Bulletin of the American Physical Society
APS March Meeting 2013
Volume 58, Number 1
Monday–Friday, March 18–22, 2013; Baltimore, Maryland
Session N46: Detectors, Sensors, and Transducers |
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Sponsoring Units: GIMS Chair: Brad Ramshaw, Los Alamos National Laboratory Room: Hilton Baltimore Holiday Ballroom 5 |
Wednesday, March 20, 2013 11:15AM - 11:27AM |
N46.00001: Sub-diffraction Position Determination with Four Laser Diodes for Tracking/Trapping a Single Molecule James A. Germann, Brian K. Canfield, Jason K. King, Lloyd M. Davis Prolonged observation of single biological molecules by overcoming diffusion can reveal interesting new properties. Observation times may be increased by physically confining a particle, but this often leads to interactions that affect molecular properties. Another way of increasing observation time is to trap a single molecule in solution three-dimensionally. However, optimal trapping of single particles relies on rapid determination of particle position for feedback to counteract Brownian diffusion. In our experiment, a tetrahedral region with foci located at the vertices is created by combining four modulated 635 nm laser diodes with three beam splitters. Fluorescence is measured with a single-photon avalanche diode and separated into bins corresponding to each excitation focus. A maximum-likelihood estimation algorithm is used to determine particle position with sub-diffraction precision in real time. To test the tracking capability of the four-focus setup, fluorescently labeled latex beads were tracked in an aqueous glycerol solution. Two setups, a piezoelectric stage and a three-dimensional electrokinetic trap, are being implemented to maintain a single fluorescent latex bead in the middle of the tetrahedral region. [Preview Abstract] |
Wednesday, March 20, 2013 11:27AM - 11:39AM |
N46.00002: ac-Calorimetric Measurements of Transverse Thermal Conductivity Hao Zhang, Joseph Brill We are developing an ac-calorimetric technique, heating one surface of a thin sample with oscillating power and measuring the temperature oscillations on the opposite surface, to measure the thermal conductivity of solids. While the temperature oscillations are inversely proportional to the heat capacity at low frequencies, at higher frequencies the response is limited by the transverse thermal diffusivity. Because of the response times of thermometers and the fact that the magnitude of the temperature oscillation varies inversely with frequency, this technique is most useful for materials with low thermal conductivities, such as the interlayer conductivity in layered materials. We will show results on ``standard'' materials (teflon, sapphire) as well as the layered organic semiconductors, rubrene and TIPS-pentacene. [Preview Abstract] |
Wednesday, March 20, 2013 11:39AM - 11:51AM |
N46.00003: Thermal expansion measurement using optical grating diffraction shifts Tran Vinh Son, Mohamed Touaibia, Alain Hache We demonstrate a novel optical method for accurately measuring thermal expansion in materials. When an optical grating expands or contracts, the Bragg diffraction condition is altered, and the diffracted beams undergo angular shifts. Using a diffracted laser beam, we demonstrate that this effect can be used to measure expansion coefficients as small as 10$^{-6}$ C$^{-1}$. By patterning samples of PMMA and chitosan with grating lines, we measure their thermal expansion coefficients by heating the sample by only a few degrees Celsius. The method can be generalized to opaque materials by texturing the surface and measuring diffraction in reflection. A theory is presented to determine the ideal experimental conditions and the limits of accuracy. [Preview Abstract] |
Wednesday, March 20, 2013 11:51AM - 12:03PM |
N46.00004: Properties of Holmium Implanted Gold Films and a YSias Absorbers in TES Microcalorimeters for Holmium Neutrino Mass Experiment Krishna Prasai, E. Alaves, D. Bagliani, N. Barradas, M. Biasotti, M. Galeazzi, F. Gatti, P. Manfrinetti, M.R. Gomes, Y. Uprety, S. Yanardag The electron capture decay of Ho-163 can be used for the direct measurement of the electron neutrino mass with Transition Edge Sensor (TES) microcalorimeters. A major requirement for a microcalorimetric holmium experiment is to embed the source in the detector absorber. A logical choice would be to implant the isotope into a regular gold absorber, assuming that it does not change the absorber properties. As an alternate option, since most chemical processes to extract the Ho-163 isotope after fabrication involve yttrium based compounds, it could be possible to use a yttrium compound as absorber, rather than just as an intermediate step. We have studied the properties of gold films implanted with holmium and erbium (which is present due to source manufacturing) and Yttrium silicide (YSi) in the working temperature range of the TES microcalorimeters (90-300 mK).In this paper we present the results of our investigation [Preview Abstract] |
