thermionic performance and slower rate of performance drop than converter containing chloride-fluoride duplex tungsten cladding. This is believed to be due to the superior fuel component diffusion resistance of the arc-cast tungsten substrate used in the fuel cladding. It was shown that a converter containing a carbide fueled chloride-arc-cast duplex tungsten emitter with an initial electrode power output of 6.80 watts/sq cm could still deliver an electrode power output of 6.16 watts/sq cm after 18,632 hours of operation at an emitter temperature of 1873 K.

  4. Thermographic Microstructure Monitoring in Electron Beam Additive Manufacturing.

    PubMed

    Raplee, J; Plotkowski, A; Kirka, M M; Dinwiddie, R; Okello, A; Dehoff, R R; Babu, S S

    2017-03-03

    To reduce the uncertainty of build performance in metal additive manufacturing, robust process monitoring systems that can detect imperfections and improve repeatability are desired. One of the most promising methods for in situ monitoring is thermographic imaging. However, there is a challenge in using this technology due to the difference in surface emittance between the metal powder and solidified part being observed that affects the accuracy of the temperature data collected. The purpose of the present study was to develop a method for properly calibrating temperature profiles from thermographic data to account for this emittance change and to determine important characteristics of the build through additional processing. The thermographic data was analyzed to identify the transition of material from metal powder to a solid as-printed part. A corrected temperature profile was then assembled for each point using calibrations for these surface conditions. Using this data, the thermal gradient and solid-liquid interface velocity were approximated and correlated to experimentally observed microstructural variation within the part. This work shows that by using a method of process monitoring, repeatability of a build could be monitored specifically in relation to microstructure control.

  5. Dual function conducting polymer diodes

    DOEpatents

    Heeger, Alan J.; Yu, Gang

    1996-01-01

    Dual function diodes based on conjugated organic polymer active layers are disclosed. When positively biased the diodes function as light emitters. When negatively biased they are highly efficient photodiodes. Methods of preparation and use of these diodes in displays and input/output devices are also disclosed.

  6. Experimental Realization of Efficient, Room Temperature Single-Photon Sources with Definite Circular and Linear Polarizations

    NASA Astrophysics Data System (ADS)

    Boutsidis, Christos

    In this thesis I present experimental demonstrations of room-temperature, single-photon sources with definite linear and circular polarizations. Definite photon polarization increases the efficiency of quantum communication systems. In contrast with cryogenic-temperature single-photon sources based on epitaxial quantum dots requiring expensive MBE and nanofabrication, my method utilizes a mature liquid crystal technology, which I made consistent with single-emitter fluorescence microscopy. The structures I have prepared are planar-aligned cholesteric liquid crystals forming 1-D photonic bandgaps for circularly-polarized light, which were used to achieve definite circularly-polarized fluorescence of single emitters doped in this environment. I also used planar-aligned nematic liquid crystals to align single molecules with linear dipole moments and achieved definite linearly-polarized fluorescence. I used single nanocrystal quantum dots, single nanodiamond color-centers, rare-earth-doped nanocrystals, and single terrylene and DiIC18(3) dye molecules as emitters. For nanocrystal quantum dots I observed circular polarization dissymmetry factors as large as ge = --1.6. In addition, I observed circularly-polarized resonances in the fluorescence of emitters within a cholesteric microcavity, with cavity quality factors of up to Q ˜ 250. I also showed that the fluorescence of DiIC18(3) dye molecules in planar-aligned nematic cells exhibits definite linear polarization, with a degree of polarization of rho = --0.58 +/- 0.03. Distributed Bragg reflectors form another type of microcavity that can be used to realize a single-photon source. I characterized the fluorescence from nanocrystal quantum dots doped in the defect layers of such microcavites, both organic and inorganic. Finally, to demonstrate the single-photon properties of single-emitter-doped cholesteric and nematic liquid crystal structures and distributed Bragg reflector microcavities, I present observations of photon antibunching from emitters doped in each of these structures. These experimental observations include photon antibunching from: nanocrystal quantum dots and nanodiamond color-centers doped in a cholesteric microcavity; terrylene and DiIC 18(3) dye molecules doped in nematic structures, and nanocrystal quantum dots doped in the distributed Bragg reflector microcavity. A value of the zero-time second-order coherence as low as g(2)(0) = 0.001 +/- 0.03 was measured. These results represent an important step forward in the realization of room temperature single-photon sources with definite polarization for secure quantum communication.

  7. Nanobubble induced formation of quantum emitters in monolayer semiconductors

    NASA Astrophysics Data System (ADS)

    Shepard, Gabriella D.; Ajayi, Obafunso A.; Li, Xiangzhi; Zhu, X.-Y.; Hone, James; Strauf, Stefan

    2017-06-01

    The recent discovery of exciton quantum emitters in transition metal dichalcogenides (TMDCs) has triggered renewed interest of localized excitons in low-dimensional systems. Open questions remain about the microscopic origin previously attributed to dopants and/or defects as well as strain potentials. Here we show that the quantum emitters can be deliberately induced by nanobubble formation in WSe2 and BN/WSe2 heterostructures. Correlations of atomic-force microscope and hyperspectral photoluminescence images reveal that the origin of quantum emitters and trion disorder is extrinsic and related to 10 nm tall nanobubbles and 70 nm tall wrinkles, respectively. We further demonstrate that ‘hot stamping’ results in the absence of 0D quantum emitters and trion disorder. The demonstrated technique is useful for advances in nanolasers and deterministic formation of cavity-QED systems in monolayer materials.

