Bulletin of the American Physical Society
APS March Meeting 2015
Volume 60, Number 1
Monday–Friday, March 2–6, 2015; San Antonio, Texas
Session B21: Detectors, Sensors, & Transducers |
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Sponsoring Units: GIMS Chair: Charles Mielke, Los Alamos National Laboratory Room: 201 |
Monday, March 2, 2015 11:15AM - 11:27AM |
B21.00001: Neutron detection using far ultraviolet radiation from noble-gas excimers Michael A. Coplan, Jacob C. McComb, Mohamad I. Al-Sheikhly, Eric Miller, Christopher M. Lavelle, Alan K. Thompson, Robert E. Vest, Charles W. Clark When triggered in a noble gas medium at around atmospheric pressure, low-energy neutron-absorption reactions such as $^3$He(n,tp) \footnote{P. P. Hughes, {\em et al., Appl. Phys. Lett.} {\bf 97}, 234105 (2010)} and $^{10}$B(n,$\alpha$)$^7$Li \footnote{J. C. McComb, { \em et al., J. Appl. Phys. } {\bf 115}, 144504 (2014)} can generate tens of thousands of far ultraviolet photons per neutron absorbed. In some cases, up to 30\% of the $\approx$ MeV nuclear reaction energy is channeled into far ultraviolet emission. The far ultraviolet photons are produced by noble-gas excimer radiation, to which the noble gas medium is transparent, facilitating efficient optical detection. We report progress in the development of the Neutron Observatory, http://j.mp/N3utr0n , an absolute neutron detector stationed at the fundamental physics beamline at the NIST Center for Neutron Research. Our reaction initiators consist of arrays of thin films of $^{10}$B and boron-coated vitreous carbon foams \footnote{C. M. Lavelle, {\em et al., Nuc. Inst. Meth. A} {\bf 729}, 346 (2013)} [Preview Abstract] |
Monday, March 2, 2015 11:27AM - 11:39AM |
B21.00002: Shunt-Enhanced, Lead-Driven Bifurcation of Epilayer GaAs based EEC Sensor Responsivity Stuart Solin, Fletcher Werner The results reported here explore the geometric optimization of room-temperature EEC sensor [1] responsivity to applied bias by exploring contact geometry and location. The EEC sensor structure resembles that of a MESFET, but the measurement technique and operation distinguish the EEC sensor significantly; the EEC sensor employs a four-point resistance measurement as opposed to a two-point source-drain measurement and is operated under both forward and reverse bias. Under direct forward bias, the sensor distinguishes itself from a traditional FET by allowing current to be injected from the gate, referred to as a shunt, into the active layer. We show that the observed bifurcation in EEC sensor response to direct reverse bias depends critically on measurement lead location. A dramatic enhancement in responsivity is achieved via a modification of the shunt geometry. A maximum percent change of 130,856{\%} of the four-point resistance was achieved under a direct reverse bias of -1V using an enhanced shunt design, a 325 fold increase over the conventional EEC square shunt design. This result was accompanied by an observed bifurcation in sensor response, driven by a rotation of the four-point measurement leads.\\[4pt] [1] A.K.M. Newaz, et al, Phys Rev B. 79, 195308 (2009). [Preview Abstract] |
Monday, March 2, 2015 11:39AM - 11:51AM |
B21.00003: The GlueX Start Counter Eric Pooser The GlueX experiment will study meson photoproduction with unprecedented precision. This experiment will use the coherent bremsstrahlung technique to produce a 9 GeV linearly polarized photon beam incident on a liquid $\mathrm{H_{2}}$ target. A Start Counter detector has been fabricated to identify the accelerator electron beam buckets, approximately 2 ns apart, and to provide accurate timing information which is used in the level--1 trigger of the experiment. This detector is designed to operate at photon intensities of up to $\mathrm{10^{8}\gamma/s}$ in the coherent peak and provide a timing resolution $\mathrm{<\ 350\ ps}$ so as to provide successful identification of the electron beam buckets to within 99$\%$ accuracy. Furthermore, the Start Counter detector will provide excellent solid angle coverage, $\sim 90 \%\ \mathrm{of}\ 4 \pi\ \mathrm{hermeticity}$, and a high degree of segmentation for background rejection. It consists of a cylindrical array of 30 scintillators with pointed ends that bend towards the beam at the downstream end. Silicon PhotoMultiplier (SiPM) detectors have been selected as the readout system. The physical properties of the Start Counter have been studied extensively. The results of theses studies are discussed. [Preview Abstract] |
Monday, March 2, 2015 11:51AM - 12:03PM |
B21.00004: Alpha-particle emissivity screening of materials used for semiconductor manufacturing Michael Gordon, Kenneth Rodbell Single-Event Upsets (SEU's) in semiconductor memory and logic devices continue to be a reliability issue in modern CMOS devices. SEU's result from deposited charge in the Si devices caused by the passage of ionizing radiation. With technology scaling, the device area decreases, but the critical charge required to flip bits decreases as well. The interplay between both determines how the SEU rate scales with shrinking device geometries and dimensions. In order to minimize the alpha-particle component of SEU, the radiation in the device environment has to be at the Ultra-Low Alpha (ULA) activity levels, e.g. less than 2$\alpha $/khr-cm$^{\mathrm{2}}$. Most detectors have background levels that are significantly larger than that level which makes making these measurements difficult and time consuming. A new class of alpha particle detector, utilizing pulse shape discrimination, is now available which allows one to make measurements quickly with ultra-low detector background. This talk will discuss what is involved in making alpha particle measurements of materials in the ULA activity levels, in terms of calibration, radon adsorption mitigation, the time required for obtaining reasonable statistics and comparisons to other detectors. [Preview Abstract] |
