Science.gov

Sample records for 83mkr calibration source

  1. Calibrated vapor generator source

    DOEpatents

    Davies, J.P.; Larson, R.A.; Goodrich, L.D.; Hall, H.J.; Stoddard, B.D.; Davis, S.G.; Kaser, T.G.; Conrad, F.J.

    1995-09-26

    A portable vapor generator is disclosed that can provide a controlled source of chemical vapors, such as, narcotic or explosive vapors. This source can be used to test and calibrate various types of vapor detection systems by providing a known amount of vapors to the system. The vapor generator is calibrated using a reference ion mobility spectrometer. A method of providing this vapor is described, as follows: explosive or narcotic is deposited on quartz wool, placed in a chamber that can be heated or cooled (depending on the vapor pressure of the material) to control the concentration of vapors in the reservoir. A controlled flow of air is pulsed over the quartz wool releasing a preset quantity of vapors at the outlet. 10 figs.

  2. Calibrated vapor generator source

    DOEpatents

    Davies, John P.; Larson, Ronald A.; Goodrich, Lorenzo D.; Hall, Harold J.; Stoddard, Billy D.; Davis, Sean G.; Kaser, Timothy G.; Conrad, Frank J.

    1995-01-01

    A portable vapor generator is disclosed that can provide a controlled source of chemical vapors, such as, narcotic or explosive vapors. This source can be used to test and calibrate various types of vapor detection systems by providing a known amount of vapors to the system. The vapor generator is calibrated using a reference ion mobility spectrometer. A method of providing this vapor is described, as follows: explosive or narcotic is deposited on quartz wool, placed in a chamber that can be heated or cooled (depending on the vapor pressure of the material) to control the concentration of vapors in the reservoir. A controlled flow of air is pulsed over the quartz wool releasing a preset quantity of vapors at the outlet.

  3. Chromium-51 calibrating neutrino source

    SciTech Connect

    Demchenko, N.F.; Karasev, V.I.; Karelin, E.A.

    1993-12-31

    The problem for measurement of the sun neutrino flux is resolved at the specially made Baksansk neutrino telescope and calls for calibration of registration system. For this a man made neutrino source is required with the known yield of particles and intensity comparable with the intensity of the measured subject. The most suitable radionuclide for production of this source is chromium-51 the radionuclide decay of which is accompanied with neutrino radiation. At the Research Institute of Atomic Reactors (in Dimitrovgrad) the production technology is developed as well as the closed chromium-51 neutrino source is made of 4 x 10{sup 5} Ci activity. The parts of active source made in the form of core of metallic isotope-enriched chromium were irradiated in the high flux neutron trap of the SM-2 reactor. The sources were subsequently assembled at the shield cells with remote equipment application. The source was certificated as a special form radioactive material. Due to low half-life of chromium-51 (T 1/2 - 27 hours) all the operations on assembly, certification and delivery of source to the Baksansk Laboratory were performed at the earliest possible date (less than 3 days).

  4. Multigamma-ray calibration sources

    SciTech Connect

    Meyer, R.A.; Massey, T.N.

    1983-05-01

    We have calibrated a self-consistent set of multigamma-ray standards using the automated multi-spectrometry ..gamma..-ray counting facility at LLNL's Nuclear Chemistry Division. Pure sources of long-lived activity were produced by mass separation and/or chemical purification. The sources were counted individually and in combination on several different calibrated spectrometer systems. These systems utilize various detectors ranging from small (x-ray) detectors to large volume high-purity Ge detectors. This has allowed the use of the most ideal individual detector-efficiency characteristics for the determination of the relative ..gamma..-ray intensities. Precise energy measurements, reported earlier (Meyer, 1976) have been performed by an independent method. Both the energy and ..gamma..-ray-emission probabilities determined compare well with independently established values such as the recent ICRM intercomparison of /sup 152/Eu. We discuss our investigations aimed at resolving the shape of the efficiency response function up to 10 MeV for large volume Ge(Li) and high-purity Ge detectors. Recent results on the ..gamma..-ray-emission probabilities per decay for /sup 149/Gd and /sup 168/Tm multigamma-ray sources are discussed. For /sup 168/Tm, we deduce a 0.01% ..beta../sup -/ branch to the 87.73-keV level in /sup 168/Yb rather than the previous value which was a factor of 200 greater. In addition, we describe current cooperative efforts aimed at establishing a consistent set of data for short-lived fission products. Included are recent measurements on the bromine fission products with ..gamma.. rays up to 7 MeV.

  5. Calibration of Photon Sources for Brachytherapy

    NASA Astrophysics Data System (ADS)

    Rijnders, Alex

    Source calibration has to be considered an essential part of the quality assurance program in a brachytherapy department. Not only it will ensure that the source strength value used for dose calculation agrees within some predetermined limits to the value stated on the source certificate, but also it will ensure traceability to international standards. At present calibration is most often still given in terms of reference air kerma rate, although calibration in terms of absorbed dose to water would be closer to the users interest. It can be expected that in a near future several standard laboratories will be able to offer this latter service, and dosimetry protocols will have to be adapted in this way. In-air measurement using ionization chambers (e.g. a Baldwin—Farmer ionization chamber for 192Ir high dose rate HDR or pulsed dose rate PDR sources) is still considered the method of choice for high energy source calibration, but because of their ease of use and reliability well type chambers are becoming more popular and are nowadays often recommended as the standard equipment. For low energy sources well type chambers are in practice the only equipment available for calibration. Care should be taken that the chamber is calibrated at the standard laboratory for the same source type and model as used in the clinic, and using the same measurement conditions and setup. Several standard laboratories have difficulties to provide these calibration facilities, especially for the low energy seed sources (125I and 103Pd). Should a user not be able to obtain properly calibrated equipment to verify the brachytherapy sources used in his department, then at least for sources that are replaced on a regular basis, a consistency check program should be set up to ensure a minimal level of quality control before these sources are used for patient treatment.

  6. Artificial calibration source for ALMA radio interferometer

    NASA Astrophysics Data System (ADS)

    Kiuchi, Hitoshi; Hills, Richard; Whyborn, Nicholas D.; Asayama, Shinichiro; Sakamoto, Seiichi; Iguchi, Satoru; Corder, Stuartt A.

    2016-07-01

    The ALMA (Atacama Large Millimeter/submillimeter Array) radio interferometer has some different types of antennas which have a variation of gain and leakages across the primary beam of an individual antenna. We have been developing an artificial calibration source which is used for compensation of individual difference of antennas. In a high-frequency antenna, using astronomical sources to do calibration measurement would be extremely time consuming, whereas with the artificial calibration source becomes a realistic possibility. Photonic techniques are considered to be superior to conventional techniques based on electronic devices in terms of wide bandwidth and high-frequency signals. Conversion from an optical signal to a millimeter/sub-millimeter wave signal is done by a photo-mixer.

  7. Development of the PROSPECT Source Calibration System

    NASA Astrophysics Data System (ADS)

    Bykadorova, Arina; Prospect Collaboration

    2016-09-01

    PROSPECT, the Precision Reactor Oscillation and Spectrum Experiment, is a short-baseline antineutrino experiment consisting of a movable liquid scintillator detector operated near Oak Ridge National Laboratory's High Flux Isotope Reactor (HFIR). PROSPECT is designed to make a precise measurement of the antineutrino spectrum emitted from 235U fissions in a highly-enriched uranium reactor core, and to probe for eV-scale sterile neutrinos by examining neutrino oscillations at a distance of 7-12 m from the reactor. These measurements will address the observed reactor anomalies: the deficit in the reactor flux and the deviation in the spectral shape. PROSPECT consists of a 2-ton segmented liquid scintillator detector. Each segment is read out with two photomultipliers. Energy response and position reconstruction are calibrated using radioactive gamma and neutron sources. We have developed a retractable source deployment system that allows the placement of sources along the length of the detector segments and tested it using PROSPECT-50, a 50-liter detector prototype consisting of two segments. We will present the design of the PROSPECT source calibration system and results from PROSPECT-50. Wright Laboratory, Department of Physics, Yale University, New Haven, CT, USA.