  8. Tuning the spectral emittance of α-SiC open-cell foams up to 1300 K with their macro porosity

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rousseau, B., E-mail: benoit.rousseau@univ-nantes.fr; Guevelou, S.; Mekeze-Monthe, A.

    2016-06-15

    A simple and robust analytical model is used to finely predict the spectral emittance under air up to 1300 K of α-SiC open-cell foams constituted of optically thick struts. The model integrates both the chemical composition and the macro-porosity and is valid only if foams have volumes higher than their Representative Elementary Volumes required for determining their emittance. Infrared emission spectroscopy carried out on a doped silicon carbide single crystal associated to homemade numerical tools based on 3D meshed images (Monte Carlo Ray Tracing code, foam generator) make possible to understand the exact role of the cell network in emittance.more » Finally, one can tune the spectral emittance of α-SiC foams up to 1300 K by simply changing their porosity.« less

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Astrelin, V. T., E-mail: V.T.Astrelin@inp.nsk.su; Kotelnikov, I. A.

    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 surfacemore » that are required for operation of the high-current optics module in numerical codes used to simulate charged particle sources is formulated.« less

  10. Non-blinking single-photon emitters in silica

    DOE PAGES

    Rabouw, Freddy T.; Cogan, Nicole M. B.; Berends, Anne C.; ...

    2016-02-19

    Samples for single-emitter spectroscopy are usually prepared by spin-coating a dilute solution of emitters on a microscope cover slip of silicate based glass (such as quartz). Here, we show that both borosilicate glass and quartz contain intrinsic defect colour centres that fluoresce when excited at 532 nm. In a microscope image the defect emission is indistinguishable from spin-coated emitters. The emission spectrum is characterised by multiple peaks with the main peak between 2.05 and 2.20 eV, most likely due to coupling to a silica vibration with an energy that varies between 160 and 180 meV. The defects are single-photon emitters,more » do not blink, and have photoluminescence lifetimes of a few nanoseconds. Furthermore, photoluminescence from such defects may previously have been misinterpreted as originating from single nanocrystal quantum dots.« less

  11. Emittance Growth in the DARHT-II Linear Induction Accelerator

    DOE PAGES

    Ekdahl, Carl; Carlson, Carl A.; Frayer, Daniel K.; ...

    2017-10-03

    The dual-axis radiographic hydrodynamic test (DARHT) facility uses bremsstrahlung radiation source spots produced by the focused electron beams from two linear induction accelerators (LIAs) to radiograph large hydrodynamic experiments driven by high explosives. Radiographic resolution is determined by the size of the source spot, and beam emittance is the ultimate limitation to spot size. On the DARHT-II LIA, we measure an emittance higher than predicted by theoretical simulations, and even though this accelerator produces submillimeter source spots, we are exploring ways to improve the emittance. Some of the possible causes for the discrepancy have been investigated using particle-in-cell codes. Finally,more » the simulations establish that the most likely source of emittance growth is a mismatch of the beam to the magnetic transport, which can cause beam halo.« less

  12. Emittance Growth in the DARHT-II Linear Induction Accelerator

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ekdahl, Carl; Carlson, Carl A.; Frayer, Daniel K.

    The dual-axis radiographic hydrodynamic test (DARHT) facility uses bremsstrahlung radiation source spots produced by the focused electron beams from two linear induction accelerators (LIAs) to radiograph large hydrodynamic experiments driven by high explosives. Radiographic resolution is determined by the size of the source spot, and beam emittance is the ultimate limitation to spot size. On the DARHT-II LIA, we measure an emittance higher than predicted by theoretical simulations, and even though this accelerator produces submillimeter source spots, we are exploring ways to improve the emittance. Some of the possible causes for the discrepancy have been investigated using particle-in-cell codes. Finally,more » the simulations establish that the most likely source of emittance growth is a mismatch of the beam to the magnetic transport, which can cause beam halo.« less

  13. Development of a pepper-pot device to determine the emittance of an ion beam generated by electron cyclotron resonance ion sources

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Strohmeier, M.; University of Applied Sciences Karlsruhe, Moltkestr. 30, 76133 Karlsruhe; Benitez, J. Y.

    2010-02-15

    This paper describes the recent development and commissioning of a pepper-pot emittance meter at the Lawrence Berkeley National Laboratory (LBNL). It is based on a potassium bromide (KBr) scintillator screen in combination with a charged coupled device camera. Pepper-pot scanners record the full four-dimensional transverse phase space emittances which are particularly interesting for electron cyclotron resonance ion sources. The strengths and limitations of evaluating emittances using optical pepper-pot scanners are described and systematic errors induced by the optical data acquisition system will be presented. Light yield tests of KBr exposed to different ion species and first emittance measurement data usingmore » ion beams extracted from the 6.4 GHz LBNL electron cyclotron resonance ion source are presented and discussed.« less

  14. Application of CTLM method combining interfacial structure characterization to investigate contact formation of silver paste metallization on crystalline silicon solar cells

