WorldWideScience

Sample records for submillimeter wave transistors

  1. Submillimeter wave ESR of copper-oxides

    International Nuclear Information System (INIS)

    Ohta, Hitoshi; Motokawa, Mitsuhiro

    1993-01-01

    Since the discovery of high T c superconductors the magnetism of various copper-oxides has attracted much interest. Especially the magnetism of strong spin correlation systems in various CuO 4 networks is of great interest because it is well known that the superconductivity is occurring in the CuO 2 plane of the high T c superconductors. Here the authors will show some of their work done on copper-oxides by submillimeter wave ESR. The submillimeter wave ESR can provide the frequency region of 90 ∼ 3,100 GHz and the pulse magnetic field up to 30T

  2. Submillimeter wave propagation in tokamak plasmas

    International Nuclear Information System (INIS)

    Ma, C.H.; Hutchinson, D.P.; Staats, P.A.; Vander Sluis, K.L.; Mansfield, D.K.; Park, H.; Johnson, L.C.

    1985-01-01

    The propagation of submillimeter-waves (smm) in tokamak plasmas has been investigated both theoretically and experimentally to ensure successful measurements of electron density and plasma current distributions in tokamak devices. Theoretical analyses have been carried out to study the polarization of the smm waves in TFTR and ISX-B tokamaks. A multichord smm wave interferometer/polarimeter system has been employed to simultaneously measure the line electron density and poloidal field-induced Faraday rotation in the ISX-B tokamak. The experimental study on TFTR is under way. Computer codes have been developed and have been used to study the wave propagation and to reconstruct the distributions of plasma current and density from the measured data. The results are compared with other measurements

  3. Submillimeter wave propagation in tokamak plasmas

    International Nuclear Information System (INIS)

    Ma, C.H.; Hutchinson, D.P.; Staats, P.A.; Vander Sluis, K.L.; Mansfield, D.K.; Park, H.; Johnson, L.C.

    1986-01-01

    Propagation of submillimeter waves (smm) in tokamak plasma was investigated both theoretically and experimentally to ensure successful measurements of electron density and plasma current distributions in tokamak devices. Theoretical analyses were carried out to study the polarization of the smm waves in TFTR and ISX-B tokamaks. A multichord smm wave interferometer/polarimeter system was employed to simultaneously measure the line electron density and poloidal field-induced Faraday rotation in the ISX-B tokamak. The experimental study on TFTR is under way. Computer codes were developed and have been used to study the wave propagation and to reconstruct the distributions of plasma current and density from the measured data. The results are compared with other measurements. 5 references, 2 figures

  4. Cryogenic readout integrated circuits for submillimeter-wave camera

    International Nuclear Information System (INIS)

    Nagata, H.; Kobayashi, J.; Matsuo, H.; Akiba, M.; Fujiwara, M.

    2006-01-01

    The development of cryogenic readout circuits for Superconducting Tunneling Junction (Sj) direct detectors for submillimeter wave is presented. A SONY n-channel depletion-mode GaAs Junction Field Effect Transistor (JFET) is a candidate for circuit elements of the preamplifier. We measured electrical characteristics of the GaAs JFETs in the temperature range between 0.3 and 4.2K, and found that the GaAs JFETs work with low power consumption of a few microwatts, and show good current-voltage characteristics without cryogenic anomalies such as kink phenomena or hysteresis behaviors. Furthermore, measurements at 0.3K show that the input referred noise is as low as 0.6μV/Hz at 1Hz. Based on these results and noise calculations, we estimate that a Capacitive Transimpedance Amplifier with the GaAs JFETs will have low noise and STJ detectors will operate below background noise limit

  5. Cryogenic readout integrated circuits for submillimeter-wave camera

    Energy Technology Data Exchange (ETDEWEB)

    Nagata, H. [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan) and National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan)]. E-mail: hirohisa.nagata@nao.ac.jp; Kobayashi, J. [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); The Graduate University for Advanced Studies, Shonan Village, Hayama, Kanagawa 240-0193 (Japan); Matsuo, H. [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Akiba, M. [National Institute of Information and Communications Technology, Koganei, Tokyo 184-8795 (Japan); Fujiwara, M. [National Institute of Information and Communications Technology, Koganei, Tokyo 184-8795 (Japan)

    2006-04-15

    The development of cryogenic readout circuits for Superconducting Tunneling Junction (Sj) direct detectors for submillimeter wave is presented. A SONY n-channel depletion-mode GaAs Junction Field Effect Transistor (JFET) is a candidate for circuit elements of the preamplifier. We measured electrical characteristics of the GaAs JFETs in the temperature range between 0.3 and 4.2K, and found that the GaAs JFETs work with low power consumption of a few microwatts, and show good current-voltage characteristics without cryogenic anomalies such as kink phenomena or hysteresis behaviors. Furthermore, measurements at 0.3K show that the input referred noise is as low as 0.6{mu}V/Hz at 1Hz. Based on these results and noise calculations, we estimate that a Capacitive Transimpedance Amplifier with the GaAs JFETs will have low noise and STJ detectors will operate below background noise limit.

  6. Submillimeter Wave Antenna With Slow Wave Feed Line

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Krozer, Viktor; Kotiranta, Mikko

    2009-01-01

    Submillimeter wave radiation, which is also referred to as terahertz radiation, has not been extensively explored until recently due to a lack of reliable components and devices in this frequency range. Current advances in technology have made it possible to explore this portion of the electromag...

  7. Demonstration of a Submillimeter-Wave HEMT Oscillator Module at 330 GHz

    Science.gov (United States)

    Radisic, Vesna; Deal, W. R.; Mei, X. B.; Yoshida, Wayne; Liu, P. H.; Uyeda, Jansen; Lai, Richard; Samoska, Lorene; Fung, King Man; Gaier, Todd; hide

    2010-01-01

    In this work, radial transitions have been successfully mated with a HEMT-based MMIC (high-electron-mobility-transistor-based monolithic microwave integrated circuit) oscillator circuit. The chip has been assembled into a WR2.2 waveguide module for the basic implementation with radial E-plane probe transitions to convert the waveguide mode to the MMIC coplanar waveguide mode. The E-plane transitions have been directly integrated onto the InP substrate to couple the submillimeter-wave energy directly to the waveguides, thus avoiding wire-bonds in the RF path. The oscillator demonstrates a measured 1.7 percent DC-RF efficiency at the module level. The oscillator chip uses 35-nm-gate-length HEMT devices, which enable the high frequency of oscillation, creating the first demonstration of a packaged waveguide oscillator that operates over 300 GHz and is based on InP HEMT technology. The oscillator chip is extremely compact, with dimensions of only 1.085 x 320 sq mm for a total die size of 0.35 sq mm. This fully integrated, waveguide oscillator module, with an output power of 0.27 mW at 330 GHz, can provide low-mass, low DC-power-consumption alternatives to existing local oscillator schemes, which require high DC power consumption and large mass. This oscillator module can be easily integrated with mixers, multipliers, and amplifiers for building high-frequency transmit and receive systems at submillimeter wave frequencies. Because it requires only a DC bias to enable submillimeter wave output power, it is a simple and reliable technique for generating power at these frequencies. Future work will be directed to further improving the applicability of HEMT transistors to submillimeter wave and terahertz applications. Commercial applications include submillimeter-wave imaging systems for hidden weapons detection, airport security, homeland security, and portable low-mass, low-power imaging systems

  8. Three-Stage InP Submillimeter-Wave MMIC Amplifier

    Science.gov (United States)

    Pukala, David; Samoska, Lorene; Man, King; Gaier, Todd; Deal, William; Lai, Richard; Mei, Gerry; Makishi, Stella

    2008-01-01

    A submillimeter-wave monolithic integrated- circuit (S-MMIC) amplifier has been designed and fabricated using an indium phosphide (InP) 35-nm gate-length high electron mobility transistor (HEMT) device, developed at Northrop Grumman Corporation. The HEMT device employs two fingers each 15 micrometers wide. The HEMT wafers are grown by molecular beam epitaxy (MBE) and make use of a pseudomorphic In0.75Ga0.25As channel, a silicon delta-doping layer as the electron supply, an In0.52Al0.48As buffer layer, and an InP substrate. The three-stage design uses coplanar waveguide topology with a very narrow ground-to-ground spacing of 14 micrometers. Quarter-wave matching transmission lines, on-chip metal-insulator-metal shunt capacitors, series thin-film resistors, and matching stubs were used in the design. Series resistors in the shunt branch arm provide the basic circuit stabilization. The S-MMIC amplifier was measured for S-parameters and found to be centered at 320 GHz with 13-15-dB gain from 300-345 GHz. This chip was developed as part of the DARPA Submillimeter Wave Imaging Focal Plane Technology (SWIFT) program (see figure). Submillimeter-wave amplifiers could enable more sensitive receivers for earth science, planetary remote sensing, and astrophysics telescopes, particularly in radio astronomy, both from the ground and in space. A small atmospheric window at 340 GHz exists and could enable ground-based observations. However, the submillimeter-wave regime (above 300 GHz) is best used for space telescopes as Earth s atmosphere attenuates most of the signal through water and oxygen absorption. Future radio telescopes could make use of S-MMIC amplifiers for wideband, low noise, instantaneous frequency coverage, particularly in the case of heterodyne array receivers.

  9. Stimulated Raman scattering of sub-millimeter waves in bismuth

    Science.gov (United States)

    Kumar, Pawan; Tripathi, V. K.

    2007-12-01

    A high-power sub-millimeter wave propagating through bismuth, a semimetal with non-spherical energy surfaces, parametrically excites a space-charge mode and a back-scattered electromagnetic wave. The free carrier density perturbation associated with the space-charge wave couples with the oscillatory velocity due to the pump to derive the scattered wave. The scattered and pump waves exert a pondermotive force on electrons and holes, driving the space-charge wave. The collisional damping of the decay waves determines the threshold for the parametric instability. The threshold intensity for 20 μm wavelength pump turns out to be ˜2×1012 W/cm2. Above the threshold, the growth rate scales increase with ωo, attain a maximum around ωo=6.5ωp, and, after this, falls off.

  10. The DC-8 Submillimeter-Wave Cloud Ice Radiometer

    Science.gov (United States)

    Walter, Steven J.; Batelaan, Paul; Siegel, Peter; Evans, K. Franklin; Evans, Aaron; Balachandra, Balu; Gannon, Jade; Guldalian, John; Raz, Guy; Shea, James

    2000-01-01

    An airborne radiometer is being developed to demonstrate the capability of radiometry at submillimeter-wavelengths to characterize cirrus clouds. At these wavelengths, cirrus clouds scatter upwelling radiation from water vapor in the lower troposphere. Radiometric measurements made at multiple widely spaced frequencies permit flux variations caused by changes in scattering due to crystal size to be distinguished from changes in cloud ice content. Measurements at dual polarizations can also be used to constrain the mean crystal shape. An airborne radiometer measuring the upwelling submillimeter-wave flux should then able to retrieve both bulk and microphysical cloud properties. The radiometer is being designed to make measurements at four frequencies (183 GHz, 325 GHz, 448 GHz, and 643 GHz) with dual-polarization capability at 643 GHz. The instrument is being developed for flight on NASA's DC-8 and will scan cross-track through an aircraft window. Measurements with this radiometer in combination with independent ground-based and airborne measurements will validate the submillimeter-wave radiometer retrieval techniques. The goal of this effort is to develop a technique to enable spaceborne characterization of cirrus, which will meet a key climate measurement need. The development of an airborne radiometer to validate cirrus retrieval techniques is a critical step toward development of spaced-based radiometers to investigate and monitor cirrus on a global scale. The radiometer development is a cooperative effort of the University of Colorado, Colorado State University, Swales Aerospace, and Jet Propulsion Laboratory and is funded by the NASA Instrument Incubator Program.

  11. SUBMILLIMETER-WAVE ROTATIONAL SPECTROSCOPY OF H2F+

    International Nuclear Information System (INIS)

    Fujimori, R.; Kawaguchi, K.; Amano, T.

    2011-01-01

    Five pure rotational transitions of H 2 F + generated by a discharge in an HF/H 2 /Ar mixture were observed in the range 473-774 GHz with a backward-wave oscillator based submillimeter-wave spectrometer. A simultaneous analysis of the rotational lines with 120 combination differences for the ground state derived from the infrared spectra was carried out to determine the precise molecular constants for the ground state. The rotational transition frequencies that lie below 2 THz were calculated, together with their estimated uncertainties, to facilitate future astronomical identifications. The chemistry for H 2 F + formation in interstellar space is discussed in comparison with a case for recently detected H 2 Cl + .

  12. InP HEMT Integrated Circuits for Submillimeter Wave Radiometers in Earth Remote Sensing

    Science.gov (United States)

    Deal, William R.; Chattopadhyay, Goutam

    2012-01-01

    The operating frequency of InP integrated circuits has pushed well into the Submillimeter Wave frequency band, with amplification reported as high as 670 GHz. This paper provides an overview of current performance and potential application of InP HEMT to Submillimeter Wave radiometers for earth remote sensing.

  13. Integrated flux-flow oscillators for submillimeter wave receivers

    International Nuclear Information System (INIS)

    Koshelets, V.P.; Shchukin, A.V.; Shitov, S.V.; Filippenko, L.V.; Fischer, G.M.; Mygind, J.

    1994-01-01

    A superconducting Flux-Flow Oscillator (FFO) integrated on the same chip with a small Josephson junction detector has been experimentally investigated in the frequency range 100 - 450 GHz. Both the emitted power and the frequency of the FFO can be varied by adjusting the dc bias current and/or the applied dc magnetic field. Microwave powers as high as 0.3 μW have been measured at 375 GHz. The spectral width of the FFO is about 1 MHz as estimated from harmonic mixing experiments. Also a fully integrated superconducting submillimeter wave receiver using the FFO as local oscillator has been successfully tested. The circuit included coupling transformers, a superconducting variable attenuator and a detector junction with tuned-out capacitance. (orig.)

  14. Compact Receiver Front Ends for Submillimeter-Wave Applications

    Science.gov (United States)

    Mehdi, Imran; Chattopadhyay, Goutam; Schlecht, Erich T.; Lin, Robert H.; Sin, Seth; Peralta, Alejandro; Lee, Choonsup; Gill, John J.; Gulkis, Samuel; Thomas, Bertrand C.

    2012-01-01

    The current generation of submillimeter-wave instruments is relatively mass and power-hungry. The receiver front ends (RFEs) of a submillimeter instrument form the heart of the instrument, and any mass reduction achieved in this subsystem is propagated through the instrument. In the current implementation, the RFE consists of different blocks for the mixer and LO circuits. The motivation for this work is to reduce the mass of the RFE by integrating the mixer and LO circuits in one waveguide block. The mixer and its associated LO chips will all be packaged in a single waveguide package. This will reduce the mass of the RFE and also provide a number of other advantages. By bringing the mixer and LO circuits close together, losses in the waveguide will be reduced. Moreover, the compact nature of the block will allow for better thermal control of the block, which is important in order to reduce gain fluctuations. A single waveguide block with a 600- GHz RFE functionality (based on a subharmonically pumped Schottky diode pair) has been demonstrated. The block is about 3x3x3 cubic centimeters. The block combines the mixer and multiplier chip in a single package. 3D electromagnetic simulations were carried out to design the waveguide circuit around the mixer and multiplier chip. The circuit is optimized to provide maximum output power and maximum bandwidth. An integrated submillimeter front end featuring a 520-600-GHz sub-harmonic mixer and a 260-300-GHz frequency tripler in a single cavity was tested. Both devices used GaAs MMIC membrane planar Schottky diode technology. The sub-harmonic mixer/tripler circuit has been tested using conventional metal-machined blocks. Measurement results on the metal block give best DSB (double sideband) mixer noise temperature of 2,360 K and conversion losses of 7.7 dB at 520 GHz. The LO input power required to pump the integrated tripler/sub-harmonic mixer is between 30 and 50 mW.

  15. Planar Submillimeter-Wave Mixer Technology with Integrated Antenna

    Science.gov (United States)

    Chattopadhyay, Gautam; Mehdi, Imran; Gill, John J.; Lee, Choonsup; lombart, Muria L.; Thomas, Betrand

    2010-01-01

    High-performance mixers at terahertz frequencies require good matching between the coupling circuits such as antennas and local oscillators and the diode embedding impedance. With the availability of amplifiers at submillimeter wavelengths and the need to have multi-pixel imagers and cameras, planar mixer architecture is required to have an integrated system. An integrated mixer with planar antenna provides a compact and optimized design at terahertz frequencies. Moreover, it leads to a planar architecture that enables efficient interconnect with submillimeter-wave amplifiers. In this architecture, a planar slot antenna is designed on a thin gallium arsenide (GaAs) membrane in such a way that the beam on either side of the membrane is symmetric and has good beam profile with high coupling efficiency. A coplanar waveguide (CPW) coupled Schottky diode mixer is designed and integrated with the antenna. In this architecture, the local oscillator (LO) is coupled through one side of the antenna and the RF from the other side, without requiring any beam sp litters or diplexers. The intermediate frequency (IF) comes out on a 50-ohm CPW line at the edge of the mixer chip, which can be wire-bonded to external circuits. This unique terahertz mixer has an integrated single planar antenna for coupling both the radio frequency (RF) input and LO injection without any diplexer or beamsplitters. The design utilizes novel planar slot antenna architecture on a 3- mthick GaAs membrane. This work is required to enable future multi-pixel terahertz receivers for astrophysics missions, and lightweight and compact receivers for planetary missions to the outer planets in our solar system. Also, this technology can be used in tera hertz radar imaging applications as well as for testing of quantum cascade lasers (QCLs).

  16. Progress in passive submillimeter-wave video imaging

    Science.gov (United States)

    Heinz, Erik; May, Torsten; Born, Detlef; Zieger, Gabriel; Peiselt, Katja; Zakosarenko, Vyacheslav; Krause, Torsten; Krüger, André; Schulz, Marco; Bauer, Frank; Meyer, Hans-Georg

    2014-06-01

    Since 2007 we are developing passive submillimeter-wave video cameras for personal security screening. In contradiction to established portal-based millimeter-wave scanning techniques, these are suitable for stand-off or stealth operation. The cameras operate in the 350GHz band and use arrays of superconducting transition-edge sensors (TES), reflector optics, and opto-mechanical scanners. Whereas the basic principle of these devices remains unchanged, there has been a continuous development of the technical details, as the detector array, the scanning scheme, and the readout, as well as system integration and performance. The latest prototype of this camera development features a linear array of 128 detectors and a linear scanner capable of 25Hz frame rate. Using different types of reflector optics, a field of view of 1×2m2 and a spatial resolution of 1-2 cm is provided at object distances of about 5-25m. We present the concept of this camera and give details on system design and performance. Demonstration videos show its capability for hidden threat detection and illustrate possible application scenarios.

  17. Millimeter and submillimeter wave spectroscopy: molecules of astrophysical interest

    International Nuclear Information System (INIS)

    Plummer, G.M.

    1985-01-01

    Species of three general types of molecular ions were studied by means of millimeter-submillimeter (mm/sub-mm) wave spectroscopy. Because of their highly reactive nature, it has been possible to study ionic species in the microwave region for only the past ten is presented here. A new method is presented here for production of such molecular ions in concentrations greater by one to two orders of magnitude than possible with previous techniques, and the subsequent first mm/sub/mm/ detections of two isotopic forms of HCO + , three isotopic forms of ArD + , and the molecular ion H 3 O + . Simple neutral species, which are generally less reactive than ions, are also present in relatively large concentrations in the interstellar medium and in the atmospheres of cool stars themselves. Presented here is the first laboratory microwave detection of two isotopic species of LiH 2 , a solid at normal temperatures and pressures. In addition, a combined analysis of these data, additional data collected on the related species LiD, and existing data on LiD is presented. Finally, a large fraction of the mm/sub/mm/ emissions observed toward the interstellar medium were shown to belong to a small number of relatively heavy, stable, but spectroscopically complicated molecules, many of them internal rotors

  18. Small Explorer project: Submillimeter Wave Astronomy Satellite (SWAS). Mission operations and data analysis plan

    Science.gov (United States)

    Melnick, Gary J.

    1990-01-01

    The Mission Operations and Data Analysis Plan is presented for the Submillimeter Wave Astronomy Satellite (SWAS) Project. It defines organizational responsibilities, discusses target selection and navigation, specifies instrument command and data requirements, defines data reduction and analysis hardware and software requirements, and discusses mission operations center staffing requirements.

  19. Thin-film VO2 submillimeter-wave modulators and polarizers

    International Nuclear Information System (INIS)

    Fan, J.C.C.; Fetterman, H.R.; Bachner, F.J.; Zavracky, P.M.; Parker, C.D.

    1977-01-01

    Submillimeter-wave modulators and switchable polarizers have been fabricated from VO 2 thin films deposited on sapphire substrates. By passing electric current pulses through elements made from these films, the films can be thermally cycled through the insulator-to-metal transition that occurs in VO 2 at about 65 degreeC. In the insulating state, the films are found to have negligible effect on the transmission at submillimeter wavelengths, while above the phase transition the transmission is strongly reduced by the free-electron effects characteristic of a metal. Other possible applications of such switchable VO 2 elements include variable bandpass filters and diffraction grating beam-steering devices

  20. Superconducting Hot-Electron Submillimeter-Wave Detector

    Science.gov (United States)

    Karasik, Boris; McGrath, William; Leduc, Henry

    2009-01-01

    A superconducting hot-electron bolometer has been built and tested as a prototype of high-sensitivity, rapid-response detectors of submillimeter-wavelength radiation. There are diverse potential applications for such detectors, a few examples being submillimeter spectroscopy for scientific research; detection of leaking gases; detection of explosive, chemical, and biological weapons; and medical imaging. This detector is a superconducting-transition- edge device. Like other such devices, it includes a superconducting bridge that has a low heat capacity and is maintained at a critical temperature (T(sub c)) at the lower end of its superconducting-transition temperature range. Incident photons cause transient increases in electron temperature through the superconducting-transition range, thereby yielding measurable increases in electrical resistance. In this case, T(sub c) = 6 K, which is approximately the upper limit of the operating-temperature range of silicon-based bolometers heretofore used routinely in many laboratories. However, whereas the response speed of a typical silicon- based laboratory bolometer is characterized by a frequency of the order of a kilohertz, the response speed of the present device is much higher characterized by a frequency of the order of 100 MHz. For this or any bolometer, a useful figure of merit that one seeks to minimize is (NEP)(tau exp 1/2), where NEP denotes the noise-equivalent power (NEP) and the response time. This figure of merit depends primarily on the heat capacity and, for a given heat capacity, is approximately invariant. As a consequence of this approximate invariance, in designing a device having a given heat capacity to be more sensitive (to have lower NEP), one must accept longer response time (slower response) or, conversely, in designing it to respond faster, one must accept lower sensitivity. Hence, further, in order to increase both the speed of response and the sensitivity, one must make the device very small in

  1. An adjustable RF tuning element for microwave, millimeter wave, and submillimeter wave integrated circuits

    Science.gov (United States)

    Lubecke, Victor M.; Mcgrath, William R.; Rutledge, David B.

    1991-01-01

    Planar RF circuits are used in a wide range of applications from 1 GHz to 300 GHz, including radar, communications, commercial RF test instruments, and remote sensing radiometers. These circuits, however, provide only fixed tuning elements. This lack of adjustability puts severe demands on circuit design procedures and materials parameters. We have developed a novel tuning element which can be incorporated into the design of a planar circuit in order to allow active, post-fabrication tuning by varying the electrical length of a coplanar strip transmission line. It consists of a series of thin plates which can slide in unison along the transmission line, and the size and spacing of the plates are designed to provide a large reflection of RF power over a useful frequency bandwidth. Tests of this structure at 1 GHz to 3 Ghz showed that it produced a reflection coefficient greater than 0.90 over a 20 percent bandwidth. A 2 GHz circuit incorporating this tuning element was also tested to demonstrate practical tuning ranges. This structure can be fabricated for frequencies as high as 1000 GHz using existing micromachining techniques. Many commercial applications can benefit from this micromechanical RF tuning element, as it will aid in extending microwave integrated circuit technology into the high millimeter wave and submillimeter wave bands by easing constraints on circuit technology.

  2. Pressure broadening measurement of submillimeter-wave lines of O3

    International Nuclear Information System (INIS)

    Yamada, M.M.; Amano, T.

    2005-01-01

    The pressure broadening coefficients and their temperature dependences for two submillimeter-wave transitions of ozone, one being monitored with Odin and the other to be monitored with JEM/SMILES and EOS-MLS, have been determined by using a BWO based submillimeter-wave spectrometer. The measurements have also been extended to one of the symmetric isotopic species, 16 O 18 O 16 O. The isotopic species is observed in natural abundance and as a consequence the temperature dependence is not determined due to weak signal intensity. The pressure broadening parameters are determined with better than 1% accuracy, while the temperature dependence exponents are obtained within 1.5-3% accuracy for the normal species transitions

  3. Compact Submillimeter-Wave Receivers Made with Semiconductor Nano-Fabrication Technologies

    Science.gov (United States)

    Jung, C.; Thomas, B.; Lee, C.; Peralta, A.; Chattopadhyay, G.; Gill, J.; Cooper, K.; Mehdi, I.

    2011-01-01

    Advanced semiconductor nanofabrication techniques are utilized to design, fabricate and demonstrate a super-compact, low-mass (<10 grams) submillimeter-wave heterodyne front-end. RF elements such as waveguides and channels are fabricated in a silicon wafer substrate using deep-reactive ion etching (DRIE). Etched patterns with sidewalls angles controlled with 1 deg precision are reported, while maintaining a surface roughness of better than 20 nm rms for the etched structures. This approach is being developed to build compact 2-D imaging arrays in the THz frequency range.

  4. Design considerations for large detector arrays on submillimeter-wave telescopes

    Science.gov (United States)

    Stark, Antony A.

    2000-07-01

    The emerging technology of large (approximately 10,000 pixel) submillimeter-wave bolometer arrays presents a novel optical design problem -- how can such arrays be fed by diffraction- limited telescope optics where the primary mirror is less than 100,000 wavelengths in diameter? Standard Cassegrain designs for radiotelescope optics exhibit focal surface curvature so large that detectors cannot be placed more than 25 beam diameters from the central ray. The problem is worse for Ritchey-Chretien designs, because these minimize coma while increasing field curvature. Classical aberrations, including coma, are usually dominated by diffraction in submillimeter- wave single dish telescopes. The telescope designer must consider (1) diffraction, (2) aberration, (3) curvature of field, (4) cross-polarization, (5) internal reflections, (6) the effect of blockages, (7) means of beam chopping on- and off-source, (8) gravitational and thermal deformations of the primary mirror, (9) the physical mounting of large detector packages, and (10) the effect of gravity and (11) vibration on those detectors. Simultaneous optimization of these considerations in the case of large detector arrays leads to telescopes that differ considerably from standard radiotelescope designs. Offset optics provide flexibility for mounting detectors, while eliminating blockage and internal reflections. Aberrations and cross-polarization can be the same as on-axis designs having the same diameter and focal length. Trade-offs include the complication of primary mirror homology and an increase in overall cost. A dramatic increase in usable field of view can be achieved using shaped optics. Solutions having one to six mirrors will be discussed, including possible six-mirror design for the proposed South Pole 10 m telescope.

  5. Plasma scattering measurement using a submillimeter wave gyrotron as a radiation source

    International Nuclear Information System (INIS)

    Ogawa, I.; Idehara, T.; Itakura, Y.; Myodo, M.; Hori, T.; Hatae, T.

    2004-01-01

    Plasma scattering measurement is an effective technique to observe low frequency density fluctuations excited in plasma. The spatial and wave number resolutions and the S/N ratio of measurement depend on the wavelength range, the size and the intensity of a probe beam. A well-collimated, submillimeter wave beam is suitable for improving the spatial and wave number resolutions. Application of high frequency gyrotron is effective in improving the S/N ratio of the measurement because of its capacity to deliver high power. Unlike the molecular vapor lasers, the gyrotrons generate diverging beam of radiation with TE mn mode structure. It is therefore necessary to convert the output radiation into a Gaussian beam. A quasi-optical antenna is a suitable element for the conversion system under consideration since it is applicable to several TE 0n and TE 1n modes. In order to apply the gyrotron to plasma scattering measurement, we have stabilized the output (P = 110 W, f = 354 GHz) of gyrotron up to the level (ΔP/P < 1 %, Δf< 10 kHz). The gyrotron output can be stabilized by decreasing the fluctuation of the cathode potential. (authors)

  6. Icecube: Spaceflight Validation of an 874-GHz Submillimeter Wave Radiometer for Ice Cloud Remote Sensing

    Science.gov (United States)

    Wu, D. L.; Esper, J.; Ehsan, N.; Piepmeier, J. R.; Racette, P.

    2014-12-01

    Ice clouds play a key role in the Earth's radiation budget, mostly through their strong regulation of infrared radiation exchange. Submillimeter wave remote sensing offers a unique capability to improve cloud ice measurements from space. At 874 GHz cloud scattering produces a larger brightness temperature depression from cirrus than lower frequencies, which can be used to retrieve vertically-integrated cloud ice water path (IWP) and ice particle size. The objective of the IceCube project is to retire risks of 874-GHz receiver technology by raising its TRL from 5 to 7. The project will demonstrate, on a 3-U CubeSat in a low Earth orbit (LEO) environment, the 874-GHz receiver system with noise equivalent differential temperature (NEDT) of ~0.2 K for 1-second integration and calibration error of 2.0 K or less as measured from deep-space observations. The Goddard Space Flight Center (GSFC) is partnering with Virginia Diodes, Inc (VDI) to qualify commercially available 874-GHz receiver technology for spaceflight, and demonstrate the radiometer performance. The instrument (submm-wave cloud radiometer, or SCR), along with the CubeSat system developed and integrated by GSFC, will be ready for launch in two years. The instrument subsystem includes a reflector antenna, sub-millimeter wave mixer, frequency multipliers and stable local oscillator, an intermediate frequency (IF) circuit with noise injection, and data-power boards. The mixer and frequency multipliers are procured from VDI with GSFC insight into fabrication and testing processes to ensure scalability to spaceflight beyond TRL 7. The remaining components are a combination of GSFC-designed and commercial off-the-shelf (COTS) at TRLs of 5 or higher. The spacecraft system is specified by GSFC and comprises COTS components including three-axis stabilizer and sun sensor, GPS receiver, deployable solar arrays, UHF radio, and 2 GB of on-board storage. The spacecraft and instrument are integrated and flight qualified

  7. Millimeter and Submillimeter Wave Spectroscopy of Higher Energy Conformers of 1,2-PROPANEDIOL

    Science.gov (United States)

    Zakharenko, Olena; Bossa, Jean-Baptiste; Lewen, Frank; Schlemmer, Stephan; Müller, Holger S. P.

    2017-06-01

    We have performed a study of the millimeter/submillimeter wave spectrum of four higher energy conformers of 1,2-propanediol (continuation of the previous study on the three lowest energy conformers. The present analysis of rotational transitions carried out in the frequency range 38 - 400 GHz represents a significant extension of previous microwave work. The new data were combined with previously-measured microwave transitions and fitted using a Watson's S-reduced Hamiltonian. The final fits were within experimental accuracy, and included spectroscopic parameters up to sixth order of angular momentum, for the ground states of the four higher energy conformers following previously studied ones: g'Ga, gG'g', aGg' and g'Gg. The present analysis provides reliable frequency predictions for astrophysical detection of 1,2-propanediol by radio telescope arrays at millimeter wavelengths. J.-B. Bossa, M.H. Ordu, H.S.P. Müller, F. Lewen, S. Schlemmer, A&A 570 (2014) A12)

  8. A retrieval algorithm of hydrometer profile for submillimeter-wave radiometer

    Science.gov (United States)

    Liu, Yuli; Buehler, Stefan; Liu, Heguang

    2017-04-01

    Vertical profiles of particle microphysics perform vital functions for the estimation of climatic feedback. This paper proposes a new algorithm to retrieve the profile of the parameters of the hydrometeor(i.e., ice, snow, rain, liquid cloud, graupel) based on passive submillimeter-wave measurements. These parameters include water content and particle size. The first part of the algorithm builds the database and retrieves the integrated quantities. Database is built up by Atmospheric Radiative Transfer Simulator(ARTS), which uses atmosphere data to simulate the corresponding brightness temperature. Neural network, trained by the precalculated database, is developed to retrieve the water path for each type of particles. The second part of the algorithm analyses the statistical relationship between water path and vertical parameters profiles. Based on the strong dependence existing between vertical layers in the profiles, Principal Component Analysis(PCA) technique is applied. The third part of the algorithm uses the forward model explicitly to retrieve the hydrometeor profiles. Cost function is calculated in each iteration, and Differential Evolution(DE) algorithm is used to adjust the parameter values during the evolutionary process. The performance of this algorithm is planning to be verified for both simulation database and measurement data, by retrieving profiles in comparison with the initial one. Results show that this algorithm has the ability to retrieve the hydrometeor profiles efficiently. The combination of ARTS and optimization algorithm can get much better results than the commonly used database approach. Meanwhile, the concept that ARTS can be used explicitly in the retrieval process shows great potential in providing solution to other retrieval problems.

  9. Submillimeter-wave measurements of the pressure broadening of BrO

    International Nuclear Information System (INIS)

    Yamada, M.M.; Kobayashi, M.; Habara, H.; Amano, T.; Drouin, B.J.

    2003-01-01

    The N 2 and O 2 pressure broadening coefficients of the J=23.5 ↔ 22.5 and J=25.5 ↔ 24.5 rotational transitions in the ground vibronic state X 2 Π 3/2 of 81 BrO at 624.768 and 650.178 GHz have been independently measured at Ibaraki University and Jet Propulsion Laboratory. These lines are expected to be monitored by the superconducting submillimeter-wave limb emission sounder in the Japanese Experiment Module on the International Space Station (JEM/SMILES) as well as the earth observing system microwave limb sounder (EOS-MLS). This work provides temperature-dependent pressure broadening parameters of BrO needed by the space station and satellite based observations. The BrO pressure broadening coefficients and their 1σ uncertainties are: γ 0 (N 2 )=3.24±0.05 MHz/Torr and γ 0 (O 2 )=2.33±0.06 MHz/Torr for the 624.768 GHz transition at room temperature (296 K). For the 650.178 GHz line, the results are: γ 0 (N 2 )=3.20±0.07 MHz/Torr and γ 0 (O 2 )=2.41±0.06 MHz/Torr. The temperature dependence exponents and their 1σ error are determined to be: n(N 2 )=-0.76±0.05 and n(O 2 )=-0.93±0.07 for the 624.768 GHz transition, and n(N 2 )=-0.84±0.07 and n(O 2 )=-0.70±0.07 for the 650.178 GHz transition

  10. Submillimeter molecular spectroscopy with the Texas millimeter wave observatory radio telescope

    International Nuclear Information System (INIS)

    Loren, R.B.; Wootten, A.; National Radio Astronomy Observatory, Charlottesville, VA)

    1986-01-01

    A large number of previously unreported molecular transitions have been detected in the submillimeter wavelength band toward OMC-1 and M17 SW using the Texas 4.9 m radio antenna. The emission components in OMC-1 that come from the unresolved plateau and hot core regions are stronger in these higher energy transitions than in the lower-energy, lower-frequency lines. Intense, probably thermalized high J SiO lines require a very hot core if they arise in a region the same size as that mapped in J = 2-1 SiO by interferometer measurements. Despite the high energy levels of the submillimeter lines of CN and CCH, there is no broad emission component evident, consistent with their greatly reduced abundance due to removal by chemical reactions. 33 references

  11. Solar Flash Sub-Millimeter Wave Range Spectrum Part Radiation Modeling

    Directory of Open Access Journals (Sweden)

    V. Yu. Shustikov

    2015-01-01

    Full Text Available Currently, solar flares are under observation on the RT-7.5 radio telescope of BMSTU. This telescope operates in a little-studied range of the spectrum, at wavelengths of 3.2 and 2.2 mm (93 and 140 GHz, thereby providing unique information about parameters of the chromosphere plasma and zone of the temperature minimum. Observations on various instruments provided relatively small amount of data on the radio emission flare at frequencies close to 93 GHz, and at frequency of 140 GHz such observations were not carried out. For these reasons, data collected from the RT-7.5 radio telescope are of high value (Shustikov et al., 2012.This work describes modeling and gives interpretation of the reason for raising flux density spectrum of sub-millimeter radio frequency emission using as an example the GOES flare of class M 5.3 occurred on 04.07.2012 in the active region 11515. This flare was observed on the RT-7.5 radio telescope of BMSTU and was described by Shustikov et al. (2012 and by Smirnova et al. (2013, where it has been suggested that the reason for raising radio frequency emission is a bremsstrahlung of the thermal electrons in the hot plasma of the solar chromosphere. Rough estimates of the plasma temperature at the flare source were obtained.This paper proposes model calculations of the flux density spectrum of the sub-millimeter radio emission based on the gyrosynchrotron Fleischman-Kuznetsov code (Fleishman & Kuznetsov, 2010. Section 1 briefly describes observational data, tools and processing methods used in the work. Section 2 shows results of modeling the flare radio emission. Section 3 discusses results and conclusions.Numerical modeling the sub-millimeter part of the spectrum of the radio flux density for the GOES flare of class M5.3 has been carried out. This flare occurred in the active region 11515 on 04.07.2012. Modeling was based on the observations on the BMSTU’s RT-7.5 radio telescope.The paper draws conclusion based on the

  12. New development of solid state sub-millimeter sources

    International Nuclear Information System (INIS)

    Nishizawa, Jun-ichi

    1982-01-01

    The TUNNETT (tunnel injection transit time negative resistance) diode was proposed by the author in the analysis of avalanching negative resistance diodes and seemed to be the most promising semiconductor source in the frequency range from 100 to 1000 GHz. The first TUNNETT oscillation was realized experimentally in 1968 from a GaAs p + n diode. Recently, several types of GaAs TUNNETT diodes have been fabricated by the use of the author's new liquid phase epitaxial method, which is named the temperature difference method under controlled vapour pressure. The oscillation characteristics of p + - n - n + diodes are shown. On the other hand, the static induction transistor (SIT) shows the excellent performance for high power use in microwave region. The static induced tunnel transit time transistor (SIT 4 ) is a kind of SIT in which the injection source region is replaced by the tunnel injection for use in submillimeter region. In SIT 4 , the gate voltage controls the field of the tunnelling region, and the tunnelling electrons transit to the drain without reaching the gate. The SIT's using tunnelling and ideal (ballistic) SIT are promising devices in submillimeter region. The author suggested the generation of electromagnetic waves by using phonons in semiconductors from submillimeter to infared. Above 1000 GHz up to 100 THz of the field of conventional semiconductors, semiconductor Raman and Brillouin lasers are expected to be the most useful devices in the future. (Wakatsuki, Y.)

  13. Achromatic half-wave plate for submillimeter instruments in cosmic microwave background astronomy: experimental characterization.

    Science.gov (United States)

    Pisano, Giampaolo; Savini, Giorgio; Ade, Peter A R; Haynes, Vic; Gear, Walter K

    2006-09-20

    An achromatic half-wave plate (HWP) to be used in millimeter cosmic microwave background (CMB) polarization experiments has been designed, manufactured, and tested. The design is based on the 5-plates Pancharatnam recipe and it works in the frequency range 85-185 GHz. A model has been used to predict the transmission, reflection, absorption, and phase shift as a function of frequency. The HWP has been tested by using coherent radiation from a back-wave oscillator to investigate its modulation efficiency and with incoherent radiation from a polarizing Fourier transform spectrometer (FTS) to explore its frequency behavior. The FTS measurements have been fitted with an optical performance model which is in excellent agreement with the data. A detailed analysis of the data also allows a precise determination of the HWP fast and slow axes in the frequency band of operation. A list of the HWP performance characteristics is reported including estimates of its cross polarization.

  14. Achromatic half-wave plate for submillimeter instruments in cosmic microwave background astronomy: modeling and simulation.

    Science.gov (United States)

    Savini, Giorgio; Pisano, Giampaolo; Ade, Peter A R

    2006-12-10

    We adopted an existing formalism and modified it to simulate, with high precision, the transmission, reflection, and absorption of multiple-plate birefringent devices as a function of frequency. To validate the model, we use it to compare the measured properties of an achromatic five-plate device with a broadband antireflection coating to expectations derived from the material optical constants and its geometric configuration. The half-wave plate presented here is observed to perform well with a phase shift variation of < 2 degrees from the ideal 180 degrees over a bandwidth of Deltav/v approximately 1 at millimeter wavelengths. This formalism represents a powerful design tool for birefringent polarization modulators and enables its optical properties to be specified with high accuracy.

  15. Coherent molecular transistor: control through variation of the gate wave function.

    Science.gov (United States)

    Ernzerhof, Matthias

    2014-03-21

    In quantum interference transistors (QUITs), the current through the device is controlled by variation of the gate component of the wave function that interferes with the wave function component joining the source and the sink. Initially, mesoscopic QUITs have been studied and more recently, QUITs at the molecular scale have been proposed and implemented. Typically, in these devices the gate lead is subjected to externally adjustable physical parameters that permit interference control through modifications of the gate wave function. Here, we present an alternative model of a molecular QUIT in which the gate wave function is directly considered as a variable and the transistor operation is discussed in terms of this variable. This implies that we specify the gate current as well as the phase of the gate wave function component and calculate the resulting current through the source-sink channel. Thus, we extend on prior works that focus on the phase of the gate wave function component as a control parameter while having zero or certain discrete values of the current. We address a large class of systems, including finite graphene flakes, and obtain analytic solutions for how the gate wave function controls the transistor.

  16. Coherent molecular transistor: Control through variation of the gate wave function

    International Nuclear Information System (INIS)

    Ernzerhof, Matthias

    2014-01-01

    In quantum interference transistors (QUITs), the current through the device is controlled by variation of the gate component of the wave function that interferes with the wave function component joining the source and the sink. Initially, mesoscopic QUITs have been studied and more recently, QUITs at the molecular scale have been proposed and implemented. Typically, in these devices the gate lead is subjected to externally adjustable physical parameters that permit interference control through modifications of the gate wave function. Here, we present an alternative model of a molecular QUIT in which the gate wave function is directly considered as a variable and the transistor operation is discussed in terms of this variable. This implies that we specify the gate current as well as the phase of the gate wave function component and calculate the resulting current through the source-sink channel. Thus, we extend on prior works that focus on the phase of the gate wave function component as a control parameter while having zero or certain discrete values of the current. We address a large class of systems, including finite graphene flakes, and obtain analytic solutions for how the gate wave function controls the transistor

  17. Submillimeter wave spectroscopy of ethyl isocyanide and its searches in Orion

    Science.gov (United States)

    Margulès, L.; Tercero, B.; Guillemin, J. C.; Motiyenko, R. A.; Cernicharo, J.

    2018-02-01

    Context. About 40 cyanide compounds have been detected in the interstellar medium, but only 3 examples of organic isocyanide compounds were observed in this medium. Ethyl isocyanide is one of the best candidates for possible detection. Aim. To date, measurements of rotational spectra are limited to 40 GHz. The extrapolation of the prediction in the millimeter wave domain is inaccurate and does not permit an unambiguous detection. Methods: The rotational spectra were reinvestigated from 0.15 to 1 THz. Using the new prediction, we searched for the compound ethyl isocyanide in Orion KL and Sgr B2. Results: We newly assigned 2906 transitions and fitted these new data with those from previous studies, reaching quantum numbers up to J = 103 and Ka = 30. The asymmetric top Hamiltonian proposed by Watson in the Ir representation was used for the analysis, and both reductions A and S were tested. The search for CH3CH2NC in Sgr B2 (IRAM 30m) and Orion KL (IRAM 30m, ALMA Science Verification) result in a non-detection; upper limits to the column density were derived. Tables S1-S4 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/610/A44

  18. Steering of quantum waves: Demonstration of Y-junction transistors using InAs quantum wires

    Science.gov (United States)

    Jones, Gregory M.; Qin, Jie; Yang, Chia-Hung; Yang, Ming-Jey

    2005-06-01

    In this paper we demonstrate using an InAs quantum wire Y-branch switch that the electron wave can be switched to exit from the two drains by a lateral gate bias. The gating modifies the electron wave functions as well as their interference pattern, causing the anti-correlated, oscillatory transconductances. Our result suggests a new transistor function in a multiple-lead ballistic quantum wire system.

  19. Continuous-Wave Single-Photon Transistor Based on a Superconducting Circuit

    DEFF Research Database (Denmark)

    Kyriienko, Oleksandr; Sørensen, Anders Søndberg

    2016-01-01

    We propose a microwave frequency single-photon transistor which can operate under continuous wave probing and represents an efficient single microwave photon detector. It can be realized using an impedance matched system of a three level artificial ladder-type atom coupled to two microwave cavities...... and the appearance of a photon flux leaving the second cavity through a separate input-output port. The proposal does not require time variation of the probe signals, thus corresponding to a passive version of a single-photon transistor. The resulting device is robust to qubit dephasing processes, possesses low dark...

  20. Full-Wave Analysis of Traveling-Wave Field-Effect Transistors Using Finite-Difference Time-Domain Method

    Directory of Open Access Journals (Sweden)

    Koichi Narahara

    2012-01-01

    Full Text Available Nonlinear transmission lines, which define transmission lines periodically loaded with nonlinear devices such as varactors, diodes, and transistors, are modeled in the framework of finite-difference time-domain (FDTD method. Originally, some root-finding routine is needed to evaluate the contributions of nonlinear device currents appropriately to the temporally advanced electrical fields. Arbitrary nonlinear transmission lines contain large amount of nonlinear devices; therefore, it costs too much time to complete calculations. To reduce the calculation time, we recently developed a simple model of diodes to eliminate root-finding routines in an FDTD solver. Approximating the diode current-voltage relation by a piecewise-linear function, an extended Ampere's law is solved in a closed form for the time-advanced electrical fields. In this paper, we newly develop an FDTD model of field-effect transistors (FETs, together with several numerical examples that demonstrate pulse-shortening phenomena in a traveling-wave FET.

  1. Residual losses in epitaxial thin films of YBa2Cu3O7 from microwave to submillimeter wave frequencies

    International Nuclear Information System (INIS)

    Miller, D.; Richards, P.L.; Etemad, S.; Inam, A.; Venkatesan, T.; Dutta, B.; Wu, X.D.; Eom, C.B.; Geballe, T.H.; Newman, N.; Cole, B.F.

    1991-01-01

    We have measured the residual loss in five epitaxial a-b plane films of the high-T c superconductor YBa 2 Cu 3 O 7 . Microwave measurements near 10 GHz were made by resonance techniques at 4 K. Submillimeter measurements from ∼1.5 to 21 THz were made at 2 K by a direct absorption technique. We use a model of weakly coupled superconducting grains and a homogeneous two-fluid model to fit the data for each film below the well-known absorption edge at 13.5 THz. When the penetration depth determined from muon spin rotation measurements is used to constrain each model, the weakly coupled grain model is able to fit the measured absorptivities for all films, but the two-fluid model is less successful

  2. Detection of Submillimeter-wave [C i] Emission in Gaseous Debris Disks of 49 Ceti and β Pictoris

    Energy Technology Data Exchange (ETDEWEB)

    Higuchi, Aya E.; Sakai, Nami [The Institute of Physical and Chemical Research (RIKEN), 2-1, Hirosawa, Wako-shi, Saitama 351-0198 (Japan); Sato, Aki; Tsukagoshi, Takashi; Momose, Munetake [College of Science, Ibaraki University, Bunkyo 2-1-1, Mito 310-8512 (Japan); Iwasaki, Kazunari [Department of Environmental Systems Science, Doshisha University, Tatara Miyakodani 1-3, Kyotanabe City, Kyoto 610-0394 (Japan); Kobayashi, Hiroshi; Ishihara, Daisuke; Watanabe, Sakae; Kaneda, Hidehiro [Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602 (Japan); Yamamoto, Satoshi, E-mail: aya.higuchi@riken.jp [Department of Physics, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2017-04-10

    We have detected [C i] {sup 3} P {sub 1}–{sup 3} P {sub 0} emissions in the gaseous debris disks of 49 Ceti and β Pictoris with the 10 m telescope of the Atacama Submillimeter Telescope Experiment, which is the first detection of such emissions. The line profiles of [C i] are found to resemble those of CO( J = 3–2) observed with the same telescope and the Atacama Large Millimeter/submillimeter Array. This result suggests that atomic carbon (C) coexists with CO in the debris disks and is likely formed by the photodissociation of CO. Assuming an optically thin [C i] emission with the excitation temperature ranging from 30 to 100 K, the column density of C is evaluated to be (2.2 ± 0.2) × 10{sup 17} and (2.5 ± 0.7) × 10{sup 16} cm{sup −2} for 49 Ceti and β Pictoris, respectively. The C/CO column density ratio is thus derived to be 54 ± 19 and 69 ± 42 for 49 Ceti and β Pictoris, respectively. These ratios are higher than those of molecular clouds and diffuse clouds by an order of magnitude. The unusually high ratios of C to CO are likely attributed to a lack of H{sub 2} molecules needed to reproduce CO molecules efficiently from C. This result implies a small number of H{sub 2} molecules in the gas disk, i.e., there is an appreciable contribution of secondary gas from dust grains.

  3. Enhanced plasma wave detection of terahertz radiation using multiple high electron-mobility transistors connected in series

    KAUST Repository

    Elkhatib, Tamer A.; Kachorovskiǐ, Valentin Yu; Stillman, William J.; Veksler, Dmitry B.; Salama, Khaled N.; Zhang, Xicheng; Shur, Michael S.

    2010-01-01

    We report on enhanced room-temperature detection of terahertz radiation by several connected field-effect transistors. For this enhanced nonresonant detection, we have designed, fabricated, and tested plasmonic structures consisting of multiple InGaAs/GaAs pseudomorphic high electron-mobility transistors connected in series. Results show a 1.63-THz response that is directly proportional to the number of detecting transistors biased by a direct drain current at the same gate-to-source bias voltages. The responsivity in the saturation regime was found to be 170 V/W with the noise equivalent power in the range of 10-7 W/Hz0.5. The experimental data are in agreement with the detection mechanism based on the rectification of overdamped plasma waves excited by terahertz radiation in the transistor channel. © 2010 IEEE.

  4. Enhanced plasma wave detection of terahertz radiation using multiple high electron-mobility transistors connected in series

    KAUST Repository

    Elkhatib, Tamer A.

    2010-02-01

    We report on enhanced room-temperature detection of terahertz radiation by several connected field-effect transistors. For this enhanced nonresonant detection, we have designed, fabricated, and tested plasmonic structures consisting of multiple InGaAs/GaAs pseudomorphic high electron-mobility transistors connected in series. Results show a 1.63-THz response that is directly proportional to the number of detecting transistors biased by a direct drain current at the same gate-to-source bias voltages. The responsivity in the saturation regime was found to be 170 V/W with the noise equivalent power in the range of 10-7 W/Hz0.5. The experimental data are in agreement with the detection mechanism based on the rectification of overdamped plasma waves excited by terahertz radiation in the transistor channel. © 2010 IEEE.

  5. Wide-band Millimeter and Sub-Millimeter Wave Radiometer Instrument to Measure Tropospheric Water and Cloud ICE

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop, fabricate and test a new, multi-frequency millimeter and sub-millimeter-wave radiometer instrument to provide critically-needed measurements...

  6. Solar Observations at Submillimeter Wavelengths

    Science.gov (United States)

    Kaufmann, P.

    We review earlier to recent observational evidences and theoretical motivations leading to a renewed interest to observe flares in the submillimeter (submm) - infrared (IR) range of wavelengths. We describe the new solar dedicated submillimeter wave telescope which began operations at El Leoncito in the Argentina Andes: the SST project. It consists of focal plane arrays of two 405 GHz and four 212 GHz radiometers placed in a 1.5-m radome-enclosed Cassegrain antenna, operating simultaneously with one millisecond time resolution. The first solar events analyzed exhibited the onset of rapid submm-wave spikes (100-300 ms), well associated to other flare manifestations, especially at X-rays. The spikes positions were found scattered over the flaring source by tens of arcseconds. For one event an excellent association was found between the gamma-ray emission time profile and the rate of occurrence of submm-wave rapid spikes. The preliminary results favour the idea that bulk burst emissions are a response to numerous fast energetic injections, discrete in time, produced at different spatial positions over the flaring region. Coronal mass ejections were associated to the events studied. Their trajectories extrapolated to the solar surface appear to correspond to the onset time of the submm-wave spikes, which might represent an early signature of the CME's initial acceleration process.

  7. Planetary submillimeter spectroscopy

    Science.gov (United States)

    Klein, M. J.

    1988-01-01

    The aim is to develop a comprehensive observational and analytical program to study solar system physics and meterology by measuring molecular lines in the millimeter and submillimeter spectra of planets and comets. A primary objective is to conduct observations with new JPL and Caltech submillimeter receivers at the Caltech Submillimeter Observatory (CSO) on Mauna Kea, Hawaii. A secondary objective is to continue to monitor the time variable planetary phenomena (e.g., Jupiter and Uranus) at centimeter wavelength using the NASA antennas of the Deep Space Network (DSN).

  8. Submillimeter-wave measurements of N2 and O2 pressure broadening for HO2 radical generated by Hg-photosensitized reaction

    International Nuclear Information System (INIS)

    Mizoguchi, A.; Yagi, T.; Kondo, K.; Sato, T.O.; Kanamori, H.

    2012-01-01

    The N 2 and O 2 pressure broadening coefficients of the pure rotational transitions at 625.66 GHz (N KaKc =10 1-9 -10 0-10 , J=10.5-10.5) and 649.70 GHz (N KaKc =10 2-9 -9 2-8 , J=9.5-8.5) in the vibronic ground state X 2 A′ of the perhydroxyl (HO 2 ) radical have been determined by precise laboratory measurements. For the production of HO 2 , the mercury-photosensitized reaction of the H 2 and O 2 precursors was used to provide an optimum condition for measurement of the pressure broadening coefficient. The Superconducting Submillimeter-wave Limb Emission Sounder (SMILES) was designed to monitor the volume mixing ratio of trace gases including HO 2 in the Earth's upper atmosphere using these transitions. The precise measurement of pressure broadening coefficient γ in terms of the half width at half maximum is required in order to retrieve the atmospheric volume mixing ratio. In this work, γ coefficients of the 625.66 GHz transition were determined for N 2 and O 2 at room temperature as γ(N 2 )=4.085±0.049 MHz/Torr and γ(O 2 )=2.578±0.047 MHz/Torr with 3σ uncertainty. Similarly, the coefficients of the 649.70 GHz transition were determined as γ(N 2 )=3.489±0.094 MHz/Torr and γ(O 2 )=2.615±0.099 MHz/Torr. The air broadening coefficients for the 625.66 GHz and 649.70 GHz lines were estimated at γ(air)=3.769±0.067 MHz and 3.298±0.099 MHz respectively, where the uncertainty includes possible systematic errors. The newly determined coefficients are compared with previous results and we discuss the advantage of the mercury-photosensitized reaction for HO 2 generation. In comparison with those of other singlet molecules, the pressure broadening coefficients of the HO 2 radical are not much affected by the existence of an unpaired electron.

  9. Millimeter-wave small-signal modeling with optimizing sensitive-parameters for metamorphic high electron mobility transistors

    International Nuclear Information System (INIS)

    Moon, S-W; Baek, Y-H; Han, M; Rhee, J-K; Kim, S-D; Oh, J-H

    2010-01-01

    In this paper, we present a simple and reliable technique for determining the small-signal equivalent circuit model parameters of the 0.1 µm metamorphic high electron mobility transistors (MHEMTs) in a millimeter-wave frequency range. The initial eight extrinsic parameters of the MHEMT are extracted using two S-parameter (scattering parameter) sets measured under the pinched-off and zero-biased cold field-effect transistor conditions by avoiding the forward gate biasing. Furthermore, highly calibration-sensitive values of the R s , L s and C pd are optimized by using a gradient optimization method to improve the modeling accuracy. The accuracy enhancement of this procedure is successfully verified with an excellent correlation between the measured and calculated S-parameters up to 65 GHz

  10. Predictive of the quantum capacitance effect on the excitation of plasma waves in graphene transistors with scaling limit.

    Science.gov (United States)

    Wang, Lin; Chen, Xiaoshuang; Hu, Yibin; Wang, Shao-Wei; Lu, Wei

    2015-04-28

    Plasma waves in graphene field-effect transistors (FETs) and nano-patterned graphene sheets have emerged as very promising candidates for potential terahertz and infrared applications in myriad areas including remote sensing, biomedical science, military, and many other fields with their electrical tunability and strong interaction with light. In this work, we study the excitations and propagation properties of plasma waves in nanometric graphene FETs down to the scaling limit. Due to the quantum-capacitance effect, the plasma wave exhibits strong correlation with the distribution of density of states (DOS). It is indicated that the electrically tunable plasma resonance has a power-dependent V0.8 TG relation on the gate voltage, which originates from the linear dependence of density of states (DOS) on the energy in pristine graphene, in striking difference to those dominated by classical capacitance with only V0.5 TG dependence. The results of different transistor sizes indicate the potential application of nanometric graphene FETs in highly-efficient electro-optic modulation or detection of terahertz or infrared radiation. In addition, we highlight the perspectives of plasma resonance excitation in probing the many-body interaction and quantum matter state in strong correlation electron systems. This study reveals the key feature of plasma waves in decorated/nanometric graphene FETs, and paves the way to tailor plasma band-engineering and expand its application in both terahertz and mid-infrared regions.

  11. New submillimeter detectors and antenna arrays

    International Nuclear Information System (INIS)

    Fetterman, H.R.; Reible, S.A.; Sollner, G.; Parker, C.D.

    1982-01-01

    Preliminary investigation has been made into the use of SIS (superconductor--insulator--superconductor) diodes for possible roles in sub-millimeter imaging systems. That is, extremely low noise, millimeter wave detectors and mixers have recently been reported which depend on single-particle tunnelling between two superconducting films separated by a thin oxide layer. The combination of excellent low-frequency sensitivity and well-developed fabrication technology make the SIS mixers particularly attractive for the systems using antenna structures and arrays in millimeter and submillimeter regions. The SIS diodes of Nb-Nb 2 O 5 -Pb showed a strong video response to the radiation which could be differentiated from the regular Josephson effect since it was not affected by a magnetic field. In exploring the three-terminal devices for possible detector and source applications in submillimeter region, the authors first determined that millimeter and submillimeter radiation could be effectively coupled to and detected in high-frequency FETs. Video response was readily obtained at 800 GHz, and carcinotron radiation at 350 GHz was mixed with the 5th harmonic of a 70 GHz klystron, producing over 45 db signal-to-noise ratio in the intermediate frequency. Since FET can function as a three-terminal oscillator simultaneously detecting submillimeter radiation or optical beats, it has interesting possibility, such as self-oscillating mixers or subharmonic local oscillators. (Wakatsuki, Y.)

  12. Demonstration of Submillimeter Astrophysics Technology at Caltech Submillimeter Observatory

    Data.gov (United States)

    National Aeronautics and Space Administration — Detector technology developments will determine the science product of future astrophysics missions and projects, and this is especially true at submillimeter...

  13. Plasma wave instability and amplification of terahertz radiation in field-effect-transistor arrays

    International Nuclear Information System (INIS)

    Popov, V V; Tsymbalov, G M; Shur, M S

    2008-01-01

    We show that the strong amplification of terahertz radiation takes place in an array of field-effect transistors at small DC drain currents due to hydrodynamic plasmon instability of the collective plasmon mode. Planar designs compatible with standard integrated circuit fabrication processes and strong coupling of terahertz radiation to plasmon modes in FET arrays make such arrays very attractive for potential applications in solid-state terahertz amplifiers and emitters

  14. Diode, transistor & fet circuits manual

    CERN Document Server

    Marston, R M

    2013-01-01

    Diode, Transistor and FET Circuits Manual is a handbook of circuits based on discrete semiconductor components such as diodes, transistors, and FETS. The book also includes diagrams and practical circuits. The book describes basic and special diode characteristics, heat wave-rectifier circuits, transformers, filter capacitors, and rectifier ratings. The text also presents practical applications of associated devices, for example, zeners, varicaps, photodiodes, or LEDs, as well as it describes bipolar transistor characteristics. The transistor can be used in three basic amplifier configuration

  15. High Magnetic Field in THz Plasma Wave Detection by High Electron Mobility Transistors

    Science.gov (United States)

    Sakowicz, M.; Łusakowski, J.; Karpierz, K.; Grynberg, M.; Valusis, G.

    The role of gated and ungated two dimensional (2D) electron plasma in THz detection by high electron mobility transistors (HEMTs) was investigated. THz response of GaAs/AlGaAs and GaN/AlGaN HEMTs was measured at 4.4K in quantizing magnetic fields with a simultaneous modulation of the gate voltage UGS. This allowed us to measure both the detection signal, S, and its derivative dS/dUGS. Shubnikov - de-Haas oscillations (SdHO) of both S and dS/dUGS were observed. A comparison of SdHO observed in detection and magnetoresistance measurements allows us to associate unambiguously SdHO in S and dS/dUGS with the ungated and gated parts of the transistor channel, respectively. This allows us to conclude that the entire channel takes part in the detection process. Additionally, in the case of GaAlAs/GaAs HEMTs, a structure related to the cyclotron resonance transition was observed.

  16. Submillimeter-wave and far-infrared spectroscopy of high-J transitions of the ground and ν2 = 1 states of ammonia.

    Science.gov (United States)

    Yu, Shanshan; Pearson, John C; Drouin, Brian J; Sung, Keeyoon; Pirali, Olivier; Vervloet, Michel; Martin-Drumel, Marie-Aline; Endres, Christian P; Shiraishi, Tetsuro; Kobayashi, Kaori; Matsushima, Fusakazu

    2010-11-07

    Complete and reliable knowledge of the ammonia spectrum is needed to enable the analysis and interpretation of astrophysical and planetary observations. Ammonia has been observed in the interstellar medium up to J=18 and more highly excited transitions are expected to appear in hot exoplanets and brown dwarfs. As a result, there is considerable interest in observing and assigning the high J (rovibrational) spectrum. In this work, numerous spectroscopic techniques were employed to study its high J transitions in the ground and ν(2)=1 states. Measurements were carried out using a frequency multiplied submillimeter spectrometer at Jet Propulsion Laboratory (JPL), a tunable far-infrared spectrometer at University of Toyama, and a high-resolution Bruker IFS 125 Fourier transform spectrometer (FTS) at Synchrotron SOLEIL. Highly excited ammonia was created with a radiofrequency discharge and a dc discharge, which allowed assignments of transitions with J up to 35. One hundred and seventy seven ground state and ν(2)=1 inversion transitions were observed with microwave accuracy in the 0.3-4.7 THz region. Of these, 125 were observed for the first time, including 26 ΔK=3 transitions. Over 2000 far-infrared transitions were assigned to the ground state and ν(2)=1 inversion bands as well as the ν(2) fundamental band. Of these, 1912 were assigned using the FTS data for the first time, including 222 ΔK=3 transitions. The accuracy of these measurements has been estimated to be 0.0003-0.0006 cm(-1). A reduced root mean square error of 0.9 was obtained for a global fit of the ground and ν(2)=1 states, which includes the lines assigned in this work and all previously available microwave, terahertz, far-infrared, and mid-infrared data. The new measurements and predictions reported here will support the analyses of astronomical observations by high-resolution spectroscopy telescopes such as Herschel, SOFIA, and ALMA. The comprehensive experimental rovibrational energy levels

  17. Instrumentation for Kinetic-Inductance-Detector-Based Submillimeter Radio Astronomy

    Science.gov (United States)

    Duan, Ran

    A substantial amount of important scientific information is contained within astronomical data at the submillimeter and far-infrared (FIR) wavelengths, including information regarding dusty galaxies, galaxy clusters, and star-forming regions; however, these wavelengths are among the least-explored fields in astronomy because of the technological difficulties involved in such research. Over the past 20 years, considerable efforts have been devoted to developing submillimeter- and millimeter-wavelength astronomical instruments and telescopes. The number of detectors is an important property of such instruments and is the subject of the current study. Future telescopes will require as many as hundreds of thousands of detectors to meet the necessary requirements in terms of the field of view, scan speed, and resolution. A large pixel count is one benefit of the development of multiplexable detectors that use kinetic inductance detector (KID) technology. This dissertation presents the development of a KID-based instrument including a portion of the millimeter-wave bandpass filters and all aspects of the readout electronics, which together enabled one of the largest detector counts achieved to date in submillimeter-/millimeter-wavelength imaging arrays: a total of 2304 detectors. The work presented in this dissertation has been implemented in the MUltiwavelength Submillimeter Inductance Camera (MUSIC), a new instrument for the Caltech Submillimeter Observatory (CSO).

  18. Next generation sub-millimeter wave focal plane array coupling concepts: an ESA TRP project to develop multichroic focal plane pixels for future CMB polarization experiments

    Science.gov (United States)

    Trappe, N.; Bucher, M.; De Bernardis, P.; Delabrouille, J.; Deo, P.; DePetris, M.; Doherty, S.; Ghribi, A.; Gradziel, M.; Kuzmin, L.; Maffei, B.; Mahashabde, S.; Masi, S.; Murphy, J. A.; Noviello, F.; O'Sullivan, C.; Pagano, L.; Piacentini, F.; Piat, M.; Pisano, G.; Robinson, M.; Stompor, R.; Tartari, A.; van der Vorst, M.; Verhoeve, P.

    2016-07-01

    The main objective of this activity is to develop new focal plane coupling array concepts and technologies that optimise the coupling from reflector optics to the large number of detectors for next generation sub millimetre wave telescopes particularly targeting measurement of the polarization of the cosmic microwave background (CMB). In this 18 month TRP programme the consortium are tasked with developing, manufacturing and experimentally verifying a prototype multichroic pixel which would be suitable for the large focal plane arrays which will be demanded to reach the required sensitivity of future CMB polarization missions. One major development was to have multichroic operation to potentially reduce the required focal plane size of a CMB mission. After research in the optimum telescope design and definition of requirements based on a stringent science case review, a number of compact focal plane architecture concepts were investigated before a pixel demonstrator consisting of a planar mesh lens feeding a backend Resonant Cold Electron Bolometer RCEB for filtering and detection of the dual frequency signal was planned for manufacture and test. In this demonstrator the frequencies of the channels was chosen to be 75 and 105 GHz in the w band close to the peak CMB signal. In the next year the prototype breadboards will be developed to test the beams produced by the manufactured flat lenses fed by a variety of antenna configurations and the spectral response of the RCEBs will also be verified.

  19. LDR: A submillimeter great observatory

    Science.gov (United States)

    Wilson, Robert

    1990-12-01

    The Large Deployable Reflector (LDR), a high Earth orbit free flying 10 to 20 m diameter deployable telescope, is described. The LDR is intended for use throughout the submillimeter band, using imaging receivers with unprecedented sensitivity and angular resolution. Its mission is to produce pictures of line emission regions in the solar neighborhood, in nearby galaxies and in objects at the edge of the known galaxy distribution. It is predicted to be an ideal instrument for exploring the first galaxies and protogalaxies as the submillimeter cooling lines should light up as soon as metals form.

  20. Calculation of the electron wave function in a graded-channel double-heterojunction modulation-doped field-effect transistor

    Science.gov (United States)

    Mui, D. S. L.; Patil, M. B.; Morkoc, H.

    1989-01-01

    Three double-heterojunction modulation-doped field-effect transistor structures with different channel composition are investigated theoretically. All of these transistors have an In(x)Ga(1-x)As channel sandwiched between two doped Al(0.3)Ga(0.7)As barriers with undoped spacer layers. In one of the structures, x varies from 0 from either heterojunction to 0.15 at the center of the channel quadratically; in the other two, constant values of x of 0 and 0.15 are used. The Poisson and Schroedinger equations are solved self-consistently for the electron wave function in all three cases. The results showed that the two-dimensional electron gas (2DEG) concentration in the channel of the quadratically graded structure is higher than the x = 0 one and slightly lower than the x = 0.15 one, and the mean distance of the 2DEG is closer to the center of the channel for this transistor than the other two. These two effects have important implications on the electron mobility in the channel.

  1. Submillimeter Array (SMA) Newsletter August 2011

    OpenAIRE

    Blundell, Raymond

    2011-01-01

    Submillimeter Array (SMA) Newsletter August 2011 Blundell, Raymond Submillimeter Array Newsletter | Number 12 | August 2011 CONTENTS 1 From the Director SCIENCE HIGHLIGHTS: 2 Faint Submillimeter Sources behind Massive Lensing Clusters 5 Millimeter Imaging of the β Pictoris Debris Disk: Evidence for a Planetesimal Belt 7 Physical Properties of the Circumnuclear Starburst Ring in the Barred Galaxy NGC1097 TECHNICAL HIGHLIGHTS: 9 ...

  2. Submillimeter heterodyne arrays for APEX

    NARCIS (Netherlands)

    Güsten, R.; Baryshev, A.; Bell, A.; Belloche, A.; Graf, U.; Hafok, H.; Heyminck, S.; Hochgürtel, S.; Honingh, C. E.; Jacobs, K.; Kasemann, C.; Klein, B.; Klein, T.; Korn, A.; Krämer, I.; Leinz, C.; Lundgren, A.; Menten, K. M.; Meyer, K.; Muders, D.; Pacek, F.; Rabanus, D.; Schäfer, F.; Schilke, P.; Schneider, G.; Stutzki, J.; Wieching, G.; Wunsch, A.; Wyrowski, F.

    2008-01-01

    We report on developments of submillimeter heterodyne arrays for high resolution spectroscopy with APEX. Shortly, we will operate state-of-the-art instruments in all major atmospheric windows accessible from Llano de Chajnantor. CHAMP+, a dual-color 2×7 element heterodyne array for operation in the

  3. Distributed amplifier using Josephson vortex flow transistors

    International Nuclear Information System (INIS)

    McGinnis, D.P.; Beyer, J.B.; Nordman, J.E.

    1986-01-01

    A wide-band traveling wave amplifier using vortex flow transistors is proposed. A vortex flow transistor is a long Josephson junction used as a current controlled voltage source. The dual nature of this device to the field effect transistor is exploited. A circuit model of this device is proposed and a distributed amplifier utilizing 50 vortex flow transistors is predicted to have useful gain to 100 GHz

  4. Transistor data book

    International Nuclear Information System (INIS)

    1988-03-01

    It introduces how to use this book. It lists transistor data and index, which are Type No, Cross index, Germanium PNP low power transistors, silicon NPN low power transistors, Germanium PNP high power transistors, Switching transistors, transistor arrays, Miscellaneous transistors, types with U.S military specifications, direct replacement transistors, suggested replacement transistors, schematic drawings, outline drawings, device number keys and manufacturer's logos.

  5. The Submillimeter Telescope (SMT) project

    International Nuclear Information System (INIS)

    Martin, R.N.; Baars, J.W.M.