  8. 21 CFR 892.1400 - Nuclear sealed calibration source.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nuclear sealed calibration source. 892.1400... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1400 Nuclear sealed calibration source. (a) Identification. A nuclear sealed calibration source is a device that consists of an...

  9. 21 CFR 892.1400 - Nuclear sealed calibration source.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Nuclear sealed calibration source. 892.1400... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1400 Nuclear sealed calibration source. (a) Identification. A nuclear sealed calibration source is a device that consists of an...

  10. 21 CFR 892.1400 - Nuclear sealed calibration source.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Nuclear sealed calibration source. 892.1400... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1400 Nuclear sealed calibration source. (a) Identification. A nuclear sealed calibration source is a device that consists of an...

  11. 21 CFR 892.1400 - Nuclear sealed calibration source.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Nuclear sealed calibration source. 892.1400... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1400 Nuclear sealed calibration source. (a) Identification. A nuclear sealed calibration source is a device that consists of an...

  12. 21 CFR 892.1400 - Nuclear sealed calibration source.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Nuclear sealed calibration source. 892.1400... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1400 Nuclear sealed calibration source. (a) Identification. A nuclear sealed calibration source is a device that consists of an...

  13. The Euclid near-infrared calibration source

    NASA Astrophysics Data System (ADS)

    Holmes, Rory; Bizenberger, Peter; Krause, Oliver; Schweitzer, Mario; Glauser, Adrian M.

    2010-07-01

    The Euclid dark energy mission is currently competing in ESA's Cosmic Vision program. Its imaging instrument, which has one visible and one infrared channel, will survey the entire extragalactic sky during the 5 year mission. The near-infrared imaging photometer (NIP) channel, operating in the ~0.92 - 2.0 μm spectral range, will be used in conjunction with the visible imaging channel (VIS) to constrain the nature of dark energy and dark matter. To meet the stringent overall photometric requirement, the NIP channel requires a dedicated on-board flat-field source to calibrate the large, 18 detector focal plane. In the baseline concept a 170 mm Spectralon diffuser plate, mounted to a pre-existing shutter mechanism outside the channel, is used as a flat-field calibration target, negating the need for an additional single-point-failure mechanism. The 117 × 230 mm focal plane will therefore be illuminated through all of the channel's optical elements and will allow flat-field measurements to be taken in all wavelength bands. A ring of low power tungsten lamps, with custom reflecting elements optimized for optical performance, will be used to illuminate the diffuser plate. This paper details the end-to-end optical simulations of this concept, a potential mechanical implementation and the initial tests of the proposed key components.

  14. The Herschel-PACS photometer calibration. Point-source flux calibration for scan maps

    NASA Astrophysics Data System (ADS)

    Balog, Zoltan; Müller, Thomas; Nielbock, Markus; Altieri, Bruno; Klaas, Ulrich; Blommaert, Joris; Linz, Hendrik; Lutz, Dieter; Moór, Attila; Billot, Nicolas; Sauvage, Marc; Okumura, Koryo

    2014-07-01

    This paper provides an overview of the PACS photometer flux calibration concept, in particular for the principal observation mode, the scan map. The absolute flux calibration is tied to the photospheric models of five fiducial stellar standards ( α Boo, α Cet, α Tau, β And, γ Dra). The data processing steps to arrive at a consistent and homogeneous calibration are outlined. In the current state the relative photometric accuracy is ˜2 % in all bands. Starting from the present calibration status, the characterization and correction for instrumental effects affecting the relative calibration accuracy is described and an outlook for the final achievable calibration numbers is given. After including all the correction for the instrumental effects, the relative photometric calibration accuracy (repeatability) will be as good as 0.5 % in the blue and green band and 2 % in the red band. This excellent calibration starts to reveal possible inconsistencies between the models of the K-type and the M-type stellar calibrators. The absolute calibration accuracy is therefore mainly limited by the 5 % uncertainty of the celestial standard models in all three bands. The PACS bolometer response was extremely stable over the entire Herschel mission and a single, time-independent response calibration file is sufficient for the processing and calibration of the science observations. The dedicated measurements of the internal calibration sources were needed only to characterize secondary effects. No aging effects of the bolometer or the filters have been found. Also, we found no signs of filter leaks. The PACS photometric system is very well characterized with a constant energy spectrum νF ν = λF λ = const as a reference. Colour corrections for a wide range of sources SEDs are determined and tabulated.

  15. Characterisation of a protection level Am-241 calibration source

    NASA Astrophysics Data System (ADS)

    Bass, G. A.; Rossiter, M. J.; Williams, T. T.

    1992-11-01

    The various measurements involved in the commissioning process of an Am-241 radioactive source and transport mechanisms to be used for protection level calibration work are detailed. The source and its handling mechanisms are described and measurements to characterize the resultant gamma ray beam are described. For the beam measurements, the inverse square law is investigated and beam uniformity is assessed. A trial calibration of ionization chambers is described. The Am-241 irradiation facility is concluded to be suitable for calibrating secondary standards as part of the calibration service offered for protection level instruments. The umbra part of beam is acceptably uniform for a range of chambers and the measurements obtained were predictable and consistent. This quality will be added to the range of qualities offered as part of the protection level secondary standard calibration service.

  16. Common Calibration Source for Monitoring Long-term Ozone Trends

    NASA Technical Reports Server (NTRS)

    Kowalewski, Matthew

    2004-01-01

    Accurate long-term satellite measurements are crucial for monitoring the recovery of the ozone layer. The slow pace of the recovery and limited lifetimes of satellite monitoring instruments demands that datasets from multiple observation systems be combined to provide the long-term accuracy needed. A fundamental component of accurately monitoring long-term trends is the calibration of these various instruments. NASA s Radiometric Calibration and Development Facility at the Goddard Space Flight Center has provided resources to minimize calibration biases between multiple instruments through the use of a common calibration source and standardized procedures traceable to national standards. The Facility s 50 cm barium sulfate integrating sphere has been used as a common calibration source for both US and international satellite instruments, including the Total Ozone Mapping Spectrometer (TOMS), Solar Backscatter Ultraviolet 2 (SBUV/2) instruments, Shuttle SBUV (SSBUV), Ozone Mapping Instrument (OMI), Global Ozone Monitoring Experiment (GOME) (ESA), Scanning Imaging SpectroMeter for Atmospheric ChartographY (SCIAMACHY) (ESA), and others. We will discuss the advantages of using a common calibration source and its effects on long-term ozone data sets. In addition, sphere calibration results from various instruments will be presented to demonstrate the accuracy of the long-term characterization of the source itself.