    NASA Astrophysics Data System (ADS)

    Xiong, Shenghu; Yuan, Xiao; Tong, Hua; Yang, Yunxia; Liu, Cui; Ye, Xiaojun; Li, Yongsheng; Wang, Xianhao; Luo, Lan

    2018-04-01

    Circular transmission line model (CTLM) measurements were applied to study the contact formation mechanism of the silver paste metallization on n-type emitter of crystalline silicon solar cells. The electrical performance parameters ρc,Rsk , and Lt , which are related to the physical and chemical states of the multiphase materials at the interface, were extracted from the CTLM measurements, and were found to be sensitive to sintering temperature. As the temperature increased from 585 °C to 780 °C, initially the ρc value decreased rapidly, then flattened out and increased slightly. The order of resistivity magnitude was restricted by the SiNx passivation layer in the early sintering stages, and relied on the carrier tunneling probability affected by the precipitated silver crystallites or colloids, emitter doping concentration and molten glass layer. Based on the calculations that the sheet resistance underneath the electrode was reduced form 110 Ω / □ to 0.186 Ω / □ , it could be inferred that there was formation of a highly conductive layer of silver crystallites and colloids contained glass on the emitter. The transfer length Lt exhibited a U-shaped variation along with the temperature, reflecting the variation of the interfacial electrical properties. Overall, this article shows that the CTLM method can become a new powerful tool for researchers to meet the challenges of silver paste metallization innovation for manufacturing high-efficiency silicon solar cells.

  15. Nuclear reactor with internal thimble-type delayed neutron detection system

    DOEpatents

    Gross, Kenny C.; Poloncsik, John; Lambert, John D. B.

    1990-01-01

    This invention teaches improved apparatus for the method of detecting a breach in cladded fuel used in a nuclear reactor. The detector apparatus is located in the primary heat exchanger which conveys part of the reactor coolant past at least three separate delayed-neutron detectors mounted in this heat exchanger. The detectors are spaced apart such that the coolant flow time from the core to each detector is different, and these differences are known. The delayed-neutron activity at the detectors is a function of the delay time after the reaction in the fuel until the coolant carrying the delayed-neutron emitter passes the respective detector. This time delay is broken down into separate components including an isotopic holdup time required for the emitter to move through the fuel from the reaction to the coolant at the breach, and two transit times required for the emitter now in the coolant to flow from the breach to the detector loop and then via the loop to the detector. At least two of these time components are determined during calibrated operation of the reactor. Thereafter during normal reactor operation, repeated comparisons are made by the method of regression approximation of the third time component for the best-fit line correlating measured delayed-neutron activity against activity that is approximated according to specific equations. The equations use these time-delay components and known parameter values of the fuel and of the part and emitting daughter isotopes.

  16. Cooperative Effects in Closely Packed Quantum Emitters with Collective Dephasing

    NASA Astrophysics Data System (ADS)

    Prasanna Venkatesh, B.; Juan, M. L.; Romero-Isart, O.

    2018-01-01

    In a closely packed ensemble of quantum emitters, cooperative effects are typically suppressed due to the dephasing induced by the dipole-dipole interactions. Here, we show that by adding sufficiently strong collective dephasing, cooperative effects can be restored. Specifically, we show that the dipole force on a closely packed ensemble of strongly driven two-level quantum emitters, which collectively dephase, is enhanced in comparison to the dipole force on an independent noninteracting ensemble. Our results are relevant to solid-state systems with embedded quantum emitters such as color centers in diamond and superconducting qubits in microwave cavities and waveguides.

  17. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Halavanau, A.; Hyun, J.; Mihalcea, D.

    A photocathode, immersed in solenoidal magnetic field, can produce canonical-angular-momentum (CAM) dominated or “magnetized” electron beams. Such beams have an application in electron cooling of hadron beams and can also be uncoupled to yield asymmetric-emittance (“flat”) beams. In the present paper we explore the possibilities of the flat beam generation at Fermilab’s Accelerator Science and Technology (FAST) facility. We present optimization of the beam flatness and four-dimensional transverse emittance and investigate the mapping and its limitations of the produced eigen-emittances to conventional emittances using a skew-quadrupole channel. Possible application of flat beams at the FAST facility are also discussed.

  18. Electron emission from ferroelectrics - a review

    NASA Astrophysics Data System (ADS)

    Riege, H.

    1994-02-01

    The strong pulsed emission of electrons from the surface of ferroelectric (FE) materials was discovered at CERN in 1987. Since then many aspects and properties of the method of generation and propagation of electron beams from FE have been studied experimentally. The method is based on macroscopic charge separation and self-emission of electrons under the influence of their own space-charge fields. Hence, this type of emission is not limited by the Langmuir-Child law as are conventional emission methods. Charge separation and electron emission can be achieved by rapid switching of the spontaneous, ferroelectric polarization. Polarization switching may be induced by application of electrical-field or mechanical-pressure pulses, as well as by thermal heating or laser illumination of the ferroelectric emitter. At higher emission intensities plasma formation assists the FE emission and leads to a strong growth of emitted current amplitude, which is no longer limited by the FE material and the surface properties. The most attractive features of FE emission are robustness and ease of manipulation of the emitter cathodes which can be transported through atmospheric air and used without any problems in vacuum, low-pressure gas or plasma environments. Large-area arrangements of multiple emitters, switched in interleaved mode, can produce electron beams of any shape, current amplitude or time structure. The successful application of FE emission in accelerator technology has been demonstrated experimentally in several cases, e.g. for triggering high-power gas switches, for photocathodes in electron guns, and for electron-beam generators intended to generate, neutralize and enhance ion beams in ion sources and ion linacs. Other applications can be envisaged in microwave power generators and in the fields of electronics and vacuum microelectronics.