Wednesday, March 20, 2013 12:03PM - 12:15PM |
N46.00005: Quasiparticle diffusion in Al film and transmission with an Al/W interface Jeffrey Yen, Paul Brink, Blas Cabrera, Matt Cherry, Matt Pyle, Peter Redl, Astrid Tomada, Betty Young The Cryogenic Dark Matter Search (CDMS) experiment uses both high-purity Si and Ge crystals to directly search for Weakly Interacting Massive Particles (WIMPs). These detectors simultaneously measure the ionization and phonon energy produced by particle interactions. This talk will focus on experiments performed with a separate set of test devices fabricated to study the fundamental physics of the CDMS phonon sensors. In our test experiments, an $^{55}$Fe source was used to excite a NaCl reflector, producing 2.6 keV x-rays that hit our test devices after passing through a collimator. The devices under study consisted of a 250 $\mu$ m wide x 350 $\mu$ m long Al absorber film (300 nm thick) coupled to two 250 $\mu$ m x 250 $\mu$ m (40 nm thick) W transition edge sensors (TESs), one at each end of the Al film. The impinging x-rays break Cooper pairs in the Al film, producing quasiparticles that we detect as they propagate into the W TESs. We studied the diffusion of these quasiparticles, trapping in the Al film, and their transmission probability at the Al/W interfaces. Results from our precision experiments will be presented in this talk. These results are also being used to further optimize the design of SuperCDMS detectors for a proposed 100 kg scale dark matter search. [Preview Abstract] |
Wednesday, March 20, 2013 12:15PM - 12:27PM |
N46.00006: Depolarization factors in electro-optic crystals and their effects in sensing applications Anthony Garzarella Many applications involving electric field measurements require sensors that are compact and non-intrusive. This is especially true for tests inside small cavities, where conventional antennas and metallic probes are not only too bulky, but will also perturb the very fields they measure. Electro-optic (EO) sensors are ideal in such situations, because they are small and all-dielectric. Despite this, antennas are still predominantly used due to their higher sensitivity (2-3 orders of magnitude). Therefore to make EO sensors viable, sensitivity must be improved. The customary figure of merit (FOM) is the ratio of the EO coefficient to the dielectric constant. LiNbO$_{\mathrm{3}}$ and similar crystals are preferred because of their large FOMs. In these crystals, the EO tensor is such that a transverse configuration must be used where the E-field and laser path are orthogonal. In this report, we demonstrate that sensors based on longitudinal crystals (E-field and laser collinear) can have greater sensitivities, even though their FOMs are substantially lower due to depolarization effects that enhance internal fields. Explicit examples are shown, and the practical limits in making EO sensors more competitive with conventional antennas will be discussed. [Preview Abstract] |
Wednesday, March 20, 2013 12:27PM - 12:39PM |
N46.00007: Stress reconfigurable tunable magnetoelectric resonators as magnetic sensors Jillian Kiser, Peter Finkel, Christophe Dolabdjian Magnetoelectric multiferroic materials are extremely attractive due to their potential in sensing, filtering and energy transduction applications. We report a magnetoelastic effect in doubly-clamped ferromagnetic magnetostrictive Metglas resonators, as well as the magnetic field dependence of the resonance frequency as a function of uniaxial stress. Magnetostrictive strain results in a resonance frequency shift when the resonator is exposed to a magnetic field. The resonance frequency can be tracked in real time as a function of magnetic field bias using a feedback loop based on the quadrature of the excited motion. This magnetically reconfigurable resonance response can be used as a simple, tunable, magnetoelectric (ME) magnetic field sensor. The effect of sample pre-tension on the field dependent magnetostrictive constant and the sensor sensitivity is examined, and the resolution of such a sensor is estimated. [Preview Abstract] |