  17. Results from source-based and detector-based calibrations of a CLARREO calibration demonstration system

    NASA Astrophysics Data System (ADS)

    Angal, Amit; McCorkel, Joel; Thome, Kurt

    2016-09-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission is formulated to determine long-term climate trends using SI-traceable measurements. The CLARREO mission will include instruments operating in the reflected solar (RS) wavelength region from 320 nm to 2300 nm. The Solar, Lunar for Absolute Reflectance Imaging Spectroradiometer (SOLARIS) is the calibration demonstration system (CDS) for the reflected solar portion of CLARREO and facilitates testing and evaluation of calibration approaches. The basis of CLARREO and SOLARIS calibration is the Goddard Laser for Absolute Measurement of Response (GLAMR) that provides a radiance-based calibration at reflective solar wavelengths using continuously tunable lasers. SI-traceability is achieved via detector-based standards that, in GLAMR's case, are a set of NIST-calibrated transfer radiometers. A portable version of the SOLARIS, Suitcase SOLARIS is used to evaluate GLAMR's calibration accuracies. The calibration of Suitcase SOLARIS using GLAMR agrees with that obtained from source-based results of the Remote Sensing Group (RSG) at the University of Arizona to better than 5% (k=2) in the 720-860 nm spectral range. The differences are within the uncertainties of the NIST-calibrated FEL lamp-based approach of RSG and give confidence that GLAMR is operating at <5% (k=2) absolute uncertainties. Limitations of the Suitcase SOLARIS instrument also discussed and the next edition of the SOLARIS instrument (Suitcase SOLARIS- 2) is expected to provide an improved mechanism to further assess GLAMR and CLARREO calibration approaches.

  18. Spectrally and Radiometrically Stable, Wideband, Onboard Calibration Source

    NASA Technical Reports Server (NTRS)

    Coles, James B.; Richardson, Brandon S.; Eastwood, Michael L.; Sarture, Charles M.; Quetin, Gregory R.; Porter, Michael D.; Green, Robert O.; Nolte, Scott H.; Hernandez, Marco A.; Knoll, Linley A.

    2013-01-01

    The Onboard Calibration (OBC) source incorporates a medical/scientific-grade halogen source with a precisely designed fiber coupling system, and a fiber-based intensity-monitoring feedback loop that results in radiometric and spectral stabilities to within less than 0.3 percent over a 15-hour period. The airborne imaging spectrometer systems developed at the Jet Propulsion Laboratory incorporate OBC sources to provide auxiliary in-use system calibration data. The use of the OBC source will provide a significant increase in the quantitative accuracy, reliability, and resulting utility of the spectral data collected from current and future imaging spectrometer instruments.

  19. Neutron calibration sources in the Daya Bay experiment

    DOE PAGES

    Liu, J.; Carr, R.; Dwyer, D. A.; ...

    2015-07-09

    We describe the design and construction of the low rate neutron calibration sources used in the Daya Bay Reactor Anti-neutrino Experiment. Such sources are free of correlated gamma-neutron emission, which is essential in minimizing induced background in the anti-neutrino detector. Thus, the design characteristics have been validated in the Daya Bay anti-neutrino detector.

  20. A dynamic pressure source for the calibration of pressure transducers

    NASA Technical Reports Server (NTRS)

    Vezzetti, C. F.; Hilten, J. S.; Mayo-Wells, J. F.; Lederer, P. S.

    1976-01-01

    A dynamic pressure source is described for producing sinusoidally varying pressures of up to 34 kPa zero to peak, over the frequency range of approximately 50 Hz to 2 kHz. The source is intended for the dynamic calibration of pressure transducers. The transducer to be calibrated is mounted near the base of the thick walled aluminum tube forming the vessel so that the pressure sensitive element is in contact with the liquid in the tube. A section of the tube is filled with small steel balls to damp the motion of the 10-St dimethyl siloxane working fluid in order to extend the useful frquency range to higher frequencies than would be provided by an undamped system. The dynamic response of six transducers provided by the sponsor was evaluated using the pressure sources; the results of these calibrations are given.

  1. Design, manufacture, and calibration of infrared radiometric blackbody sources

    SciTech Connect

    Byrd, D.A.; Michaud, F.D.; Bender, S.C.

    1996-04-01

    A Radiometric Calibration Station (RCS) is being assembled at the Los Alamos National Laboratories (LANL) which will allow for calibration of sensors with detector arrays having spectral capability from about 0.4-15 {mu}m. The configuration of the LANL RCS. Two blackbody sources have been designed to cover the spectral range from about 3-15 {mu}m, operating at temperatures ranging from about 180-350 K within a vacuum environment. The sources are designed to present a uniform spectral radiance over a large area to the sensor unit under test. The thermal uniformity requirement of the blackbody cavities has been one of the key factors of the design, requiring less than 50 mK variation over the entire blackbody surface to attain effective emissivity values of about 0.999. Once the two units are built and verified to the level of about 100 mK at LANL, they will be sent to the National Institute of Standards and Technology (NIST), where at least a factor of two improvement will be calibrated into the blackbody control system. The physical size of these assemblies will require modifications of the existing NIST Low Background Infrared (LBIR) Facility. LANL has constructed a bolt-on addition to the LBIR facility that will allow calibration of our large aperture sources. Methodology for attaining the two blackbody sources at calibrated levels of performance equivalent to present state of the art will be explained in the following.

  2. Active radiometric calorimeter for absolute calibration of radioactive sources

    SciTech Connect

    Stump, K.E.; DeWerd, L.A.; Rudman, D.A.; Schima, S.A.

    2005-03-01

    This report describes the design and initial noise floor measurements of a radiometric calorimeter designed to measure therapeutic medical radioactive sources. The instrument demonstrates a noise floor of approximately 2 nW. This low noise floor is achieved by using high temperature superconducting (HTS) transition edge sensor (TES) thermometers in a temperature-control feedback loop. This feedback loop will be used to provide absolute source calibrations based upon the electrical substitution method. Other unique features of the calorimeter are (a) its ability to change sources for calibration without disrupting the vacuum of the instrument, and (b) the ability to measure the emitted power of a source in addition to the total contained source power.

  3. Absolute calorimetric calibration of low energy brachytherapy sources

    NASA Astrophysics Data System (ADS)

    Stump, Kurt E.

    In the past decade there has been a dramatic increase in the use of permanent radioactive source implants in the treatment of prostate cancer. A small radioactive source encapsulated in a titanium shell is used in this type of treatment. The radioisotopes used are generally 125I or 103Pd. Both of these isotopes have relatively short half-lives, 59.4 days and 16.99 days, respectively, and have low-energy emissions and a low dose rate. These factors make these sources well suited for this application, but the calibration of these sources poses significant metrological challenges. The current standard calibration technique involves the measurement of ionization in air to determine the source air-kerma strength. While this has proved to be an improvement over previous techniques, the method has been shown to be metrologically impure and may not be the ideal means of calbrating these sources. Calorimetric methods have long been viewed to be the most fundamental means of determining source strength for a radiation source. This is because calorimetry provides a direct measurement of source energy. However, due to the low energy and low power of the sources described above, current calorimetric methods are inadequate. This thesis presents work oriented toward developing novel methods to provide direct and absolute measurements of source power for low-energy low dose rate brachytherapy sources. The method is the first use of an actively temperature-controlled radiation absorber using the electrical substitution method to determine total contained source power of these sources. The instrument described operates at cryogenic temperatures. The method employed provides a direct measurement of source power. The work presented here is focused upon building a metrological foundation upon which to establish power-based calibrations of clinical-strength sources. To that end instrument performance has been assessed for these source strengths. The intent is to establish the limits of

  4. 10 CFR 35.432 - Calibration measurements of brachytherapy sources.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Calibration measurements of brachytherapy sources. 35.432 Section 35.432 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Manual Brachytherapy... Association of Physicists in Medicine that are made in accordance with paragraph (a) of this section. (c)...