    1990-01-01

    To exploit the potential of submillimeter astronomy, the Submillimeter Telescope (SMT) will be located at an altitude of 3178 meters on Emerald Peak 75 miles northeast of Tucson in Southern Arizona. The instrument is an altazimuth mounted f/13.8 Cassegrain homology telescope with two Nasmyth and bent Cassegrain foci. It will have diffraction limited performance at a wavelength of 300 microns and an operating overall figure accuracy of 15 microns rms. An important feature of the SMT is the construction of the primary and secondary reflectors out of aluminum-core CFRP face sheet sandwich panels, and the reflector backup structure and secondary support out of CFRP structural elements. This modern technology provides both a means for reaching the required precision of the SMT for both night and day operation (basically because of the low coefficient of thermal expansion and high strength-to-weight ratio of CFRP) and a potential route for the realization of lightweight telescopes of even greater accuracy in the future. The SMT will be the highest accuracy radio telescope ever built (at least a factor of 2 more accurate than existing telescopes). In addition, the SMT will be the first 10 m-class submillimeter telescope with a surface designed for efficient measurements at the important 350 microns wavelength atmospheric window. 9 refs

  6. Unijunction transistors

    International Nuclear Information System (INIS)

    1981-01-01

    The electrical characteristics of unijunction transistors can be modified by irradiation with electron beams in excess of 400 KeV and at a dose rate of 10 13 to 10 16 e/cm 2 . Examples are given of the effect of exposing the emitter-base junctions of transistors to such lattice defect causing radiation for a time sufficient to change the valley current of the transistor. (U.K.)

  7. SUBMILLIMETER LIGHTCURVES OF ASTEROIDS V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Submillimeter lightcurves of large asteroids Ceres, Davida, Io, Juno, Pallas, Vesta, and Victoria, observed at the Heinrich-Hertz Submillimeter Telescope from...

  8. Superconducting transistor

    International Nuclear Information System (INIS)

    Gray, K.E.

    1978-01-01

    A three film superconducting tunneling device, analogous to a semiconductor transistor, is presented, including a theoretical description and experimental results showing a current gain of four. Much larger current gains are shown to be feasible. Such a development is particularly interesting because of its novelty and the striking analogies with the semiconductor junction transistor

  9. PHOTOMETRIC REDSHIFTS OF SUBMILLIMETER GALAXIES

    International Nuclear Information System (INIS)

    Chakrabarti, Sukanya; Magnelli, Benjamin; Lutz, Dieter; Berta, Stefano; Popesso, Paola; McKee, Christopher F.; Pozzi, Francesca

    2013-01-01

    We use the photometric redshift method of Chakrabarti and McKee to infer photometric redshifts of submillimeter galaxies with far-IR (FIR) Herschel data obtained as part of the PACS Evolutionary Probe program. For the sample with spectroscopic redshifts, we demonstrate the validity of this method over a large range of redshifts (4 ∼> z ∼> 0.3) and luminosities, finding an average accuracy in (1 + z phot )/(1 + z spec ) of 10%. Thus, this method is more accurate than other FIR photometric redshift methods. This method is different from typical FIR photometric methods in deriving redshifts from the light-to-gas mass (L/M) ratio of infrared-bright galaxies inferred from the FIR spectral energy distribution, rather than dust temperatures. To assess the dependence of our photometric redshift method on the data in this sample, we contrast the average accuracy of our method when we use PACS data, versus SPIRE data, versus both PACS and SPIRE data. We also discuss potential selection effects that may affect the Herschel sample. Once the redshift is derived, we can determine physical properties of infrared-bright galaxies, including the temperature variation within the dust envelope, luminosity, mass, and surface density. We use data from the GOODS-S field to calculate the star formation rate density (SFRD) of submillimeter bright sources detected by AzTEC and PACS. The AzTEC-PACS sources, which have a threshold 850 μm flux ∼> 5 mJy, contribute 15% of the SFRD from all ultraluminous infrared galaxies (L IR ∼> 10 12 L ☉ ), and 3% of the total SFRD at z ∼ 2

  10. Transistor Effect in Improperly Connected Transistors.

    Science.gov (United States)

    Luzader, Stephen; Sanchez-Velasco, Eduardo

    1996-01-01

    Discusses the differences between the standard representation and a realistic representation of a transistor. Presents an experiment that helps clarify the explanation of the transistor effect and shows why transistors should be connected properly. (JRH)

  11. Report of the submillimeter splinter group

    Science.gov (United States)

    Harris, A. I.; Lequeux, J.

    1992-12-01

    The aim of the submillimeter splinter group of the LIST (Lunar Interferometry Study Team) was to examine the scientific and technical aspects of a submillimeter interferometer with an emphasis on heterodyne detection. The main elements of the scientific logic that lead to the conclusions that a heterodyne submillimeter array should have a collecting area of at order 1000 sq m are summarized. This conclusion is based on sensitivity constraints and the following points: anything that can be done from the ground, will be; an instrument as complex and expensive as a large submillimeter interferometer must be capable of significant extragalactic observations; and no matter what the future scientific trends are, looking at the main coolants will always be important. It is clear that an instrument of this size is several steps past the next generation of spaceborne observatories.

  12. Submillimeter Spectroscopic Study of Semiconductor Processing Plasmas

    Science.gov (United States)

    Helal, Yaser H.

    Plasmas used for manufacturing processes of semiconductor devices are complex and challenging to characterize. The development and improvement of plasma processes and models rely on feedback from experimental measurements. Current diagnostic methods are not capable of measuring absolute densities of plasma species with high resolution without altering the plasma, or without input from other measurements. At pressures below 100 mTorr, spectroscopic measurements of rotational transitions in the submillimeter/terahertz (SMM) spectral region are narrow enough in relation to the sparsity of spectral lines that absolute specificity of measurement is possible. The frequency resolution of SMM sources is such that spectral absorption features can be fully resolved. Processing plasmas are a similar pressure and temperature to the environment used to study astrophysical species in the SMM spectral region. Many of the molecular neutrals, radicals, and ions present in processing plasmas have been studied in the laboratory and their absorption spectra have been cataloged or are in the literature for the purpose of astrophysical study. Recent developments in SMM devices have made its technology commercially available for applications outside of specialized laboratories. The methods developed over several decades in the SMM spectral region for these laboratory studies are directly applicable for diagnostic measurements in the semiconductor manufacturing industry. In this work, a continuous wave, intensity calibrated SMM absorption spectrometer was developed as a remote sensor of gas and plasma species. A major advantage of intensity calibrated rotational absorption spectroscopy is its ability to determine absolute concentrations and temperatures of plasma species from first principles without altering the plasma environment. An important part of this work was the design of the optical components which couple 500 - 750 GHz radiation through a commercial inductively coupled plasma

  13. Dielectric Covered Planar Antennas at Submillimeter Wavelengths for Terahertz Imaging

    Science.gov (United States)

    Chattopadhyay, Goutam; Gill, John J.; Skalare, Anders; Lee, Choonsup; Llombart, Nuria; Siegel, Peter H.

    2011-01-01

    Most optical systems require antennas with directive patterns. This means that the physical area of the antenna will be large in terms of the wavelength. When non-cooled systems are used, the losses of microstrip or coplanar waveguide lines impede the use of standard patch or slot antennas for a large number of elements in a phased array format. Traditionally, this problem has been solved by using silicon lenses. However, if an array of such highly directive antennas is to be used for imaging applications, the fabrication of many closely spaced lenses becomes a problem. Moreover, planar antennas are usually fed by microstrip or coplanar waveguides while the mixer or the detector elements (usually Schottky diodes) are coupled in a waveguide environment. The coupling between the antenna and the detector/ mixer can be a fabrication challenge in an imaging array at submillimeter wavelengths. Antennas excited by a waveguide (TE10) mode makes use of dielectric superlayers to increase the directivity. These antennas create a kind of Fabry- Perot cavity between the ground plane and the first layer of dielectric. In reality, the antenna operates as a leaky wave mode where a leaky wave pole propagates along the cavity while it radiates. Thanks to this pole, the directivity of a small antenna is considerably enhanced. The antenna consists of a waveguide feed, which can be coupled to a mixer or detector such as a Schottky diode via a standard probe design. The waveguide is loaded with a double-slot iris to perform an impedance match and to suppress undesired modes that can propagate on the cavity. On top of the slot there is an air cavity and on top, a small portion of a hemispherical lens. The fractional bandwidth of such antennas is around 10 percent, which is good enough for heterodyne imaging applications.The new geometry makes use of a silicon lens instead of dielectric quarter wavelength substrates. This design presents several advantages when used in the submillimeter-wave

  14. Submillimeter Confocal Imaging Active Module

    Science.gov (United States)

    Hong, John; Mehdi, Imran; Siegel, Peter; Chattopadhyay, Goutam; Cwik, Thomas; Rowell, Mark; Hacker, John

    2009-01-01

    The term submillimeter confocal imaging active module (SCIAM) denotes a proposed airborne coherent imaging radar system that would be suitable for use in reconnaissance, surveillance, and navigation. The development of the SCIAM would include utilization and extension of recent achievements in monolithic microwave integrated circuits capable of operating at frequencies up to and beyond a nominal radio frequency of 340 GHz. Because the SCIAM would be primarily down-looking (in contradistinction to primarily side-looking), it could be useful for imaging shorter objects located between taller ones (for example, objects on streets between buildings). The SCIAM would utilize a confocal geometry to obtain high cross-track resolution, and would be amenable to synthetic-aperture processing of its output to obtain high along-track resolution. The SCIAM (see figure) would include multiple (two in the initial version) antenna apertures, separated from each other by a cross-track baseline of suitable length (e.g., 1.6 m). These apertures would both transmit the illuminating radar pulses and receive the returns. A common reference oscillator would generate a signal at a controllable frequency of (340 GHz + (Delta)f)/N, where (Delta)f is an instantaneous swept frequency difference and N is an integer. The output of this oscillator would be fed to a frequency- multiplier-and-power-amplifier module to obtain a signal, at 340 GHz + (Delta)f, that would serve as both the carrier signal for generating the transmitted pulses and a local-oscillator (LO) signal for a receiver associated with each antenna aperture. Because duplexers in the form of circulators or transmit/receive (T/R) switches would be lossy and extremely difficult to implement, the antenna apertures would be designed according to a spatial-diplexing scheme, in which signals would be coupled in and out via separate, adjacent transmitting and receiving feed horns. This scheme would cause the transmitted and received beams

  15. Interferometric investigation methods of plasma spatial characteristics on stellarators and tokamaks in submillimeter region

    International Nuclear Information System (INIS)

    Berezhnyj, V.L.; Kononenko, V.I.; Epishin, V.A.; Topkov, A.N.

    1992-01-01

    The review of interferometric methods of plasma investigation in the wave submillimeter range is given. The diagnostic schemes in stellarators and tokamaks designed for experienced thermonuclear reactors and also the perspective ones, which are still out of practice, are shown. The methods of these diagnostics, their physical principles, the main possibilities and restrictions at changes of electron density, magnetic fields (currents) and their spatial distributions are described. 105 refs.; 9 figs.; 2 tables. (author)

  16. Microwave, Millimeter, Submillimeter, and Far Infrared Spectral Databases

    Science.gov (United States)

    Pearson, J. C.; Pickett, H. M.; Drouin, B. J.; Chen, P.; Cohen, E. A.

    2002-01-01

    The spectrum of most known astrophysical molecules is derived from transitions between a few hundred to a few hundred thousand energy levels populated at room temperature. In the microwave and millimeter wave regions. spectroscopy is almost always performed with traditional microwave techniques. In the submillimeter and far infrared microwave technique becomes progressively more technologically challenging and infrared techniques become more widely employed as the wavelength gets shorter. Infrared techniques are typically one to two orders of magnitude less precise but they do generate all the strong features in the spectrum. With microwave technique, it is generally impossible and rarely necessary to measure every single transition of a molecular species, so careful fitting of quantum mechanical Hamiltonians to the transitions measured are required to produce the complete spectral picture of the molecule required by astronomers. The fitting process produces the most precise data possible and is required in the interpret heterodyne observations. The drawback of traditional microwave technique is that precise knowledge of the band origins of low lying excited states is rarely gained. The fitting of data interpolates well for the range of quantum numbers where there is laboratory data, but extrapolation is almost never precise. The majority of high resolution spectroscopic data is millimeter or longer in wavelength and a very limited number of molecules have ever been studied with microwave techniques at wavelengths shorter than 0.3 millimeters. The situation with infrared technique is similarly dire in the submillimeter and far infrared because the black body sources used are competing with a very significant thermal background making the signal to noise poor. Regardless of the technique used the data must be archived in a way useful for the interpretation of observations.

  17. Observing ice clouds in the submillimeter spectral range: the CloudIce mission proposal for ESA's Earth Explorer 8

    Directory of Open Access Journals (Sweden)

    S. A. Buehler

    2012-07-01

    Full Text Available Passive submillimeter-wave sensors are a way to obtain urgently needed global data on ice clouds, particularly on the so far poorly characterized "essential climate variable" ice water path (IWP and on ice particle size. CloudIce was a mission proposal to the European Space Agency ESA in response to the call for Earth Explorer 8 (EE8, which ran in 2009/2010. It proposed a passive submillimeter-wave sensor with channels ranging from 183 GHz to 664 GHz. The article describes the CloudIce mission proposal, with particular emphasis on describing the algorithms for the data-analysis of submillimeter-wave cloud ice data (retrieval algorithms and demonstrating their maturity. It is shown that we have a robust understanding of the radiative properties of cloud ice in the millimeter/submillimeter spectral range, and that we have a proven toolbox of retrieval algorithms to work with these data. Although the mission was not selected for EE8, the concept will be useful as a reference for other future mission proposals.

  18. Doped Organic Transistors.

    Science.gov (United States)

    Lüssem, Björn; Keum, Chang-Min; Kasemann, Daniel; Naab, Ben; Bao, Zhenan; Leo, Karl

    2016-11-23

    Organic field-effect transistors hold the promise of enabling low-cost and flexible electronics. Following its success in organic optoelectronics, the organic doping technology is also used increasingly in organic field-effect transistors. Doping not only increases device performance, but it also provides a way to fine-control the transistor behavior, to develop new transistor concepts, and even improve the stability of organic transistors. This Review summarizes the latest progress made in the understanding of the doping technology and its application to organic transistors. It presents the most successful doping models and an overview of the wide variety of materials used as dopants. Further, the influence of doping on charge transport in the most relevant polycrystalline organic semiconductors is reviewed, and a concise overview on the influence of doping on transistor behavior and performance is given. In particular, recent progress in the understanding of contact doping and channel doping is summarized.

  19. SOI Transistor measurement techniques using body contacted transistors

    International Nuclear Information System (INIS)

    Worley, E.R.; Williams, R.

    1989-01-01

    Measurements of body contacted SOI transistors are used to isolate parameters of the back channel and island edge transistor. Properties of the edge and back channel transistor have been measured before and after X-ray irradiation (ARACOR). The unique properties of the edge transistor are shown to be a result of edge geometry as confirmed by a two dimensional transistor simulator

  20. Pre-HEAT: submillimeter site testing and astronomical spectra from Dome A, Antarctica

    Science.gov (United States)

    Kulesa, C. A.; Walker, C. K.; Schein, M.; Golish, D.; Tothill, N.; Siegel, P.; Weinreb, S.; Jones, G.; Bardin, J.; Jacobs, K.; Martin, C. L.; Storey, J.; Ashley, M.; Lawrence, J.; Luong-Van, D.; Everett, J.; Wang, L.; Feng, L.; Zhu, Z.; Yan, J.; Yang, J.; Zhang, X.-G.; Cui, X.; Yuan, X.; Hu, J.; Xu, Z.; Jiang, Z.; Yang, H.; Li, Y.; Sun, B.; Qin, W.; Shang, Z.

    2008-07-01

    Pre-HEAT is a 20 cm aperture submillimeter-wave telescope with a 660 GHz (450 micron) Schottky diode heterodyne receiver and digital FFT spectrometer for the Plateau Observatory (PLATO) developed by the University of New South Wales. In January 2008 it was deployed to Dome A, the summit of the Antarctic plateau, as part of a scientific traverse led by the Polar Research Institute of China and the Chinese Academy of Sciences. Dome A may be one of the best sites in the world for ground based Terahertz astronomy, based on the exceptionally cold, dry and stable conditions which prevail there. Pre-HEAT is measuring the 450 micron sky opacity at Dome A and mapping the Galactic Plane in the 13CO J=6-5 line, constituting the first submillimeter measurements from Dome A. It is field-testing many of the key technologies for its namesake -- a successor mission called HEAT: the High Elevation Antarctic Terahertz telescope. Exciting prospects for submillimeter astronomy from Dome A and the status of Pre-HEAT will be presented.

  1. Plasma Wave Electronic Terahertz Technology

    National Research Council Canada - National Science Library

    Shur, Michael

    2003-01-01

    Plasma waves are oscillations of electron density in time and space. In deep submicron field effect transistors plasma wave frequencies lie in the terahertz range and can be tuned by applied gate bias...

  2. New technologies for the detection of millimeter and submillimeter waves

    Science.gov (United States)

    Richards, P. L.; Clarke, J.; Gildemeister, J. M.; Lanting, T.; Lee, A. T.

    2001-01-01

    Voltage-biased superconducting bolometers have many operational advantages over conventional bolometer technology including sensitivity, linearity, speed, and immunity from environmental disturbance. A review is given of the Berkeley program for developing this new technology. Developments include fully lithographed individual bolometers in the spiderweb configuration, arrays of 1024 close-packed absorber-coupled bolometers, antenna-coupled bolometers, and a frequency-domain SQUID (superconducting quantum interference device) readout multiplexer.

  3. Measurement of plasma conductivity using faraday rotation of submillimeter waves

    International Nuclear Information System (INIS)

    Kuzmenko, P.J.; Self, S.A.

    1983-01-01

    This paper examines the application of Faraday rotation to the measurement of electron combustion MHD plasmas. Details on the design of a working system are given, including the selection of operating wavelength. A theoretical comparison between the Faraday rotation technique and two-path interferometry shows Faraday rotation in its simplest form to be somewhat less sensitive to changes in electron concentration. This deficit can be balanced against greater immunity to vibration and thermal drift. Improved techniques of measuring the rotation angle promise greater sensitivity. A preliminary experiment has verified the technique

  4. Photon caliper to achieve submillimeter positioning accuracy

    Science.gov (United States)

    Gallagher, Kyle J.; Wong, Jennifer; Zhang, Junan

    2017-09-01

    The purpose of this study was to demonstrate the feasibility of using a commercial two-dimensional (2D) detector array with an inherent detector spacing of 5 mm to achieve submillimeter accuracy in localizing the radiation isocenter. This was accomplished by delivering the Vernier ‘dose’ caliper to a 2D detector array where the nominal scale was the 2D detector array and the non-nominal Vernier scale was the radiation dose strips produced by the high-definition (HD) multileaf collimators (MLCs) of the linear accelerator. Because the HD MLC sequence was similar to the picket fence test, we called this procedure the Vernier picket fence (VPF) test. We confirmed the accuracy of the VPF test by offsetting the HD MLC bank by known increments and comparing the known offset with the VPF test result. The VPF test was able to determine the known offset within 0.02 mm. We also cross-validated the accuracy of the VPF test in an evaluation of couch hysteresis. This was done by using both the VPF test and the ExacTrac optical tracking system to evaluate the couch position. We showed that the VPF test was in agreement with the ExacTrac optical tracking system within a root-mean-square value of 0.07 mm for both the lateral and longitudinal directions. In conclusion, we demonstrated the VPF test can determine the offset between a 2D detector array and the radiation isocenter with submillimeter accuracy. Until now, no method to locate the radiation isocenter using a 2D detector array has been able to achieve such accuracy.

  5. The Submillimeter Polarization of Sgr A*

    Energy Technology Data Exchange (ETDEWEB)

    Marrone, Daniel P [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Moran, James M [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Zhao, Jun-Hui [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Rao, Ramprasad [Inst. of Ast. and Astrophys., Academia Sinica, PO Box 23-141, Taipei 10617, Taiwan (China)

    2006-12-15

    We report on the submillimeter properties of Sgr A* derived from observations with the Submillimeter Array and its polarimeter. We ftid that the spectrum of Sgr A* between 230 and 690 GHz is slightly decreasing when measured simultaneously, indicating a transition to optically thin emission around 300-400 GHz. We also present very sensitive and well calibrated measurements of the polarization of Sgr A* at 230 and 345 GHz. With these data we are able to show for the frst time that the polarization of Sgr A* varies on hour timescales, as has been observed for the total intensity. On one night we fhd variability that may arise from a polarized 'blob' orbiting the black hole. Finally, we use the ensemble of observations to determine the rotation measure. This represents the frst statistically significant rotation measure determination and the only one made without resorting to comparing position angles measured at separate epochs. We frid a rotation measure of (-5.6 {+-} 0.7) x 10{sup 5} rad m{sup 2}, with no evidence for variability on inter-day timescales at the level of the measurement error. The stability constrains interday flictuations in the accretion rate to 8%. The mean intrinsic polarization position angle is 167{sup 0}{+-}7{sup 0} and we detect variations of 31{sup +18}{sub -9} degrees. This separation of intrinsic polarization changes and possible rotation measure flictuations is now possible because of the frequency coverage and sensitivity of our data. The observable rotation measure restricts the accretion rate to the range 2 x 10{sup -7} M o-dot yr{sup -1} to 2 x 10{sup -9} M o-dot yr{sup -1}, if the magnetic field is near equipartition and ordered.

  6. The Submillimeter Polarization of Sgr A*

    International Nuclear Information System (INIS)

    Marrone, Daniel P; Moran, James M; Zhao, Jun-Hui; Rao, Ramprasad

    2006-01-01

    We report on the submillimeter properties of Sgr A* derived from observations with the Submillimeter Array and its polarimeter. We ftid that the spectrum of Sgr A* between 230 and 690 GHz is slightly decreasing when measured simultaneously, indicating a transition to optically thin emission around 300-400 GHz. We also present very sensitive and well calibrated measurements of the polarization of Sgr A* at 230 and 345 GHz. With these data we are able to show for the frst time that the polarization of Sgr A* varies on hour timescales, as has been observed for the total intensity. On one night we fhd variability that may arise from a polarized 'blob' orbiting the black hole. Finally, we use the ensemble of observations to determine the rotation measure. This represents the frst statistically significant rotation measure determination and the only one made without resorting to comparing position angles measured at separate epochs. We frid a rotation measure of (-5.6 ± 0.7) x 10 5 rad m 2 , with no evidence for variability on inter-day timescales at the level of the measurement error. The stability constrains interday flictuations in the accretion rate to 8%. The mean intrinsic polarization position angle is 167 0 ±7 0 and we detect variations of 31 +18 -9 degrees. This separation of intrinsic polarization changes and possible rotation measure flictuations is now possible because of the frequency coverage and sensitivity of our data. The observable rotation measure restricts the accretion rate to the range 2 x 10 -7 M o-dot yr -1 to 2 x 10 -9 M o-dot yr -1 , if the magnetic field is near equipartition and ordered

  7. The Submillimeter Polarization of Sgr A*

    Science.gov (United States)

    Marrone, Daniel P.; Moran, James M.; Zhao, Jun-Hui; Rao, Ramprasad

    2006-12-01

    We report on the submillimeter properties of Sgr A* derived from observations with the Submillimeter Array and its polarimeter. We ftid that the spectrum of Sgr A* between 230 and 690 GHz is slightly decreasing when measured simultaneously, indicating a transition to optically thin emission around 300 400 GHz. We also present very sensitive and well calibrated measurements of the polarization of Sgr A* at 230 and 345 GHz. With these data we are able to show for the frst time that the polarization of Sgr A* varies on hour timescales, as has been observed for the total intensity. On one night we fhd variability that may arise from a polarized "blob" orbiting the black hole. Finally, we use the ensemble of observations to determine the rotation measure. This represents the frst statistically significant rotation measure determination and the only one made without resorting to comparing position angles measured at separate epochs. We frid a rotation measure of (-5.6 ± 0.7) × 105 rad m2, with no evidence for variability on inter-day timescales at the level of the measurement error. The stability constrains interday flictuations in the accretion rate to 8%. The mean intrinsic polarization position angle is 167°±7° and we detect variations of 31+18-9 degrees. This separation of intrinsic polarization changes and possible rotation measure flictuations is now possible because of the frequency coverage and sensitivity of our data. The observable rotation measure restricts the accretion rate to the range 2 × 10-7 Mdot o yr-1 to 2 × 10-9 Mdot o yr-1, if the magnetic ffeld is near equipartition and ordered.

  8. Dual-Mode Gas Sensor Composed of a Silicon Nanoribbon Field Effect Transistor and a Bulk Acoustic Wave Resonator: A Case Study in Freons

    Directory of Open Access Journals (Sweden)

    Ye Chang

    2018-01-01

    Full Text Available In this paper, we develop a novel dual-mode gas sensor system which comprises a silicon nanoribbon field effect transistor (Si-NR FET and a film bulk acoustic resonator (FBAR. We investigate their sensing characteristics using polar and nonpolar organic compounds, and demonstrate that polarity has a significant effect on the response of the Si-NR FET sensor, and only a minor effect on the FBAR sensor. In this dual-mode system, qualitative discrimination can be achieved by analyzing polarity with the Si-NR FET and quantitative concentration information can be obtained using a polymer-coated FBAR with a detection limit at the ppm level. The complementary performance of the sensing elements provides higher analytical efficiency. Additionally, a dual mixture of two types of freons (CFC-113 and HCFC-141b is further analyzed with the dual-mode gas sensor. Owing to the small size and complementary metal-oxide semiconductor (CMOS-compatibility of the system, the dual-mode gas sensor shows potential as a portable integrated sensing system for the analysis of gas mixtures in the future.

  9. Black Holes and Sub-millimeter Dimensions

    CERN Document Server

    Argyres, Philip C; March-Russell, John David; Argyres, Philip C.; Dimopoulos, Savas; March-Russell, John

    1998-01-01

    Recently, a new framework for solving the hierarchy problem was proposed which does not rely on low energy supersymmetry or technicolor. The fundamental Planck mass is at a TeV and the observed weakness of gravity at long distances is due the existence of new sub-millimeter spatial dimensions. In this letter, we study how the properties of black holes are altered in these theories. Small black holes---with Schwarzschild radii smaller than the size of the new spatial dimensions---are quite different. They are bigger, colder, and longer-lived than a usual $(3+1)$-dimensional black hole of the same mass. Furthermore, they primarily decay into harmless bulk graviton modes rather than standard-model degrees of freedom. We discuss the interplay of our scenario with the holographic principle. Our results also have implications for the bounds on the spectrum of primordial black holes (PBHs) derived from the photo-dissociation of primordial nucleosynthesis products, distortion of the diffuse gamma-ray spectrum, overcl...

  10. Submillimeter heterodyne receiver for the CSO telescope

    International Nuclear Information System (INIS)

    Gulkis, S.

    1988-01-01

    This task is to build a cryogenically cooled 620 to 700 GHz astronomical receiver that will be used as a facility instrument at the CalTech Submillimeter Observatory (CSO) on Mauna Kea, Hawaii. The receiver will have applications as a very high resolution spectrometer to investigate spectral lines in planetary and satellite atmospheres, and comets. The receiver will also be used to make continuum measurements of planets, satellites, and asteroids. During FY88, a scale model (200 GHz) SIS mixer radiometer was built and intrgrated into a cryostat designed for use on the CSO telescope. This system will serve as a model to guide the work on the higher frequency mixer. A solid state local oscillator source that covers two bands in the 600 to 700 GHz has been developed under contract JPL and will be delivered before the end of the year. Work has continued on the SIS materials needed for the 620 to 700 GHz mixer. Test hardware has been developed which allow the 1 to 5 curves for SIS material to be easily measured

  11. Ionoacoustic characterization of the proton Bragg peak with submillimeter accuracy

    Energy Technology Data Exchange (ETDEWEB)

    Assmann, W., E-mail: walter.assmann@lmu.de; Reinhardt, S.; Lehrack, S.; Edlich, A.; Thirolf, P. G.; Parodi, K. [Department for Medical Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, Garching 85748 (Germany); Kellnberger, S.; Omar, M.; Ntziachristos, V. [Institute for Biological and Medical Imaging, Technische Universität München and Helmholtz Zentrum München, Ingolstädter Landstrasse 1, Neuherberg 85764 (Germany); Moser, M.; Dollinger, G. [Institute for Applied Physics and Measurement Technology, Universität der Bundeswehr, Werner-Heisenberg-Weg 39, Neubiberg 85577 (Germany)

    2015-02-15

    Purpose: Range verification in ion beam therapy relies to date on nuclear imaging techniques which require complex and costly detector systems. A different approach is the detection of thermoacoustic signals that are generated due to localized energy loss of ion beams in tissue (ionoacoustics). Aim of this work was to study experimentally the achievable position resolution of ionoacoustics under idealized conditions using high frequency ultrasonic transducers and a specifically selected probing beam. Methods: A water phantom was irradiated by a pulsed 20 MeV proton beam with varying pulse intensity and length. The acoustic signal of single proton pulses was measured by different PZT-based ultrasound detectors (3.5 and 10 MHz central frequencies). The proton dose distribution in water was calculated by Geant4 and used as input for simulation of the generated acoustic wave by the matlab toolbox k-WAVE. Results: In measurements from this study, a clear signal of the Bragg peak was observed for an energy deposition as low as 10{sup 12} eV. The signal amplitude showed a linear increase with particle number per pulse and thus, dose. Bragg peak position measurements were reproducible within ±30 μm and agreed with Geant4 simulations to better than 100 μm. The ionoacoustic signal pattern allowed for a detailed analysis of the Bragg peak and could be well reproduced by k-WAVE simulations. Conclusions: The authors have studied the ionoacoustic signal of the Bragg peak in experiments using a 20 MeV proton beam with its correspondingly localized energy deposition, demonstrating submillimeter position resolution and providing a deep insight in the correlation between the acoustic signal and Bragg peak shape. These results, together with earlier experiments and new simulations (including the results in this study) at higher energies, suggest ionoacoustics as a technique for range verification in particle therapy at locations, where the tumor can be localized by ultrasound

  12. Science with the wideband Submillimeter Array: A Strategy for the Decade 2017-2027

    Science.gov (United States)

    Wilner, D.; Keto, E.; Bower, G.; Ching, T. C.; Gurwell, M.; Hirano, N.; Keating, G.; Lai, S. P.; Patel, N.; Petitpas, G.; Qi, C.; Sridharan, T. K.; Urata, Y.; Young, K.; Zhang, Q.; Zhao, J.-H.

    2017-01-01

    of evolved star envelopes, the constituents of planetary atmospheres, starburst galaxies in the local Universe and at high redshifts, and even low-mass galaxies at high redshifts through the technique of intensity mapping. The wSMA speeds up observations to allow systematic, comparative studies of large numbers of spectral surveys for the first time. The wSMA also will be ideally suited for the study of sources in the time domain. Illustrative examples include the variability of the accretion flow onto the SgrA* black hole, capturing emission from gamma ray bursts from massive star deaths in the early universe and the mergers of compact objects that produce gravitational waves, and resolved spectroscopy of the pristine material that escapes from comets as they traverse the inner Solar System. The wSMA will be complementary to the larger international Atacama Large Millimeter/ submillimeter Array (ALMA) in Chile, which followed the SMA into submillimeter interferometry in 2011. The immense time pressure on ALMA from its many constituencies only creates an increasing need for the wSMA, notably for the large class of observations that do not require ALMA's full sensitivity or angular resolution, as well as for unique submillimeter access to the northern sky. The wSMA will play a leading role in select science areas in the ALMA era, including those requiring long-term programs to build large samples, or rapid response based on flexible scheduling, as well as for high risk seed studies specifically designed for subsequent ALMA follow-up. In addition, the wSMA will be a critical station for submillimeter VLBI observations of supermassive black holes in the global Event Horizon Telescope, which will be bolstered by the inclusion of ALMA in 2017. Finally, the wSMA design explicitly incorporates open space for additional instrumentation to pursue new and compelling science goals and technical innovations, continuing its role as a pathfinder for submillimeter astronomy.

  13. Submillimeter medical imaging in emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lang, C.; Thirolf, P.G. [LMU, Muenchen (Germany); Habs, D. [LMU, Muenchen (Germany); MPQ, Garching (Germany); Zoglauer, A. [SSL, Berkeley (United States)

    2012-07-01

    We present a nuclear medical imaging technique, capable to reach submillimeter spatial resolution in 3 dimensions with a short exposure time and a low radioactive dose compared to conventional PET. This '{gamma}-PET' technique takes advantage of specific e{sup +} sources which simultaneously with the {beta}{sup +} decay emit an additional photon. Exploiting the triple coincidence between the positron annihilation and the additional emitted {gamma}, it is possible to separate the reconstructed 'true' events from background. Thus the spatial uncertainty introduced by the motion of the e{sup +} or by Compton scattering within the patient can be strongly reduced in the direction normal to the annihilation. MC-simulations and image reconstruction studies have been performed using the library MEGAlib, which we modified to realize an event reconstruction using the {beta}{sup +}{gamma} coincidences. The simulated geometry consists of 4 LaBr{sub 3} scintillator crystals (5 x 5 x 3 cm{sup 3}) read out by a 2D-segmented photomultiplier (64 pixels, each 6 x 6 mm{sup 2}) and 4 double-sided silicon strip detectors (each with 2 x 128 strips, active area of 5 x 5 cm{sup 2}, thickness 0.5 mm), positioned around an H{sub 2}O sphere of 6 cm diameter. Inside are two {sup 22}Na point-like test sources, placed at a distance of 0.4 mm. The resolution results in 0.2 mm (FWHM) in each direction, surpassing the performance of conventional PET by about an order of magnitude.

  14. Wave

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo

    2008-01-01

    Estimates for the amount of potential wave energy in the world range from 1-10 TW. The World Energy Council estimates that a potential 2TW of energy is available from the world’s oceans, which is the equivalent of twice the world’s electricity production. Whilst the recoverable resource is many...... times smaller it remains very high. For example, whilst there is enough potential wave power off the UK to supply the electricity demands several times over, the economically recoverable resource for the UK is estimated at 25% of current demand; a lot less, but a very substantial amount nonetheless....

  15. Silicon heterojunction transistor

    International Nuclear Information System (INIS)

    Matsushita, T.; Oh-uchi, N.; Hayashi, H.; Yamoto, H.

    1979-01-01

    SIPOS (Semi-insulating polycrystalline silicon) which is used as a surface passivation layer for highly reliable silicon devices constitutes a good heterojunction for silicon. P- or B-doped SIPOS has been used as the emitter material of a heterojunction transistor with the base and collector of silicon. An npn SIPOS-Si heterojunction transistor showing 50 times the current gain of an npn silicon homojunction transistor has been realized by high-temperature treatments in nitrogen and low-temperature annealing in hydrogen or forming gas

  16. Tracing Magnetic Fields With The Polarization Of Submillimeter Lines

    Science.gov (United States)

    Zhang, Heshou; Yan, Huirong

    2017-10-01

    Magnetic fields play important roles in many astrophysical processes. However, there is no universal diagnostic for the magnetic fields in the interstellar medium (ISM) and each magnetic tracer has its limitation. Any new detection method is thus valuable. Theoretical studies have shown that submillimeter fine-structure lines are polarized due to atomic alignment by Ultraviolet (UV) photon-excitation, which opens up a new avenue to probe interstellar magnetic fields. The method is applicable to all radiative-excitation dominant region, e.g., H II Regions, PDRs. The polarization of the submillimeter fine-structure lines induced by atomic alignment could be substantial and the applicability of using the spectro-polarimetry of atomic lines to trace magnetic fields has been supported by synthetic observations of simulated ISM in our recent paper. Our results demonstrate that the polarization of submillimeter atomic lines is a powerful magnetic tracer and add great value to the observational studies of the submilimeter astronomy.

  17. Silicon nanowire transistors

    CERN Document Server

    Bindal, Ahmet

    2016-01-01

    This book describes the n and p-channel Silicon Nanowire Transistor (SNT) designs with single and dual-work functions, emphasizing low static and dynamic power consumption. The authors describe a process flow for fabrication and generate SPICE models for building various digital and analog circuits. These include an SRAM, a baseband spread spectrum transmitter, a neuron cell and a Field Programmable Gate Array (FPGA) platform in the digital domain, as well as high bandwidth single-stage and operational amplifiers, RF communication circuits in the analog domain, in order to show this technology’s true potential for the next generation VLSI. Describes Silicon Nanowire (SNW) Transistors, as vertically constructed MOS n and p-channel transistors, with low static and dynamic power consumption and small layout footprint; Targets System-on-Chip (SoC) design, supporting very high transistor count (ULSI), minimal power consumption requiring inexpensive substrates for packaging; Enables fabrication of different types...

  18. Organic electrochemical transistors

    KAUST Repository

    Rivnay, Jonathan; Inal, Sahika; Salleo, Alberto; Owens, Ró isí n M.; Berggren, Magnus; Malliaras, George G.

    2018-01-01

    Organic electrochemical transistors (OECTs) make effective use of ion injection from an electrolyte to modulate the bulk conductivity of an organic semiconductor channel. The coupling between ionic and electronic charges within the entire volume

  19. Vertical organic transistors.

    Science.gov (United States)

    Lüssem, Björn; Günther, Alrun; Fischer, Axel; Kasemann, Daniel; Leo, Karl

    2015-11-11

    Organic switching devices such as field effect transistors (OFETs) are a key element of future flexible electronic devices. So far, however, a commercial breakthrough has not been achieved because these devices usually lack in switching speed (e.g. for logic applications) and current density (e.g. for display pixel driving). The limited performance is caused by a combination of comparatively low charge carrier mobilities and the large channel length caused by the need for low-cost structuring. Vertical Organic Transistors are a novel technology that has the potential to overcome these limitations of OFETs. Vertical Organic Transistors allow to scale the channel length of organic transistors into the 100 nm regime without cost intensive structuring techniques. Several different approaches have been proposed in literature, which show high output currents, low operation voltages, and comparatively high speed even without sub-μm structuring technologies. In this review, these different approaches are compared and recent progress is highlighted.

  20. Diagnostics from three rising submillimeter bursts

    International Nuclear Information System (INIS)

    Zhou, Ai-Hua; Li, Jian-Ping; Wang, Xin-Dong

    2016-01-01

    In this paper we investigate three novel rising submillimeter (THz) bursts that occurred sequentially in Super Active Region NOAA 10486. The average rising rate of the flux density above 200 GHz is only 20 sfu GHz −1 (corresponding to spectral index α of 1.6) for the THz spectral components of the 2003 October 28 and November 4 bursts, but it attained values of 235 sfu GHz −1 (α = 4.8) in the 2003 November 2 burst. The steeply rising THz spectrum can be produced by a population of highly relativistic electrons with a low-energy cutoff of 1 MeV, but it only requires a low-energy cutoff of 30 keV for the two slowly rising THz bursts, via gyrosynchrotron (GS) radiation based on our numerical simulations of burst spectra in the magnetic dipole field case. The electron density variation is much larger in the THz source than in the microwave (MW) source. It is interesting that the THz source radius decreased by 20%–50% during the decay phase for the three events, but the MW source increased by 28% for the 2003 November 2 event. In the paper we will present a formula that can be used to calculate the energy released by ultrarelativistic electrons, taking the relativistic correction into account for the first time. We find that the energy released by energetic electrons in the THz source exceeds that in the MW source due to the strong GS radiation loss in the THz range, although the modeled THz source area is 3–4 orders smaller than the modeled MW source one. The total energies released by energetic electrons via the GS radiation in radio sources are estimated, respectively, to be 5.2 × 10 33 , 3.9 × 10 33 and 3.7 × 10 32 erg for the October 28, November 2 and 4 bursts, which are 131, 76 and 4 times as large as the thermal energies of 2.9 × 10 31 , 2.1 × 10 31 and 5.2 × 10 31 erg estimated from soft X-ray GOES observations. (paper)

  1. Submillimeter (Lambda < 1 mm) Continuum Imaging at CSO: A Retrospective

    Science.gov (United States)

    Dowell, C. Darren

    2009-01-01

    This contribution is submitted on behalf of all students, postdocs, and staff inspired and supported by Tom Phillips to build an instrument and then wait for low precipitable water vapor. Over the 20 plus years of its existence, the Caltech Submillimeter Observatory (CSO) has seen a succession of ever more powerful detectors to measure continuum emission in the shortest submillimeter bands available from Mauna Kea. These instruments have been trained on the nearest solar systems, the most distant galaxies, and objects in between. I show several images collected over the 5 plus year history of the SHARC II camera and anecdotal comparison with past work.

  2. Development Of A Multicolor Sub/millimeter Camera Using Microwave Kinetic Inductance Detectors

    Science.gov (United States)

    Schlaerth, James A.; Czakon, N. G.; Day, P. K.; Downes, T. P.; Duan, R.; Glenn, J.; Golwala, S. R.; Hollister, M. I.; LeDuc, H. G.; Maloney, P. R.; Mazin, B. A.; Noroozian, O.; Sayers, J.; Siegel, S.; Vayonakis, A.; Zmuidzinas, J.

    2011-01-01

    Microwave Kinetic Inductance Detectors (MKIDs) are superconducting resonators useful for detecting light from the millimeter-wave to the X-ray. These detectors are easily multiplexed, as the resonances can be tuned to slightly different frequencies, allowing hundreds of detectors to be read out simultaneously using a single feedline. The Multicolor Submillimeter Inductance Camera, MUSIC, will use 2304 antenna-coupled MKIDs in multicolor operation, with bands centered at wavelengths of 0.85, 1.1, 1.3 and 2.0 mm, beginning in 2011. Here we present the results of our demonstration instrument, DemoCam, containing a single 3-color array with 72 detectors and optics similar to MUSIC. We present sensitivities achieved at the telescope, and compare to those expected based upon laboratory tests. We explore the factors that limit the sensitivity, in particular electronics noise, antenna efficiency, and excess loading. We discuss mitigation of these factors, and how we plan to improve sensitivity to the level of background-limited performance for the scientific operation of MUSIC. Finally, we note the expected mapping speed and contributions of MUSIC to astrophysics, and in particular to the study of submillimeter galaxies. This research has been funded by grants from the National Science Foundation, the Gordon and Betty Moore Foundation, and the NASA Graduate Student Researchers Program.

  3. Tunable submillimeter sources applied to the excited state rotational spectroscopy and kinetics of CH3F

    International Nuclear Information System (INIS)

    Blumberg, W.A.M.; Fetterman, H.R.; Peck, D.D.; Goldsmith, P.F.

    1979-01-01

    Tunable submillimeter radiation, generated and detected using optically pumped lasers and Schottky diode mixers, has been used in an infrared-submillimeter double resonance investigation of CH 3 F. This technique permits the direct observation of the molecular rotational spectra and kinetics of excited vibrational states and is particularly important for those molecules which are candidates for optically pumped submillimeter lasers

  4. Submillimetre-wave astronomy

    International Nuclear Information System (INIS)

    Beckman, J.E.; Phillips, J.P.

    1982-01-01

    Observations in the 100-1000-micron band and the instruments used to obtain them are discussed in contributions to the Submillimeter Wave Astronomy Conference held at Queen Mary College, London, in September 1981. The major subject areas covered are large-scale structure and radiative transfer within interstellar clouds, spectroscopic observations of molecular sources, interstellar chemistry, and submillimeter (SM) instrumentation. Reports are included on the formation of giant cloud complexes, cool molecular clouds, models for hot-centered and externally heated clouds, dust in Bok globules, airborne FIR and SM spectroscopy, rotational transitions of CH3OH and NH2 near 1.2 mm, high-velocity flows and molecular jets, FIR emissions from late-type galaxies, ion-grain collisions as a source of interstellar molecules, bandpass filters for SM astronomy, the SM receiver of the future, HF techniques in heterodyne astronomy, and the mm-wave cosmic background

  5. Electron irradiation of power transistors

    International Nuclear Information System (INIS)

    Hower, P.L.; Fiedor, R.J.

    1982-01-01

    A method for reducing storage time and gain parameters in a semiconductor transistor includes the step of subjecting the transistor to electron irradiation of a dosage determined from measurements of the parameters of a test batch of transistors. Reduction of carrier lifetime by proton bombardment and gold doping is mentioned as an alternative to electron irradiation. (author)

  6. Submillimeter laboratory identification of CH{sup +} and CH{sub 2}D{sup +}

    Energy Technology Data Exchange (ETDEWEB)

    Amano, T. [Department of Chemistry and Department of Physics and Astronomy, University of Waterloo, Waterloo, ON N2L 3G1 (Canada)

    2015-01-22

    Laboratory identification of two basic and important interstellar molecular ions is presented. The J = 1 - 0 rotational transition of {sup 12}CH{sup +} together with those of {sup 13}CH{sup +} and {sup 12}CD{sup +} was observed in the laboratory. The newly obtained frequencies were found to be different from those reported previously. Various experimental evidences firmly support the new measurements. In addition, the Zeeman effect and the spin-rotation hyperfine interaction enforce the laboratory identification with no ambiguity. Rotational lines of CH{sub 2}D{sup +} were observed in the submillimeter-wave region. This laboratory observation is consistent with a recent tentative identification of CH{sub 2}D{sup +} toward Ori IRc2.

  7. Optics for MUSIC: a new (sub)millimeter camera for the Caltech Submillimeter Observatory

    Science.gov (United States)

    Sayers, Jack; Czakon, Nicole G.; Day, Peter K.; Downes, Thomas P.; Duan, Ran P.; Gao, Jiansong; Glenn, Jason; Golwala, Sunil R.; Hollister, Matt I.; LeDuc, Henry G.; Mazin, Benjamin A.; Maloney, Philip R.; Noroozian, Omid; Nguyen, Hien T.; Schlaerth, James A.; Siegel, Seth; Vaillancourt, John E.; Vayonakis, Anastasios; Wilson, Philip R.; Zmuidzinas, Jonas

    2010-07-01

    We will present the design and implementation, along with calculations and some measurements of the performance, of the room-temperature and cryogenic optics for MUSIC, a new (sub)millimeter camera we are developing for the Caltech Submm Observatory (CSO). The design consists of two focusing elements in addition to the CSO primary and secondary mirrors: a warm off-axis elliptical mirror and a cryogenic (4K) lens. These optics will provide a 14 arcmin field of view that is diffraction limited in all four of the MUSIC observing bands (2.00, 1.33, 1.02, and 0.86 mm). A cold (4K) Lyot stop will be used to define the primary mirror illumination, which will be maximized while keeping spillover at the sub 1% level. The MUSIC focal plane will be populated with broadband phased antenna arrays that efficiently couple to factor of (see manuscript) 3 in bandwidth,1, 2 and each pixel on the focal plane will be read out via a set of four lumped element filters that define the MUSIC observing bands (i.e., each pixel on the focal plane simultaneously observes in all four bands). Finally, a series of dielectric and metal-mesh low pass filters have been implemented to reduce the optical power load on the MUSIC cryogenic stages to a quasi-negligible level while maintaining good transmission in-band.

  8. [Comparative study of effect of infrared, submillimeter, and millimeter electromagnetic radiation on wing somatic mutations in Drosophila melanogaster induced by gamma-irradiation].

    Science.gov (United States)

    Fedorov, V I; Pogodin, A S; Dubatolova, T D; Varlamov, A V; Leont'ev, K V; Khamoian, A G

    2001-01-01

    It was shown that the number of spontaneous and gamma-radiation-induced somatic mutations in wing cells of fruit flies (third instar larvae) exposed to laser irradiation of submillimeter range (lambda = 81.5 microns) was significantly lower than in control. Laser irradiation did not affect the number of recombinations. Exposure to laser radiation in the infrared range and electromagnetic waves of the millimeter range (lambda = 3.8 mm) enhanced the effect of gamma-irradiation.

  9. Accelerating the life of transistors

    International Nuclear Information System (INIS)

    Qi Haochun; Lü Changzhi; Zhang Xiaoling; Xie Xuesong

    2013-01-01

    Choosing small and medium power switching transistors of the NPN type in a 3DK set as the study object, the test of accelerating life is conducted in constant temperature and humidity, and then the data are statistically analyzed with software developed by ourselves. According to degradations of such sensitive parameters as the reverse leakage current of transistors, the lifetime order of transistors is about more than 10 4 at 100 °C and 100% relative humidity (RH) conditions. By corrosion fracture of transistor outer leads and other failure modes, with the failure truncated testing, the average lifetime rank of transistors in different distributions is extrapolated about 10 3 . Failure mechanism analyses of degradation of electrical parameters, outer lead fracture and other reasons that affect transistor lifetime are conducted. The findings show that the impact of external stress of outer leads on transistor reliability is more serious than that of parameter degradation. (semiconductor devices)

  10. Vertical organic transistors

    International Nuclear Information System (INIS)

    Lüssem, Björn; Günther, Alrun; Fischer, Axel; Kasemann, Daniel; Leo, Karl

    2015-01-01

    Organic switching devices such as field effect transistors (OFETs) are a key element of future flexible electronic devices. So far, however, a commercial breakthrough has not been achieved because these devices usually lack in switching speed (e.g. for logic applications) and current density (e.g. for display pixel driving). The limited performance is caused by a combination of comparatively low charge carrier mobilities and the large channel length caused by the need for low-cost structuring. Vertical Organic Transistors are a novel technology that has the potential to overcome these limitations of OFETs. Vertical Organic Transistors allow to scale the channel length of organic transistors into the 100 nm regime without cost intensive structuring techniques. Several different approaches have been proposed in literature, which show high output currents, low operation voltages, and comparatively high speed even without sub-μm structuring technologies. In this review, these different approaches are compared and recent progress is highlighted. (topical review)

  11. Photosensitive graphene transistors.

    Science.gov (United States)

    Li, Jinhua; Niu, Liyong; Zheng, Zijian; Yan, Feng

    2014-08-20

    High performance photodetectors play important roles in the development of innovative technologies in many fields, including medicine, display and imaging, military, optical communication, environment monitoring, security check, scientific research and industrial processing control. Graphene, the most fascinating two-dimensional material, has demonstrated promising applications in various types of photodetectors from terahertz to ultraviolet, due to its ultrahigh carrier mobility and light absorption in broad wavelength range. Graphene field effect transistors are recognized as a type of excellent transducers for photodetection thanks to the inherent amplification function of the transistors, the feasibility of miniaturization and the unique properties of graphene. In this review, we will introduce the applications of graphene transistors as photodetectors in different wavelength ranges including terahertz, infrared, visible, and ultraviolet, focusing on the device design, physics and photosensitive performance. Since the device properties are closely related to the quality of graphene, the devices based on graphene prepared with different methods will be addressed separately with a view to demonstrating more clearly their advantages and shortcomings in practical applications. It is expected that highly sensitive photodetectors based on graphene transistors will find important applications in many emerging areas especially flexible, wearable, printable or transparent electronics and high frequency communications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Monolithic acoustic graphene transistors based on lithium niobate thin film

    Science.gov (United States)

    Liang, J.; Liu, B.-H.; Zhang, H.-X.; Zhang, H.; Zhang, M.-L.; Zhang, D.-H.; Pang, W.

    2018-05-01

    This paper introduces an on-chip acoustic graphene transistor based on lithium niobate thin film. The graphene transistor is embedded in a microelectromechanical systems (MEMS) acoustic wave device, and surface acoustic waves generated by the resonator induce a macroscopic current in the graphene due to the acousto-electric (AE) effect. The acoustic resonator and the graphene share the lithium niobate film, and a gate voltage is applied through the back side of the silicon substrate. The AE current induced by the Rayleigh and Sezawa modes was investigated, and the transistor outputs a larger current in the Rayleigh mode because of a larger coupling to velocity ratio. The output current increases linearly with the input radiofrequency power and can be effectively modulated by the gate voltage. The acoustic graphene transistor realized a five-fold enhancement in the output current at an optimum gate voltage, outperforming its counterpart with a DC input. The acoustic graphene transistor demonstrates a paradigm for more-than-Moore technology. By combining the benefits of MEMS and graphene circuits, it opens an avenue for various system-on-chip applications.

  13. 350 μm POLARIMETRY FROM THE CALTECH SUBMILLIMETER OBSERVATORY

    International Nuclear Information System (INIS)

    Dotson, Jessie L.; Vaillancourt, John E.; Kirby, Larry; Hildebrand, Roger H.; Dowell, C. Darren; Davidson, Jacqueline A.

    2010-01-01

    We present a summary of data obtained with the 350 μm polarimeter, Hertz, at the Caltech Submillimeter Observatory. We give tabulated results and maps showing polarization vectors and intensity contours. The summary includes over 4300 individual measurements in 56 Galactic sources and two galaxies. Of these measurements, 2153 have P ≥ 3σ p statistical significance. The median polarization of the entire data set is 1.46%.

  14. A SUBMILLIMETER CONTINUUM SURVEY OF LOCAL DUST-OBSCURED GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Chul [Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055 (Korea, Republic of); Hwang, Ho Seong [School of Physics, Korea Institute for Advanced Study, 85 Hoegiro, Dongdaemun-gu, Seoul 02455 (Korea, Republic of); Lee, Gwang-Ho, E-mail: jclee@kasi.re.kr [Department of Physics and Astronomy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742 (Korea, Republic of)

    2016-12-20

    We conduct a 350 μ m dust continuum emission survey of 17 dust-obscured galaxies (DOGs) at z = 0.05–0.08 with the Caltech Submillimeter Observatory (CSO). We detect 14 DOGs with S{sub 350μm} = 114–650 mJy and signal-to-noise > 3. By including two additional DOGs with submillimeter data in the literature, we are able to study dust content for a sample of 16 local DOGs, which consist of 12 bump and four power-law types. We determine their physical parameters with a two-component modified blackbody function model. The derived dust temperatures are in the range 57–122 K and 22–35 K for the warm and cold dust components, respectively. The total dust mass and the mass fraction of the warm dust component are 3–34 × 10{sup 7} M {sub ⊙} and 0.03%–2.52%, respectively. We compare these results with those of other submillimeter-detected infrared luminous galaxies. The bump DOGs, the majority of the DOG sample, show similar distributions of dust temperatures and total dust mass to the comparison sample. The power-law DOGs show a hint of smaller dust masses than other samples, but need to be tested with a larger sample. These findings support that the reason DOGs show heavy dust obscuration is not an overall amount of dust content, but probably the spatial distribution of dust therein.

  15. A SUBMILLIMETER CONTINUUM SURVEY OF LOCAL DUST-OBSCURED GALAXIES

    International Nuclear Information System (INIS)

    Lee, Jong Chul; Hwang, Ho Seong; Lee, Gwang-Ho

    2016-01-01

    We conduct a 350 μ m dust continuum emission survey of 17 dust-obscured galaxies (DOGs) at z = 0.05–0.08 with the Caltech Submillimeter Observatory (CSO). We detect 14 DOGs with S 350μm = 114–650 mJy and signal-to-noise > 3. By including two additional DOGs with submillimeter data in the literature, we are able to study dust content for a sample of 16 local DOGs, which consist of 12 bump and four power-law types. We determine their physical parameters with a two-component modified blackbody function model. The derived dust temperatures are in the range 57–122 K and 22–35 K for the warm and cold dust components, respectively. The total dust mass and the mass fraction of the warm dust component are 3–34 × 10 7 M ⊙ and 0.03%–2.52%, respectively. We compare these results with those of other submillimeter-detected infrared luminous galaxies. The bump DOGs, the majority of the DOG sample, show similar distributions of dust temperatures and total dust mass to the comparison sample. The power-law DOGs show a hint of smaller dust masses than other samples, but need to be tested with a larger sample. These findings support that the reason DOGs show heavy dust obscuration is not an overall amount of dust content, but probably the spatial distribution of dust therein.

  16. Problems of noise modeling in the presence of total current branching in high electron mobility transistor and field-effect transistor channels

    International Nuclear Information System (INIS)

    Shiktorov, P; Starikov, E; Gružinskis, V; Varani, L; Sabatini, G; Marinchio, H; Reggiani, L

    2009-01-01

    In the framework of analytical and hydrodynamic models for the description of carrier transport and noise in high electron mobility transistor/field-effect transistor channels the main features of the intrinsic noise of transistors are investigated under continuous branching of the current between channel and gate. It is shown that the current-noise and voltage-noise spectra at the transistor terminals contain an excess noise related to thermal excitation of plasma wave modes in the dielectric layer between the channel and gate. It is found that the set of modes of excited plasma waves can be governed by the external embedding circuits, thus violating a universal description of noise in terms of Norton and Thevenin noise generators

  17. Junctionless Cooper pair transistor

    Energy Technology Data Exchange (ETDEWEB)

    Arutyunov, K. Yu., E-mail: konstantin.yu.arutyunov@jyu.fi [National Research University Higher School of Economics , Moscow Institute of Electronics and Mathematics, 101000 Moscow (Russian Federation); P.L. Kapitza Institute for Physical Problems RAS , Moscow 119334 (Russian Federation); Lehtinen, J.S. [VTT Technical Research Centre of Finland Ltd., Centre for Metrology MIKES, P.O. Box 1000, FI-02044 VTT (Finland)

    2017-02-15

    Highlights: • Junctionless Cooper pair box. • Quantum phase slips. • Coulomb blockade and gate modulation of the Coulomb gap. - Abstract: Quantum phase slip (QPS) is the topological singularity of the complex order parameter of a quasi-one-dimensional superconductor: momentary zeroing of the modulus and simultaneous 'slip' of the phase by ±2π. The QPS event(s) are the dynamic equivalent of tunneling through a conventional Josephson junction containing static in space and time weak link(s). Here we demonstrate the operation of a superconducting single electron transistor (Cooper pair transistor) without any tunnel junctions. Instead a pair of thin superconducting titanium wires in QPS regime was used. The current–voltage characteristics demonstrate the clear Coulomb blockade with magnitude of the Coulomb gap modulated by the gate potential. The Coulomb blockade disappears above the critical temperature, and at low temperatures can be suppressed by strong magnetic field.

  18. Mesoscopic photon heat transistor

    DEFF Research Database (Denmark)

    Ojanen, T.; Jauho, Antti-Pekka

    2008-01-01

    We show that the heat transport between two bodies, mediated by electromagnetic fluctuations, can be controlled with an intermediate quantum circuit-leading to the device concept of a mesoscopic photon heat transistor (MPHT). Our theoretical analysis is based on a novel Meir-Wingreen-Landauer-typ......We show that the heat transport between two bodies, mediated by electromagnetic fluctuations, can be controlled with an intermediate quantum circuit-leading to the device concept of a mesoscopic photon heat transistor (MPHT). Our theoretical analysis is based on a novel Meir......-Wingreen-Landauer-type of conductance formula, which gives the photonic heat current through an arbitrary circuit element coupled to two dissipative reservoirs at finite temperatures. As an illustration we present an exact solution for the case when the intermediate circuit can be described as an electromagnetic resonator. We discuss...

  19. Organic electrochemical transistors

    Science.gov (United States)

    Rivnay, Jonathan; Inal, Sahika; Salleo, Alberto; Owens, Róisín M.; Berggren, Magnus; Malliaras, George G.

    2018-02-01

    Organic electrochemical transistors (OECTs) make effective use of ion injection from an electrolyte to modulate the bulk conductivity of an organic semiconductor channel. The coupling between ionic and electronic charges within the entire volume of the channel endows OECTs with high transconductance compared with that of field-effect transistors, but also limits their response time. The synthetic tunability, facile deposition and biocompatibility of organic materials make OECTs particularly suitable for applications in biological interfacing, printed logic circuitry and neuromorphic devices. In this Review, we discuss the physics and the mechanism of operation of OECTs, focusing on their identifying characteristics. We highlight organic materials that are currently being used in OECTs and survey the history of OECT technology. In addition, form factors, fabrication technologies and applications such as bioelectronics, circuits and memory devices are examined. Finally, we take a critical look at the future of OECT research and development.

  20. Organic electrochemical transistors

    KAUST Repository

    Rivnay, Jonathan

    2018-01-16

    Organic electrochemical transistors (OECTs) make effective use of ion injection from an electrolyte to modulate the bulk conductivity of an organic semiconductor channel. The coupling between ionic and electronic charges within the entire volume of the channel endows OECTs with high transconductance compared with that of field-effect transistors, but also limits their response time. The synthetic tunability, facile deposition and biocompatibility of organic materials make OECTs particularly suitable for applications in biological interfacing, printed logic circuitry and neuromorphic devices. In this Review, we discuss the physics and the mechanism of operation of OECTs, focusing on their identifying characteristics. We highlight organic materials that are currently being used in OECTs and survey the history of OECT technology. In addition, form factors, fabrication technologies and applications such as bioelectronics, circuits and memory devices are examined. Finally, we take a critical look at the future of OECT research and development.

  1. Lightweight Thermally Stable Multi-Meter Aperture Submillimeter Reflectors, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Future astrophysics missions will require lightweight, thermally stable, submillimeter reflectors in sizes of 4m and greater. To date, graphite fiber reinforced...

  2. Transistorized PWM inverter-induction motor drive system

    Science.gov (United States)

    Peak, S. C.; Plunkett, A. B.

    1982-01-01

    This paper describes the development of a transistorized PWM inverter-induction motor traction drive system. A vehicle performance analysis was performed to establish the vehicle tractive effort-speed requirements. These requirements were then converted into a set of inverter and motor specifications. The inverter was a transistorized three-phase bridge using General Electric power Darlington transistors. The description of the design and development of this inverter is the principal object of this paper. The high-speed induction motor is a design which is optimized for use with an inverter power source. The primary feedback control is a torque angle control with voltage and torque outer loop controls. A current-controlled PWM technique is used to control the motor voltage. The drive has a constant torque output with PWM operation to base motor speed and a constant horsepower output with square wave operation to maximum speed. The drive system was dynamometer tested and the results are presented.

  3. Magnon transistor for all-magnon data processing.

    Science.gov (United States)

    Chumak, Andrii V; Serga, Alexander A; Hillebrands, Burkard

    2014-08-21

    An attractive direction in next-generation information processing is the development of systems employing particles or quasiparticles other than electrons--ideally with low dissipation--as information carriers. One such candidate is the magnon: the quasiparticle associated with the eigen-excitations of magnetic materials known as spin waves. The realization of single-chip all-magnon information systems demands the development of circuits in which magnon currents can be manipulated by magnons themselves. Using a magnonic crystal--an artificial magnetic material--to enhance nonlinear magnon-magnon interactions, we have succeeded in the realization of magnon-by-magnon control, and the development of a magnon transistor. We present a proof of concept three-terminal device fabricated from an electrically insulating magnetic material. We demonstrate that the density of magnons flowing from the transistor's source to its drain can be decreased three orders of magnitude by the injection of magnons into the transistor's gate.

  4. Investigation of imaging properties for submillimeter rectangular pinholes

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Dan, E-mail: dxia@uchicago.edu [The Department of Radiology, The University of Chicago, Chicago, Illinois 60637 (United States); Moore, Stephen C., E-mail: scmoore@bwh.harvard.edu, E-mail: miaepark@bwh.harvard.edu, E-mail: mcervo@bwh.harvard.edu; Park, Mi-Ae, E-mail: scmoore@bwh.harvard.edu, E-mail: miaepark@bwh.harvard.edu, E-mail: mcervo@bwh.harvard.edu; Cervo, Morgan, E-mail: scmoore@bwh.harvard.edu, E-mail: miaepark@bwh.harvard.edu, E-mail: mcervo@bwh.harvard.edu [Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts 02115 (United States); Metzler, Scott D., E-mail: metzler@upenn.edu [The Department of Radiology, The University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)

    2015-12-15

    Purpose: Recently, a multipinhole collimator with inserts that have both rectangular apertures and rectangular fields of view (FOVs) has been proposed for SPECT imaging since it can tile the projection onto the detector efficiently and the FOVs in transverse and axial directions become separable. The purpose of this study is to investigate the image properties of rectangular-aperture pinholes with submillimeter apertures sizes. Methods: In this work, the authors have conducted sensitivity and FOV experiments for 18 replicates of a prototype insert fabricated in platinum/iridium (Pt/Ir) alloy with submillimeter square-apertures. A sin{sup q}θ fit to the experimental sensitivity has been performed for these inserts. For the FOV measurement, the authors have proposed a new formula to calculate the projection intensity of a flood image on the detector, taking into account the penumbra effect. By fitting this formula to the measured projection data, the authors obtained the acceptance angles. Results: The mean (standard deviation) of fitted sensitivity exponents q and effective edge lengths w{sub e} were, respectively, 10.8 (1.8) and 0.38 mm (0.02 mm), which were close to the values, 7.84 and 0.396 mm, obtained from Monte Carlo calculations using the parameters of the designed inserts. For the FOV measurement, the mean (standard deviation) of the transverse and axial acceptances were 35.0° (1.2°) and 30.5° (1.6°), which are in good agreement with the designed values (34.3° and 29.9°). Conclusions: These results showed that the physical properties of the fabricated inserts with submillimeter aperture size matched our design well.

  5. CLUMPY AND EXTENDED STARBURSTS IN THE BRIGHTEST UNLENSED SUBMILLIMETER GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Iono, Daisuke; Hatsukade, Bunyo; Kawabe, Ryohei; Matsuda, Yuichi; Nakanishi, Kouichiro [National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Yun, Min S.; Wilson, Grant [University of Massachusetts, Department of Astronomy, 710 North Pleasant Street, Amherst, MA 01003 (United States); Aretxaga, Itziar; Hughes, David [Instituto Nacional de Astrofisica, Optica y Electronica (INAOE), Luis Enrique Erro 1, Sta. Ma. Tonantzintla, Puebla (Mexico); Ikarashi, Soh [Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700AV Groningen (Netherlands); Izumi, Takuma; Kohno, Kotaro; Tamura, Yoichi; Umehata, Hideki [Institute of Astronomy, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Lee, Minju; Saito, Toshiki [Department of Astronomy, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 133-0033 (Japan); Ueda, Junko [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Michiyama, Tomonari; Ando, Misaki, E-mail: d.iono@nao.ac.jp [SOKENDAI (The Graduate University for Advanced Studies), 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

    2016-09-20

    The central structure in three of the brightest unlensed z = 3–4 submillimeter galaxies is investigated through 0.″015–0.″05 (120–360 pc) 860 μ m continuum images obtained using the Atacama Large Millimeter/submillimeter Array (ALMA). The distribution in the central kiloparsec in AzTEC1 and AzTEC8 is extremely complex, and they are composed of multiple ∼200 pc clumps. AzTEC4 consists of two sources that are separated by ∼1.5 kpc, indicating a mid-stage merger. The peak star formation rate densities in the central clumps are ∼300–3000 M {sub ⊙} yr{sup −1} kpc{sup −2}, suggesting regions with extreme star formation near the Eddington limit. By comparing the flux obtained by ALMA and Submillimeter Array, we find that 68%–90% of the emission is extended (≳1 kpc) in AzTEC4 and 8. For AzTEC1, we identify at least 11 additional compact (∼200 pc) clumps in the extended 3–4 kpc region. Overall, the data presented here suggest that the luminosity surface densities observed at ≲150 pc scales are roughly similar to that observed in local ULIRGs, as in the eastern nucleus of Arp 220. Between 10% and 30% of the 860 μ m continuum is concentrated in clumpy structures in the central kiloparsec, while the remaining flux is distributed over ≳1 kpc regions, some of which could also be clumpy. These sources can be explained by a rapid inflow of gas such as a merger of gas-rich galaxies, surrounded by extended and clumpy starbursts. However, the cold mode accretion model is not ruled out.

  6. Surveying Low-Mass Star Formation with the Submillimeter Array

    Science.gov (United States)

    Dunham, Michael

    2018-01-01

    Large astronomical surveys yield important statistical information that can’t be derived from single-object and small-number surveys. In this talk I will review two recent surveys in low-mass star formation undertaken by the Submillimeter Array (SMA): a millimeter continuum survey of disks surrounding variably accreting young stars, and a complete continuum and molecular line survey of all protostars in the nearby Perseus Molecular Cloud. I will highlight several new insights into the processes by which low-mass stars gain their mass that have resulted from the statistical power of these surveys.

  7. Dosimetric properties of MOS transistors

    International Nuclear Information System (INIS)

    Peter, I.; Frank, G.

    1977-01-01

    The performance of MOS transistors as gamma detectors has been tested. The dosimeter sensitivity has proved to be independent on the doses ranging from 10 3 to 10 6 R, and gamma energy of 137 Cs, 60 Co - sources and 5 - 18 MeV electrons. Fading of the space charge trapped by the SiO 2 layer of the transistor has appeared to be neglegible at room temperature after 400 hrs. The isochronous annealing in the temperature range of 40-260 deg C had a more substantial effect on the space charge of the transistor irradiated with 18 MeV electrons than on the 137 Cs gamma-irradiated transistors. This proved a repeated use of γ-dosemeters. MOS transistors are concluded to be promising for gamma dosimetry [ru

  8. Spin Hall effect transistor

    Czech Academy of Sciences Publication Activity Database

    Wunderlich, Joerg; Park, B.G.; Irvine, A.C.; Zarbo, Liviu; Rozkotová, E.; Němec, P.; Novák, Vít; Sinova, Jairo; Jungwirth, Tomáš

    2010-01-01

    Roč. 330, č. 6012 (2010), s. 1801-1804 ISSN 0036-8075 R&D Projects: GA AV ČR KAN400100652; GA MŠk LC510 EU Projects: European Commission(XE) 215368 - SemiSpinNet Grant - others:AV ČR(CZ) AP0801 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100521 Keywords : spin Hall effect * spintronics * spin transistor Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 31.364, year: 2010

  9. Transition-Edge Hot-Electron Microbolometers for Millimeter and Submillimeter Astrophysics

    Science.gov (United States)

    Hsieh, Wen-Ting; Stevenson, Thomas; U-yen, Kongpop; Wollack, Edward; Barrentine, Emily

    2014-01-01

    The millimeter and the submillimeter wavelengths of the electromagnetic spectrum hold a wealth of information about the evolution of the universe. In particular, cosmic microwave background (CMB) radiation and its polarization carry the oldest information in the universe, and provide the best test of the inflationary paradigm available to astronomy today. Detecting gravity waves through their imprint on the CMB polarization would have extraordinary repercussions for cosmology and physics. A transition-edge hot-electron micro - bolometer (THM) consists of a superconducting bilayer transition-edge sensor (TES) with a thin-film absorber. Unlike traditional monolithic bolometers that make use of micromachined structures, the THM em ploys the decoupling between electrons and phonons at millikelvin temperatures to provide thermal isolation. The devices are fabricated photolithographically and are easily integrated with antennas via microstrip transmission lines, and with SQUID (superconducting quantum interference device) readouts. The small volume of the absorber and TES produces a short thermal time constant that facilitates rapid sky scanning. The THM consists of a thin-film metal absorber overlapping a superconducting TES. The absorber forms the termination of a superconducting microstripline that carries RF power from an antenna. The purpose of forming a separate absorber and TES is to allow flexibility in the optimization of the two components. In particular, the absorbing film's impedance can be chosen to match the antenna, while the TES impedance can be chosen to match to the readout SQUID amplifier. This scheme combines the advantages of the TES with the advantages of planar millimeter-wave transmission line circuits. Antenna-coupling to the detectors via planar transmission lines allows the detector dimensions to be much smaller than a wavelength, so the technique can be extended across the entire microwave, millimeter, and submillimeter wavelength ranges. The

  10. Josephson frequency meter for millimeter and submillimeter wavelengths

    International Nuclear Information System (INIS)

    Anischenko, S.E.; Larkin, S.Y.; Chaikovsky, V.I.