Wednesday, March 20, 2013 12:39PM - 12:51PM |
N46.00008: Disruptive Approach Towards 10nm Spatial Resolution In X-PEEM Using Diamondoids Hendrik Ohldag, Hitoshi Ishiwata, Yves Acremann, Olav Hellwig, Peter Schreiner, Nick Melosh, Zhi-Xun Shen Diamondoids are unique molecular nano-materials with diamond structure and fascinating new properties such as negative electron affinity (NEA) and short electron mean free paths. A thin layer of diamondoids deposited on a cathode is able to act as an electron monochromator, reducing the energy spread of photo-emitted electrons from a surface. This property can be applied effectively to improve the spatial resolution in x-ray photoemission electron microscopy (X-PEEM), which is limited by chromatic aberration of the electron optics. In this talk we will present X-PEEM measurements reaching the technological relevant spatial resolution of 10-nm without the need of expensive and complex corrective optics. Our results provide a simple approach to image surface chemical and magnetic information at nanometer scales by employing diamondoid. [1] H. Ishiwata et al. Appl. Phys. Lett. \textbf{101}, 163101 (2012) [Preview Abstract] |
Wednesday, March 20, 2013 12:51PM - 1:03PM |
N46.00009: Energy Analysis in Near Field-Emission SEM Lorenzo Giuseppe De Pietro, Danilo Andra Zanin, Hugo Cabrera, Urs Ramsperger, Danilo Pescia, Mehmet Erbudak In Near Field-Emission Scanning Electron Microscopy (NFESEM) cold field emitted electrons from a sharp polycrystalline W-tip are the source of a primary electron beam. The applied voltage for field-emission accelerates these electrons up to some tens of eV. After having interacted with the sample, secondary and backscattered electrons are detected, while an STM controller is used to scan the tip at a constant average distance ($10$ to $20$ nm) from the sample surface. This technique has been used for topography images on various metals and semiconductors achieving nm lateral resolution. In case of a W(110) surface covered by Fe islands a chemical contrast was observed. We recently added an energy analysis of the electrons used for imaging. The energy distribution of this electrons from the sample shows presence of both secondary and back scattered electrons. The ratio of the two groups of electrons may vary for different distances and energies. In view of including spin polarization analysis, we are currently working to optimize the secondary electron yield. [Preview Abstract] |
Wednesday, March 20, 2013 1:03PM - 1:15PM |
N46.00010: Scale invariance of a diode-like tunnel junction Hugo Cabrera, Danilo Andrea Zanin, Lorenzo Giuseppe De Pietro, Thomas Michaels, Peter Thalmann, Urs Ramsperger, Alessandro Vindigni, Danilo Pescia In Near Field-Emission SEM (NFESEM), electrostatic considerations favor a diode-like tunnel junction consisting of an atomic-sized source mounted at the apex of a thin wire placed at nanometric distances from a collector. The quantum mechanical tunnel process, instead, can provide a barrier toward miniaturization. In the first place, it deteriorates the generation of electrons by introducing non-linearities within the classically forbidden zone that exponentially increase with decreasing sizes. In addition, in the direct tunnelling regime, i.e. when the distance between emitter and collector $d$ approaches the subnanometer range, a characteristic length appears, making the cross-over from the (almost) scale-invariant electric-field assisted regime to the essentially different STM-regime. We have observed that the experimental data relating the current $I$ to the two experimental variables $V$ (bias voltage between tip and collector) and $d$ can be made (almost) collapse onto a ``scaling curve'' relating $I$ to the single variable $V\cdot d^{-\lambda}$, $\lambda$ being some exponent that depends solely on the geometry of the junction. This scaling property can be used to highlight non-linear aspects of the quantum mechanical tunnelling process. [Preview Abstract] |
Wednesday, March 20, 2013 1:15PM - 1:27PM |