  5. 10 CFR 35.432 - Calibration measurements of brachytherapy sources.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Calibration measurements of brachytherapy sources. 35.432 Section 35.432 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Manual Brachytherapy... Association of Physicists in Medicine that are made in accordance with paragraph (a) of this section. (c)...

  6. 10 CFR 35.432 - Calibration measurements of brachytherapy sources.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Calibration measurements of brachytherapy sources. 35.432 Section 35.432 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Manual Brachytherapy... Association of Physicists in Medicine that are made in accordance with paragraph (a) of this section. (c)...

  7. 10 CFR 35.432 - Calibration measurements of brachytherapy sources.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Calibration measurements of brachytherapy sources. 35.432 Section 35.432 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Manual Brachytherapy... Association of Physicists in Medicine that are made in accordance with paragraph (a) of this section. (c)...

  8. 10 CFR 35.432 - Calibration measurements of brachytherapy sources.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Calibration measurements of brachytherapy sources. 35.432 Section 35.432 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Manual Brachytherapy... Association of Physicists in Medicine that are made in accordance with paragraph (a) of this section. (c)...

  9. Comparison of Blackbody Sources for Low-Temperature IR Calibration

    NASA Astrophysics Data System (ADS)

    Ljungblad, S.; Holmsten, M.; Josefson, L. E.; Klason, P.

    2015-12-01

    Radiation thermometers are traditionally mostly used in high-temperature applications. They are, however, becoming more common in different applications at room temperature or below, in applications such as monitoring frozen food and evaluating heat leakage in buildings. To measure temperature accurately with a pyrometer, calibration is essential. A problem with traditional, commercially available, blackbody sources is that ice is often formed on the surface when measuring temperatures below 0°C. This is due to the humidity of the surrounding air and, as ice does not have the same emissivity as the blackbody source, it biases the measurements. An alternative to a traditional blackbody source has been tested by SP Technical Research Institute of Sweden. The objective is to find a cost-efficient method of calibrating pyrometers by comparison at the level of accuracy required for the intended use. A disc-shaped blackbody with a surface pyramid pattern is placed in a climatic chamber with an opening for field of view of the pyrometer. The temperature of the climatic chamber is measured with two platinum resistance thermometers in the air in the vicinity of the disc. As a rule, frost will form only if the deposition surface is colder than the surrounding air, and, as this is not the case when the air of the climatic chamber is cooled, there should be no frost or ice formed on the blackbody surface. To test the disc-shaped blackbody source, a blackbody cavity immersed in a conventional stirred liquid bath was used as a reference blackbody source. Two different pyrometers were calibrated by comparison using the two different blackbody sources, and the results were compared. The results of the measurements show that the disc works as intended and is suitable as a blackbody radiation source.

  10. Multi-source self-calibration: Unveiling the microJy population of compact radio sources

    NASA Astrophysics Data System (ADS)

    Radcliffe, J. F.; Garrett, M. A.; Beswick, R. J.; Muxlow, T. W. B.; Barthel, P. D.; Deller, A. T.; Middelberg, E.

    2016-03-01

    Context. Very long baseline interferometry (VLBI) data are extremely sensitive to the phase stability of the VLBI array. This is especially important when we reach μJy rms sensitivities. Calibration using standard phase-referencing techniques is often used to improve the phase stability of VLBI data, but the results are often not optimal. This is evident in blank fields that do not have in-beam calibrators. Aims: We present a calibration algorithm termed multi-source self-calibration (MSSC) which can be used after standard phase referencing on wide-field VLBI observations. This is tested on a 1.6 GHz wide-field VLBI data set of the Hubble Deep Field North and the Hubble Flanking Fields. Methods: MSSC uses multiple target sources that are detected in the field via standard phase referencing techniques and modifies the visibilities so that each data set approximates to a point source. These are combined to increase the signal to noise and permit self-calibration. In principle, this should allow residual phase changes caused by the troposphere and ionosphere to be corrected. By means of faceting, the technique can also be used for direction-dependent calibration. Results: Phase corrections, derived using MSSC, were applied to a wide-field VLBI data set of the HDF-N, which comprises of 699 phase centres. MSSC was found to perform considerably better than standard phase referencing and single source self-calibration. All detected sources exhibited dramatic improvements in dynamic range. Using MSSC, one source reached the detection threshold, taking the total detected sources to twenty. This means 60% of these sources can now be imaged with uniform weighting, compared to just 45% with standard phase referencing. In principle, this technique can be applied to any future VLBI observations. The Parseltongue code, which implements MSSC, has been released and made publicly available to the astronomical community (http://https://github.com/jradcliffe5/multi_self_cal).

  11. A Penning discharge source for extreme ultraviolet calibration

    NASA Technical Reports Server (NTRS)

    Finley, David S.; Jelinsky, Patrick; Bowyer, Stuart; Malina, Roger F.

    1986-01-01

    A Penning discharge lamp for use in the calibration of instruments and components for the extreme ultraviolet has been developed. This source is sufficiently light and compact to make it suitable for mounting on the movable slit assembly of a grazing incidence Rowland circle monochromator. Because this is a continuous discharge source, it is suitable for use with photon counting detectors. Line radiation is provided both by the gas and by atoms sputtered off the interchangeable metal cathodes. Usable lines are produced by species as highly ionized as Ne IV and Al V. The wavelength coverage provided is such that a good density of emission lines is available down to wavelengths as short as 100A. This source fills the gap between 100 and 300A, which is inadequately covered by the other available compact continuous radiation sources.

  12. Primary calibration of coiled {sup 103}Pd brachytherapy sources

    SciTech Connect

    Paxton, Adam B.; Culberson, Wesley S.; DeWerd, Larry A.; Micka, John A.

    2008-01-15

    Coiled {sup 103}Pd brachytherapy sources have been developed by RadioMed Corporation for use as low-dose-rate (LDR) interstitial implants. The coiled sources are provided in integer lengths from 1 to 6 cm and address many common issues seen with traditional LDR brachytherapy sources. The current standard for determining the air-kerma strength (S{sub K}) of low-energy LDR brachytherapy sources is the National Institute of Standards and Technology's Wide-Angle Free-Air Chamber (NIST WAFAC). Due to geometric limitations, however, the NIST WAFAC is unable to determine the S{sub K} of sources longer than 1 cm. This project utilized the University of Wisconsin's Variable-Aperture Free-Air Chamber (UW VAFAC) to determine the S{sub K} of the longer coiled sources. The UW VAFAC has shown agreement in S{sub K} values of 1 cm length coils to within 1% of those determined with the NIST WAFAC, but the UW VAFAC does not share the same geometric limitations as the NIST WAFAC. A new source holder was constructed to hold the coiled sources in place during measurements with the UW VAFAC. Correction factors for the increased length of the sources have been determined and applied to the measurements. Using the new source holder and corrections, the S{sub K} of 3 and 6 cm coiled sources has been determined. Corrected UW VAFAC data and ionization current measurements from well chambers have been used to determine calibration coefficients for use in the measurement of 3 and 6 cm coiled sources in well chambers. Thus, the UW VAFAC has provided the first transferable, primary measurement of low-energy LDR brachytherapy sources with lengths greater than 1 cm.

  13. Calibration of R/V Marcus G. Langseth Seismic Sources

    NASA Astrophysics Data System (ADS)

    Diebold, J.; Tolstoy, M.; Webb, S.; Doermann, L.; Bohenstihl, D.; Nooner, S.; Crone, T.; Holmes, R. C.