Monday, March 2, 2015 12:03PM - 12:15PM |
B21.00005: Ranged Isotope Detection and Identification Using Gas Ionization Benjamin Graber, Dong Ho Wu Radioactive isotopes produce gamma rays, and the gamma rays ionize gases. Since an isotope has a characteristic gamma energy spectrum, and also gas molecules have characteristic ionization energies, we speculated that the gas ionization rate would uniquely depend on not only the type of isotope but also the type of gas. Our experiments have confirmed these concepts -- the experiments clearly exhibit that different isotopes produce different ion densities in different gases. Utilizing a set of four gas cells with embedded ion counters, it is then possible to construct a standoff nuclear-isotope detection system. This system has demonstrated a standoff detection and identification of isotopes at a substantial distance (more than 5 m) while testing Am, Ba, Co, Cs and Na isotopes of less than 75 uCi activity. Our prototype is cheaper, faster and easier to operate than commercial gamma-ray spectrometers. In this talk our experimental results and theoretical models for gas ionization will be presented. [Preview Abstract] |
Monday, March 2, 2015 12:15PM - 12:27PM |
B21.00006: Broadband Coupling of Microwave Signals to Thin Conductors in Cryogenic Systems Scott Dietrich, William Mayer, Jesse Kanter, Sergey Vitkalov Three techniques are used to determine the microwave (MW) coupling through semi-rigid coaxial lines to samples installed on stages at the bottom of long probes ($\approx 1 m$ or longer) placed in a liquid Helium cryostat. Samples are mounted between the MW delivery line and ground and are placed in parallel with a 50$\Omega$ impedance-matching terminal resistor. One method to determine the delivery of MW signal uses bolometric measurements of the MW power dissipated at the terminal resistor. Another method employs reflection measurements to obtain the reflection coefficient $\Gamma$ of the sample stage, which is sensitive to variations in sample resistance. A third method initially uses the sample itself as a detector of a small, amplitude-modulated MW signal; the resulting variations of sample resistance are then applied as a calibration factor. Each method appears to reliably measure the actual MW signal delivered to the sample. The presented studies focus on two different electronic systems: $GaAs$ quantum wells and $La_{(2-x)}Sr_{_x}CuO$ superconducting films. [Preview Abstract] |
Monday, March 2, 2015 12:27PM - 12:39PM |
B21.00007: ABSTRACT WITHDRAWN |
Monday, March 2, 2015 12:39PM - 12:51PM |
B21.00008: ABSTRACT WITHDRAWN |
Monday, March 2, 2015 12:51PM - 1:03PM |
B21.00009: SAW devices based on novel surface wave excitations Joel Therrien, Lian Dai Surface Acoustic Wave (SAW) devices have applications in radio frequency and microwave filtering as well as highly sensitive sensors. Current SAW design employs the use of an array of electrode pairs, referred to as Inter-Digitated Transducers (IDTs) for creating and receiving surface waves on piezoelectric substrates. The pitch of the electrode pairs along with the properties of the substrate determine the operating frequency. The number of electrode pairs determine the bandwidth of the emitted waves. We will present a novel configuration that eliminates the need for the IDTs and replaces with with a single circular electrode located inside a larger ground ring. This configuration induces drumhead modes. We will show that the resonant frequencies follow the zeros of Bessel functions of the first kind. Applications in RF filtering and mass sensing will be presented. [Preview Abstract] |
Monday, March 2, 2015 1:03PM - 1:15PM |
B21.00010: Multifunctional sensors operating at 300 K based on quasi-ballistic InSb quantum well nanostructures Adam Gilbertson, Dominic Moseley, Mikhail Kustov, Stuart Solin, Lesley Cohen, Simon Bending The high mobility ($\mu )$ of InSb quantum well (QW) heterostructures at 300 K makes them ideally suited for both magnetic and optical sensing. While macroscopic InSb Hall sensors offer the best magnetic sensitivity at 300 K of any material, the operation of sub-micron InSb QW Hall probes have not been reported. Ballistic transport at 300 K in nano-InSb devices was recently described [1]. Here we report the 300 K sensing properties of InSb QW structures fabricated into scanning probe geometries operating in the photoconductive (PC), Hall, and magnetoconductive modes. Sub-micron InSb QW probes exhibit excellent magnetic sensitivity \textless 1$\mu $T/$\surd $Hz and are demonstrated in a scanning Hall probe measurement. InSb QWs exhibit long lived negative photoconductivity in the visible to near-IR for cw excitation, however, significant improvements in dynamic response are found with ac modulated techniques. From spatially resolved PC measurements we determine $\mu \tau $ $\sim$ 3.5 x10$^{-3}$ cm$^{2}$/V. These results provide a benchmark for developing novel InSb QW-metal hybrid nanosensors [2].\\[4pt] [1] A.M. Gilbertson et al., \textit{Appl. Phys.Lett.} \textbf{99}, 242101 (2011)\\[0pt] [2] A.K.M. Newaz et al., \textit{Appl. Phys. Lett.} \textbf{97}, 082105 (2010) [Preview Abstract] |
