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Single SQUID multiplexer for arrays of voltage-biased superconducting bolometers

Description: We describe a frequency domain superconducting quantum interference device (SQUID) multiplexer which monitors a row of low-temperature sensors simultaneously with a single SQUID. Each sensor is ac biased with a unique frequency and all the sensor currents are added in a superconducting summing loop. A single SQUID measures the current in the summing loop, and the individual signals are lock-in detected after the room temperature SQUID electronics. The current in the summing loop is nulled by feedback to eliminate direct crosstalk. In order to avoid the accumulation of Johnson noise in the summing loop, a tuned bandpass filter is inserted in series with each sensor. For a 32-channel multiplexer for Voltage-biased Superconducting Bolometer (VSB) with a time constant {approx}1msec, we estimate that bias frequencies in the range from {approx}500kHz to {approx}600kHz are practical. The major limitation of our multiplexing scheme is in the slew rate of a readout SQUID. We discuss a ''carrier nulling'' technique which could be used to increase the number of sensors in a row or to multiplex faster bolometers by reducing the required slew rate for a readout SQUID.
Date: August 20, 2001
Creator: Yoon, Jongsoo; Clarke, John; Gildemeister, J.M.; Lee, Adrian T.; Myers, M.J.; Richards, P.L. et al.
Partner: UNT Libraries Government Documents Department

Antenna-coupled arrays of voltage-biased superconducting bolometers

Description: We report on the development of antenna-coupled Voltage-biased Superconducting Bolometers (VSBs) which use Transition-edge Sensors (TES). Antenna coupling can greatly simplify the fabrication of large multi-frequency bolometer arrays compared to horn-coupled techniques. This simplification can make it practical to implement 1000+ element arrays that fill the focal plane of mm/sub-mm wave telescopes. We have designed a prototype device with a double-slot dipole antenna, integrated band-defining filters, and a membrane-suspended bolometer. A test chip has been constructed and will be tested shortly.
Date: July 23, 2001
Creator: Myers, Michael J.; Lee, Adrian T.; Richards, P.L.; Schwan, D.; Skidmore, J.T.; Smith, A.D. et al.
Partner: UNT Libraries Government Documents Department

Prospects for CUORE and Latest Results from CUORICINO

Description: CUORE (Cryogenic Underground Observatory for Rare Events) is a proposed next generation experiment designed to search for the neutrinoless DBD of {sup 130}Te using a bolometric technique. The present status of the CUORE is presented along with the latest results from its operating prototype, CUORICINO.
Date: January 5, 2006
Creator: Norman, E B
Partner: UNT Libraries Government Documents Department

Bolometry for divertor characterization and control

Description: Operation of the divertor will provide one of the greatest challenges for ITER. Up to 400 MW of power is expected to be produced in the core plasma which must then be handled by plasma facing components. Power flowing across the separatrix and into the scrape-off-layer (SOL) can lead to a heat flux in the divertor of 30 MW/m{sup 2} if nothing is done to dissipate the power. This peak heat flux must be reduced to 5 MW/m{sup 2} for an acceptable engineering design. The current plan is to use impurity radiation and other atomic processes from intrinsic or injected impurities to spread out the power onto the first wall and divertor chamber walls. It is estimated that 300 MW of radiation in the divertor and SOL will be necessary to achieve this solution. Measurement of the magnitude and distribution of this radiated power with bolometry will be important for understanding and controlling the nER divertor. Present experiments have shown intense regions of radiation both in the divertor near the separatrix and in the X-point region. The task of a divertor bolometer system will be to measure the distribution and magnitude of this radiation. First, radiation measurements can be used for machine protection. Intense divertor radiation will heat plasma facing surfaces that are not in direct view of temperature monitors. Measurement of the radiation distribution will provide information about the power flux to these components. Secondly, a bolometer diagnostic is a basic tool for divertor characterization and understanding. Radiation measurements are important for power accounting, as a cross check for other power diagnostics, and gross characterisation of the plasma behavior. A divertor bolometer system can provide a 2-D measurement of the radiation profile for comparison with theory and modeling. Finally a bolometer system can provide realtime signals for control of ...
Date: October 1, 1995
Creator: Leonard, A.W.; Goetz, J.; Fuchs, C.; Marashek, M.; Mast, F. & Reichle, R.
Partner: UNT Libraries Government Documents Department