    1994-01-01

    Frequency measurements of electromagnetic oscillations of millimeter and submillimeter wavebands with frequency growth due to a number of reasons become more and more difficult. First, these frequencies are considered to be cutoff for semiconductor converting devices and one has to use optical measurement methods instead of traditional ones with frequency transfer. Second, resonance measurement methods are characterized by using relatively narrow bands and optical ones are limited in frequency and time resolution due to the limited range and velocity of movement of their mechanical elements as well as the efficiency of these optical techniques decreases with the increase of wavelength due to diffraction losses. That requires the apriori information on the radiation frequency band of the source involved. Method of measuring frequency of harmonic microwave signals in millimeter and submillimeter wavebands based on the ac Josephson effect in superconducting contacts is devoid of all the above drawbacks. This approach offers a number of major advantages over the more traditional measurement methods, that is the one based on frequency conversion, resonance and interferrometric techniques. It can be characterized by high potential accuracy, wide range of frequencies measured, prompt measurement and the opportunity to obtain panoramic display of the results as well as full automation of the measuring process

  11. Josephson frequency meter for millimeter and submillimeter wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Anischenko, S.E.; Larkin, S.Y.; Chaikovsky, V.I. [State Research Center, Kiev (Ukraine)] [and others

    1994-12-31

    Frequency measurements of electromagnetic oscillations of millimeter and submillimeter wavebands with frequency growth due to a number of reasons become more and more difficult. First, these frequencies are considered to be cutoff for semiconductor converting devices and one has to use optical measurement methods instead of traditional ones with frequency transfer. Second, resonance measurement methods are characterized by using relatively narrow bands and optical ones are limited in frequency and time resolution due to the limited range and velocity of movement of their mechanical elements as well as the efficiency of these optical techniques decreases with the increase of wavelength due to diffraction losses. That requires the apriori information on the radiation frequency band of the source involved. Method of measuring frequency of harmonic microwave signals in millimeter and submillimeter wavebands based on the ac Josephson effect in superconducting contacts is devoid of all the above drawbacks. This approach offers a number of major advantages over the more traditional measurement methods, that is the one based on frequency conversion, resonance and interferrometric techniques. It can be characterized by high potential accuracy, wide range of frequencies measured, prompt measurement and the opportunity to obtain panoramic display of the results as well as full automation of the measuring process.

  12. Development of a Submillimeter-Wavelength Immersion Grating Spectrometer

    Science.gov (United States)

    Phillips, T. G.

    2001-01-01

    The broad goal of this project was to develop a broadband, moderate-resolution spectrometer for submillimeter wavelengths. Our original approach was to build an immersion grating spectrometer, and as such, the first step was to identify the best material (lowest loss, highest index) for the grating medium, and to characterize its properties at the foreseen optical-bench operating temperature of 1.5 K. To this end, we put our initial efforts into upgrading an existing laboratory submillimeter Fourier transform spectrometer, which allowed us to carry out the requisite materials measurements. The associated cryogenic detector dewar was also redesigned and rebuilt to carry out this work. This dewar houses the 1.5 K detector and the filter wheel used in the materials characterization. Our goal was to have the beam propagate through the samples as uniformly as possible, so the optics were redesigned to allow for the samples to be traversed by a well-defined collimated beam. The optics redesign also placed the samples at an image of the aperture stop located within the FTS. After the rebuild, we moved into the testing phase.

  13. Focal plane optics in far-infrared and submillimeter astronomy

    Science.gov (United States)

    Hildebrand, R. H.

    1985-01-01

    The construction of airborne observatories, high mountain-top observatories, and space observatories designed especially for infrared and submillimeter astronomy has opened fields of research requiring new optical techniques. A typical far-IR photometric study involves measurement of a continuum spectrum in several passbands between approx 30 microns and 1000 microns and diffraction-limited mapping of the source. At these wavelengths, diffraction effects strongly influence the design of the field optics systems which couple the incoming flux to the radiation sensors (cold bolometers). The Airy diffraction disk for a typical telescope at submillimeter wavelengths approx 100 microns-1000 microns is many millimeters in diameter; the size of the field stop must be comparable. The dilute radiation at the stop is fed through a Winston nonimaging concentrator to a small cavity containing the bolometer. The purpose of this paper is to review the principles and techniques of infrared field optics systems, including spectral filters, concentrators, cavities, and bolometers (as optical elements), with emphasis on photometric systems for wavelengths longer than 60 microns.

  14. Focal plane optics in far-infrared and submillimeter astronomy

    Science.gov (United States)

    Hildebrand, R. H.

    1986-02-01

    The construction of airborne observatories, high mountain-top observatories, and space observatories designed especially for infrared and submillimeter astronomy has opened fields of research requiring new optical techniques. A typical far-IR photometric study involves measurement of a continuum spectrum in several passbands between approx 30 microns and 1000 microns and diffraction-limited mapping of the source. At these wavelengths, diffraction effects strongly influence the design of the field optics systems which couple the incoming flux to the radiation sensors (cold bolometers). The Airy diffraction disk for a typical telescope at submillimeter wavelengths approx 100 microns-1000 microns is many millimeters in diameter; the size of the field stop must be comparable. The dilute radiation at the stop is fed through a Winston nonimaging concentrator to a small cavity containing the bolometer. The purpose of this paper is to review the principles and techniques of infrared field optics systems, including spectral filters, concentrators, cavities, and bolometers (as optical elements), with emphasis on photometric systems for wavelengths longer than 60 microns.

  15. Physical limits of silicon transistors and circuits

    International Nuclear Information System (INIS)

    Keyes, Robert W

    2005-01-01

    A discussion on transistors and electronic computing including some history introduces semiconductor devices and the motivation for miniaturization of transistors. The changing physics of field-effect transistors and ways to mitigate the deterioration in performance caused by the changes follows. The limits of transistors are tied to the requirements of the chips that carry them and the difficulties of fabricating very small structures. Some concluding remarks about transistors and limits are presented

  16. Copper atomic-scale transistors.

    Science.gov (United States)

    Xie, Fangqing; Kavalenka, Maryna N; Röger, Moritz; Albrecht, Daniel; Hölscher, Hendrik; Leuthold, Jürgen; Schimmel, Thomas

    2017-01-01

    We investigated copper as a working material for metallic atomic-scale transistors and confirmed that copper atomic-scale transistors can be fabricated and operated electrochemically in a copper electrolyte (CuSO 4 + H 2 SO 4 ) in bi-distilled water under ambient conditions with three microelectrodes (source, drain and gate). The electrochemical switching-on potential of the atomic-scale transistor is below 350 mV, and the switching-off potential is between 0 and -170 mV. The switching-on current is above 1 μA, which is compatible with semiconductor transistor devices. Both sign and amplitude of the voltage applied across the source and drain electrodes ( U bias ) influence the switching rate of the transistor and the copper deposition on the electrodes, and correspondingly shift the electrochemical operation potential. The copper atomic-scale transistors can be switched using a function generator without a computer-controlled feedback switching mechanism. The copper atomic-scale transistors, with only one or two atoms at the narrowest constriction, were realized to switch between 0 and 1 G 0 ( G 0 = 2e 2 /h; with e being the electron charge, and h being Planck's constant) or 2 G 0 by the function generator. The switching rate can reach up to 10 Hz. The copper atomic-scale transistor demonstrates volatile/non-volatile dual functionalities. Such an optimal merging of the logic with memory may open a perspective for processor-in-memory and logic-in-memory architectures, using copper as an alternative working material besides silver for fully metallic atomic-scale transistors.

  17. Programmable automated transistor test system

    International Nuclear Information System (INIS)

    Truong, L.V.; Sundberg, G.R.

    1986-01-01

    The paper describes a programmable automated transistor test system (PATTS) and its utilization to evaluate bipolar transistors and Darlingtons, and such MOSFET and special types as can be accommodated with the PATTS base-drive. An application of a pulsed power technique at low duty cycles in a non-destructive test is used to examine the dynamic switching characteristic curves of power transistors. Data collection, manipulation, storage, and output are operator interactive but are guided and controlled by the system software. In addition a library of test data is established on disks, tapes, and hard copies for future reference

  18. Prospects for ion temperature measurements in JET by Thomson scattering of submillimetre waves

    International Nuclear Information System (INIS)

    Whitbourn, L.B.

    1975-03-01

    The Thomson scattering of submillimeter waves is envisaged as a possible means for measuring the ion temperature of the JET plasma. The present discussion is principally concerned with the practical limitations imposed to the method by the availability of high power pulsed sources and sensitive detectors and noise due to plasma emission at submillimeter wavelengths (bremsstrahlung and electron cyclotron emission). Coherent scattering from plasma wave (e.g. ion acoustic waves and electron drift waves) with millimeter and submillimeter waves are considered briefly. Further suitable development of lasers and heterodyne detectors would make such measurements possible. A pulsed HCN laser associated with a detectors with a lower heterodyne noise equivalent power could then be used to advantage. For scattering with CH 3 F laser the NEP of a Josephson junction would be adequate because a relatively high level of plasma emission is expected at 496 μm [fr

  19. Model-based cartilage thickness measurement in the submillimeter range

    International Nuclear Information System (INIS)

    Streekstra, G. J.; Strackee, S. D.; Maas, M.; Wee, R. ter; Venema, H. W.

    2007-01-01

    Current methods of image-based thickness measurement in thin sheet structures utilize second derivative zero crossings to locate the layer boundaries. It is generally acknowledged that the nonzero width of the point spread function (PSF) limits the accuracy of this measurement procedure. We propose a model-based method that strongly reduces PSF-induced bias by incorporating the PSF into the thickness estimation method. We estimated the bias in thickness measurements in simulated thin sheet images as obtained from second derivative zero crossings. To gain insight into the range of sheet thickness where our method is expected to yield improved results, sheet thickness was varied between 0.15 and 1.2 mm with an assumed PSF as present in the high-resolution modes of current computed tomography (CT) scanners [full width at half maximum (FWHM) 0.5-0.8 mm]. Our model-based method was evaluated in practice by measuring layer thickness from CT images of a phantom mimicking two parallel cartilage layers in an arthrography procedure. CT arthrography images of cadaver wrists were also evaluated, and thickness estimates were compared to those obtained from high-resolution anatomical sections that served as a reference. The thickness estimates from the simulated images reveal that the method based on second derivative zero crossings shows considerable bias for layers in the submillimeter range. This bias is negligible for sheet thickness larger than 1 mm, where the size of the sheet is more than twice the FWHM of the PSF but can be as large as 0.2 mm for a 0.5 mm sheet. The results of the phantom experiments show that the bias is effectively reduced by our method. The deviations from the true thickness, due to random fluctuations induced by quantum noise in the CT images, are of the order of 3% for a standard wrist imaging protocol. In the wrist the submillimeter thickness estimates from the CT arthrography images correspond within 10% to those estimated from the anatomical

  20. The Submillimeter Spectrum of MnH and MnD (X7Σ+)

    Science.gov (United States)

    Halfen, D. T.; Ziurys, L. M.

    2008-01-01

    The submillimeter-wave spectrum of the MnH and MnD radicals in their 7Σ+ ground states has been measured in the laboratory using direct absorption techniques. These species were created in the gas phase by the reaction of manganese vapor, produced in a Broida-type oven, with either H2 or D2 gas in the presence of a DC discharge. The N = 0 → 1 transition of MnH near 339 GHz was recorded, which consisted of multiple hyperfine components arising from both the manganese and hydrogen nuclear spins. The N = 2 → 3 transition of MnD near 517 GHz was measured as well, but in this case only the manganese hyperfine interactions were resolved. Both data sets were analyzed with a Hund's case b Hamiltonian, and rotational, fine structure, magnetic hyperfine, and electric quadrupole constants have been determined for the two manganese species. An examination of the magnetic hyperfine constants shows that MnH is primarily an ionic species, but has more covalent character than MnF. MnH is a good candidate species for astronomical searches with Herschel, particularly toward material associated with luminous blue variable stars.

  1. High-Sensitivity AGN Polarimetry at Sub-Millimeter Wavelengths

    Directory of Open Access Journals (Sweden)

    Ivan Martí-Vidal

    2017-10-01

    Full Text Available The innermost regions of radio loud Active Galactic Nuclei (AGN jets are heavily affected by synchrotron self-absorption, due to the strong magnetic fields and high particle densities in these extreme zones. The only way to overcome this absorption is to observe at sub-millimeter wavelengths, although polarimetric observations at such frequencies have so far been limited by sensitivity and calibration accuracy. However, new generation instruments such as the Atacama Large mm/sub-mm Array (ALMA overcome these limitations and are starting to deliver revolutionary results in the observational studies of AGN polarimetry. Here we present an overview of our state-of-the-art interferometric mm/sub-mm polarization observations of AGN jets with ALMA (in particular, the gravitationally-lensed sources PKS 1830−211 and B0218+359, which allow us to probe the magneto-ionic conditions at the regions closest to the central black holes.

  2. SUBMILLIMETER POLARIZATION SPECTRUM IN THE VELA C MOLECULAR CLOUD

    Energy Technology Data Exchange (ETDEWEB)

    Gandilo, Natalie N. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street Toronto, ON M5S 3H4 (Canada); Ade, Peter A. R.; Pascale, Enzo [Cardiff University, School of Physics and Astronomy, Queens Buildings, The Parade, Cardiff, CF24 3AA (United Kingdom); Angilè, Francesco E.; Devlin, Mark J.; Dober, Bradley; Galitzki, Nicholas; Klein, Jeffrey [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA, 19104 (United States); Ashton, Peter; Fissel, Laura M.; Matthews, Tristan G.; Novak, Giles [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Benton, Steven J. [Department of Physics, Princeton University, Jadwin Hall, Princeton, NJ 08544 (United States); Fukui, Yasuo [Department of Physics and Astrophysics, Nagoya University, Nagoya 464-8602 (Japan); Korotkov, Andrei L. [Department of Physics, Brown University, 182 Hope Street, Providence, RI, 02912 (United States); Li, Zhi-Yun [Department of Astronomy, University of Virginia, 530 McCormick Road, Charlottesville, VA 22904 (United States); Martin, Peter G. [CITA, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8 (Canada); Moncelsi, Lorenzo [California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA, 91125 (United States); Nakamura, Fumitaka [National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan); Netterfield, Calvin B., E-mail: ngandil1@jhu.edu [Department of Physics and Astronomy, Johns Hopkins University, 3701 San Martin Drive, Baltimore, Maryland (United States); and others

    2016-06-20

    Polarization maps of the Vela C molecular cloud were obtained at 250, 350, and 500 μ m during the 2012 flight of the balloon-borne telescope BLASTPol. These measurements are used in conjunction with 850 μ m data from Planck to study the submillimeter spectrum of the polarization fraction for this cloud. The spectrum is relatively flat and does not exhibit a pronounced minimum at λ ∼ 350 μ m as suggested by previous measurements of other molecular clouds. The shape of the spectrum does not depend strongly on the radiative environment of the dust, as quantified by the column density or the dust temperature obtained from Herschel data. The polarization ratios observed in Vela C are consistent with a model of a porous clumpy molecular cloud being uniformly heated by the interstellar radiation field.

  3. Submillimeter and millimeter observations of solar system objects

    International Nuclear Information System (INIS)

    Muhleman, D.O.

    1988-01-01

    Planetary atmospheres and satellite surfaces are observed with the three element array at Caltech's Owens Valley Radio Observatory, Caltech's submillimeter telescope on Mauna Kea and at the 12-meter telescope at Kitt Peak. Researchers are primarily interested in spectroscopy of the atmospheres of Venus, Mars and Titan and the continuum structure of Saturn Rings, Galilean satellites, Neptune and Uranus. During the last year researchers completed a supersynthesis of the Saturn system at 2.8 mm with spatial resolution of 3 arc sec. They just completed a 4-confuguration synthesis of Venus in the CO absorption line. They hope to recover the wind patterns in the altitude range from 60 to 100 km where winds have never been measured. Two important questions are being investigated: (1) how high in the Venus atmosphere do 4-day winds extend, and (2) can we produce experiment proof (or disproof) of the subsolar-to-anti-solar flow (Dickenson winds) predicted by general circulation models

  4. Transistor and integrated circuit manufacture

    International Nuclear Information System (INIS)

    Colman, D.

    1978-01-01

    This invention relates to the manufacture of transistors and integrated circuits by ion bombardment techniques and is particularly, but not exclusively, of value in the manufacture of so-called integrated injection logic circuitry. (author)

  5. High transconductance organic electrochemical transistors

    Science.gov (United States)

    Khodagholy, Dion; Rivnay, Jonathan; Sessolo, Michele; Gurfinkel, Moshe; Leleux, Pierre; Jimison, Leslie H.; Stavrinidou, Eleni; Herve, Thierry; Sanaur, Sébastien; Owens, Róisín M.; Malliaras, George G.

    2013-07-01

    The development of transistors with high gain is essential for applications ranging from switching elements and drivers to transducers for chemical and biological sensing. Organic transistors have become well-established based on their distinct advantages, including ease of fabrication, synthetic freedom for chemical functionalization, and the ability to take on unique form factors. These devices, however, are largely viewed as belonging to the low-end of the performance spectrum. Here we present organic electrochemical transistors with a transconductance in the mS range, outperforming transistors from both traditional and emerging semiconductors. The transconductance of these devices remains fairly constant from DC up to a frequency of the order of 1 kHz, a value determined by the process of ion transport between the electrolyte and the channel. These devices, which continue to work even after being crumpled, are predicted to be highly relevant as transducers in biosensing applications.

  6. Organic tunnel field effect transistors

    KAUST Repository

    Tietze, Max Lutz; Lussem, Bjorn; Liu, Shiyi

    2017-01-01

    Various examples are provided for organic tunnel field effect transistors (OTFET), and methods thereof. In one example, an OTFET includes a first intrinsic layer (i-layer) of organic semiconductor material disposed over a gate insulating layer

  7. High transconductance organic electrochemical transistors

    Science.gov (United States)

    Khodagholy, Dion; Rivnay, Jonathan; Sessolo, Michele; Gurfinkel, Moshe; Leleux, Pierre; Jimison, Leslie H.; Stavrinidou, Eleni; Herve, Thierry; Sanaur, Sébastien; Owens, Róisín M.; Malliaras, George G.

    2013-01-01

    The development of transistors with high gain is essential for applications ranging from switching elements and drivers to transducers for chemical and biological sensing. Organic transistors have become well-established based on their distinct advantages, including ease of fabrication, synthetic freedom for chemical functionalization, and the ability to take on unique form factors. These devices, however, are largely viewed as belonging to the low-end of the performance spectrum. Here we present organic electrochemical transistors with a transconductance in the mS range, outperforming transistors from both traditional and emerging semiconductors. The transconductance of these devices remains fairly constant from DC up to a frequency of the order of 1 kHz, a value determined by the process of ion transport between the electrolyte and the channel. These devices, which continue to work even after being crumpled, are predicted to be highly relevant as transducers in biosensing applications. PMID:23851620

  8. Transistor and integrated circuit manufacture

    Energy Technology Data Exchange (ETDEWEB)

    Colman, D

    1978-09-27

    This invention relates to the manufacture of transistors and integrated circuits by ion bombardment techniques and is particularly, but not exclusively, of value in the manufacture of so-called integrated injection logic circuitry.

  9. SUBMILLIMETER FOLLOW-UP OF WISE-SELECTED HYPERLUMINOUS GALAXIES

    International Nuclear Information System (INIS)

    Wu Jingwen; Eisenhardt, Peter R. M.; Stern, Daniel; Assef, Roberto; Tsai, Chao-Wei; Cutri, Roc; Griffith, Roger; Jarrett, Thomas; Sayers, Jack; Bridge, Carrie; Benford, Dominic; Blain, Andrew; Petty, Sara; Lake, Sean; Bussmann, Shane; Comerford, Julia M.; Evans, Neal J. II; Lonsdale, Carol; Rho, Jeonghee; Stanford, S. Adam

    2012-01-01

    We have used the Caltech Submillimeter Observatory (CSO) to follow-up a sample of Wide-field Infrared Survey Explorer (WISE) selected, hyperluminous galaxies, the so-called W1W2-dropout galaxies. This is a rare (∼1000 all-sky) population of galaxies at high redshift (peaks at z = 2-3), which are faint or undetected by WISE at 3.4 and 4.6 μm, yet are clearly detected at 12 and 22 μm. The optical spectra of most of these galaxies show significant active galactic nucleus activity. We observed 14 high-redshift (z > 1.7) W1W2-dropout galaxies with SHARC-II at 350-850 μm, with nine detections, and observed 18 with Bolocam at 1.1 mm, with five detections. Warm Spitzer follow-up of 25 targets at 3.6 and 4.5 μm, as well as optical spectra of 12 targets, are also presented in the paper. Combining WISE data with observations from warm Spitzer and CSO, we constructed their mid-IR to millimeter spectral energy distributions (SEDs). These SEDs have a consistent shape, showing significantly higher mid-IR to submillimeter ratios than other galaxy templates, suggesting a hotter dust temperature. We estimate their dust temperatures to be 60-120 K using a single-temperature model. Their infrared luminosities are well over 10 13 L ☉ . These SEDs are not well fitted with existing galaxy templates, suggesting they are a new population with very high luminosity and hot dust. They are likely among the most luminous galaxies in the universe. We argue that they are extreme cases of luminous, hot dust-obscured galaxies (DOGs), possibly representing a short evolutionary phase during galaxy merging and evolution. A better understanding of their long-wavelength properties needs ALMA as well as Herschel data.

  10. Submillimeter Follow-up of Wise-Selected Hyperluminous Galaxies

    Science.gov (United States)

    Wu, Jingwen; Tsai, Chao-Wei; Sayers, Jack; Benford, Dominic; Bridge, Carrie; Blain, Andrew; Eisenhardt, Peter R. M.; Stern, Daniel; Petty, Sara; Assef, Roberto; hide

    2013-01-01

    We have used the Caltech Submillimeter Observatory (CSO) to follow-up a sample of Wide-field Infrared Survey Explorer (WISE) selected, hyperluminous galaxies, the so-called W1W2-dropout galaxies. This is a rare (approximately 1000 all-sky) population of galaxies at high redshift (peaks at zeta = 2-3), which are faint or undetected by WISE at 3.4 and 4.6 micrometers, yet are clearly detected at 12 and 22 micrometers. The optical spectra of most of these galaxies show significant active galactic nucleus activity. We observed 14 high-redshift (zeta greater than 1.7) W1W2-dropout galaxies with SHARC-II at 350-850 micrometers, with nine detections, and observed 18 with Bolocam at 1.1 mm, with five detections. Warm Spitzer follow-up of 25 targets at 3.6 and 4.5 micrometers, as well as optical spectra of 12 targets, are also presented in the paper. Combining WISE data with observations from warm Spitzer and CSO, we constructed their mid-IR to millimeter spectral energy distributions (SEDs). These SEDs have a consistent shape, showing significantly higher mid-IR to submillimeter ratios than other galaxy templates, suggesting a hotter dust temperature.We estimate their dust temperatures to be 60-120 K using a single-temperature model. Their infrared luminosities are well over 10(exp 13) solar luminosity. These SEDs are not well fitted with existing galaxy templates, suggesting they are a new population with very high luminosity and hot dust. They are likely among the most luminous galaxies in the universe.We argue that they are extreme cases of luminous, hot dust-obscured galaxies (DOGs), possibly representing a short evolutionary phase during galaxy merging and evolution. A better understanding of their long-wavelength properties needs ALMA as well as Herschel data.

  11. SUBMILLIMETER FOLLOW-UP OF WISE-SELECTED HYPERLUMINOUS GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Wu Jingwen; Eisenhardt, Peter R. M.; Stern, Daniel; Assef, Roberto [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Tsai, Chao-Wei; Cutri, Roc; Griffith, Roger; Jarrett, Thomas [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Sayers, Jack; Bridge, Carrie [Division of Physics, Math and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Benford, Dominic [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Blain, Andrew [Department of Physics and Astronomy, University of Leicester, LE1 7RH Leicester (United Kingdom); Petty, Sara; Lake, Sean [Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, CA 90095 (United States); Bussmann, Shane [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS78, Cambridge, MA 02138 (United States); Comerford, Julia M.; Evans, Neal J. II [Department of Astronomy, University of Texas, Austin, TX 78731 (United States); Lonsdale, Carol [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Rho, Jeonghee [SETI Institute, 189 BERNARDO Avenue, Mountain View, CA 94043 (United States); Stanford, S. Adam, E-mail: jingwen.wu@jpl.nasa.gov [Department of Physics, University of California Davis, One Shields Avenue, Davis, CA 95616 (United States); and others

    2012-09-01

    We have used the Caltech Submillimeter Observatory (CSO) to follow-up a sample of Wide-field Infrared Survey Explorer (WISE) selected, hyperluminous galaxies, the so-called W1W2-dropout galaxies. This is a rare ({approx}1000 all-sky) population of galaxies at high redshift (peaks at z = 2-3), which are faint or undetected by WISE at 3.4 and 4.6 {mu}m, yet are clearly detected at 12 and 22 {mu}m. The optical spectra of most of these galaxies show significant active galactic nucleus activity. We observed 14 high-redshift (z > 1.7) W1W2-dropout galaxies with SHARC-II at 350-850 {mu}m, with nine detections, and observed 18 with Bolocam at 1.1 mm, with five detections. Warm Spitzer follow-up of 25 targets at 3.6 and 4.5 {mu}m, as well as optical spectra of 12 targets, are also presented in the paper. Combining WISE data with observations from warm Spitzer and CSO, we constructed their mid-IR to millimeter spectral energy distributions (SEDs). These SEDs have a consistent shape, showing significantly higher mid-IR to submillimeter ratios than other galaxy templates, suggesting a hotter dust temperature. We estimate their dust temperatures to be 60-120 K using a single-temperature model. Their infrared luminosities are well over 10{sup 13} L{sub Sun }. These SEDs are not well fitted with existing galaxy templates, suggesting they are a new population with very high luminosity and hot dust. They are likely among the most luminous galaxies in the universe. We argue that they are extreme cases of luminous, hot dust-obscured galaxies (DOGs), possibly representing a short evolutionary phase during galaxy merging and evolution. A better understanding of their long-wavelength properties needs ALMA as well as Herschel data.

  12. Status of MUSIC, the MUltiwavelength Sub/millimeter Inductance Camera

    Science.gov (United States)

    Golwala, Sunil R.; Bockstiegel, Clint; Brugger, Spencer; Czakon, Nicole G.; Day, Peter K.; Downes, Thomas P.; Duan, Ran; Gao, Jiansong; Gill, Amandeep K.; Glenn, Jason; Hollister, Matthew I.; LeDuc, Henry G.; Maloney, Philip R.; Mazin, Benjamin A.; McHugh, Sean G.; Miller, David; Noroozian, Omid; Nguyen, Hien T.; Sayers, Jack; Schlaerth, James A.; Siegel, Seth; Vayonakis, Anastasios K.; Wilson, Philip R.; Zmuidzinas, Jonas

    2012-09-01

    We present the status of MUSIC, the MUltiwavelength Sub/millimeter Inductance Camera, a new instrument for the Caltech Submillimeter Observatory. MUSIC is designed to have a 14', diffraction-limited field-of-view instrumented with 2304 detectors in 576 spatial pixels and four spectral bands at 0.87, 1.04, 1.33, and 1.98 mm. MUSIC will be used to study dusty star-forming galaxies, galaxy clusters via the Sunyaev-Zeldovich effect, and star formation in our own and nearby galaxies. MUSIC uses broadband superconducting phased-array slot-dipole antennas to form beams, lumpedelement on-chip bandpass filters to define spectral bands, and microwave kinetic inductance detectors to sense incoming light. The focal plane is fabricated in 8 tiles consisting of 72 spatial pixels each. It is coupled to the telescope via an ambient-temperature ellipsoidal mirror and a cold reimaging lens. A cold Lyot stop sits at the image of the primary mirror formed by the ellipsoidal mirror. Dielectric and metal-mesh filters are used to block thermal infrared and out-ofband radiation. The instrument uses a pulse tube cooler and 3He/ 3He/4He closed-cycle cooler to cool the focal plane to below 250 mK. A multilayer shield attenuates Earth's magnetic field. Each focal plane tile is read out by a single pair of coaxes and a HEMT amplifier. The readout system consists of 16 copies of custom-designed ADC/DAC and IF boards coupled to the CASPER ROACH platform. We focus on recent updates on the instrument design and results from the commissioning of the full camera in 2012.

  13. Far-infrared and submillimeter spectroscopy of photodissociation regions

    International Nuclear Information System (INIS)

    Qaiyum, A.

    1993-12-01

    The physical properties of the galactic and extragalactic photodissociation regions, warm gas components molecular clouds are, generally, derived through the far-infrared (FIR) fine structure and submillimeter line emissions arising out of these regions. In the theoretical studies of these lines the model of Tielens and Hollenbach (herein after referred as TH) are usually employed in which all the opacity is assumed local in escape probability formalism and inward directed photons do not escape. These assumptions are contrary to the observational facts, where most of the lines are found optically thin except OI (63 μm) and low rotational transitions of CO and some other molecules. The optically thin medium will allow the radiation to escape through any face of the region. These observational evidences let us to assume finite parallel plane slab, instead of semi-infinite parallel slab, in which the photons are allowed to escape from both surfaces (back and front). In the present study an attempt has been made to incorporate the two sided escape of photons from the PDRs and to study its effect on the FIR and submillimeter line emission from the PDRs/molecular clouds. Further the present formalism is also employed to study the clumpy PDRs/molecular clouds. The preliminary results show that now serious consequences are found on the thermal and chemical structure of the regions but individual line emissions are modified by differing factors. Particularly at low density and low kinetic temperature the change is substantial but at density greater than the critical density of the line and temperature close to the excitation temperature its effect is almost negligible. An attempt has also been made to study the physical conditions of the M17 region employing the present formalism. (author). 49 refs, 8 figs, 1 tab

  14. Dosimetric properties of MOS transistors

    International Nuclear Information System (INIS)

    Frank, H.; Petr, I.

    1977-01-01

    The structure of MOS transistors is described and their characteristics given. The experiments performed and data in the literature show the following dosimetric properties of MOS transistors: while for low gamma doses the transistor response to exposure is linear, it shows saturation for higher doses (exceeding 10 3 Gy in tissue). The response is independent of the energy of radiation and of the dose rate (within 10 -2 to 10 5 Gy/s). The spontaneous reduction with time of the spatial charge captured by the oxide layer (fading) is small and acceptable from the point of view of dosimetry. Curves are given of isochronous annealing of the transistors following irradiation with 137 Cs and 18 MeV electrons for different voltages during irradiation. The curves show that in MOS transistors irradiated with high-energy electrons the effect of annealing is less than in transistors irradiated with 137 Cs. In view of the requirement of using higher temperatures (approx. 400 degC) for the complete ''erasing'' of the captured charge, unsealed systems must be used for dosimetric purposes. The effect was also studied of neutron radiation, proton radiation and electron radiation on the MOS transistor structure. For MOS transistor irradiation with 14 MeV neutrons from a neutron generator the response was 4% of that for gamma radiation at the same dose equivalent. The effect of proton radiation was studied as related to the changes in MOS transistor structure during space flights. The response curve shapes are similar to those of gamma radiation curves. The effect of electron radiation on the MOS structure was studied by many authors. The experiments show that for each thickness of the SiO 2 layer an electron energy exists at which the size of the charge captured in SiO 2 is the greatest. All data show that MOS transistors are promising for radiation dosimetry. The main advantage of MOS transistors as gamma dosemeters is the ease and speed of evaluation, low sensitivity to neutron

  15. Planar-Processed Polymer Transistors.

    Science.gov (United States)

    Xu, Yong; Sun, Huabin; Shin, Eul-Yong; Lin, Yen-Fu; Li, Wenwu; Noh, Yong-Young

    2016-10-01

    Planar-processed polymer transistors are proposed where the effective charge injection and the split unipolar charge transport are all on the top surface of the polymer film, showing ideal device characteristics with unparalleled performance. This technique provides a great solution to the problem of fabrication limitations, the ambiguous operating principle, and the performance improvements in practical applications of conjugated-polymer transistors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Multi-imaging adaptive concept for IR and submillimeter space telescopes

    Science.gov (United States)

    Vasilyev, Victor P.

    1995-06-01

    Nontraditional IR and submillimeter spaceborne telescope concept basing on blind-type parabolic multi-ring mirror is proposed and discussed. Preliminary results for optimization of mirror parameters by means of computer simulation are presented.

  17. Lightweight Thermally Stable Multi-Meter Aperture Submillimeter Reflectors, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of the Phase II effort will be an affordable demonstrated full-scale design for a thermally stable multi-meter submillimeter reflector. The Phase I...

  18. Status of the USA program on the development of submillimeter lasers to measure ion temperatures

    International Nuclear Information System (INIS)

    Barnett, C.F.; Hutchinson, D.P.; Vander Sluis, K.; Staats, P.A.

    1977-01-01

    The concept of ion laser scattering is outlined briefly and the parameters of the required submillimeter laser system are described. The current state of the development of lasers, laser and viewing dumps, and detectors is reviewed

  19. Superconducting Microwave Resonator Arrays for Submillimeter/Far-Infrared Imaging

    Science.gov (United States)

    Noroozian, Omid

    Superconducting microwave resonators have the potential to revolutionize submillimeter and far-infrared astronomy, and with it our understanding of the universe. The field of low-temperature detector technology has reached a point where extremely sensitive devices like transition-edge sensors are now capable of detecting radiation limited by the background noise of the universe. However, the size of these detector arrays are limited to only a few thousand pixels. This is because of the cost and complexity of fabricating large-scale arrays of these detectors that can reach up to 10 lithographic levels on chip, and the complicated SQUID-based multiplexing circuitry and wiring for readout of each detector. In order to make substantial progress, next-generation ground-based telescopes such as CCAT or future space telescopes require focal planes with large-scale detector arrays of 104--10 6 pixels. Arrays using microwave kinetic inductance detectors (MKID) are a potential solution. These arrays can be easily made with a single layer of superconducting metal film deposited on a silicon substrate and pattered using conventional optical lithography. Furthermore, MKIDs are inherently multiplexable in the frequency domain, allowing ˜ 10 3 detectors to be read out using a single coaxial transmission line and cryogenic amplifier, drastically reducing cost and complexity. An MKID uses the change in the microwave surface impedance of a superconducting thin-film microresonator to detect photons. Absorption of photons in the superconductor breaks Cooper pairs into quasiparticles, changing the complex surface impedance, which results in a perturbation of resonator frequency and quality factor. For excitation and readout, the resonator is weakly coupled to a transmission line. The complex amplitude of a microwave probe signal tuned on-resonance and transmitted on the feedline past the resonator is perturbed as photons are absorbed in the superconductor. The perturbation can be

  20. Logarithmic current-measuring transistor circuits

    DEFF Research Database (Denmark)

    Højberg, Kristian Søe

    1967-01-01

    Describes two transistorized circuits for the logarithmic measurement of small currents suitable for nuclear reactor instrumentation. The logarithmic element is applied in the feedback path of an amplifier, and only one dual transistor is used as logarithmic diode and temperature compensating...... transistor. A simple one-amplifier circuit is compared with a two-amplifier system. The circuits presented have been developed in connexion with an amplifier using a dual m.o.s. transistor input stage with diode-protected gates....

  1. The point of practical use for the transistor circuit

    International Nuclear Information System (INIS)

    1996-01-01

    This is comprised of eight chapters and goes as follows; what is transistor? the first step for use of transistor such as connection between power and signal source, static characteristic of transistor and equivalent circuit of transistor, design of easy small-signal amplifier circuit, design for amplification of electric power and countermeasure for prevention of trouble, transistor concerned interface, transistor circuit around micro computer, transistor in active use of FET and power circuit and transistor. It has an appendix on transistor and design of bias of FET circuits like small signal transistor circuit and FET circuit.

  2. Spectrum and isotropy of the submillimeter background radiation

    International Nuclear Information System (INIS)

    Muehlner, D.

    1977-01-01

    Two great astronomical discoveries have most shaped our present concept of the Big Bang universe. Like the Hubble recession of the galaxies, the discovery of the 3 0 K background radiation by Penzias and Wilson in 1965 has given rise to a line of research which is still very active today. Penzias and Wilson's universal microwave background at 7 cm was immediately interpreted by R.H. Dicke's group at Princeton as coming from the primordial fireball of incandescent plasma which filled the universe for the million years or so after its explosive birth. This interpretation gives rise to two crucial predictions as to the nature of the background radiation. Its spectrum should be thermal even after having been red shifted by a factor of approximately 1000 by the expansion of the universe, and the radiation should be isotropic - assuming that the universe itself is isotropic. If the background radiation is indeed from the primordial fireball it affords us the only direct view at the very young universe. This paper deals with the spectrum and then the isotropy of the background radiation, with emphasis on high frequency or submillimeter measurements. Prospects for the future are discussed briefly. (Auth.)

  3. Submillimeter Spectroscopy of the R Coronae Australis Molecular Cloud Region

    Science.gov (United States)

    Dunn, Marina Madeline; Walker, Christopher K.; Pat, Terrance; Sirsi, Siddhartha; Swift, Brandon J.; Peters, William L.

    2018-01-01

    The Interstellar Medium is comprised of large amounts of gas and dust which coalesce to form stars. Observing in the Terahertz regime of the electromagnetic spectrum, approximately 0.3 -300 microns, allows astronomers to study the ISM in unprecedented detail. Using the high spectral resolution imaging system of the SuperCam receiver, a 64-pixel array previously installed on the Submillimeter Telescope on Mt. Graham, AZ, we have begun a 500 square degree survey of the galactic plane. This instrument was designed to do a complete survey of the Milky Way from the ground, with the main focus being to observe two specific transitions of the carbon monoxide molecule, 12CO(3-2) and 13CO(3-2), at 345 GHz. In this work, we present results from these observations for the R Coronae Australis (R Cr A) complex, a region in the southern hemisphere of the sky, using spectroscopic data from a portion of the survey to gain better insight into the life cycle of the ISM. The majority of stars being formed here are similar to the stellar class of the Sun, making it an excellent area of observing interest. Using these results, we attempt to better ascertain the large-scale structure and kinematics inside of the molecular cloud.

  4. AzTEC on ASTE Survey of Submillimeter Galaxies

    Science.gov (United States)

    Kohno, K.; Tamura, Y.; Hatsukade, B.; Nakanishi, K.; Iono, D.; Takata, T.; Wilson, G. W.; Yun, M. S.; Perera, T.; Austermann, J. E.; Scott, K. S.; Hughes, H.; Aretxaga, I.; Tanaka, K.; Oshima, T.; Yamaguchi, N.; Matsuo, H.; Ezawa, H.; Kawabe, R.

    2008-10-01

    We have conducted an unprecedented survey of submillimeter galaxies (SMGs) using the 144 pixel bolometer camera AzTEC mounted on the ASTE 10-m dish in Chile. We have already obtained many (>20) wide (typically 12' × 12' or wider) and deep (1 σ sensitivity of 0.5-1.0 mJy) 1.1 mm continuum images of known blank fields and over-density regions/protoclusters across a wide range of redshifts with a spatial resolution of ˜ 30''. It has resulted in the numerous (˜ a few 100, almost equivalent to the total number of the previously known SMGs) new and secure detections of SMGs. In this paper, we present initial results of two selected fields, SSA 22 and AKARI Deep Field South (ADF-S). A significnat clustering of bright SMGs toward the density peak of LAEs is found in SSA 22. We derived the differential and cumulative number counts from the detected sources in ADF-S, which probe the faintest flux densities (down to ˜1 mJy) among 1-mm blank field surveys to date.

  5. Transistor challenges - A DRAM perspective

    International Nuclear Information System (INIS)

    Faul, Juergen W.; Henke, Dietmar

    2005-01-01

    Key challenges of the transistor scaling from a DRAM perspective will be reviewed. Both, array transistors as well as DRAM support devices face challenges that differ essentially from high performance logic device scaling. As a major difference, retention time and standby current requirements characterize special boundary conditions in the DRAM device design. Array device scaling is determined by a chip size driven aggressive node scaling. To continue scaling, major innovations need to be introduced into state-of-the-art planar array transistors. Alternatively, non planar device concepts will have to be evaluated. Support device design for DRAMs is driven by today's market demand for increased chip performances at little to no extra cost. Major innovations are required to continue that path. Besides this strive for performance increase, special limitations for 'on pitch' circuits at the array edge will come up due to the aggressive cell size scaling

  6. Magnetic Vortex Based Transistor Operations

    Science.gov (United States)

    Kumar, D.; Barman, S.; Barman, A.

    2014-01-01

    Transistors constitute the backbone of modern day electronics. Since their advent, researchers have been seeking ways to make smaller and more efficient transistors. Here, we demonstrate a sustained amplification of magnetic vortex core gyration in coupled two and three vortices by controlling their relative core polarities. This amplification is mediated by a cascade of antivortex solitons travelling through the dynamic stray field. We further demonstrated that the amplification can be controlled by switching the polarity of the middle vortex in a three vortex sequence and the gain can be controlled by the input signal amplitude. An attempt to show fan–out operation yielded gain for one of the symmetrically placed branches which can be reversed by switching the core polarity of all the vortices in the network. The above observations promote the magnetic vortices as suitable candidates to work as stable bipolar junction transistors (BJT). PMID:24531235

  7. Electrically controlled wire-channel GaN/AlGaN transistor for terahertz plasma applications

    Science.gov (United States)

    Cywiński, G.; Yahniuk, I.; Kruszewski, P.; Grabowski, M.; Nowakowski-Szkudlarek, K.; Prystawko, P.; Sai, P.; Knap, W.; Simin, G. S.; Rumyantsev, S. L.

    2018-03-01

    We report on a design of fin-shaped channel GaN/AlGaN field-effect transistors developed for studying resonant terahertz plasma oscillations. Unlike common two dimensional FinFET transistor design, the gates were deposited only to the sides of the two dimensional electron gas channel, i.e., metal layers were not deposited on the top of the AlGaN. This side gate configuration allowed us to electrically control the conductivity of the channel by changing its width while keeping the carrier density and mobility virtually unchanged. Computer simulations and analytical model describe well the general shape of the characteristics. The side gate control of the channel width of these transistors allowed us to eliminate the so-called oblique plasma wave modes and paves the way towards future terahertz detectors and emitters using high quality factor plasma wave resonances.

  8. Mapping brain activity with flexible graphene micro-transistors

    Science.gov (United States)

    Blaschke, Benno M.; Tort-Colet, Núria; Guimerà-Brunet, Anton; Weinert, Julia; Rousseau, Lionel; Heimann, Axel; Drieschner, Simon; Kempski, Oliver; Villa, Rosa; Sanchez-Vives, Maria V.; Garrido, Jose A.

    2017-06-01

    Establishing a reliable communication interface between the brain and electronic devices is of paramount importance for exploiting the full potential of neural prostheses. Current microelectrode technologies for recording electrical activity, however, evidence important shortcomings, e.g. challenging high density integration. Solution-gated field-effect transistors (SGFETs), on the other hand, could overcome these shortcomings if a suitable transistor material were available. Graphene is particularly attractive due to its biocompatibility, chemical stability, flexibility, low intrinsic electronic noise and high charge carrier mobilities. Here, we report on the use of an array of flexible graphene SGFETs for recording spontaneous slow waves, as well as visually evoked and also pre-epileptic activity in vivo in rats. The flexible array of graphene SGFETs allows mapping brain electrical activity with excellent signal-to-noise ratio (SNR), suggesting that this technology could lay the foundation for a future generation of in vivo recording implants.

  9. Understanding noise suppression in heterojunction field-effect transistors

    International Nuclear Information System (INIS)

    Green, F.

    1996-01-01

    Full text: The enhanced transport properties displayed by quantum-well-confined, two-dimensional, electron systems underpin the success of heterojunction, field-effect transistors. At cryogenic temperatures, these devices exhibit impressive mobilities and, as a result, high signal gain and low noise. Conventional wisdom has it that the same favourable conditions also hold for normal room-temperature operation. In that case, however, high mobilities are precluded by abundant electron-phonon scattering. Our recent study of nonequilibrium current noise shows that quantum confinement, not high mobility, is the principal source of noise in these devices; this opens up new and exciting opportunities in low-noise transistor design. As trends in millimetre-wave technology push frequencies beyond 100 GHz, it is essential to develop a genuine understanding of noise processes in heterojunction devices

  10. Tunneling field effect transistor technology

    CERN Document Server

    Chan, Mansun

    2016-01-01

    This book provides a single-source reference to the state-of-the art in tunneling field effect transistors (TFETs). Readers will learn the TFETs physics from advanced atomistic simulations, the TFETs fabrication process and the important roles that TFETs will play in enabling integrated circuit designs for power efficiency. · Provides comprehensive reference to tunneling field effect transistors (TFETs); · Covers all aspects of TFETs, from device process to modeling and applications; · Enables design of power-efficient integrated circuits, with low power consumption TFETs.

  11. Photon-gated spin transistor

    OpenAIRE

    Li, Fan; Song, Cheng; Cui, Bin; Peng, Jingjing; Gu, Youdi; Wang, Guangyue; Pan, Feng

    2017-01-01

    Spin-polarized field-effect transistor (spin-FET), where a dielectric layer is generally employed for the electrical gating as the traditional FET, stands out as a seminal spintronic device under the miniaturization trend of electronics. It would be fundamentally transformative if optical gating was used for spin-FET. We report a new type of spin-polarized field-effect transistor (spin-FET) with optical gating, which is fabricated by partial exposure of the (La,Sr)MnO3 channel to light-emitti...

  12. Programmable, automated transistor test system

    Science.gov (United States)

    Truong, L. V.; Sundburg, G. R.

    1986-01-01

    A programmable, automated transistor test system was built to supply experimental data on new and advanced power semiconductors. The data will be used for analytical models and by engineers in designing space and aircraft electric power systems. A pulsed power technique was used at low duty cycles in a nondestructive test to examine the dynamic switching characteristic curves of power transistors in the 500 to 1000 V, 10 to 100 A range. Data collection, manipulation, storage, and output are operator interactive but are guided and controlled by the system software.

  13. Silicon on insulator self-aligned transistors

    Science.gov (United States)

    McCarthy, Anthony M.

    2003-11-18

    A method for fabricating thin-film single-crystal silicon-on-insulator (SOI) self-aligned transistors. Standard processing of silicon substrates is used to fabricate the transistors. Physical spaces, between the source and gate, and the drain and gate, introduced by etching the polysilicon gate material, are used to provide connecting implants (bridges) which allow the transistor to perform normally. After completion of the silicon substrate processing, the silicon wafer is bonded to an insulator (glass) substrate, and the silicon substrate is removed leaving the transistors on the insulator (glass) substrate. Transistors fabricated by this method may be utilized, for example, in flat panel displays, etc.

  14. On theory of single-molecule transistor

    International Nuclear Information System (INIS)

    Tran Tien Phuc

    2009-01-01

    The results of the study on single-molecule transistor are mainly investigated in this paper. The structure of constructed single-molecule transistor is similar to a conventional MOSFET. The conductive channel of the transistors is a single-molecule of halogenated benzene derivatives. The chemical simulation software CAChe was used to design and implement for the essential parameter of the molecules utilized as the conductive channel. The GUI of Matlab has been built to design its graphical interface, calculate and plot the output I-V characteristic curves for the transistor. The influence of temperature, length and width of the conductive channel, and gate voltage is considered. As a result, the simulated curves are similar to the traditional MOSFET's. The operating temperature range of the transistors is wider compared with silicon semiconductors. The supply voltage for transistors is only about 1 V. The size of transistors in this research is several nanometers.

  15. Analysing organic transistors based on interface approximation

    International Nuclear Information System (INIS)

    Akiyama, Yuto; Mori, Takehiko

    2014-01-01

    Temperature-dependent characteristics of organic transistors are analysed thoroughly using interface approximation. In contrast to amorphous silicon transistors, it is characteristic of organic transistors that the accumulation layer is concentrated on the first monolayer, and it is appropriate to consider interface charge rather than band bending. On the basis of this model, observed characteristics of hexamethylenetetrathiafulvalene (HMTTF) and dibenzotetrathiafulvalene (DBTTF) transistors with various surface treatments are analysed, and the trap distribution is extracted. In turn, starting from a simple exponential distribution, we can reproduce the temperature-dependent transistor characteristics as well as the gate voltage dependence of the activation energy, so we can investigate various aspects of organic transistors self-consistently under the interface approximation. Small deviation from such an ideal transistor operation is discussed assuming the presence of an energetically discrete trap level, which leads to a hump in the transfer characteristics. The contact resistance is estimated by measuring the transfer characteristics up to the linear region

  16. Sub-millimeter science with the Heinrich-Hertz-Telescope

    Science.gov (United States)

    Dumke, Michael

    The Heinrich-Hertz-Telescope on Mt. Graham, Arizona, is a state-of-the-art single-dish radio telescope for observations in the sub-millimeter wavelength range. It is operated by the Sub-Millimeter Telescope Observatory (SMTO), which is a collaboration between the University of Arizona, Tucson, and the Max-Planck-Institut für Radioastronomie, Bonn. In this talk I give an overview over the telescope and its instrumentation, and show some examples of forefront research performed by astronomers from both the U.S. and Europe using this instrument. The telescope is located on Mt. Graham, Arizona, at an altitude of 3178 m, which ensures sub-mm weather conditions during a significant amount of available observing time. It has a primary reflector of 10 m diameter, mounted on a carbon fiber backup structure, and is equipped with a corotating enclosure. The surface accuracy of the primary reflector is 12 microns rms, what makes the HHT the most accurate radio telescope ever built. For spectral line observations, SIS receivers covering the frequency range from 200 to 500 GHz are available. Furthermore, a Hot-Electron-Bolometer, developed at the CfA, can be used for spectral line observations above 800 GHz. The continuum receivers are a 4-color bolometer, observing at 1300, 870, 450, and 350 microns, and a 19-channel bolometer array, developed at the MPIfR, which is sensitive around 850 microns. In the last few years, the HHT has been used by several groups to perform astronomical research. The most notable result was the measurement of the CO(9--8) line in Orion at 1.037 THz with the Hot-Electron Bolometer -- the first radioastronomical observation above 1 THz from a ground-based telescope. Several galactic molecular line sources have been mapped in the CO(7--6) line at 806 GHz, and in two fine-structure lines of atomic carbon. A continuum map of the galactic center at 850 microns could be produced using the new 19-channel bolometer array. Even external galaxies, where

  17. SUBMILLIMETER POLARIZATION OBSERVATION OF THE PROTOPLANETARY DISK AROUND HD 142527

    Energy Technology Data Exchange (ETDEWEB)

    Kataoka, Akimasa; Dullemond, Cornelis P.; Pohl, Adriana [Zentrum für Astronomie der Universität Heidelberg, Institut für Theoretische Astrophysik, Albert-Ueberle-Str. 2, D-69120 Heidelberg (Germany); Tsukagoshi, Takashi; Momose, Munetake [College of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512 (Japan); Nagai, Hiroshi [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Muto, Takayuki [Division of Liberal Arts, Kogakuin University, 1-24-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo 163-8677 (Japan); Fukagawa, Misato [Division of Particle and Astrophysical Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602 (Japan); Shibai, Hiroshi [Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 (Japan); Hanawa, Tomoyuki [Center for Frontier Science, Chiba University, 1-33 Yayoi-cho, Inage, Chiba 263-8522 (Japan); Murakawa, Koji, E-mail: kataoka@uni-heidelberg.de [College of General Education, Osaka Sangyo University, 3-1-1, Nakagaito, Daito, Osaka 574-8530 (Japan)

    2016-11-10

    We present the polarization observations toward the circumstellar disk around HD 142527 by using Atacama Large Millimeter/submillimeter Array at the frequency of 343 GHz. The beam size is 0.″51 × 0.″44, which corresponds to the spatial resolution of ∼71 × 62 au. The polarized intensity displays a ring-like structure with a peak located on the east side with a polarization fraction of P = 3.26 ± 0.02%, which is different from the peak of the continuum emission from the northeast region. The polarized intensity is significantly weaker at the peak of the continuum where P = 0.220 ± 0.010%. The polarization vectors are in the radial direction in the main ring of the polarized intensity, while there are two regions outside at the northwest and northeast areas where the vectors are in the azimuthal direction. If the polarization vectors represent the magnetic field morphology, the polarization vectors indicate the toroidal magnetic field configuration on the main ring and the poloidal fields outside. On the other hand, the flip of the polarization vectors is predicted by the self-scattering of thermal dust emission due to the change of the direction of thermal radiation flux. Therefore, we conclude that self-scattering of thermal dust emission plays a major role in producing polarization at millimeter wavelengths in this protoplanetary disk. Also, this puts a constraint on the maximum grain size to be approximately 150 μ m if we assume compact spherical dust grains.

  18. HERSCHEL/SPIRE SUBMILLIMETER SPECTRA OF LOCAL ACTIVE GALAXIES {sup ,}

    Energy Technology Data Exchange (ETDEWEB)

    Pereira-Santaella, Miguel; Spinoglio, Luigi; Busquet, Gemma [Istituto di Astrofisica e Planetologia Spaziali, INAF, Via Fosso del Cavaliere 100, I-00133 Roma (Italy); Wilson, Christine D.; Schirm, Maximilien R. P. [Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1 (Canada); Glenn, Jason; Kamenetzky, Julia; Rangwala, Naseem [Center for Astrophysics and Space Astronomy, 389-UCB, University of Colorado, Boulder, CO 80303 (United States); Isaak, Kate G. [ESA Astrophysics Missions Division, ESTEC, P.O. Box 299, 2200 AG Noordwijk (Netherlands); Baes, Maarten [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, B-9000 Gent (Belgium); Barlow, Michael J. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Boselli, Alessandro [Laboratoire d' Astrophysique de Marseille (LAM), Universite d' Aix-Marseille and CNRS, UMR7326, 38 rue F. Joliot-Curie, F-13388 Marseille Cedex 13 (France); Cooray, Asantha [Center for Cosmology, Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Cormier, Diane, E-mail: miguel.pereira@ifsi-roma.inaf.it [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, Irfu/Service d' Astrophysique, CEA Saclay, F-91191 Gif-sur-Yvette (France)

    2013-05-01

    We present the submillimeter spectra from 450 to 1550 GHz of 11 nearby active galaxies observed with the SPIRE Fourier Transform Spectrometer (SPIRE/FTS) on board Herschel. We detect CO transitions from J{sub up} = 4 to 12, as well as the two [C I] fine structure lines at 492 and 809 GHz and the [N II]1461 GHz line. We used radiative transfer models to analyze the observed CO spectral line energy distributions. The FTS CO data were complemented with ground-based observations of the low-J CO lines. We found that the warm molecular gas traced by the mid-J CO transitions has similar physical conditions (n{sub H{sub 2}}{approx} 10{sup 3.2}-10{sup 3.9} cm{sup -3} and T{sub kin} {approx} 300-800 K) in most of our galaxies. Furthermore, we found that this warm gas is likely producing the mid-IR rotational H{sub 2} emission. We could not determine the specific heating mechanism of the warm gas, however, it is possibly related to the star formation activity in these galaxies. Our modeling of the [C I] emission suggests that it is produced in cold (T{sub kin} < 30 K) and dense (n{sub H{sub 2}}>10{sup 3} cm{sup -3}) molecular gas. Transitions of other molecules are often detected in our SPIRE/FTS spectra. The HF J = 1-0 transition at 1232 GHz is detected in absorption in UGC 05101 and in emission in NGC 7130. In the latter, near-infrared pumping, chemical pumping, or collisional excitation with electrons are plausible excitation mechanisms likely related to the active galactic nucleus of this galaxy. In some galaxies, few H{sub 2}O emission lines are present. Additionally, three OH{sup +} lines at 909, 971, and 1033 GHz are identified in NGC 7130.

  19. EVIDENCE FOR DUST CLEARING THROUGH RESOLVED SUBMILLIMETER IMAGING

    International Nuclear Information System (INIS)

    Brown, J. M.; Blake, G. A.; Qi, C.; Wilner, D. J.; Dullemond, C. P.; Williams, J. P.

    2009-01-01

    Mid-infrared spectrophotometric observations have revealed a small subclass of circumstellar disks with spectral energy distributions (SEDs) suggestive of large inner gaps with low dust content. However, such data provide only an indirect and model-dependent method of finding central holes. Imaging of protoplanetry disks provides an independent check of SED modeling. We present here the direct characterization of three 33-47 AU radii inner gaps, in the disks around LkHα 330, SR 21N, and HD 135344B, via 340 GHz (880 μm) dust continuum aperture synthesis observations obtained with the Submillimeter Array (SMA). The large gaps are fully resolved at ∼0.''3 by the SMA data and mostly empty of dust, with less than (1-7.5) x 10 -6 M sun of fine grained solids inside the holes. Gas (as traced by atomic accretion markers and CO 4.7 μm rovibrational emission) is still present in the inner regions of all three disks. For each, the inner hole exhibits a relatively steep rise in dust emission to the outer disk, a feature more likely to originate from the gravitational influence of a companion body than from a process expected to show a more shallow gradient like grain growth. Importantly, the good agreement between the spatially resolved data and spectrophotometry-based models lends confidence to current interpretations of SEDs, wherein the significant dust emission deficits arise from disks with inner gaps or holes. Further SED-based searches can therefore be expected to yield numerous additional candidates that can be examined at high spatial resolution.

  20. The Digital Motion Control System for the Submillimeter Array Antennas

    Science.gov (United States)

    Hunter, T. R.; Wilson, R. W.; Kimberk, R.; Leiker, P. S.; Patel, N. A.; Blundell, R.; Christensen, R. D.; Diven, A. R.; Maute, J.; Plante, R. J.; Riddle, P.; Young, K. H.

    2013-09-01

    We describe the design and performance of the digital servo and motion control system for the 6-meter parabolic antennas of the Submillimeter Array (SMA) on Mauna Kea, Hawaii. The system is divided into three nested layers operating at a different, appropriate bandwidth. (1) A rack-mounted, real-time Unix system runs the position loop which reads the high resolution azimuth and elevation encoders and sends velocity and acceleration commands at 100 Hz to a custom-designed servo control board (SCB). (2) The microcontroller-based SCB reads the motor axis tachometers and implements the velocity loop by sending torque commands to the motor amplifiers at 558 Hz. (3) The motor amplifiers implement the torque loop by monitoring and sending current to the three-phase brushless drive motors at 20 kHz. The velocity loop uses a traditional proportional-integral-derivative (PID) control algorithm, while the position loop uses only a proportional term and implements a command shaper based on the Gauss error function. Calibration factors and software filters are applied to the tachometer feedback prior to the application of the servo gains in the torque computations. All of these parameters are remotely adjustable in the software. The three layers of the control system monitor each other and are capable of shutting down the system safely if a failure or anomaly occurs. The Unix system continuously relays the antenna status to the central observatory computer via reflective memory. In each antenna, a Palm Vx hand controller displays the complete system status and allows full local control of the drives in an intuitive touchscreen user interface. The hand controller can also be connected outside the cabin, a major convenience during the frequent reconfigurations of the interferometer. Excellent tracking performance ( 0.3‧‧ rms) is achieved with this system. It has been in reliable operation on 8 antennas for over 10 years and has required minimal maintenance.

  1. SPATIALLY RESOLVED SPECTROSCOPY OF SUBMILLIMETER GALAXIES AT z ≃ 2

    Energy Technology Data Exchange (ETDEWEB)

    Olivares, V.; Treister, E.; Privon, G. C.; Nagar, N. [Universidad de Concepción, Departamento de Astronomía, Casilla 160-C, Concepción (Chile); Alaghband-Zadeh, S.; Chapman, S. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA UK (United Kingdom); Casey, Caitlin M. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Schawinski, K. [Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland); Kurczynski, P.; Gawiser, E. [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Bauer, F. E. [Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22 (Chile); Sanders, D. [Institute for Astronomy, 2680 Woodlawn Drive, University of Hawaii, Honolulu, HI 96822 (United States)

    2016-08-10

    We present near-infrared integral-field spectroscopic observations targeting H α in eight submillimeter galaxies (SMGs) at z = 1.3–2.5 using the Very Large Telescope/Spectrograph for Integral Field Observations in the Near Infrared, obtaining significant detections for six of them. The star formation rates derived from the H α emission are ∼100 M {sub ⊙} yr{sup −1}, which account for only ∼20%–30% of the infrared-derived values, thus suggesting that these systems are very dusty. Two of these systems present [N ii]/H α ratios indicative of the presence of an active galactic nucleus. We mapped the spatial distribution and kinematics of the star-forming regions in these galaxies on kiloparsec scales. In general, the H α morphologies tend to be highly irregular and/or clumpy, showing spatial extents of ∼3–11 kpc. We find evidence for significant spatial offsets, of ∼0.″1–0.″4 or 1.2–3.4 kpc, between the H α and the continuum emission in three of the sources. Performing a kinemetry analysis, we conclude that the majority of the sample is not consistent with disk-like rotation-dominated kinematics. Instead, they tend to show irregular and/or clumpy and turbulent velocity and velocity dispersion fields. This can be interpreted as evidence for a scenario in which these extreme star formation episodes are triggered by galaxy–galaxy interactions and major mergers. In contrast to recent results for SMGs, these sources appear to follow the same relations between gas and star-forming rate densities as less luminous and/or normal star-forming galaxies.

  2. A High-Voltage Level Tolerant Transistor Circuit

    NARCIS (Netherlands)

    Annema, Anne J.; Geelen, Godefridus Johannes Gertrudis Maria

    2001-01-01

    A high-voltage level tolerant transistor circuit, comprising a plurality of cascoded transistors, including a first transistor (T1) operatively connected to a high-voltage level node (3) and a second transistor (T2) operatively connected to a low-voltage level node (2). The first transistor (T1)

  3. Josephson junction spectrum analyzer for millimeter and submillimeter wavelengths

    International Nuclear Information System (INIS)

    Larkin, S.Y.; Anischenko, S.E.; Khabayev, P.V.

    1994-01-01

    A prototype of the Josephson-effect spectrum analyzer developed for the millimeter-wave band is described. The measurement results for spectra obtained in the frequency band from 50 to 250 GHz are presented

  4. Josephson junction spectrum analyzer for millimeter and submillimeter wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Larkin, S.Y.; Anischenko, S.E.; Khabayev, P.V. [State Research Center, Kiev (Ukraine)

    1994-12-31

    A prototype of the Josephson-effect spectrum analyzer developed for the millimeter-wave band is described. The measurement results for spectra obtained in the frequency band from 50 to 250 GHz are presented.

  5. Photonic band gap materials: towards an all-optical transistor

    Science.gov (United States)

    Florescu, Marian

    2002-05-01

    The transmission of information as optical signals encoded on light waves traveling through optical fibers and optical networks is increasingly moving to shorter and shorter distance scales. In the near future, optical networking is poised to supersede conventional transmission over electric wires and electronic networks for computer-to-computer communications, chip-to-chip communications, and even on-chip communications. The ever-increasing demand for faster and more reliable devices to process the optical signals offers new opportunities in developing all-optical signal processing systems (systems in which one optical signal controls another, thereby adding "intelligence" to the optical networks). All-optical switches, two-state and many-state all-optical memories, all-optical limiters, all-optical discriminators and all-optical transistors are only a few of the many devices proposed during the last two decades. The "all-optical" label is commonly used to distinguish the devices that do not involve dissipative electronic transport and require essentially no electrical communication of information. The all-optical transistor action was first observed in the context of optical bistability [1] and consists in a strong differential gain regime, in which, for small variations in the input intensity, the output intensity has a very strong variation. This analog operation is for all-optical input what transistor action is for electrical inputs.

  6. Micro-Spec: A High Performance Compact Spectrometer for Submillimeter Astronomy

    Science.gov (United States)

    Hsieh, Wen-Ting; Moseley, Harvey; Stevenson, Thomas; Brown, Ari; Patel, Amil; U-Yen, Kongpop; Ehsan, Negar; Caltado, Giuseppe; Wollock, Edward

    2012-01-01

    We describe the micro-Spec, an extremely compact high performance spectrometer for the submillimeter and millimeter spectral ranges. We have designed a fully integrated submillimeter spectrometer based on superconducting microstrip technology and fabricated its critical elements. Using low loss transmission lines, we can produce a fully integrated high resolution submillimeter spectrometer on a single four inch Si wafer. A resolution of 500 can readily be achieved with standard fabrication tolerance, higher with phase trimming. All functions of the spectrometer are integrated - light is coupled to the micro strip circuit with a planar antenna, the spectra discrimination is achieved using a synthetic grating, orders are separated using a built-in planar filter, and the light is detected using photon counting Microwave Kinetic Inductance Detectors (MKID). We will discus the design principle of the instrument, describe its technical advantages, and report the progress on the development of the instrument.

  7. Mu-Spec: A High Performance Compact Spectrometer for Submillimeter Astronomy

    Science.gov (United States)

    Hsieh, Wen-Ting; Moseley, Harvey; Stevenson, Thomas; Brown, Ari; Patel, Amil; U-yen, Kongpop; Ehsan, Negar; Cataldo, Giuseppe; Wollack, Ed

    2012-01-01

    We describe the Mu-Spec, an extremely compact high performance spectrometer for the submillimeter and millimeter spectral ranges. We have designed a fully integrated submillimeter spectrometer based on superconducting microstrip technology and fabricated its critical elements. Using low loss transmission lines, we can produce a fully integrated high resolution submillimeter spectrometer on a single four inch Si wafer. A resolution of 500 can readily be achieved with standard fabrication tolerance, higher with phase trimming. All functions of the spectrometer are integrated - light is coupled to the microstrip circuit with a planar antenna, the spectra discrimination is achieved using a synthetic grating, orders are separated using a built-in planar filter, and the light is detected using photon counting Microwave Kinetic Inductance Detectors (MKID). We will discus the design principle of the instrument, describe its technical advantages, and report the progress on the development of the instrument.

  8. Impact of total ionizing dose on the electromagnetic susceptibility of a single bipolar transistor

    International Nuclear Information System (INIS)

    Doridant, A.; Jarrix, S.; Raoult, J.; Blain, A.; Dusseau, L.; Chatry, N.; Calvel, P.; Hoffmann, P.

    2012-01-01

    Space or military electronic components are subject to both electromagnetic fields and total ionizing dose. This paper deals with the electromagnetic susceptibility of a discrete low frequency transistor subject to total ionizing dose deposition. The electromagnetic susceptibility is investigated on both non-irradiated and irradiated transistors mounted in common emitter configuration. The change in susceptibility to 100 MHz-1.5 GHz interferences lights up a synergy effect between near field electromagnetic waves and total ionizing dose. Physical mechanisms leading to changes in signal output are detailed. (authors)

  9. Millimeter- and submillimeter-wave spectrum and molecular constants of cuprous iodide

    International Nuclear Information System (INIS)

    Manson, E.L.; De Lucia, F.C.; Gordy, W.

    1975-01-01

    Monomeric cuprous iodide (CuI) in the vapor state has been produced as an intermediate product of the reaction of copper with iodine vapor at 1100 degreeK in a quasi-free-space microwave absorption cell. Rotational transitions of 63 Cu 127 I and 65 Cu 127 I were measured for J as high as 87→88 and for ν as high as 11. Hyperfine splittings due to 127 I were observed, and eqQ ( 127 I) =-935(15) MHz was derived. Analysis of the rotational frequencies yields the following Dunham and equilibrium coefficients for 63 Cu 127 I: Y 01 =2197.10172(98) MHz, Y 11 =-8.51120(66) MHz, Y 21 =0.00934(14) MHz, Y 31 =-0.0375(88) kHz, Y 02 =-0.67269(10) kHz, Y 12 =0.031(34) Hz, Y 03 =-0.00006858(10) Hz, B/sube/=2197.102(2) MHz, ω/sube/=264.897(18) cm -1 , ω/sube/chi/sube/=0.715(2) cm -1 , r/sube/=2.33831686(104) A; for 65 Cu 127 I: Y 01 =2151.89989(94) MHz, Y 11 =-8.24990(66) MHz, Y 21 =0.00896(14) MHz, Y 31 =-0.0356(88) kHz, Y 02 =-0.64530(10) kHz, Y 12 =0.030(34) Hz, Y 03 =-0.00006443(10) Hz, B/sube/=2151.900(2) MHz, ω/sube/=262.157(18) cm -1 , ω/sube/chi/sube/=0.700(2) cm -1 , r/sube/=2.33831664(102) A. The Dunham potential constants for CuI are a 0 =239 366(34) cm -1 , a 1 =-3.33365(36), a 2 =7.391(16), and a 3 =-13.20(18)

  10. Power transistor module for high current applications

    International Nuclear Information System (INIS)

    Cilyo, F.F.

    1975-01-01

    One of the parts needed for the control system of the 400-GeV accelerator at Fermilab was a power transistor with a safe operating area of 1800A at 50V, dc current gain of 100,000 and 20 kHz bandwidth. Since the commercially available discrete devices and power hybrid packages did not meet these requirements, a power transistor module was developed which performed satisfactorily. By connecting 13 power transistors in parallel, with due consideration for network and heat dissipation problems, and by driving these 13 with another power transistor, a super power transistor is made, having an equivalent current, power, and safe operating area capability of 13 transistors. For higher capabilities, additional modules can be conveniently added. (auth)

  11. Millimeter and submillimeter observations from the Atacama plateau and high altitude balloons

    Science.gov (United States)

    Devlin, Mark

    2002-05-01

    A new generation of ground-based and sub-orbital platforms will be operational in the next few years. These telescopes will operate from high sites in Chile and Antarctica, and airborne platforms where the atmosphere is transparent enough to allow sensitive measurements in the millimeter and submillimeter bands. The telescopes will employ state-of-the-art instrumentation including large format bolometer arrays and spectrometers. I will discuss the results of our observations in the Atacama region of Chile (MAT/TOCO), our future observations on the Balloon-borne Large Aperture Submillimeter Telescope (BLAST) now under construction, and our proposed Atacama Cosmology Telescope (ACT). .

  12. Principles of an atomtronic transistor

    International Nuclear Information System (INIS)

    Caliga, Seth C; Anderson, Dana Z; Straatsma, Cameron J E; Zozulya, Alex A

    2016-01-01

    A semiclassical formalism is used to investigate the transistor-like behavior of ultracold atoms in a triple-well potential. Atom current flows from the source well, held at fixed chemical potential and temperature, into an empty drain well. In steady-state, the gate well located between the source and drain is shown to acquire a well-defined chemical potential and temperature, which are controlled by the relative height of the barriers separating the three wells. It is shown that the gate chemical potential can exceed that of the source and have a lower temperature. In electronics terminology, the source–gate junction can be reverse-biased. As a result, the device exhibits regimes of negative resistance and transresistance, indicating the presence of gain. Given an external current input to the gate, transistor-like behavior is characterized both in terms of the current gain, which can be greater than unity, and the power output of the device. (paper)

  13. High current transistor pulse generator

    International Nuclear Information System (INIS)

    Nesterov, V.; Cassel, R.