    2008-12-01

    NSF-owned Research Vessel Marcus G. Langseth is operated by Lamont-Doherty Earth Observatory, providing the tools for full-scale marine seismic surveys to the academic community. Since inauguration of science operations, Langseth has successfully supported 2D and 3D seismic operations, including offshore- onshore and OBS refraction profiling A significant component of Langseths equipage is the seismic source, comprising four identical linear subarrays which can be combined in a number of configurations according to the needs of each scientific mission. To ensure a full understanding of the acoustic levels of these sources and in order to mitigate their possible impact upon marine life through accurate determination of safety radii, an extensive program of acoustic calibration was carried out in 2007 and 2008, during Langseths shakedown exercises. A total of 14000+ airgun array discharges were recorded in three separate locations with water depths varying from 1750 to 45 meters and at source-receiver offsets between near-zero and 17 km. The quantity of data recorded allows significant quantitative analysis of the sound levels produced by the Langseth seismic sources. A variety of acoustic metrics will be presented and compared, including peak levels and energy-based measures such as RMS, Energy Flux Density and its equivalent, Sound Exposure Level. It is clearly seen that water depth exerts a fundamental control on received sound levels, but also that these effects can be predicted with reasonable accuracy.

  14. Aqueous blackbody calibration source for millimeter-wave/terahertz metrology

    SciTech Connect

    Dietlein, Charles; Popovic, Zoya; Grossman, Erich N

    2008-10-20

    This paper describes a calibrated broadband emitter for the millimeter-wave through terahertz frequency regime, called the aqueous blackbody calibration source. Due to its extremely high absorption, liquid water is chosen as the emitter on the basis of reciprocity. The water is constrained to a specific shape (an optical trap geometry) in an expanded polystyrene (EPS) container and maintained at a selected, uniform temperature. Uncertainty in the selected radiometric temperature due to the undesirable reflectance present at a water interface is minimized by the trap geometry, ensuring that radiation incident on the entrance aperture encounters a pair of s and a pair of p reflections at 45 deg. . For water reflectance Rw of 40% at 45 deg. in W-band, this implies a theoretical effective aperture emissivity of (1-R{sup 2}wsR{sup 2}wp)>98.8%. From W-band to 450 GHz, the maximum radiometric temperature uncertainty is {+-}0.40 K, independent of water temperature. Uncertainty from 450 GHz to 1 THz is increased due to EPS scattering and absorption, resulting in a maximum uncertainty of -3 K at 1 THz.

  15. R/V EWING seismic source array calibrations: 2003

    NASA Astrophysics Data System (ADS)

    Diebold, J.; Webb, S.; Tolstoy, M.; Rawson, M.; Holmes, C.; Bohnenstiehl, D.; Chapp, E.

    2003-12-01

    In the Northern Gulf of Mexico, May, 2003, an NSF-funded effort was carried out to obtain calibrated measurements of the various airgun arrays deployed by R/V EWING during its seismic surveys. The motivations for this were several: to ground-truth the modeling upon which safety radii for marine mammal mitigation are established; to obtain broadband digitized signals which will accurately define the full spectral content of airgun signatures; to investigate the effects of seafloor interactions and their contribution to the acoustic noise levels from seismic sources. For this purpose, a digital, remotely telemetering spar buoy was designed and assembled; affording interactive control over the choice of two hydrophone channels, four fixed gain settings and four digitizing rates [6,250 - 50,000 Hz.] Three deployments were planned: a deep-water site, suitable for comparison of actual signals with modeled results; a shallow-water [25 - 50m] site where the effects of bottom interaction would be strongest; and a continental-slope site, which represents the favored habitat of many cetacean species. Methodology was developed which enabled the sequential discharge of four subarrays of 6, 10, 12 and 20 airguns. A separate run was made with two "GI" airguns, the favored high resolution survey source. An Incidental Harassment Authorization and a Biological Opinion, including an Incidental Take Statement were issued for the project by National Marine Fisheries, and a suite of marine mammal observation and mitigation procedures was followed. The deep and shallow water sites were occupied, and some 440 airgun signals were recorded. The slope site work was cancelled due to weather too poor for accurate marine mammal observation, but calibration was subsequently carried out with an exploration industry source vessel in a similar environment. Preliminary results indicate that the mitigation modeling is accurate, though somewhat conservative; that the radiated energy from airgun arrays

  16. 10 CFR 35.2432 - Records of calibration measurements of brachytherapy sources.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Records of calibration measurements of brachytherapy sources. 35.2432 Section 35.2432 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL... manufacturer's name, model number, and serial number for the source and the instruments used to calibrate...

  17. 10 CFR 35.2432 - Records of calibration measurements of brachytherapy sources.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Records of calibration measurements of brachytherapy sources. 35.2432 Section 35.2432 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL... last use of the source. (b) The record must include— (1) The date of the calibration; (2)...

  18. 10 CFR 70.19 - General license for calibration or reference sources.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... section, plutonium in the form of calibration or reference sources: (1) Any person in a non-agreement... plutonium in such sources; (2) Shall not receive, possess, use or transfer such source unless the source, or... regulatory authority. Do not remove this label. caution—radioactive material—this source contains...

  19. 10 CFR 70.19 - General license for calibration or reference sources.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... section, plutonium in the form of calibration or reference sources: (1) Any person in a non-agreement... plutonium in such sources; (2) Shall not receive, possess, use or transfer such source unless the source, or... regulatory authority. Do not remove this label. caution—radioactive material—this source contains...

  20. 10 CFR 70.19 - General license for calibration or reference sources.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... section, plutonium in the form of calibration or reference sources: (1) Any person in a non-agreement... plutonium in such sources; (2) Shall not receive, possess, use or transfer such source unless the source, or... regulatory authority. Do not remove this label. caution—radioactive material—this source contains...

  1. 10 CFR 70.19 - General license for calibration or reference sources.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... section, plutonium in the form of calibration or reference sources: (1) Any person in a non-agreement... plutonium in such sources; (2) Shall not receive, possess, use or transfer such source unless the source, or... regulatory authority. Do not remove this label. caution—radioactive material—this source contains...

  2. 10 CFR 70.19 - General license for calibration or reference sources.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... section, plutonium in the form of calibration or reference sources: (1) Any person in a non-agreement... plutonium in such sources; (2) Shall not receive, possess, use or transfer such source unless the source, or... regulatory authority. Do not remove this label. caution—radioactive material—this source contains...

  3. Phased Array Radiometer Calibration Using a Radiated Noise Source

    NASA Technical Reports Server (NTRS)

    Srinivasan, Karthik; Limaye, Ashutoch S.; Laymon, Charles A.; Meyer, Paul J.

    2010-01-01

    Electronic beam steering capability of phased array antenna systems offer significant advantages when used in real aperture imaging radiometers. The sensitivity of such systems is limited by the ability to accurately calibrate variations in the antenna circuit characteristics. Passive antenna systems, which require mechanical rotation to scan the beam, have stable characteristics and the noise figure of the antenna can be characterized with knowledge of its physical temperature [1],[2]. Phased array antenna systems provide the ability to electronically steer the beam in any desired direction. Such antennas make use of active components (amplifiers, phase shifters) to provide electronic scanning capability while maintaining a low antenna noise figure. The gain fluctuations in the active components can be significant, resulting in substantial calibration difficulties [3]. In this paper, we introduce two novel calibration techniques that provide an end-to-end calibration of a real-aperture, phased array radiometer system. Empirical data will be shown to illustrate the performance of both methods.