Neutron transmutation doped (Ntd) germanium thermistors for sub-Mm bolometer applications

Description: The authors report on recent advances in the development of Neutron Transmutation Doped (NTD) semiconductor thermistors fabricated from germanium of natural and controlled isotopic composition. The near ideal doping uniformity which can be achieved with the NTD process, the device simplicity of NTD Ge thermistors and the high performance of cooled junction field effect transistor (FET) preamplifiers have led to the widespread acceptance of these thermal sensors in many radiotelescopes operating on the ground, on high altitude aircraft and on spaceborne satellites. These features also have made possible the development of efficient bolometer arrays which are beginning to produce exciting results.
Date: September 1, 1996
Creator: Haller, E.E.; Itoh, K.M. & Beeman, J.W.
Partner: UNT Libraries Government Documents Department

Piezoresistive microcantilever optimization for uncooled infrared detection technology

Description: Uncooled infrared sensors are significant in a number of scientific and technological applications. A new approach to uncooled infrared detectors has been developed using piezoresistive microcantilevers coated with thermal energy absorbing materials. Infrared radiation absorbed by the microcantilever detector can be sensitively detected as changes in electrical resistance as function of microcantilever bending. The dynamic range of these devices is extremely large due to measurable resistance change obtained with only nanometer level cantilever displacement. Optimization of geometrical properties for selected commercially available cantilevers is presented. We also present results obtained from a modeling analysis of the thermal properties of several different microcantilever detector architectures.
Date: October 1, 1996
Creator: Rajic, S.; Evans, B.M. III; Oden, P.I.; Datskos, P.G. & Thundat, T.
Partner: UNT Libraries Government Documents Department

An overview of micromachined platforms for thermal sensing and gas detection

Description: Micromachined hotplates, membranes, filaments, and cantilevers have all been used as platforms for thermal sensing and gas detection. Compared with conventional devices, micromachined sensors are characterized by low power consumption, high sensitivity, and fast response time. Much of these gains can be attributed to the size reductions achieved by micromachining. In addition, micromachining permits easy, yet precise tailoring of the heat transfer characteristics of these devices. By simple alterations in device geometry and materials used, the relative magnitudes of radiation, convection and conduction losses and Joule heat gains can be adjusted, and in this way device response can be optimized for specific applications. The free-standing design of micromachined platforms, for example, reduces heat conduction losses to the substrate, thereby making them attractive as low power, fast-response heaters suitable for a number of applications. However, while micromachining solves some of the heat transfer problems typical of conventionally produced devices, it introduces some of its own. These trade-offs will be discussed in the context of several micromachined thermal and gas sensors present in the literature. These include micromachined flow sensors, gas thermal conductivity sensors, pressure sensors, uncooled IR sensors, metal-oxide and catalytic/calorimetric gas sensors. Recent results obtained for a microbridge-based catalytic/calorimetric gas sensor will also be presented as a means of further illustrating the concepts of thermal design in micromachined sensors.
Date: March 1, 1997
Creator: Manginell, R.P.; Smith, J.H. & Ricco, A.J.
Partner: UNT Libraries Government Documents Department

New technologies for the detection of millimeter and submillimeter waves

Description: 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 readout multiplexer.
Date: September 20, 2001
Creator: Richards, P.L.; Clarke, J.; Gildemeister, J.M.; Lanting, T.; Lee, A.T.; Myers, M.J. et al.
Partner: UNT Libraries Government Documents Department

Single SQUID frequency-domain multiplexer for large bolometer arrays

Description: We describe the development of a frequency-domain superconducting quantum interference device (SQUID) multiplexer which monitors a row of low-temperature sensors simultaneously with a single SQUID. Each sensor is ac biased with a unique frequency and all the sensor currents are added in a superconducting summing loop. A single SQUID measures the current in the summing loop, and the individual signals are lock-in detected after the room temperature SQUID electronics. The current in the summing loop is nulled by feedback to eliminate direct crosstalk. We have built an eight-channel prototype and demonstrated channel separation and signal recovery.
Date: August 20, 2001
Creator: Yoon, Jongsoo; Clarke, John; Gildemeister, J.M.; Lee, Adrian T.; Myers, M.J.; Skidmore, J.T. et al.
Partner: UNT Libraries Government Documents Department