  19. Implementation and validation of collapsed cone superposition for radiopharmaceutical dosimetry of photon emitters

    NASA Astrophysics Data System (ADS)

    Sanchez-Garcia, Manuel; Gardin, Isabelle; Lebtahi, Rachida; Dieudonné, Arnaud

    2015-10-01

    Two collapsed cone (CC) superposition algorithms have been implemented for radiopharmaceutical dosimetry of photon emitters. The straight CC (SCC) superposition method uses a water energy deposition kernel (EDKw) for each electron, positron and photon components, while the primary and scatter CC (PSCC) superposition method uses different EDKw for primary and once-scattered photons. PSCC was implemented only for photons originating from the nucleus, precluding its application to positron emitters. EDKw are linearly scaled by radiological distance, taking into account tissue density heterogeneities. The implementation was tested on 100, 300 and 600 keV mono-energetic photons and 18F, 99mTc, 131I and 177Lu. The kernels were generated using the Monte Carlo codes MCNP and EGSnrc. The validation was performed on 6 phantoms representing interfaces between soft-tissues, lung and bone. The figures of merit were γ (3%, 3 mm) and γ (5%, 5 mm) criterions corresponding to the computation comparison on 80 absorbed doses (AD) points per phantom between Monte Carlo simulations and CC algorithms. PSCC gave better results than SCC for the lowest photon energy (100 keV). For the 3 isotopes computed with PSCC, the percentage of AD points satisfying the γ (5%, 5 mm) criterion was always over 99%. A still good but worse result was found with SCC, since at least 97% of AD-values verified the γ (5%, 5 mm) criterion, except a value of 57% for the 99mTc with the lung/bone interface. The CC superposition method for radiopharmaceutical dosimetry is a good alternative to Monte Carlo simulations while reducing computation complexity.

  20. Implementation and validation of collapsed cone superposition for radiopharmaceutical dosimetry of photon emitters.

    PubMed

    Sanchez-Garcia, Manuel; Gardin, Isabelle; Lebtahi, Rachida; Dieudonné, Arnaud

    2015-10-21

    Two collapsed cone (CC) superposition algorithms have been implemented for radiopharmaceutical dosimetry of photon emitters. The straight CC (SCC) superposition method uses a water energy deposition kernel (EDKw) for each electron, positron and photon components, while the primary and scatter CC (PSCC) superposition method uses different EDKw for primary and once-scattered photons. PSCC was implemented only for photons originating from the nucleus, precluding its application to positron emitters. EDKw are linearly scaled by radiological distance, taking into account tissue density heterogeneities. The implementation was tested on 100, 300 and 600 keV mono-energetic photons and (18)F, (99m)Tc, (131)I and (177)Lu. The kernels were generated using the Monte Carlo codes MCNP and EGSnrc. The validation was performed on 6 phantoms representing interfaces between soft-tissues, lung and bone. The figures of merit were γ (3%, 3 mm) and γ (5%, 5 mm) criterions corresponding to the computation comparison on 80 absorbed doses (AD) points per phantom between Monte Carlo simulations and CC algorithms. PSCC gave better results than SCC for the lowest photon energy (100 keV). For the 3 isotopes computed with PSCC, the percentage of AD points satisfying the γ (5%, 5 mm) criterion was always over 99%. A still good but worse result was found with SCC, since at least 97% of AD-values verified the γ (5%, 5 mm) criterion, except a value of 57% for the (99m)Tc with the lung/bone interface. The CC superposition method for radiopharmaceutical dosimetry is a good alternative to Monte Carlo simulations while reducing computation complexity.

  1. Dynamic radioactive particle source

    DOEpatents

    Moore, Murray E; Gauss, Adam Benjamin; Justus, Alan Lawrence

    2012-06-26

    A method and apparatus for providing a timed, synchronized dynamic alpha or beta particle source for testing the response of continuous air monitors (CAMs) for airborne alpha or beta emitters is provided. The method includes providing a radioactive source; placing the radioactive source inside the detection volume of a CAM; and introducing an alpha or beta-emitting isotope while the CAM is in a normal functioning mode.