    1991-05-01

    A solid state pulse generator capable of delivering high current trapezoidally shaped pulses into an inductive load has been developed at SLAC. Energy stored in the capacitor bank of the pulse generator is switched to the load through a pair of Darlington transistors. A combination of diodes and Darlington transistors is used to obtain trapezoidal or triangular shaped current pulses into an inductive load and to recover the remaining energy in the same capacitor bank without reversing capacitor voltage. The transistors work in the switch mode, and the power losses are low. The rack mounted pulse generators presently used at SLAC contain a 660 microfarad storage capacitor bank and can deliver 400 amps at 800 volts into inductive loads up to 3 mH. The pulse generators are used in several different power systems, including pulse to pulse bipolar power supplies and in application with current pulses distributed into different inductive loads. The current amplitude and discharge time are controlled by the central computer system through a specially developed multichannel controller. Several years of operation with the pulse generators have proven their consistent performance and reliability. 8 figs

  14. Impact of Process Technologies on ELDRS of Bipolar Transistors

    International Nuclear Information System (INIS)

    Lu Wu; Ren Diyuan; Guo Qi; Yu Xuefeng; Zheng Yuzhan

    2010-01-01

    Radiation effects under different dose rates and annealing behaviors of domestic bipolar transistors, with same manufacture technology, were investigated.These transistors include NPN transistors of various emitter area, and LPNP transistors with different doping concentrations in emitter. It is shown that different types of transistors have different radiation responses. The results of NPN transistors show that more degradation occurs at less emitter area. Yet, the results of LPNP transistors demonstrate that transistors with lightly doped emitter are more sensitive to radiation, compared with heavily doped emitter. Finally,the mechanisms of the difference between various radiation responses were analyzed. (authors)

  15. COMPACT STARBURSTS IN z similar to 3-6 SUBMILLIMETER GALAXIES REVEALED BY ALMA

    NARCIS (Netherlands)

    Ikarashi, Soh; Ivison, R. J.; Caputi, Karina I.; Aretxaga, Itziar; Dunlop, James S.; Hatsukade, Bunyo; Hughes, David H.; Iono, Daisuke; Izumi, Takuma; Kawabe, Ryohei; Kohno, Kotaro; Lagos, Claudia D. P.; Motohara, Kentaro; Nakanishi, Kouichiro; Ohta, Kouji; Tamura, Yoichi; Umehata, Hideki; Wilson, Grant W.; Yabe, Kiyoto; Yun, Min S.

    2015-01-01

    We report the source size distribution, as measured by ALMA millimetric continuum imaging, of a sample of 13 AzTEC-selected submillimeter galaxies (SMGs) at z(phot) similar to 3-6. Their infrared luminosities and star formation rates (SFRs) are L-IR similar to, 2-6 x 10(12) L-circle dot and similar

  16. QUANTUM ELECTRONIC DEVICES: Superconducting Nb3Sn point contact in the submillimeter range of electromagnetic radiation

    Science.gov (United States)

    Belenov, É. M.; Danileĭko, M. V.; Derkach, V. E.; Romanenko, V. I.; Uskov, A. V.

    1988-05-01

    An investigation was made of the influence of submillimeter radiation emitted by an HCN laser operating at a frequency νl = 891 GHz on a superconducting point contact made of Nb3Sn. Three steps of the electric current were recorded. The experimental results indicated that such a contact could be used for frequency multiplication up to 3 THz.

  17. ON THE EFFECT OF THE COSMIC MICROWAVE BACKGROUND IN HIGH-REDSHIFT (SUB-)MILLIMETER OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Da Cunha, Elisabete; Groves, Brent; Walter, Fabian; Decarli, Roberto; Rix, Hans-Walter [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Weiss, Axel [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Bertoldi, Frank [Argelander Institute for Astronomy, University of Bonn, Auf dem Huegel 71, D-53121 Bonn (Germany); Carilli, Chris [National Radio Astronomy Observatory, Pete V. Domenici Array Science Center, P.O. Box O, Socorro, NM 87801 (United States); Daddi, Emanuele; Sargent, Mark [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, Irfu/Service d' Astrophysique, CEA Saclay, Orme des Merisiers, F-91191 Gif-sur-Yvette Cedex (France); Elbaz, David; Ivison, Rob [UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Maiolino, Roberto [Cavendish Laboratory, University of Cambridge, 19 J. J. Thomson Avenue, Cambridge, CB3 0HE (United Kingdom); Riechers, Dominik [Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States); Smail, Ian, E-mail: cunha@mpia.de [Institute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE (United Kingdom)

    2013-03-20

    Modern (sub-)millimeter interferometers enable the measurement of the cool gas and dust emission of high-redshift galaxies (z > 5). However, at these redshifts the cosmic microwave background (CMB) temperature is higher, approaching, and even exceeding, the temperature of cold dust and molecular gas observed in the local universe. In this paper, we discuss the impact of the warmer CMB on (sub-)millimeter observations of high-redshift galaxies. The CMB affects the observed (sub-)millimeter dust continuum and the line emission (e.g., carbon monoxide, CO) in two ways: (1) it provides an additional source of (both dust and gas) heating and (2) it is a non-negligible background against which the line and continuum emission are measured. We show that these two competing processes affect the way we interpret the dust and gas properties of high-redshift galaxies using spectral energy distribution models. We quantify these effects and provide correction factors to compute what fraction of the intrinsic dust (and line) emission can be detected against the CMB as a function of frequency, redshift, and temperature. We discuss implications on the derived properties of high-redshift galaxies from (sub-)millimeter data. Specifically, the inferred dust and molecular gas masses can be severely underestimated for cold systems if the impact of the CMB is not properly taken into account.

  18. 3C 220.3: A Radio Galaxy Lensing a Submillimeter Galaxy

    NARCIS (Netherlands)

    Haas, Martin; Leipski, Christian; Barthel, Peter; Wilkes, Belinda J.; Vegetti, Simona; Bussmann, R. Shane; Willner, S. P.; Westhues, Christian; Ashby, Matthew L. N.; Chini, Rolf; Clements, David L.; Fassnacht, Christopher D.; Horesh, Assaf; Klaas, Ulrich; Koopmans, Léon V. E.; Kuraszkiewicz, Joanna; Lagattuta, David J.; Meisenheimer, Klaus; Stern, Daniel; Wylezalek, Dominika

    2014-01-01

    Herschel Space Observatory photometry and extensive multiwavelength follow-up have revealed that the powerful radio galaxy (PRG) 3C 220.3 at z = 0.685 acts as a gravitational lens for a background submillimeter galaxy (SMG) at z = 2.221. At an observed wavelength of 1 mm, the SMG is lensed into

  19. Design procedure for millimeter-wave InP DHBT stacked power amplifiers

    DEFF Research Database (Denmark)

    Squartecchia, Michele; Johansen, Tom Keinicke; Midili, Virginio

    2015-01-01

    The stacked-transistor concept for power amplifiers (PA) has been investigated in this work. Specifically, this architecture has been applied in the design of millimeter-wave monolithic microwave integrated circuits (MMICs) using indium phosphide (InP) double heterojunction bipolar transistors...

  20. Improvements in or relating to transistor circuits

    International Nuclear Information System (INIS)

    Richards, R.F.; Williamson, P.W.

    1978-01-01

    This invention relates to transistor circuits and in particular to integrated transistor circuits formed on a substrate of semi-conductor material such as silicon. The invention is concerned with providing integrated circuits in which malfunctions caused by the effects of ionising, e.g. nuclear, radiations are reduced. (author)

  1. Ultrasmall transistor-based light sources

    DEFF Research Database (Denmark)

    With Jensen, Per Baunegaard; Tavares, Luciana; Kjelstrup-Hansen, Jakob

    Dette projekt fokuserer på at udvikle transistor baserede nanofiber lyskilder med det overordnede mål at udvikle effektive og nano skalerede flerfarvede lyskilder integreret on-chip.......Dette projekt fokuserer på at udvikle transistor baserede nanofiber lyskilder med det overordnede mål at udvikle effektive og nano skalerede flerfarvede lyskilder integreret on-chip....

  2. Efficient simulation of power MOS transistors

    NARCIS (Netherlands)

    Ugryumova, M.; Schilders, W.H.A.

    2011-01-01

    In this report we present a few industrial problems related to modeling of MOS transistors. We suggest an efficient algorithm for computing output current at the top ports of power MOS transistors for given voltage excitations. The suggested algorithm exploits the connection between the resistor and

  3. Submillimeter Diameter Poly(Vinyl Alcohol) Vascular Graft Patency in Rabbit Model

    Science.gov (United States)

    Cutiongco, Marie F. A.; Kukumberg, Marek; Peneyra, Jonnathan L.; Yeo, Matthew S.; Yao, Jia Y.; Rufaihah, Abdul Jalil; Le Visage, Catherine; Ho, Jackie Pei; Yim, Evelyn K. F.

    2016-01-01

    Microvascular surgery is becoming a prevalent surgical practice. Replantation, hand reconstruction, orthopedic, and free tissue transfer procedures all rely on microvascular surgery for the repair of venous and arterial defects at the millimeter and submillimeter levels. Often, a vascular graft is required for the procedure as a means to bridge the gap between native arteries. While autologous vessels are desired for their bioactivity and non-thrombogenicity, the tedious harvest process, lack of availability, and caliber or mechanical mismatch contribute to graft failure. Thus, there is a need for an off-the-shelf artificial vascular graft that has low thrombogenic properties and mechanical properties matching those of submillimeter vessels. Poly(vinyl alcohol) hydrogel (PVA) has excellent prospects as a vascular graft due to its bioinertness, low thrombogenicity, high water content, and tunable mechanical properties. Here, we fabricated PVA grafts with submillimeter diameter and mechanical properties that closely approximated those of the rabbit femoral artery. In vitro platelet adhesion and microparticle release assay verified the low thrombogenicity of PVA. A stringent proof-of-concept in vivo test was performed by implanting PVA grafts in rabbit femoral artery with multilevel arterial occlusion. Laser Doppler measurements indicated the improved perfusion of the distal limb after implantation with PVA grafts. Moreover, ultrasound Doppler and angiography verified that the submillimeter diameter PVA vascular grafts remained patent for 2 weeks without the aid of anticoagulant or antithrombotics. Endothelial cells were observed in the luminal surface of one patent PVA graft. The advantageous non-thrombogenic and tunable mechanical properties of PVA that are retained even in the submillimeter diameter dimensions support the application of this biomaterial for vascular replacement in microvascular surgery. PMID:27376059

  4. Millimeter-wave and Submillimeter-wave Spectra of Aminoacetonitrile in the Three Lowest Vibrational Excited States

    Energy Technology Data Exchange (ETDEWEB)

    Esposti, Claudio Degli; Dore, Luca; Melosso, Mattia [Dipartimento di Chimica “Giacomo Ciamician”, Università di Bologna, via Selmi 2, I-40126 Bologna (Italy); Kobayashi, Kaori [Department of Physics, Faculty of Science, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan); Fujita, Chiho; Ozeki, Hiroyuki, E-mail: ozeki@env.sci.toho-u.ac.jp [Department of Environmental Science, Faculty of Science, Toho University, 2-2-1 Miyama, Funabashi, 274-8510 (Japan)

    2017-06-01

    It is important to study possible precursors of amino acids such as glycine to enable future searches in interstellar space. Aminoacetonitrile (NH{sub 2}CH{sub 2}CN) is one of the most feasible molecules for this purpose. This molecule was already detected toward Sgr B2(N). Aminoacetonitrile has a few low-lying vibrational excited states, and transitions within these states may be found in space. In this study, the pure-rotational transitions in the three lowest vibrational states in the 80–450 GHz range have been assigned and analyzed. It was found to be very important to include Coriolis coupling between the two lowest vibrational fundamentals, while the third one was unperturbed. The partition function was evaluated considering these new results.

  5. High-Performance Vertical Organic Electrochemical Transistors.

    Science.gov (United States)

    Donahue, Mary J; Williamson, Adam; Strakosas, Xenofon; Friedlein, Jacob T; McLeod, Robert R; Gleskova, Helena; Malliaras, George G

    2018-02-01

    Organic electrochemical transistors (OECTs) are promising transducers for biointerfacing due to their high transconductance, biocompatibility, and availability in a variety of form factors. Most OECTs reported to date, however, utilize rather large channels, limiting the transistor performance and resulting in a low transistor density. This is typically a consequence of limitations associated with traditional fabrication methods and with 2D substrates. Here, the fabrication and characterization of OECTs with vertically stacked contacts, which overcome these limitations, is reported. The resulting vertical transistors exhibit a reduced footprint, increased intrinsic transconductance of up to 57 mS, and a geometry-normalized transconductance of 814 S m -1 . The fabrication process is straightforward and compatible with sensitive organic materials, and allows exceptional control over the transistor channel length. This novel 3D fabrication method is particularly suited for applications where high density is needed, such as in implantable devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Universal power transistor base drive control unit

    Science.gov (United States)

    Gale, Allan R.; Gritter, David J.

    1988-01-01

    A saturation condition regulator system for a power transistor which achieves the regulation objectives of a Baker clamp but without dumping excess base drive current into the transistor output circuit. The base drive current of the transistor is sensed and used through an active feedback circuit to produce an error signal which modulates the base drive current through a linearly operating FET. The collector base voltage of the power transistor is independently monitored to develop a second error signal which is also used to regulate base drive current. The current-sensitive circuit operates as a limiter. In addition, a fail-safe timing circuit is disclosed which automatically resets to a turn OFF condition in the event the transistor does not turn ON within a predetermined time after the input signal transition.

  7. A submillimeter heterodyne receiver and its application in astronomy

    International Nuclear Information System (INIS)

    Vliet, A.H.F. van.

    1981-01-01

    A submm heterodyne receiver for astronomical observations has been developed which operates in the frequency range between 460 and 500 GHz. An InSb hot electron bolometer is used as the mixing element. The local oscillator power is obtained by doubling the frequency of a backward wave oscillator (B.W.O.). The sideband noise of the B.W.O. has appeared to be sufficiently weak to allow its use in combination with an InSb mixer. A method of measuring the matching of the mixer to the waveguide is described and some results of measurements of B.W.O. noise are given. A general description is presented of Gaussian beam theory and this is applied to the design of the receiver optics. Particular attention is given to the coupling between the receiver and the telescope. To prevent the usually troublesome effects of standing waves between the receiver and the telescope a circular polarizer can be applied. A review is given of different types of such polarizers as presently used in the optical and microwave regimes, with a view to their application in the submm range. Two types of circular polarizers were constructed and results of measurements on these are given. The final chapter describes the observation of the rotational CO J = 4→3 transition at 461 GHz in the Kleinman Low nebula. From a combination of this measurement with others, lower bounds for the gas kinetic temperature and column density of the shocked gas in this region are derived. (Auth.)

  8. Optomechanical transistor with mechanical gain

    Science.gov (United States)

    Zhang, X. Z.; Tian, Lin; Li, Yong

    2018-04-01

    We study an optomechanical transistor, where an input field can be transferred and amplified unidirectionally in a cyclic three-mode optomechanical system. In this system, the mechanical resonator is coupled simultaneously to two cavity modes. We show that it only requires a finite mechanical gain to achieve the nonreciprocal amplification. Here the nonreciprocity is caused by the phase difference between the linearized optomechanical couplings that breaks the time-reversal symmetry of this system. The amplification arises from the mechanical gain, which provides an effective phonon bath that pumps the mechanical mode coherently. This effect is analogous to the stimulated emission of atoms, where the probe field can be amplified when its frequency is in resonance with that of the anti-Stokes transition. We show that by choosing optimal parameters, this optomechanical transistor can reach perfect unidirectionality accompanied with strong amplification. In addition, the presence of the mechanical gain can result in ultralong delay in the phase of the probe field, which provides an alternative to controlling light transport in optomechanical systems.

  9. High-performance vertical organic transistors.

    Science.gov (United States)

    Kleemann, Hans; Günther, Alrun A; Leo, Karl; Lüssem, Björn

    2013-11-11

    Vertical organic thin-film transistors (VOTFTs) are promising devices to overcome the transconductance and cut-off frequency restrictions of horizontal organic thin-film transistors. The basic physical mechanisms of VOTFT operation, however, are not well understood and VOTFTs often require complex patterning techniques using self-assembly processes which impedes a future large-area production. In this contribution, high-performance vertical organic transistors comprising pentacene for p-type operation and C60 for n-type operation are presented. The static current-voltage behavior as well as the fundamental scaling laws of such transistors are studied, disclosing a remarkable transistor operation with a behavior limited by injection of charge carriers. The transistors are manufactured by photolithography, in contrast to other VOTFT concepts using self-assembled source electrodes. Fluorinated photoresist and solvent compounds allow for photolithographical patterning directly and strongly onto the organic materials, simplifying the fabrication protocol and making VOTFTs a prospective candidate for future high-performance applications of organic transistors. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Colour tuneable light-emitting transistor

    Energy Technology Data Exchange (ETDEWEB)

    Feldmeier, Eva J.; Melzer, Christian; Seggern, Heinz von [Electronic Materials Department, Institute of Materials Science, Technische Universitaet Darmstadt (Germany)

    2010-07-01

    In recent years the interest in ambipolar organic light-emitting field-effect transistors has increased steadily as the devices combine switching behaviour of transistors with light emission. Usually, small molecules and polymers with a band gap in the visible spectral range serve as semiconducting materials. Mandatory remain balanced injection and transport properties for both charge carrier types to provide full control of the spatial position of the recombination zone of electrons and holes in the transistor channel via the applied voltages. As will be presented here, the spatial control of the recombination zone opens new possibilities towards light-emitting devices with colour tuneable emission. In our contribution an organic light-emitting field-effect transistors is presented whose emission colour can be changed by the applied voltages. The organic top-contact field-effect transistor is based on a parallel layer stack of acenes serving as organic transport and emission layers. The transistor displays ambipolar characteristics with a narrow recombination zone within the transistor channel. During operation the recombination zone can be moved by a proper change in the drain and gate bias from one organic semiconductor layer to another one inducing a change in the emission colour. In the presented example the emission maxima can be switched from 530 nm to 580 nm.

  11. Basic matrix algebra and transistor circuits

    CERN Document Server

    Zelinger, G

    1963-01-01

    Basic Matrix Algebra and Transistor Circuits deals with mastering the techniques of matrix algebra for application in transistors. This book attempts to unify fundamental subjects, such as matrix algebra, four-terminal network theory, transistor equivalent circuits, and pertinent design matters. Part I of this book focuses on basic matrix algebra of four-terminal networks, with descriptions of the different systems of matrices. This part also discusses both simple and complex network configurations and their associated transmission. This discussion is followed by the alternative methods of de

  12. Protonic transistors from thin reflecting films

    Energy Technology Data Exchange (ETDEWEB)

    Ordinario, David D.; Phan, Long; Jocson, Jonah-Micah [Department of Chemical Engineering and Materials Science, University of California, Irvine, California 92697 (United States); Nguyen, Tam [Department of Chemistry, University of California, Irvine, California 92697 (United States); Gorodetsky, Alon A., E-mail: alon.gorodetsky@uci.edu [Department of Chemical Engineering and Materials Science, University of California, Irvine, California 92697 (United States); Department of Chemistry, University of California, Irvine, California 92697 (United States)

    2015-01-01

    Ionic transistors from organic and biological materials hold great promise for bioelectronics applications. Thus, much research effort has focused on optimizing the performance of these devices. Herein, we experimentally validate a straightforward strategy for enhancing the high to low current ratios of protein-based protonic transistors. Upon reducing the thickness of the transistors’ active layers, we increase their high to low current ratios 2-fold while leaving the other figures of merit unchanged. The measured ratio of 3.3 is comparable to the best values found for analogous devices. These findings underscore the importance of the active layer geometry for optimum protonic transistor functionality.

  13. Transistors using crystalline silicon devices on glass

    Science.gov (United States)

    McCarthy, Anthony M.

    1995-01-01

    A method for fabricating transistors using single-crystal silicon devices on glass. This method overcomes the potential damage that may be caused to the device during high voltage bonding and employs a metal layer which may be incorporated as part of the transistor. This is accomplished such that when the bonding of the silicon wafer or substrate to the glass substrate is performed, the voltage and current pass through areas where transistors will not be fabricated. After removal of the silicon substrate, further metal may be deposited to form electrical contact or add functionality to the devices. By this method both single and gate-all-around devices may be formed.

  14. Gold nanoparticle-pentacene memory-transistors

    OpenAIRE

    Novembre , Christophe; Guerin , David; Lmimouni , Kamal; Gamrat , Christian; Vuillaume , Dominique

    2008-01-01

    We demonstrate an organic memory-transistor device based on a pentacene-gold nanoparticles active layer. Gold (Au) nanoparticles are immobilized on the gate dielectric (silicon dioxide) of a pentacene transistor by an amino-terminated self-assembled monolayer. Under the application of writing and erasing pulses on the gate, large threshold voltage shift (22 V) and on/off drain current ratio of ~3E4 are obtained. The hole field-effect mobility of the transistor is similar in the on and off sta...

  15. Determination of radial peculiar velocities of galaxy clusters by means of the submillimeter spectrophotometry

    International Nuclear Information System (INIS)

    Sholomitskij, G.B.

    1984-01-01

    The possibility is considered to obtain from the extraatmospheric submillimeter spectrophotometry of galaxy clusters the ratios vsub(r)/Tsub(e) for clusters intergalactic gas that permits, together with the X-ray measurements of electronic temperature Tsub(e) in the case of hot scattering gas to determine absolute radial peculiar velocities vsub(r) of galaxy clusters relative to the relic radiation. By simulating such peculiar velocities as an example for the system of bandpass filters in the wavelength range 300 μm - 2 mm the accuracy of vsub(r) estimates is proved to be about 300 km/s (not taking into account the errors in Tsub(e)) the sensitivity of deeply cooled submillimeter bolometers being 1x10 -15 W/Hzsup(1/2)

  16. The Status of MUSIC: A Multicolor Sub/millimeter MKID Instrument

    Science.gov (United States)

    Schlaerth, J. A.; Czakon, N. G.; Day, P. K.; Downes, T. P.; Duan, R.; Glenn, J.; Golwala, S. R.; Hollister, M. I.; LeDuc, H. G.; Maloney, P. R.; Mazin, B. A.; Nguyen, H. T.; Noroozian, O.; Sayers, J.; Siegel, S.; Zmuidzinas, J.

    2012-05-01

    We report on the recent progress of the Multicolor Submillimeter (kinetic) Inductance Camera, or MUSIC. MUSIC will use antenna-coupled Microwave Kinetic Inductance Detectors to observe in four colors (150 GHz, 230 GHz, 290 GHz and 350 GHz) with 2304 detectors, 576 per band, at the Caltech Submillimeter Observatory. It will deploy in 2012. Here we provide an overview of the instrument, focusing on the array design. We have also used a pathfinder demonstration instrument, DemoCam, to identify problems in advance of the deployment of MUSIC. In particular, we identified two major limiters of our sensitivity: out-of-band light directly coupling to the detectors (i.e. not through the antenna), effectively an excess load, and a large 1/f contribution from our amplifiers and electronics. We discuss the steps taken to mitigate these effects to reach background-limited performance (BLIP) in observation.

  17. Mu-Spec - A High Performance Ultra-Compact Photon Counting spectrometer for Space Submillimeter Astronomy

    Science.gov (United States)

    Moseley, H.; Hsieh, W.-T.; Stevenson, T.; Wollack, E.; Brown, A.; Benford, D.; Sadleir; U-Yen, I.; Ehsan, N.; Zmuidzinas, J.; hide

    2011-01-01

    We have designed and are testing elements of a fully integrated submillimeter spectrometer based on superconducting microstrip technology. The instrument can offer resolving power R approximately 1500, and its high frequency cutoff is set by the gap of available high performance superconductors. All functions of the spectrometer are integrated - light is coupled to the microstrip circuit with a planar antenna, the spectra discrimination is achieved using a synthetic grating, orders are separated using planar filter, and detected using photon counting MKID detector. This spectrometer promises to revolutionize submillimeter spectroscopy from space. It replaces instruments with the scale of 1m with a spectrometer on a 10 cm Si wafer. The reduction in mass and volume promises a much higher performance system within available resource in a space mission. We will describe the system and the performance of the components that have been fabricated and tested.

  18. GaN transistors on Si for switching and high-frequency applications

    Science.gov (United States)

    Ueda, Tetsuzo; Ishida, Masahiro; Tanaka, Tsuyoshi; Ueda, Daisuke

    2014-10-01

    In this paper, recent advances of GaN transistors on Si for switching and high-frequency applications are reviewed. Novel epitaxial structures including superlattice interlayers grown by metal organic chemical vapor deposition (MOCVD) relieve the strain and eliminate the cracks in the GaN over large-diameter Si substrates up to 8 in. As a new device structure for high-power switching application, Gate Injection Transistors (GITs) with a p-AlGaN gate over an AlGaN/GaN heterostructure successfully achieve normally-off operations maintaining high drain currents and low on-state resistances. Note that the GITs on Si are free from current collapse up to 600 V, by which the drain current would be markedly reduced after the application of high drain voltages. Highly efficient operations of an inverter and DC-DC converters are presented as promising applications of GITs for power switching. The high efficiencies in an inverter, a resonant LLC converter, and a point-of-load (POL) converter demonstrate the superior potential of the GaN transistors on Si. As for high-frequency transistors, AlGaN/GaN heterojuction field-effect transistors (HFETs) on Si designed specifically for microwave and millimeter-wave frequencies demonstrate a sufficiently high output power at these frequencies. Output powers of 203 W at 2.5 GHz and 10.7 W at 26.5 GHz are achieved by the fabricated GaN transistors. These devices for switching and high-frequency applications are very promising as future energy-efficient electronics because of their inherent low fabrication cost and superior device performance.

  19. Generation of a strong core-centering force in a submillimeter compound droplet system

    International Nuclear Information System (INIS)

    Lee, M.C.; Feng, I.; Elleman, D.D.; Wang, T.G.; Young, A.T.

    1981-01-01

    By amplitude-modulating the driving voltage of an acoustic levitating apparatus, a strong core-centering force can be generated in a submillimeter compound droplet system suspended by the radiation pressure in a gaseous medium. Depending on the acoustic characteristics of the droplet system, it has been found that the technique can be utilized advantageously in the multiple-layer coating of an inertial-confinement-fusion pellet

  20. Development of a submillimeter free electron laser using a compact electro-static accelerator

    International Nuclear Information System (INIS)

    Kawamura, Y.; Shu, S.H.; Tanabe, T.; Li, D.J.; Toyoda, K.

    1995-01-01

    An experimental facilities for the studies on submillimeter wavelength free electron laser (FEL) are now under construction in our group. In this paper the possibilities for the two kinds of operation modes, which are expected to be obtained, such as the self mode-locked operations in a small net-gain region and the evolution of CW radiation in a large net-gain region, are analized. (author)

  1. DUST PROPERTIES OF LOCAL DUST-OBSCURED GALAXIES WITH THE SUBMILLIMETER ARRAY

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Ho Seong; Andrews, Sean M.; Geller, Margaret J., E-mail: hhwang@cfa.harvard.edu, E-mail: sandrews@cfa.harvard.edu, E-mail: mgeller@cfa.harvard.edu [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)

    2013-11-01

    We report Submillimeter Array observations of the 880 μm dust continuum emission for four dust-obscured galaxies (DOGs) in the local universe. Two DOGs are clearly detected with S{sub ν}(880 μm) =10-13 mJy and S/N > 5, but the other two are not detected with 3σ upper limits of S{sub ν}(880 μm) =5-9 mJy. Including an additional two local DOGs with submillimeter data from the literature, we determine the dust masses and temperatures for six local DOGs. The infrared luminosities and dust masses for these DOGs are in the ranges of 1.2-4.9 × 10{sup 11}(L{sub ☉}) and 4-14 × 10{sup 7}(M{sub ☉}), respectively. The dust temperatures derived from a two-component modified blackbody function are 23-26 K and 60-124 K for the cold and warm dust components, respectively. Comparison of local DOGs with other infrared luminous galaxies with submillimeter detections shows that the dust temperatures and masses do not differ significantly among these objects. Thus, as argued previously, local DOGs are not a distinctive population among dusty galaxies, but simply represent the high-end tail of the dust obscuration distribution.

  2. DUST PROPERTIES OF LOCAL DUST-OBSCURED GALAXIES WITH THE SUBMILLIMETER ARRAY

    International Nuclear Information System (INIS)

    Hwang, Ho Seong; Andrews, Sean M.; Geller, Margaret J.

    2013-01-01

    We report Submillimeter Array observations of the 880 μm dust continuum emission for four dust-obscured galaxies (DOGs) in the local universe. Two DOGs are clearly detected with S ν (880 μm) =10-13 mJy and S/N > 5, but the other two are not detected with 3σ upper limits of S ν (880 μm) =5-9 mJy. Including an additional two local DOGs with submillimeter data from the literature, we determine the dust masses and temperatures for six local DOGs. The infrared luminosities and dust masses for these DOGs are in the ranges of 1.2-4.9 × 10 11 (L ☉ ) and 4-14 × 10 7 (M ☉ ), respectively. The dust temperatures derived from a two-component modified blackbody function are 23-26 K and 60-124 K for the cold and warm dust components, respectively. Comparison of local DOGs with other infrared luminous galaxies with submillimeter detections shows that the dust temperatures and masses do not differ significantly among these objects. Thus, as argued previously, local DOGs are not a distinctive population among dusty galaxies, but simply represent the high-end tail of the dust obscuration distribution

  3. Liquid crystals for organic transistors (Conference Presentation)

    Science.gov (United States)

    Hanna, Jun-ichi; Iino, Hiroaki

    2016-09-01

    Liquid crystals are a new type of organic semiconductors exhibiting molecular orientation in self-organizing manner, and have high potential for device applications. In fact, various device applications have been proposed so far, including photosensors, solar cells, light emitting diodes, field effect transistors, and so on.. However, device performance in those fabricated with liquid crystals is less than those of devices fabricated with conventional materials in spite of unique features of liquid crystals. Here we discuss how we can utilize the liquid crystallinity in organic transistors and how we can overcome conventional non-liquid crystalline organic transistor materials. Then, we demonstrate high performance organic transistors fabricated with a smectic E liquid crystal of Ph-BTBT-10, which show high mobility of over 10cm2/Vs and high thermal durability of over 200oC in OFETs fabricated with its spin-coated polycrystalline thin films.

  4. Lateral power transistors in integrated circuits

    CERN Document Server

    Erlbacher, Tobias

    2014-01-01

    This book details and compares recent advancements in the development of novel lateral power transistors (LDMOS devices) for integrated circuits in power electronic applications. It includes the state-of-the-art concept of double-acting RESURF topologies.

  5. Water-gel for gating graphene transistors.

    Science.gov (United States)

    Kim, Beom Joon; Um, Soong Ho; Song, Woo Chul; Kim, Yong Ho; Kang, Moon Sung; Cho, Jeong Ho

    2014-05-14

    Water, the primary electrolyte in biology, attracts significant interest as an electrolyte-type dielectric material for transistors compatible with biological systems. Unfortunately, the fluidic nature and low ionic conductivity of water prevents its practical usage in such applications. Here, we describe the development of a solid state, megahertz-operating, water-based gate dielectric system for operating graphene transistors. The new electrolyte systems were prepared by dissolving metal-substituted DNA polyelectrolytes into water. The addition of these biocompatible polyelectrolytes induced hydrogelation to provide solid-state integrity to the system. They also enhanced the ionic conductivities of the electrolytes, which in turn led to the quick formation of an electric double layer at the graphene/electrolyte interface that is beneficial for modulating currents in graphene transistors at high frequencies. At the optimized conditions, the Na-DNA water-gel-gated flexible transistors and inverters were operated at frequencies above 1 MHz and 100 kHz, respectively.

  6. Potential of carbon nanotube field effect transistors for analogue circuits

    KAUST Repository

    Hayat, Khizar

    2013-05-11

    This Letter presents a detailed comparison of carbon nanotube field effect transistors (CNFETs) and metal oxide semiconductor field effect transistors (MOSFETs) with special focus on carbon nanotube FET\\'s potential for implementing analogue circuits in the mm-wave and sub-terahertz range. The latest CNFET lithographic dimensions place it at-par with complementary metal oxide semiconductor in terms of current handling capability, whereas the forecasted improvement in the lithography enables the CNFETs to handle more than twice the current of MOSFETs. The comparison of RF parameters shows superior performance of CNFETs with a g m , f T and f max of 2.7, 2.6 and 4.5 times higher, respectively. MOSFET- and CNFET-based inverter, three-stage ring oscillator and LC oscillator have been designed and compared as well. The CNFET-based inverters are found to be ten times faster, the ring oscillator demonstrates three times higher oscillation frequency and CNFET-based LC oscillator also shows improved performance than its MOSFET counterpart.

  7. Potential of carbon nanotube field effect transistors for analogue circuits

    KAUST Repository

    Hayat, Khizar; Cheema, Hammad; Shamim, Atif

    2013-01-01

    This Letter presents a detailed comparison of carbon nanotube field effect transistors (CNFETs) and metal oxide semiconductor field effect transistors (MOSFETs) with special focus on carbon nanotube FET's potential for implementing analogue circuits in the mm-wave and sub-terahertz range. The latest CNFET lithographic dimensions place it at-par with complementary metal oxide semiconductor in terms of current handling capability, whereas the forecasted improvement in the lithography enables the CNFETs to handle more than twice the current of MOSFETs. The comparison of RF parameters shows superior performance of CNFETs with a g m , f T and f max of 2.7, 2.6 and 4.5 times higher, respectively. MOSFET- and CNFET-based inverter, three-stage ring oscillator and LC oscillator have been designed and compared as well. The CNFET-based inverters are found to be ten times faster, the ring oscillator demonstrates three times higher oscillation frequency and CNFET-based LC oscillator also shows improved performance than its MOSFET counterpart.

  8. Transfer-free fabrication of graphene transistors

    OpenAIRE

    Wessely, P.J.; Wessely, F.; Birinci, E.; Schwalke, U.; Riedinger, B.

    2012-01-01

    The authors invented a method to fabricate graphene transistors on oxidized silicon wafers without the need to transfer graphene layers. To stimulate the growth of graphene layers on oxidized silicon, a catalyst system of nanometer thin aluminum/nickel double layer is used. This catalyst system is structured via liftoff before the wafer enters the catalytic chemical vapor deposition (CCVD) chamber. In the subsequent methane-based growth process, monolayer graphene field-effect transistors and...

  9. Diffusion pipes at PNP switching transistors

    International Nuclear Information System (INIS)

    Sachelarie, D.; Postolache, C.; Gaiseanu, F.

    1976-01-01

    The appearance of the ''diffusion pipes'' greatly affects the fabrication of the PNP high-frequency/very-fast-switching transistors. A brief review of the principal problems connected to the presence of these ''pipes'' is made. A research program is presented which permitted the fabrication of the PNP switching transistors at ICCE-Bucharest, with transition frequency fsub(T) = 1.2 GHz and storage time tsub(s) = 4.5 ns. (author)

  10. Integrated amplifying circuit with MOS transistors

    Energy Technology Data Exchange (ETDEWEB)

    Baylac, B; Merckel, G; Meunier, P

    1974-01-25

    The invention relates to a feedback-pass-band amplifier with MOS-transistors. The differential stage of conventional amplifiers is changed into an adding state, whereas the differential amplification stages are changed into amplifier inverter stages. All MOS transistors used in that amplifier are of similar configuration and are interdigitized, whereby the operating speed dispersion is reduced. This can be applied to obtaining a measurement channel for proportional chambers.

  11. The Submillimeter Array – current status and future plans

    Science.gov (United States)

    Blundell, Raymond

    2018-01-01

    The current SMA receiver systems were designed in the mid-1990s and have been operating for more than fifteen years. With regular upgrades to receivers, deployment of the SWARM correlator, expansion of the IF signal transport bandwidth via improvements to the analog IF signal processing hardware, and many other enhancements, the SMA currently greatly outperforms its original specifications in terms of sensitivity, instantaneous bandwidth, and availability of observing modes such as full-Stokes polarization and dual frequency operation.We have recently started to implement a three-year instrument upgrade plan, which we are calling the wSMA. The wSMA will offer even wider bandwidth operation than the current SMA and improved sensitivity. The major subsystems that will form the wSMA include significantly improved, dual polarization receiver cartridges housed in a new cryostat; local oscillator units incorporating modern mm-wave technology; an upgraded signal transmission system; and a further expansion of the SWARM correlator. The cryostat will be cooled by a low-maintenance pulse-tube cryocooler. Two dual-polarization receiver cartridges will cover approximately the same sky frequencies as the current receiver sets; the low-band receiver will be fed by an LO unit covering 210-270 GHz, and the high-band receiver will be fed by an LO covering 280-360 GHz. With a receiver IF band of 4-20 GHz, this will enable continuous sky frequency coverage from 190 GHz to 380 GHz.Details of the upgrade plans will be presented together with a discussion of scientific opportunities afforded by this upgrade, which, once implemented, will enable the SMA to continue to produce the highest quality science throughout the next decade.

  12. Nonstationary behavior in a delayed feedback traveling wave tube folded waveguide oscillator

    International Nuclear Information System (INIS)

    Ryskin, N.M.; Titov, V.N.; Han, S.T.; So, J.K.; Jang, K.H.; Kang, Y.B.; Park, G.S.

    2004-01-01

    Folded waveguide traveling-wave tubes (FW TWT) are among the most promising candidates for powerful compact amplifiers and oscillators in millimeter and submillimeter wave bands. In this paper, the nonstationary behavior of a FW TWT oscillator with delayed feedback is investigated. Starting conditions of the oscillations are derived analytically. Results of numerical simulation of single-frequency, self-modulation (multifrequency) and chaotic generation regimes are presented. Mode competition phenomena, multistability and hysteresis are discussed

  13. QUEST FOR COSMOS SUBMILLIMETER GALAXY COUNTERPARTS USING CARMA AND VLA: IDENTIFYING THREE HIGH-REDSHIFT STARBURST GALAXIES

    International Nuclear Information System (INIS)

    Smolčić, V.; Navarrete, F.; Bertoldi, F.; Aravena, M.; Sheth, K.; Ilbert, O.; Yun, M. S.; Salvato, M.; Finoguenov, A.; McCracken, H. J.; Diener, C.; Aretxaga, I.; Hughes, D.; Wilson, G.; Riechers, D. A.; Capak, P.; Scoville, N. Z.; Karim, A.; Schinnerer, E.

    2012-01-01

    We report on interferometric observations at 1.3 mm at 2''-3'' resolution using the Combined Array for Research in Millimeter-wave Astronomy. We identify multi-wavelength counterparts of three submillimeter galaxies (SMGs; F 1m > 5.5 mJy) in the COSMOS field, initially detected with MAMBO and AzTEC bolometers at low, ∼10''-30'', resolution. All three sources—AzTEC/C1, Cosbo-3, and Cosbo-8—are identified to coincide with positions of 20 cm radio sources. Cosbo-3, however, is not associated with the most likely radio counterpart, closest to the MAMBO source position, but with that farther away from it. This illustrates the need for intermediate-resolution (∼2'') mm-observations to identify the correct counterparts of single-dish-detected SMGs. All of our three sources become prominent only at NIR wavelengths, and their mm-to-radio flux based redshifts suggest that they lie at redshifts z ∼> 2. As a proof of concept, we show that photometric redshifts can be well determined for SMGs, and we find photometric redshifts of 5.6 ± 1.2, 1.9 +0.9 –0.5 , and ∼4 for AzTEC/C1, Cosbo-3, and Cosbo-8, respectively. Using these we infer that these galaxies have radio-based star formation rates of ∼> 1000 M ☉ yr –1 and IR luminosities of ∼10 13 L ☉ consistent with properties of high-redshift SMGs. In summary, our sources reflect a variety of SMG properties in terms of redshift and clustering, consistent with the framework that SMGs are progenitors of z ∼ 2 and today's passive galaxies.

  14. The Possible Submillimeter Bump and Accretion-jet in the Central Supermassive Black Hole of NGC 4993

    Science.gov (United States)

    Wu, Qingwen; Feng, Jianchao; Fan, Xuliang

    2018-03-01

    NGC 4993, as a host galaxy of the electromagnetic counterpart of the first gravitational-wave detection of a binary neutron-star merger, was observed by many powerful telescopes from radio to γ-ray wavebands. The weak nuclear activities of NGC 4993 suggest that it is a low-luminosity active galactic nuclei (LLAGNs). We build the multiwaveband spectral energy distributions (SEDs) of NGC 4993 from the literature. We find that the radio spectrum at ∼100–300 GHz is much steeper than that of the low-frequency waveband (e.g., 6–100 GHz), where this break was also found in the supermassive black holes (SMBHs) in our galaxy center (Sgr A*), and in some other nearby AGNs. The radio emission above and below this break may have different physical origins, which provide an opportunity to probe the accretion and jet properties. We model the multiwaveband SEDs of NGC 4993 with an advection-dominated accretion flow (ADAF) jet model. We find that the high-frequency steep radio emission at the millimeter waveband is consistent with the prediction of the ADAF, while the low-frequency flat radio spectrum is better fitted by the jet. Furthermore, the X-ray emission can also be simultaneously explained by the ADAF model. From the model fits, we estimate important parameters of the central engine (e.g., the accretion rate near the horizon of the black hole and the mass-loss rate in the jet) for NGC 4993. This result strengthens the theory that the millimeter, submillimeter, and deep X-ray observations are crucial to understanding the weak or quiescent activities in SMBH systems. Further simultaneous millimeter and X-ray monitoring of this kind of LLAGN will help us to better understand the physical origin of multiwaveband emission.

  15. Failure rates for accelerated acceptance testing of silicon transistors

    Science.gov (United States)

    Toye, C. R.

    1968-01-01

    Extrapolation tables for the control of silicon transistor product reliability have been compiled. The tables are based on a version of the Arrhenius statistical relation and are intended to be used for low- and medium-power silicon transistors.

  16. Organic tunnel field effect transistors

    KAUST Repository

    Tietze, Max Lutz

    2017-06-29

    Various examples are provided for organic tunnel field effect transistors (OTFET), and methods thereof. In one example, an OTFET includes a first intrinsic layer (i-layer) of organic semiconductor material disposed over a gate insulating layer; source (or drain) contact stacks disposed on portions of the first i-layer; a second i-layer of organic semiconductor material disposed on the first i-layer surrounding the source (or drain) contact stacks; an n-doped organic semiconductor layer disposed on the second i-layer; and a drain (or source) contact layer disposed on the n-doped organic semiconductor layer. The source (or drain) contact stacks can include a p-doped injection layer, a source (or drain) contact layer, and a contact insulating layer. In another example, a method includes disposing a first i-layer over a gate insulating layer; forming source or drain contact stacks; and disposing a second i-layer, an n-doped organic semiconductor layer, and a drain or source contact.

  17. Ambipolar phosphorene field effect transistor.

    Science.gov (United States)

    Das, Saptarshi; Demarteau, Marcel; Roelofs, Andreas

    2014-11-25

    In this article, we demonstrate enhanced electron and hole transport in few-layer phosphorene field effect transistors (FETs) using titanium as the source/drain contact electrode and 20 nm SiO2 as the back gate dielectric. The field effect mobility values were extracted to be ∼38 cm(2)/Vs for electrons and ∼172 cm(2)/Vs for the holes. On the basis of our experimental data, we also comprehensively discuss how the contact resistances arising due to the Schottky barriers at the source and the drain end effect the different regime of the device characteristics and ultimately limit the ON state performance. We also propose and implement a novel technique for extracting the transport gap as well as the Schottky barrier height at the metal-phosphorene contact interface from the ambipolar transfer characteristics of the phosphorene FETs. This robust technique is applicable to any ultrathin body semiconductor which demonstrates symmetric ambipolar conduction. Finally, we demonstrate a high gain, high noise margin, chemical doping free, and fully complementary logic inverter based on ambipolar phosphorene FETs.

  18. Low-background transistors for application in nuclear electronics

    International Nuclear Information System (INIS)

    Krasnokutskij, R.N.; Kurchaninov, L.L.; Fedyakin, N.N.; Shuvalov, R.S.

    1988-01-01

    Investigations of silicon transistors were carried out to determine transistors with low value of base distributed resistance (R). Measurement results for R and current amplification coefficient β are presented for bipolar transistor several types. Correlations between R and β were studied. KT 399A, 2T640A and KT3117B transistors are found to be most adequate ones as a base for low-background amplifier development

  19. High Accuracy Transistor Compact Model Calibrations

    Energy Technology Data Exchange (ETDEWEB)

    Hembree, Charles E. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Mar, Alan [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Robertson, Perry J. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    Typically, transistors are modeled by the application of calibrated nominal and range models. These models consists of differing parameter values that describe the location and the upper and lower limits of a distribution of some transistor characteristic such as current capacity. Correspond- ingly, when using this approach, high degrees of accuracy of the transistor models are not expected since the set of models is a surrogate for a statistical description of the devices. The use of these types of models describes expected performances considering the extremes of process or transistor deviations. In contrast, circuits that have very stringent accuracy requirements require modeling techniques with higher accuracy. Since these accurate models have low error in transistor descriptions, these models can be used to describe part to part variations as well as an accurate description of a single circuit instance. Thus, models that meet these stipulations also enable the calculation of quantifi- cation of margins with respect to a functional threshold and uncertainties in these margins. Given this need, new model high accuracy calibration techniques for bipolar junction transis- tors have been developed and are described in this report.

  20. EXCITATION CONDITIONS IN THE MULTI-COMPONENT SUBMILLIMETER GALAXY SMM J00266+1708

    International Nuclear Information System (INIS)

    Sharon, Chelsea E.; Baker, Andrew J.; Harris, Andrew I.; Tacconi, Linda J.; Lutz, Dieter; Longmore, Steven N.

    2015-01-01

    We present multiline CO observations of the complex submillimeter galaxy SMM J00266+1708. Using the Zpectrometer on the Green Bank Telescope, we provide the first precise spectroscopic measurement of its redshift (z = 2.742). Based on followup CO(1-0), CO(3-2), and CO(5-4) mapping, SMM J00266+1708 appears to have two distinct components separated by ∼500 km s –1 that are nearly coincident along our line of sight. The two components show hints of different kinematics, with the blueshifted component dispersion-dominated and the redshifted component showing a clear velocity gradient. CO line ratios differ slightly between the two components, indicating that the physical conditions in their molecular gas may not be alike. We tentatively infer that SMM J00266+1708 is an ongoing merger with a mass ratio of (7.8 ± 4.0)/sin 2 (i), with its overall size and surface brightness closely resembling that of other merging systems. We perform large velocity gradient modeling of the CO emission from both components and find that each component's properties are consistent with a single phase of molecular gas (i.e., a single temperatures and density); additional multi-phase modeling of the redshifted component, although motivated by a CO(1-0) size larger than the CO(3-2) size, is inconclusive. SMM J00266+1708 provides evidence of early stage mergers within the submillimeter galaxy population. Continuum observations of J00266 at the ∼1'' resolution of our observations could not have distinguished between the two components due to their separation (0.''73 ± 0.''06), illustrating that the additional velocity information provided by spectral line studies is important for addressing the prevalence of unresolved galaxy pairs in low-resolution submillimeter surveys

  1. SUBMILLIMETER H{sub 2}O MEGAMASERS IN NGC 4945 AND THE CIRCINUS GALAXY

    Energy Technology Data Exchange (ETDEWEB)

    Pesce, D. W. [Department of Astronomy, University of Virginia, 530 McCormick Road, Charlottesville, VA 22904 (United States); Braatz, J. A.; Impellizzeri, C. M. V., E-mail: dpesce@virginia.edu [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States)

    2016-08-10

    We present 321 GHz observations of five active galactic nuclei (AGNs) from ALMA Cycle 0 archival data: NGC 5793, NGC 1068, NGC 1386, NGC 4945, and the Circinus galaxy. Submillimeter maser emission is detected for the first time toward NGC 4945, and we present a new analysis of the submillimeter maser system in Circinus. None of the other three galaxies show maser emission, although we have detected and imaged the continuum from every galaxy. Both NGC 4945 and Circinus are known to host strong (≳10 Jy) 22 GHz megamaser emission, and VLBI observations have shown that the masers reside in the innermost ∼1 pc of the galaxies. The peak flux densities of the 321 GHz masers in both systems are substantially weaker (by a factor of ∼100) than what is observed at 22 GHz, although the corresponding isotropic luminosities are more closely matched (within a factor of ∼10) between the two transitions. We compare the submillimeter spectra presented here to the known 22 GHz spectra in both galaxies, and we argue that while both transitions originate from the gaseous environment near the AGNs, not all sites are in common. In Circinus, the spectral structure of the 321 GHz masers indicates that they may trace the accretion disk at radii interior to the 22 GHz masers. The continuum emission in NGC 4945 and NGC 5793 shows a spatial distribution indicative of an origin in the galactic disks (likely thermal dust emission), while for the other three galaxies the emission is centrally concentrated and likely originates from the nucleus.

  2. SUBMILLIMETER-HCN DIAGRAM FOR ENERGY DIAGNOSTICS IN THE CENTERS OF GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Izumi, Takuma; Kohno, Kotaro [Institute of Astronomy, School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Aalto, Susanne [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Observatory, SE-439 94 Onsala (Sweden); Espada, Daniel; Martín, Sergio; Nakanishi, Kouichiro [Joint ALMA Observatory, Alonso de Córdova, 3107, Vitacura, Santiago 763-0355 (Chile); Fathi, Kambiz [Stockholm Observatory, Department of Astronomy, Stockholm University, AlbaNova Centre, SE-106 91 Stockholm (Sweden); Harada, Nanase; Hsieh, Pei-Ying; Matsushita, Satoki [Academia Sinica, Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China); Hatsukade, Bunyo; Imanishi, Masatoshi [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Krips, Melanie [Institut de Radio Astronomie Millimétrique, 300 rue de la Piscine, Domaine Universitaire, F-38406 St. Martin d’Hères (France); Meier, David S. [Department of Physics, New Mexico Institute of Mining and Technology, 801 Leroy Place, Soccoro, NM 87801 (United States); Nakai, Naomasa [Department of Physics, Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Ten-nodai, Tsukuba, Ibaraki 305-8571 (Japan); Schinnerer, Eva [Max Planck Institute for Astronomy, Königstuhl 17, Heidelberg D-69117 (Germany); Sheth, Kartik [NASA, 300 E Street SW, Washington, DC 20546 (United States); Terashima, Yuichi [Department of Physics, Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime 790-8577 (Japan); Turner, Jean L., E-mail: takumaizumi@ioa.s.u-tokyo.ac.jp [Department of Physics and Astronomy, UCLA, 430 Portola Plaza, Los Angeles, CA 90095-1547 (United States)

    2016-02-10

    Compiling data from literature and the Atacama Large Millimeter/submillimeter Array archive, we show enhanced HCN(4–3)/HCO{sup +}(4–3) and/or HCN(4–3)/CS(7–6) integrated intensity ratios in circumnuclear molecular gas around active galactic nuclei (AGNs) compared to those in starburst (SB) galaxies (submillimeter HCN enhancement). The number of sample galaxies is significantly increased from our previous work. We expect that this feature could potentially be an extinction-free energy diagnostic tool of nuclear regions of galaxies. Non-LTE radiative transfer modelings of the above molecular emission lines involving both collisional and radiative excitation, as well as a photon trapping effect, were conducted to investigate the cause of the high line ratios in AGNs. As a result, we found that enhanced abundance ratios of HCN to HCO{sup +} and HCN to CS in AGNs as compared to SB galaxies by a factor of a few to even ≳10 are a plausible explanation for the submillimeter HCN enhancement. However, a counterargument of a systematically higher gas density in AGNs than in SB galaxies can also be a plausible scenario. Although we cannot fully distinguish these two scenarios at this moment owing to an insufficient amount of multi-transition, multi-species data, the former scenario is indicative of abnormal chemical composition in AGNs. Regarding the actual mechanism to realize the composition, we suggest that it is difficult with conventional gas-phase X-ray-dominated region ionization models to reproduce the observed high line ratios. We might have to take into account other mechanisms such as neutral–neutral reactions that are efficiently activated in high-temperature environments and/or mechanically heated regions to further understand the high line ratios in AGNs.

  3. EXCITATION CONDITIONS IN THE MULTI-COMPONENT SUBMILLIMETER GALAXY SMM J00266+1708

    Energy Technology Data Exchange (ETDEWEB)

    Sharon, Chelsea E.; Baker, Andrew J. [Department of Physics and Astronomy, Rutgers, the State University of New Jersey, Piscataway, NJ 08854-8019 (United States); Harris, Andrew I. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Tacconi, Linda J.; Lutz, Dieter [Max-Planck-Institut für extraterrestrische Physik (MPE), Giessenbachstr. 1, D-85748 Garching (Germany); Longmore, Steven N. [Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Warf, Birkenhead CH41 1LD (United Kingdom)

    2015-01-10

    We present multiline CO observations of the complex submillimeter galaxy SMM J00266+1708. Using the Zpectrometer on the Green Bank Telescope, we provide the first precise spectroscopic measurement of its redshift (z = 2.742). Based on followup CO(1-0), CO(3-2), and CO(5-4) mapping, SMM J00266+1708 appears to have two distinct components separated by ∼500 km s{sup –1} that are nearly coincident along our line of sight. The two components show hints of different kinematics, with the blueshifted component dispersion-dominated and the redshifted component showing a clear velocity gradient. CO line ratios differ slightly between the two components, indicating that the physical conditions in their molecular gas may not be alike. We tentatively infer that SMM J00266+1708 is an ongoing merger with a mass ratio of (7.8 ± 4.0)/sin {sup 2}(i), with its overall size and surface brightness closely resembling that of other merging systems. We perform large velocity gradient modeling of the CO emission from both components and find that each component's properties are consistent with a single phase of molecular gas (i.e., a single temperatures and density); additional multi-phase modeling of the redshifted component, although motivated by a CO(1-0) size larger than the CO(3-2) size, is inconclusive. SMM J00266+1708 provides evidence of early stage mergers within the submillimeter galaxy population. Continuum observations of J00266 at the ∼1'' resolution of our observations could not have distinguished between the two components due to their separation (0.''73 ± 0.''06), illustrating that the additional velocity information provided by spectral line studies is important for addressing the prevalence of unresolved galaxy pairs in low-resolution submillimeter surveys.

  4. Status of a Novel 4-Band Submm/mm Camera for the Caltech Submillimeter Observatory

    Science.gov (United States)

    Noroozian, Omid; Day, P.; Glenn, J.; Golwala, S.; Kumar, S.; LeDuc, H. G.; Mazin, B.; Nguyen, H. T.; Schlaerth, J.; Vaillancourt, J. E.; Vayonakis, A.; Zmuidzinas, J.

    2007-12-01

    Submillimeter observations are important to the understanding of galaxy formation and evolution. Determination of the spectral energy distribution in the millimeter and submillimeter regimes allows important and powerful diagnostics. To this end, we are undertaking the construction of a 4-band (750, 850, 1100, 1300 microns) 8-arcminute field of view camera for the Caltech Submillimeter Observatory. The focal plane will make use of three novel technologies: photolithographic phased array antennae, on-chip band-pass filters, and microwave kinetic inductance detectors (MKID). The phased array antenna design obviates beam-defining feed horns. On-chip band-pass filters eliminate band-defining metal-mesh filters. Together, the antennae and filters enable each spatial pixel to observe in all four bands simultaneously. MKIDs are highly multiplexable background-limited photon detectors. Readout of the MKID array will be done with software-defined radio (See poster by Max-Moerbeck et al.). This camera will provide an order-of-magnitude larger mapping speed than existing instruments and will be comparable to SCUBA 2 in terms of the detection rate for dusty sources, but complementary to SCUBA 2 in terms of wavelength coverage. We present results from an engineering run with a demonstration array, the baseline design for the science array, and the status of instrument design, construction, and testing. We anticipate the camera will be available at the CSO in 2010. This work has been supported by NASA ROSES APRA grants NNG06GG16G and NNG06GC71G, the NASA JPL Research and Technology Development Program, and the Gordon and Betty Moore Foundation.

  5. Measurement Results of the Caltech Submillimeter Observatory 230 GHz and 460 GHz Balanced Receivers

    Science.gov (United States)

    Kooi, J. W.; Monje, R. R.; Force, B. L.; Rice, F.; Miller, D.; Phillips, T. G.

    2010-03-01

    The Caltech Submillimeter observatory (CSO) is located on top of Mauna Kea, Hawaii, at an altitude of 4.2km. The existing suite of heterodyne receivers covering the submillimeter band is rapidly aging, and in need of replacement. To this extend we have developed a family of balanced receivers covering the astrophysical important 180-720 GHz atmospheric windows. For the CSO, wide IF bandwidth receivers are implemented in a balanced receiver configuration with dual frequency observation capability. This arrangement was opted to be an optimal compromise between scientific merit and finite funding. In principle, the balanced receiver configuration has the advantage that common mode amplitude noise in the LO system is canceled, while at the same time utilizing all available LO power. Both of these features facilitate the use of commercially available synthesized LO system. In combination with a 4 GHz IF bandwidth, the described receiver layout allows for rapid high resolution spectral line surveys. Dual frequency observation is another important mode of operation offered by the new facility instrumentation. Two band observations are accomplished by separating the H and V polarizations of the incoming signal and routing them via folded optics to the appropriate polarization sensitive balanced mixer. Scientifically this observation mode facilitates pointing for the higher receiver band under mediocre weather conditions and a doubling of scientific throughput (2 x 4 GHz) under good weather conditions. Not only do these changes greatly enhance the spectroscopic capabilities of the CSO, they also enable the observatory to be integrated into the Harvard-Smithsonian Submillimeter Array (eSMA) as an additional baseline. The upgrade of the 345 GHz/650 GHz dual band balanced receivers is not far behind. All the needed hardware has been procured, and commissioning is expected the summer of 2010. The SIS junctions are capable of a 2-12 GHz bandwidth.

  6. Design method for a digitally trimmable MOS transistor structure

    DEFF Research Database (Denmark)

    Ning, Feng; Bruun, Erik

    1996-01-01

    A digitally trimmable MOS transistor is a MOS transistor consisting of a drain, a source, and a main gate as well as several subgates. The transconductance of the transistor is tunabledigitally by means of connecting subgates either to the main gate or to the source terminal. In this paper, a sys...

  7. Stretchable transistors with buckled carbon nanotube films as conducting channels

    Science.gov (United States)

    Arnold, Michael S; Xu, Feng

    2015-03-24

    Thin-film transistors comprising buckled films comprising carbon nanotubes as the conductive channel are provided. Also provided are methods of fabricating the transistors. The transistors, which are highly stretchable and bendable, exhibit stable performance even when operated under high tensile strains.

  8. High mobility polymer gated organic field effect transistor using zinc ...

    Indian Academy of Sciences (India)

    Organic thin film transistors were fabricated using evaporated zinc phthalocyanine as the active layer. Parylene film ... At room temperature, these transistors exhibit p-type conductivity with field-effect ... Keywords. Organic semiconductor; field effect transistor; phthalocyanine; high mobility. ... The evaporation rate was kept at ...

  9. EMPIRICAL PREDICTIONS FOR (SUB-)MILLIMETER LINE AND CONTINUUM DEEP FIELDS

    Energy Technology Data Exchange (ETDEWEB)

    Da Cunha, Elisabete; Walter, Fabian; Decarli, Roberto; Rix, Hans-Walter [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Bertoldi, Frank [Argelander Institute for Astronomy, University of Bonn, Auf dem Huegel 71, D-53121 Bonn (Germany); Carilli, Chris [National Radio Astronomy Observatory, Pete V. Domenici Array Science Center, P.O. Box O, Socorro, NM 87801 (United States); Daddi, Emanuele; Elbaz, David; Sargent, Mark [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, Irfu/Service d' Astrophysique, CEA Saclay, Orme des Merisiers, F-91191 Gif-sur-Yvette Cedex (France); Ivison, Rob [UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Maiolino, Roberto [Cavendish Laboratory, University of Cambridge, 19 J.J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Riechers, Dominik [Astronomy Department, California Institute of Technology, MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Smail, Ian [Institute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE (United Kingdom); Weiss, Axel, E-mail: cunha@mpia.de [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany)

    2013-03-01

    Modern (sub-)millimeter/radio interferometers such as ALMA, JVLA, and the PdBI successor NOEMA will enable us to measure the dust and molecular gas emission from galaxies that have luminosities lower than the Milky Way, out to high redshifts and with unprecedented spatial resolution and sensitivity. This will provide new constraints on the star formation properties and gas reservoir in galaxies throughout cosmic times through dedicated deep field campaigns targeting the CO/[C II] lines and dust continuum emission in the (sub-)millimeter regime. In this paper, we present empirical predictions for such line and continuum deep fields. We base these predictions on the deepest available optical/near-infrared Advanced Camera for Surveys and NICMOS data on the Hubble Ultra Deep Field (over an area of about 12 arcmin{sup 2}). Using a physically motivated spectral energy distribution model, we fit the observed optical/near-infrared emission of 13,099 galaxies with redshifts up to z = 5, and obtain median-likelihood estimates of their stellar mass, star formation rate, dust attenuation, and dust luminosity. We combine the attenuated stellar spectra with a library of infrared emission models spanning a wide range of dust temperatures to derive statistical constraints on the dust emission in the infrared and (sub-)millimeter which are consistent with the observed optical/near-infrared emission in terms of energy balance. This allows us to estimate, for each galaxy, the (sub-)millimeter continuum flux densities in several ALMA, PdBI/NOEMA, and JVLA bands. As a consistency check, we verify that the 850 {mu}m number counts and extragalactic background light derived using our predictions are consistent with previous observations. Using empirical relations between the observed CO/[C II] line luminosities and the infrared luminosity of star-forming galaxies, we infer the luminosity of the CO(1-0) and [C II] lines from the estimated infrared luminosity of each galaxy in our sample

  10. Molecular thermal transistor: Dimension analysis and mechanism

    Science.gov (United States)

    Behnia, S.; Panahinia, R.

    2018-04-01

    Recently, large challenge has been spent to realize high efficient thermal transistors. Outstanding properties of DNA make it as an excellent nano material in future technologies. In this paper, we introduced a high efficient DNA based thermal transistor. The thermal transistor operates when the system shows an increase in the thermal flux despite of decreasing temperature gradient. This is what called as negative differential thermal resistance (NDTR). Based on multifractal analysis, we could distinguish regions with NDTR state from non-NDTR state. Moreover, Based on dimension spectrum of the system, it is detected that NDTR state is accompanied by ballistic transport regime. The generalized correlation sum (analogous to specific heat) shows that an irregular decrease in the specific heat induces an increase in the mean free path (mfp) of phonons. This leads to the occurrence of NDTR.

  11. EDITORIAL: Reigniting innovation in the transistor Reigniting innovation in the transistor

    Science.gov (United States)

    Demming, Anna

    2012-09-01

    Today the transistor is integral to the electronic circuitry that wires our lives. When Bardeen and Brattain first observed an amplified signal by connecting electrodes to a germanium crystal they saw that their 'semiconductor triode' could prove a useful alternative to the more cumbersome vacuum tubes used at the time [1]. But it was perhaps William Schottky who recognized the extent of the transistor's potential. A basic transistor has three or more terminals and current across one pair of terminals can switch or amplify current through another pair. Bardeen, Brattain and Schottky were jointly awarded a Nobel Prize in 1956 'for their researches on semiconductors and their discovery of the transistor effect' [2]. Since then many new forms of the transistor have been developed and understanding of the underlying properties is constantly advancing. In this issue Chen and Shih and colleagues at Taiwan National University and Drexel University report a pyroelectrics transistor. They show how a novel optothermal gating mechanism can modulate the current, allowing a range of developments in nanoscale optoelectronics and wireless devices [3]. The explosion of interest in nanoscale devices in the 1990s inspired electronics researchers to look for new systems that can act as transistors, such as carbon nanotube [4] and silicon nanowire [5] transistors. Generally these transistors function by raising and lowering an energy barrier of kBT -1, but researchers in the US and Canada have demonstrated that the quantum interference between two electronic pathways through aromatic molecules can also modulate the current flow [6]. The device has advantages for further miniaturization where energy dissipation in conventional systems may eventually cause complications. Interest in transistor technology has also led to advances in fabrication techniques for achieving high production quantities, such as printing [7]. Researchers in Florida in the US demonstrated field effect transistor

  12. Dual origin of room temperature sub-terahertz photoresponse in graphene field effect transistors

    Science.gov (United States)

    Bandurin, D. A.; Gayduchenko, I.; Cao, Y.; Moskotin, M.; Principi, A.; Grigorieva, I. V.; Goltsman, G.; Fedorov, G.; Svintsov, D.

    2018-04-01

    Graphene is considered as a promising platform for detectors of high-frequency radiation up to the terahertz (THz) range due to its superior electron mobility. Previously, it has been shown that graphene field effect transistors (FETs) exhibit room temperature broadband photoresponse to incoming THz radiation, thanks to the thermoelectric and/or plasma wave rectification. Both effects exhibit similar functional dependences on the gate voltage, and therefore, it was difficult to disentangle these contributions in previous studies. In this letter, we report on combined experimental and theoretical studies of sub-THz response in graphene field-effect transistors analyzed at different temperatures. This temperature-dependent study allowed us to reveal the role of the photo-thermoelectric effect, p-n junction rectification, and plasmonic rectification in the sub-THz photoresponse of graphene FETs.

  13. Transistor Small Signal Analysis under Radiation Effects

    International Nuclear Information System (INIS)

    Sharshar, K.A.A.

    2004-01-01

    A Small signal transistor parameters dedicate the operation of bipolar transistor before and after exposed to gamma radiation (1 Mrad up to 5 Mrads) and electron beam(1 MeV, 25 mA) with the same doses as a radiation sources, the electrical parameters of the device are changed. The circuit Model has been discussed.Parameters, such as internal emitter resistance (re), internal base resistance, internal collector resistance (re), emitter base photocurrent (Ippe) and base collector photocurrent (Ippe). These parameters affect on the operation of the device in its applications, which work as an effective element, such as current gain (hFE≡β)degradation it's and effective parameter in the device operation. Also the leakage currents (IcBO) and (IEBO) are most important parameters, Which increased with radiation doses. Theoretical representation of the change in the equivalent circuit for NPN and PNP bipolar transistor were discussed, the input and output parameters of the two types were discussed due to the change in small signal input resistance of the two types. The emitter resistance(re) were changed by the effect of gamma and electron beam irradiation, which makes a change in the role of matching impedances between transistor stages. Also the transistor stability factors S(Ico), S(VBE) and S(β are detected to indicate the transistor operations after exposed to radiation fields. In low doses the gain stability is modified due to recombination of induced charge generated during device fabrication. Also the load resistance values are connected to compensate the effect

  14. Lateral and Vertical Organic Transistors

    Science.gov (United States)

    Al-Shadeedi, Akram

    An extensive study has been performed to provide a better understanding of the operation principles of doped organic field-effect transistors (OFETs), organic p-i-n diodes, Schottky diodes, and organic permeable base transistors (OPBTs). This has been accomplished by a combination of electrical and structural characterization of these devices. The discussion of doped OFETs focuses on the shift of the threshold voltage due to increased doping concentrations and the generation and transport of minority charge carriers. Doping of pentacene OFETs is achieved by co-evaporation of pentacene with the n-dopant W2(hpp)4. It is found that pentacene thin film are efficiently doped and that a conductivity in the range of 2.6 x 10-6 S cm-1 for 1 wt% to 2.5 x 10-4 S cm-1 for 16 wt% is reached. It is shown that n-doped OFET consisting of an n-doped channel and n-doped contacts are ambipolar. This behavior is surprising, as n-doping the contacts should suppress direct injection of minority charge carriers (holes). It was proposed that minority charge carrier injection and hence the ambipolar characteristic of n-doped OFETs can be explained by Zener tunneling inside the intrinsic pentacene layer underneath the drain electrode. It is shown that the electric field in this layer is indeed in the range of the breakdown field of pentacene based p-i-n Zener homodiodes. Doping the channel has a profound influence on the onset voltage of minority (hole) conduction. The onset voltage can be shifted by lightly n-doping the channel. The shift of onset voltage can be explained by two mechanisms: first, due to a larger voltage that has to be applied to the gate in order to fully deplete the n-doped layer. Second, it can be attributed to an increase in hole trapping by inactive dopants. Moreover, it has been shown that the threshold voltage of majority (electron) conduction is shifted by an increase in the doping concentration, and that the ambipolar OFETs can be turned into unipolar OFETs at

  15. Graphene Field Effect Transistor for Radiation Detection

    Science.gov (United States)

    Li, Mary J. (Inventor); Chen, Zhihong (Inventor)

    2016-01-01

    The present invention relates to a graphene field effect transistor-based radiation sensor for use in a variety of radiation detection applications, including manned spaceflight missions. The sensing mechanism of the radiation sensor is based on the high sensitivity of graphene in the local change of electric field that can result from the interaction of ionizing radiation with a gated undoped silicon absorber serving as the supporting substrate in the graphene field effect transistor. The radiation sensor has low power and high sensitivity, a flexible structure, and a wide temperature range, and can be used in a variety of applications, particularly in space missions for human exploration.

  16. Fundamentals of RF and microwave transistor amplifiers

    CERN Document Server

    Bahl, Inder J

    2009-01-01

    A Comprehensive and Up-to-Date Treatment of RF and Microwave Transistor Amplifiers This book provides state-of-the-art coverage of RF and microwave transistor amplifiers, including low-noise, narrowband, broadband, linear, high-power, high-efficiency, and high-voltage. Topics covered include modeling, analysis, design, packaging, and thermal and fabrication considerations. Through a unique integration of theory and practice, readers will learn to solve amplifier-related design problems ranging from matching networks to biasing and stability. More than 240 problems are included to help read

  17. Switching Characteristics of Ferroelectric Transistor Inverters

    Science.gov (United States)

    Laws, Crystal; Mitchell, Coey; MacLeod, Todd C.; Ho, Fat D.

    2010-01-01

    This paper presents the switching characteristics of an inverter circuit using a ferroelectric field effect transistor, FeFET. The propagation delay time characteristics, phl and plh are presented along with the output voltage rise and fall times, rise and fall. The propagation delay is the time-delay between the V50% transitions of the input and output voltages. The rise and fall times are the times required for the output voltages to transition between the voltage levels V10% and V90%. Comparisons are made between the MOSFET inverter and the ferroelectric transistor inverter.

  18. Static Characteristics of the Ferroelectric Transistor Inverter

    Science.gov (United States)

    Mitchell, Cody; Laws, crystal; MacLeond, Todd C.; Ho, Fat D.

    2010-01-01

    The inverter is one of the most fundamental building blocks of digital logic, and it can be used as the foundation for understanding more complex logic gates and circuits. This paper presents the characteristics of an inverter circuit using a ferroelectric field-effect transistor. The voltage transfer characteristics are analyzed with respect to varying parameters such as supply voltage, input voltage, and load resistance. The effects of the ferroelectric layer between the gate and semiconductor are examined, and comparisons are made between the inverters using ferroelectric transistors and those using traditional MOSFETs.

  19. Going ballistic: Graphene hot electron transistors

    Science.gov (United States)

    Vaziri, S.; Smith, A. D.; Östling, M.; Lupina, G.; Dabrowski, J.; Lippert, G.; Mehr, W.; Driussi, F.; Venica, S.; Di Lecce, V.; Gnudi, A.; König, M.; Ruhl, G.; Belete, M.; Lemme, M. C.

    2015-12-01

    This paper reviews the experimental and theoretical state of the art in ballistic hot electron transistors that utilize two-dimensional base contacts made from graphene, i.e. graphene base transistors (GBTs). Early performance predictions that indicated potential for THz operation still hold true today, even with improved models that take non-idealities into account. Experimental results clearly demonstrate the basic functionality, with on/off current switching over several orders of magnitude, but further developments are required to exploit the full potential of the GBT device family. In particular, interfaces between graphene and semiconductors or dielectrics are far from perfect and thus limit experimental device integrity, reliability and performance.

  20. Stratospheric isotopic water profiles from a single submillimeter limb scan by TELIS

    Directory of Open Access Journals (Sweden)

    A. de Lange

    2009-08-01

    Full Text Available Around 490 GHz relatively strong HDO and H218O emission lines can be found in the submillimeter thermal-emission spectrum of the Earth's atmosphere, along with lines of the principal isotopologue of water vapour. These can be used for remote sensing of the rare/principal isotope ratio in the stratosphere. A sensitivity study has been performed for retrieval simulations of water isotopologues from balloon-borne measurements by the limb sounder TELIS (TErahertz and submillimeter LImb Sounder. The study demonstrates the capability of TELIS to determine, from a single limb scan, the profiles for H218O and HDO between 20 km and 37 km with a retrieval error of ≈3 and a spatial resolution of 1.5 km, as determined by the width of the averaging kernel. In addition HDO can be retrieved in the range of 10–20 km, albeit with a strongly deteriorated retrieval error. Expected uncertainties in instrumental parameters have only limited impact on the retrieval results.