N46.00011: Particle acceleration on a chip: A laser-driven micro-accelerator for research and industry R.B. Yoder, G. Travish Particle accelerators are conventionally built from radio-frequency metal cavities, but this technology limits the maximum energy available and prevents miniaturization. In the past decade, laser-powered acceleration has been intensively studied as an alternative technology promising much higher accelerating fields in a smaller footprint and taking advantage of recent advances in photonics. Among the more promising approaches are those based on dielectric field-shaping structures. These ``dielectric laser accelerators'' (DLAs) scale with the laser wavelength employed and can be many orders of magnitude smaller than conventional accelerators; DLAs may enable the production of high-intensity, ultra-short relativistic electron bunches in a chip-scale device. When combined with a high-$Z$ target or an optical-period undulator, these systems could produce high-brilliance x-rays from a breadbox-sized device having multiple applications in imaging, medicine, and homeland security. In our research program we have developed one such DLA, the Micro-Accelerator Platform (MAP). We describe the fundamental physics, our fabrication and testing program, and experimental results to date, along with future prospects for MAP-based light-sources and some remaining challenges. [Preview Abstract] |
Wednesday, March 20, 2013 1:27PM - 1:39PM |
N46.00012: Webcam science -- Can a useful transmission ion microscope be built for less than {\$}1000? Arthur Pallone, Patrick Barnes Scientists and engineers build simple, low-cost, webcam-based instruments for use in many disciplines. Analysis of the optical signal received through the three broadband color filters -- red, green and blue -- form the basis of many of those instruments. The CMOS sensors in webcam pixels also produce signals in response to ionizing radiations -- such as alpha particles from a radioactive source. Simple alpha radiography has been demonstrated with an alpha source and a webcam modified to expose the sensors. The performance of a direct imaging transmission ion microscope built from such a modified webcam and a commercially available polonium-210 antistatic device mounted to an optics rail is analyzed. Potential uses and limitations of the microscope are also discussed. [Preview Abstract] |
Wednesday, March 20, 2013 1:39PM - 1:51PM |
N46.00013: Design and implementation of a wireless passive microsensor for methanol detection Diego Sanz, Walter Rosas, Edgar Unigarro, Watson Vargas, Fredy Segura-Quijano Methanol is a public health concern due to its toxicity, characterized by metabolic acidosis and blindness, among others. The third world population affected by the exposure to this compound is increasing, mainly due to the consumption of illicit distilled or adulterated alcoholic beverages. Although methanol is naturally present in some alcoholic drinks, the maximum allowed concentration cannot exceed 10 g of methanol per liter of anhydrous alcohol (0.4\% (v/v) at 40\% of ethanol) according to the general EU limit. A wireless passive microsensor was designed to detect small amounts of methanol at 40\% of alcoholic dissolutions. The sensor consists of a planar inductor in series with an interdigital capacitor that changes its capacitance with the solution's dielectric constant. An antenna is used to readout the real part of the impedance to obtain the resonant frequencies for different amounts of methanol in the solution. The aim of this work was to develop a low cost wireless sensor with the capability to detect concentrations of at least 0.4\% (v/v) of methanol in a 40\% of alcoholic solution. The results obtained show variations of 403 kHz in the resonant frequency for changes of 0.2\% (v/v) on the concentration of methanol in a 40\% alcoholic ethanol-based solution. [Preview Abstract] |
Wednesday, March 20, 2013 1:51PM - 2:03PM |
N46.00014: Phase conjugate Sagnac interferometer based on degenerate four-wave mixing using evanescent field Lijuan Gu, Zizhao Gan We propose a phase conjugate Sagnac interferometer based on degenerate four-wave mixing using evanescent field to improve the performance of fiber optic gyroscope. Degenerate four-wave mixing relies on interaction between two pump waves and evanescent fields surrounding the waveguide. By decreasing the radius of the waveguide, we can get sufficient fraction of the evanescent field. Degenerate four-wave mixing process can generate phase conjugated wave of the signal field and they are coherent intrinsically. In a rotational system, the two conjugated waves possess phase difference that is proportional to the rotational velocity of the system. So by measuring the phase difference, we can get the rotational information of the system and this method can avoids noises caused by wave propagation in fiber. [Preview Abstract] |
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