  2. Efficient Generation of an Array of Single Silicon-Vacancy Defects in Silicon Carbide

    NASA Astrophysics Data System (ADS)

    Wang, Junfeng; Zhou, Yu; Zhang, Xiaoming; Liu, Fucai; Li, Yan; Li, Ke; Liu, Zheng; Wang, Guanzhong; Gao, Weibo

    2017-06-01

    Color centers in silicon carbide have increasingly attracted attention in recent years owing to their excellent properties such as single-photon emission, good photostability, and long spin-coherence time even at room temperature. As compared to diamond, which is widely used for hosting nitrogen-vacancy centers, silicon carbide has an advantage in terms of large-scale, high-quality, and low-cost growth, as well as an advanced fabrication technique in optoelectronics, leading to prospects for large-scale quantum engineering. In this paper, we report an experimental demonstration of the generation of a single-photon-emitter array through ion implantation. VSi defects are generated in predetermined locations with high generation efficiency (approximately 19 % ±4 % ). The single emitter probability reaches approximately 34 % ±4 % when the ion-implantation dose is properly set. This method serves as a critical step in integrating single VSi defect emitters with photonic structures, which, in turn, can improve the emission and collection efficiency of VSi defects when they are used in a spin photonic quantum network. On the other hand, the defects are shallow, and they are generated about 40 nm below the surface which can serve as a critical resource in quantum-sensing applications.

  3. Characterization of sputter deposited thin film scandate cathodes for miniaturized thermionic converter applications

    NASA Astrophysics Data System (ADS)

    Zavadil, Kevin R.; Ruffner, Judith H.; King, Donald B.

    1999-01-01

    We have successfully developed a method for fabricating scandate-based thermionic emitters in thin film form. The primary goal of our effort is to develop thin film emitters that exhibit low work function, high intrinsic electron emissivity, minimum thermal activation properties and that can be readily incorporated into a microgap converter. Our approach has been to incorporate BaSrO into a Sc2O3 matrix using rf sputtering to produce thin films. Diode testing has shown the resulting films to be electron emissive at temperatures as low as 900 K with current densities of 0.1 mA.cm-2 at 1100 K and saturation voltages. We calculate an approximate maximum work function of 1.8 eV and an apparent emission constant (Richardson's constant, A*) of 36 mA.cm-2.K-2. Film compositional and structural analysis shows that a significant surface and subsurface alkaline earth hydroxide phase can form and probably explains the limited utilization and stability of Ba and its surface complexes. The flexibility inherent in sputter deposition suggests alternate strategies for eliminating undesirable phases and optimizing thin film emitter properties.

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

    PubMed

    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.

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

    PubMed Central

    Sherwin, Tyrone; Easte, Mikala; Wang, Kevin I-Kai; Dai, Wenbin

    2018-01-01

    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. PMID:29443906

  6. A system for measuring bubble voidage and frequency around tubes immersed in a fluidized bed of particles

    NASA Astrophysics Data System (ADS)

    Whitty, Kevin J.; Siddoway, Michael

    2010-07-01

    Gas-solid fluidized beds are common in chemical processing and energy production industries. These types of reactors frequently have banks of tubes immersed within the bed to provide heating or cooling, and it is important that the fluid dynamics within these bundles is efficient and uniform. This paper presents a simple, low-cost method for quantitatively analyzing the behavior of gas bubbles within banks of tubes in a fluidized bed cold flow model. Two probes, one containing an infrared emitter and one containing an infrared (IR) detector, are placed into adjacent glass tubes such that the emitter and detector face each other. As bubbles pass through the IR beam, the detector signal increases due to less solid material blocking the path between the emitter and detector. By calibrating the signal response to known voidage of the material, one can measure the bubble voidage at various locations within the tube bundle. The rate and size of bubbles passing through the beam can also be determined by high frequency data collection and subsequent analysis. This technique allows one to develop a map of bubble voidage within a fluidized bed, which can be useful for model validation and system optimization.

  7. Parallel mapping of optical near-field interactions by molecular motor-driven quantum dots.

    PubMed

    Groß, Heiko; Heil, Hannah S; Ehrig, Jens; Schwarz, Friedrich W; Hecht, Bert; Diez, Stefan

    2018-04-30

    In the vicinity of metallic nanostructures, absorption and emission rates of optical emitters can be modulated by several orders of magnitude 1,2 . Control of such near-field light-matter interaction is essential for applications in biosensing 3 , light harvesting 4 and quantum communication 5,6 and requires precise mapping of optical near-field interactions, for which single-emitter probes are promising candidates 7-11 . However, currently available techniques are limited in terms of throughput, resolution and/or non-invasiveness. Here, we present an approach for the parallel mapping of optical near-field interactions with a resolution of <5 nm using surface-bound motor proteins to transport microtubules carrying single emitters (quantum dots). The deterministic motion of the quantum dots allows for the interpolation of their tracked positions, resulting in an increased spatial resolution and a suppression of localization artefacts. We apply this method to map the near-field distribution of nanoslits engraved into gold layers and find an excellent agreement with finite-difference time-domain simulations. Our technique can be readily applied to a variety of surfaces for scalable, nanometre-resolved and artefact-free near-field mapping using conventional wide-field microscopes.

  8. Vacancy-impurity centers in diamond: prospects for synthesis and applications

    NASA Astrophysics Data System (ADS)

    Ekimov, E. A.; Kondrin, M. V.