  1. Micro combustion in sub-millimeter channels for novel modular thermophotovoltaic power generators

    International Nuclear Information System (INIS)

    Pan, J F; Tang, A K; Duan, L; Li, X C; Yang, W M; Chou, S K; Xue, H

    2010-01-01

    The performance of micro combustion-driven power systems is strongly influenced by the combustor structure. A novel modular thermophotovoltaic (TPV) power generator is presented, which is based on the sub-millimeter parallel plate combustor. It has the potential to achieve a high power density because of the high radiation energy per unit volume due to the high surface-to-volume ratio of the micro-combustor. The work experimentally investigated the ignition limitation for two micro-combustors. It also studied the effects of three major parameters on a sub-millimeter combustor, namely hydrogen to oxygen mixing ratio, hydrogen volumetric flow rate and nozzle geometry. The results show that the combustion efficiency decreases with the increase of the hydrogen flow rate, which is caused by reduced residence time. The average wall temperature with the rectangular nozzle is 25 K higher than that with the circle nozzle. The output electrical power and power density of the modular TPV power generator are projected to be 0.175 W and 0.0722 W cm −3 respectively. We experimentally achieve 0.166 W of electrical power, which is in good agreement with the model prediction

  2. Centralized operations and maintenance planning at the Atacama Large Millimeter/submillimeter Array (ALMA)

    Science.gov (United States)

    Lopez, Bernhard; Whyborn, Nicholas D.; Guniat, Serge; Hernandez, Octavio; Gairing, Stefan

    2016-07-01

    The Atacama Large Millimeter/submillimeter Array (ALMA) is a joint project between astronomical organizations in Europe, North America, and East Asia, in collaboration with the Republic of Chile. ALMA consists of 54 twelve-meter antennas and 12 seven-meter antennas operating as an aperture synthesis array in the (sub)millimeter wavelength range. Since the inauguration of the observatory back in March 2013 there has been a continuous effort to establish solid operations processes for effective and efficient management of technical and administrative tasks on site. Here a key aspect had been the centralized maintenance and operations planning: input is collected from science stakeholders, the computerized maintenance management system (CMMS) and from the technical teams spread around the world, then this information is analyzed and consolidated based on the established maintenance strategy, the observatory long-term plan and the short-term priorities definitions. This paper presents the high-level process that has been developed for the planning and scheduling of planned- and unplanned maintenance tasks, and for site operations like the telescope array reconfiguration campaigns. We focus on the centralized planning approach by presenting its genesis, its current implementation for the observatory operations including related planning products, and we explore the necessary next steps in order to fully achieve a comprehensive centralized planning approach for ALMA in steady-state operations.

  3. The excess flux in the cosmic submillimeter background radiation and the primordial deuterium abundance

    International Nuclear Information System (INIS)

    Dermer, C.D.; Guessoum, N.; National Aeronautics and Space Administration, Greenbelt, MD

    1989-01-01

    Recent measurements of the cosmic background radiation (CBR) show an enhanced flux in the submillimeter regime, compared to the spectrum of a 2.7 K blackbody. Thermal Comptonization of the relic radiation by a hot nonrelativistic plasma has long been known to produce distortions in the CBR spectrum, similar to what has now been observed. Heating of the primeval plasma to temperatures T ∼ 10 6 - 10 8 K could result from the injection of subcosmic ray protons at epoch z ∼ 10--100. The intensity of the subcosmic ray flux that provide conditions needed to explain the submillimeter excess by thermal Comptonization also leads to the production of cosmologically significant amounts of deuterium in collisions between subcosmic ray protons and primordial protons and α-particles. However, the amount of lithium produced through α-α reactions is in conflict with the observed Li abundance. If lithium is depleted, for example, by processing through Population II stars, arguments for the baryon content of the universe based on primordial deuterium and He abundances are weakened. 12 refs., 1 fig., 1 tab

  4. The status of MUSIC: the multiwavelength sub-millimeter inductance camera

    Science.gov (United States)

    Sayers, Jack; Bockstiegel, Clint; Brugger, Spencer; Czakon, Nicole G.; Day, Peter K.; Downes, Thomas P.; Duan, Ran P.; Gao, Jiansong; Gill, Amandeep K.; Glenn, Jason; Golwala, Sunil R.; Hollister, Matthew I.; Lam, Albert; LeDuc, Henry G.; Maloney, Philip R.; Mazin, Benjamin A.; McHugh, Sean G.; Miller, David A.; Mroczkowski, Anthony K.; Noroozian, Omid; Nguyen, Hien Trong; Schlaerth, James A.; Siegel, Seth R.; Vayonakis, Anastasios; Wilson, Philip R.; Zmuidzinas, Jonas

    2014-08-01

    The Multiwavelength Sub/millimeter Inductance Camera (MUSIC) is a four-band photometric imaging camera operating from the Caltech Submillimeter Observatory (CSO). MUSIC is designed to utilize 2304 microwave kinetic inductance detectors (MKIDs), with 576 MKIDs for each observing band centered on 150, 230, 290, and 350 GHz. MUSIC's field of view (FOV) is 14' square, and the point-spread functions (PSFs) in the four observing bands have 45'', 31'', 25'', and 22'' full-widths at half maximum (FWHM). The camera was installed in April 2012 with 25% of its nominal detector count in each band, and has subsequently completed three short sets of engineering observations and one longer duration set of early science observations. Recent results from on-sky characterization of the instrument during these observing runs are presented, including achieved map- based sensitivities from deep integrations, along with results from lab-based measurements made during the same period. In addition, recent upgrades to MUSIC, which are expected to significantly improve the sensitivity of the camera, are described.

  5. Shootthrough fault protection system for bipolar transistors in a voltage source transistor inverter

    International Nuclear Information System (INIS)

    Wirth, W.F.

    1982-01-01

    Faulted bipolar transistors in a voltage source transistor inverter are protected against shootthrough fault current, from the filter capacitor of the d-c voltage source which drives the inverter over the d-c bus, by interposing a small choke in series with the filter capacitor to limit the rate of rise of that fault current while at the same time causing the d-c bus voltage to instantly drop to essentially zero volts at the beginning of a shootthrough fault. In this way, the load lines of the faulted transistors are effectively shaped so that they do not enter the second breakdown area, thereby preventing second breakdown destruction of the transistors

  6. A DETAILED GRAVITATIONAL LENS MODEL BASED ON SUBMILLIMETER ARRAY AND KECK ADAPTIVE OPTICS IMAGING OF A HERSCHEL-ATLAS SUBMILLIMETER GALAXY AT z = 4.243 {sup ,} {sup ,}

    Energy Technology Data Exchange (ETDEWEB)

    Bussmann, R. S.; Gurwell, M. A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Fu Hai; Cooray, A. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Smith, D. J. B.; Bonfield, D.; Dunne, L. [Centre for Astrophysics, Science and Technology Research Institute, University of Hertfordshire, Hatfield, Herts AL10 9AB (United Kingdom); Dye, S.; Eales, S. [School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom); Auld, R. [Cardiff University, School of Physics and Astronomy, Queens Buildings, The Parade, Cardiff CF24 3AA (United Kingdom); Baes, M.; Fritz, J. [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, B-9000 Gent (Belgium); Baker, A. J. [Department of Physics and Astronomy, Rutgers, the State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854-8019 (United States); Cava, A. [Departamento de Astrofisica, Facultad de CC. Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Clements, D. L.; Dariush, A. [Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom); Coppin, K. [Department of Physics, McGill University, Ernest Rutherford Building, 3600 Rue University, Montreal, Quebec, H3A 2T8 (Canada); Dannerbauer, H. [Universitaet Wien, Institut fuer Astronomie, Tuerkenschanzstrasse 17, 1180 Wien, Oesterreich (Austria); De Zotti, G. [Universita di Padova, Dipto di Astronomia, Vicolo dell' Osservatorio 2, IT 35122, Padova (Italy); Hopwood, R., E-mail: rbussmann@cfa.harvard.edu [Department of Physics and Astronomy, Open University, Walton Hall, Milton Keynes, MK7 6AA (United Kingdom); and others

    2012-09-10

    We present high-spatial resolution imaging obtained with the Submillimeter Array (SMA) at 880 {mu}m and the Keck adaptive optics (AO) system at the K{sub S}-band of a gravitationally lensed submillimeter galaxy (SMG) at z = 4.243 discovered in the Herschel Astrophysical Terahertz Large Area Survey. The SMA data (angular resolution Almost-Equal-To 0.''6) resolve the dust emission into multiple lensed images, while the Keck AO K{sub S}-band data (angular resolution Almost-Equal-To 0.''1) resolve the lens into a pair of galaxies separated by 0.''3. We present an optical spectrum of the foreground lens obtained with the Gemini-South telescope that provides a lens redshift of z{sub lens} = 0.595 {+-} 0.005. We develop and apply a new lens modeling technique in the visibility plane that shows that the SMG is magnified by a factor of {mu} = 4.1 {+-} 0.2 and has an intrinsic infrared (IR) luminosity of L{sub IR} = (2.1 {+-} 0.2) Multiplication-Sign 10{sup 13} L{sub Sun }. We measure a half-light radius of the background source of r{sub s} = 4.4 {+-} 0.5 kpc which implies an IR luminosity surface density of {Sigma}{sub IR} (3.4 {+-} 0.9) Multiplication-Sign 10{sup 11} L{sub Sun} kpc{sup -2}, a value that is typical of z > 2 SMGs but significantly lower than IR luminous galaxies at z {approx} 0. The two lens galaxies are compact (r{sub lens} Almost-Equal-To 0.9 kpc) early-types with Einstein radii of {theta}{sub E1} 0.57 {+-} 0.01 and {theta}{sub E2} = 0.40 {+-} 0.01 that imply masses of M{sub lens1} = (7.4 {+-} 0.5) Multiplication-Sign 10{sup 10} M{sub Sun} and M{sub lens2} = (3.7 {+-} 0.3) Multiplication-Sign 10{sup 10} M{sub Sun }. The two lensing galaxies are likely about to undergo a dissipationless merger, and the mass and size of the resultant system should be similar to other early-type galaxies at z {approx} 0.6. This work highlights the importance of high spatial resolution imaging in developing models of strongly lensed galaxies

  7. High mobility and quantum well transistors design and TCAD simulation

    CERN Document Server

    Hellings, Geert

    2013-01-01

    For many decades, the semiconductor industry has miniaturized transistors, delivering increased computing power to consumers at decreased cost. However, mere transistor downsizing does no longer provide the same improvements. One interesting option to further improve transistor characteristics is to use high mobility materials such as germanium and III-V materials. However, transistors have to be redesigned in order to fully benefit from these alternative materials. High Mobility and Quantum Well Transistors: Design and TCAD Simulation investigates planar bulk Germanium pFET technology in chapters 2-4, focusing on both the fabrication of such a technology and on the process and electrical TCAD simulation. Furthermore, this book shows that Quantum Well based transistors can leverage the benefits of these alternative materials, since they confine the charge carriers to the high-mobility material using a heterostructure. The design and fabrication of one particular transistor structure - the SiGe Implant-Free Qu...

  8. Highly Crumpled All-Carbon Transistors for Brain Activity Recording.

    Science.gov (United States)

    Yang, Long; Zhao, Yan; Xu, Wenjing; Shi, Enzheng; Wei, Wenjing; Li, Xinming; Cao, Anyuan; Cao, Yanping; Fang, Ying

    2017-01-11

    Neural probes based on graphene field-effect transistors have been demonstrated. Yet, the minimum detectable signal of graphene transistor-based probes is inversely proportional to the square root of the active graphene area. This fundamentally limits the scaling of graphene transistor-based neural probes for improved spatial resolution in brain activity recording. Here, we address this challenge using highly crumpled all-carbon transistors formed by compressing down to 16% of its initial area. All-carbon transistors, chemically synthesized by seamless integration of graphene channels and hybrid graphene/carbon nanotube electrodes, maintained structural integrity and stable electronic properties under large mechanical deformation, whereas stress-induced cracking and junction failure occurred in conventional graphene/metal transistors. Flexible, highly crumpled all-carbon transistors were further verified for in vivo recording of brain activity in rats. These results highlight the importance of advanced material and device design concepts to make improvements in neuroelectronics.

  9. Transistor-based particle detection systems and methods

    Science.gov (United States)

    Jain, Ankit; Nair, Pradeep R.; Alam, Muhammad Ashraful

    2015-06-09

    Transistor-based particle detection systems and methods may be configured to detect charged and non-charged particles. Such systems may include a supporting structure contacting a gate of a transistor and separating the gate from a dielectric of the transistor, and the transistor may have a near pull-in bias and a sub-threshold region bias to facilitate particle detection. The transistor may be configured to change current flow through the transistor in response to a change in stiffness of the gate caused by securing of a particle to the gate, and the transistor-based particle detection system may configured to detect the non-charged particle at least from the change in current flow.

  10. Reconfigurable Complementary Logic Circuits with Ambipolar Organic Transistors.

    Science.gov (United States)

    Yoo, Hocheon; Ghittorelli, Matteo; Smits, Edsger C P; Gelinck, Gerwin H; Lee, Han-Koo; Torricelli, Fabrizio; Kim, Jae-Joon

    2016-10-20

    Ambipolar organic electronics offer great potential for simple and low-cost fabrication of complementary logic circuits on large-area and mechanically flexible substrates. Ambipolar transistors are ideal candidates for the simple and low-cost development of complementary logic circuits since they can operate as n-type and p-type transistors. Nevertheless, the experimental demonstration of ambipolar organic complementary circuits is limited to inverters. The control of the transistor polarity is crucial for proper circuit operation. Novel gating techniques enable to control the transistor polarity but result in dramatically reduced performances. Here we show high-performance non-planar ambipolar organic transistors with electrical control of the polarity and orders of magnitude higher performances with respect to state-of-art split-gate ambipolar transistors. Electrically reconfigurable complementary logic gates based on ambipolar organic transistors are experimentally demonstrated, thus opening up new opportunities for ambipolar organic complementary electronics.

  11. Ultimate response time of high electron mobility transistors

    International Nuclear Information System (INIS)

    Rudin, Sergey; Rupper, Greg; Shur, Michael

    2015-01-01

    We present theoretical studies of the response time of the two-dimensional gated electron gas to femtosecond pulses. Our hydrodynamic simulations show that the device response to a short pulse or a step-function signal is either smooth or oscillating time-decay at low and high mobility, μ, values, respectively. At small gate voltage swings, U 0  = U g  − U th , where U g is the gate voltage and U th is the threshold voltage, such that μU 0 /L < v s , where L is the channel length and v s is the effective electron saturation velocity, the decay time in the low mobility samples is on the order of L 2 /(μU 0 ), in agreement with the analytical drift model. However, the decay is preceded by a delay time on the order of L/s, where s is the plasma wave velocity. This delay is the ballistic transport signature in collision-dominated devices, which becomes important during very short time periods. In the high mobility devices, the period of the decaying oscillations is on the order of the plasma wave velocity transit time. Our analysis shows that short channel field effect transistors operating in the plasmonic regime can meet the requirements for applications as terahertz detectors, mixers, delay lines, and phase shifters in ultra high-speed wireless communication circuits

  12. Thermal transistor utilizing gas-liquid transition

    KAUST Repository

    Komatsu, Teruhisa S.

    2011-01-25

    We propose a simple thermal transistor, a device to control heat current. In order to effectively change the current, we utilize the gas-liquid transition of the heat-conducting medium (fluid) because the gas region can act as a good thermal insulator. The three terminals of the transistor are located at both ends and the center of the system, and are put into contact with distinct heat baths. The key idea is a special arrangement of the three terminals. The temperature at one end (the gate temperature) is used as an input signal to control the heat current between the center (source, hot) and another end (drain, cold). Simulating the nanoscale systems of this transistor, control of heat current is demonstrated. The heat current is effectively cut off when the gate temperature is cold and it flows normally when it is hot. By using an extended version of this transistor, we also simulate a primitive application for an inverter. © 2011 American Physical Society.

  13. Charge pumping in InAs nanowires by surface acoustic waves

    NARCIS (Netherlands)

    Roddaro, Stefano; Strambini, Elia; Romeo, Lorenzo; Piazza, Vincenzo; Nilsson, Kristian; Samuelson, Lars; Beltram, Fabio

    2010-01-01

    We investigate the interaction between surface acoustic waves on a piezoelectric LiNbO3 substrate and charge carriers in InAs nanowire transistors. Interdigital transducers are used to excite electromechanical waves on the chip surface and their influence on the transport in the nanowire devices is

  14. Collective CO2 laser scattering on moving discharge structures in the submillimeter range in a magnetohydrodynamic generator

    NARCIS (Netherlands)

    de Haas, J.C.M.; Schenkelaars, H.J.W.; vd Mortel, P.J.; Schram, D.C.; Veefkind, A.

    1986-01-01

    Collective scattering of CO/sub 2/ laser light on electrons is used to determine the radial scale length of the discharge structures occurring in a closed cycle magnetohydrodynamic generator. Heterodyne detection of scattered radiation is used to obtain a spatial resolution in the submillimeter

  15. The JCMT Transient Survey: Detection of Submillimeter Variability in a Class I Protostar EC 53 in Serpens Main

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Hyunju; Cho, Jungyeon [Department of Astronomy and Space Science, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134 (Korea, Republic of); Lee, Jeong-Eun [School of Space Research, Kyung Hee University, 1732, Deogyeong-Daero, Giheung-gu Yongin-shi, Gyunggi-do 17104 (Korea, Republic of); Mairs, Steve; Johnstone, Doug [Department of Physics and Astronomy, University of Victoria, Victoria, BC, V8P 1A1 (Canada); Herczeg, Gregory J. [Kavli Institute for Astronomy and Astrophysics, Peking University, Yiheyuan 5, Haidian Qu, 100871 Beijing (China); Kang, Sung-ju; Kang, Miju, E-mail: jeongeun.lee@khu.ac.kr [Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055 (Korea, Republic of); Collaboration: JCMT Transient Team

    2017-11-01

    During the protostellar phase of stellar evolution, accretion onto the star is expected to be variable, but this suspected variability has been difficult to detect because protostars are deeply embedded. In this paper, we describe a submillimeter luminosity burst of the Class I protostar EC 53 in Serpens Main, the first variable found during our dedicated JCMT/SCUBA-2 monitoring program of eight nearby star-forming regions. EC 53 remained quiescent for the first six months of our survey, from 2016 February to August. The submillimeter emission began to brighten in 2016 September, reached a peak brightness of 1.5 times the faint state, and has been decaying slowly since 2017 February. The change in submillimeter brightness is interpreted as dust heating in the envelope, generated by a luminosity increase of the protostar of a factor of ≥4. The 850 μ m light curve resembles the historical K -band light curve, which varies by a factor of ∼6 with a 543 period and is interpreted as accretion variability excited by interactions between the accretion disk and a close binary system. The predictable detections of accretion variability observed at both near-infrared and submillimeter wavelengths make the system a unique test-bed, enabling us to capture the moment of the accretion burst and to study the consequences of the outburst on the protostellar disk and envelope.

  16. The Atacama Large Millimeter/Submillimeter Array (ALMA) - A Successful Three-Way International Partnership Without a Majority Stakeholder

    Science.gov (United States)

    Vanden Bout, Paul A.

    2013-04-01

    The Atacama Millimeter/Submillimeter Array (ALMA) is the largest ground-based astronomical facility built to date. It's size and challenging site required an international effort. This talk presents the partnership structure, management challenges, current status, and examples of early scientific successes.

  17. The Integration and Applications of Organic Thin Film Transistors and Ferroelectric Polymers

    Science.gov (United States)

    Hsu, Yu-Jen

    Organic thin film transistors and ferroelectric polymer (polyvinylidene difluoride) sheet material are integrated to form various sensors for stress/strain, acoustic wave, and Infrared (heat) sensing applications. Different from silicon-based transistors, organic thin film transistors can be fabricated and processed in room-temperature and integrated with a variety of substrates. On the other hand, polyvinylidene difluoride (PVDF) exhibits ferroelectric properties that are highly useful for sensor applications. The wide frequency bandwidth (0.001 Hz to 10 GHz), vast dynamic range (100n to 10M psi), and high elastic compliance (up to 3 percent) make PVDF a more suitable candidate over ceramic piezoelectric materials for thin and flexible sensor applications. However, the low Curie temperature may have impeded its integration with silicon technology. Organic thin film transistors, however, do not have the limitation of processing temperature, hence can serve as transimpedance amplifiers to convert the charge signal generated by PVDF into current signal that are more measurable and less affected by any downstream parasitics. Piezoelectric sensors are useful for a range of applications, but passive arrays suffer from crosstalk and signal attenuation which have complicated the development of array-based PVDF sensors. We have used organic field effect transistors, which are compatible with the low Curie temperature of a flexible piezoelectric polymer,PVDF, to monolithically fabricate transimpedance amplifiers directly on the sensor surface and convert the piezoelectric charge signal into a current signal which can be detected even in the presence of parasitic capacitances. The device couples the voltage generated by the PVDF film under strain into the gate of the organic thin film transistors (OFET) using an arrangement that allows the full piezoelectric voltage to couple to the channel, while also increasing the charge retention time. A bipolar detector is created by

  18. LOOKING INTO THE HEARTS OF BOK GLOBULES: MILLIMETER AND SUBMILLIMETER CONTINUUM IMAGES OF ISOLATED STAR-FORMING CORES

    International Nuclear Information System (INIS)

    Launhardt, R.; Henning, Th.; Khanzadyan, T.; Schmalzl, M.; Wolf, S.; Nutter, D.; Ward-Thompson, D.; Bourke, T. L.; Zylka, R.

    2010-01-01

    We present the results of a comprehensive infrared, submillimeter, and millimeter continuum emission study of isolated low-mass star-forming cores in 32 Bok globules, with the aim to investigate the process of star formation in these regions. The submillimeter and millimeter dust continuum emission maps together with the spectral energy distributions are used to model and derive the physical properties of the star-forming cores, such as luminosities, sizes, masses, densities, etc. Comparisons with ground-based near-infrared and space-based mid- and far-infrared images from Spitzer are used to reveal the stellar content of the Bok globules, association of embedded young stellar objects (YSOs) with the submillimeter dust cores, and the evolutionary stages of the individual sources. Submillimeter dust continuum emission was detected in 26 out of the 32 globule cores observed. For 18 globules with detected (sub)millimeter cores, we derive evolutionary stages and physical parameters of the embedded sources. We identify nine starless cores, most of which are presumably prestellar, nine Class 0 protostars, and twelve Class I YSOs. Specific source properties like bolometric temperature, core size, and central densities are discussed as a function of evolutionary stage. We find that at least two thirds (16 out of 24) of the star-forming globules studied here show evidence of forming multiple stars on scales between 1000 and 50,000 AU. However, we also find that most of these small prototstar and star groups are comprised of sources with different evolutionary stages, suggesting a picture of slow and sequential star formation in isolated globules.

  19. Application of an ultrasonic focusing radiator for acoustic levitation of submillimeter samples

    Science.gov (United States)

    Lee, M. C.

    1981-01-01

    An acoustic apparatus has been specifically developed to handle samples of submillimeter size in a gaseous medium. This apparatus consists of an acoustic levitation device, deployment devices for small liquid and solid samples, heat sources for sample heat treatment, acoustic alignment devices, a cooling system and data-acquisition instrumentation. The levitation device includes a spherical aluminum dish of 12 in. diameter and 0.6 in. thickness, 130 pieces of PZT transducers attached to the back side of the dish and a spherical concave reflector situated in the vicinity of the center of curvature of the dish. The three lowest operating frequencies for the focusing-radiator levitation device are 75, 105 and 163 kHz, respectively. In comparison with other levitation apparatus, it possesses a large radiation pressure and a high lateral positional stability. This apparatus can be used most advantageously in the study of droplets and spherical shell systems, for instance, for fusion target applications.

  20. A dynamic method for continuously measuring magnetic field profiles in planar micropole undulators with submillimeter gaps

    International Nuclear Information System (INIS)

    Tatchyn, R.; Oregon Univ., Eugene

    1989-01-01

    Conventional techniques for measuring magnetic field profiles in ordinary undulators rely predominantly on Hall probes for making point-by-point static measurements. As undulators with submillimeter periods and gaps become available, such techniques will start becoming untenable, due to the relative largeness of conventional Hall probe heads and the rapidly increasing number of periods in devices of fixed length. In this paper a method is presented which can rapidly map out field profiles in undulators with periods and gaps extending down to the 100 μm range and beyond. The method, which samples the magnetic field continuously, has been used successfully in profiling a recently constructed 726 μm period undulator, and seems to offer some potential advantages over conventional Hall probe techniques in measuring large-scale undulator fields as well. (orig.)

  1. A millisecond-risetime sub-millimeter light source for lab and in flight bolometer calibration

    Science.gov (United States)

    Abbon, Ph.; Delbart, A.; Fesquet, M.; Magneville, C.; Mazeau, B.; Pansart, J.-P.; Yvon, D.; Dumoulin, L.; Marnieros, S.; Camus, Ph.; Durand, T.; Hoffmann, Ch.

    2007-06-01

    The Olimpo balloon project will use a 120 bolometer camera to observe the sky at four frequencies (143, 217, 385 and 600 GHz) with a resolution of 3 to 2 arc-minute. This paper presents the sub-millimeter calibration "lamp" developed for ground testing and in-flight secondary calibration of bolometric detectors. By design, main features of the device are reproducibility and stability of light flux and millisecond rise time. The radiative device will be placed inside the bolometer camera and will illuminate the bolometer array through a hole in the last 2 K mirror. Operation, readout, and monitoring of the device is ensured by warm electronics. Light output flux and duration is programmable, triggered and monitored from a simple computer RS232 interface. It was tested to be reliable in ballooning temperature conditions from -80 to 50C. Design and test's results are explained.

  2. Far-infrared and submillimeter brightness temperatures of the giant planets

    International Nuclear Information System (INIS)

    Hildebrand, R.H.; Loewenstein, R.F.; Harper, D.A.; Orton, G.S.; Keene, J.; Yerkes Observatory, Williams Bay, WI; California Institute of Technology, Jet Propulsion Laboratory, Pasadena; California Institute of Technology, Pasadena)

    1985-01-01

    The brightness temperatures of Jupiter, Saturn, Uranus, and Neptune were measured in the 35-1000 micron range with the 3-m NASA Infrared Telescope Facility (at wavelengths greater than 350 microns) and with the Kuiper Airborne Observatory (at wavelengths less than 350 microns). The data indicate the presence in Jupiter's spectrum of excess radiation (compared to theoretical models) at 300-400 microns. In addition, slightly less flux was observed from Saturn at 200 microns than predicted by atmospheric models, which suggests the possible presence of an unmodeled absorber. The submillimeter fluxes from Uranus and Neptune appear to be most consistent with low mixing ratios (less than 1 percent) of CH 4 in their deep atmospheres. 73 refs

  3. Fabrication and Testing of Carbon Fiber, Graphite-Epoxy Panels for Submillimeter Telescope Use

    Science.gov (United States)

    Rieger, H.; Helwig, G.; Parks, R. E.; Ulich, B. L.

    1983-12-01

    An experimental carbon-fiber, graphite-epoxy, aluminum Flexcore sandwich panel roughly 1-m square was made by Dornier System, Friedrichshafen, West Germany. The panel was a pre-prototype of the panels to be used in the dish of the 10-m diameter Sub-Millimeter Telescope, a joint project of the Max-Planck-Institute fur Radioastronomie, Bonn, West Germany, and Steward Observatory, the University of Arizona in Tucson. This paper outlines the fabrication process for the panel and indicates the surface accuracy of the panel replication process. To predict the behavior of the panel under various environmental loads, the panel was modeled structurally using anisotropic elements for the core material. Results of this analysis along with experimental verification of these predictions are also given.

  4. In situ production of microporous foams in sub-millimeter cylindrical gold targets

    International Nuclear Information System (INIS)

    Fan Yongheng; Luo Xuan; Fang Yu; Ren Hongbo; Yuan Guanghui; Wang Honglian; Zhou Lan; Zhang Lin; Du Kai

    2009-01-01

    The preparation of microcellular foam in sub-millimeter cylindrical gold targets is described. Small, open-ended, gold cylinders of 400 μm diameter, 700 μm length, and 20 μm wall thickness were fabricated by electroplating gold onto a silicon bronze mandrel and leaching the mandrel with concentrated nitric acid. After several rinsing and cleaning steps, the cylinders were filled with a solution containing acrylate monomers. The solution was polymerized in situ with ultraviolet light to produce a gel. Precipitation of these gels in a non-solvent such as methanol and subsequent drying by means of a critical point drying apparatus produced cylinders filled with microporous foams. The foams have densities of 50 mg · cm -3 and cell sizes on more than 1 μm. They fill the cylinders completely without shrinkage during the drying process, and need no subsequent machining. (authors)

  5. Submillimeter vibrationally excited water emission from the peculiar red supergiant VY Canis Majoris

    Science.gov (United States)

    Menten, K. M.; Philipp, S. D.; Güsten, R.; Alcolea, J.; Polehampton, E. T.; Brünken, S.

    2006-08-01

    Context: .Vibrationally excited emission from the SiO and H2O molecules probes the innermost circumstellar envelopes of oxygen-rich red giant and supergiant stars. VY CMa is the most prolific known emission source in these molecules. Aims: .Observations were made to search for rotational lines in the lowest vibrationally excited state of H2O. Methods: .The APEX telescope was used for observations of H2O lines at frequencies around 300 GHz. Results: .Two vibrationally excited H2O lines were detected, a third one could not be found. In one of the lines we find evidence for weak maser action, similar to known (sub)millimeter ν2 = 1 lines. We find that the other line's intensity is consistent with thermal excitation by the circumstellar infrared radiation field. Several SiO lines were detected together with the H2O lines.

  6. Logarithmic unification from symmetries enhanced in the sub-millimeter infrared

    International Nuclear Information System (INIS)

    Arkani-Hamed, Nima; Dimopoulos, Savas; March-Russell, John

    1999-01-01

    In theories with TeV string scale and sub-millimeter extra dimensions the attractive picture of logarithmic gauge coupling unification at 10 16 GeV is seemingly destroyed. In this paper we argue to the contrary that logarithmic unification can occur in such theories. The rationale for unification is no longer that a gauge symmetry is restored at short distances, but rather that a geometric symmetry is restored at large distances in the bulk away from our 3-brane. The apparent ''running'' of the gauge couplings to energies far above the string scale actually arises from the logarithmic variation of classical fields in (sets of) two large transverse dimensions. We present a number of N = 2 and N = 1 supersymmetric D-brane constructions illustrating this picture for unification

  7. Infrared and submillimeter space missions in the coming decade programmes, programmatics, and technology

    CERN Document Server

    Sauvage, Marc; Gallais, Pascal; Vigroux, Laurent

    1996-01-01

    A revolution similar to that brought by CCDs to visible astronomy is still ahead in IR and submillimeter astronomy. There is certainly no wavelength range which has, over the past several years, seen such impressive advances in technology: large-scale detector arrays, new designs for cooling in space, lightweight mirror technologies. Scientific cases for observing the cold universe are outstanding. Observations in the FIR/Submm range will provide answers to such fundamental questions as: What is the spectrum of the primordial fluctuations? How do primeval galaxies look? What are the first stages of star formation? Most of the international space missions that have been triggered by these questions are presented in detail here. Technological issues raised by these missions are reviewed, as are the most recent achievements in cooling and detector technologies.

  8. Interpretation of electron beam induced charging of oxide layers in a transistor studied using electron holography

    DEFF Research Database (Denmark)

    Ubaldi, F; Pozzi, G; Kasama, Takeshi

    2010-01-01

    Off-axis electron holography has been used to characterize a linear array of transistors, which was prepared for examination in cross-sectional geometry in the transmission electron microscope using focused ion beam milling. In reconstructed phase images, regions of silicon oxide that are located...... into account the mean inner potential of the specimen and the perturbed vacuum reference wave. The simulations suggest that the oxide layers contain a uniform volume density of positive charge and that the elliptical contours result from the combined effect of the electrostatic potential in the specimen...

  9. Discovery of a Lensed Ultrabright Submillimeter Galaxy at z = 2.0439

    Science.gov (United States)

    Díaz-Sánchez, A.; Iglesias-Groth, S.; Rebolo, R.; Dannerbauer, H.

    2017-07-01

    We report an ultrabright lensed submillimeter galaxy (SMG) at z = 2.0439, WISE J132934.18+224327.3, identified as a result of a full-sky cross-correlation of the AllWISE and Planck compact source catalogs aimed to search for bright analogs of the SMG SMM J2135, the Cosmic Eyelash. Inspection of archival SCUBA-2 observations of the candidates revealed a source with fluxes ({S}850μ {{m}}=130 mJy) consistent with the Planck measurements. The centroid of the SCUBA-2 source coincides within 1 arcsec with the position of the AllWISE mid-IR source, and, remarkably, with an arc-shaped lensed galaxy in HST images at visible wavelengths. Low-resolution rest-frame UV-optical spectroscopy of this lensed galaxy obtained with 10.4 m GTC reveals the typical absorption lines of a starburst galaxy. Gemini-N near-IR spectroscopy provided a clear detection of {{{H}}}α emission. The lensed source appears to be gravitationally magnified by a massive foreground galaxy cluster lens at z = 0.44 modeling with Lenstool indicates a lensing amplification factor of 11 ± 2. We determine an intrinsic rest-frame 8-1000 μm luminosity, {L}{IR}, of (1.3+/- 0.1)× {10}13 {L}⊙ , and a likely star formation rate (SFR) of ˜ 500{--}2000 {M}⊙ {{yr}}-1. The SED shows a remarkable similarity with the Cosmic Eyelash from optical-mid/IR to submillimeter/radio, albeit at higher fluxes.

  10. Imaging the environment of a z = 6.3 submillimeter galaxy with SCUBA-2

    Energy Technology Data Exchange (ETDEWEB)

    Robson, E. I.; Holland, W. S. [United Kingdom Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Ivison, R. J. [European Space Observatory, Karl Schwarzschild Strasse 2, D-85748 Garching (Germany); Smail, Ian [Institute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE (United Kingdom); Geach, J. E. [Centre for Astrophysics Research, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Gibb, A. G. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Riechers, D. [Astronomy Department, Cornell University, Ithaca, NY 14853 (United States); Ade, P. A. R. [Astronomy and Instrumentation Group, Cardiff University, Cardiff, Wales CF10 3XQ (United Kingdom); Bintley, D. [Joint Astronomy Centre, 660 North Ahoku Place, University Park, Hilo, HI 96720 (United States); Bock, J. [Jet Propulsion Laboratory, National Aeronautics and Space Administration, Pasadena, CA 91109 (United States); Chapin, E. L. [XMM-Newton Science Operations Centre, European Space Astronomy Centre, Apartado 79, E-28691 Villaneueva de la Canada, Madrid (Spain); Chapman, S. C. [Department of Physics and Atmospheric Science, Dalhousie University, Coburg Road, Halifax B3H 1A6 (Canada); Clements, D. L. [Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom); Conley, A. [Center for Astrophysics and Space Astronomy, 389 UCB, University of Colorado, Boulder, CO 80309 (United States); Cooray, A. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Dunlop, J. S. [Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Farrah, D., E-mail: rob.ivison@gmail.com [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); and others

    2014-09-20

    We describe a search for submillimeter emission in the vicinity of one of the most distant, luminous galaxies known, HerMES FLS3, at z = 6.34, exploiting it as a signpost to a potentially biased region of the early universe, as might be expected in hierarchical structure formation models. Imaging to the confusion limit with the innovative, wide-field submillimeter bolometer camera, SCUBA-2, we are sensitive to colder and/or less luminous galaxies in the surroundings of HFLS3. We use the Millennium Simulation to illustrate that HFLS3 may be expected to have companions if it is as massive as claimed, but find no significant evidence from the surface density of SCUBA-2 galaxies in its vicinity, or their colors, that HFLS3 marks an overdensity of dusty, star-forming galaxies. We cannot rule out the presence of dusty neighbors with confidence, but deeper 450 μm imaging has the potential to more tightly constrain the redshifts of nearby galaxies, at least one of which likely lies at z ≳ 5. If associations with HFLS3 can be ruled out, this could be taken as evidence that HFLS3 is less biased than a simple extrapolation of the Millennium Simulation may imply. This could suggest either that it represents a rare short-lived, but highly luminous, phase in the evolution of an otherwise typical galaxy, or that this system has suffered amplification due to a foreground gravitational lens and so is not as intrinsically luminous as claimed.

  11. Diffusion in and around alginate and chitosan films with embedded sub-millimeter voids

    Energy Technology Data Exchange (ETDEWEB)

    Patra, Subhajit; Bal, Dharmendra Kumar; Ganguly, Somenath, E-mail: snganguly@che.iitkgp.ernet.in

    2016-02-01

    Hydrogel scaffolds from biopolymers have potential use in the controlled release of drugs, and as 3-D structure for the formation of tissue matrix. This article describes the solute release behavior of alginate and chitosan films with embedded voids of sub-millimeter dimensions. Nitrogen gas was bubbled in a fluidic arrangement to generate bubbles, prior to the crosslinking. The crosslinked gel was dried in a vacuum oven, and subsequently, soaked in Vitamin B-12 solution. The dimensions of the voids immediately after the cross-linking of gel, and also after complete drying were obtained using a digital microscope and scanning electron microscope respectively. The porosity of the gel was measured gravimetrically. The release of Vitamin B-12 in PBS buffer on a shaker was studied. The release experiments were repeated at an elevated temperature of 37 °C in the presence of lysozyme. The diffusion coefficient within the gel layer and the mass transfer coefficient at the interface with the bulk-liquid were estimated using a mathematical model. For comparison, the experiment was repeated with a film that does not have any embedded void. The enhancement in diffusion coefficient due to the presence of voids is discussed in this article. - Highlights: • Formation of sub-millimeter voids in biopolymer films using fluidic arrangement • The retention of self-assembled bubbles in films after crosslinking, and drying • The enhancement observed in release of model drug with introduction of voids • The diffusion coefficients in and around biopolymer films from model regression • Use of classical model in explaining release profiles from dual porosity media.

  12. Advantages of cortical surface reconstruction using submillimeter 7 T MEMPRAGE.

    Science.gov (United States)

    Zaretskaya, Natalia; Fischl, Bruce; Reuter, Martin; Renvall, Ville; Polimeni, Jonathan R

    2018-01-15

    Recent advances in MR technology have enabled increased spatial resolution for routine functional and anatomical imaging, which has created demand for software tools that are able to process these data. The availability of high-resolution data also raises the question of whether higher resolution leads to substantial gains in accuracy of quantitative morphometric neuroimaging procedures, in particular the cortical surface reconstruction and cortical thickness estimation. In this study we adapted the FreeSurfer cortical surface reconstruction pipeline to process structural data at native submillimeter resolution. We then quantified the differences in surface placement between meshes generated from (0.75 mm) 3 isotropic resolution data acquired in 39 volunteers and the same data downsampled to the conventional 1 mm 3 voxel size. We find that when processed at native resolution, cortex is estimated to be thinner in most areas, but thicker around the Cingulate and the Calcarine sulci as well as in the posterior bank of the Central sulcus. Thickness differences are driven by two kinds of effects. First, the gray-white surface is found closer to the white matter, especially in cortical areas with high myelin content, and thus low contrast, such as the Calcarine and the Central sulci, causing local increases in thickness estimates. Second, the gray-CSF surface is placed more interiorly, especially in the deep sulci, contributing to local decreases in thickness estimates. We suggest that both effects are due to reduced partial volume effects at higher spatial resolution. Submillimeter voxel sizes can therefore provide improved accuracy for measuring cortical thickness. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. THE HAWAII SCUBA-2 LENSING CLUSTER SURVEY: NUMBER COUNTS AND SUBMILLIMETER FLUX RATIOS

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Li-Yen; Cowie, Lennox L.; Barger, Amy J. [Institute of Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Chen, Chian-Chou [Center for Extragalactic Astronomy, Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Wang, Wei-Hao [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China)

    2016-09-20

    We present deep number counts at 450 and 850 μ m using the SCUBA-2 camera on the James Clerk Maxwell Telescope. We combine data for six lensing cluster fields and three blank fields to measure the counts over a wide flux range at each wavelength. Thanks to the lensing magnification, our measurements extend to fluxes fainter than 1 mJy and 0.2 mJy at 450 μ m and 850 μ m, respectively. Our combined data highly constrain the faint end of the number counts. Integrating our counts shows that the majority of the extragalactic background light (EBL) at each wavelength is contributed by faint sources with L {sub IR} < 10{sup 12} L {sub ⊙}, corresponding to luminous infrared galaxies (LIRGs) or normal galaxies. By comparing our result with the 500 μ m stacking of K -selected sources from the literature, we conclude that the K -selected LIRGs and normal galaxies still cannot fully account for the EBL that originates from sources with L {sub IR} < 10{sup 12} L {sub ⊙}. This suggests that many faint submillimeter galaxies may not be included in the UV star formation history. We also explore the submillimeter flux ratio between the two bands for our 450 μ m and 850 μ m selected sources. At 850 μ m, we find a clear relation between the flux ratio and the observed flux. This relation can be explained by a redshift evolution, where galaxies at higher redshifts have higher luminosities and star formation rates. In contrast, at 450 μ m, we do not see a clear relation between the flux ratio and the observed flux.

  14. The CCAT-prime Extreme Field-of-View Submillimeter Telescope on Cerro Chajnantor

    Science.gov (United States)

    Koopman, Brian; Bertoldi, Frank; Chapman, Scott; Fich, Michel; Giovanelli, Riccardo; Haynes, Martha P.; Herter, Terry L.; Murray, Norman W.; Niemack, Michael D.; Riechers, Dominik; Schilke, Peter; Stacey, Gordon J.; Stutzki, Juergen; CCAT-prime Collaboration

    2017-01-01

    CCAT-prime is a six meter aperture off-axis submillimeter telescope that we plan to build at 5600m elevation on Cerro Chajnantor in Chile. The CCAT-prime optics are based on a cross-Dragone design with high throughput and a wide field-of-view optimized to increase the mapping speed of next generation cosmic microwave background (CMB) observations. These characteristics make CCAT-prime an excellent platform for a wide range of next generation millimeter and submillimeter science goals, and a potential platform for CMB stage-IV measurements. Here we present the telescope design for CCAT-prime and review the science goals.Taking advantage of the high elevation site, the first generation instrument for CCAT-prime will measure seven different frequency bands from 350um to 3mm. These seven bands will enable precise measurements of the Sunyaev-Zel’dovich effects (SZE) by separating contributions from CMB, thermal SZE, kinetic SZE, bright submm galaxies, and radio sources with a goal of extracting the peculiar velocities from a large number of galaxy clusters. Additional science priorities for CCAT-prime include: Galactic Ecology studies of the dynamic intersteller medium by mapping the fine structure lines [CI], [CII] and [NII] as well as high-excitation CO lines at the shortest wavelength bands; high redshift intensity mapping of [CII] emission from star-forming galaxies that likely dominates cosmic reionization at z~5-9 to probe the Epoch of Reionization; and next generation CMB polarization measurements to constrain inflation and cosmological models. The CCAT-prime facility will further our understanding of astrophysical processes from moments after the Big Bang to the present-day evolution of the Milky Way.

  15. Sub-millimeter scale magnetostratigraphy and environmental magnetism of ferromanganese crusts using a scanning SQUID microscope

    Science.gov (United States)

    Oda, H.; Noguchi, A.; Yamamoto, Y.; Usui, A.; Ito, T.; Kawai, J.; Takahashi, H.

    2017-12-01

    Ferromanganese crusts are chemical sedimentary rock composed mainly of iron-manganese oxide. Because the ferromanganese crusts grow very slowly on the sea floor at rates of 3-10 mm/Ma, long-term deep-sea environmental changes can be reconstructed from the ferromanganese crusts. Thus, it is important to provide reliable age model for the crusts. For the past decades 10Be/9Be dating method has been used extensively to give age models for crusts younger than 15 Ma. Alternatively, sub-millimeter scale magnetostratigraphic study on a ferromanganese crust sample using a scanning SQUID (superconducting quantum interference device) microscope (Kawai et al., 2016; Oda et al., 2016) has been applied successfully (e.g. Oda et al., 2011; Noguchi et al. 2017). Also, environmental magnetic mapping was successful for the ferromanganese crust from the Takuyo Daigo Seamount (Noguchi et al., 2017). The ferromanganese crust used in this study was sampled from the Hanzawa Seamount, Ryukyu trench and the Shotoku Seamount. The vertical component of the magnetic field above thin section samples of the ferromanganese crust was measured using the scanning SQUID microscope on 100 μm grids. Magnetic mapping of the Hanzawa Seamount shows sub-millimeter scale magnetic stripes parallel to lamina. By correlating the boundaries of magnetic stripes with known geomagnetic reversals, we estimated that average growth rate of the Hanzawa Seamount is 2.67 +/- 0.04 mm/Ma , which is consistent with that deduced from the 10Be/9Be dating method (2.56 +/- 0.04 mm/Ma). The crust sample from the Shotoku Seamount used by Oda et al. (2011) shows prominent periodical lamination. Further details are going to be discussed together with the environmental magnetic mapping.

  16. CORRELATIONS IN THE (SUB)MILLIMETER BACKGROUND FROM ACT Multiplication-Sign BLAST

    Energy Technology Data Exchange (ETDEWEB)

    Hajian, Amir; Battaglia, Nick; Bond, J. Richard [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON M5S 3H8 (Canada); Viero, Marco P.; Bock, James J. [California Institute of Technology, Pasadena, CA 91125 (United States); Addison, Graeme [Department of Astrophysics, Oxford University, Oxford, OX1 3RH (United Kingdom); Aguirre, Paula [Departamento de Astronomia y Astrofisica, Facultad de Fisica, Pontificia Universidad Catolica, Casilla 306, Santiago 22 (Chile); Appel, John William; Duenner, Rolando; Essinger-Hileman, Thomas; Fowler, Joseph W.; Hincks, Adam D. [Joseph Henry Laboratories of Physics, Jadwin Hall, Princeton University, Princeton, NJ 08544 (United States); Das, Sudeep; Dunkley, Joanna [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States); Devlin, Mark J.; Dicker, Simon R. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States); Hughes, John P. [Department of Physics and Astronomy, Rutgers, State University of New Jersey, Piscataway, NJ 08854-8019 (United States); Halpern, Mark [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z4 (Canada); Hasselfield, Matthew [Laboratoire APC, Universite Paris Diderot, 75205 Paris (France); Hilton, Matt [Astrophysics and Cosmology Research Unit, School of Mathematical Sciences, University of KwaZulu-Natal, Durban 4041 (South Africa); and others

    2012-01-01

    We present measurements of the auto- and cross-frequency correlation power spectra of the cosmic (sub)millimeter background at 250, 350, and 500 {mu}m (1200, 860, and 600 GHz) from observations made with the Balloon-borne Large Aperture Submillimeter Telescope (BLAST); and at 1380 and 2030 {mu}m (218 and 148 GHz) from observations made with the Atacama Cosmology Telescope (ACT). The overlapping observations cover 8.6 deg{sup 2} in an area relatively free of Galactic dust near the south ecliptic pole. The ACT bands are sensitive to radiation from the cosmic microwave background, to the Sunyaev-Zel'dovich effect from galaxy clusters, and to emission by radio and dusty star-forming galaxies (DSFGs), while the dominant contribution to the BLAST bands is from DSFGs. We confirm and extend the BLAST analysis of clustering with an independent pipeline and also detect correlations between the ACT and BLAST maps at over 25{sigma} significance, which we interpret as a detection of the DSFGs in the ACT maps. In addition to a Poisson component in the cross-frequency power spectra, we detect a clustered signal at 4{sigma}, and using a model for the DSFG evolution and number counts, we successfully fit all of our spectra with a linear clustering model and a bias that depends only on redshift and not on scale. Finally, the data are compared to, and generally agree with, phenomenological models for the DSFG population. This study demonstrates the constraining power of the cross-frequency correlation technique to constrain models for the DSFGs. Similar analyses with more data will impose tight constraints on future models.

  17. Imaging the environment of a z = 6.3 submillimeter galaxy with SCUBA-2

    International Nuclear Information System (INIS)

    Robson, E. I.; Holland, W. S.; Ivison, R. J.; Smail, Ian; Geach, J. E.; Gibb, A. G.; Riechers, D.; Ade, P. A. R.; Bintley, D.; Bock, J.; Chapin, E. L.; Chapman, S. C.; Clements, D. L.; Conley, A.; Cooray, A.; Dunlop, J. S.; Farrah, D.

    2014-01-01

    We describe a search for submillimeter emission in the vicinity of one of the most distant, luminous galaxies known, HerMES FLS3, at z = 6.34, exploiting it as a signpost to a potentially biased region of the early universe, as might be expected in hierarchical structure formation models. Imaging to the confusion limit with the innovative, wide-field submillimeter bolometer camera, SCUBA-2, we are sensitive to colder and/or less luminous galaxies in the surroundings of HFLS3. We use the Millennium Simulation to illustrate that HFLS3 may be expected to have companions if it is as massive as claimed, but find no significant evidence from the surface density of SCUBA-2 galaxies in its vicinity, or their colors, that HFLS3 marks an overdensity of dusty, star-forming galaxies. We cannot rule out the presence of dusty neighbors with confidence, but deeper 450 μm imaging has the potential to more tightly constrain the redshifts of nearby galaxies, at least one of which likely lies at z ≳ 5. If associations with HFLS3 can be ruled out, this could be taken as evidence that HFLS3 is less biased than a simple extrapolation of the Millennium Simulation may imply. This could suggest either that it represents a rare short-lived, but highly luminous, phase in the evolution of an otherwise typical galaxy, or that this system has suffered amplification due to a foreground gravitational lens and so is not as intrinsically luminous as claimed.

  18. HerMES: Spectral energy distributions of submillimeter galaxies at z > 4

    International Nuclear Information System (INIS)

    Huang, J.-S.; Rigopoulou, D.; Magdis, G.; Rowan-Robinson, M.; Clements, D. L.; Dai, Y.; Fazio, G. G.; Bock, J. J.; Burgarella, D.; Chapman, S.; Cooray, A.; Farrah, D.; Glenn, J.; Oliver, S.; Smith, A. J.; Wang, L.; Page, M.; Symeonidis, M.; Riechers, D.; Roseboom, I.

    2014-01-01

    We present a study of the infrared properties for a sample of seven spectroscopically confirmed submillimeter galaxies (SMGs) at z > 4.0. By combining ground-based near-infrared, Spitzer IRAC and MIPS, Herschel SPIRE, and ground-based submillimeter/millimeter photometry, we construct their spectral energy distributions (SEDs) and a composite model to fit the SEDs. The model includes a stellar emission component at λ rest < 3.5 μm, a hot dust component peaking at λ rest ∼ 5 μm, and cold dust component which becomes significant for λ rest > 50 μm. Six objects in the sample are detected at 250 and 350 μm. The dust temperatures for the sources in this sample are in the range of 40-80 K, and their L FIR ∼ 10 13 L ☉ qualifies them as hyper-luminous infrared galaxies. The mean FIR-radio index for this sample is around (q) = 2.2 indicating no radio excess in their radio emission. Most sources in the sample have 24 μm detections corresponding to a rest-frame 4.5 μm luminosity of Log 10 (L 4.5 /L ☉ ) = 11 ∼ 11.5. Their L 4.5 /L FIR ratios are very similar to those of starburst-dominated SMGs at z ∼ 2. The L CO – L FIR relation for this sample is consistent with that determined for local ULIRGs and SMGs at z ∼ 2. We conclude that SMGs at z > 4 are hotter and more luminous in the FIR but otherwise very similar to those at z ∼ 2. None of these sources show any sign of the strong QSO phase being triggered.

  19. An ALMA survey of submillimeter galaxies in the extended Chandra deep field south: The redshift distribution and evolution of submillimeter galaxies

    International Nuclear Information System (INIS)

    Simpson, J. M.; Swinbank, A. M.; Smail, Ian; Alexander, D. M.; Danielson, A. L. R.; Thomson, A. P.; Brandt, W. N.; Bertoldi, F.; Karim, A.; De Breuck, C.; Chapman, S. C.; Coppin, K. E. K.; Da Cunha, E.; Hodge, J. A.; Schinnerer, E.; Dannerbauer, H.; Greve, T. R.; Ivison, R. J.; Knudsen, K. K.; Poggianti, B. M.

    2014-01-01

    We present the first photometric redshift distribution for a large sample of 870 μm submillimeter galaxies (SMGs) with robust identifications based on observations with ALMA. In our analysis we consider 96 SMGs in the Extended Chandra Deep Field South, 77 of which have 4-19 band photometry. We model the SEDs for these 77 SMGs, deriving a median photometric redshift of z phot = 2.3 ± 0.1. The remaining 19 SMGs have insufficient photometry to derive photometric redshifts, but a stacking analysis of Herschel observations confirms they are not spurious. Assuming that these SMGs have an absolute H-band magnitude distribution comparable to that of a complete sample of z ∼ 1-2 SMGs, we demonstrate that they lie at slightly higher redshifts, raising the median redshift for SMGs to z phot = 2.5 ± 0.2. Critically we show that the proportion of galaxies undergoing an SMG-like phase at z ≥ 3 is at most 35% ± 5% of the total population. We derive a median stellar mass of M * = (8 ± 1) × 10 10 M ☉ , although there are systematic uncertainties of up to 5 × for individual sources. Assuming that the star formation activity in SMGs has a timescale of ∼100 Myr, we show that their descendants at z ∼ 0 would have a space density and M H distribution that are in good agreement with those of local ellipticals. In addition, the inferred mass-weighted ages of the local ellipticals broadly agree with the look-back times of the SMG events. Taken together, these results are consistent with a simple model that identifies SMGs as events that form most of the stars seen in the majority of luminous elliptical galaxies at the present day.

  20. An ALMA survey of submillimeter galaxies in the extended Chandra deep field south: The redshift distribution and evolution of submillimeter galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, J. M.; Swinbank, A. M.; Smail, Ian; Alexander, D. M.; Danielson, A. L. R.; Thomson, A. P. [Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Brandt, W. N. [Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802 (United States); Bertoldi, F.; Karim, A. [Argelander-Institute for Astronomy, Bonn University, Auf dem Hügel 71, D-53121 Bonn (Germany); De Breuck, C. [European Southern Observatory, Karl-Schwarzschild Straße, D-85748 Garching bei München (Germany); Chapman, S. C. [Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS B3H 3J5 (Canada); Coppin, K. E. K. [Centre for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Da Cunha, E.; Hodge, J. A.; Schinnerer, E. [Max-Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Dannerbauer, H. [Universität Wien, Institut für Astrophysik, Türkenschanzstraße 17, A-1180 Wien (Austria); Greve, T. R. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Ivison, R. J. [Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Knudsen, K. K. [Department of Earth and Space Science, Onsala Space Observatory, Chalmers University of Technology, SE-43992 Onsala (Sweden); Poggianti, B. M., E-mail: j.m.simpson@dur.ac.uk [INAF-Astronomical Observatory of Padova, I-35122 Padova (Italy); and others

    2014-06-20

    We present the first photometric redshift distribution for a large sample of 870 μm submillimeter galaxies (SMGs) with robust identifications based on observations with ALMA. In our analysis we consider 96 SMGs in the Extended Chandra Deep Field South, 77 of which have 4-19 band photometry. We model the SEDs for these 77 SMGs, deriving a median photometric redshift of z {sub phot} = 2.3 ± 0.1. The remaining 19 SMGs have insufficient photometry to derive photometric redshifts, but a stacking analysis of Herschel observations confirms they are not spurious. Assuming that these SMGs have an absolute H-band magnitude distribution comparable to that of a complete sample of z ∼ 1-2 SMGs, we demonstrate that they lie at slightly higher redshifts, raising the median redshift for SMGs to z {sub phot} = 2.5 ± 0.2. Critically we show that the proportion of galaxies undergoing an SMG-like phase at z ≥ 3 is at most 35% ± 5% of the total population. We derive a median stellar mass of M {sub *} = (8 ± 1) × 10{sup 10} M {sub ☉}, although there are systematic uncertainties of up to 5 × for individual sources. Assuming that the star formation activity in SMGs has a timescale of ∼100 Myr, we show that their descendants at z ∼ 0 would have a space density and M{sub H} distribution that are in good agreement with those of local ellipticals. In addition, the inferred mass-weighted ages of the local ellipticals broadly agree with the look-back times of the SMG events. Taken together, these results are consistent with a simple model that identifies SMGs as events that form most of the stars seen in the majority of luminous elliptical galaxies at the present day.

  1. Recent progress in photoactive organic field-effect transistors.

    Science.gov (United States)

    Wakayama, Yutaka; Hayakawa, Ryoma; Seo, Hoon-Seok

    2014-04-01

    Recent progress in photoactive organic field-effect transistors (OFETs) is reviewed. Photoactive OFETs are divided into light-emitting (LE) and light-receiving (LR) OFETs. In the first part, LE-OFETs are reviewed from the viewpoint of the evolution of device structures. Device performances have improved in the last decade with the evolution of device structures from single-layer unipolar to multi-layer ambipolar transistors. In the second part, various kinds of LR-OFETs are featured. These are categorized according to their functionalities: phototransistors, non-volatile optical memories, and photochromism-based transistors. For both, various device configurations are introduced: thin-film based transistors for practical applications, single-crystalline transistors to investigate fundamental physics, nanowires, multi-layers, and vertical transistors based on new concepts.

  2. Recent progress in photoactive organic field-effect transistors

    International Nuclear Information System (INIS)

    Wakayama, Yutaka; Hayakawa, Ryoma; Seo, Hoon-Seok

    2014-01-01

    Recent progress in photoactive organic field-effect transistors (OFETs) is reviewed. Photoactive OFETs are divided into light-emitting (LE) and light-receiving (LR) OFETs. In the first part, LE-OFETs are reviewed from the viewpoint of the evolution of device structures. Device performances have improved in the last decade with the evolution of device structures from single-layer unipolar to multi-layer ambipolar transistors. In the second part, various kinds of LR-OFETs are featured. These are categorized according to their functionalities: phototransistors, non-volatile optical memories, and photochromism-based transistors. For both, various device configurations are introduced: thin-film based transistors for practical applications, single-crystalline transistors to investigate fundamental physics, nanowires, multi-layers, and vertical transistors based on new concepts. (review)

  3. Organic Thin-Film Transistor (OTFT-Based Sensors

    Directory of Open Access Journals (Sweden)

    Daniel Elkington

    2014-04-01

    Full Text Available Organic thin film transistors have been a popular research topic in recent decades and have found applications from flexible displays to disposable sensors. In this review, we present an overview of some notable articles reporting sensing applications for organic transistors with a focus on the most recent publications. In particular, we concentrate on three main types of organic transistor-based sensors: biosensors, pressure sensors and “e-nose”/vapour sensors.

  4. Electrical pulse burnout of transistors in intense ionizing radiation

    International Nuclear Information System (INIS)

    Hartman, E.F.; Evans, D.C.

    1975-01-01

    Tests examining possible synergistic effects of electrical pulses and ionizing radiation on transistors were performed and energy/power thresholds for transistor burnout determined. The effect of ionizing radiation on burnout thresholds was found to be minimal, indicating that electrical pulse testing in the absence of radiation produces burnout-threshold results which are applicable to IEMP studies. The conditions of ionized transistor junctions and radiation induced current surges at semiconductor device terminals are inherent in IEMP studies of electrical circuits

  5. Application of the Johnson criteria to graphene transistors

    International Nuclear Information System (INIS)

    Kelly, M J

    2013-01-01

    For 60 years, the Johnson criteria have guided the development of materials and the materials choices for field-effect and bipolar transistor technology. Intrinsic graphene is a semi-metal, precluding transistor applications, but only under lateral bias is a gap opened and transistor action possible. This first application of the Johnson criteria to biased graphene suggests that this material will struggle to ever achieve competitive commercial applications. (fast track communication)

  6. Benchmarking organic mixed conductors for transistors

    KAUST Repository

    Inal, Sahika; Malliaras, George G.; Rivnay, Jonathan

    2017-01-01

    Organic mixed conductors have garnered significant attention in applications from bioelectronics to energy storage/generation. Their implementation in organic transistors has led to enhanced biosensing, neuromorphic function, and specialized circuits. While a narrow class of conducting polymers continues to excel in these new applications, materials design efforts have accelerated as researchers target new functionality, processability, and improved performance/stability. Materials for organic electrochemical transistors (OECTs) require both efficient electronic transport and facile ion injection in order to sustain high capacity. In this work, we show that the product of the electronic mobility and volumetric charge storage capacity (µC*) is the materials/system figure of merit; we use this framework to benchmark and compare the steady-state OECT performance of ten previously reported materials. This product can be independently verified and decoupled to guide materials design and processing. OECTs can therefore be used as a tool for understanding and designing new organic mixed conductors.

  7. Benchmarking organic mixed conductors for transistors

    KAUST Repository

    Inal, Sahika

    2017-11-20

    Organic mixed conductors have garnered significant attention in applications from bioelectronics to energy storage/generation. Their implementation in organic transistors has led to enhanced biosensing, neuromorphic function, and specialized circuits. While a narrow class of conducting polymers continues to excel in these new applications, materials design efforts have accelerated as researchers target new functionality, processability, and improved performance/stability. Materials for organic electrochemical transistors (OECTs) require both efficient electronic transport and facile ion injection in order to sustain high capacity. In this work, we show that the product of the electronic mobility and volumetric charge storage capacity (µC*) is the materials/system figure of merit; we use this framework to benchmark and compare the steady-state OECT performance of ten previously reported materials. This product can be independently verified and decoupled to guide materials design and processing. OECTs can therefore be used as a tool for understanding and designing new organic mixed conductors.

  8. Cylindrical-shaped nanotube field effect transistor

    KAUST Repository

    Hussain, Muhammad Mustafa

    2015-12-29

    A cylindrical-shaped nanotube FET may be manufactured on silicon (Si) substrates as a ring etched into a gate stack and filled with semiconductor material. An inner gate electrode couples to a region of the gate stack inside the inner circumference of the ring. An outer gate electrode couples to a region of the gate stack outside the outer circumference of the ring. The multi-gate cylindrical-shaped nanotube FET operates in volume inversion for ring widths below 15 nanometers. The cylindrical-shaped nanotube FET demonstrates better short channel effect (SCE) mitigation and higher performance (I.sub.on/I.sub.off) than conventional transistor devices. The cylindrical-shaped nanotube FET may also be manufactured with higher yields and cheaper costs than conventional transistors.

  9. Cylindrical-shaped nanotube field effect transistor

    KAUST Repository

    Hussain, Muhammad Mustafa; Fahad, Hossain M.; Smith, Casey E.; Rojas, Jhonathan Prieto

    2015-01-01

    A cylindrical-shaped nanotube FET may be manufactured on silicon (Si) substrates as a ring etched into a gate stack and filled with semiconductor material. An inner gate electrode couples to a region of the gate stack inside the inner circumference of the ring. An outer gate electrode couples to a region of the gate stack outside the outer circumference of the ring. The multi-gate cylindrical-shaped nanotube FET operates in volume inversion for ring widths below 15 nanometers. The cylindrical-shaped nanotube FET demonstrates better short channel effect (SCE) mitigation and higher performance (I.sub.on/I.sub.off) than conventional transistor devices. The cylindrical-shaped nanotube FET may also be manufactured with higher yields and cheaper costs than conventional transistors.

  10. Nanowire field effect transistors principles and applications

    CERN Document Server

    Jeong, Yoon-Ha

    2014-01-01

    “Nanowire Field Effect Transistor: Basic Principles and Applications” places an emphasis on the application aspects of nanowire field effect transistors (NWFET). Device physics and electronics are discussed in a compact manner, together with the p-n junction diode and MOSFET, the former as an essential element in NWFET and the latter as a general background of the FET. During this discussion, the photo-diode, solar cell, LED, LD, DRAM, flash EEPROM and sensors are highlighted to pave the way for similar applications of NWFET. Modeling is discussed in close analogy and comparison with MOSFETs. Contributors focus on processing, electrostatic discharge (ESD) and application of NWFET. This includes coverage of solar and memory cells, biological and chemical sensors, displays and atomic scale light emitting diodes. Appropriate for scientists and engineers interested in acquiring a working knowledge of NWFET as well as graduate students specializing in this subject.

  11. Celebrating 65th Anniversary of the Transistor

    Directory of Open Access Journals (Sweden)

    Goce L. Arsov

    2013-12-01

    Full Text Available The paper is dedicated to the 65th anniversary of the invention of the revolutionary electronic component that actually changed our way of life—the transistor. It recounts the key historical moments leading up to the invention of the first semiconductor active component in 1947. The meaning of the blend “transistor” is explained using the memorandum issued by Bell Telephone Laboratories. Certain problems appeared in the engineering phase of the transistor development and the new components obtained as a result of this research are reviewed. The impact of this invention on the development of power electronics is being emphasized. Finally, the possibility that the most important invention of the 20th century has been conceived not once but twice is discussed.

  12. Hybrid light emitting transistors (Presentation Recording)

    Science.gov (United States)

    Muhieddine, Khalid; Ullah, Mujeeb; Namdas, Ebinazar B.; Burn, Paul L.

    2015-10-01

    Organic light-emitting diodes (OLEDs) are well studied and established in current display applications. Light-emitting transistors (LETs) have been developed to further simplify the necessary circuitry for these applications, combining the switching capabilities of a transistor with the light emitting capabilities of an OLED. Such devices have been studied using mono- and bilayer geometries and a variety of polymers [1], small organic molecules [2] and single crystals [3] within the active layers. Current devices can often suffer from low carrier mobilities and most operate in p-type mode due to a lack of suitable n-type organic charge carrier materials. Hybrid light-emitting transistors (HLETs) are a logical step to improve device performance by harnessing the charge carrier capabilities of inorganic semiconductors [4]. We present state of the art, all solution processed hybrid light-emitting transistors using a non-planar contact geometry [1, 5]. We will discuss HLETs comprised of an inorganic electron transport layer prepared from a sol-gel of zinc tin oxide and several organic emissive materials. The mobility of the devices is found between 1-5 cm2/Vs and they had on/off ratios of ~105. Combined with optical brightness and efficiencies of the order of 103 cd/m2 and 10-3-10-1 %, respectively, these devices are moving towards the performance required for application in displays. [1] M. Ullah, K. Tandy, S. D. Yambem, M. Aljada, P. L. Burn, P. Meredith, E. B. Namdas., Adv. Mater. 2013, 25, 53, 6213 [2] R. Capelli, S. Toffanin, G. Generali, H. Usta, A. Facchetti, M. Muccini, Nature Materials 2010, 9, 496 [3] T. Takenobu, S. Z. Bisri, T. Takahashi, M. Yahiro, C. Adachi, Y. Iwasa, Phys. Rev. Lett. 2008, 100, 066601 [4] H. Nakanotani, M. Yahiro, C. Adachi, K. Yano, Appl. Phys. Lett. 2007, 90, 262104 [5] K. Muhieddine, M. Ullah, B. N. Pal, P. Burn E. B. Namdas, Adv. Mater. 2014, 26,37, 6410

  13. Assessment of Phospohrene Field Effect Transistors

    Science.gov (United States)

    2018-01-28

    majoring in electrical engineering were trained through the project. During the project period, one graduated with an MS degree, while another one...34Phosphorene FETs-Promising Transistors Based on a few Layers of Phosphorus Atoms," Chinese Academy of Engineering , Chengdu, China, Jul. 2015. J.C. M. Hwang... Nanotechnology , Arlington, VA, Oct.2015. J. C. M. Hwang, "Surface Passivation and RF Characterization of Phosphorene FETs," Air Force Research Lab, Dayton

  14. BUSFET -- A radiation-hardened SOI transistor

    International Nuclear Information System (INIS)

    Schwank, J.R.; Shaneyfelt, M.R.; Draper, B.L.; Dodd, P.E.

    1999-01-01

    The total-dose hardness of SOI technology is limited by radiation-induced charge trapping in gate, field, and SOI buried oxides. Charge trapping in the buried oxide can lead to back-channel leakage and makes hardening SOI transistors more challenging than hardening bulk-silicon transistors. Two avenues for hardening the back-channel are (1) to use specially prepared SOI buried oxides that reduce the net amount of trapped positive charge or (2) to design transistors that are less sensitive to the effects of trapped charge in the buried oxide. In this work, the authors propose a partially-depleted SOI transistor structure for mitigating the effects of trapped charge in the buried oxide on radiation hardness. They call this structure the BUSFET--Body Under Source FET. The BUSFET utilizes a shallow source and a deep drain. As a result, the silicon depletion region at the back channel caused by radiation-induced charge trapping in the buried oxide does not form a conducting path between source and drain. Thus, the BUSFET structure design can significantly reduce radiation-induced back-channel leakage without using specially prepared buried oxides. Total dose hardness is achieved without degrading the intrinsic SEU or dose rate hardness of SOI technology. The effectiveness of the BUSFET structure for reducing total-dose back-channel leakage depends on several variables, including the top silicon film thickness and doping concentration, and the depth of the source. 3-D simulations show that for a body doping concentration of 10 18 cm -3 , a drain bias of 3 V, and a source depth of 90 nm, a silicon film thickness of 180 nm is sufficient to almost completely eliminate radiation-induced back-channel leakage. However, for a doping concentration of 3 x 10 17 cm -3 , a thicker silicon film (300 nm) must be used

  15. Third International Kharkov Symposium "Physics and Engineering of Millimeter and Submillimeter Waves" MSMW󈨦 Symposium Proceedings, Volume 1,

    Science.gov (United States)

    1998-09-01

    Europ . Microwave Conf. Proceedings" (Sept., 5-8,1994, Cannes, France), 1994, v. 1, pp. 431-436. MSMW󈨦 Symposium Proceedings. Kharkov, Ukraine...atmospheric fronts and storm zones. The SLRs can equally be utilized to record extra-topical and tropical cyclones (hurricanes, typhoons) which are exceed...application of the SLRs to monitor extratropic ?’ cyclones known to seriously affect the weather conditions across the vast ex- panses of any country

  16. Uniformity of fully gravure printed organic field-effect transistors

    International Nuclear Information System (INIS)

    Hambsch, M.; Reuter, K.; Stanel, M.; Schmidt, G.; Kempa, H.; Fuegmann, U.; Hahn, U.; Huebler, A.C.

    2010-01-01

    Fully mass-printed organic field-effect transistors were made completely by means of gravure printing. Therefore a special printing layout was developed in order to avoid register problems in print direction. Upon using this layout, contact pads for source-drain electrodes of the transistors are printed together with the gate electrodes in one and the same printing run. More than 50,000 transistors have been produced and by random tests a yield of approximately 75% has been determined. The principle suitability of the gravure printed transistors for integrated circuits has been shown by the realization of ring oscillators.