Fast resistive bolometry

Description: Resistive bolometry is an accurate, robust, spectrally broadband technique for measuring absolute x-ray fluence and flux. Bolometry is an independent technique for x-ray measurements that is based on a different set of physical properties than other diagnostics such as x-ray diodes, photoconducting detectors, and P-I-N diodes. Bolometers use the temperature-driven change in element resistivity to determine the total deposited energy. The calibration of such a device is based on fundamental material properties and its physical dimensions. The authors describe the use of nickel and gold bolometers to measure x rays generated by high power Z pinches on Sandia`s Saturn and Z accelerators. The Sandia bolometer design described herein has a pulse response of {approximately}1 ns. They describe in detail the fabrication, fielding, and data analysis issues leading to highly accurate x-ray measurements. The fundamental accuracy of resistive bolometry will be discussed.
Date: June 1, 1998
Creator: Spielman, R.B.; Deeney, C.; Fehl, D.L.; Hanson, D.L.; Keltner, N.R.; McGurn, J.S. et al.
Partner: UNT Libraries Government Documents Department

The SSPX Bolometer Systems

Description: There are two bolometry systems on SSPX, one that measures the total radiated power and a 16-channel array to measure the radiation profile. The first collimates the radiation through two slits in the horizontal plane spaced a distance s = 1.2 cm apart as in Fig 1. The slit heights are h = 1/100 th of an inch, and the detector material is behind the second one. The number of electrons generated per photon is proportional to the photon energy (except for a factor of 3-4 enhancement in efficiency in the visible) so that the current of electrons is proportional to the power received. The power is in turn the product of the flux hitting the detector material and the projected perpendicular area of the slab material to the line of sight (which is often at an angle to the slab).
Date: February 1, 2000
Creator: Thomassen, K.I.
Partner: UNT Libraries Government Documents Department

The EBEX Experiment

Description: EBEX is a balloon-borne polarimeter designed to measure the intensity and polarization of the cosmic microwave background radiation. The measurements would probe the inflationary epoch that took place shortly after the big bang and would significantly improve constraints on the values of several cosmological parameters. EBEX is unique in its broad frequency coverage and in its ability to provide critical information about the level of polarized Galactic foregrounds which will be necessary for all future CMB polarization experiments. EBEX consists of a 1.5 m Dragone-type telescope that provides a resolution of less than 8 arcminutes over four focal planes each of 4. diffraction limited field of view at frequencies up to 450 GHz. The experiment is designed to accommodate 330 transition edge bolometric detectors per focal plane, for a total of up to 1320 detectors. EBEX will operate with frequency bands centered at 150, 250, 350, and 450 GHz. Polarimetry is achieved with a rotating achromatic half-wave plate. EBEX is currently in the design and construction phase, and first light is scheduled for 2008.
Date: January 6, 2005
Creator: Oxley, P.; Ade, P.; Baccigalupi, C.; deBernardis, P.; Cho, H-M.; Devlin, M.J. et al.
Partner: UNT Libraries Government Documents Department

Imaging detectors and electronics - A view of the future

Description: Imaging sensors and readout electronics have made tremendous strides in the past two decades. The application of modern semiconductor fabrication techniques and the introduction of customized monolithic integrated circuits have made large scale imaging systems routine in high energy physics. This technology is now finding its way into other areas, such as space missions, synchrotron light sources, and medical imaging. I review current developments and discuss the promise and limits of new technologies. Several detector systems are described as examples of future trends. The discussion emphasizes semiconductor detector systems, but I also include recent developments for large-scale superconducting detector arrays.
Date: June 16, 2004
Creator: Spieler, Helmuth
Partner: UNT Libraries Government Documents Department