  4. A database of phase calibration sources and their radio spectra for the Giant Metrewave Radio Telescope

    NASA Astrophysics Data System (ADS)

    Lal, Dharam V.; Dubal, Shilpa S.; Sherkar, Sachin S.

    2016-12-01

    We are pursuing a project to build a database of phase calibration sources suitable for Giant Metrewave Radio Telescope (GMRT). Here we present the first release of 45 low frequency calibration sources at 235 MHz and 610 MHz. These calibration sources are broadly divided into quasars, radio galaxies and unidentified sources. We provide their flux densities, models for calibration sources, ( u, v) plots, final deconvolved restored maps and clean-component lists/files for use in the Astronomical Image Processing System ( aips) and the Common Astronomy Software Applications ( casa). We also assign a quality factor to each of the calibration sources. These data products are made available online through the GMRT observatory website. In addition we find that (i) these 45 low frequency calibration sources are uniformly distributed in the sky and future efforts to increase the size of the database should populate the sky further, (ii) spectra of these calibration sources are about equally divided between straight, curved and complex shapes, (iii) quasars tend to exhibit flatter radio spectra as compared to the radio galaxies or the unidentified sources, (iv) quasars are also known to be radio variable and hence possibly show complex spectra more frequently, and (v) radio galaxies tend to have steeper spectra, which are possibly due to the large redshifts of distant galaxies causing the shift of spectrum to lower frequencies.

  5. Source-based calibration of space instruments using calculable synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Klein, Roman; Fliegauf, Rolf; Kroth, Simone; Paustian, Wolfgang; Reichel, Thomas; Richter, Mathias; Thornagel, Reiner

    2016-10-01

    Physikalisch-Technische Bundesanstalt (PTB) has more than 20 years of experience in the calibration of space-based instruments using synchrotron radiation to cover the ultraviolet (UV), vacuum UV (VUV), and x-ray spectral range. Over the past decades, PTB has performed calibrations for numerous space missions within scientific collaborations and has become an important partner for activities in this field. New instrumentation at the electron storage ring, metrology light source, creates additional calibration possibilities within this framework. A new facility for the calibration of radiation transfer source standards with a considerably extended spectral range has been put into operation. The commissioning of a large vacuum vessel that can accommodate entire space instruments opens up new prospects. Finally, an existing VUV transfer calibration source was upgraded to increase the spectral range coverage to a band from 15 to 350 nm.

  6. A Portable Ultra-Stable Calibration Source for Precision RV Measurements in NIR

    NASA Astrophysics Data System (ADS)

    Wang, Ji; Ge, J.; Wan, X.; Delgado, A.; Jakeman, H.

    2011-09-01

    In the next decade, astronomers are aiming at reaching 0.1 m/s RV precision, which will enable discoveries of Earth-like planets around solar-type stars. However, the RV precision is currently limited by stellar activity, the stability and bandwidth of RV calibration sources. We proposed to use an ultra-stable monolithic Michelson interferometer as an RV calibration source. This monolithic interferometer source has several advantages over the conventional RV calibration sources: (1), it produces sinusoidal spectral features which can be easily processed, unlike gas absorption cells or emission lamps, which spectral line distributions are extremely nonuniform; (2), it has a wide spectral coverage from visible to near infrared (NIR); (3), it is designed to be thermal-stable (thermally compensated) so that the thermal induced RV drift is very small; (4), it is also field compensated to ensure a high optical efficiency so that a spatially incoherent continuum light source is suitable for producing bright calibration light (unlike the faint ThAr emission lamp); (5). it is extremely compact ( 10x10x10 cm3) and low cost compared to the bulky (more than 1x1x1 m3) and extremely high cost laser frequency combs. With the help of the proposed RV calibration source, the search of exoplanets around M dwarfs or even L, T dwarfs can be extended to the NIR band. The predicted sub m/s RV calibration precision will enable the discovery of Earth-like planets in the habitable zone around M dwarfs. The proposed calibration source may be quite useful for calibrating future space instruments for possible space RV exoplanet searches in the IR region where RV measurements are free of contamination of the Earth's telluric lines, which is a serious issue for ground-based IR RV observations. We will present our latest results of the calibration source on its application for both Echelle spectrograph and the instrument adopting DFDI method.

  7. Radio Astronomical Polarimetry and Point-Source Calibration

    NASA Astrophysics Data System (ADS)

    van Straten, W.

    2004-05-01

    A mathematical framework is presented for use in the experimental determination of the polarimetric response of observatory instrumentation. Elementary principles of linear algebra are applied to model the full matrix description of the polarization measurement equation by least-squares estimation of nonlinear, scalar parameters. The formalism is applied to calibrate the center element of the Parkes Multibeam receiver using observations of the millisecond pulsar PSR J0437-4715 and the radio galaxy 3C 218 (Hydra A).

  8. Ka-Band Monopulse Antenna Pointing Calibration Using Wideband Radio Sources

    NASA Astrophysics Data System (ADS)

    Buu, C.; Calvo, J.; Cheng, T.-H.; Vazquez, M.

    2010-08-01

    A new method of performing a system end-to-end monopulse antenna calibration using widely available wideband astronomical radio sources is presented as an alternative to the current method of using a spacecraft signal. Current monopulse calibration requires a spacecraft carrier signal to measure amplitude and phase differences in the monopulse feed and low-noise amplifiers (LNAs). The alternative method presented here will allow the ground station to perform monopulse calibrations during maintenance periods instead of spacecraft track time, and provide an end-to-end system check-out capability without requiring a spacecraft signal. In this article, we give an overview of the current calibration approach, describe a new method for calibrating with radio sources, and present results from field testing of this new method.

  9. Feasibility of calibrating elongated brachytherapy sources using a well-type ionization chamber

    SciTech Connect

    Meigooni, Ali S.; Awan, Shahid B.; Dou, Kai

    2006-11-15

    Recently, elongated brachytherapy sources (active length >1 cm) have become commercially available for interstitial prostate implants. These sources were introduced to improve the quality of brachytherapy procedures by eliminating the migration and seed bunching associated with loose seed-type implants. However, the inability to calibrate elongated brachytherapy sources with the Wide-Angle Free-Air Chamber (WAFAC) used by the National Institute of Standards and Technology (NIST) hinders the experimental determination of dosimetric parameters of these source types. In order to resolve this shortcoming, an interim solution has been introduced for calibration of elongated brachytherapy sources using a commercially available well-type ionization chamber. The feasibility of this procedure was examined by calibrating RadioCoil{sup Tm} {sup 103}Pd sources with active lengths ranging from 1 to 7 cm.