  17. Deformable Organic Nanowire Field-Effect Transistors.

    Science.gov (United States)

    Lee, Yeongjun; Oh, Jin Young; Kim, Taeho Roy; Gu, Xiaodan; Kim, Yeongin; Wang, Ging-Ji Nathan; Wu, Hung-Chin; Pfattner, Raphael; To, John W F; Katsumata, Toru; Son, Donghee; Kang, Jiheong; Matthews, James R; Niu, Weijun; He, Mingqian; Sinclair, Robert; Cui, Yi; Tok, Jeffery B-H; Lee, Tae-Woo; Bao, Zhenan

    2018-02-01

    Deformable electronic devices that are impervious to mechanical influence when mounted on surfaces of dynamically changing soft matters have great potential for next-generation implantable bioelectronic devices. Here, deformable field-effect transistors (FETs) composed of single organic nanowires (NWs) as the semiconductor are presented. The NWs are composed of fused thiophene diketopyrrolopyrrole based polymer semiconductor and high-molecular-weight polyethylene oxide as both the molecular binder and deformability enhancer. The obtained transistors show high field-effect mobility >8 cm 2 V -1 s -1 with poly(vinylidenefluoride-co-trifluoroethylene) polymer dielectric and can easily be deformed by applied strains (both 100% tensile and compressive strains). The electrical reliability and mechanical durability of the NWs can be significantly enhanced by forming serpentine-like structures of the NWs. Remarkably, the fully deformable NW FETs withstand 3D volume changes (>1700% and reverting back to original state) of a rubber balloon with constant current output, on the surface of which it is attached. The deformable transistors can robustly operate without noticeable degradation on a mechanically dynamic soft matter surface, e.g., a pulsating balloon (pulse rate: 40 min -1 (0.67 Hz) and 40% volume expansion) that mimics a beating heart, which underscores its potential for future biomedical applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. The next generation balloon-borne large aperture submillimeter telescope (BLAST-TNG)

    Science.gov (United States)

    Dober, Bradley Jerald

    Large areas of astrophysics, such as precision cosmology, have benefited greatly from large maps and datasets, yielded by telescopes of ever-increasing number and ability. However, due to the unique challenges posed by submillimeter polarimetry, the study of molecular cloud dynamics and star formation remain stunted. Previously, polarimetry data was limited to a few vectors on only the brightest areas of molecular clouds. This made drawing statistically-driven conclusions a daunting task. However, the successful flight of the Balloon-born Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol) generated maps with thousands of independent polarization measurements of molecular clouds, and ushered in a new era of empirical modeling of molecular cloud dynamics. Now that the potential benefits from large-scale maps of magnetic fields in molecular clouds had been identified, a successor that would truly unlock the secrets must be born. The Next Generation Balloon-borne Large Aperture Submillimeter Telescope (BLAST-TNG), the successor to BLASTPol, has the ability to make larger and more detailed maps of magnetic fields in molecular clouds. It will push the field of star formation into a statistics-driven, empirical realm. With these large, detailed datasets, astronomers will be able to find new relationships between the dust dynamics and the magnetic fields. The field will surge to a new level of understanding. One of the key enabling technologies of BLAST-TNG is its three arrays of polarization-sensitive Microwave Kinetic Inductance Detectors (MKIDs). MKIDs are superconducting RLC circuits with a resonant frequency that shifts proportionally to the amount of incident radiation. The key feature of MKIDs is that thousands of detectors, each with their own unique resonant frequency, can be coupled to the same readout line. This technology will be able to drive the production of large-scale monolithic arrays, containing tens or hundreds of thousands of detectors

  19. The Overdense Environments of WISE-Selected, Ultra-Luminous, High-Redshift AGN in the Submillimeter

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Suzy F., E-mail: suzy.jones@chalmers.se [Department of Space, Earth, and Environment, Chalmers University of Technology, Onsala Space Observatory, Onsala (Sweden)

    2017-11-21

    The environments around WISE-selected hot dust obscured galaxies (Hot DOGs) and WISE/radio-selected active galactic nuclei (AGNs) at average redshifts of z = 2.7 and z = 1.7, respectively, were found to have overdensities of companion Submillimeter-selected sources. The overdensities were of ~2–3 and ~5–6, respectively, compared with blank field submm surveys. The space densities in both samples were found to be overdense compared to normal star-forming galaxies and Submillimeter galaxies (SMGs). All of the companion sources have consistent mid-IR colors and mid-IR to submm ratios to SMGs. Monte Carlo simulations show no angular correlation, which could indicate protoclusters on scales larger than the SCUBA-2 1.5 arcmin scale maps. WISE-selected AGNs appear to be good indicators of overdense areas of active galaxies at high redshift.

  20. Submillimeter residual losses in high-Tc superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Miller, David [Univ. of California, Berkeley, CA (United States)

    1993-09-01

    Bolometry was used obtain accurate submillimeter residual loss data for epitaxial films of YBa2Cu3O7 (YBCO), Tl2Ca2Ba2Cu3O10, Tl2CaBa2Cu2O8 (TCBCO), and Ba0.6K0.4BiO3 (BKBO). We were able to fit the absorptivity measured for Nb films to an Eliashberg strong coupling calculation; excellent agreement resulted between parameters from best fits and measured Residual Resistivity Ratio. Microwave surface resistance measurements made on the same YBCO and TCBCO films are in excellent agreement with submillimeter measurements. Absorptivities for all YBCO films studied are qualitatively similar, increasing smoothly with frequency, with no gap-like features below the well known absorption edge at 450 cm-1. Losses in YBCO films were fit to a weakly coupled grain model for the a-b plane conductivity. Strong phonon structure was observed in TCBCO films between 60 and 700 cm-1 (2 THz and 23 THz); these losses could not be fitted to the simple weakly coupled grain model, in contrast to the case for other high-Tc superconductors where phonon structure observed in ceramics are is absent in epitaxial oriented films and crystals because of electronic screening due to high conductivity of a-b planes. Absorptivity data for the BKBO films all show a strong absorption onset near the BCS tunneling gap of 3.5 kBTc. Comparison with strong coupling Eliashberg predictions and of a Kramers-Kronig analysis indicate that the absorption onset is consistent with a superconducting energy gap. Effects of magnetic field on residual losses in YBCO films show a resonant absorption feature in vicinity of predicted

  1. A COMPREHENSIVE VIEW OF A STRONGLY LENSED PLANCK-ASSOCIATED SUBMILLIMETER GALAXY

    Energy Technology Data Exchange (ETDEWEB)

    Fu Hai; Cooray, A. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Jullo, E. [Observatoire d' Astrophysique de Marseille-Provence, 38 rue Frederic Joliot-Curie, F-13388 Marseille (France); Bussmann, R. S. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Ivison, R. J. [UK Astronomy Technology Centre, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom); Perez-Fournon, I. [Instituto de Astrofisica de Canarias (IAC), E-38200 La Laguna, Tenerife (Spain); Djorgovski, S. G.; Scoville, N.; Yan, L.; Riechers, D. A.; Bradford, M. [Department of Astronomy, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Aguirre, J. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States); Auld, R. [School of Physics and Astronomy, Cardiff University, The Parade, Cardiff CF24 3AA (United Kingdom); Baes, M. [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, B-9000 Gent (Belgium); Baker, A. J. [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Rd., Piscataway, NJ 08854 (United States); Cava, A. [Departamento de Astrofisica, Facultad de CC. Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Clements, D. L. [Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom); Dannerbauer, H. [Institut fuer Astronomie, Universitaet Wien, Tuerkenschanzstrasse 17, A-1160 Wien (Austria); Dariush, A. [Physics Department, Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom); De Zotti, G., E-mail: haif@uci.edu [INAF-Osservatorio Astronomico di Padova, Vicolo dell' Osservatorio 5, I-35122 Padova (Italy); and others

    2012-07-10

    We present high-resolution maps of stars, dust, and molecular gas in a strongly lensed submillimeter galaxy (SMG) at z = 3.259. HATLAS J114637.9-001132 is selected from the Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS) as a strong lens candidate mainly based on its unusually high 500 {mu}m flux density ({approx}300 mJy). It is the only high-redshift Planck detection in the 130 deg{sup 2} H-ATLAS Phase-I area. Keck Adaptive Optics images reveal a quadruply imaged galaxy in the K band while the Submillimeter Array and the Jansky Very Large Array show doubly imaged 880 {mu}m and CO(1{yields}0) sources, indicating differentiated distributions of the various components in the galaxy. In the source plane, the stars reside in three major kpc-scale clumps extended over {approx}1.6 kpc, the dust in a compact ({approx}1 kpc) region {approx}3 kpc north of the stars, and the cold molecular gas in an extended ({approx}7 kpc) disk {approx}5 kpc northeast of the stars. The emissions from the stars, dust, and gas are magnified by {approx}17, {approx}8, and {approx}7 times, respectively, by four lensing galaxies at z {approx} 1. Intrinsically, the lensed galaxy is a warm (T{sub dust} {approx} 40-65 K), hyper-luminous (L{sub IR} {approx} 1.7 Multiplication-Sign 10{sup 13} L{sub Sun }; star formation rate (SFR) {approx}2000 M{sub Sun} yr{sup -1}), gas-rich (M{sub gas}/M{sub baryon} {approx} 70%), young (M{sub stellar}/SFR {approx} 20 Myr), and short-lived (M{sub gas}/SFR {approx} 40 Myr) starburst. With physical properties similar to unlensed z > 2 SMGs, HATLAS J114637.9-001132 offers a detailed view of a typical SMG through a powerful cosmic microscope.

  2. A cusp electron gun for millimeter wave gyrodevices

    Science.gov (United States)

    Donaldson, C. R.; He, W.; Cross, A. W.; Li, F.; Phelps, A. D. R.; Zhang, L.; Ronald, K.; Robertson, C. W.; Whyte, C. G.; Young, A. R.

    2010-04-01

    The experimental results of a thermionic cusp electron gun, to drive millimeter and submillimeter wave harmonic gyrodevices, are reported in this paper. Using a "smooth" magnetic field reversal formed by two coils this gun generated an annular-shaped, axis-encircling electron beam with 1.5 A current, and an adjustable velocity ratio α of up to 1.56 at a beam voltage of 40 kV. The beam cross-sectional shape and transported beam current were measured by a witness plate technique and Faraday cup, respectively. These measured results were found to be in excellent agreement with the simulated results using the three-dimensional code MAGIC.

  3. Retrieval of an ice water path over the ocean from ISMAR and MARSS millimeter and submillimeter brightness temperatures

    Science.gov (United States)

    Brath, Manfred; Fox, Stuart; Eriksson, Patrick; Chawn Harlow, R.; Burgdorf, Martin; Buehler, Stefan A.

    2018-02-01

    A neural-network-based retrieval method to determine the snow ice water path (SIWP), liquid water path (LWP), and integrated water vapor (IWV) from millimeter and submillimeter brightness temperatures, measured by using airborne radiometers (ISMAR and MARSS), is presented. The neural networks were trained by using atmospheric profiles from the ICON numerical weather prediction (NWP) model and by radiative transfer simulations using the Atmospheric Radiative Transfer Simulator (ARTS). The basic performance of the retrieval method was analyzed in terms of offset (bias) and the median fractional error (MFE), and the benefit of using submillimeter channels was studied in comparison to pure microwave retrievals. The retrieval is offset-free for SIWP > 0.01 kg m-2, LWP > 0.1 kg m-2, and IWV > 3 kg m-2. The MFE of SIWP decreases from 100 % at SIWP = 0.01 kg m-2 to 20 % at SIWP = 1 kg m-2 and the MFE of LWP from 100 % at LWP = 0.05 kg m-2 to 30 % at LWP = 1 kg m-2. The MFE of IWV for IWV > 3 kg m-2 is 5 to 8 %. The SIWP retrieval strongly benefits from submillimeter channels, which reduce the MFE by a factor of 2, compared to pure microwave retrievals. The IWV and the LWP retrievals also benefit from submillimeter channels, albeit to a lesser degree. The retrieval was applied to ISMAR and MARSS brightness temperatures from FAAM flight B897 on 18 March 2015 of a precipitating frontal system west of the coast of Iceland. Considering the given uncertainties, the retrieval is in reasonable agreement with the SIWP, LWP, and IWV values simulated by the ICON NWP model for that flight. A comparison of the retrieved IWV with IWV from 12 dropsonde measurements shows an offset of 0.5 kg m-2 and an RMS difference of 0.8 kg m-2, showing that the retrieval of IWV is highly effective even under cloudy conditions.

  4. Dose enhancement effects of X ray radiation in bipolar transistors

    International Nuclear Information System (INIS)

    Chen Panxun

    1997-01-01

    The author has presented behaviour degradation and dose enhancement effects of bipolar transistors in X ray irradiation environment. The relative dose enhancement factors of X ray radiation were measured in bipolar transistors by the experiment methods. The mechanism of bipolar device dose enhancement was investigated

  5. Nanometer size field effect transistors for terahertz detectors

    International Nuclear Information System (INIS)

    Knap, W; Rumyantsev, S; Coquillat, D; Dyakonova, N; Teppe, F; Vitiello, M S; Tredicucci, A; Blin, S; Shur, M; Nagatsuma, T

    2013-01-01

    Nanometer size field effect transistors can operate as efficient resonant or broadband terahertz detectors, mixers, phase shifters and frequency multipliers at frequencies far beyond their fundamental cut-off frequency. This work is an overview of some recent results concerning the application of nanometer scale field effect transistors for the detection of terahertz radiation. (paper)

  6. The Smallest Transistor-Based Nonautonomous Chaotic Circuit

    DEFF Research Database (Denmark)

    Lindberg, Erik; Murali, K.; Tamasevicius, Arunas

    2005-01-01

    A nonautonomous chaotic circuit based on one transistor, two capacitors, and two resistors is described. The mechanism behind the chaotic performance is based on “disturbance of integration.” The forward part and the reverse part of the bipolar transistor are “fighting” about the charging...

  7. Method for double-sided processing of thin film transistors

    Science.gov (United States)

    Yuan, Hao-Chih; Wang, Guogong; Eriksson, Mark A.; Evans, Paul G.; Lagally, Max G.; Ma, Zhenqiang

    2008-04-08

    This invention provides methods for fabricating thin film electronic devices with both front- and backside processing capabilities. Using these methods, high temperature processing steps may be carried out during both frontside and backside processing. The methods are well-suited for fabricating back-gate and double-gate field effect transistors, double-sided bipolar transistors and 3D integrated circuits.

  8. Single-event burnout of epitaxial bipolar transistors

    Energy Technology Data Exchange (ETDEWEB)

    Kuboyama, S.; Sugimoto, K.; Shugyo, S.; Matsuda, S. [National Space Development Agency of Japan, Tsukuba, Ibaraki (Japan); Hirao, T. [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan)

    1998-12-01

    Single-Event Burnout (SEB) of bipolar junction transistors (BJTs) has been observed nondestructively. It was revealed that all the NPN BJTs, including small signal transistors, with thinner epitaxial layers were inherently susceptible to the SEB phenomenon. It was demonstrated that several design parameters of BJTs were responsible for SEB susceptibility. Additionally, destructive and nondestructive modes of SEB were identified.

  9. Single-event burnout of epitaxial bipolar transistors

    Energy Technology Data Exchange (ETDEWEB)

    Kuboyama, Satoshi; Sugimoto, Kenji; Matsuda, Sumio [National Space Development Agency of Japan, Ysukuba, Ibaraki (Japan); Hirao, Toshio

    1998-10-01

    Single-event burnout (SEB) of bipolar junction transistors (BJTs) has been observed nondestructively. It was revealed that all the NPN BJTs including small signal transistors with thinner epitaxial layer were inherently susceptible to the SEB phenomenon. It was demonstrated that several design parameters of BJTs were responsible for SEB susceptibility. Additionally, destructive and nondestructive modes of SEB were identified. (author)

  10. Outlook and Emerging Semiconducting Materials for Ambipolar Transistors

    NARCIS (Netherlands)

    Bisri, Satria Zulkarnaen; Piliego, Claudia; Gao, Jia; Loi, Maria Antonietta

    Ambipolar or bipolar transistors are transistors in which both holes and electrons are mobile inside the conducting channel. This device allows switching among several states: the hole-dominated on-state, the off-state, and the electron-dominated on-state. In the past year, it has attracted great

  11. Very High Frequency Two-Port Characterization of Transistors

    DEFF Research Database (Denmark)

    Hertel, Jens Christian; Nour, Yasser; Jørgensen, Ivan Harald Holger

    To properly use transistors in VHF converters, they need to be characterized under similar conditions. This research presents a two-port method, using a network analyzer (NWA) with a S-port setup. The method is a one-shot method, providing fast results of the off-state parasitics of the transistors....

  12. The Complete Semiconductor Transistor and Its Incomplete Forms

    International Nuclear Information System (INIS)

    Jie Binbin; Sah, C.-T.

    2009-01-01

    This paper describes the definition of the complete transistor. For semiconductor devices, the complete transistor is always bipolar, namely, its electrical characteristics contain both electron and hole currents controlled by their spatial charge distributions. Partially complete or incomplete transistors, via coined names or/and designed physical geometries, included the 1949 Shockley p/n junction transistor (later called Bipolar Junction Transistor, BJT), the 1952 Shockley unipolar 'field-effect' transistor (FET, later called the p/n Junction Gate FET or JGFET), as well as the field-effect transistors introduced by later investigators. Similarities between the surface-channel MOS-gate FET (MOSFET) and the volume-channel BJT are illustrated. The bipolar currents, identified by us in a recent nanometer FET with 2-MOS-gates on thin and nearly pure silicon base, led us to the recognition of the physical makeup and electrical current and charge compositions of a complete transistor and its extension to other three or more terminal signal processing devices, and also the importance of the terminal contacts.

  13. Doped organic transistors operating in the inversion and depletion regime

    Science.gov (United States)

    Lüssem, Björn; Tietze, Max L.; Kleemann, Hans; Hoßbach, Christoph; Bartha, Johann W.; Zakhidov, Alexander; Leo, Karl

    2013-01-01

    The inversion field-effect transistor is the basic device of modern microelectronics and is nowadays used more than a billion times on every state-of-the-art computer chip. In the future, this rigid technology will be complemented by flexible electronics produced at extremely low cost. Organic field-effect transistors have the potential to be the basic device for flexible electronics, but still need much improvement. In particular, despite more than 20 years of research, organic inversion mode transistors have not been reported so far. Here we discuss the first realization of organic inversion transistors and the optimization of organic depletion transistors by our organic doping technology. We show that the transistor parameters—in particular, the threshold voltage and the ON/OFF ratio—can be controlled by the doping concentration and the thickness of the transistor channel. Injection of minority carriers into the doped transistor channel is achieved by doped contacts, which allows forming an inversion layer. PMID:24225722

  14. Ambipolar charge transport in organic field-effect transistors

    NARCIS (Netherlands)

    Smits, E.C.P.; Anthopoulos, T.D.; Setayesh, S.; Veenendaal, van E.; Coehoorn, R.; Blom, P.W.M.; Boer, de B.; Leeuw, de D.M.

    2006-01-01

    A model describing charge transport in disordered ambipolar organic field-effect transistors is presented. The basis of this model is the variable-range hopping in an exponential density of states developed for disordered unipolar organic transistors. We show that the model can be used to calculate

  15. Circuit and method for controlling the threshold voltage of transistors.

    NARCIS (Netherlands)

    2008-01-01

    A control unit, for controlling a threshold voltage of a circuit unit having transistor devices, includes a reference circuit and a measuring unit. The measuring unit is configured to measure a threshold voltage of at least one sensing transistor of the circuit unit, and to measure a threshold

  16. On the 50th Anniversary of the Transistor

    DEFF Research Database (Denmark)

    Stassen, Flemming

    1997-01-01

    This paper celebrates the 50th anniversary of the invention of the bipolar transistor in 1947. Combined with the inventions of integration and planar technology, the invention of the transistor marks the beginning of a period of unprecedented growth, the industrialization of electronics....

  17. Fabrication of enhancement-mode AlGaN/GaN high electron mobility transistors using double plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Jong-Won, E-mail: jwlim@etri.re.kr [Photonic/Wireless Convergence Components Dept., IT Materials and Components Lab., Electronics and Telecommunications Research Institute, Daejeon 305-700 (Korea, Republic of); Ahn, Ho-Kyun; Kim, Seong-il; Kang, Dong-Min; Lee, Jong-Min; Min, Byoung-Gue; Lee, Sang-Heung; Yoon, Hyung-Sup; Ju, Chull-Won; Kim, Haecheon; Mun, Jae-Kyoung; Nam, Eun-Soo [Photonic/Wireless Convergence Components Dept., IT Materials and Components Lab., Electronics and Telecommunications Research Institute, Daejeon 305-700 (Korea, Republic of); Park, Hyung-Moo [Photonic/Wireless Convergence Components Dept., IT Materials and Components Lab., Electronics and Telecommunications Research Institute, Daejeon 305-700 (Korea, Republic of); Division of Electronics and Electrical Engineering, Dongguk University, Seoul (Korea, Republic of)

    2013-11-29

    We report the fabrication and DC and microwave characteristics of 0.5 μm AlGaN/GaN high electron mobility transistors using double plasma treatment process. Silicon nitride layers 700 and 150 Å thick were deposited by plasma-enhanced chemical vapor deposition at 260 °C to protect the device and to define the gate footprint. The double plasma process was carried out by two different etching techniques to obtain enhancement-mode AlGaN/GaN high electron mobility transistors with 0.5 μm gate lengths. The enhancement-mode AlGaN/GaN high electron mobility transistor was prepared in parallel to the depletion-mode AlGaN/GaN high electron mobility transistor device on one wafer. Completed double plasma treated 0.5 μm AlGaN/GaN high electron mobility transistor devices fabricated by dry etching exhibited a peak transconductance, gm, of 330 mS/mm, a breakdown voltage of 115 V, a current-gain cutoff frequency (f{sub T}) of 18 GHz, and a maximum oscillation frequency (f{sub max}) of 66 GHz. - Highlights: • The double plasma process was carried out by two different etching techniques. • Double plasma treated device exhibited a transconductance of 330 mS/mm. • Completed 0.5 μm gate device exhibited a current-gain cutoff frequency of 18 GHz. • The off-state breakdown voltage of 115 V for 0.5 μm gate device was obtained. • Continuous-wave output power density of 4.3 W/mm was obtained at 2.4 GHz.

  18. Fabrication of enhancement-mode AlGaN/GaN high electron mobility transistors using double plasma treatment

    International Nuclear Information System (INIS)

    Lim, Jong-Won; Ahn, Ho-Kyun; Kim, Seong-il; Kang, Dong-Min; Lee, Jong-Min; Min, Byoung-Gue; Lee, Sang-Heung; Yoon, Hyung-Sup; Ju, Chull-Won; Kim, Haecheon; Mun, Jae-Kyoung; Nam, Eun-Soo; Park, Hyung-Moo

    2013-01-01

    We report the fabrication and DC and microwave characteristics of 0.5 μm AlGaN/GaN high electron mobility transistors using double plasma treatment process. Silicon nitride layers 700 and 150 Å thick were deposited by plasma-enhanced chemical vapor deposition at 260 °C to protect the device and to define the gate footprint. The double plasma process was carried out by two different etching techniques to obtain enhancement-mode AlGaN/GaN high electron mobility transistors with 0.5 μm gate lengths. The enhancement-mode AlGaN/GaN high electron mobility transistor was prepared in parallel to the depletion-mode AlGaN/GaN high electron mobility transistor device on one wafer. Completed double plasma treated 0.5 μm AlGaN/GaN high electron mobility transistor devices fabricated by dry etching exhibited a peak transconductance, gm, of 330 mS/mm, a breakdown voltage of 115 V, a current-gain cutoff frequency (f T ) of 18 GHz, and a maximum oscillation frequency (f max ) of 66 GHz. - Highlights: • The double plasma process was carried out by two different etching techniques. • Double plasma treated device exhibited a transconductance of 330 mS/mm. • Completed 0.5 μm gate device exhibited a current-gain cutoff frequency of 18 GHz. • The off-state breakdown voltage of 115 V for 0.5 μm gate device was obtained. • Continuous-wave output power density of 4.3 W/mm was obtained at 2.4 GHz

  19. Simulation of a spintronic transistor: A study of its performance

    International Nuclear Information System (INIS)

    Pela, R.R.; Teles, L.K.

    2009-01-01

    We study theoretically the magnetic bipolar transistor, and compare its performance with common bipolar transistor. We present not only the simulation results for the characteristic curves, but also other relevant parameters related with its performance, such as: the current amplification factor, the open-loop gain, the hybrid parameters and the cutoff frequency. We noted that the spin-charge coupling introduces new phenomena that enrich the functionality characteristics of the magnetic bipolar transistor. Among other things, it has an adjustable band structure, which may be modified during the device operation; it exhibits the already known spin-voltaic effect. On the other hand, we observed that it is necessary a large g-factor to analyze the influence of the field B over the transistor. Nevertheless, we consider the magnetic bipolar transistor as a promising device for spintronic applications

  20. A spiking neuron circuit based on a carbon nanotube transistor

    International Nuclear Information System (INIS)

    Chen, C-L; Kim, K; Truong, Q; Shen, A; Li, Z; Chen, Y

    2012-01-01

    A spiking neuron circuit based on a carbon nanotube (CNT) transistor is presented in this paper. The spiking neuron circuit has a crossbar architecture in which the transistor gates are connected to its row electrodes and the transistor sources are connected to its column electrodes. An electrochemical cell is incorporated in the gate of the transistor by sandwiching a hydrogen-doped poly(ethylene glycol)methyl ether (PEG) electrolyte between the CNT channel and the top gate electrode. An input spike applied to the gate triggers a dynamic drift of the hydrogen ions in the PEG electrolyte, resulting in a post-synaptic current (PSC) through the CNT channel. Spikes input into the rows trigger PSCs through multiple CNT transistors, and PSCs cumulate in the columns and integrate into a ‘soma’ circuit to trigger output spikes based on an integrate-and-fire mechanism. The spiking neuron circuit can potentially emulate biological neuron networks and their intelligent functions. (paper)

  1. Theory and application of dual-transistor charge separation analysis

    International Nuclear Information System (INIS)

    Fleetwood, D.M.; Schwank, J.R.; Winokur, P.S.; Sexton, F.W.; Shaneyfelt, M.R.

    1989-01-01

    The authors describe a dual-transistor charge separation method to evaluate the radiation response of MOS transistors. This method requires that n- and p-channel transistors with identically processed oxides be irradiated under identical conditions at the same oxide electric fields. Combining features of single-transistor midgap and mobility methods, the authors show how one may determine threshold voltage shifts due to oxide-trapped and interface-trapped charge from standard threshold voltage and mobility measurements. These measurements can be made at currents 2-5 orders of magnitude higher than those required for midgap, subthreshold slope, and charge-pumping methods. The dual-transistor method contains no adjustable parameters, and includes an internal self-consistency check. The accuracy of the method is verified by comparison to midgap, subthreshold slope, and charge-pumping methods for several MOS processes and technologies

  2. Flexible Proton-Gated Oxide Synaptic Transistors on Si Membrane.

    Science.gov (United States)

    Zhu, Li Qiang; Wan, Chang Jin; Gao, Ping Qi; Liu, Yang Hui; Xiao, Hui; Ye, Ji Chun; Wan, Qing

    2016-08-24

    Ion-conducting materials have received considerable attention for their applications in fuel cells, electrochemical devices, and sensors. Here, flexible indium zinc oxide (InZnO) synaptic transistors with multiple presynaptic inputs gated by proton-conducting phosphorosilicate glass-based electrolyte films are fabricated on ultrathin Si membranes. Transient characteristics of the proton gated InZnO synaptic transistors are investigated, indicating stable proton-gating behaviors. Short-term synaptic plasticities are mimicked on the proposed proton-gated synaptic transistors. Furthermore, synaptic integration regulations are mimicked on the proposed synaptic transistor networks. Spiking logic modulations are realized based on the transition between superlinear and sublinear synaptic integration. The multigates coupled flexible proton-gated oxide synaptic transistors may be interesting for neuroinspired platforms with sophisticated spatiotemporal information processing.

  3. Graphene-based flexible and stretchable thin film transistors.

    Science.gov (United States)

    Yan, Chao; Cho, Jeong Ho; Ahn, Jong-Hyun

    2012-08-21

    Graphene has been attracting wide attention owing to its superb electronic, thermal and mechanical properties. These properties allow great applications in the next generation of optoelectronics, where flexibility and stretchability are essential. In this context, the recent development of graphene growth/transfer and its applications in field-effect transistors are involved. In particular, we provide a detailed review on the state-of-the-art of graphene-based flexible and stretchable thin film transistors. We address the principles of fabricating high-speed graphene analog transistors and the key issues of producing an array of graphene-based transistors on flexible and stretchable substrates. It provides a platform for future work to focus on understanding and realizing high-performance graphene-based transistors.

  4. Diakoptical reliability analysis of transistorized systems

    International Nuclear Information System (INIS)

    Kontoleon, J.M.; Lynn, J.W.; Green, A.E.

    1975-01-01

    Limitations both on high-speed core availability and computation time required for assessing the reliability of large-sized and complex electronic systems, such as used for the protection of nuclear reactors, are very serious restrictions which continuously confront the reliability analyst. Diakoptic methods simplify the solution of the electrical-network problem by subdividing a given network into a number of independent subnetworks and then interconnecting the solutions of these smaller parts by a systematic process involving transformations based on connection-matrix elements associated with the interconnecting links. However, the interconnection process is very complicated and it may be used only if the original system has been cut in such a manner that a relation can be established between the constraints appearing at both sides of the cut. Also, in dealing with transistorized systems, one of the difficulties encountered is that of modelling adequately their performance under various operating conditions, since their parameters are strongly affected by the imposed voltage and current levels. In this paper a new interconnection approach is presented which may be of use in the reliability analysis of large-sized transistorized systems. This is based on the partial optimization of the subdivisions of the torn network as well as on the optimization of the torn paths. The solution of the subdivisions is based on the principles of algebraic topology, with an algebraic structure relating the physical variables in a topological structure which defines the interconnection of the discrete elements. Transistors, and other nonlinear devices, are modelled using their actual characteristics, under normal and abnormal operating conditions. Use of so-called k factors is made to facilitate accounting for use of electrical stresses. The approach is demonstrated by way of an example. (author)

  5. Collisional charging of individual submillimeter particles: Using ultrasonic levitation to initiate and track charge transfer

    Science.gov (United States)

    Lee, Victor; James, Nicole M.; Waitukaitis, Scott R.; Jaeger, Heinrich M.

    2018-03-01

    Electrostatic charging of insulating fine particles can be responsible for numerous phenomena ranging from lightning in volcanic plumes to dust explosions. However, even basic aspects of how fine particles become charged are still unclear. Studying particle charging is challenging because it usually involves the complexities associated with many-particle collisions. To address these issues, we introduce a method based on acoustic levitation, which makes it possible to initiate sequences of repeated collisions of a single submillimeter particle with a flat plate, and to precisely measure the particle charge in situ after each collision. We show that collisional charge transfer between insulators is dependent on the hydrophobicity of the contacting surfaces. We use glass, which we modify by attaching nonpolar molecules to the particle, the plate, or both. We find that hydrophilic surfaces develop significant positive charges after contacting hydrophobic surfaces. Moreover, we demonstrate that charging between a hydrophilic and a hydrophobic surface is suppressed in an acidic environment and enhanced in a basic one. Application of an electric field during each collision is found to modify the charge transfer, again depending on surface hydrophobicity. We discuss these results within the context of contact charging due to ion transfer, and we show that they lend strong support to O H- ions as the charge carriers.

  6. Submillimeter Array {sup 12}CO (2-1) Imaging of the NGC 6946 Giant Molecular Clouds

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Ya-Lin [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Sakamoto, Kazushi; Pan, Hsi-An, E-mail: yalinwu@email.arizona.edu [Academia Sinica, Institute of Astronomy and Astrophysics, Taiwan (China)

    2017-04-10

    We present a {sup 12}CO (2–1) mosaic map of the spiral galaxy NGC 6946 by combining data from the Submillimeter Array and the IRAM 30 m telescope. We identify 390 giant molecular clouds (GMCs) from the nucleus to 4.5 kpc in the disk. GMCs in the inner 1 kpc are generally more luminous and turbulent, some of which have luminosities >10{sup 6} K km s{sup −1} pc{sup 2} and velocity dispersions >10 km s{sup −1}. Large-scale bar-driven dynamics likely regulate GMC properties in the nuclear region. Similar to the Milky Way and other disk galaxies, GMC mass function of NGC 6946 has a shallower slope (index > −2) in the inner region, and a steeper slope (index < −2) in the outer region. This difference in mass spectra may be indicative of different cloud formation pathways: gravitational instabilities might play a major role in the nuclear region, while cloud coalescence might be dominant in the outer disk. Finally, the NGC 6946 clouds are similar to those in M33 in terms of statistical properties, but they are generally less luminous and turbulent than the M51 clouds.

  7. A New Era of Submillimeter GRB Afterglow Follow-Ups with the Greenland Telescope

    Directory of Open Access Journals (Sweden)

    Yuji Urata

    2015-01-01

    Full Text Available Planned rapid submillimeter (submm gamma-ray-bursts (GRBs follow-up observations conducted using the Greenland Telescope (GLT are presented. The GLT is a 12-m submm telescope to be located at the top of the Greenland ice sheet, where the high altitude and dry weather porvide excellent conditions for observations at submm wavelengths. With its combination of wavelength window and rapid responding system, the GLT will explore new insights on GRBs. Summarizing the current achievements of submm GRB follow-ups, we identify the following three scientific goals regarding GRBs: (1 systematic detection of bright submm emissions originating from reverse shock (RS in the early afterglow phase, (2 characterization of forward shock and RS emissions by capturing their peak flux and frequencies and performing continuous monitoring, and (3 detections of GRBs at a high redshift as a result of the explosion of first generation stars through systematic rapid follow-ups. The light curves and spectra calculated by available theoretical models clearly show that the GLT could play a crucial role in these studies.

  8. A New Era of Submillimeter GRB Afterglow Follow-Ups with the Greenland Telescope

    Science.gov (United States)

    Urata, Yuji; Huang, Kuiyun; Asada, Keiichi; Hirashita, Hiroyuki; Inoue, Makoto; Ho, Paul T. P.

    A planned rapid submillimeter (submm) Gamma Ray Burst (GRBs) follow-up observations conducted using the Greenland Telescope (GLT) is presented. The GLT is a 12-m submm telescope to be located at the top of the Greenland ice sheet, where the high-altitude and dry weather porvides excellent conditions for observations at submm wavelengths. With its combination of wavelength window and rapid responding system, the GLT will explore new insights on GRBs. Summarizing the current achievements of submm GRB follow-ups, we identify the following three scientific goals regarding GRBs: (1) systematic detection of bright submm emissions originating from reverse shock (RS) in the early afterglow phase, (2) characterization of forward shock and RS emissions by capturing their peak flux and frequencies and performing continuous monitoring, and (3) detections of GRBs as a result of the explosion of first-generation stars result of GRBs at a high redshift through systematic rapid follow ups. The light curves and spectra calculated by available theoretical models clearly show that the GLT could play a crucial role in these studies.

  9. Noise performance of the multiwavelength sub/millimeter inductance camera (MUSIC) detectors

    International Nuclear Information System (INIS)

    Siegel, S. R.

    2015-01-01

    MUSIC is a multi-band imaging camera that employs 2304 Microwave Kinetic Inductance Detectors (MKIDs) in 576 spatial pixels to cover a 14 arc-minute field of view, with each pixel simultaneously sensitive to 4 bands centered at 0.87, 1.04, 1.33, and 1.98 mm. In April 2012 the MUSIC instrument was commissioned at the Caltech Submillimeter Observatory with a subset of the full focal plane. We examine the noise present in the detector timestreams during observations taken in the first year of operation. We find that fluctuations in atmospheric emission dominate at long timescales (< 0.5 Hz), and fluctuations in the amplitude and phase of the probe signal due to readout electronics contribute significant 1/f-type noise at shorter timescales. We describe a method to remove the amplitude, phase, and atmospheric noise using the fact that they are correlated among carrier tones. After removal, the complex signal is decomposed, or projected, into dissipation and frequency components. White noise from the cryogenic HEMT amplifier dominates in the dissipation component. An excess noise is observed in the frequency component that is likely due to fluctuations in two-level system (TLS) defects in the device substrate. We compare the amplitude of the TLS noise with previous measurements

  10. Bolometric kinetic inductance detector technology for sub-millimeter radiometric imaging

    Science.gov (United States)

    Hassel, Juha; Timofeev, Andrey V.; Vesterinen, Visa; Sipola, Hannu; Helistö, Panu; Aikio, Mika; Mäyrä, Aki; Grönberg, Leif; Luukanen, Arttu

    2015-10-01

    Radiometric sub-millimeter imaging is a candidate technology especially in security screening applications utilizing the property of radiation in the band of 0.2 - 1.0 THz to penetrate through dielectric substances such as clothing. The challenge of the passive technology is the fact that the irradiance corresponding to the blackbody radiation is very weak in this spectral band: about two orders of magnitude below that of the infrared band. Therefore the role of the detector technology is of ultimate importance to achieve sufficient sensitivity. In this paper we present results related to our technology relying on superconducting kinetic inductance detectors operating in a thermal (bolometric) mode. The detector technology is motivated by the fact that it is naturally suitable for scalable multiplexed readout systems, and operates with relatively simple cryogenics. We will review the basic concepts of the detectors, and provide experimental figures of merit. Furthermore, we will discuss the issues related to the scale-up of our detector technology into large 2D focal plane arrays.

  11. Data Release of UV to Submillimeter Broadband Fluxes for Simulated Galaxies from the EAGLE Project

    Science.gov (United States)

    Camps, Peter; Trčka, Ana; Trayford, James; Baes, Maarten; Theuns, Tom; Crain, Robert A.; McAlpine, Stuart; Schaller, Matthieu; Schaye, Joop

    2018-02-01

    We present dust-attenuated and dust emission fluxes for sufficiently resolved galaxies in the EAGLE suite of cosmological hydrodynamical simulations, calculated with the SKIRT radiative transfer code. The post-processing procedure includes specific components for star formation regions, stellar sources, and diffuse dust and takes into account stochastic heating of dust grains to obtain realistic broadband fluxes in the wavelength range from ultraviolet to submillimeter. The mock survey includes nearly half a million simulated galaxies with stellar masses above {10}8.5 {M}ȯ across six EAGLE models. About two-thirds of these galaxies, residing in 23 redshift bins up to z = 6, have a sufficiently resolved metallic gas distribution to derive meaningful dust attenuation and emission, with the important caveat that the same dust properties were used at all redshifts. These newly released data complement the already publicly available information about the EAGLE galaxies, which includes intrinsic properties derived by aggregating the properties of the smoothed particles representing matter in the simulation. We further provide an open-source framework of Python procedures for post-processing simulated galaxies with the radiative transfer code SKIRT. The framework allows any third party to calculate synthetic images, spectral energy distributions, and broadband fluxes for EAGLE galaxies, taking into account the effects of dust attenuation and emission.

  12. Noise performance of the multiwavelength sub/millimeter inductance camera (MUSIC) detectors

    Science.gov (United States)

    Siegel, S. R.

    2015-07-01

    MUSIC is a multi-band imaging camera that employs 2304 Microwave Kinetic Inductance Detectors (MKIDs) in 576 spatial pixels to cover a 14 arc-minute field of view, with each pixel simultaneously sensitive to 4 bands centered at 0.87, 1.04, 1.33, and 1.98 mm. In April 2012 the MUSIC instrument was commissioned at the Caltech Submillimeter Observatory with a subset of the full focal plane. We examine the noise present in the detector timestreams during observations taken in the first year of operation. We find that fluctuations in atmospheric emission dominate at long timescales (electronics contribute significant 1/f-type noise at shorter timescales. We describe a method to remove the amplitude, phase, and atmospheric noise using the fact that they are correlated among carrier tones. After removal, the complex signal is decomposed, or projected, into dissipation and frequency components. White noise from the cryogenic HEMT amplifier dominates in the dissipation component. An excess noise is observed in the frequency component that is likely due to fluctuations in two-level system (TLS) defects in the device substrate. We compare the amplitude of the TLS noise with previous measurements.

  13. First Observation of the Submillimeter Polarization Spectrum in a Translucent Molecular Cloud

    Science.gov (United States)

    Ashton, Peter C.; Ade, Peter A. R.; Angilè, Francesco E.; Benton, Steven J.; Devlin, Mark J.; Dober, Bradley; Fissel, Laura M.; Fukui, Yasuo; Galitzki, Nicholas; Gandilo, Natalie N.; Klein, Jeffrey; Korotkov, Andrei L.; Li, Zhi-Yun; Martin, Peter G.; Matthews, Tristan G.; Moncelsi, Lorenzo; Nakamura, Fumitaka; Netterfield, Calvin B.; Novak, Giles; Pascale, Enzo; Poidevin, Frédérick; Santos, Fabio P.; Savini, Giorgio; Scott, Douglas; Shariff, Jamil A.; Soler, Juan D.; Thomas, Nicholas E.; Tucker, Carole E.; Tucker, Gregory S.; Ward-Thompson, Derek

    2018-04-01

    Polarized emission from aligned dust is a crucial tool for studies of magnetism in the ISM, but a troublesome contaminant for studies of cosmic microwave background polarization. In each case, an understanding of the significance of the polarization signal requires well-calibrated physical models of dust grains. Despite decades of progress in theory and observation, polarized dust models remain largely underconstrained. During its 2012 flight, the balloon-borne telescope BLASTPol obtained simultaneous broadband polarimetric maps of a translucent molecular cloud at 250, 350, and 500 μm. Combining these data with polarimetry from the Planck 850 μm band, we have produced a submillimeter polarization spectrum, the first for a cloud of this type. We find the polarization degree to be largely constant across the four bands. This result introduces a new observable with the potential to place strong empirical constraints on ISM dust polarization models in a previously inaccessible density regime. Compared to models by Draine & Fraisse, our result disfavors two of their models for which all polarization arises due only to aligned silicate grains. By creating simple models for polarized emission in a translucent cloud, we verify that extinction within the cloud should have only a small effect on the polarization spectrum shape, compared to the diffuse ISM. Thus, we expect the measured polarization spectrum to be a valid check on diffuse ISM dust models. The general flatness of the observed polarization spectrum suggests a challenge to models where temperature and alignment degree are strongly correlated across major dust components.

  14. Control of surface quality of sub-millimeter cylindrical gold targets

    International Nuclear Information System (INIS)

    Zhang Yunwang; Du Kai; Wan Xiaobo; Xiao Jiang; Zheng Wei; Zhang Lin; Sun Jingyuan; Chen Jing

    2010-01-01

    The morphology, composition and causes of defects are analyzed to reduce defects on the gold layer prepared by electrochemical deposition from sulfite solution, and to improve the surface quality of sub-millimeter cylindrical gold targets, by means of SEM and EDS. The effects of current density, metallic impurity, organic pollution, pre-deposition parameters and mandrel quality on the quality of the gold plating are discussed, along with their mechanisms. The result indicates that the current density must be controlled strictly. The optimal current density ranges from 2.4 to 3.2 mA/cm 2 when the concentration of gold ranges from 13 to 22 g/L, and from 2.0 to 2.6 mA/ cm 2 when the concentration of gold ranges from 5 to 13 g/L. The parameters of predeposition must be optimized and the predeposition time should be no longer than 1 minute to improve the surface quality. In addition, organic pollution should be removed from the bath, and the mandrels should be of good quality without oxide on their surfaces. (authors)

  15. Micro-Spec: An Ultracompact, High-sensitivity Spectrometer for Far-Infrared and Submillimeter Astronomy

    Science.gov (United States)

    Cataldo, Giuseppe; Hsieh, Wen-Ting; Huang, Wei-Chung; Moseley, S. Harvey; Stevenson, Thomas R.; Wollack, Edward J.

    2014-01-01

    High-performance, integrated spectrometers operating in the far-infrared and submillimeter ranges promise to be powerful tools for the exploration of the epochs of reionization and initial galaxy formation. These devices, using high-efficiency superconducting transmission lines, can achieve the performance of a meter-scale grating spectrometer in an instrument implemented on a 4 inch silicon wafer. Such a device, when combined with a cryogenic telescope in space, provides an enabling capability for studies of the early universe. Here, the optical design process for Micro-Spec (micron-Spec) is presented, with particular attention given to its two-dimensional diffractive region, where the light of different wavelengths is focused on the different detectors. The method is based on the stigmatization and minimization of the light path function in this bounded region, which results in an optimized geometrical configuration. A point design with an efficiency of (is) approximately 90% has been developed for initial demonstration and can serve as the basis for future instruments. Design variations on this implementation are also discussed, which can lead to lower efficiencies due to diffractive losses in the multimode region.

  16. DETECTION OF AN ULTRA-BRIGHT SUBMILLIMETER GALAXY BEHIND THE SMALL MAGELLANIC CLOUD

    Energy Technology Data Exchange (ETDEWEB)

    Takekoshi, Tatsuya; Minamidani, Tetsuhiro; Sorai, Kazuo; Habe, Asao [Department of Cosmosciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Tamura, Yoichi; Kohno, Kotaro [Institute of Astronomy, University of Tokyo, Osawa, Mitaka, Tokyo 181-0015 (Japan); Oogi, Taira [Department of Physics, Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan); Ezawa, Hajime; Komugi, Shinya; Mizuno, Norikazu; Muller, Erik; Kawamura, Akiko [Chile Observatory, National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan); Oshima, Tai [Nobeyama Radio Observatory, National Astronomical Observatory of Japan, Minamimaki, Minamisaku, Nagano 384-1305 (Japan); Scott, Kimberly S. [North American ALMA Science Center, National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States); Austermann, Jason E. [Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309 (United States); Tosaki, Tomoka [Joetsu University of Education, Joetsu, Niigata 943-8512 (Japan); Onishi, Toshikazu [Department of Physical Science, Osaka Prefecture University, Gakuen 1-1, Sakai, 599-8531 Osaka (Japan); Fukui, Yasuo [Department of Astrophysics, Nagoya University, Chikusa-ku, Nagoya 464-8602 (Japan); Matsuo, Hiroshi [Advanced Technology Center, National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Aretxaga, Itziar [Instituto Nacional de Astrofisica, Optica y Electronica (INAOE), 72000 Puebla (Mexico); and others

    2013-09-10

    We report the discovery of a new ultra-bright submillimeter galaxy (SMG) behind the Small Magellanic Cloud (SMC). This SMG is detected as a 43.3 {+-} 8.4 mJy point source (MM J01071-7302, hereafter MMJ0107) in the 1.1 mm continuum survey of the SMC by AzTEC on the ASTE telescope. MMJ0107 is also detected in the radio (843 MHz), Herschel/SPIRE, Spitzer MIPS 24 {mu}m, all IRAC bands, Wide-field Infrared Survey Explorer, and near-infrared (J, H, K{sub S} ). We find an optical (U, B, V) source, which might be the lensing object, at a distance of 1.''4 from near-infrared and IRAC sources. Photometric redshift estimates for the SMG using representative spectral energy distribution templates show the redshifts of 1.4-3.9. We estimate total far-infrared luminosity of (0.3-2.2) Multiplication-Sign 10{sup 14} {mu}{sup -1} L{sub Sun} and a star formation rate of 5600-39, 000 {mu}{sup -1} M{sub Sun} yr{sup -1}, where {mu} is the gravitational magnification factor. This apparent extreme star formation activity is likely explained by a highly magnified gravitational lens system.

  17. High resolution phoswich gamma-ray imager utilizing monolithic MPPC arrays with submillimeter pixelized crystals

    Science.gov (United States)

    Kato, T.; Kataoka, J.; Nakamori, T.; Kishimoto, A.; Yamamoto, S.; Sato, K.; Ishikawa, Y.; Yamamura, K.; Kawabata, N.; Ikeda, H.; Kamada, K.

    2013-05-01

    We report the development of a high spatial resolution tweezers-type coincidence gamma-ray camera for medical imaging. This application consists of large-area monolithic Multi-Pixel Photon Counters (MPPCs) and submillimeter pixelized scintillator matrices. The MPPC array has 4 × 4 channels with a three-side buttable, very compact package. For typical operational gain of 7.5 × 105 at + 20 °C, gain fluctuation over the entire MPPC device is only ± 5.6%, and dark count rates (as measured at the 1 p.e. level) amount to acrylic light guide measuring 1 mm thick, and with summing operational amplifiers that compile the signals into four position-encoded analog outputs being used for signal readout. Spatial resolution of 1.1 mm was achieved with the coincidence imaging system using a 22Na point source. These results suggest that the gamma-ray imagers offer excellent potential for applications in high spatial medical imaging.

  18. Optical fiber sensors-based temperature distribution measurement in ex vivo radiofrequency ablation with submillimeter resolution.

    Science.gov (United States)

    Macchi, Edoardo Gino; Tosi, Daniele; Braschi, Giovanni; Gallati, Mario; Cigada, Alfredo; Busca, Giorgio; Lewis, Elfed

    2014-01-01

    Radiofrequency thermal ablation (RFTA) induces a high-temperature field in a biological tissue having steep spatial (up to 6°C∕mm) and temporal (up to 1°C∕s) gradients. Applied in cancer care, RFTA produces a localized heating, cytotoxic for tumor cells, and is able to treat tumors with sizes up to 3 to 5 cm in diameter. The online measurement of temperature distribution at the RFTA point of care has been previously carried out with miniature thermocouples and optical fiber sensors, which exhibit problems of size, alteration of RFTA pattern, hysteresis, and sensor density worse than 1 sensor∕cm. In this work, we apply a distributed temperature sensor (DTS) with a submillimeter spatial resolution for the monitoring of RFTA in porcine liver tissue. The DTS demodulates the chaotic Rayleigh backscattering pattern with an interferometric setup to obtain the real-time temperature distribution. A measurement chamber has been set up with the fiber crossing the tissue along different diameters. Several experiments have been carried out measuring the space-time evolution of temperature during RFTA. The present work showcases the temperature monitoring in RFTA with an unprecedented spatial resolution and is exportable to in vivo measurement; the acquired data can be particularly useful for the validation of RFTA computational models.

  19. Progress on Background-Limited Membrane-Isolated TES Bolometers for Far-IR/Submillimeter Spectroscopy

    Science.gov (United States)

    Kenyon, M.; Day, P. K.; Bradford, C. M.; Bock, J. J.; Leduc, H. G.

    2006-01-01

    To determine the lowest attainable phonon noise equivalent power (NEP) for membrane-isolation bolometers, we fabricated and measured the thermal conductance of suspended Si3N4 beams with different geometries via a noise thermometry technique. We measured beam cross-sectional areas ranging from 0.35 x 0.5 (micro)m(sup 2) to 135 x 1.0 (micro)m(sup 2) and beam lengths ranging from (micro)m to 8300 (micro)m. The measurements directly imply that membrane-isolation bolometers are capable of reaching a phonon noise equivalent power (NEP) of 4 x 10(sup -20)W/Hz(sup 1)/O . This NEP adequate for the Background-Limited Infrared-Submillimeter Spectrograph (BLISS) proposed for the Japanese SPICA observatory, and adequate for NASA's SAFIR observatory, a 10-meter, 4 K telescope to be deployed at L2. Further, we measured the heat capacity of a suspended Si3N4 membrane and show how this result implies that one can make membrane-isolation bolometers with a response time which is fast enough for BLISS.

  20. The SOFIA/SAFIRE Far-Infrared Spectrometer: Highlighting Submillimeter Astrophysics and Technology

    Science.gov (United States)

    Benford, Dominic J.

    2009-01-01

    The Submillimeter and Far-InfraRed Experiment (SAFIRE) on the SOFIA airborne observatory is an imaging spectrometer for wavelengths between 28 microns and 440 microns. Our design is a dual-band long-slit grating spectrometer, which provides broadband (approx. 4000 km/s) observations in two lines simultaneously over a field of view roughly 10" wide by 320" long. The low backgrounds in spectroscopy require very sensitive detectors with noise equivalent powers of order 10(exp -18) W/square root of Hz. We are developing a kilopixel, filled detector array for SAFIRE in a 32 x 40 format. The detector consists of a transition edge sensor (TES) bolometer array, a per-pixel broadband absorbing backshort array, and a NIST SQUID multiplexer readout array. This general type of array has been used successfully in the GISMO instrument, so we extrapolate to the sensitivity needed for airborne spectroscopy. Much of the cryogenic, electronics, and software infrastructure for SAFIRE have been developed. I provide here an overview of the progress on SAFIRE.

  1. Development of a Submillimeter Multipass Spectrometer for the Study of Molecular Ions

    Science.gov (United States)

    Carroll, A.; Rocher, B.; Laas, J. C.; Deprince, B. A.; Hays, B.; Weaver, S. L. Widicus; Lang, S.

    2012-06-01

    We have developed a multipass spectrometer for the submillimeter spectral region that is being used to study molecular ions through gas phase spectroscopy. The optical configuration is based on the design of Perry and coworkers that was implemented in the optical regime. To our knowledge, this is the first implementation of this optical configuration at long wavelengths. The setup involves two nearly concentric spherical mirrors that focus the multiple beam passes into a small area, or ``waist'', in the middle of the sample chamber. A supersonic molecular beam is coupled to the setup so that the molecular beam crosses the optical path at the waist. Initial studies have focused on neutral test molecules to probe the physical properties of the molecular beam under various arrangements of the molecular source relative to the optical path. Current studies focus on coupling a plasma discharge source to the setup to enable the study of molecular ions. Here we present the design of this instrument, compare the spectrometer capabilities to a traditional single pass spectrometer, and discuss the results of initial spectroscopic studies.

  2. Measurements of dose with individual FAMOS transistors

    Energy Technology Data Exchange (ETDEWEB)

    Scheick, L.Z.; McNulty, P.J.; Roth, D.R.; Davis, M.G.; Mason, B.E.

    1999-12-01

    A new method is described for measuring the doses absorbed by microstructures from an exposure to ionizing radiation. The decrease in the duration of UltraViolet light (UV) exposure required to erase each cell of a commercial UltraViolet erasable Programmable Read Only Memory (UVPROM) correlates with the dose absorbed by the floating gate of that transistor. This technique facilitates analysis of the microdose distribution across the array and the occurrence of Single Event Upset (SEU) like anomalous shifts due to rare large energy-deposition events.

  3. Measurements of dose with individual FAMOS transistors

    International Nuclear Information System (INIS)

    Scheick, L.Z.; McNulty, P.J.; Roth, D.R.; Davis, M.G.; Mason, B.E.

    1999-01-01

    A new method is described for measuring the doses absorbed by microstructures from an exposure to ionizing radiation. The decrease in the duration of UltraViolet light (UV) exposure required to erase each cell of a commercial UltraViolet erasable Programmable Read Only Memory (UVPROM) correlates with the dose absorbed by the floating gate of that transistor. This technique facilitates analysis of the microdose distribution across the array and the occurrence of Single Event Upset (SEU) like anomalous shifts due to rare large energy-deposition events

  4. Pass-transistor asynchronous sequential circuits

    Science.gov (United States)

    Whitaker, Sterling R.; Maki, Gary K.

    1989-01-01

    Design methods for asynchronous sequential pass-transistor circuits, which result in circuits that are hazard- and critical-race-free and which have added degrees of freedom for the input signals, are discussed. The design procedures are straightforward and easy to implement. Two single-transition-time state assignment methods are presented, and hardware bounds for each are established. A surprising result is that the hardware realizations for each next state variable and output variable is identical for a given flow table. Thus, a state machine with N states and M outputs can be constructed using a single layout replicated N + M times.

  5. Amplificadores con transistores. Estudio y dimensionado

    OpenAIRE

    Lubiano García, Adrián

    2017-01-01

    Este trabajo es un estudio de las distintas configuraciones de los amplificadores con transistores vistos en la asignatura de Electrónica Analógica del tercer curso del Grado en Ingeniería en Electrónica Industrial y Automática de la Escuela de Ingenierías Industriales de la Universidad de Valladolid. En este trabajo se mostrarán los pasos seguidos en la creación de una aplicación con Visual Basic para la realización de los ejercicios de las distintas configuraciones, así...

  6. Microwave Enhanced Cotunneling in SET Transistors

    DEFF Research Database (Denmark)

    Manscher, Martin; Savolainen, M.; Mygind, Jesper

    2003-01-01

    Cotunneling in single electron tunneling (SET) devices is an error process which may severely limit their electronic and metrologic applications. Here is presented an experimental investigation of the theory for adiabatic enhancement of cotunneling by coherent microwaves. Cotunneling in SET...... transistors has been measured as function of temperature, gate voltage, frequency, and applied microwave power. At low temperatures and applied power levels, including also sequential tunneling, the results can be made consistent with theory using the unknown damping in the microwave line as the only free...

  7. Advancement in organic nanofiber based transistors

    DEFF Research Database (Denmark)

    Jensen, Per Baunegaard With; Kjelstrup-Hansen, Jakob; Tavares, Luciana

    and characterization of OLETs using the organic semiconductors para-hexaphenylene (p6P), 5,5´-Di-4-biphenyl-2,2´-bithiophene (PPTTPP) and 5,5'-bis(naphth-2-yl)-2,2'-bithiophene (NaT2). These molecules can self-assemble forming molecular crystalline nanofibers. Organic nanofibers can form the basis for light......The focus of this project is to study the light emission from nanofiber based organic light-emitting transistors (OLETs) with the overall aim of developing efficient, nanoscale light sources with different colors integrated on-chip. The research performed here regards the fabrication...

  8. Carbon Based Transistors and Nanoelectronic Devices

    Science.gov (United States)

    Rouhi, Nima

    Carbon based materials (carbon nanotube and graphene) has been extensively researched during the past decade as one of the promising materials to be used in high performance device technology. In long term it is thought that they may replace digital and/or analog electronic devices, due to their size, near-ballistic transport, and high stability. However, a more realistic point of insertion into market may be the printed nanoelectronic circuits and sensors. These applications include printed circuits for flexible electronics and displays, large-scale bendable electrical contacts, bio-membranes and bio sensors, RFID tags, etc. In order to obtain high performance thin film transistors (as the basic building block of electronic circuits) one should be able to manufacture dense arrays of all semiconducting nanotubes. Besides, graphene synthesize and transfer technology is in its infancy and there is plenty of room to improve the current techniques. To realize the performance of nanotube and graphene films in such systems, we need to economically fabricate large-scale devices based on these materials. Following that the performance control over such devices should also be considered for future design variations for broad range of applications. Here we have first investigated carbon nanotube ink as the base material for our devices. The primary ink used consisted of both metallic and semiconducting nanotubes which resulted in networks suitable for moderate-resistivity electrical connections (such as interconnects) and rfmatching circuits. Next, purified all-semiconducting nanotube ink was used to fabricate waferscale, high performance (high mobility, and high on/off ratio) thin film transistors for printed electronic applications. The parameters affecting device performance were studied in detail to establish a roadmap for the future of purified nanotube ink printed thin film transistors. The trade of between mobility and on/off ratio of such devices was studied and the

  9. Dose Rate Effects in Linear Bipolar Transistors

    Science.gov (United States)

    Johnston, Allan; Swimm, Randall; Harris, R. D.; Thorbourn, Dennis

    2011-01-01

    Dose rate effects are examined in linear bipolar transistors at high and low dose rates. At high dose rates, approximately 50% of the damage anneals at room temperature, even though these devices exhibit enhanced damage at low dose rate. The unexpected recovery of a significant fraction of the damage after tests at high dose rate requires changes in existing test standards. Tests at low temperature with a one-second radiation pulse width show that damage continues to increase for more than 3000 seconds afterward, consistent with predictions of the CTRW model for oxides with a thickness of 700 nm.

  10. Modelling transport in single electron transistor

    International Nuclear Information System (INIS)

    Dinh Sy Hien; Huynh Lam Thu Thao; Le Hoang Minh

    2009-01-01

    We introduce a model of single electron transistor (SET). Simulation programme of SET is used as the exploratory tool in order to gain better understanding of process and device physics. This simulator includes a graphic user interface (GUI) in Matlab. The SET was simulated using GUI in Matlab to get current-voltage (I-V) characteristics. In addition, effects of device capacitance, bias, temperature on the I-V characteristics were obtained. In this work, we review the capabilities of the simulator of the SET. Typical simulations of the obtained I-V characteristics of the SET are presented.

  11. Plasma waves

    CERN Document Server

    Swanson, DG

    1989-01-01

    Plasma Waves discusses the basic development and equations for the many aspects of plasma waves. The book is organized into two major parts, examining both linear and nonlinear plasma waves in the eight chapters it encompasses. After briefly discussing the properties and applications of plasma wave, the book goes on examining the wave types in a cold, magnetized plasma and the general forms of the dispersion relation that characterize the waves and label the various types of solutions. Chapters 3 and 4 analyze the acoustic phenomena through the fluid model of plasma and the kinetic effects. Th

  12. Stable organic thin-film transistors

    Science.gov (United States)

    Jia, Xiaojia; Fuentes-Hernandez, Canek; Wang, Cheng-Yin; Park, Youngrak; Kippelen, Bernard

    2018-01-01

    Organic thin-film transistors (OTFTs) can be fabricated at moderate temperatures and through cost-effective solution-based processes on a wide range of low-cost flexible and deformable substrates. Although the charge mobility of state-of-the-art OTFTs is superior to that of amorphous silicon and approaches that of amorphous oxide thin-film transistors (TFTs), their operational stability generally remains inferior and a point of concern for their commercial deployment. We report on an exhaustive characterization of OTFTs with an ultrathin bilayer gate dielectric comprising the amorphous fluoropolymer CYTOP and an Al2O3:HfO2 nanolaminate. Threshold voltage shifts measured at room temperature over time periods up to 5.9 × 105 s do not vary monotonically and remain below 0.2 V in microcrystalline OTFTs (μc-OTFTs) with field-effect carrier mobility values up to 1.6 cm2 V−1 s−1. Modeling of these shifts as a function of time with a double stretched-exponential (DSE) function suggests that two compensating aging mechanisms are at play and responsible for this high stability. The measured threshold voltage shifts at temperatures up to 75°C represent at least a one-order-of-magnitude improvement in the operational stability over previous reports, bringing OTFT technologies to a performance level comparable to that reported in the scientific literature for other commercial TFTs technologies. PMID:29340301

  13. Instrument employing a charge flow transistor

    International Nuclear Information System (INIS)

    1981-01-01

    The invention concerns instruments employing charge-flow transistors that operate to sense a property in the surrounding environment. It is based on a particular sensor principle, thin-film conduction. The instruments described include a charge-flow transistor with semiconductor substrate, a source region, a drain region, a gate insulator, and a gapped electrode structure with a thin-film sensor material in the gap. The sensor material has an electrical conductance that is sensitive to a property of the ambient environment and has a surface conductance that differs substantially from its bulk conductance. The main object is to provide a low-cost instrument for early-warning fire-detection devices: in this case the property detected would be the products of combustion. Other properties that can be sensed include gases or vapors, free radicals, vapor electromagnetic radiation, subatomic particles, atomic or molecular beams, changes in ambient pressure or temperature, the chemical composition and the electrochemical potential of a solution. (U.K.)

  14. Optimized thermal amplification in a radiative transistor

    Energy Technology Data Exchange (ETDEWEB)

    Prod' homme, Hugo; Ordonez-Miranda, Jose; Ezzahri, Younes, E-mail: younes.ezzahri@univ-poitiers.fr; Drevillon, Jeremie; Joulain, Karl [Institut Pprime, CNRS, Université de Poitiers, ISAE-ENSMA, F-86962 Futuroscope Chasseneuil (France)

    2016-05-21

    The thermal performance of a far-field radiative transistor made up of a VO{sub 2} base in between a blackbody collector and a blackbody emitter is theoretically studied and optimized. This is done by using the grey approximation on the emissivity of VO{sub 2} and deriving analytical expressions for the involved heat fluxes and transistor amplification factor. It is shown that this amplification factor can be maximized by tuning the base temperature close to its critical one, which is determined by the temperature derivative of the VO{sub 2} emissivity and the equilibrium temperatures of the collector and emitter. This maximization is the result of the presence of two bi-stable temperatures appearing during the heating and cooling processes of the VO{sub 2} base and enables a thermal switching (temperature jump) characterized by a sizeable variation of the collector-to-base and base-to-emitter heat fluxes associated with a slight change of the applied power to the base. This switching effect leads to the optimization of the amplification factor and therefore it could be used for thermal modulation purposes.

  15. Room Temperature Silicene Field-Effect Transistors

    Science.gov (United States)

    Akinwande, Deji

    Silicene, a buckled Si analogue of graphene, holds significant promise for future electronics beyond traditional CMOS. In our predefined experiments via encapsulated delamination with native electrodes approach, silicene devices exhibit an ambipolar charge transport behavior, corroborating theories on Dirac band in Ag-free silicene. Monolayer silicene device has extracted field-effect mobility within the theoretical expectation and ON/OFF ratio greater than monolayer graphene, while multilayer silicene devices show decreased mobility and gate modulation. Air-stability of silicene devices depends on the number of layers of silicene and intrinsic material structure determined by growth temperature. Few or multi-layer silicene devices maintain their ambipolar behavior for days in contrast to minutes time scale for monolayer counterparts under similar conditions. Multilayer silicene grown at different temperatures below 300oC possess different intrinsic structures and yield different electrical property and air-stability. This work suggests a practical prospect to enable more air-stable silicene devices with layer and growth condition control, which can be leveraged for other air-sensitive 2D materials. In addition, we describe quantum and classical transistor device concepts based on silicene and related buckled materials that exploit the 2D topological insulating phenomenon. The transistor device physics offer the potential for ballistic transport that is robust against scattering and can be employed for both charge and spin transport. This work was supported by the ARO.

  16. Instrument employing a charge flow transistor

    Energy Technology Data Exchange (ETDEWEB)

    1981-03-11

    The invention concerns instruments employing charge-flow transistors that operate to sense a property in the surrounding environment. It is based on a particular sensor principle, thin-film conduction. The instruments described include a charge-flow transistor with semiconductor substrate, a source region, a drain region, a gate insulator, and a gapped electrode structure with a thin-film sensor material in the gap. The sensor material has an electrical conductance that is sensitive to a property of the ambient environment and has a surface conductance that differs substantially from its bulk conductance. The main object is to provide a low-cost instrument for early-warning fire-detection devices: in this case the property detected would be the products of combustion. Other properties that can be sensed include gases or vapors, free radicals, vapor electromagnetic radiation, subatomic particles, atomic or molecular beams, changes in ambient pressure or temperature, the chemical composition and the electrochemical potential of a solution.

  17. Heat Waves

    Science.gov (United States)

    Heat Waves Dangers we face during periods of very high temperatures include: Heat cramps: These are muscular pains and spasms due ... that the body is having trouble with the heat. If a heat wave is predicted or happening… - ...

  18. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Brorsen, Michael; Frigaard, Peter

    Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star.......Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star....

  19. Gravitational Waves

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Jonah Maxwell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-10-18

    This report has slides on Gravitational Waves; Pound and Rebka: A Shocking Fact; Light is a Ruler; Gravity is the Curvature of Spacetime; Gravitational Waves Made Simple; How a Gravitational Wave Affects Stuff Here; LIGO; This Detection: Neutron Stars; What the Gravitational Wave Looks Like; The Sound of Merging Neutron Stars; Neutron Star Mergers: More than GWs; The Radioactive Cloud; The Kilonova; and finally Summary, Multimessenger Astronomy.

  20. Enhanced traveling wave amplification of co-planar slow wave structure by extended phase-matching

    International Nuclear Information System (INIS)

    Palm, Andrew; Sirigiri, Jagadishwar; Shin, Young-Min

    2015-01-01

    The electron beam co-propagating with slow waves in a staggered double grating array (SDGA) efficiently amplifies millimeter and sub-millimeter waves over a wide spectrum. Our theoretical and numerical analyses show that the power amplification in the fundamental passband is enhanced by the extended beam-wave phase-matching. Particle-in-cell simulations on the SDGA slow wave structure, designed with 10.4 keV and 50–100 mA sheet beam, indicate that maintaining beam-wave synchronization along the entire length of the circuit improves the gain by 7.3% leading to a total gain of 28 dB, corresponding to 62 W saturated power at the middle of operating band, and a 3-dB bandwidth of 7 GHz with 10.5% at V-band (73.5 GHz center frequency) with saturated peak power reaching 80 W and 28 dB at 71 GHz. These results also show a reasonably good agreement with analytic calculations based on Pierce small signal gain theory

  1. Wave phenomena

    CERN Document Server

    Towne, Dudley H

    1988-01-01

    This excellent undergraduate-level text emphasizes optics and acoustics, covering inductive derivation of the equation for transverse waves on a string, acoustic plane waves, boundary-value problems, polarization, three-dimensional waves and more. With numerous problems (solutions for about half). ""The material is superbly chosen and brilliantly written"" - Physics Today. Problems. Appendices.

  2. Electromagnetic Waves

    DEFF Research Database (Denmark)

    This book is dedicated to various aspects of electromagnetic wave theory and its applications in science and technology. The covered topics include the fundamental physics of electromagnetic waves, theory of electromagnetic wave propagation and scattering, methods of computational analysis......, material characterization, electromagnetic properties of plasma, analysis and applications of periodic structures and waveguide components, etc....

  3. Wave Dragon

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter; Sørensen, H. C.

    1998-01-01

    This paper concerns with the development of the wave energy converter (WEC) Wave Dragon. This WEC is based on the overtopping principle. An overview of the performed research done concerning the Wave Dragon over the past years is given, and the results of one of the more comprehensive studies, co...

  4. High-resolution submillimeter and near-infrared studies of the transition disk around Sz 91

    Energy Technology Data Exchange (ETDEWEB)

    Tsukagoshi, Takashi; Momose, Munetake [College of Science, Ibaraki University, Bunkyo 2-1-1, Mito 310-8512 (Japan); Hashimoto, Jun [Department of Physics and Astronomy, The University of Oklahoma, 440 West Brooks Street, Norman, OK 73019 (United States); Kudo, Tomoyuki; Saito, Masao; Ohashi, Nagayoshi; Kawabe, Ryohei; Akiyama, Eiji [National Astronomical Observatory Japan (NAOJ), Osawa 2-21-1, Mitaka, Tokyo 181-8588 (Japan); Andrews, Sean; Wilner, David [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Kitamura, Yoshimi [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Yoshinodai 3-1-1, Sagamihara, Kanagawa 229-8510 (Japan); Abe, Lyu [Lboratoire Lagrange (UMR 7293), Université de Nice-Sophia Antipolis, CNRS, Observatoire de la Côte d' Azur, 28 avenue Valrose, F-06108 Nice Cedex 2 (France); Brandner, Wolfgang [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Brandt, Timothy D. [Department of Astrophysical Sciences, Princeton University, Peyton Hall, Ivy Lane, Princeton, NJ 08544 (United States); Carson, Joseph [Department of Physics and Astronomy, College of Charleston, 58 Coming Street, Charleston, SC 29424 (United States); Currie, Thayne [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street M5S 3H4, Toronto, Ontario (Canada); Egner, Sebastian E.; Guyon, Olivier [Subaru Telescope, 650 North A' ohoku Place, Hilo, HI 96720 (United States); Goto, Miwa [Universitäts-Sternwarte München, Ludwig-Maximilians-Universität, Scheinerstr. 1, D-81679 München (Germany); Grady, Carol, E-mail: ttsuka@mx.ibaraki.ac.jp [Exoplanets and Stellar Astrophysics Laboratory, Code 667, Goddard Space Flight Center, Greenbelt, MD 20771 (United States); and others

    2014-03-10

    To reveal the structures of a transition disk around a young stellar object in Lupus, Sz 91 , we have performed aperture synthesis 345 GHz continuum and CO(3-2) observations with the Submillimeter Array (∼1''-3'' resolution) and high-resolution imaging of polarized intensity at the K{sub s} -band using the HiCIAO instrument on the Subaru Telescope (0.''25 resolution). Our observations successfully resolved the inner and outer radii of the dust disk to be 65 and 170 AU, respectively, which indicates that Sz 91 is a transition disk source with one of the largest known inner holes. The model fitting analysis of the spectral energy distribution reveals an H{sub 2} mass of 2.4 × 10{sup –3} M {sub ☉} in the cold (T < 30 K) outer part at 65 AU 3 × 10{sup –9} M {sub ☉}) of hot (T ∼ 180 K) dust possibly remains inside the inner hole of the disk. The structure of the hot component could be interpreted as either an unresolved self-luminous companion body (not directly detected in our observations) or a narrow ring inside the inner hole. Significant CO(3-2) emission with a velocity gradient along the major axis of the dust disk is concentrated on the Sz 91 position, suggesting a rotating gas disk with a radius of 420 AU. The Sz 91 disk is possibly a rare disk in an evolutionary stage immediately after the formation of protoplanets because of the large inner hole and the lower disk mass than other transition disks studied thus far.