    2017-06-01

    The bright luminescence of impurity-vacancy complexes, combined with high chemical and radiation resistance, makes diamond an attractive platform for the production of single-photon emitters and luminescent biomarkers for applications in nanoelectronics and medicine. Two representatives of this kind of defects in diamond, silicon-vacancy (SiV) and germanium-vacancy (GeV) centers, are discussed in this review; their similarities and differences are demonstrated in terms of the more thoroughly studied nitrogen-vacancy (NV) complexes. The recent discovery of GeV luminescent centers opens a unique opportunity for the controlled synthesis of single-photon emitters in nanodiamonds. We demonstrate prospects for the high-pressure high-temperature (HPHT) technique to create single-photon emitters, not only as an auxiliary to chemical vapor deposition (CVD) and ion-implantation methods but also as a primary synthesis tool for producing color centers in nanodiamonds. Besides practical applications, comparative studies of these two complexes, which belong to the same structural class of defects, have a fundamental importance for deeper understanding of shelving levels, the electronic structure, and optical properties of these centers. In conclusion, we discuss several open problems regarding the structure, charge state, and practical application of these centers, which still require a solution.

  9. A system for measuring bubble voidage and frequency around tubes immersed in a fluidized bed of particles.

    PubMed

    Whitty, Kevin J; Siddoway, Michael

    2010-07-01

    Gas-solid fluidized beds are common in chemical processing and energy production industries. These types of reactors frequently have banks of tubes immersed within the bed to provide heating or cooling, and it is important that the fluid dynamics within these bundles is efficient and uniform. This paper presents a simple, low-cost method for quantitatively analyzing the behavior of gas bubbles within banks of tubes in a fluidized bed cold flow model. Two probes, one containing an infrared emitter and one containing an infrared (IR) detector, are placed into adjacent glass tubes such that the emitter and detector face each other. As bubbles pass through the IR beam, the detector signal increases due to less solid material blocking the path between the emitter and detector. By calibrating the signal response to known voidage of the material, one can measure the bubble voidage at various locations within the tube bundle. The rate and size of bubbles passing through the beam can also be determined by high frequency data collection and subsequent analysis. This technique allows one to develop a map of bubble voidage within a fluidized bed, which can be useful for model validation and system optimization.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kyritsakis, A., E-mail: akyritsos1@gmail.com; Xanthakis, J. P.

    2016-01-28

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

  11. Continuous-wave mid-infrared photonic crystal light emitters at room temperature

    NASA Astrophysics Data System (ADS)

    Weng, Binbin; Qiu, Jijun; Shi, Zhisheng

    2017-01-01

    Mid-infrared photonic crystal enhanced lead-salt light emitters operating under continuous-wave mode at room temperature were investigated in this work. For the device, an active region consisting of 9 pairs of PbSe/Pb0.96Sr0.04Se quantum wells was grown by molecular beam epitaxy method on top of a Si(111) substrate which was initially dry-etched with a two-dimensional photonic crystal structure in a pattern of hexagonal holes. Because of the photonic crystal structure, an optical band gap between 3.49 and 3.58 µm was formed, which matched with the light emission spectrum of the quantum wells at room temperature. As a result, under optical pumping, using a near-infrared continuous-wave semiconductor laser, the device exhibited strong photonic crystal band-edge mode emissions and delivered over 26.5 times higher emission efficiency compared to the one without photonic crystal structure. The output power obtained was up to 7.68 mW (the corresponding power density was 363 mW/cm2), and a maximum quantum efficiency reached to 1.2%. Such photonic crystal emitters can be used as promising light sources for novel miniaturized gas-sensing systems.

  12. Electromagnetic compatibility of implantable neurostimulators to RFID emitters.

    PubMed

    Pantchenko, Oxana S; Seidman, Seth J; Guag, Joshua W; Witters, Donald M; Sponberg, Curt L

    2011-06-09

    The objective of this study is to investigate electromagnetic compatibility (EMC) of implantable neurostimulators with the emissions from radio frequency identification (RFID) emitters. Six active implantable neurostimulators with lead systems were tested for susceptibility to electromagnetic fields generated by 22 RFID emitters. These medical devices have been approved for marketing in the U.S. for a number of intended uses that include: epilepsy, depression, incontinence, Parkinsonian tremor and pain relief. Each RFID emitter had one of the following carrier frequencies: 125 kHz, 134 kHz, 13.56 MHz, 433 MHz, 915 MHz and 2.45 GHz. The test results showed the output of one of the implantable neurostimulators was inhibited by 134 kHz RFID emitter at separation distances of 10 cm or less. The output of the same implantable neurostimulator was also inhibited by another 134 kHz RFID emitter at separation distances of 10 cm or less and also showed inconsistent pulsing rate at a separation distance of 15 cm. Both effects occurred during and lasted through out the duration of the exposure. The clinical significance of the effects was assessed by a clinician at the U.S. Food and Drug Administration. The effects were determined to be clinically significant only if they occurred for extended period of time. There were no observed effects from the other 5 implantable neurostimulators or during exposures from other RFID emitters.

  13. Emittance measurements for optimum operation of the J-PARC RF-driven H{sup −} ion source

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ueno, A., E-mail: akira.ueno@j-parc.jp; Ohkoshi, K.; Ikegami, K.