Monday, March 2, 2015 1:15PM - 1:27PM |
B21.00011: A Simple Instrument for Measuring Surface Forces in Liquids James Hannon, Rudolf Tromp, Richard Haight, Arthur Ellis We have constructed a simple instrument to measure the interaction force between two surfaces in solution, or in vacuum. Specifically, we measure the interaction between a lens and a thin silicon cantilever. Either the lens, or the cantilever (or both) can be coated with the species of interest. When the lens is brought close to the cantilever surface, the force of interaction causes the cantilever to bend. By measuring the deflection as a function of the distance between the lens and cantilever, the long-range interactions between the two surfaces can be determined. Our approach includes three important innovations. First, a commercial lens with a radius of $\sim1$ cm is used for one surface. The relatively large radius of curvature enhances force sensitivity of the method. Second, we use optical interference (Newton's Rings) to determine the distance between lens and cantilever with $\sim1$ nm accuracy. Third, we make use of thin crystalline cantilevers (100 $\mu$m thick) whose elastic properties can be easily measured. We have achieved a force sensitivity $F/R$ better than 0.001 mN/m. I will discuss the theory of operation of the new instrument and describe measurements made on SiO$_2$ and metal oxide surfaces in water. [Preview Abstract] |
Monday, March 2, 2015 1:27PM - 1:39PM |
B21.00012: Particle Imaging, Characterization and Extinction Measurement with Digital Holography Nava Subedi, Matthew Berg This work extends the concept of application of digital holographic microscopy (DHM) from particle imaging to the measurement of photothermally induced particle expansion and energy flow that gives rises to extinction cross section. In this work, a particle is illuminated by a pulsed laser and the interference pattern produced by superposition of particle's forward-scattered wave with the incident wave is recorded by a digital camera. This recorded pattern constitutes a digital hologram which can be numerically processed to get image, photothermally induced expansion and extinction cross-section of the particle. These information of the particle are the basic requirements for the characterization of respirable-sized (1-10 $\mu$m) aerosols particles. [Preview Abstract] |
Monday, March 2, 2015 1:39PM - 1:51PM |
B21.00013: Highly sensitive direct conversion ultrasound interferometer Oleksiy Svitelskiy, John Grossmann, Alexey Suslov Being invented more than fifty years ago, the ultrasonic pulse-echo technique has proven itself as a valuable and indispensable non-destructive tool to explore elastic properties of materials in engineering and scientific tasks. We propose a new design for the instrument based on mass-produced integral microchips. In our design the radiofrequency echo-pulse signal is processed by AD8302 RF gain and phase detector (www.analog.com).Its phase output is linearly proportional to the phase difference between the exciting and response signals. The gain output is proportional to the log of the ratio of amplitudes of the received to the exciting signals. To exclude the non-linear fragments and to enable exploring large phase changes, we employ parallel connection of two detectors, fed by in-phase and quadrature signals respectively. The instrument allowed us exploring phase transitions with precision of $\Delta V/ V\sim 10^{-7}$ ($V$ is the ultrasound speed). The high sensitivity of the logarithmic amplifiers embedded into AD8302 requires good grounding and screening of the receiving circuitry. [Preview Abstract] |
Monday, March 2, 2015 1:51PM - 2:03PM |
B21.00014: Resonance Splitting in RF Cylindrical Cavities with Circular Apertures Luis Martinez Coupling of two RF cylindrical cavities is achieved with the use of a single, thin, circular aperture (iris) located between the two cavities in the transverse plane. A tunable splitting, in which the single resonance splits into a closely spaced doublet for the TE011 mode is experimentally observed. It is found that the frequency spacing of the doublet is related to the circular aperture size. A model based on the analogy of a multi-mirror optical Fabry-Perot cavity, in which the frequency spacing of the doublet is related to the reflection coefficient, is found to be in excellent agreement with the experimental results. Calculation of the reflection coefficient for the circular aperture is performed using the closed form solutions derived from scattering amplitude and circular aperture theory. [Preview Abstract] |
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