  5. THE CIRCUMGALACTIC MEDIUM OF SUBMILLIMETER GALAXIES. I. FIRST RESULTS FROM A RADIO-IDENTIFIED SAMPLE

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Hai; Mutel, R.; Isbell, J.; Lang, C.; McGinnis, D. [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States); Hennawi, J. F. [Max-Planck-Institut fur Astronomie, Heidelberg (Germany); Prochaska, J. X. [Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Casey, C. [Department of Astronomy, the University of Texas at Austin, 2515 Speedway Blvd, Stop C1400, Austin, TX 78712 (United States); Cooray, A. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Kereš, D. [Department of Physics, Center for Astrophysics and Space Sciences, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (United States); Zhang, Z.-Y.; Michałowski, M. J. [Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Clements, D. [Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom); Mooley, K. [Oxford Centre For Astrophysical Surveys, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United States); Perley, D. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 København Ø (Denmark); Stockton, A. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Thompson, D. [Large Binocular Telescope Observatory, University of Arizona, 933 N. Cherry Ave, Tucson, AZ 85721 (United States)

    2016-11-20

    We present the first results from an ongoing survey to characterize the circumgalactic medium (CGM) of massive high-redshift galaxies detected as submillimeter galaxies (SMGs). We constructed a parent sample of 163 SMG–QSO pairs with separations less than ∼36″ by cross-matching far-infrared-selected galaxies from Herschel with spectroscopically confirmed QSOs. The Herschel sources were selected to match the properties of the SMGs. We determined the sub-arcsecond positions of six Herschel sources with the Very Large Array and obtained secure redshift identification for three of those with near-infrared spectroscopy. The QSO sightlines probe transverse proper distances of 112, 157, and 198 kpc at foreground redshifts of 2.043, 2.515, and 2.184, respectively, which are comparable to the virial radius of the ∼10{sup 13} M {sub ⊙} halos expected to host SMGs. High-quality absorption-line spectroscopy of the QSOs reveals systematically strong H i Ly α absorption around all three SMGs, with rest-frame equivalent widths of ∼2–3 Å. However, none of the three absorbers exhibit compelling evidence for optically thick H i gas or metal absorption, in contrast to the dominance of strong neutral absorbers in the CGM of luminous z ∼ 2 QSOs. The low covering factor of optically thick H i gas around SMGs tentatively indicates that SMGs may not have as prominent cool gas reservoirs in their halos as the coeval QSOs and that they may inhabit less massive halos than previously thought.

  6. Polarization difference due to nonrandomly oriented ice particles at millimeter/submillimeter waveband

    International Nuclear Information System (INIS)

    Xie Xinxin; Miao Jungang

    2011-01-01

    This paper presents polarized signature due to oriented circular columnar and planar ice crystals at millimeter/submillimeter (mm/sub-mm) waveband. DDSCAT 6.1 and RT4 code package are employed for scattering properties and radiative transfer simulations, respectively, at the three estimated window frequencies (150, 220 and 340 GHz) of FengYun-4 (FY-4). We use empirical formulas to describe realistic sizes of planar and columnar particles and assume that ice particles are in Gamma-size distribution in this study. A 'resonance' feature of polarized signals as a function of median mass diameter is notably found for horizontally oriented columns and blunt plates at the frequency of 340 GHz; however, there is no promising resonance characteristic for horizontally aligned plates with empirical sizes at the three window channels of FY-4. The position of the resonance peak is related to particle aspect ratio, frequency and ice water path (IWP), and it moves to a shorter median mass diameter when the particle aspect ratio decreases or IWP in clouds increases. Considering that particle canting angle distribution (Gaussian distribution in this study), polarization difference, as well as the brightness temperature difference between clear and cloudy sky, decreases rapidly when particles gradually change from horizontally oriented to randomly oriented. The upwelling brightness temperature is insensitive to particle size and shape but sensitive to particle orientation, the difference of brightness temperature between horizontal and random orientation up to 6 K, whereas polarized signature is quite sensitive to particle microphysics as well as orientation; polarized measurements thereby could benefit retrieval of cloud microphysical parameters.

  7. THE CHROMOSPHERIC SOLAR LIMB BRIGHTENING AT RADIO, MILLIMETER, SUB-MILLIMETER, AND INFRARED WAVELENGTHS

    Energy Technology Data Exchange (ETDEWEB)

    De la Luz, V. [Conacyt—SCiESMEX, Instituto de Geofísica, Unidad Michoacán, Universidad Nacional Autónoma de México, Morelia, Michoacán, 58190, México (Mexico)

    2016-07-10

    Observations of the emission at radio, millimeter, sub-millimeter, and infrared wavelengths in the center of the solar disk validate the autoconsistence of semi-empirical models of the chromosphere. Theoretically, these models must reproduce the emission at the solar limb. In this work, we tested both the VALC and C7 semi-empirical models by computing their emission spectrum in the frequency range from 2 GHz to 10 THz at solar limb altitudes. We calculate the Sun's theoretical radii as well as their limb brightening. Non-local thermodynamic equilibrium was computed for hydrogen, electron density, and H{sup −}. In order to solve the radiative transfer equation, a three-dimensional (3D) geometry was employed to determine the ray paths, and Bremsstrahlung, H{sup −}, and inverse Bremsstrahlung opacity sources were integrated in the optical depth. We compared the computed solar radii with high-resolution observations at the limb obtained by Clark. We found that there are differences between the observed and computed solar radii of 12,000 km at 20 GHz, 5000 km at 100 GHz, and 1000 km at 3 THz for both semi-empirical models. A difference of 8000 km in the solar radii was found when comparing our results against the heights obtained from H α observations of spicules-off at the solar limb. We conclude that the solar radii cannot be reproduced by VALC and C7 semi-empirical models at radio—infrared wavelengths. Therefore, the structures in the high chromosphere provide a better measurement of the solar radii and their limb brightening as shown in previous investigations.

  8. Micro-Spec: an Integrated, Direct-Detection Spectrometer for Far-Infrared and Submillimeter Astronomy

    Science.gov (United States)

    Cataldo, Giuseppe

    2014-01-01

    The far-infrared and submillimeter portions of the electromagnetic spectrum provide a unique view of the astrophysical processes present in the early universe. Our ability to fully explore this rich spectral region has been limited, however, by the size and cost of the cryogenic spectrometers required to carry out such measurements. Micro-Spec (u-Spec) is a high-sensitivity, direct-detection spectrometer concept working in the 450-1000 micromillimeter wavelength range which will enable a wide range of flight missions that would otherwise be challenging due to the large size of current instruments with the required spectral resolution and sensitivity. The spectrometer design utilizes two internal antenna arrays, one for transmitting and one for receiving, superconducting microstrip transmission lines for power division and phase delay, and an array of microwave kinetic inductance detectors (MKIDs) to achieve these goals. The instrument will be integrated on a approximately 10 square cm silicon chip and can therefore become an important capability under the low background conditions accessible via space and high-altitude borne platforms. In this paper, an optical design methodology for Micro-Spec is presented, with particular attention given to its twodimensional diffractive region, where the light of different wavelengths is focused on the different detectors. The method is based on the maximization of the instrument resolving power and minimization of the RMS phase error on the instrument focal plane. This two-step optimization can generate geometrical configurations given specific requirements on spectrometer size, operating spectral range and performance. A point design with resolving power of 257, an RMS phase error less than 0.1 radians and four stigmatic points was developed for initial demonstration and will be the basis of future instruments with resolving power up to about 1200.

  9. THE CHROMOSPHERIC SOLAR LIMB BRIGHTENING AT RADIO, MILLIMETER, SUB-MILLIMETER, AND INFRARED WAVELENGTHS

    International Nuclear Information System (INIS)

    De la Luz, V.

    2016-01-01

    Observations of the emission at radio, millimeter, sub-millimeter, and infrared wavelengths in the center of the solar disk validate the autoconsistence of semi-empirical models of the chromosphere. Theoretically, these models must reproduce the emission at the solar limb. In this work, we tested both the VALC and C7 semi-empirical models by computing their emission spectrum in the frequency range from 2 GHz to 10 THz at solar limb altitudes. We calculate the Sun's theoretical radii as well as their limb brightening. Non-local thermodynamic equilibrium was computed for hydrogen, electron density, and H − . In order to solve the radiative transfer equation, a three-dimensional (3D) geometry was employed to determine the ray paths, and Bremsstrahlung, H − , and inverse Bremsstrahlung opacity sources were integrated in the optical depth. We compared the computed solar radii with high-resolution observations at the limb obtained by Clark. We found that there are differences between the observed and computed solar radii of 12,000 km at 20 GHz, 5000 km at 100 GHz, and 1000 km at 3 THz for both semi-empirical models. A difference of 8000 km in the solar radii was found when comparing our results against the heights obtained from H α observations of spicules-off at the solar limb. We conclude that the solar radii cannot be reproduced by VALC and C7 semi-empirical models at radio—infrared wavelengths. Therefore, the structures in the high chromosphere provide a better measurement of the solar radii and their limb brightening as shown in previous investigations.

  10. A submillimeter galaxy illuminating its circumgalactic medium: Lyα scattering in a cold, clumpy outflow

    Energy Technology Data Exchange (ETDEWEB)

    Geach, J. E.; Coppin, K. E. K.; Smith, D. J. B. [Center for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Bower, R. G.; Alexander, D. M.; Swinbank, A. M. [Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Blain, A. W. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Bremer, M. N. [School of Physics, HH Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Chapin, E. L. [XMM SOC, ESAC, Apartado 78, E-28691 Villanueva de la Canada, Madrid (Spain); Chapman, S. C. [Department of Physics and Atmospheric Science, Dalhousie University Halifax, NS B3H 3J5 (Canada); Clements, D. L. [Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom); Dunlop, J. S.; Koprowski, M. P.; Michałowski, M. J. [Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Farrah, D. [Virginia Polytechnic Institute and State University Department of Physics, MC 0435, 910 Drillfield Drive, Blacksburg, VA 24061 (United States); Jenness, T. [Joint Astronomy Centre, 660 North A' ohoku Place University Park, Hilo, HI 96720 (United States); Robson, E. I. [UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Scott, D. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Spaans, M. [Kapteyn Institute, University of Groningen, PO Box 800, 9700 AV Groningen (Netherlands); Van der Werf, P., E-mail: j.geach@herts.ac.uk [Leiden Observatory, Leiden University, PO box 9513, 2300 RA Leiden (Netherlands)

    2014-09-20

    We report the detection at 850 μm of the central source in SSA22-LAB1, the archetypal 'Lyman-α Blob' (LAB), a 100 kpc scale radio-quiet emission-line nebula at z = 3.1. The flux density of the source, S {sub 850} = 4.6 ± 1.1 mJy, implies the presence of a galaxy or group of galaxies with a total luminosity of L {sub IR} ≈ 10{sup 12} L {sub ☉}. The position of an active source at the center of a ∼50 kpc radius ring of linearly polarized Lyα emission detected by Hayes et al. suggests that the central source is leaking Lyα photons preferentially in the plane of the sky, which undergo scattering in H I clouds at a large galactocentric radius. The Lyα morphology around the submillimeter detection is reminiscent of a biconical outflow, and the average Lyα line profiles of the two 'lobes' are dominated by a red peak, which is expected for a resonant line emerging from a medium with a bulk velocity gradient that is outflowing relative to the line center. Taken together, these observations provide compelling evidence that the central active galaxy (or galaxies) is responsible for a large fraction of the extended Lyα emission and morphology. Less clear is the history of the cold gas in the circumgalactic medium being traced by Lyα: is it mainly pristine material accreting into the halo that has not yet been processed through an interstellar medium (ISM), now being blown back as it encounters an outflow, or does it mainly comprise gas that has been swept-up within the ISM and expelled from the galaxy?.

  11. NO CLEAR SUBMILLIMETER SIGNATURE OF SUPPRESSED STAR FORMATION AMONG X-RAY LUMINOUS ACTIVE GALACTIC NUCLEI

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, C. M.; Alexander, D. M.; Mullaney, J. R.; Del Moro, A.; Rovilos, E. [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Altieri, B.; Coia, D. [Herschel Science Centre, European Space Astronomy Centre, Villanueva de la Canada, E-28691 Madrid (Spain); Charmandaris, V. [Department of Physics and Institute of Theoretical and Computation Physics, University of Crete, 71003 Heraklion (Greece); Daddi, E.; Le Floc' h, E.; Leiton, R. [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, Irfu/Service d Astrophysique, CEA-Saclay, Orme des Merisiers, F-91191 Gif-sur-Yvette Cedex (France); Dannerbauer, H. [Insitut fuer Astrophysik, Universitaet Wien, Tuerkenschanzstrasse 17, A-1180 Wien (Austria); Dasyra, K. [Observatoire de Paris, LERMA (CNRS:UMR8112), 61 Av. de l' Observatoire, F-75014 Paris (France); Dickinson, M.; Kartaltepe, J. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Hickox, R. C. [Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, NH 03755 (United States); Ivison, R. J. [UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Magnelli, B.; Popesso, P.; Rosario, D. [Max-Planck-Institut fuer Extraterrestrische Physik (MPE), Postfach 1312, D-85741 Garching (Germany); and others

    2012-11-20

    Many theoretical models require powerful active galactic nuclei (AGNs) to suppress star formation in distant galaxies and reproduce the observed properties of today's massive galaxies. A recent study based on Herschel-SPIRE submillimeter observations claimed to provide direct support for this picture, reporting a significant decrease in the mean star formation rates (SFRs) of the most luminous AGNs (L{sub X} >10{sup 44} erg s{sup -1}) at z Almost-Equal-To 1-3 in the Chandra Deep Field-North (CDF-N). In this Letter, we extend these results using Herschel-SPIRE 250 {mu}m data in the COSMOS and Chandra Deep Field-South fields to achieve an order-of-magnitude improvement in the number of sources at L{sub X} >10{sup 44} erg s{sup -1}. On the basis of our analysis, we find no strong evidence for suppressed star formation in L{sub X} >10{sup 44} erg s{sup -1} AGNs at z Almost-Equal-To 1-3. The mean SFRs of the AGNs are constant over the broad X-ray luminosity range of L{sub X} Almost-Equal-To 10{sup 43}-10{sup 45} erg s{sup -1} (with mean SFRs consistent with typical star-forming galaxies at z Almost-Equal-To 2; (SFRs) Almost-Equal-To 100-200 M{sub Sun} yr{sup -1}). We suggest that the previous CDF-N results were likely due to low number statistics. We discuss our results in the context of current theoretical models.

  12. SUBMILLIMETER ARRAY OBSERVATIONS TOWARD THE MASSIVE STAR-FORMING CORE MM1 OF W75N

    International Nuclear Information System (INIS)

    Minh, Y. C.; Su, Y.-N.; Liu, S.-Y.; Yan, C.-H.; Chen, H.-R.; Kim, S.-J.

    2010-01-01

    The massive star-forming core MM1 of W75N was observed using the Submillimeter Array with ∼1'' and 2'' spatial resolutions at 217 and 347 GHz, respectively. From the 217 GHz continuum we found that the MM1 core consists of two sources, separated by about 1'': MM1a (∼0.6 M sun ) and MM1b (∼1.4 M sun ), located near the radio continuum sources VLA 2/VLA 3 and VLA 1, respectively. Within MM1b, two gas clumps were found to be expanding away from VLA 1 at about ±3 km s -1 , as a result of the most recent star formation activity in the region. Observed molecular lines show emission peaks at two positions, MM1a and MM1b: sulfur-bearing species have emission peaks toward MM1a, but methanol and saturated species at MM1b. We identified high-temperature (∼200 K) gas toward MM1a and the hot core in MM1b. This segregation may result from the evolution of the massive star-forming core. In the very early phase of star formation, the hot core is seen through the evaporation of dust ice-mantle species. As the mantle species are consumed via evaporation the high-temperature gas species (such as the sulfur-bearing molecules) become bright. The SiO molecule is unique in having an emission peak exactly at the VLA 2 position, probably tracing a shock powered by VLA 2. The observed sulfur-bearing species show similar abundances both in MM1a and MM1b, whereas the methanol and saturated species show significant abundance enhancement toward MM1b, by about an order of magnitude, compared to MM1a.

  13. A MID-INFRARED IMAGING SURVEY OF SUBMILLIMETER-SELECTED GALAXIES WITH THE SPITZER SPACE TELESCOPE

    International Nuclear Information System (INIS)

    Hainline, Laura J.; Blain, A. W.; Smail, Ian; Frayer, D. T.; Chapman, S. C.; Ivison, R. J.; Alexander, D. M.

    2009-01-01

    We present Spitzer-IRAC and MIPS mid-IR observations of a sample of 73 radio-detected submillimeter-selected galaxies (SMGs) with spectroscopic redshifts, the largest such sample published to date. From our data, we find that IRAC colors of SMGs are much more uniform as compared with rest-frame UV and optical colors, and z>1.5 SMGs tend to be redder in their mid-IR colors than both field galaxies and lower-z SMGs. However, the IRAC colors of the SMGs overlap those of field galaxies sufficiently that color-magnitude and color-color selection criteria suggested in the literature to identify SMG counterparts produce ambiguous counterparts within an 8'' radius in 20%-35% of cases. We use a rest-frame J-H versus H-K color-color diagram and a S 24 /S 8.0 versus S 8.0 /S 4.5 color-color diagram to determine that 13%-19% of our sample are likely to contain active galactic nuclei which dominate their mid-IR emission. We observe in the rest-frame JHK colors of our sample that the rest-frame near-IR emission of SMGs does not resemble that of the compact nuclear starburst observed in local ultraluminous IR galaxies and is consistent with more widely distributed star formation. We take advantage of the fact that many high-z galaxy populations selected at different wavelengths are detected by Spitzer to carry out a brief comparison of mid-IR properties of SMGs to UV-selected high-z galaxies, 24 μm-selected galaxies, and high-z radio galaxies, and find that SMGs have mid-IR fluxes and colors which are consistent with being more massive and more reddened than UV-selected galaxies, while the IRAC colors of SMGs are most similar to powerful high-z radio galaxies.

  14. SUBMILLIMETER ARRAY AND SPITZER OBSERVATIONS OF BOK GLOBULE CB 17: A CANDIDATE FIRST HYDROSTATIC CORE?

    Energy Technology Data Exchange (ETDEWEB)

    Chen Xuepeng; Arce, Hector G.; Dunham, Michael M. [Department of Astronomy, Yale University, Box 208101, New Haven, CT 06520-8101 (United States); Zhang Qizhou; Bourke, Tyler L. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Launhardt, Ralf; Schmalzl, Markus; Henning, Thomas, E-mail: xuepeng.chen@yale.edu [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany)

    2012-06-01

    We present high angular resolution Submillimeter Array (SMA) and Spitzer observations toward the Bok globule CB 17. SMA 1.3 mm dust continuum images reveal within CB 17 two sources with an angular separation of {approx}21'' ({approx}5250 AU at a distance of {approx}250 pc). The northwestern continuum source, referred to as CB 17 IRS, dominates the infrared emission in the Spitzer images, drives a bipolar outflow extending in the northwest-southeast direction, and is classified as a low-luminosity Class 0/I transition object (L{sub bol} {approx} 0.5 L{sub Sun }). The southeastern continuum source, referred to as CB 17 MMS, has faint dust continuum emission in the SMA 1.3 mm observations ({approx}6{sigma} detection; {approx}3.8 mJy), but is not detected in the deep Spitzer infrared images at wavelengths from 3.6 to 70 {mu}m. Its bolometric luminosity and temperature, estimated from its spectral energy distribution, are {<=}0.04 L{sub Sun} and {<=}16 K, respectively. The SMA CO (2-1) observations suggest that CB 17 MMS may drive a low-velocity molecular outflow ({approx}2.5 km s{sup -1}), extending in the east-west direction. Comparisons with prestellar cores and Class 0 protostars suggest that CB 17 MMS is more evolved than prestellar cores but less evolved than Class 0 protostars. The observed characteristics of CB 17 MMS are consistent with the theoretical predictions from radiative/magnetohydrodynamical simulations of a first hydrostatic core, but there is also the possibility that CB 17 MMS is an extremely low luminosity protostar deeply embedded in an edge-on circumstellar disk. Further observations are needed to study the properties of CB 17 MMS and to address more precisely its evolutionary stage.

  15. High resolution phoswich gamma-ray imager utilizing monolithic MPPC arrays with submillimeter pixelized crystals

    International Nuclear Information System (INIS)

    Kato, T; Kataoka, J; Nakamori, T; Kishimoto, A; Yamamoto, S; Sato, K; Ishikawa, Y; Yamamura, K; Kawabata, N; Ikeda, H; Kamada, K

    2013-01-01

    We report the development of a high spatial resolution tweezers-type coincidence gamma-ray camera for medical imaging. This application consists of large-area monolithic Multi-Pixel Photon Counters (MPPCs) and submillimeter pixelized scintillator matrices. The MPPC array has 4 × 4 channels with a three-side buttable, very compact package. For typical operational gain of 7.5 × 10 5 at + 20 °C, gain fluctuation over the entire MPPC device is only ± 5.6%, and dark count rates (as measured at the 1 p.e. level) amount to ≤ 400 kcps per channel. We selected Ce-doped (Lu,Y) 2 (SiO 4 )O (Ce:LYSO) and a brand-new scintillator, Ce-doped Gd 3 Al 2 Ga 3 O 12 (Ce:GAGG) due to their high light yield and density. To improve the spatial resolution, these scintillators were fabricated into 15 × 15 matrices of 0.5 × 0.5 mm 2 pixels. The Ce:LYSO and Ce:GAGG scintillator matrices were assembled into phosphor sandwich (phoswich) detectors, and then coupled to the MPPC array along with an acrylic light guide measuring 1 mm thick, and with summing operational amplifiers that compile the signals into four position-encoded analog outputs being used for signal readout. Spatial resolution of 1.1 mm was achieved with the coincidence imaging system using a 22 Na point source. These results suggest that the gamma-ray imagers offer excellent potential for applications in high spatial medical imaging.

  16. Functional Connectivity of Resting Hemodynamic Signals in Submillimeter Orientation Columns of the Visual Cortex.

    Science.gov (United States)

    Vasireddi, Anil K; Vazquez, Alberto L; Whitney, David E; Fukuda, Mitsuhiro; Kim, Seong-Gi

    2016-09-07

    Resting-state functional magnetic resonance imaging has been increasingly used for examining connectivity across brain regions. The spatial scale by which hemodynamic imaging can resolve functional connections at rest remains unknown. To examine this issue, deoxyhemoglobin-weighted intrinsic optical imaging data were acquired from the visual cortex of lightly anesthetized ferrets. The neural activity of orientation domains, which span a distance of 0.7-0.8 mm, has been shown to be correlated during evoked activity and at rest. We performed separate analyses to assess the degree to which the spatial and temporal characteristics of spontaneous hemodynamic signals depend on the known functional organization of orientation columns. As a control, artificial orientation column maps were generated. Spatially, resting hemodynamic patterns showed a higher spatial resemblance to iso-orientation maps than artificially generated maps. Temporally, a correlation analysis was used to establish whether iso-orientation domains are more correlated than orthogonal orientation domains. After accounting for a significant decrease in correlation as a function of distance, a small but significant temporal correlation between iso-orientation domains was found, which decreased with increasing difference in orientation preference. This dependence was abolished when using artificially synthetized orientation maps. Finally, the temporal correlation coefficient as a function of orientation difference at rest showed a correspondence with that calculated during visual stimulation suggesting that the strength of resting connectivity is related to the strength of the visual stimulation response. Our results suggest that temporal coherence of hemodynamic signals measured by optical imaging of intrinsic signals exists at a submillimeter columnar scale in resting state.

  17. The rest-frame submillimeter spectrum of high-redshift, dusty, star-forming galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Spilker, J. S.; Marrone, D. P. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Aguirre, J. E. [University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Aravena, M. [European Southern Observatory, Alonso de Cordova 3107, Casilla 19001 Vitacura Santiago (Chile); Ashby, M. L. N. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Béthermin, M. [Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu-CNRS-Université Paris Diderot, CEA-Saclay, Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Bradford, C. M. [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Bothwell, M. S. [Cavendish Laboratory, University of Cambridge, JJ Thompson Ave, Cambridge CB3 0HA (United Kingdom); Brodwin, M. [Department of Physics and Astronomy, University of Missouri, 5110 Rockhill Road, Kansas City, MO 64110 (United States); Carlstrom, J. E.; Crawford, T. M. [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Chapman, S. C. [Dalhousie University, Halifax, Nova Scotia (Canada); De Breuck, C.; Gullberg, B. [European Southern Observatory, Karl Schwarzschild Straße 2, D-85748 Garching (Germany); Fassnacht, C. D. [Department of Physics, University of California, One Shields Avenue, Davis, CA 95616 (United States); Gonzalez, A. H. [Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States); Greve, T. R. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Hezaveh, Y. [Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec H3A 2T8 (Canada); Holzapfel, W. L., E-mail: jspilker@as.arizona.edu [Department of Physics, University of California, Berkeley, CA 94720 (United States); and others

    2014-04-20

    We present the average rest-frame spectrum of high-redshift dusty, star-forming galaxies from 250 to 770 GHz. This spectrum was constructed by stacking Atacama Large Millimeter/submillimeter Array (ALMA) 3 mm spectra of 22 such sources discovered by the South Pole Telescope and spanning z = 2.0-5.7. In addition to multiple bright spectral features of {sup 12}CO, [C I], and H{sub 2}O, we also detect several faint transitions of {sup 13}CO, HCN, HNC, HCO{sup +}, and CN, and use the observed line strengths to characterize the typical properties of the interstellar medium of these high-redshift starburst galaxies. We find that the {sup 13}CO brightness in these objects is comparable to that of the only other z > 2 star-forming galaxy in which {sup 13}CO has been observed. We show that the emission from the high-critical density molecules HCN, HNC, HCO{sup +}, and CN is consistent with a warm, dense medium with T {sub kin} ∼ 55 K and n{sub H{sub 2}}≳10{sup 5.5} cm{sup –3}. High molecular hydrogen densities are required to reproduce the observed line ratios, and we demonstrate that alternatives to purely collisional excitation are unlikely to be significant for the bulk of these systems. We quantify the average emission from several species with no individually detected transitions, and find emission from the hydride CH and the linear molecule CCH for the first time at high redshift, indicating that these molecules may be powerful probes of interstellar chemistry in high-redshift systems. These observations represent the first constraints on many molecular species with rest-frame transitions from 0.4 to 1.2 mm in star-forming systems at high redshift, and will be invaluable in making effective use of ALMA in full science operations.

  18. GaN transistors for efficient power conversion

    CERN Document Server

    Lidow, Alex; de Rooij, Michael; Reusch, David

    2014-01-01

    The first edition of GaN Transistors for Efficient Power Conversion was self-published by EPC in 2012, and is currently the only other book to discuss GaN transistor technology and specific applications for the technology. More than 1,200 copies of the first edition have been sold through Amazon or distributed to selected university professors, students and potential customers, and a simplified Chinese translation is also available. The second edition has expanded emphasis on applications for GaN transistors and design considerations. This textbook provides technical and application-focused i

  19. Large magnetocurrents in double-barrier tunneling transistors

    International Nuclear Information System (INIS)

    Lee, J.H.; Jun, K.-I.; Shin, K.-H.; Park, S.Y.; Hong, J.K.; Rhie, K.; Lee, B.C.

    2005-01-01

    Magnetic tunneling transistors (MTT) with double tunneling barriers are fabricated. The structure of the transistor is AFM/FM/I/FM/I/FM/AFM, and ferromagnetic layers serve as the emitter, base and collector. This double-barrier tunneling transistor (DBTT) has an advantage of controlling the potential between the base and collector, compared to the Schottky-barrier-based base and collector of MTT. We found that the collector current density of DBTT is at least 10 3 times larger than that of conventional MTT, since tunneling through AlO x barrier provides much larger current density than that through Schottky barrier

  20. Organic semiconductors for organic field-effect transistors

    International Nuclear Information System (INIS)

    Yamashita, Yoshiro

    2009-01-01

    The advantages of organic field-effect transistors (OFETs), such as low cost, flexibility and large-area fabrication, have recently attracted much attention due to their electronic applications. Practical transistors require high mobility, large on/off ratio, low threshold voltage and high stability. Development of new organic semiconductors is key to achieving these parameters. Recently, organic semiconductors have been synthesized showing comparable mobilities to amorphous-silicon-based FETs. These materials make OFETs more attractive and their applications have been attempted. New organic semiconductors resulting in high-performance FET devices are described here and the relationship between transistor characteristics and chemical structure is discussed. (topical review)

  1. Organic semiconductors for organic field-effect transistors

    Directory of Open Access Journals (Sweden)

    Yoshiro Yamashita

    2009-01-01

    Full Text Available The advantages of organic field-effect transistors (OFETs, such as low cost, flexibility and large-area fabrication, have recently attracted much attention due to their electronic applications. Practical transistors require high mobility, large on/off ratio, low threshold voltage and high stability. Development of new organic semiconductors is key to achieving these parameters. Recently, organic semiconductors have been synthesized showing comparable mobilities to amorphous-silicon-based FETs. These materials make OFETs more attractive and their applications have been attempted. New organic semiconductors resulting in high-performance FET devices are described here and the relationship between transistor characteristics and chemical structure is discussed.

  2. Transistor regenerative spectrometer for 14N nuclear quadrupole resonance study

    International Nuclear Information System (INIS)

    Anferov, V.P.; Mikhal'kov, V.M.

    1981-01-01

    Improvement of the Robinson transducer for investigations of nuclear quadrupole resonance (NQR) in 14 N is described. Amplifier of the suggested transducer is made using p-n field effect transistor and small-noise SHF bipolar transistor. Such a circuit permits to obtain optimal relation between input resistance, low-frequency noises and transconductance which provides uniform gain of the transducer in the frequency range of 0.6-12 MHz and permits to construct a transistor spectrometer of NQR not yielding to a lamp spectrometer in sensitivity [ru

  3. Observation of strong reflection of electron waves exiting a ballistic channel at low energy

    Energy Technology Data Exchange (ETDEWEB)

    Vaz, Canute I.; Campbell, Jason P.; Ryan, Jason T.; Gundlach, David; Cheung, Kin. P., E-mail: Kin.Cheung@NIST.gov [National Institute of Standards and Technology, Gaithersburg, MD 20899-8120 (United States); Liu, Changze [National Institute of Standards and Technology, Gaithersburg, MD 20899-8120 (United States); Institute of Microelectronics, Peking University, Beijing 100871 (China); Southwick, Richard G. [National Institute of Standards and Technology, Gaithersburg, MD 20899-8120 (United States); IBM Research, Albany, NY 12205 (United States); Oates, Anthony S. [Taiwan Semiconductor Manufacturing Corporation, Hsinchu 30844, Taiwan (China); Huang, Ru [Institute of Microelectronics, Peking University, Beijing 100871 (China)

    2016-06-15

    Wave scattering by a potential step is a ubiquitous concept. Thus, it is surprising that theoretical treatments of ballistic transport in nanoscale devices, from quantum point contacts to ballistic transistors, assume no reflection even when the potential step is encountered upon exiting the device. Experiments so far seem to support this even if it is not clear why. Here we report clear evidence of coherent reflection when electron wave exits the channel of a nanoscale transistor and when the electron energy is low. The observed behavior is well described by a simple rectangular potential barrier model which the Schrodinger’s equation can be solved exactly. We can explain why reflection is not observed in most situations but cannot be ignored in some important situations. Our experiment also represents a direct measurement of electron injection velocity - a critical quantity in nanoscale transistors that is widely considered not measurable.

  4. Direct coupled amplifiers using field effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Fowler, E P [Control and Instrumentation Division, Atomic Energy Establishment, Winfrith, Dorchester, Dorset (United Kingdom)

    1964-03-15

    The concept of the uni-polar field effect transistor (P.E.T.) was known before the invention of the bi-polar transistor but it is only recently that they have been made commercially. Being produced as yet only in small quantities, their price imposes a restriction on use to circuits where their peculiar properties can be exploited to the full. One such application is described here where the combination of low voltage drift and relatively low input leakage current are necessarily used together. One of the instruments used to control nuclear reactors has a logarithmic response to the mean output current from a polarised ionisation chamber. The logarithmic signal is then differentiated electrically, the result being displayed on a meter calibrated to show the reactor divergence or doubling time. If displayed in doubling time the scale is calibrated reciprocally. Because of the wide range obtained in the logarithmic section and the limited supply voltage, an output of 1 volt per decade change in ionisation current is used. Differentiating this gives a current of 1.5 x 10{sup -8} A for p.s.D. (20 sec. doubling time) in the differentiating amplifier. To overcome some of the problems of noise due to statistical variations in input current, the circuit design necessitates a resistive path to ground at the amplifier input of 20 M.ohms. A schematic diagram is shown. 1. It is evident that a zero drift of 1% can be caused by a leakage current of 1.5 x 10{sup -10} A or an offset voltage of 3 mV at the amplifier input. Although the presently used electrometer valve is satisfactory from the point of view of grid current, there have been sudden changes in grid to grid voltage (the valve is a double triode) of up to 10 m.V. It has been found that a pair of F.E.T's. can be used to replace the electrometer valve so long as care is taken in correct balance of the two devices. An investigation has been made into the characteristics of some fourteen devices to see whether those with

  5. Calcium waves.

    Science.gov (United States)

    Jaffe, Lionel F

    2008-04-12

    Waves through living systems are best characterized by their speeds at 20 degrees C. These speeds vary from those of calcium action potentials to those of ultraslow ones which move at 1-10 and/or 10-20 nm s(-1). All such waves are known or inferred to be calcium waves. The two classes of calcium waves which include ones with important morphogenetic effects are slow waves that move at 0.2-2 microm s(-1) and ultraslow ones. Both may be propagated by cycles in which the entry of calcium through the plasma membrane induces subsurface contraction. This contraction opens nearby stretch-sensitive calcium channels. Calcium entry through these channels propagates the calcium wave. Many slow waves are seen as waves of indentation. Some are considered to act via cellular peristalsis; for example, those which seem to drive the germ plasm to the vegetal pole of the Xenopus egg. Other good examples of morphogenetic slow waves are ones through fertilizing maize eggs, through developing barnacle eggs and through axolotl embryos during neural induction. Good examples of ultraslow morphogenetic waves are ones during inversion in developing Volvox embryos and across developing Drosophila eye discs. Morphogenetic waves may be best pursued by imaging their calcium with aequorins.

  6. Wave turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Nazarenko, Sergey [Warwick Univ., Coventry (United Kingdom). Mathematics Inst.

    2011-07-01

    Wave Turbulence refers to the statistical theory of weakly nonlinear dispersive waves. There is a wide and growing spectrum of physical applications, ranging from sea waves, to plasma waves, to superfluid turbulence, to nonlinear optics and Bose-Einstein condensates. Beyond the fundamentals the book thus also covers new developments such as the interaction of random waves with coherent structures (vortices, solitons, wave breaks), inverse cascades leading to condensation and the transitions between weak and strong turbulence, turbulence intermittency as well as finite system size effects, such as ''frozen'' turbulence, discrete wave resonances and avalanche-type energy cascades. This book is an outgrow of several lectures courses held by the author and, as a result, written and structured rather as a graduate text than a monograph, with many exercises and solutions offered along the way. The present compact description primarily addresses students and non-specialist researchers wishing to enter and work in this field. (orig.)

  7. Radiation effects on junction field-effect transistors (JFETS), MOSFETs, and bipolar transistors, as related to SSC circuit design

    International Nuclear Information System (INIS)

    Kennedy, E.J.; Alley, G.T.; Britton, C.L. Jr.; Skubic, P.L.; Gray, B.; Wu, A.

    1990-01-01

    Some results of radiation effects on selected junction field-effect transistors, MOS field-effect transistors, and bipolar junction transistors are presented. The evaluations include dc parameters, as well as capacitive variations and noise evaluations. The tests are made at the low current and voltage levels (in particular, at currents ≤1 mA) that are essential for the low-power regimes required by SSC circuitry. Detailed noise data are presented both before and after 5-Mrad (gamma) total-dose exposure. SPICE radiation models for three high-frequency bipolar processes are compared for a typical charge-sensitive preamplifier

  8. Highly Specific and Sensitive Fluorescent Nanoprobes for Image-Guided Resection of Sub-Millimeter Peritoneal Tumors.

    Science.gov (United States)

    Colby, Aaron H; Berry, Samantha M; Moran, Ann M; Pasion, Kristine Amber; Liu, Rong; Colson, Yolonda L; Ruiz-Opazo, Nelson; Grinstaff, Mark W; Herrera, Victoria L M

    2017-02-28

    A current challenge in the treatment of peritoneal carcinomatosis is the inability to detect, visualize, and resect small or microscopic tumors of pancreatic, ovarian, or mesothelial origin. In these diseases, the completeness of primary tumor resection is directly correlated with patient survival, and hence, identifying small sub-millimeter tumors (i.e., disseminated disease) is critical. Thus, new imaging techniques and probes are needed to improve cytoreductive surgery and patient outcomes. Highly fluorescent rhodamine-labeled expansile nanoparticles (HFR-eNPs) are described for use as a visual aid during cytoreductive surgery of pancreatic carcinomatosis. The covalent incorporation of rhodamine into ∼30 nm eNPs increases the fluorescent signal compared to free rhodamine, thereby affording a brighter and more effective probe than would be achieved by a single rhodamine molecule. Using the intraperitoneal route of administration, HFR-eNPs localize to regions of large (∼1 cm), sub-centimeter, and sub-millimeter intraperitoneal tumor in three different animal models, including pancreatic, mesothelioma, and ovarian carcinoma. Tumoral localization of the HFR-eNPs depends on both the material property (i.e., eNP polymer) as well as the surface chemistry (anionic surfactant vs PEGylated noncharged surfactant). In a rat model of pancreatic carcinomatosis, HFR-eNP identification of tumor is validated against gold-standard histopathological analysis to reveal that HFR-eNPs possess high specificity (99%) and sensitivity (92%) for tumors, in particular, sub-centimeter and microscopic sub-millimeter tumors, with an overall accuracy of 95%. Finally, as a proof-of-concept, HFR-eNPs are used to guide the resection of pancreatic tumors in a rat model of peritoneal carcinomatosis.

  9. PHYSICAL PROPERTIES AND MORPHOLOGY OF A NEWLY IDENTIFIED COMPACT z = 4.04 LENSED SUBMILLIMETER GALAXY IN ABELL 2218

    International Nuclear Information System (INIS)

    Knudsen, Kirsten K.; Kneib, Jean-Paul; Richard, Johan; Petitpas, Glen; Egami, Eiichi

    2010-01-01

    We present the identification of a bright submillimeter (submm) source, SMM J163555.5+661300, detected in the lensing cluster Abell 2218, for which we have accurately determined the position using observations from the Submillimeter Array (SMA). The identified optical counterpart has a spectroscopic redshift of z = 4.044 ± 0.001 if we attribute the single emission line detected at λ = 6140 A to Lyα. This redshift identification is in good agreement with the optical/near-infrared photometric redshift as well as the submm flux ratio S 450 /S 850 ∼ 1.6, the radio-submm flux ratio S 1.4 /S 850 24 /S 850 12 L sun , which implies a star formation rate (SFR) of 230 M sun yr -1 . This makes it the lowest-luminosity submillimeter galaxy (SMG) known at z>4 to date. Previous CO(4-3) emission line observations yielded a non-detection, for which we derived an upper limit of the CO line luminosity of L CO ' = 0.3x10 10 K km s -1 pc -2 , which is not inconsistent with the L ' CO -L FIR relation for starburst galaxies. The best-fit model to the optical and near-infrared photometry give a stellar population with an age of 1.4 Gyr and a stellar mass of 1.6 x 10 10 M sun . The optical morphology is compact and in the source plane the galaxy has an extent of ∼6 x 3 kpc with individual star-forming knots of sun yr -1 kpc 2 . The redshift of J163556 extends the redshift distribution of faint, lensed SMGs, and we find no evidence that these have a different redshift distribution than bright SMGs.

  10. Gamma dose rate effect on JFET transistors

    International Nuclear Information System (INIS)

    Assaf, J.

    2011-04-01

    The effect of Gamma dose rate on JFET transistors is presented. The irradiation was accomplished at the following available dose rates: 1, 2.38, 5, 10 , 17 and 19 kGy/h at a constant dose of 600 kGy. A non proportional relationship between the noise and dose rate in the medium range (between 2.38 and 5 kGy/h) was observed. While in the low and high ranges, the noise was proportional to the dose rate as the case of the dose effect. This may be explained as follows: the obtained result is considered as the yield of a competition between many reactions and events which are dependent on the dose rate. At a given values of that events parameters, a proportional or a non proportional dose rate effects are generated. No dependence effects between the dose rate and thermal annealing recovery after irradiation was observed . (author)

  11. Tin oxide transparent thin-film transistors

    International Nuclear Information System (INIS)

    Presley, R E; Munsee, C L; Park, C-H; Hong, D; Wager, J F; Keszler, D A

    2004-01-01

    A SnO 2 transparent thin-film transistor (TTFT) is demonstrated. The SnO 2 channel layer is deposited by RF magnetron sputtering and then rapid thermal annealed in O 2 at 600 deg. C. The TTFT is highly transparent, and enhancement-mode behaviour is achieved by employing a very thin channel layer (10-20 nm). Maximum field-effect mobilities of 0.8 cm 2 V -1 s -1 and 2.0 cm 2 V -1 s -1 are obtained for enhancement- and depletion-mode devices, respectively. The transparent nature and the large drain current on-to-off ratio of 10 5 associated with the enhancement-mode behaviour of these devices may prove useful for novel gas-sensor applications

  12. Moving towards the magnetoelectric graphene transistor

    International Nuclear Information System (INIS)

    Cao, Shi; Xiao, Zhiyong; Kwan, Chun-Pui; Zhang, Kai; Bird, Jonathan P.

    2017-01-01

    Here, the interfacial charge transfer between mechanically exfoliated few-layer graphene and Cr 2 O 3 (0001) surfaces has been investigated. Electrostatic force microscopy and Kelvin probe force microscopy studies point to hole doping of few-layer graphene, with up to a 150 meV shift in the Fermi level, an aspect that is confirmed by Raman spectroscopy. Density functional theory calculations furthermore confirm the p-type nature of the graphene/chromia interface and suggest that the chromia is able to induce a significant carrier spin polarization in the graphene layer. A large magnetoelectrically controlled magneto-resistance can therefore be anticipated in transistor structures based on this system, a finding important for developing graphene-based spintronic applications.

  13. SiC for microwave power transistors

    Energy Technology Data Exchange (ETDEWEB)

    Sriram, S.; Siergiej, R.R.; Clarke, R.C.; Agarwal, A.K.; Brandt, C.D. [Northrop Grumman Sci. and Technol. Center, Pittsburgh, PA (United States)

    1997-07-16

    The advantages of SiC for high power, microwave devices are discussed. The design considerations, fabrication, and experimental results are described for SiC MESFETs and SITs. The highest reported f{sub max} for a 0.5 {mu}m MESFET using semi-insulating 4H-SiC is 42 GHz. These devices also showed a small signal gain of 5.1 dB at 20 GHz. Other 4H-SiC MESFETs have shown a power density of 3.3 W/mm at 850 MHz. The largest SiC power transistor reported is a 450 W SIT measured at 600 MHz. The power output density of this SIT is 2.5 times higher than that of comparable silicon devices. SITs have been designed to operate as high as 3.0 GHz, with a 3 cm periphery part delivering 38 W of output power. (orig.) 28 refs.

  14. Metal nanoparticle film-based room temperature Coulomb transistor.

    Science.gov (United States)

    Willing, Svenja; Lehmann, Hauke; Volkmann, Mirjam; Klinke, Christian

    2017-07-01

    Single-electron transistors would represent an approach to developing less power-consuming microelectronic devices if room temperature operation and industry-compatible fabrication were possible. We present a concept based on stripes of small, self-assembled, colloidal, metal nanoparticles on a back-gate device architecture, which leads to well-defined and well-controllable transistor characteristics. This Coulomb transistor has three main advantages. By using the scalable Langmuir-Blodgett method, we combine high-quality chemically synthesized metal nanoparticles with standard lithography techniques. The resulting transistors show on/off ratios above 90%, reliable and sinusoidal Coulomb oscillations, and room temperature operation. Furthermore, this concept allows for versatile tuning of the device properties such as Coulomb energy gap and threshold voltage, as well as period, position, and strength of the oscillations.

  15. Metal nanoparticle film–based room temperature Coulomb transistor

    Science.gov (United States)

    Willing, Svenja; Lehmann, Hauke; Volkmann, Mirjam; Klinke, Christian

    2017-01-01

    Single-electron transistors would represent an approach to developing less power–consuming microelectronic devices if room temperature operation and industry-compatible fabrication were possible. We present a concept based on stripes of small, self-assembled, colloidal, metal nanoparticles on a back-gate device architecture, which leads to well-defined and well-controllable transistor characteristics. This Coulomb transistor has three main advantages. By using the scalable Langmuir-Blodgett method, we combine high-quality chemically synthesized metal nanoparticles with standard lithography techniques. The resulting transistors show on/off ratios above 90%, reliable and sinusoidal Coulomb oscillations, and room temperature operation. Furthermore, this concept allows for versatile tuning of the device properties such as Coulomb energy gap and threshold voltage, as well as period, position, and strength of the oscillations. PMID:28740864

  16. Light programmable organic transistor memory device based on hybrid dielectric

    Science.gov (United States)

    Ren, Xiaochen; Chan, Paddy K. L.

    2013-09-01

    We have fabricated the transistor memory devices based on SiO2 and polystyrene (PS) hybrid dielectric. The trap states densities with different semiconductors have been investigated and a maximum 160V memory window between programming and erasing is realized. For DNTT based transistor, the trapped electron density is limited by the number of mobile electrons in semiconductor. The charge transport mechanism is verified by light induced Vth shift effect. Furthermore, in order to meet the low operating power requirement of portable electronic devices, we fabricated the organic memory transistor based on AlOx/self-assembly monolayer (SAM)/PS hybrid dielectric, the effective capacitance of hybrid dielectric is 210 nF cm-2 and the transistor can reach saturation state at -3V gate bias. The memory window in transfer I-V curve is around 1V under +/-5V programming and erasing bias.

  17. Laser-Printed Organic Thin-Film Transistors

    KAUST Repository

    Diemer, Peter J.; Harper, Angela F.; Niazi, Muhammad Rizwan; Petty, Anthony J.; Anthony, John E.; Amassian, Aram; Jurchescu, Oana D.

    2017-01-01

    their incorporation in large-scale manufacturing processes. Here, the first ever organic thin-film transistor fabricated with an electrophotographic laser printing process using a standard office laser printer is reported. This completely solvent-free additive

  18. Microwave field-efffect transistors theory, design, and application

    CERN Document Server

    Pengelly, Raymond

    1994-01-01

    This book covers the use of devices in microwave circuits and includes such topics as semiconductor theory and transistor performance, CAD considerations, intermodulation, noise figure, signal handling, S-parameter mapping, narrow- and broadband techniques, packaging and thermal considerations.

  19. Cylindrical Field Effect Transistor: A Full Volume Inversion Device

    KAUST Repository

    Fahad, Hossain M.

    2010-01-01

    inversion in the body. However, these devices are still limited by lithographic and processing challenges making them unsuitable for commercial production. This thesis explores a unique device structure called the CFET (Cylindrical Field Effect Transistors

  20. A nanoscale piezoelectric transformer for low-voltage transistors.

    Science.gov (United States)

    Agarwal, Sapan; Yablonovitch, Eli

    2014-11-12

    A novel piezoelectric voltage transformer for low-voltage transistors is proposed. Placing a piezoelectric transformer on the gate of a field-effect transistor results in the piezoelectric transformer field-effect transistor that can switch at significantly lower voltages than a conventional transistor. The piezoelectric transformer operates by using one piezoelectric to squeeze another piezoelectric to generate a higher output voltage than the input voltage. Multiple piezoelectrics can be used to squeeze a single piezoelectric layer to generate an even higher voltage amplification. Coupled electrical and mechanical modeling in COMSOL predicts a 12.5× voltage amplification for a six-layer piezoelectric transformer. This would lead to more than a 150× reduction in the power needed for communications.

  1. Field emission current from a junction field-effect transistor

    International Nuclear Information System (INIS)

    Monshipouri, Mahta; Abdi, Yaser

    2015-01-01

    Fabrication of a titanium dioxide/carbon nanotube (TiO 2 /CNT)-based transistor is reported. The transistor can be considered as a combination of a field emission transistor and a junction field-effect transistor. Using direct current plasma-enhanced chemical vapor deposition (DC-PECVD) technique, CNTs were grown on a p-typed (100)-oriented silicon substrate. The CNTs were then covered by TiO 2 nanoparticles 2–5 nm in size, using an atmospheric pressure CVD technique. In this device, TiO 2 /CNT junction is responsible for controlling the emission current. High on/off-current ratio and proper gate control are the most important advantages of device. A model based on Fowler–Nordheim equation is utilized for calculation of the emission current and the results are compared with experimental data. The effect of TiO 2 /CNT hetero-structure is also investigated, and well modeled

  2. Controlling charge current through a DNA based molecular transistor

    Energy Technology Data Exchange (ETDEWEB)

    Behnia, S., E-mail: s.behnia@sci.uut.ac.ir; Fathizadeh, S.; Ziaei, J.

    2017-01-05

    Molecular electronics is complementary to silicon-based electronics and may induce electronic functions which are difficult to obtain with conventional technology. We have considered a DNA based molecular transistor and study its transport properties. The appropriate DNA sequence as a central chain in molecular transistor and the functional interval for applied voltages is obtained. I–V characteristic diagram shows the rectifier behavior as well as the negative differential resistance phenomenon of DNA transistor. We have observed the nearly periodic behavior in the current flowing through DNA. It is reported that there is a critical gate voltage for each applied bias which above it, the electrical current is always positive. - Highlights: • Modeling a DNA based molecular transistor and studying its transport properties. • Choosing the appropriate DNA sequence using the quantum chaos tools. • Choosing the functional interval for voltages via the inverse participation ratio tool. • Detecting the rectifier and negative differential resistance behavior of DNA.

  3. Vertically aligned carbon nanotube field-effect transistors

    KAUST Repository

    Li, Jingqi; Zhao, Chao; Wang, Qingxiao; Zhang, Qiang; Wang, Zhihong; Zhang, Xixiang; Abutaha, Anas I.; Alshareef, Husam N.

    2012-01-01

    Vertically aligned carbon nanotube field-effect transistors (CNTFETs) have been developed using pure semiconducting carbon nanotubes. The source and drain were vertically stacked, separated by a dielectric, and the carbon nanotubes were placed

  4. Wavy channel transistor for area efficient high performance operation

    KAUST Repository

    Fahad, Hossain M.; Hussain, Aftab M.; Hussain, Muhammad Mustafa; Sevilla, Galo T.

    2013-01-01

    We report a wavy channel FinFET like transistor where the channel is wavy to increase its width without any area penalty and thereby increasing its drive current. Through simulation and experiments, we show the effectiveness of such device

  5. Molecular materials for organic field-effect transistors

    International Nuclear Information System (INIS)

    Mori, T

    2008-01-01

    Organic field-effect transistors are important applications of thin films of molecular materials. A variety of materials have been explored for improving the performance of organic transistors. The materials are conventionally classified as p-channel and n-channel, but not only the performance but also even the carrier polarity is greatly dependent on the combinations of organic semiconductors and electrode materials. In this review, particular emphasis is laid on multi-sulfur compounds such as tetrathiafulvalenes and metal dithiolates. These compounds are components of highly conducting materials such as organic superconductors, but are also used in organic transistors. The charge-transfer complexes are used in organic transistors as active layers as well as electrodes. (topical review)

  6. Low-frequency noise in single electron tunneling transistor

    DEFF Research Database (Denmark)

    Tavkhelidze, A.N.; Mygind, Jesper

    1998-01-01

    The noise in current biased aluminium single electron tunneling (SET) transistors has been investigated in the frequency range of 5 mHz ..., we find the same input charge noise, typically QN = 5 × 10–4 e/Hz1/2 at 10 Hz, with and without the HF shielding. At lower frequencies, the noise is due to charge trapping, and the voltage noise pattern superimposed on the V(Vg) curve (voltage across transistor versus gate voltage) strongly depends...... when ramping the junction voltage. Dynamic trapping may limit the high frequency applications of the SET transistor. Also reported on are the effects of rf irradiation and the dependence of the SET transistor noise on bias voltage. ©1998 American Institute of Physics....

  7. Group IV nanotube transistors for next generation ubiquitous computing

    KAUST Repository

    Fahad, Hossain M.; Hussain, Aftab M.; Sevilla, Galo T.; Banerjee, Sanjay K.; Hussain, Muhammad Mustafa

    2014-01-01

    Evolution in transistor technology from increasingly large power consuming single gate planar devices to energy efficient multiple gate non-planar ultra-narrow (< 20 nm) fins has enhanced the scaling trend to facilitate doubling performance. However

  8. Performance Enhancement of Power Transistors and Radiation effect

    International Nuclear Information System (INIS)

    Hassn, Th.A.A.

    2012-01-01

    The main objective of this scientific research is studying the characteristic of bipolar junction transistor device and its performance under radiation fields and temperature effect as a control element in many power circuits. In this work we present the results of experimental measurements and analytical simulation of gamma – radiation effects on the electrical characteristics and operation of power transistor types 2N3773, 2N3055(as complementary silicon power transistor are designed for general-purpose switching and amplifier applications), three samples of each type were irradiated by gamma radiation with doses, 1 K rad, 5 K rad, 10 K rad, 30 K rad, and 10 Mrad, the experimental data are utilized to establish an analytical relation between the total absorbed dose of gamma irradiation and corresponding to effective density of generated charge in the internal structure of transistor, the electrical parameters which can be measured to estimate the generated defects in the power transistor are current gain, collector current and collected emitter leakage current , these changes cause the circuit to case proper functioning. Collector current and transconductance of each device are calibrated as a function of irradiated dose. Also the threshold voltage and transistor gain can be affected and also calibrated as a function of dose. A silicon NPN power transistor type 2N3773 intended for general purpose applications, were used in this work. It was designed for medium current and high power circuits. Performance and characteristic were discusses under temperature and gamma radiation doses. Also the internal junction thermal system of the transistor represented in terms of a junction thermal resistance (Rjth). The thermal resistance changed by ΔRjth, due to the external intended, also due to the gamma doses intended. The final result from the model analysis reveals that the emitter-bias configuration is quite stable by resistance ratio RB/RE. Also the current

  9. The Transistor as Low Level Switch

    Energy Technology Data Exchange (ETDEWEB)

    Lyden, Anders

    1963-10-15

    The common collector transistor switch has in the on state with open emitter a certain offset voltage U{sub EK} {approx_equal} -kT/qB{sub N}. This expression is derived in a new, more physical way. It is further shown at which emitter current the current amplification factor B{sub N} should be measured to get a correct value for the above expression. The collector current I at zero collector voltage I{sub K} = I{sub 0}(exp(qU{sub E}/kT) - 1) extremely well. Substitution of I{sub EBO} and I{sub KBO} by I{sub 0} in Eber's and Moll's relations consequently improves these equations and the characteristics of the transistor switch can be better determined. At switching on and off transients appear across the switch. The influence of the 'spike' at switching off can be described by an current I{sub SPIKE} which is easy to calculate. I{sub SPIKE} is approximately dependent only on the base - emitter depletion layer capacitance and the chopper frequency f{sub 0}. Some compensated switches have lower drift than the drift in U{sub EK}. They may, for example, have a temperature drift < 0.2 {mu}V/deg C and a long time drift < 2 {mu}V/week. Some compensated switches also have I{sub SPIKE} < 10{sup -12} f{sub 0}A. The static offset current in the off state can easily be made < 10{sup -12} A.

  10. Schottky Barriers in Bilayer Phosphorene Transistors.

    Science.gov (United States)

    Pan, Yuanyuan; Dan, Yang; Wang, Yangyang; Ye, Meng; Zhang, Han; Quhe, Ruge; Zhang, Xiuying; Li, Jingzhen; Guo, Wanlin; Yang, Li; Lu, Jing

    2017-04-12

    It is unreliable to evaluate the Schottky barrier height (SBH) in monolayer (ML) 2D material field effect transistors (FETs) with strongly interacted electrode from the work function approximation (WFA) because of existence of the Fermi-level pinning. Here, we report the first systematical study of bilayer (BL) phosphorene FETs in contact with a series of metals with a wide work function range (Al, Ag, Cu, Au, Cr, Ti, Ni, and Pd) by using both ab initio electronic band calculations and quantum transport simulation (QTS). Different from only one type of Schottky barrier (SB) identified in the ML phosphorene FETs, two types of SBs are identified in BL phosphorene FETs: the vertical SB between the metallized and the intact phosphorene layer, whose height is determined from the energy band analysis (EBA); the lateral SB between the metallized and the channel BL phosphorene, whose height is determined from the QTS. The vertical SBHs show a better consistency with the lateral SBHs of the ML phosphorene FETs from the QTS compared than that of the popular WFA. Therefore, we develop a better and more general method than the WFA to estimate the lateral SBHs of ML semiconductor transistors with strongly interacted electrodes based on the EBA for its BL counterpart. In terms of the QTS, n-type lateral Schottky contacts are formed between BL phosphorene and Cr, Al, and Cu electrodes with electron SBH of 0.27, 0.31, and 0.32 eV, respectively, while p-type lateral Schottky contacts are formed between BL phosphorene and Pd, Ti, Ni, Ag, and Au electrodes with hole SBH of 0.11, 0.18, 0.19, 0.20, and 0.21 eV, respectively. The theoretical polarity and SBHs are in good agreement with available experiments. Our study provides an insight into the BL phosphorene-metal interfaces that are crucial for designing the BL phosphorene device.

  11. Retrieval of an ice water path over the ocean from ISMAR and MARSS millimeter and submillimeter brightness temperatures

    Directory of Open Access Journals (Sweden)

    M. Brath

    2018-02-01

    Full Text Available A neural-network-based retrieval method to determine the snow ice water path (SIWP, liquid water path (LWP, and integrated water vapor (IWV from millimeter and submillimeter brightness temperatures, measured by using airborne radiometers (ISMAR and MARSS, is presented. The neural networks were trained by using atmospheric profiles from the ICON numerical weather prediction (NWP model and by radiative transfer simulations using the Atmospheric Radiative Transfer Simulator (ARTS. The basic performance of the retrieval method was analyzed in terms of offset (bias and the median fractional error (MFE, and the benefit of using submillimeter channels was studied in comparison to pure microwave retrievals. The retrieval is offset-free for SIWP  > 0.01 kg m−2, LWP  > 0.1 kg m−2, and IWV  > 3 kg m−2. The MFE of SIWP decreases from 100 % at SIWP  =  0.01 kg m−2 to 20 % at SIWP  =  1 kg m−2 and the MFE of LWP from 100 % at LWP  = 0.05 kg m−2 to 30 % at LWP  =  1 kg m−2. The MFE of IWV for IWV  > 3 kg m−2 is 5 to 8 %. The SIWP retrieval strongly benefits from submillimeter channels, which reduce the MFE by a factor of 2, compared to pure microwave retrievals. The IWV and the LWP retrievals also benefit from submillimeter channels, albeit to a lesser degree. The retrieval was applied to ISMAR and MARSS brightness temperatures from FAAM flight B897 on 18 March 2015 of a precipitating frontal system west of the coast of Iceland. Considering the given uncertainties, the retrieval is in reasonable agreement with the SIWP, LWP, and IWV values simulated by the ICON NWP model for that flight. A comparison of the retrieved IWV with IWV from 12 dropsonde measurements shows an offset of 0.5 kg m−2 and an RMS difference of 0.8 kg m−2, showing that the retrieval of IWV is highly effective even under cloudy conditions.

  12. MM wave quasioptical SIS mixers

    International Nuclear Information System (INIS)

    Hu, Qing; Mears, C.A.; Richards, P.L.; Lloyd, F.L.

    1988-08-01

    We have tested the performance of planar SIS mixers with log-periodic antennas at near millimeter and submillimeter wave frequencies from 90 to 360 GHz. The large ωR/sub N/C product (/approximately/10 at 90 GHz) of our Nb/NbO/sub x//Pb-In-Au junctions requires an integrated inductive tuning element to resonate the junction capacitance at the operating frequencies. We have used two types of integrated tuning element, which were designed with the aid of measurements using a Fourier transform spectrometer. Preliminary results indicate that the tuning elements can give very good mixer performance up to at least 200 GHz. An inductive wire in parallel with a 5-junction array gives a minimum mixer noise temperature of 115K (DSB) at 90 GHz with a FWHM bandwidth of 8 GHz. An open-ended microstrip stub in parallel with a single junction, gives minimum mixer noise temperatures of 150 and 200K (DSB) near 90 and 180 GHz with FWHM bandwidths of 4 and 3 GHz, respectively. The relatively high mixer noise temperatures compared to those of waveguide SIS mixers in a similar frequency range are attributed mainly to the losses in our optical system, which is being improved. 13 refs., 6 figs., 1 tab

  13. Phase transition and field effect topological quantum transistor made of monolayer MoS2

    Science.gov (United States)

    Simchi, H.; Simchi, M.; Fardmanesh, M.; Peeters, F. M.

    2018-06-01

    We study topological phase transitions and topological quantum field effect transistor in monolayer molybdenum disulfide (MoS2) using a two-band Hamiltonian model. Without considering the quadratic (q 2) diagonal term in the Hamiltonian, we show that the phase diagram includes quantum anomalous Hall effect, quantum spin Hall effect, and spin quantum anomalous Hall effect regions such that the topological Kirchhoff law is satisfied in the plane. By considering the q 2 diagonal term and including one valley, it is shown that MoS2 has a non-trivial topology, and the valley Chern number is non-zero for each spin. We show that the wave function is (is not) localized at the edges when the q 2 diagonal term is added (deleted) to (from) the spin-valley Dirac mass equation. We calculate the quantum conductance of zigzag MoS2 nanoribbons by using the nonequilibrium Green function method and show how this device works as a field effect topological quantum transistor.

  14. Terahertz light-emitting graphene-channel transistor toward single-mode lasing

    Science.gov (United States)

    Yadav, Deepika; Tamamushi, Gen; Watanabe, Takayuki; Mitsushio, Junki; Tobah, Youssef; Sugawara, Kenta; Dubinov, Alexander A.; Satou, Akira; Ryzhii, Maxim; Ryzhii, Victor; Otsuji, Taiichi

    2018-03-01

    A distributed feedback dual-gate graphene-channel field-effect transistor (DFB-DG-GFET) was fabricated as a current-injection terahertz (THz) light-emitting laser transistor. We observed a broadband emission in a 1-7.6-THz range with a maximum radiation power of 10 μW as well as a single-mode emission at 5.2 THz with a radiation power of 0.1 μW both at 100 K when the carrier injection stays between the lower cutoff and upper cutoff threshold levels. The device also exhibited peculiar nonlinear threshold-like behavior with respect to the current-injection level. The LED-like broadband emission is interpreted as an amplified spontaneous THz emission being transcended to a single-mode lasing. Design constraints on waveguide structures for better THz photon field confinement with higher gain overlapping as well as DFB cavity structures with higher Q factors are also addressed towards intense, single-mode continuous wave THz lasing at room temperature.

  15. Investigations of Tunneling for Field Effect Transistors

    OpenAIRE

    Matheu, Peter

    2012-01-01

    Over 40 years of scaling dimensions for new and continuing product cycles has introduced new challenges for transistor design. As the end of the technology roadmap for semiconductors approaches, new device structures are being investigated as possible replacements for traditional metal-oxide-semiconductor field effect transistors (MOSFETs). Band-to-band tunneling (BTBT) in semiconductors, often viewed as an adverse effect of short channel lengths in MOSFETs, has been discussed as a promising ...

  16. All-Metallic Vertical Transistors Based on Stacked Dirac Materials

    OpenAIRE

    Wang, Yangyang; Ni, Zeyuan; Liu, Qihang; Quhe, Ruge; Zheng, Jiaxin; Ye, Meng; Yu, Dapeng; Shi, Junjie; Yang, Jinbo; Lu, Jing

    2014-01-01

    It is an ongoing pursuit to use metal as a channel material in a field effect transistor. All metallic transistor can be fabricated from pristine semimetallic Dirac materials (such as graphene, silicene, and germanene), but the on/off current ratio is very low. In a vertical heterostructure composed by two Dirac materials, the Dirac cones of the two materials survive the weak interlayer van der Waals interaction based on density functional theory method, and electron transport from the Dirac ...

  17. Progresses in organic field-effect transistors and molecular electronics

    Institute of Scientific and Technical Information of China (English)

    Wu Weiping; Xu Wei; Hu Wenping; Liu Yunqi; Zhu Daoben

    2006-01-01

    In the past years,organic semiconductors have been extensively investigated as electronic materials for organic field-effect transistors (OFETs).In this review,we briefly summarize the current status of organic field-effect transistors including materials design,device physics,molecular electronics and the applications of carbon nanotubes in molecular electronics.Future prospects and investigations required to improve the OFET performance are also involved.

  18. Modeling of charge transport in ion bipolar junction transistors.

    Science.gov (United States)

    Volkov, Anton V; Tybrandt, Klas; Berggren, Magnus; Zozoulenko, Igor V

    2014-06-17

    Spatiotemporal control of the complex chemical microenvironment is of great importance to many fields within life science. One way to facilitate such control is to construct delivery circuits, comprising arrays of dispensing outlets, for ions and charged biomolecules based on ionic transistors. This allows for addressability of ionic signals, which opens up for spatiotemporally controlled delivery in a highly complex manner. One class of ionic transistors, the ion bipolar junction transistors (IBJTs), is especially attractive for these applications because these transistors are functional at physiological conditions and have been employed to modulate the delivery of neurotransmitters to regulate signaling in neuronal cells. Further, the first integrated complementary ionic circuits were recently developed on the basis of these ionic transistors. However, a detailed understanding of the device physics of these transistors is still lacking and hampers further development of components and circuits. Here, we report on the modeling of IBJTs using Poisson's and Nernst-Planck equations and the finite element method. A two-dimensional model of the device is employed that successfully reproduces the main characteristics of the measurement data. On the basis of the detailed concentration and potential profiles provided by the model, the different modes of operation of the transistor are analyzed as well as the transitions between the different modes. The model correctly predicts the measured threshold voltage, which is explained in terms of membrane potentials. All in all, the results provide the basis for a detailed understanding of IBJT operation. This new knowledge is employed to discuss potential improvements of ion bipolar junction transistors in terms of miniaturization and device parameters.

  19. A Vertical Organic Transistor Architecture for Fast Nonvolatile Memory.

    Science.gov (United States)

    She, Xiao-Jian; Gustafsson, David; Sirringhaus, Henning

    2017-02-01

    A new device architecture for fast organic transistor memory is developed, based on a vertical organic transistor configuration incorporating high-performance ambipolar conjugated polymers and unipolar small molecules as the transport layers, to achieve reliable and fast programming and erasing of the threshold voltage shift in less than 200 ns. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Experimental Observation of Generation of Superradiance Pulses in the Process of Backscattering of Pump Wave on the Intense Electron Bunch

    CERN Document Server

    Ginzburg, N S; Denisov, G G; Rozental, R M; Sergeev, A; Zotova, I V

    2005-01-01

    Recently significant progress was archived in the generation of multimegawatt subnanosecond pulses in millimeter wave band utilizing the cyclotron and Cherenkov mechanisms of superradiance (SR) [1,2]. We study the novel mechanism of SR when the powerful pumping wave undergoes the stimulated back scattering on the intense electron bunch. Due to the Doppler up shift the radiation frequency can significantly exceed the frequency of the pumping wave. With the relativistic microwave generator as a pumping wave source such a mechanism can be used for generation of the powerful pulse radiation in the short millimeter and submillimeter wave bands. Experiments on the observation of the stimulated scattering in the superradiance regime were carried out at Institute of Electrophysics RAS with two synchronized accelerators. The 4 ns electron beam from the first accelerator is used for generation of the 38 GHz 100 MW pumping wave which subsequently scattered on the subnanosecond 250 keV 1 kA electron bunch produced by the...

  1. Optimizing switching frequency of the soliton transistor by numerical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Izadyar, S., E-mail: S_izadyar@yahoo.co [Department of Electronics, Khaje Nasir Toosi University of Technology, Shariati Ave., Tehran (Iran, Islamic Republic of); Niazzadeh, M.; Raissi, F. [Department of Electronics, Khaje Nasir Toosi University of Technology, Shariati Ave., Tehran (Iran, Islamic Republic of)

    2009-10-15

    In this paper, by numerical simulations we have examined different ways to increase the soliton transistor's switching frequency. Speed of the solitons in a soliton transistor depends on various parameters such as the loss of the junction, the applied bias current, and the transmission line characteristics. Three different ways have been examined; (i) decreasing the size of the transistor without losing transistor effect. (ii) Decreasing the amount of loss of the junction to increase the soliton speed. (iii) Optimizing the bias current to obtain maximum possible speed. We have obtained the shortest possible length to have at least one working soliton inside the transistor. The dimension of the soliton can be decreased by changing the inductance of the transmission line, causing a further decrease in the size of the transistor, however, a trade off between the size and the inductance is needed to obtain the optimum switching speed. Decreasing the amount of loss can be accomplished by increasing the characteristic tunneling resistance of the device, however, a trade off is again needed to make soliton and antisoliton annihilation possible. By increasing the bias current, the forces acting the solitons increases and so does their speed. Due to nonuniform application of bias current a self induced magnetic field is created which can result in creation of unwanted solitons. Optimum bias current application can result in larger bias currents and larger soliton speed. Simulations have provided us with such an arrangement of bias current paths.

  2. Optimizing switching frequency of the soliton transistor by numerical simulation

    International Nuclear Information System (INIS)

    Izadyar, S.; Niazzadeh, M.; Raissi, F.

    2009-01-01

    In this paper, by numerical simulations we have examined different ways to increase the soliton transistor's switching frequency. Speed of the solitons in a soliton transistor depends on various parameters such as the loss of the junction, the applied bias current, and the transmission line characteristics. Three different ways have been examined; (i) decreasing the size of the transistor without losing transistor effect. (ii) Decreasing the amount of loss of the junction to increase the soliton speed. (iii) Optimizing the bias current to obtain maximum possible speed. We have obtained the shortest possible length to have at least one working soliton inside the transistor. The dimension of the soliton can be decreased by changing the inductance of the transmission line, causing a further decrease in the size of the transistor, however, a trade off between the size and the inductance is needed to obtain the optimum switching speed. Decreasing the amount of loss can be accomplished by increasing the characteristic tunneling resistance of the device, however, a trade off is again needed to make soliton and antisoliton annihilation possible. By increasing the bias current, the forces acting the solitons increases and so does their speed. Due to nonuniform application of bias current a self induced magnetic field is created which can result in creation of unwanted solitons. Optimum bias current application can result in larger bias currents and larger soliton speed. Simulations have provided us with such an arrangement of bias current paths.