SUPERCONDUCTING TRANSITION EDGE BOLOMETER AND NOISE IN THIN FILMS

Description: We report the development of the composite superconducting transition edge bolometer. The temperature sensitive element is an aluminum strip evaporated onto the sapphire substrate. A bismuth film evaporated on the reverse side of the substrate is used to absorb the submillimeter radiation. The noise limitation of the bolometer is calculated. The fabrication and measured performance are described. The best electrical NEP (noise-equivalent-power) obtained is (1.7 {+-} 0.1) x 10{sup -15} WHz{sup -1/2} at 2 Hz at an operating temperature of 1.27 K. This NEP is within a factor of 2 of the thermal noise limit. The effective absorptivity of the bismuth film is measured to be 0.47 {+-} 0.05, and the corresponding detectivity D* is calculated to be (1.1 {+-} 0.1) x 10{sup 14} cm w{sup -1}Hz{sup 1/2}. Suggestions are made for further improvements in sensitivity. The current-dependent noise in thin metal films at the superconducting transition has been further investigated. The measured noise power spectrum of the tin film on sapphire substrate at the superconducting transition is compared with the cosine transforms of the decay curves obtained from step-function and {delta}-function thermal perturbations. The nature of the noise driving term is found to be a random current flowing inside the sample, in agreement with the uncorrelated thermal fluctuation model. This result is consistent with the case of a freely suspended tin fiber at the superconducting transition, but in contrast to the room temperature measurement where the cosine transform of the step-function response gives the noise power spectrum, in agreement with the correlated fluctuation model.
Date: June 1, 1978
Creator: Yeh, Nan-Hsiung
Partner: UNT Libraries Government Documents Department

Passive Spectroscopy Bolometers, Grating- And X-Ray Imaging Crystal Spectrometers

Description: This tutorial gives a brief introduction into passive spectroscopy and describes the working principles of bolometers, a high-resolution grating spectrometer, and a novel X-ray imaging crystal spectrometer, which is of particular interest for profile measurements of the ion temperature and plasma rotation velocity on ITER and future burning plasma experiments.
Date: November 7, 2007
Creator: Bitter, M; Hill, K W; Scott, S; Paul, S; Ince-Cushmann, A; Reinke, M et al.
Partner: UNT Libraries Government Documents Department

On-chip IR spectral sensors by superconducting detector arrays. Semiannual report {number_sign} 2, 18 January 1995--18 July 1995

Description: The overall objective of Phase 2 is to bring this new spectrometer-on-a-chip technology concept to a sufficiently mature stage of development that it can attract commercial support and be carried to market. The specific technical missions of the Phase 2 program are those for the Project Tasks listed below. These mission objectives are: (1) to establish and prove-out the fabrication processing of silicon wafers into arrays of interference-filter plates; (2) to demonstrate that the linear-array HTS detector technology can be scaled up into square arrays of sufficient size and performance to meet the design requirements developed in the Phase 1 effort; (3) to expand the view of the technology so as to see it in a full engineering-systems context, and thus ensure that at the earliest stage possible conflicts can be resolved, thus a systems design can be accomplished that will realistically encompass all the interacting components; (4) to demonstrate, by fabrication and testing, that the components in this systems design can be combined and will deliver the functionality (e.g., spectral region, bandwidth, and resolution) predicted by the design, and in the context of one or two simple emission-line-spectroscopy prototype applications; (5) to identify and resolve conflicts in the design and fabrication methods/processes such that the new spectrometer can meet the desired goal of multiple applications potential. A brief description of each of these 5 tasks is given along with the progress made on each.
Date: September 29, 1995
Creator: Fenner, D.B.; Carangelo, R.M. & Kung, P.J.
Partner: UNT Libraries Government Documents Department

Measurements of divertor impurity concentrations on DIII-D

Description: Carbon emissions in the DIII-D divertor during partial detachment have been measured, and the deduced radiated power and the temporal behavior of the impurity emissions from spectroscopy are in good agreement with bolometer measurements. Effective electron temperatures from line ratios for CIV (9-11 eV) and CIII (6-8 eV) are correlated with DTS measured electron temperatures to determine the spatial location of the carbon radiation zone. During PDD operation, the bulk of the divertor radiation is emitted from CIV near the X- point while deuterium radiation is strongest near the outer strikepoint. The carbon ion concentrations are in the range of 1% - 4% of the electron density.
Date: October 1, 1996
Creator: Wood, R.; Isler, R. C.; Allen, S. L.; Fenstermacher, M. E.; Lasnier, C. J.; Leonard, A. W. et al.
Partner: UNT Libraries Government Documents Department