    2015-04-08

    In order to satisfy the Japan Proton Accelerator Research Complex (J-PARC) second stage requirements of an H{sup −} ion beam of 60mA within normalized emittances of 1.5πmm•mrad both horizontally and vertically, a flat top beam duty factor of 1.25% (500μs×25Hz) and a life-time of longer than 1month, the J-PARC cesiated RF-driven H{sup −} ion source was developed by using an internal-antenna developed at the Spallation Neutron Source (SNS). The transverse emittances of the source were measured with various conditions to find out the optimum operation conditions minimizing the horizontal and vertical rms normalized emittances. The transverse emittances were most effectivelymore » reduced by operating the source with the plasma electrode temperature lower than 70°C. The optimum value of the cesium (Cs) density around the beam hole of the plasma electrode seems to be proportional to the plasma electrode temperature. The fine control of the Cs density is indispensable, since the emittances seem to increase proportionally to the excessiveness of the Cs density. Furthermore, the source should be operated with the Cs density beyond a threshold value, since the plasma meniscus shape and the ellipse parameters of the transverse emittances seem to be changed step-function-likely on the threshold Cs value.« less

  14. Improving low-level plasma protein mass spectrometry-based detection for candidate biomarker discovery and validation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Page, Jason S.; Kelly, Ryan T.; Camp, David G.

    2008-09-01

    Methods. To improve the detection of low abundance protein candidate biomarker discovery and validation, particularly in complex biological fluids such as blood plasma, increased sensitivity is desired using mass spectrometry (MS)-based instrumentation. A key current limitation on the sensitivity of electrospray ionization (ESI) MS is due to the fact that many sample molecules in solution are never ionized, and the vast majority of the ions that are created are lost during transmission from atmospheric pressure to the low pressure region of the mass analyzer. Two key technologies, multi-nanoelectrospray emitters and the electrodynamic ion funnel have recently been developed and refinedmore » at Pacific Northwest National Laboratory (PNNL) to greatly improve the ionization and transmission efficiency of ESI MS based analyses. Multi-emitter based ESI enables the flow from a single source (typically a liquid chromatography [LC] column) to be divided among an array of emitters (Figure 1). The flow rate delivered to each emitter is thus reduced, allowing the well-documented benefits of nanoelectrospray 1 for both sensitivity and quantitation to be realized for higher flow rate separations. To complement the increased ionization efficiency afforded by multi-ESI, tandem electrodynamic ion funnels have also been developed at PNNL, and shown to greatly improve ion transmission efficiency in the ion source interface.2, 3 These technologies have been integrated into a triple quadrupole mass spectrometer for multiple reaction monitoring (MRM) of probable biomarker candidates in blood plasma and show promise for the identification of new species even at low level concentrations.« less

  15. Emission enhancement, light extraction and carrier dynamics in InGaAs/GaAs nanowire arrays

    NASA Astrophysics Data System (ADS)

    Kivisaari, Pyry; Chen, Yang; Anttu, Nicklas

    2018-03-01

    Nanowires (NWs) have the potential for a wide range of new optoelectronic applications. For example, light-emitting diodes that span over the whole visible spectrum are currently being developed from NWs to overcome the well known green gap problem. However, due to their small size, NW devices exhibit special properties that complicate their analysis, characterization, and further development. In this paper, we develop a full optoelectronic simulation tool for NW array light emitters accounting for carrier transport and wave-optical emission enhancement (EE), and we use the model to simulate InGaAs/GaAs NW array light emitters with different geometries and temperatures. Our results show that NW arrays emit light preferentially to certain angles depending on the NW diameter and temperature, encouraging temperature- and angle-resolved measurements of NW array light emission. On the other hand, based on our results both the EE and light extraction efficiency can easily change by at least a factor of two between room temperature and 77 K, complicating the characterization of NW light emitters if conventional methods are used. Finally, simulations accounting for surface recombination emphasize its major effect on the device performance. For example, a surface recombination velocity of 104 cm s-1 reported earlier for bare InGaAs surfaces results in internal quantum efficiencies less than 30% for small-diameter NWs even at the temperature of 30 K. This highlights that core-shell structures or high-quality passivation techniques are eventually needed to achieve efficient NW-based light emitters.

  16. Low energy ion beam dynamics of NANOGAN ECR ion source

    NASA Astrophysics Data System (ADS)

    Kumar, Sarvesh; Mandal, A.

    2016-04-01

    A new low energy ion beam facility (LEIBF) has been developed for providing the mass analyzed highly charged intense ion beams of energy ranging from a few tens of keV to a few MeV for atomic, molecular and materials sciences research. The new facility consists of an all permanent magnet 10 GHz electron cyclotron resonance (ECR) ion source (NANOGAN) installed on a high voltage platform (400 kV) which provides large currents of multiply charged ion beams. Higher emittance at low energy of intense ion beam puts a tremendous challenge to the beam optical design of this facility. The beam line consists of mainly the electrostatic quadrupoles, an accelerating section, analyzing cum switching magnet and suitable beam diagnostics including vacuum components. The accelerated ion beam is analyzed for a particular mass to charge (m/q) ratio as well as guided to three different lines along 75°, 90° and 105° using a large acceptance analyzing cum switching magnet. The details of transverse beam optics to all the beam lines with TRANSPORT and GICOSY beam optics codes are being described. Field computation code, OPERA 3D has been utilized to design the magnets and electrostatic quadrupoles. A theoretical estimation of emittance for optimized geometry of ion source is given so as to form the basis of beam optics calculations. The method of quadrupole scan of the beam is used to characterize the emittance of the final beam on the target. The measured beam emittance increases with m/q ratios of various ion beams similar to the trend observed theoretically.