  10. On-sky calibration performance of a monolithic Michelson interferometer filtered source

    NASA Astrophysics Data System (ADS)

    Ge, Jian; Ma, Bo; Powell, Scott; Varosi, Frank; Schofield, Sidney; Grieves, Nolan; Liu, Jian

    2014-07-01

    In the new era of searching for Earth-like planets, new generation radial velocity (RV) high resolution spectrographs requires ~0.1 m/s Doppler calibration accuracy in the visible band and a similar calibration precision in the near infrared. The patented stable monolithic Michelson interferometer filtered source called the Sine source emerges as a very promising calibration device. This Sine source has the potential of covering the practical working wavelengths (~0.38- 2.5 μm) for Doppler measurements with high resolution optical and near infrared high resolution spectrographs at the ground-based telescopes. The single frame calibration precision can reach < 0.1 m/s for the state of the art spectrographs, and it can be easily designed to match the intrinsic sensitivities of future Doppler instruments. The Sine source also has the great practical advantages in compact (portable) size and low cost. Here we report early results from on-sky calibration of a Sine source measured with two state-of-the-art TOU optical high resolution spectrograph (R=100,000, 0.38-0.9 microns) and FIRST near infrared spectrograph (R=50,000, 0.8-1.8 microns) at a 2 meter robotic telescope at Fairborn Observatory in Arizona. The results with the TOU spectrograph monitoring over seven days show that the Sine source has produced ~3 times better calibration precision than the ThAr calibration (RMS = 2.7m/s vs. 7.4m/s) at 0.49-0.62 microns where calibration data have been processed by our preliminary data pipeline and ~1.4 times better than the iodine absorption spectra (RMS=3.6 m/s) at the same wavelength region. As both ThAr and Iodine have reached sub m/s calibration accuracy with existing Doppler instruments (such as HARPS and HIRES), it is likely that the sine source would provide similar improvement once a better data pipeline and an upgraded version of a Sine source are developed. It is totally possible to reach ~0.1 m/s in the optical wavelength region. In addition, this Sine source

  11. Photometric Calibration of an EUV Flat Field Spectrometer at the Advanced Light Source

    SciTech Connect

    May, M; Lepson, J; Beiersdorfer, P; Thorn, D; Chen, H; Hey, D; Smith, A

    2002-07-03

    The photometric calibration of ail extreme ultraviolet flat field spectrometer has been done at the Advanced Light Source at LBNL. This spectrometer is used to record spectrum for atomic physics research from highly charged ions in plasmas created in the Livermore electron beam ion traps EBIT-I and SUPEREBIT. Two calibrations were done each with a different gold-coated grating, a 1200 {ell}/mm and a 2400 {ell}/mm, that covered 75-300{angstrom} and 15-160{angstrom}, respectively. The detector for this calibration was a back thinned CCD. The relative calibration was determined for several different incident angles for both gratings. Within the scatter of the data, the calibration was roughly insensitive to the incidence angle for the range of angles investigated.

  12. 10 CFR 31.8 - Americium-241 and radium-226 in the form of calibration or reference sources.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Americium-241 and radium-226 in the form of calibration or... BYPRODUCT MATERIAL § 31.8 Americium-241 and radium-226 in the form of calibration or reference sources. (a..., americium-241 or radium-226 in the form of calibration or reference sources: (1) Any person in a...

  13. 10 CFR 31.8 - Americium-241 and radium-226 in the form of calibration or reference sources.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Americium-241 and radium-226 in the form of calibration or... BYPRODUCT MATERIAL § 31.8 Americium-241 and radium-226 in the form of calibration or reference sources. (a..., americium-241 or radium-226 in the form of calibration or reference sources: (1) Any person in a...

  14. 10 CFR 31.8 - Americium-241 and radium-226 in the form of calibration or reference sources.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Americium-241 and radium-226 in the form of calibration or... BYPRODUCT MATERIAL § 31.8 Americium-241 and radium-226 in the form of calibration or reference sources. (a..., americium-241 or radium-226 in the form of calibration or reference sources: (1) Any person in a...

  15. 10 CFR 31.8 - Americium-241 and radium-226 in the form of calibration or reference sources.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Americium-241 and radium-226 in the form of calibration or... BYPRODUCT MATERIAL § 31.8 Americium-241 and radium-226 in the form of calibration or reference sources. (a..., americium-241 or radium-226 in the form of calibration or reference sources: (1) Any person in a...

  16. 10 CFR 31.8 - Americium-241 and radium-226 in the form of calibration or reference sources.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Americium-241 and radium-226 in the form of calibration or... BYPRODUCT MATERIAL § 31.8 Americium-241 and radium-226 in the form of calibration or reference sources. (a..., americium-241 or radium-226 in the form of calibration or reference sources: (1) Any person in a...

  17. Calibration of time of flight detectors using laser-driven neutron source

    SciTech Connect

    Mirfayzi, S. R.; Kar, S. Ahmed, H.; Green, A.; Alejo, A.; Jung, D.; Krygier, A. G.; Freeman, R. R.; Clarke, R.; Fuchs, J.; Vassura, L.; Kleinschmidt, A.; Roth, M.; Morrison, J. T.; Najmudin, Z.; Nakamura, H.; Norreys, P.; Oliver, M.; Zepf, M.; Borghesi, M.

    2015-07-15

    Calibration of three scintillators (EJ232Q, BC422Q, and EJ410) in a time-of-flight arrangement using a laser drive-neutron source is presented. The three plastic scintillator detectors were calibrated with gamma insensitive bubble detector spectrometers, which were absolutely calibrated over a wide range of neutron energies ranging from sub-MeV to 20 MeV. A typical set of data obtained simultaneously by the detectors is shown, measuring the neutron spectrum emitted from a petawatt laser irradiated thin foil.

  18. Calibration of time of flight detectors using laser-driven neutron source

    NASA Astrophysics Data System (ADS)

    Mirfayzi, S. R.; Kar, S.; Ahmed, H.; Krygier, A. G.; Green, A.; Alejo, A.; Clarke, R.; Freeman, R. R.; Fuchs, J.; Jung, D.; Kleinschmidt, A.; Morrison, J. T.; Najmudin, Z.; Nakamura, H.; Norreys, P.; Oliver, M.; Roth, M.; Vassura, L.; Zepf, M.; Borghesi, M.

    2015-07-01

    Calibration of three scintillators (EJ232Q, BC422Q, and EJ410) in a time-of-flight arrangement using a laser drive-neutron source is presented. The three plastic scintillator detectors were calibrated with gamma insensitive bubble detector spectrometers, which were absolutely calibrated over a wide range of neutron energies ranging from sub-MeV to 20 MeV. A typical set of data obtained simultaneously by the detectors is shown, measuring the neutron spectrum emitted from a petawatt laser irradiated thin foil.

  19. Angular response calibration of the burst and transient source experiment

    NASA Technical Reports Server (NTRS)

    Lestrade, John Patrick

    1988-01-01

    The Gamma Ray Observatory includes four experiments designed to observe the gamma-ray universe. Laboratory measurements to test the response the Burst and Transient Source Experiment (BATSE) modules to gamma-ray sources that are non-axial were recently completed. The results of these observations are necessary for the correct interpretation of BATSE data obtained after it is put in Earth orbit. The launch is planned for March, 1900. Preliminary analyses of these test data show the presence of a radial dependence to the detector's light collection efficiency. It is proposed to evaluate the importance of this radial response, analyze future experimental data to derive the actual functional dependence on radius, and calculate the net effect on the output spectrum as a function of the angle of incidence.

  20. Augmenting watershed model calibration with incorporation of ancillary data sources and qualitative soft data sources

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Watershed simulation models can be calibrated using “hard data” such as temporal streamflow observations; however, users may find upon examination of detailed outputs that some of the calibrated models may not reflect summative actual watershed behavior. Thus, it is necessary to use “soft data” (i....

  1. Results from the intercalibration of optical low-light calibration sources 2011

    NASA Astrophysics Data System (ADS)

    Brändström, B. U. E.; Enell, C.-F.; Widell, O.; Hansson, T.; Whiter, D.; Mäkinen, S.; Mikhaylova, D.; Axelsson, K.; Sigernes, F.; Gulbrandsen, N.; Schlatter, N. M.; Gjendem, A. G.; Cai, L.; Reistad, J. P.; Daae, M.; Demissie, T. D.; Andalsvik, Y. L.; Roberts, O.; Poluyanov, S.; Chernouss, S.