  3. Large scale electromechanical transistor with application in mass sensing

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Leisheng; Li, Lijie, E-mail: L.Li@swansea.ac.uk [Multidisciplinary Nanotechnology Centre, College of Engineering, Swansea University, Swansea SA2 8PP (United Kingdom)

    2014-12-07

    Nanomechanical transistor (NMT) has evolved from the single electron transistor, a device that operates by shuttling electrons with a self-excited central conductor. The unfavoured aspects of the NMT are the complexity of the fabrication process and its signal processing unit, which could potentially be overcome by designing much larger devices. This paper reports a new design of large scale electromechanical transistor (LSEMT), still taking advantage of the principle of shuttling electrons. However, because of the large size, nonlinear electrostatic forces induced by the transistor itself are not sufficient to drive the mechanical member into vibration—an external force has to be used. In this paper, a LSEMT device is modelled, and its new application in mass sensing is postulated using two coupled mechanical cantilevers, with one of them being embedded in the transistor. The sensor is capable of detecting added mass using the eigenstate shifts method by reading the change of electrical current from the transistor, which has much higher sensitivity than conventional eigenfrequency shift approach used in classical cantilever based mass sensors. Numerical simulations are conducted to investigate the performance of the mass sensor.

  4. Ultra-high gain diffusion-driven organic transistor

    Science.gov (United States)

    Torricelli, Fabrizio; Colalongo, Luigi; Raiteri, Daniele; Kovács-Vajna, Zsolt Miklós; Cantatore, Eugenio

    2016-01-01

    Emerging large-area technologies based on organic transistors are enabling the fabrication of low-cost flexible circuits, smart sensors and biomedical devices. High-gain transistors are essential for the development of large-scale circuit integration, high-sensitivity sensors and signal amplification in sensing systems. Unfortunately, organic field-effect transistors show limited gain, usually of the order of tens, because of the large contact resistance and channel-length modulation. Here we show a new organic field-effect transistor architecture with a gain larger than 700. This is the highest gain ever reported for organic field-effect transistors. In the proposed organic field-effect transistor, the charge injection and extraction at the metal–semiconductor contacts are driven by the charge diffusion. The ideal conditions of ohmic contacts with negligible contact resistance and flat current saturation are demonstrated. The approach is general and can be extended to any thin-film technology opening unprecedented opportunities for the development of high-performance flexible electronics. PMID:26829567

  5. Ultrashort Channel Length Black Phosphorus Field-Effect Transistors.

    Science.gov (United States)

    Miao, Jinshui; Zhang, Suoming; Cai, Le; Scherr, Martin; Wang, Chuan

    2015-09-22

    This paper reports high-performance top-gated black phosphorus (BP) field-effect transistors with channel lengths down to 20 nm fabricated using a facile angle evaporation process. By controlling the evaporation angle, the channel length of the transistors can be reproducibly controlled to be anywhere between 20 and 70 nm. The as-fabricated 20 nm top-gated BP transistors exhibit respectable on-state current (174 μA/μm) and transconductance (70 μS/μm) at a VDS of 0.1 V. Due to the use of two-dimensional BP as the channel material, the transistors exhibit relatively small short channel effects, preserving a decent on-off current ratio of 10(2) even at an extremely small channel length of 20 nm. Additionally, unlike the unencapsulated BP devices, which are known to be chemically unstable in ambient conditions, the top-gated BP transistors passivated by the Al2O3 gate dielectric layer remain stable without noticeable degradation in device performance after being stored in ambient conditions for more than 1 week. This work demonstrates the great promise of atomically thin BP for applications in ultimately scaled transistors.

  6. Implementation of Self-Bias Transistor on Voting Logic

    International Nuclear Information System (INIS)

    Harzawardi Hasim; Syirrazie Che Soh

    2014-01-01

    Study in the eld of digital integrated circuit (IC) already become common to the modern industrial. Day by day we have been introduced with new gadget that was developed based on transistor. This paper will study the implementation of self-bias transistor on voting logic. The self-bias transistor will connected both on pull-up network and pull-down network. On previous research, study on comparison of total number of transistors, time propagation delay, and frequency between NAND and NOR gate of voting logic. It's show, with the same number of transistor, NAND gate achieve high frequency and low time propagation delay compare to NOR gate. We extend this analysis by comparing the total number of transistor, time propagation delay, frequency and power dissipation between common NAND gate with self-bias NAND gate. Extensive LTSpice simulations were performed using IBM 90 nm CMOS(Complementary Metal Oxide Semiconductor) process technology. The result show self-bias voting NAND gate consumes 54 % less power dissipation, 43% slow frequency and 43 % high time propagation delay compare to common voting NAND gate. (author)

  7. GISMO, an ELT in space: a giant (30-m) far-infrared and submillimeter space observatory

    Science.gov (United States)

    Hawarden, Timothy G.; Johnstone, Callum; Johnstone, Graeme

    2004-07-01

    We describe GISMO, a concept for a 30-m class achromatic diffractive Fesnel space telescope operating in the far-IR and submillimeter from ~20 μm to ~700 μm. The concept is based on the precepts of Hyde (1999). It involves two units, the Lens and Instrument spacecraft, 3 km apart in a halo orbit around the Earth-Sun L2 point. The primary lens, L1, is a 30.1-m, 32-zone f/100 Fresnel lens, fabricated from ultra-high molecular-weight polyethylene (UHMW-PE). It is 1.0 to 3.4 mm thick (the features are 2.4 mm high for a "design wavelength" of 1.2 mm) and made in 5 strips linked by fabric hinges. It is stowed for launch by folding and rolling. It is deployed warm, unrolled by pneumatic or mechanical means, unfolded by carbon-fiber struts with Shape Memory Alloy hinges and stiffened until cold by a peripheral inflatable ring. Re-oriented edgeways-on to the Sun behind a 5-layer sunshade, L1 will then cool by radiation to space, approaching ~10K after 200 - 300 days. The low equilibrium temperature occurs because the lens is very thin and has a huge view factor to space but a small one to the sunshade. The Instrument spacecraft resembles a smaller, colder (~4K) version of the James Webb Space Telescope and shares features of a concept for the SAFIR mission. A near-field Ritchey-Chretien telescope with a 3-segment off-axis 6m x 3m primary acts as field lens, re-imaging L1 on a 30-cm f/1 Fresnel Corrector lens of equal and opposite dispersion, producing an achromatic beam which is directed to a focal plane equipped with imaging and spectroscopic instruments. The "design wavelength" of the telescope is 1.2 mm and it is employed at its second and higher harmonics. The shortest wavelength, ~20μm, is set by the transmission properties of the lens material (illustrated here) and determines the design tolerances of the optical system. The overall mass is estimated at ~5 tonnes and the stowed length around 14 m. Technical challenges and areas of uncertainty for the design concept

  8. High spatial resolution brain functional MRI using submillimeter balanced steady-state free precession acquisition

    International Nuclear Information System (INIS)

    Wu, Pei-Hsin; Chung, Hsiao-Wen; Tsai, Ping-Huei; Wu, Ming-Long; Chuang, Tzu-Chao; Shih, Yi-Yu; Huang, Teng-Yi

    2013-01-01

    Purpose: One of the technical advantages of functional magnetic resonance imaging (fMRI) is its precise localization of changes from neuronal activities. While current practice of fMRI acquisition at voxel size around 3 × 3 × 3 mm 3 achieves satisfactory results in studies of basic brain functions, higher spatial resolution is required in order to resolve finer cortical structures. This study investigated spatial resolution effects on brain fMRI experiments using balanced steady-state free precession (bSSFP) imaging with 0.37 mm 3 voxel volume at 3.0 T. Methods: In fMRI experiments, full and unilateral visual field 5 Hz flashing checkerboard stimulations were given to healthy subjects. The bSSFP imaging experiments were performed at three different frequency offsets to widen the coverage, with functional activations in the primary visual cortex analyzed using the general linear model. Variations of the spatial resolution were achieved by removing outerk-space data components. Results: Results show that a reduction in voxel volume from 3.44 × 3.44 × 2 mm 3 to 0.43 × 0.43 × 2 mm 3 has resulted in an increase of the functional activation signals from (7.7 ± 1.7)% to (20.9 ± 2.0)% at 3.0 T, despite of the threefold SNR decreases in the original images, leading to nearly invariant functional contrast-to-noise ratios (fCNR) even at high spatial resolution. Activation signals aligning nicely with gray matter sulci at high spatial resolution would, on the other hand, have possibly been mistaken as noise at low spatial resolution. Conclusions: It is concluded that the bSSFP sequence is a plausible technique for fMRI investigations at submillimeter voxel widths without compromising fCNR. The reduction of partial volume averaging with nonactivated brain tissues to retain fCNR is uniquely suitable for high spatial resolution applications such as the resolving of columnar organization in the brain

  9. 3C 220.3: A radio galaxy lensing a submillimeter galaxy

    Energy Technology Data Exchange (ETDEWEB)

    Haas, Martin; Westhues, Christian; Chini, Rolf [Astronomisches Institut, Ruhr Universität, Bochum (Germany); Leipski, Christian; Klaas, Ulrich; Meisenheimer, Klaus [Max-Planck-Institut für Astronomie, Heidelberg (Germany); Barthel, Peter; Koopmans, Léon V. E. [Kapteyn Astronomical Institute, University of Groningen (Netherlands); Wilkes, Belinda J.; Bussmann, R. Shane; Willner, S. P.; Ashby, Matthew L. N.; Kuraszkiewicz, Joanna [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Vegetti, Simona [Max-Planck-Institut für Astrophysik, Garching (Germany); Clements, David L. [Imperial College, London (United Kingdom); Fassnacht, Christopher D. [University of California, Davis, CA (United States); Horesh, Assaf [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA (United States); Lagattuta, David J. [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn (Australia); Stern, Daniel; Wylezalek, Dominika, E-mail: haas@astro.rub.de [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA (United States)

    2014-07-20

    Herschel Space Observatory photometry and extensive multiwavelength follow-up have revealed that the powerful radio galaxy (PRG) 3C 220.3 at z = 0.685 acts as a gravitational lens for a background submillimeter galaxy (SMG) at z = 2.221. At an observed wavelength of 1 mm, the SMG is lensed into three distinct images. In the observed near infrared, these images are connected by an arc of ∼1''.8 radius forming an Einstein half-ring centered near the radio galaxy. In visible light, only the arc is apparent. 3C 220.3 is the only known instance of strong galaxy-scale lensing by a PRG not located in a galaxy cluster and therefore it offers the potential to probe the dark matter content of the radio galaxy host. Lens modeling rejects a single lens, but two lenses centered on the radio galaxy host A and a companion B, separated by 1''.5, provide a fit consistent with all data and reveal faint candidates for the predicted fourth and fifth images. The model does not require an extended common dark matter halo, consistent with the absence of extended bright X-ray emission on our Chandra image. The projected dark matter fractions within the Einstein radii of A (1''.02) and B (0''.61) are about 0.4 ± 0.3 and 0.55 ± 0.3. The mass to i-band light ratios of A and B, M/L{sub i}∼8±4 M{sub ⊙} L{sub ⊙}{sup −1}, appear comparable to those of radio-quiet lensing galaxies at the same redshift in the CfA-Arizona Space Telescope LEns Survey, Lenses Structure and Dynamics, and Strong Lenses in the Legacy Survey samples. The lensed SMG is extremely bright with observed f(250 μm) = 440 mJy owing to a magnification factor μ ∼ 10. The SMG spectrum shows luminous, narrow C IV λ1549 Å emission, revealing that the SMG houses a hidden quasar in addition to a violent starburst. Multicolor image reconstruction of the SMG indicates a bipolar morphology of the emitted ultraviolet (UV) light suggestive of cones through which UV light escapes a

  10. A sub-millimeter resolution PET detector module using a multi-pixel photon counter array

    International Nuclear Information System (INIS)

    Song, Tae Yong; Wu Heyu; Komarov, Sergey; Tai, Yuan-Chuan; Siegel, Stefan B

    2010-01-01

    A PET block detector module using an array of sub-millimeter lutetium oxyorthosilicate (LSO) crystals read out by an array of surface-mount, semiconductor photosensors has been developed. The detector consists of a LSO array, a custom acrylic light guide, a 3 x 3 multi-pixel photon counter (MPPC) array (S10362-11-050P, Hamamatsu Photonics, Japan) and a readout board with a charge division resistor network. The LSO array consists of 100 crystals, each measuring 0.8 x 0.8 x 3 mm 3 and arranged in 0.86 mm pitches. A Monte Carlo simulation was used to aid the design and fabrication of a custom light guide to control distribution of scintillation light over the surface of the MPPC array. The output signals of the nine MPPC are multiplexed by a charge division resistor network to generate four position-encoded analog outputs. Flood image, energy resolution and timing resolution measurements were performed using standard NIM electronics. The linearity of the detector response was investigated using gamma-ray sources of different energies. The 10 x 10 array of 0.8 mm LSO crystals was clearly resolved in the flood image. The average energy resolution and standard deviation were 20.0% full-width at half-maximum (FWHM) and ±5.0%, respectively, at 511 keV. The timing resolution of a single MPPC coupled to a LSO crystal was found to be 857 ps FWHM, and the value for the central region of detector module was 1182 ps FWHM when ±10% energy window was applied. The nonlinear response of a single MPPC when used to read out a single LSO was observed among the corner crystals of the proposed detector module. However, the central region of the detector module exhibits significantly less nonlinearity (6.5% for 511 keV). These results demonstrate that (1) a charge-sharing resistor network can effectively multiplex MPPC signals and reduce the number of output signals without significantly degrading the performance of a PET detector and (2) a custom light guide to permit light sharing

  11. High spatial resolution brain functional MRI using submillimeter balanced steady-state free precession acquisition

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Pei-Hsin; Chung, Hsiao-Wen [Department of Electrical Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Tsai, Ping-Huei [Imaging Research Center, Taipei Medical University, Taipei 11031, Taiwan and Department of Medical Imaging, Taipei Medical University Hospital, Taipei Medical University, Taipei 11031, Taiwan (China); Wu, Ming-Long, E-mail: minglong.wu@csie.ncku.edu.tw [Institute of Medical Informatics, National Cheng-Kung University, Tainan 70101, Taiwan and Department of Computer Science and Information Engineering, National Cheng-Kung University, Tainan 70101, Taiwan (China); Chuang, Tzu-Chao [Department of Electrical Engineering, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); Shih, Yi-Yu [Siemens Limited Healthcare Sector, Taipei 11503, Taiwan (China); Huang, Teng-Yi [Department of Electrical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China)

    2013-12-15

    Purpose: One of the technical advantages of functional magnetic resonance imaging (fMRI) is its precise localization of changes from neuronal activities. While current practice of fMRI acquisition at voxel size around 3 × 3 × 3 mm{sup 3} achieves satisfactory results in studies of basic brain functions, higher spatial resolution is required in order to resolve finer cortical structures. This study investigated spatial resolution effects on brain fMRI experiments using balanced steady-state free precession (bSSFP) imaging with 0.37 mm{sup 3} voxel volume at 3.0 T. Methods: In fMRI experiments, full and unilateral visual field 5 Hz flashing checkerboard stimulations were given to healthy subjects. The bSSFP imaging experiments were performed at three different frequency offsets to widen the coverage, with functional activations in the primary visual cortex analyzed using the general linear model. Variations of the spatial resolution were achieved by removing outerk-space data components. Results: Results show that a reduction in voxel volume from 3.44 × 3.44 × 2 mm{sup 3} to 0.43 × 0.43 × 2 mm{sup 3} has resulted in an increase of the functional activation signals from (7.7 ± 1.7)% to (20.9 ± 2.0)% at 3.0 T, despite of the threefold SNR decreases in the original images, leading to nearly invariant functional contrast-to-noise ratios (fCNR) even at high spatial resolution. Activation signals aligning nicely with gray matter sulci at high spatial resolution would, on the other hand, have possibly been mistaken as noise at low spatial resolution. Conclusions: It is concluded that the bSSFP sequence is a plausible technique for fMRI investigations at submillimeter voxel widths without compromising fCNR. The reduction of partial volume averaging with nonactivated brain tissues to retain fCNR is uniquely suitable for high spatial resolution applications such as the resolving of columnar organization in the brain.

  12. Gravitation Waves

    CERN Multimedia

    CERN. Geneva

    2005-01-01

    We will present a brief introduction to the physics of gravitational waves and their properties. We will review potential astrophysical sources of gravitational waves, and the physics and astrophysics that can be learned from their study. We will survey the techniques and technologies for detecting gravitational waves for the first time, including bar detectors and broadband interferometers, and give a brief status report on the international search effort, with special emphasis on the LIGO detectors and search results.

  13. Radiation effect of doping and bias conditions on NPN bipolar junction transistors

    International Nuclear Information System (INIS)

    Xi Shanbin; Wang Yiyuan; Xu Fayue; Zhou Dong; Li Ming; Wang Fei; Wang Zhikuan; Yang Yonghui; Lu Wu

    2011-01-01

    In this paper,we investigate 60 Co γ-ray irradiation effects and annealing behaviors of NPN bipolar junction transistors of the same manufacturing technology but different doping concentrations. The transistors of different doping concentrations differ in responses of the radiation effect. More degradation was observed with the transistors of low concentration-doped NPN transistors than the high concentration-doped NPN transistors. The results also demonstrate that reverse-biased transistors are more sensitive to radiation than the forward-biased ones. Mechanisms of the radiation responses are analyzed. (authors)

  14. CMOS front ends for millimeter wave wireless communication systems

    CERN Document Server

    Deferm, Noël

    2015-01-01

    This book focuses on the development of circuit and system design techniques for millimeter wave wireless communication systems above 90GHz and fabricated in nanometer scale CMOS technologies. The authors demonstrate a hands-on methodology that was applied to design six different chips, in order to overcome a variety of design challenges. Behavior of both actives and passives, and how to design them to achieve high performance is discussed in detail. This book serves as a valuable reference for millimeter wave designers, working at both the transistor level and system level.   Discusses advantages and disadvantages of designing wireless mm-wave communication circuits and systems in CMOS; Analyzes the limitations and pitfalls of building mm-wave circuits in CMOS; Includes mm-wave building block and system design techniques and applies these to 6 different CMOS chips; Provides guidelines for building measurement setups to evaluate high-frequency chips.  

  15. LUPUS I observations from the 2010 flight of the Balloon-borne large aperture submillimeter telescope for polarimetry

    International Nuclear Information System (INIS)

    Matthews, Tristan G.; Chapman, Nicholas L.; Novak, Giles; Ade, Peter A. R.; Hargrave, Peter C.; Nutter, David; Angilè, Francesco E.; Devlin, Mark J.; Klein, Jeffrey; Benton, Steven J.; Fissel, Laura M.; Gandilo, Natalie N.; Netterfield, Calvin B.; Chapin, Edward L.; Fukui, Yasuo; Gundersen, Joshua O.; Korotkov, Andrei L.; Moncelsi, Lorenzo; Mroczkowski, Tony K.; Olmi, Luca

    2014-01-01

    The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol) was created by adding polarimetric capability to the BLAST experiment that was flown in 2003, 2005, and 2006. BLASTPol inherited BLAST's 1.8 m primary and its Herschel/SPIRE heritage focal plane that allows simultaneous observation at 250, 350, and 500 μm. We flew BLASTPol in 2010 and again in 2012. Both were long duration Antarctic flights. Here we present polarimetry of the nearby filamentary dark cloud Lupus I obtained during the 2010 flight. Despite limitations imposed by the effects of a damaged optical component, we were able to clearly detect submillimeter polarization on degree scales. We compare the resulting BLASTPol magnetic field map with a similar map made via optical polarimetry. (The optical data were published in 1998 by J. Rizzo and collaborators.) The two maps partially overlap and are reasonably consistent with one another. We compare these magnetic field maps to the orientations of filaments in Lupus I, and we find that the dominant filament in the cloud is approximately perpendicular to the large-scale field, while secondary filaments appear to run parallel to the magnetic fields in their vicinities. This is similar to what is observed in Serpens South via near-IR polarimetry, and consistent with what is seen in MHD simulations by F. Nakamura and Z. Li.

  16. SOFIA MID-INFRARED IMAGING AND CSO SUBMILLIMETER POLARIMETRY OBSERVATIONS OF G034.43+00.24 MM1

    International Nuclear Information System (INIS)

    Jones, T. J.; Gordon, Michael; Shenoy, Dinesh; Gehrz, R. D.; Vaillancourt, John E.; Krejny, M.

    2016-01-01

    We present 11.1 to 37.1 μ m imaging observations of the very dense molecular cloud core MM1 in G034.43+00.24 using FORCAST on SOFIA and submillimeter (submm) polarimetry using SHARP on the Caltech Submillimeter Observatory. We find that at the spatial resolution of SOFIA, the point-spread function (PSF) of MM1 is consistent with being a single source, as expected based on millimeter (mm) and submm observations. The spectral energy distributions (SEDs) of MM1 and MM2 have a warm component at the shorter wavelengths not seen in mm and submm SEDs. Examination of H(1.65 μ m) stellar polarimetry from the Galactic Plane Infrared Polarization Survey shows that G034 is embedded in an external magnetic field aligned with the Galactic Plane. The SHARP polarimetry at 450 μ m shows a magnetic field geometry in the vicinity of MM1 that does not line up with either the Galactic Plane or the mean field direction inferred from the CARMA interferometric polarization map of the central cloud core, but is perpendicular to the long filament in which G034 is embedded. The CARMA polarimetry does show evidence for grain alignment in the central region of the cloud core, and thus does trace the magnetic field geometry near the embedded Class 0 YSO.

  17. LUPUS I observations from the 2010 flight of the Balloon-borne large aperture submillimeter telescope for polarimetry

    Energy Technology Data Exchange (ETDEWEB)

    Matthews, Tristan G.; Chapman, Nicholas L.; Novak, Giles [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Ade, Peter A. R.; Hargrave, Peter C.; Nutter, David [Cardiff University, School of Physics and Astronomy, Queens Buildings, The Parade, Cardiff, CF24 3AA (United Kingdom); Angilè, Francesco E.; Devlin, Mark J.; Klein, Jeffrey [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Benton, Steven J.; Fissel, Laura M.; Gandilo, Natalie N.; Netterfield, Calvin B. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street Toronto, ON M5S 3H4 (Canada); Chapin, Edward L. [XMM SOC, ESAC, Apartado 78, E-28691 Villanueva de la Cañada, Madrid (Spain); Fukui, Yasuo [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan); Gundersen, Joshua O. [Department of Physics, University of Miami, 1320 Campo Sano Drive, Coral Gables, FL 33146 (United States); Korotkov, Andrei L. [Department of Physics, Brown University, 182 Hope Street, Providence, RI 02912 (United States); Moncelsi, Lorenzo; Mroczkowski, Tony K. [California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Olmi, Luca [University of Puerto Rico, Rio Piedras Campus, Physics Department, Box 23343, UPR station, San Juan (Puerto Rico); and others

    2014-04-01

    The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol) was created by adding polarimetric capability to the BLAST experiment that was flown in 2003, 2005, and 2006. BLASTPol inherited BLAST's 1.8 m primary and its Herschel/SPIRE heritage focal plane that allows simultaneous observation at 250, 350, and 500 μm. We flew BLASTPol in 2010 and again in 2012. Both were long duration Antarctic flights. Here we present polarimetry of the nearby filamentary dark cloud Lupus I obtained during the 2010 flight. Despite limitations imposed by the effects of a damaged optical component, we were able to clearly detect submillimeter polarization on degree scales. We compare the resulting BLASTPol magnetic field map with a similar map made via optical polarimetry. (The optical data were published in 1998 by J. Rizzo and collaborators.) The two maps partially overlap and are reasonably consistent with one another. We compare these magnetic field maps to the orientations of filaments in Lupus I, and we find that the dominant filament in the cloud is approximately perpendicular to the large-scale field, while secondary filaments appear to run parallel to the magnetic fields in their vicinities. This is similar to what is observed in Serpens South via near-IR polarimetry, and consistent with what is seen in MHD simulations by F. Nakamura and Z. Li.

  18. Sub-millimeter nuclear medical imaging with high sensitivity in positron emission tomography using β+γ coincidences

    Science.gov (United States)

    Lang, C.; Habs, D.; Parodi, K.; Thirolf, P. G.

    2014-01-01

    We present a nuclear medical imaging technique, employing triple-γ trajectory intersections from β+-γ coincidences, able to reach sub-millimeter spatial resolution in 3 dimensions with a reduced requirement of reconstructed intersections per voxel compared to a conventional PET reconstruction analysis. This 'γ-PET' technique draws on specific β+-decaying isotopes, simultaneously emitting an additional photon. Exploiting the triple coincidence between the positron annihilation and the third photon, it is possible to separate the reconstructed 'true' events from background. In order to characterize this technique, Monte-Carlo simulations and image reconstructions have been performed. The achievable spatial resolution has been found to reach ca. 0.4 mm (FWHM) in each direction for the visualization of a 22Na point source. Only 40 intersections are sufficient for a reliable sub-millimeter image reconstruction of a point source embedded in a scattering volume of water inside a voxel volume of about 1 mm3 ('high-resolution mode'). Moreover, starting with an injected activity of 400 MBq for 76Br, the same number of only about 40 reconstructed intersections are needed in case of a larger voxel volume of 2 x 2 x 3 mm3 ('high-sensitivity mode'). Requiring such a low number of reconstructed events significantly reduces the required acquisition time for image reconstruction (in the above case to about 140 s) and thus may open up the perspective for a quasi real-time imaging.

  19. The Bipolar Field-Effect Transistor: XIII. Physical Realizations of the Transistor and Circuits (One-Two-MOS-Gates on Thin-Thick Pure-Impure Base)

    International Nuclear Information System (INIS)

    Sah, C.-T.; Jie Binbin

    2009-01-01

    This paper reports the physical realization of the Bipolar Field-Effect Transistor (BiFET) and its one-transistor basic building block circuits. Examples are given for the one and two MOS gates on thin and thick, pure and impure base, with electron and hole contacts, and the corresponding theoretical current-voltage characteristics previously computed by us, without generation-recombination-trapping-tunneling of electrons and holes. These examples include the one-MOS-gate on semi-infinite thick impure base transistor (the bulk transistor) and the impurethin-base Silicon-on-Insulator (SOI) transistor and the two-MOS-gates on thin base transistors (the FinFET and the Thin Film Transistor TFT). Figures are given with the cross-section views containing the electron and hole concentration and current density distributions and trajectories and the corresponding DC current-voltage characteristics.

  20. Plasma waves

    National Research Council Canada - National Science Library

    Swanson, D. G

    1989-01-01

    ... Swanson, D.G. (Donald Gary), D a t e - Plasma waves. Bibliography: p. Includes index. 1. Plasma waves. QC718.5.W3S43 1989 ISBN 0-12-678955-X I. Title. 530.4'4 88-34388 Printed in the United Sta...

  1. Wave Dragon

    DEFF Research Database (Denmark)

    Tedd, James; Kofoed, Jens Peter; Friis-Madsen, Erik

    2008-01-01

    Since March 2003 a prototype of Wave Dragon has been tested in an inland sea in Denmark. This has been a great success with all subsystems tested and improved through working in an offshore environment. The project has proved the Wave Dragon device and has enabled the next stage, a production sized...

  2. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Brorsen, Michael; Frigaard, Peter

    Nærværende rapport beskriver numeriske beregninger af den hydrodynamiske interaktion mellem 5 flydere i bølgeenergianlægget Wave Star.......Nærværende rapport beskriver numeriske beregninger af den hydrodynamiske interaktion mellem 5 flydere i bølgeenergianlægget Wave Star....

  3. Outlook and emerging semiconducting materials for ambipolar transistors.

    Science.gov (United States)

    Bisri, Satria Zulkarnaen; Piliego, Claudia; Gao, Jia; Loi, Maria Antonietta

    2014-02-26

    Ambipolar or bipolar transistors are transistors in which both holes and electrons are mobile inside the conducting channel. This device allows switching among several states: the hole-dominated on-state, the off-state, and the electron-dominated on-state. In the past year, it has attracted great interest in exotic semiconductors, such as organic semiconductors, nanostructured materials, and carbon nanotubes. The ability to utilize both holes and electrons inside one device opens new possibilities for the development of more compact complementary metal-oxide semiconductor (CMOS) circuits, and new kinds of optoelectronic device, namely, ambipolar light-emitting transistors. This progress report highlights the recent progresses in the field of ambipolar transistors, both from the fundamental physics and application viewpoints. Attention is devoted to the challenges that should be faced for the realization of ambipolar transistors with different material systems, beginning with the understanding of the importance of interface modification, which heavily affects injections and trapping of both holes and electrons. The recent development of advanced gating applications, including ionic liquid gating, that open up more possibility to realize ambipolar transport in materials in which one type of charge carrier is highly dominant is highlighted. Between the possible applications of ambipolar field-effect transistors, we focus on ambipolar light-emitting transistors. We put this new device in the framework of its prospective for general lightings, embedded displays, current-driven laser, as well as for photonics-electronics interconnection. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Resonant tunneling assisted propagation and amplification of plasmons in high electron mobility transistors

    International Nuclear Information System (INIS)

    Bhardwaj, Shubhendu; Sensale-Rodriguez, Berardi; Xing, Huili Grace; Rajan, Siddharth; Volakis, John L.

    2016-01-01

    A rigorous theoretical and computational model is developed for the plasma-wave propagation in high electron mobility transistor structures with electron injection from a resonant tunneling diode at the gate. We discuss the conditions in which low-loss and sustainable plasmon modes can be supported in such structures. The developed analytical model is used to derive the dispersion relation for these plasmon-modes. A non-linear full-wave-hydrodynamic numerical solver is also developed using a finite difference time domain algorithm. The developed analytical solutions are validated via the numerical solution. We also verify previous observations that were based on a simplified transmission line model. It is shown that at high levels of negative differential conductance, plasmon amplification is indeed possible. The proposed rigorous models can enable accurate design and optimization of practical resonant tunnel diode-based plasma-wave devices for terahertz sources, mixers, and detectors, by allowing a precise representation of their coupling when integrated with other electromagnetic structures

  5. Wavy channel Thin Film Transistor for area efficient, high performance and low power applications

    KAUST Repository

    Hanna, Amir; Sevilla, Galo T.; Ghoneim, Mohamed T.; Hussain, Muhammad Mustafa

    2014-01-01

    We report a new Thin Film Transistor (TFT) architecture that allows expansion of the device width using wavy (continuous without separation) fin features - termed as wavy channel (WC) architecture. This architecture allows expansion of transistor

  6. Multiple-channel detection of cellular activities by ion-sensitive transistors

    Science.gov (United States)

    Machida, Satoru; Shimada, Hideto; Motoyama, Yumi

    2018-04-01

    An ion-sensitive field-effect transistor to record cellular activities was demonstrated. This field-effect transistor (bio transistor) includes cultured cells on the gate insulator instead of gate electrode. The bio transistor converts a change in potential underneath the cells into variation of the drain current when ion channels open. The bio transistor has high detection sensitivity to even minute variations in potential utilizing a subthreshold swing region. To open ion channels, a reagent solution (acetylcholine) was added to a human-originating cell cultured on the bio transistor. The drain current was successfully decreased with the addition of acetylcholine. Moreover, we attempted to detect the opening of ion channels using a multiple-channel measurement circuit containing several bio transistors. As a consequence, the drain current distinctly decreased only after the addition of acetylcholine. We confirmed that this measurement system including bio transistors enables to observation of cellular activities sensitively and simultaneously.

  7. Quantum transport through a deformable molecular transistor

    Science.gov (United States)

    Cornaglia, P. S.; Grempel, D. R.; Ness, H.

    2005-02-01

    The linear transport properties of a model molecular transistor with electron-electron and electron-phonon interactions were investigated analytically and numerically. The model takes into account phonon modulation of the electronic energy levels and of the tunneling barrier between the molecule and the electrodes. When both effects are present they lead to asymmetries in the dependence of the conductance on gate voltage. The Kondo effect is observed in the presence of electron-phonon interactions. There are important qualitative differences between the cases of weak and strong coupling. In the first case the standard Kondo effect driven by spin fluctuations occurs. In the second case, it is driven by charge fluctuations. The Fermi-liquid relation between the spectral density of the molecule and its charge is altered by electron-phonon interactions. Remarkably, the relation between the zero-temperature conductance and the charge remains unchanged. Therefore, there is perfect transmission in all regimes whenever the average number of electrons in the molecule is an odd integer.

  8. Scaling properties of ballistic nano-transistors

    Directory of Open Access Journals (Sweden)

    Wulf Ulrich

    2011-01-01

    Full Text Available Abstract Recently, we have suggested a scale-invariant model for a nano-transistor. In agreement with experiments a close-to-linear thresh-old trace was found in the calculated I D - V D-traces separating the regimes of classically allowed transport and tunneling transport. In this conference contribution, the relevant physical quantities in our model and its range of applicability are discussed in more detail. Extending the temperature range of our studies it is shown that a close-to-linear thresh-old trace results at room temperatures as well. In qualitative agreement with the experiments the I D - V G-traces for small drain voltages show thermally activated transport below the threshold gate voltage. In contrast, at large drain voltages the gate-voltage dependence is weaker. As can be expected in our relatively simple model, the theoretical drain current is larger than the experimental one by a little less than a decade.

  9. Simulation study for the Stratospheric Inferred Wind (SIW) sub-millimeter limb sounder

    Science.gov (United States)

    Baron, Philippe; Murtagh, Donal; Eriksson, Patrick; Ochiai, Satoshi

    2017-04-01

    -and-aac-microtec-to-develop-the-innosat-platform-and-implement-its-first-mission-named-mats.html [2] Wu D., et al.: Mesospheric Doppler wind measurements from Aura Microwave Limb Sounder (MLS), Advanced in Space Research, 42, 1246-1252, 2008 [3] Baron P., et al.: Observation of horizontal winds in the middle-atmosphere between 30S and 55N during the northern winter 2009-2010, Atmospheric Chemistry and Physics 13(13), 6049-6064, 2013, doi:10.5194/acp-13-6049-2013 [4] Baron P., et al.: Definition of an uncooled submillimeter/terahertz limb sounder for measuring middle atmospheric winds, Proceedings of ESA Living Planet Symposium, Edinburgh, UK, 9-13 September 2013, (ESA SP-722, December 2013)

  10. SUB-MILLIMETER TELESCOPE CO (2-1) OBSERVATIONS OF NEARBY STAR-FORMING GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xue-Jian; Gu, Qiusheng [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Wang, Zhong [Harvard-Smithsonian Center for Astrophysics, MS 66, 60 Garden Street, Cambridge, MA 02138 (United States); Wang, Junzhi [Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China); Zhang, Zhi-Yu, E-mail: xjjiang@nju.edu.cn [The UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh, EH9 3HJ (United Kingdom)

    2015-01-20

    We present CO J = 2-1 observations toward 32 nearby gas-rich star-forming galaxies selected from the ALFALFA and Wide-field Infrared Survey Explorer (WISE) catalogs, using the Sub-millimeter Telescope (SMT). Our sample is selected to be dominated by intermediate-M {sub *} galaxies. The scaling relations between molecular gas, atomic gas, and galactic properties (stellar mass, NUV – r, and WISE color W3 – W2) are examined and discussed. Our results show the following. (1) In the galaxies with stellar mass M {sub *} ≤10{sup 10} M {sub ☉}, the H I fraction (f {sub H} {sub I} ≡ M {sub H} {sub I}/M {sub *}) is significantly higher than that of more massive galaxies, while the H{sub 2} gas fraction (f{sub H{sub 2}} ≡ M{sub H{sub 2}}/M {sub *}) remains nearly unchanged. (2) Compared to f{sub H{sub 2}}, f {sub H} {sub I} correlates better with both M {sub *} and NUV – r. (3) A new parameter, WISE color W3 – W2 (12-4.6 μm), is introduced, which is similar to NUV – r in tracing star formation activity, and we find that W3 – W2 has a tighter anti-correlation with log f{sub H{sub 2}} than the anti-correlation of (NUV – r)-f {sub H} {sub I}, (NUV – r)-f{sub H{sub 2}}, and (W3 – W2)-f {sub H} {sub I}. This indicates that W3 – W2 can trace the H{sub 2} fraction in galaxies. For the gas ratio M{sub H{sub 2}}/M {sub H} {sub I} , only in the intermediate-M {sub *} galaxies it appears to depend on M {sub *} and NUV – r. We find a tight correlation between the molecular gas mass M{sub H{sub 2}} and 12 μm (W3) luminosities (L {sub 12} {sub μm}), and the slope is close to unity (1.03 ± 0.06) for the SMT sample. This correlation may reflect that the cold gas and dust are well mixed on a global galactic scale. Using the all-sky 12 μm (W3) data available in WISE, this correlation can be used to estimate CO flux for molecular gas observations and can even predict H{sub 2} mass for star-forming galaxies.

  11. Toward the comprehension of the infrared to submillimeter view of the interstellar medium of nearby galaxies

    International Nuclear Information System (INIS)

    Galametz, Maud

    2010-01-01

    This thesis aims to study the interstellar medium (ISM) of nearby galaxies to characterize the physical properties of the gas and dust. We especially focused our study on low-metallicity galaxies of the Local Universe, ideal candidates to study the influence of metal enrichment on the ISM properties of galaxies. Previous studies have shown that the Spectral Energy Distributions (SEDs) of low metallicity galaxies differ significantly from those of massive galaxies and that the dust-to-gas mass ratio (D/G) of the galaxy could be dependent of the metallicity. Observations of low-metallicity galaxies also often led to the detection of an excess at submillimeter (sub-mm) wavelengths not always accounted for in usual SED models. Further studies and observations had to be performed to better cover the far-IR to sub-mm range and probe the coldest phase of dust. We adopt a multi-wavelength approach to model and analyse the SEDs of 4 low-metallicity galaxies observed with LABOCA at 870 μm. We estimated the fraction of cool dust to be significant compared to the total dust mass of the galaxies. Some D/Gs are incoherent compared to what is expected from the current chemical evolution model, revealing possible reservoirs of gas not detected by current HI or CO observations. I enlarged the first sample to a wider range of metallicities and showed that sub-mm measurements significantly affect the dust mass estimates of galaxies. For dustier galaxies for which the SED usually peaks at longer wavelengths, sub-mm fluxes are crucial to position the peak and the Rayleigh-Jeans slope of their SED. For low-metallicity galaxies, the sub-mm wavelength domain harbours an excess that may imply a large amount of very cold dust. Our results confirm that low-metallicity galaxies can exhibit a sub-mm excess when observed at longer wavelengths. Obtaining a more precise inventory of the cold dust and resolve the main actors of dust evolution in massive star forming regions and molecular clouds

  12. Quasitravelling waves

    International Nuclear Information System (INIS)

    Beklaryan, Leva A

    2011-01-01

    A finite difference analogue of the wave equation with potential perturbation is investigated, which simulates the behaviour of an infinite rod under the action of an external longitudinal force field. For a homogeneous rod, describing solutions of travelling wave type is equivalent to describing the full space of classical solutions to an induced one-parameter family of functional differential equations of point type, with the characteristic of the travelling wave as parameter. For an inhomogeneous rod, the space of solutions of travelling wave type is trivial, and their 'proper' extension is defined as solutions of 'quasitravelling' wave type. By contrast to the case of a homogeneous rod, describing the solutions of quasitravelling wave type is equivalent to describing the quotient of the full space of impulsive solutions to an induced one-parameter family of point-type functional differential equations by an equivalence relation connected with the definition of solutions of quasitravelling wave type. Stability of stationary solutions is analyzed. Bibliography: 9 titles.

  13. Transistor reset preamplifier for high-rate high-resolution spectroscopy

    International Nuclear Information System (INIS)

    Landis, D.A.; Cork, C.P.; Madden, N.W.; Goulding, F.S.

    1981-10-01

    Pulsed transistor reset of high resolution charge sensitive preamplifiers used in cooled semiconductor spectrometers can sometimes have an advantage over pulsed light reset systems. Several versions of transistor reset spectrometers using both silicon and germanium detectors have been built. This paper discusses the advantages of the transistor reset system and illustrates several configurations of the packages used for the FET and reset transistor. It also describes the preamplifer circuit and shows the performance of the spectrometer at high rates

  14. Evolution of the MOS transistor - From conception to VLSI

    International Nuclear Information System (INIS)

    Sah, C.T.

    1988-01-01

    Historical developments of the metal-oxide-semiconductor field-effect-transistor (MOSFET) during the last sixty years are reviewed, from the 1928 patent disclosures of the field-effect conductivity modulation concept and the semiconductor triodes structures proposed by Lilienfeld to the 1947 Shockley-originated efforts which led to the laboratory demonstration of the modern silicon MOSFET thirty years later in 1960. A survey is then made of the milestones of the past thirty years leading to the latest submicron silicon logic CMOS (Complementary MOS) and BICMOS (Bipolar-Junction-Transistor CMOS combined) arrays and the three-dimensional and ferroelectric extensions of Dennard's one-transistor dynamic random access memory (DRAM) cell. Status of the submicron lithographic technologies (deep ultra-violet light, X-ray, electron-beam) are summarized. Future trends of memory cell density and logic gate speed are projected. Comparisons of the switching speed of the silicon MOSFET with that of silicon bipolar and GaAs field-effect transistors are reviewed. Use of high-temperature superconducting wires and GaAs-on-Si monolithic semiconductor optical clocks to break the interconnect-wiring delay barrier is discussed. Further needs in basic research and mathematical modeling on the failure mechanisms in submicron silicon transistors at high electric fields (hot electron effects) and in interconnection conductors at high current densities and low as well as high electric fields (electromigration) are indicated

  15. Self-Consistent Study of Conjugated Aromatic Molecular Transistors

    International Nuclear Information System (INIS)

    Jing, Wang; Yun-Ye, Liang; Hao, Chen; Peng, Wang; Note, R.; Mizuseki, H.; Kawazoe, Y.

    2010-01-01

    We study the current through conjugated aromatic molecular transistors modulated by a transverse field. The self-consistent calculation is realized with density function theory through the standard quantum chemistry software Gaussian03 and the non-equilibrium Green's function formalism. The calculated I – V curves controlled by the transverse field present the characteristics of different organic molecular transistors, the transverse field effect of which is improved by the substitutions of nitrogen atoms or fluorine atoms. On the other hand, the asymmetry of molecular configurations to the axis connecting two sulfur atoms is in favor of realizing the transverse field modulation. Suitably designed conjugated aromatic molecular transistors possess different I – V characteristics, some of them are similar to those of metal-oxide-semiconductor field-effect transistors (MOSFET). Some of the calculated molecular devices may work as elements in graphene electronics. Our results present the richness and flexibility of molecular transistors, which describe the colorful prospect of next generation devices. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  16. Electromechanical field effect transistors based on multilayer phosphorene nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Z.T., E-mail: jiangzhaotan@hotmail.com; Lv, Z.T.; Zhang, X.D.

    2017-06-21

    Based on the tight-binding Hamiltonian approach, we demonstrate that the electromechanical field effect transistors (FETs) can be realized by using the multilayer phosphorene nanoribbons (PNRs). The synergistic combination of the electric field and the external strains can establish the on–off switching since the electric field can shift or split the energy band, and the mechanical strains can widen or narrow the band widths. This kind of multilayer PNR FETs, much solider than the monolayer PNR one and more easily biased by different electric fields, has more transport channels consequently leading to the higher on–off current ratio or the higher sensitivity to the electric fields. Meanwhile, the strain-induced band-flattening will be beneficial for improving the flexibility in designing the electromechanical FETs. In addition, such electromechanical FETs can act as strain-controlled FETs or mechanical detectors for detecting the strains, indicating their potential applications in nano- and micro-electromechanical fields. - Highlights: • Electromechanical transistors are designed with multilayer phosphorene nanoribbons. • Electromechanical synergistic effect can establish the on–off switching more flexibly. • Multilayer transistors, solider and more easily biased, has more transport channels. • Electromechanical transistors can act as strain-controlled transistors or mechanical detectors.

  17. Inexpensive Measuring System for the Characterization of Organic Transistors

    Directory of Open Access Journals (Sweden)

    Clara Pérez-Fuster

    2018-01-01

    Full Text Available A measuring module has been specifically designed for the electrical characterization of organic semiconductor devices such as organic field effect transistors (OFETs and organic electrochemical transistors (OECTs according to the IEEE 1620-2008 standard. This device has been tested with OFETs based on 6,13-bis(triisopropylsilylethinylpentacene (TIPS-pentacene. The measuring system has been constructed using a NI-PXIe-1073 chassis with integrated controller and two NI-PXI-4132 programmable high-precision source measure units (SMUs that offer a four-quadrant ± 100 V output, with resolution down to 10 pA. LabVIEW™ has been used to develop the appropriate program. Most of the main OFET parameters included in the IEEE 1620 standard can be measured by means of this device. Although nowadays expensive devices for the characterization of Si-based transistors are available, devices for the characterization of organic transistors are not yet widespread in the market. Fabrication of a specific and flexible module that can be used to characterize this type of transistors would provide a powerful tool to researchers.

  18. ALMA OBSERVATIONS OF THE SUBMILLIMETER DENSE MOLECULAR GAS TRACERS IN THE LUMINOUS TYPE-1 ACTIVE NUCLEUS OF NGC 7469

    International Nuclear Information System (INIS)

    Izumi, Takuma; Kohno, Kotaro; Ikarashi, Soh; Aalto, Susanne; Doi, Akihiro; Espada, Daniel; Fathi, Kambiz; Harada, Nanase; Hsieh, Pei-Ying; Matsushita, Satoki; Hatsukade, Bunyo; Hattori, Takashi; Imanishi, Masatoshi; Iono, Daisuke; Ishizuki, Sumio; Nagai, Hiroshi; Krips, Melanie; Martín, Sergio; Meier, David S.; Nakai, Naomasa

    2015-01-01

    We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 1 observations of the central kiloparsec region of the luminous type 1 Seyfert galaxy NGC 7469 with unprecedented high resolution (0.″5 ×0.″4 = 165 × 132 pc) at submillimeter wavelengths. Utilizing the wide bandwidth of ALMA, we simultaneously obtained HCN(4–3), HCO + (4–3), CS(7–6), and partially CO(3–2) line maps, as well as the 860 μm continuum. The region consists of the central ∼1″ component and the surrounding starburst ring with a radius of ∼1.″5–2.″5. Several structures connect these components. Except for CO(3–2), these dense gas tracers are significantly concentrated toward the central ∼1″, suggesting their suitability to probe the nuclear regions of galaxies. Their spatial distribution resembles well those of centimeter and mid-infrared continuum emissions, but it is anticorrelated with the optical one, indicating the existence of dust-obscured star formation. The integrated intensity ratios of HCN(4–3)/HCO + (4–3) and HCN(4–3)/CS(7–6) are higher at the active galactic nucleus (AGN) position than at the starburst ring, which is consistent with our previous findings (submillimeter-HCN enhancement). However, the HCN(4–3)/HCO + (4–3) ratio at the AGN position of NGC 7469 (1.11 ± 0.06) is almost half of the corresponding value of the low-luminosity type 1 Seyfert galaxy NGC 1097 (2.0 ± 0.2), despite the more than two orders of magnitude higher X-ray luminosity of NGC 7469. But the ratio is comparable to that of the close vicinity of the AGN of NGC 1068 (∼1.5). Based on these results, we speculate that some heating mechanisms other than X-ray (e.g., mechanical heating due to an AGN jet) can contribute significantly for shaping the chemical composition in NGC 1097

  19. THE SCUBA-2 COSMOLOGY LEGACY SURVEY: MULTIWAVELENGTH COUNTERPARTS TO 10{sup 3} SUBMILLIMETER GALAXIES IN THE UKIDSS-UDS FIELD

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chian-Chou; Smail, Ian; Ma, Cheng-Jiun; Simpson, James M.; Swinbank, A. Mark [Centre for Extragalactic Astronomy, Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Ivison, Rob J.; Arumugam, Vinodiran; Mortlock, Alice; Dunlop, James S.; Michałowski, Michał J. [Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Almaini, Omar; Conselice, Christopher J.; Hartley, Will G. [University of Nottingham, School of Physics and Astronomy, Nottingham, NG7 2RD (United Kingdom); Geach, James E. [Center for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Simpson, Chris [Astrophysics Research Institute, Liverpool John Moores University, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF (United Kingdom); Aretxaga, Itziar [Instituto Nacional de Astrofísica, Óptica y Electrónica (INAOE), Luis Enrique Erro 1, Sta. Ma. Tonantzintla, Puebla (Mexico); Blain, Andrew [Physics and Astronomy, University of Leicester, Leicester, LE1 7RH (United Kingdom); Chapman, Scott C. [Department of Physics and Atmospheric Science, Dalhousie University, 6310 Coburg Road, Halifax, NS B3H 4R2 (Canada); Farrah, Duncan [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Halpern, Mark [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); and others

    2016-04-01

    We present multiwavelength identifications for the counterparts of 1088 submillimeter sources detected at 850 μm in the SCUBA-2 Cosmology Legacy Survey study of the UKIRT Infrared Deep Sky Survey-Ultra-Deep Survey (UDS) field. By utilizing an Atacama Large Millimeter Array (ALMA) pilot study on a subset of our bright SCUBA-2 sample as a training set, along with the deep optical–near-infrared (OIR) data available in this field, we develop a novel technique, Optical–IR Triple Color (OIRTC), using z − K, K − [3.6], [3.6] − [4.5] colors to select the candidate submillimeter galaxy (SMG) counterparts. By combining radio identification and the OIRTC technique, we find counterpart candidates for 80% of the Class = 1 ≥ 4σ SCUBA-2 sample, defined as those that are covered by both radio and OIR imaging and the base sample for our scientific analyses. Based on the ALMA training set, we expect the accuracy of these identifications to be 82% ± 20%, with a completeness of 69% ± 16%, essentially as accurate as the traditional p-value technique but with higher completeness. We find that the fraction of SCUBA-2 sources having candidate counterparts is lower for fainter 850 μm sources, and we argue that for follow-up observations sensitive to SMGs with S{sub 850} ≳ 1 mJy across the whole ALMA beam, the fraction with multiple counterparts is likely to be >40% for SCUBA-2 sources at S{sub 850} ≳ 4 mJy. We find that the photometric redshift distribution for the SMGs is well fit by a lognormal distribution, with a median redshift of z = 2.3 ± 0.1. After accounting for the sources without any radio and/or OIRTC counterpart, we estimate the median redshift to be z = 2.6 ± 0.1 for SMGs with S{sub 850} > 1 mJy. We also use this new large sample to study the clustering of SMGs and the far-infrared properties of the unidentified submillimeter sources by stacking their Herschel SPIRE far-infrared emission.

  20. ALMA OBSERVATIONS OF THE SUBMILLIMETER DENSE MOLECULAR GAS TRACERS IN THE LUMINOUS TYPE-1 ACTIVE NUCLEUS OF NGC 7469

    Energy Technology Data Exchange (ETDEWEB)

    Izumi, Takuma; Kohno, Kotaro; Ikarashi, Soh [Institute of Astronomy, School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Aalto, Susanne [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Observatory, SE-439 94 Onsala (Sweden); Doi, Akihiro [Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara 252-5210 (Japan); Espada, Daniel [Joint ALMA Observatory, Alonso de Córdova, 3107, Vitacura, Santiago 763-0355 (Chile); Fathi, Kambiz [Stockholm Observatory, Department of Astronomy, Stockholm University, AlbaNova Centre, SE-106 91 Stockholm (Sweden); Harada, Nanase; Hsieh, Pei-Ying; Matsushita, Satoki [Academia Sinica, Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China); Hatsukade, Bunyo; Hattori, Takashi; Imanishi, Masatoshi; Iono, Daisuke; Ishizuki, Sumio; Nagai, Hiroshi [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Krips, Melanie; Martín, Sergio [Institut de Radio Astronomie Millimétrique, 300 rue de la Piscine, Domaine Universitaire, F-38406 St. Martin d’Hères (France); Meier, David S. [Department of Physics, New Mexico Institute of Mining and Technology, 801 Leroy Place, Soccoro, NM 87801 (United States); Nakai, Naomasa, E-mail: takumaizumi@ioa.s.u-tokyo.ac.jp [Department of Physics, Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Ten-nodai, Tsukuba, Ibaraki 305-8571 (Japan); and others

    2015-09-20

    We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 1 observations of the central kiloparsec region of the luminous type 1 Seyfert galaxy NGC 7469 with unprecedented high resolution (0.″5 ×0.″4 = 165 × 132 pc) at submillimeter wavelengths. Utilizing the wide bandwidth of ALMA, we simultaneously obtained HCN(4–3), HCO{sup +}(4–3), CS(7–6), and partially CO(3–2) line maps, as well as the 860 μm continuum. The region consists of the central ∼1″ component and the surrounding starburst ring with a radius of ∼1.″5–2.″5. Several structures connect these components. Except for CO(3–2), these dense gas tracers are significantly concentrated toward the central ∼1″, suggesting their suitability to probe the nuclear regions of galaxies. Their spatial distribution resembles well those of centimeter and mid-infrared continuum emissions, but it is anticorrelated with the optical one, indicating the existence of dust-obscured star formation. The integrated intensity ratios of HCN(4–3)/HCO{sup +}(4–3) and HCN(4–3)/CS(7–6) are higher at the active galactic nucleus (AGN) position than at the starburst ring, which is consistent with our previous findings (submillimeter-HCN enhancement). However, the HCN(4–3)/HCO{sup +}(4–3) ratio at the AGN position of NGC 7469 (1.11 ± 0.06) is almost half of the corresponding value of the low-luminosity type 1 Seyfert galaxy NGC 1097 (2.0 ± 0.2), despite the more than two orders of magnitude higher X-ray luminosity of NGC 7469. But the ratio is comparable to that of the close vicinity of the AGN of NGC 1068 (∼1.5). Based on these results, we speculate that some heating mechanisms other than X-ray (e.g., mechanical heating due to an AGN jet) can contribute significantly for shaping the chemical composition in NGC 1097.

  1. Submillimeter H2O and H2O+emission in lensed ultra- and hyper-luminous infrared galaxies at z 2-4

    NARCIS (Netherlands)

    Yang, C.; Omont, A.; Beelen, A.; González-Alfonso, E.; Neri, R.; Gao, Y.; van der Werf, P.; Weiß, A.; Gavazzi, R.; Falstad, N.; Baker, A. J.; Bussmann, R. S.; Cooray, A.; Cox, P.; Dannerbauer, H.; Dye, S.; Guélin, M.; Ivison, R.; Krips, M.; Lehnert, M.; Michałowski, M. J.; Riechers, D. A.; Spaans, M.; Valiante, E.

    2016-01-01

    We report rest-frame submillimeter H2O emission line observations of 11 ultra- or hyper-luminous infrared galaxies (ULIRGs or HyLIRGs) at z 2-4 selected among the brightest lensed galaxies discovered in the Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS). Using the IRAM NOrthern

  2. Deep Submillimeter and Radio Observations in the SSA22 Field. I. Powering Sources and the Lyα Escape Fraction of Lyα Blobs

    Science.gov (United States)

    Ao, Y.; Matsuda, Y.; Henkel, C.; Iono, D.; Alexander, D. M.; Chapman, S. C.; Geach, J.; Hatsukade, B.; Hayes, M.; Hine, N. K.; Kato, Y.; Kawabe, R.; Kohno, K.; Kubo, M.; Lehnert, M.; Malkan, M.; Menten, K. M.; Nagao, T.; Norris, R. P.; Ouchi, M.; Saito, T.; Tamura, Y.; Taniguchi, Y.; Umehata, H.; Weiss, A.

    2017-12-01

    We study the heating mechanisms and Lyα escape fractions of 35 Lyα blobs (LABs) at z ≈ 3.1 in the SSA22 field. Dust continuum sources have been identified in 11 of the 35 LABs, all with star formation rates (SFRs) above 100 M ⊙ yr-1. Likely radio counterparts are detected in 9 out of 29 investigated LABs. The detection of submillimeter dust emission is more linked to the physical size of the Lyα emission than to the Lyα luminosities of the LABs. A radio excess in the submillimeter/radio-detected LABs is common, hinting at the presence of active galactic nuclei. Most radio sources without X-ray counterparts are located at the centers of the LABs. However, all X-ray counterparts avoid the central regions. This may be explained by absorption due to exceptionally large column densities along the line-of-sight or by LAB morphologies, which are highly orientation dependent. The median Lyα escape fraction is about 3% among the submillimeter-detected LABs, which is lower than a lower limit of 11% for the submillimeter-undetected LABs. We suspect that the large difference is due to the high dust attenuation supported by the large SFRs, the dense large-scale environment as well as large uncertainties in the extinction corrections required to apply when interpreting optical data.

  3. The effect and mechanism of the bipolar junction transistor in different temperature

    International Nuclear Information System (INIS)

    Wang Dong; Lu Wu; Ren Diyuan; Li Aiwu; Kuang Zhibing

    2007-01-01

    The annealing-effect of bipolar junction transistor in different temperature is investigated. It is found that the anneal of the bipolar transistor is related to the annealing-temperature, and the annealing-effect of the different type transistor is dissimilar. The possible mechanism is discussed. (authors)

  4. Investigation of Impact of the Gate Circuitry on IGBT Transistor Dynamic Parameters

    Directory of Open Access Journals (Sweden)

    Vytautas Bleizgys

    2011-03-01

    Full Text Available The impact of Insulated Gate Bipolar Transistor driver circuit parameters on the rise and fall time of the collector current and voltage collector-emitter was investigated. The influence of transistor driver circuit parameters on heating of Insulated Gate Bipolar Transistors was investigated as well.Article in Lithuanian

  5. Ambipolar organic tri-gate transistor for low-power complementary electronics

    NARCIS (Netherlands)

    Torricelli, F.; Ghittorelli, M.; Smits, E.C.P.; Roelofs, C.; Janssen, R.A.J.; Gelinck, G.H.; Kovács-Vajna, Z.M.; Cantatore, E.

    2016-01-01

    Ambipolar transistors typically suffer from large off-current inherently due to ambipolar conduction. Using a tri-gate transistor it is shown that it is possible to electrostatically switch ambipolar polymer transistors from ambipolar to unipolar mode. In unipolar mode, symmetric characteristics

  6. Tetracene-based organic light-emitting transistors: optoelectronic properties and electron injection mechanism

    NARCIS (Netherlands)

    Santato, C.; Capelli, R.; Loi, M.A.; Murgia, M.; Cicoira, F.; Roy, Arunesh; Stallinga, P; Zamboni, R.; Rost, C.; Karg, S.F.; Muccini, M.

    2004-01-01

    Optoelectronic properties of light-emitting field-effect transistors (LETs) fabricated on bottom-contact transistor structures using a tetracene film as charge-transport and light-emitting material are investigated. Electroluminescence generation and transistor current are correlated, and the bias

  7. Development and Experimental Evaluation of an Automated Multi-Media Course on Transistors.

    Science.gov (United States)

    Whitted, J.H., Jr.; And Others

    A completely automated multi-media self-study program for teaching a portion of electronic solid-state fundamentals was developed. The subject matter areas included were fundamental theory of transistors, transistor amplifier fundamentals, and simple mathematical analysis of transistors including equivalent circuits, parameters, and characteristic…

  8. Nanowire transistors physics of devices and materials in one dimension

    CERN Document Server

    Colinge, Jean-Pierre

    2016-01-01

    From quantum mechanical concepts to practical circuit applications, this book presents a self-contained and up-to-date account of the physics and technology of nanowire semiconductor devices. It includes a unified account of the critical ideas central to low-dimensional physics and transistor physics which equips readers with a common framework and language to accelerate scientific and technological developments across the two fields. Detailed descriptions of novel quantum mechanical effects such as quantum current oscillations, the metal-to-semiconductor transition and the transition from classical transistor to single-electron transistor operation are described in detail, in addition to real-world applications in the fields of nanoelectronics, biomedical sensing techniques, and advanced semiconductor research. Including numerous illustrations to help readers understand these phenomena, this is an essential resource for researchers and professional engineers working on semiconductor devices and materials in ...

  9. Combinatorial study of zinc tin oxide thin-film transistors

    Science.gov (United States)

    McDowell, M. G.; Sanderson, R. J.; Hill, I. G.

    2008-01-01

    Groups of thin-film transistors using a zinc tin oxide semiconductor layer have been fabricated via a combinatorial rf sputtering technique. The ZnO :SnO2 ratio of the film varies as a function of position on the sample, from pure ZnO to SnO2, allowing for a study of zinc tin oxide transistor performance as a function of channel stoichiometry. The devices were found to have mobilities ranging from 2to12cm2/Vs, with two peaks in mobility in devices at ZnO fractions of 0.80±0.03 and 0.25±0.05, and on/off ratios as high as 107. Transistors composed predominantly of SnO2 were found to exhibit light sensitivity which affected both the on/off ratios and threshold voltages of these devices.

  10. Fully printed metabolite sensor using organic electrochemical transistor

    Science.gov (United States)

    Scheiblin, Gaëtan; Aliane, Abdelkader; Coppard, Romain; Owens, Róisín. M.; Mailley, Pascal; Malliaras, George G.

    2015-08-01

    As conducting polymer based devices, organic electrochemical transistors (OECTs) are suited for printing process. The convenience of the screen-printing techniques allowed us to design and fabricate OECTs with a selected design and using different gate material. Depending on the material used, we were able to tune the transistor for different biological application. Ag/AgCl gate provided transistor with good transconductance, and electrochemical sensitivity to pH was provided by polyaniline ink. Finally, we validate the enzymatic sensing of glucose and lactate with a Poly(3,4-ethylene dioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS) gate often used due to its biocompatible properties. The screen-printing process allowed us to fabricate a large amount of devices in a short period of time, using only commercially available grades of ink, showing by this way the possible transfer to industrial purpose.

  11. Quantum engineering of transistors based on 2D materials heterostructures

    Science.gov (United States)

    Iannaccone, Giuseppe; Bonaccorso, Francesco; Colombo, Luigi; Fiori, Gianluca

    2018-03-01

    Quantum engineering entails atom-by-atom design and fabrication of electronic devices. This innovative technology that unifies materials science and device engineering has been fostered by the recent progress in the fabrication of vertical and lateral heterostructures of two-dimensional materials and by the assessment of the technology potential via computational nanotechnology. But how close are we to the possibility of the practical realization of next-generation atomically thin transistors? In this Perspective, we analyse the outlook and the challenges of quantum-engineered transistors using heterostructures of two-dimensional materials against the benchmark of silicon technology and its foreseeable evolution in terms of potential performance and manufacturability. Transistors based on lateral heterostructures emerge as the most promising option from a performance point of view, even if heterostructure formation and control are in the initial technology development stage.

  12. Planar transistors and impatt diodes with ion implantation

    International Nuclear Information System (INIS)

    Dorendorf, H.; Glawischnig, H.; Grasser, L.; Hammerschmitt, J.

    1975-03-01

    Low frequency planar npn and pnp transistors have been developed in which the base and emitter have been fabricated using ion implantation of boron and phosphorus by a drive-in diffusion. Electrical parameters of the transistors are comparable with conventionally produced transistors; the noise figure was improved and production tolerances were significantly reduced. Silicon-impatt diodes for the microwave range were also fabricated with implanted pn junctions and tested for their high frequency characteristics. These diodes, made in an improved upside down technology, delivered output power up to 40 mW (burn out power) at 30 GHz. Reverse leakage current and current carrying capability of these diodes were comparable to diffused structures. (orig.) 891 ORU 892 MB [de

  13. Effects on focused ion beam irradiation on MOS transistors

    International Nuclear Information System (INIS)

    Campbell, A.N.; Peterson, K.A.; Fleetwood, D.M.; Soden, J.M.

    1997-01-01

    The effects of irradiation from a focused ion beam (FIB) system on MOS transistors are reported systematically for the first time. Three MOS transistor technologies, with 0.5, 1, and 3 μm minimum feature sizes and with gate oxide thicknesses ranging from 11 to 50 nm, were analyzed. Significant shifts in transistor parameters (such as threshold voltage, transconductance, and mobility) were observed following irradiation with a 30 keV Ga + focused ion beam with ion doses varying by over 5 orders of magnitude. The apparent damage mechanism (which involved the creation of interface traps, oxide trapped charge, or both) and extent of damage were different for each of the three technologies investigated

  14. Fermilab main accelerator quadrupole transistorized regulators for improved tune stability

    International Nuclear Information System (INIS)

    Yarema, R.J.; Pfeffer, H.

    1977-01-01

    During early operation of the Fermilab Main Accelerator, tune fluctuations, caused by the SCR-controlled power supplies in the quad bus, limited the beam aperature at low energies. To correct this problem, two transistorized power supplies were built in 1975 to regulate and filter the main ring quad magnet current during injection and beam acceleration through the rf transistion region. There is one power supply in series with each quad bus. Each supply uses 320 parallel power transistors and is rated at 300A, 120V. Since the voltage and current capabilities of the transistorized supplies are limited, the supplies are turned-off at about 25GeV. A real-time computer system initiates turn-on of the SCR-controlled power supplies and regulation takeover by the SCR-controlled supplies, at the appropriate times

  15. Transport Mechanisms in Organic Thin-Film Transistors

    Science.gov (United States)

    Fung, A. W. P.

    1996-03-01

    Recent success in fabricating field-effect transistors with polycrystalline α-sexithiophene (α-6T) has allowed us to study charge transport in this organic semiconductor. The appealing structural property that the oligomer chains are seated almost perpendicular to the substrate provides a model π-conjugated system which we find exhibits band transport at low temperatures. We observe a behavioral transition around 50K which is consistent with the metal-insulator transition in Holstein's small-polaron theory. The fact that we can observe intrinsic behavior means that the ambient-temperature mobility obtained in these transistors is optimal for α-6T. Agreement with the Holstein theory provides us with a prescription for rational design of materials for organic transistor applications. Work done in collaboration with L. Torsi, A. Dodabalapur, L. J. Rothberg and H. E. Katz.

  16. A Klein-tunneling transistor with ballistic graphene

    International Nuclear Information System (INIS)

    Wilmart, Quentin; Fève, Gwendal; Berroir, Jean-Marc; Plaçais, Bernard; Berrada, Salim; Hung Nguyen, V; Dollfus, Philippe; Torrin, David

    2014-01-01

    Today, the availability of high mobility graphene up to room temperature makes ballistic transport in nanodevices achievable. In particular, p-n-p transistors in the ballistic regime give access to Klein tunneling physics and allow the realization of devices exploiting the optics-like behavior of Dirac Fermions (DFs) as in the Veselago lens or the Fabry–Pérot cavity. Here we propose a Klein tunneling transistor based on the geometrical optics of DFs. We consider the case of a prismatic active region delimited by a triangular gate, where total internal reflection may occur, which leads to the tunable suppression of transistor transmission. We calculate the transmission and the current by means of scattering theory and the finite bias properties using non-equilibrium Green's function (NEGF) simulation. (letter)

  17. A Klein-tunneling transistor with ballistic graphene

    Energy Technology Data Exchange (ETDEWEB)

    Wilmart, Quentin; Fève, Gwendal; Berroir, Jean-Marc; Plaçais, Bernard [Laboratoire Pierre Aigrain, Ecole Normale Supérieure, CNRS (UMR 8551), Université P et M Curie, Université D Diderot, 24, rue Lhomond, 75231 Paris Cedex 05 (France); Berrada, Salim; Hung Nguyen, V; Dollfus, Philippe [Institute of Fundamental Electronics, Univ. Paris-Sud, CNRS, Orsay (France); Torrin, David [Département de Physique, Ecole Polytechnique, 91128 Palaiseau (France)

    2014-06-15

    Today, the availability of high mobility graphene up to room temperature makes ballistic transport in nanodevices achievable. In particular, p-n-p transistors in the ballistic regime give access to Klein tunneling physics and allow the realization of devices exploiting the optics-like behavior of Dirac Fermions (DFs) as in the Veselago lens or the Fabry–Pérot cavity. Here we propose a Klein tunneling transistor based on the geometrical optics of DFs. We consider the case of a prismatic active region delimited by a triangular gate, where total internal reflection may occur, which leads to the tunable suppression of transistor transmission. We calculate the transmission and the current by means of scattering theory and the finite bias properties using non-equilibrium Green's function (NEGF) simulation. (letter)

  18. Quantum engineering of transistors based on 2D materials heterostructures.

    Science.gov (United States)

    Iannaccone, Giuseppe; Bonaccorso, Francesco; Colombo, Luigi; Fiori, Gianluca

    2018-03-01

    Quantum engineering entails atom-by-atom design and fabrication of electronic devices. This innovative technology that unifies materials science and device engineering has been fostered by the recent progress in the fabrication of vertical and lateral heterostructures of two-dimensional materials and by the assessment of the technology potential via computational nanotechnology. But how close are we to the possibility of the practical realization of next-generation atomically thin transistors? In this Perspective, we analyse the outlook and the challenges of quantum-engineered transistors using heterostructures of two-dimensional materials against the benchmark of silicon technology and its foreseeable evolution in terms of potential performance and manufacturability. Transistors based on lateral heterostructures emerge as the most promising option from a performance point of view, even if heterostructure formation and control are in the initial technology development stage.

  19. Carbon Nanotube Thin Film Transistors for Flat Panel Display Application.

    Science.gov (United States)

    Liang, Xuelei; Xia, Jiye; Dong, Guodong; Tian, Boyuan; Peng, Lianmao

    2016-12-01

    Carbon nanotubes (CNTs) are promising materials for both high performance transistors for high speed computing and thin film transistors for macroelectronics, which can provide more functions at low cost. Among macroelectronics applications, carbon nanotube thin film transistors (CNT-TFT) are expected to be used soon for backplanes in flat panel displays (FPDs) due to their superior performance. In this paper, we review the challenges of CNT-TFT technology for FPD applications. The device performance of state-of-the-art CNT-TFTs are compared with the requirements of TFTs for FPDs. Compatibility of the fabrication processes of CNT-TFTs and current TFT technologies are critically examined. Though CNT-TFT technology is not yet ready for backplane production line of FPDs, the challenges can be overcome by close collaboration between research institutes and FPD manufacturers in the short term.

  20. High Stability Pentacene Transistors Using Polymeric Dielectric Surface Modifier.

    Science.gov (United States)

    Wang, Xiaohong; Lin, Guangqing; Li, Peng; Lv, Guoqiang; Qiu, Longzhen; Ding, Yunsheng

    2015-08-01

    1,6-bis(trichlorosilyl)hexane (C6Cl), polystyrene (PS), and cross-linked polystyrene (CPS) were investigated as gate dielectric modified layers for high performance organic transistors. The influence of the surface energy, roughness and morphology on the charge transport of the organic thin-film transistors (OTFTs) was investigated. The surface energy and roughness both affect the grain size of the pentacene films which will control the charge carrier mobility of the devices. Pentacene thin-film transistors fabricated on the CPS modified dielectric layers exhibited charge carrier mobility as high as 1.11 cm2 V-1 s-1. The bias stress stability for the CPS devices shows that the drain current only decays 1% after 1530 s and the mobility never decreases until 13530 s.