Diagnostics for the DIII-D radiative divertor

Description: This paper reviews the design of new diagnostics and the modifications to existing diagnostics needed to carry out radiative divertor experiments in DIII-D following installation in late 1996 of a set of baffle structures that will restrict the backflow to the core plasma of neutral deuterium atoms and impurity gases. The divertor slots formed by the new baffle structures will inhibit the easy view of the divertor legs and target plates that the open divertor geometry in DIII-D currently affords. We review a basic set of diagnostics that are needed to demonstrate the reduction of divertor heat loading and radiative dissipation of energy within the divertor. This will include IR cameras, bolometry, foil bolometers, and Langmuir probes. Within the limits of available funding, we will implement a supplemental set of instruments which provide a more detailed understanding of the underlying physical processes. Many existing diagnostics require only re-aiming to provide proper coverage of the initial 23 cm long divertor plasma configuration (X- point to floor distance). Other diagnostics need extensive reconfiguration using in-vessel fiber-optic bundles or high power laser mirrors. The new divertor baffle panels provide a protective shelf for diagnostic hardware mounted underneath them, but the water cooling channels in the panels limit the permissible size of through holes and, thereby, restrict the available views of under-the- baffle diagnostics. The successful resolution of the design and implementation of these diagnostic modifications is dependent on a strong coordination between GA and its many diagnostic collaborators.
Date: October 1, 1995
Creator: Nilson, D.G.; Brooks, N.H.; Smith, J.P. & Snider, R.T.
Partner: UNT Libraries Government Documents Department

Miniature Uncooled Infrared Sensitive Detectors for in Vivo Biomedical Imaging Applications

Description: Broadband infrared (OR) radiation detectors have been developed using miniature, inexpensive, mass produced microcantilevers capable of detecting temperature differences as small as lea(-6) K. Microcantilevers made out of semiconductor materials can be used either as uncurled photon or thermal detectors. Mounted on a probe mm in diameter a number of microcantilevers can be accommodated in the working channel of existing endoscopes for in vivo proximity focus measurements inside the human body.
Date: June 1, 1998
Creator: Datskos, P. G.; Demos, S. G. & Rajic, S.
Partner: UNT Libraries Government Documents Department

UEDGE code comparisons with DIII-D bolometer DATA

Description: This paper describes the work done to develop a bolometer post processor that converts volumetric radiated power values taken from a UEDGE solution, to a line integrated radiated power along chords of the bolometers in the DIII-D tokamak. The UEDGE code calculates plasma physics quantities, such as plasma density, radiated power, or electron temperature, and compares them to actual diagnostic measurements taken from the scrape off layer (SOL) and divertor regions of the DIII-D tokamak. Bolometers are devices measuring radiated power within the tokamak. The bolometer interceptors are made up of two complete arrays, an upper array with a vertical view and a lower array with a horizontal view, so that a two dimensional profile of the radiated power may be obtained. The bolometer post processor stores line integrated values taken from UEDGE solutions into a file in tabular format. Experimental data is then put into tabular form and placed in another file. Comparisons can be made between the UEDGE solutions and actual bolometer data. Analysis has been done to determine the accuracy of the plasma physics involved in producing UEDGE simulations.
Date: January 1, 1995
Creator: Daniel, J. M.
Partner: UNT Libraries Government Documents Department

A rad-hard, steady state, digital imaging bolometer system for ITER

Description: The concept and design of a new type of bolometer system which can function with excellent spatial resolution and good time resolution in the next generation of long-pulse (or steady-state), harsh-neutron environment fusion plasmas, is outlined. It uses a cooled pinhole camera design, employing a robust, passive, segmented radiation absorber, cooled from the back-side. Infrared emission from the absorber`s front surface is relayed by metal mirror optics to a shielded, high-resolution IR video camera with {+-} 0.01 C temperature resolution. It can make thousands of simultaneous ``pixel`` measurements at up to 50--60 Hz, without any signal wires through the vacuum interface.
Date: September 1, 1995
Creator: Wurden, G.A.
Partner: UNT Libraries Government Documents Department

Quantum effects in the hot electron microbolometer

Description: The theory of the hot electron microbolometer proposed by Nahum et al. assumed that the photon energy is thermalized in the electrons in the Cu absorber before relaxing to the lattice. Since the photons initially excite individual electrons to K{omega}>>k{sub B}T, however, direct relaxation of these hot electrons to phonons must also be considered. Theoretical estimates suggest that this extra relaxation channel increases the effective thermal conductance for K{omega}>>k{sub B}T and influences bolometer noise. Calculations of these effects are presented which predict very useful performance both for ground-based and spacebased astronomical photometry at millimeter and submillimeter wavelengths.
Date: October 1, 1994
Creator: Tang, A. & Richards, P.L.
Partner: UNT Libraries Government Documents Department