  17. An in-beam PET system for monitoring ion-beam therapy: test on phantoms using clinical 62 MeV protons

    NASA Astrophysics Data System (ADS)

    Camarlinghi, N.; Sportelli, G.; Battistoni, G.; Belcari, N.; Cecchetti, M.; Cirrone, G. A. P.; Cuttone, G.; Ferretti, S.; Kraan, A.; Retico, A.; Romano, F.; Sala, P.; Straub, K.; Tramontana, A.; Del Guerra, A.; Rosso, V.

    2014-04-01

    Ion therapy allows the delivery of highly conformal dose taking advantage of the sharp depth-dose distribution at the Bragg-peak. However, patient positioning errors and anatomical uncertainties can cause dose distortions. To exploit the full potential of ion therapy, an accurate monitoring system of the ion range is needed. Among the proposed methods to monitor the ion range, Positron Emission Tomography (PET) has proven to be the most mature technique, allowing to reconstruct the β+ activity generated in the patient by the nuclear interaction of the ions, that can be acquired during or after the treatment. Taking advantages of the spatial correlation between positron emitters created along the ions path and the dose distribution, it is possible to reconstruct the ion range. Due to the high single rates generated during the beam extraction, the acquisition of the β+ activity is typically performed after the irradiation (cyclotron) or in between the synchrotron spills. Indeed the single photon rate can be one or more orders of magnitude higher than normal for cyclotron. Therefore, acquiring the activity during the beam irradiation requires a detector with a very short dead time. In this work, the DoPET detector, capable of sustaining the high event rate generated during the cyclotron irradiation, is presented. The capability of the system to acquire data during and after the irradiation will be demonstrated by showing the reconstructed activity for different PMMA irradiations performed using clinical dose rates and the 62 MeV proton beam at the CATANA-LNS-INFN. The reconstructed activity widths will be compared with the results obtained by simulating the proton beam interaction with the FLUKA Monte Carlo. The presented data are in good agreement with the FLUKA Monte Carlo.

  18. Determining Directional Emittance With An Infrared Imager

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    Directional emittances of flat specimen of smooth-surfaced, electrically nonconductive material at various temperatures computed from measurements taken by infrared radiometric imager operating in conjunction with simple ancillary equipment. Directional emittances useful in extracting detailed variations of surface temperatures from infrared images of curved, complexly shaped other specimens of same material. Advantages: simplification of measurement procedure and reduction of cost.

  19. Simulation of Soil Wetting Patterns in Drip and Subsurface Irrigation. Effects in Design and Irrigation Management Variables.

    NASA Astrophysics Data System (ADS)

    Rodríguez-Sinobas, L.; Gil-Rodríguez, M.; Sánchez, R.; Losada, A.; Castañón, G.; Juana, L.; Laguna, F. V.; Benítez, J.

    2010-05-01

    Conventional drip irrigation is considered one of the most efficient irrigation systems. Alternatively to traditional surface drip irrigation systems (DI), laterals are deployed underneath the soil surface, as in subsurface drip irrigation (SDI), leading to a higher potential efficiency, which is of especial interest in places where water is a limited source. The design and management of DI and SDI systems involve selection of an appropriate combination of emitter discharge rate and spacing between emitters and the inlet pressure and irrigation time for any given set of soil, crop, and climatic conditions, as well as understanding the wetted zone pattern around the emitter. Likewise, water distribution is affected by soil hydraulic properties, initial water content, emitter discharge, irrigation frequency, evapotranspiration and root characteristics. However, complexity arousing of soil water properties and soil profile characteristics means that these are often not properly considered in the design and management of those systems. A better understanding of the infiltration process around the discharge point source should contribute to increase water use efficiency and thus to reduce the risk of environmental impact of irrigation. In this regard, numerical models have been proved to be a powerful tool to analyze the evolution of the wetting pattern during the distribution and redistribution processes, in order to explore irrigation management strategies, to set up the duration of irrigation, and finally to optimize water use efficiency. Also, irrigation design variables such as emitter spacing and discharge could also be assessed. In this study the suitability of the HYDRUS-2D to simulate infiltration process around an emitter during irrigation of a loamy soil with drip and SDI laterals has been addressed. The model was then applied in order to evaluate the main dimensions of the wetted soil volume surrounding the emitter during irrigation. Irrigation uniformity with DI and SDI laterals were determined by field evaluations at different inlet head pressures. Results were related with estimations made on water distribution within the soil that were simulated taking into account the emitter discharge at different lateral locations, initial soil water content, soil hydraulic properties and time of irrigation. Conclusions highlight the effect of emitter discharge, emitter spacing, and irrigation time on wetting patterns, and thus solute transport, in both drip and subsurface drip irrigation. The effect of emitter depth was also considered in SDI. Some recommendations for the design and management of these irrigation systems are also provided.

  20. A NOVEL TECHNIQUE FOR THE RAPID IDENTIFICATION OF ALPHA EMITTERS RELEASED DURING A RADIOLOGICAL INCIDENT.

    EPA Science Inventory

    Currently there are no standard radioanalytical methods applicable to the initial phase of a radiological emergency, for the early identification and quantification of alpha emitting radionuclides. Of particular interest are determinations of the presence and concentration of is...

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