    2011-12-01

    Following the 38th Annual Meeting on Atmospheric studies by Optical methods at Siuntio in Finland, an intercalibration workshop for optical low-light calibration sources was held in Sodankylä, Finland. The main purpose of this workshop was to provide a comparable scale for absolute measurements of aurora and airglow. All sources brought to the intercalibration workshop were compared to an international standard source (Fritz-Peak) using the Lindau Calibration Photometer built by Wilhelm Barke and Hans Lauche in 1984. The international standard source is on loan from Michael Gadsden, Aberdeen. The results were compared to several earlier intercalibration workshops. It was found that most sources were fairly stable over time with errors in the range of 5-20%. To further validate the results, two sources were also intercalibrated at UNIS, Longyearbyen, Svalbard. Preliminary analysis indicate good agreement with the intercalibration in Sodankylä.

  2. A Volt Second Source for Calibration of Integrator in a Pulsed Field Magnetometer

    NASA Astrophysics Data System (ADS)

    Lin, An-Li; He, Jian; Zhang, Yue; John, Dudding; Michael, Hall

    2007-11-01

    A volt-second (Vs) source intended for absolutely calibrating the integrator in a pulsed field magnetometer (PFM) is designed and proven to be with accurate rising and falling edges and reasonable lower uncertainty. A comparison experiment shows that the difference between the magnetic fluxes generated respectively by the Vs source and the mutual inductor is within ±0.04%. The PFM is then calibrated in an absolute way of the Vs source. The calibrated PFM gives the measured results in good agreement with a static BH tracer supplied by National Institute of Metrology of China and provides a convenient way of studying the effect of mathematic process on the dynamic measuring curve of PFMs.

  3. Wideband spherically focused PVDF acoustic sources for calibration of ultrasound hydrophone probes.

    PubMed

    Selfridge, A; Lewin, P A

    2000-01-01

    Several broadband sources have been developed for the purpose of calibrating hydrophones. The specific configuration described is intended for the calibration of hydrophones In a frequency range of 1 to 40 MHz. All devices used 25 /spl mu/m film of PVDF bonded to a matched backing. Two had radii of curvatures (ROC) of 25.4 and 127 mm with f numbers of 3.8 and 19, respectively. Their active element diameter was 0.28 in (6.60 mm). The active diameter of the third source used was 25 mm, and it had an ROC of 254 mm and an f number of 10. The use of a focused element minimized frequency-dependent diffraction effects, resulting in a smooth variation of acoustic pressure at the focus from 1 to 40 MHz. Also, using a focused PVDF source permitted calibrations above 20 MHz without resorting to harmonic generation via nonlinear propagation.

  4. Point-source calibration of a segmented gamma-ray scanner

    SciTech Connect

    Sheppard, G.A.; Piquette, E.C.

    1994-08-01

    For a conventional segmented gamma-ray scanner (SGS) in which the sample is rotated continuously within a fixed detector field of view, the data will not support alternatives to the assumption that the gamma-emitting nuclides and the matrix in which they reside are uniformly distributed. This homogeneity assumption permits the geometry of samples and calibration standards to be approximated by that of a non attenuating line source on the axis of rotation. Other common SGS assumptions are that the detector is perfectly collimated, that its response is flat over its field of view, and that it can be approximated adequately by a line. All of these assumption have led to a preference for homogeneous calibration standards. Preparation and certification of such calibration standards are usually difficult and expensive. Storage and transportation of SGS standards can be inconvenient or even quite troublesome. The authors have proposed and tested an alternative method of SGS calibration that only requires a point-source standard. The proposed technique relies on the empirical determination of a normalized two-dimensional detector response and the measurement of the count rate from a point-source standard located at the response apex. With these data, the system`s response to a distributed, homogeneous samples can be predicted using numerical integration. Typical biases measured using a commercially available SGS calibrated with a point source have been less than 2%.

  5. Results from the intercalibration of optical low light calibration sources 2011

    NASA Astrophysics Data System (ADS)

    Brändström, B. U. E.; Enell, C.-F.; Widell, O.; Hansson, T.; Whiter, D.; Mäkinen, S.; Mikhaylova, D.; Axelsson, K.; Sigernes, F.; Gulbrandsen, N.; Schlatter, N. M.; Gjendem, A. G.; Cai, L.; Reistad, J. P.; Daae, M.; Demissie, T. D.; Andalsvik, Y. L.; Roberts, O.; Poluyanov, S.; Chernouss, S.

    2012-05-01

    Following the 38th Annual European Meeting on Atmospheric Studies by Optical Methods in Siuntio in Finland, an intercalibration workshop for optical low light calibration sources was held in Sodankylä, Finland. The main purpose of this workshop was to provide a comparable scale for absolute measurements of aurora and airglow. All sources brought to the intercalibration workshop were compared to the Fritz Peak reference source using the Lindau Calibration Photometer built by Wilhelm Barke and Hans Lauche in 1984. The results were compared to several earlier intercalibration workshops. It was found that most sources were fairly stable over time, with errors in the range of 5-25%. To further validate the results, two sources were also intercalibrated at UNIS, Longyearbyen, Svalbard. Preliminary analysis indicates agreement with the intercalibration in Sodankylä within about 15-25%.

  6. Spectral phase-based automatic calibration scheme for swept source-based optical coherence tomography systems

    NASA Astrophysics Data System (ADS)

    Ratheesh, K. M.; Seah, L. K.; Murukeshan, V. M.

    2016-11-01

    The automatic calibration in Fourier-domain optical coherence tomography (FD-OCT) systems allows for high resolution imaging with precise depth ranging functionality in many complex imaging scenarios, such as microsurgery. However, the accuracy and speed of the existing automatic schemes are limited due to the functional approximations and iterative operations used in their procedures. In this paper, we present a new real-time automatic calibration scheme for swept source-based optical coherence tomography (SS-OCT) systems. The proposed automatic calibration can be performed during scanning operation and does not require an auxiliary interferometer for calibration signal generation and an additional channel for its acquisition. The proposed method makes use of the spectral component corresponding to the sample surface reflection as the calibration signal. The spectral phase function representing the non-linear sweeping characteristic of the frequency-swept laser source is determined from the calibration signal. The phase linearization with improved accuracy is achieved by normalization and rescaling of the obtained phase function. The fractional-time indices corresponding to the equidistantly spaced phase intervals are estimated directly from the resampling function and are used to resample the OCT signals. The proposed approach allows for precise calibration irrespective of the path length variation induced by the non-planar topography of the sample or galvo scanning. The conceived idea was illustrated using an in-house-developed SS-OCT system by considering the specular reflection from a mirror and other test samples. It was shown that the proposed method provides high-performance calibration in terms of axial resolution and sensitivity without increasing computational and hardware complexity.

  7. Fast calibration of SPECT monolithic scintillation detectors using un-collimated sources

    NASA Astrophysics Data System (ADS)

    España, Samuel; Deprez, Karel; Van Holen, Roel; Vandenberghe, Stefaan

    2013-07-01

    Monolithic scintillation detectors for positron emission tomography and single-photon emission computed tomography (SPECT) imaging have many advantages over pixelated detectors. The use of monolithic crystals allows for reducing the scintillator cost per unit volume and increasing the sensitivity along with the energy and timing resolution of the detector. In addition, on thick detectors the depth-of-interaction can be determined without additional hardware. However, costly and complex calibration procedures have been proposed to achieve optimal detector performance for monolithic detectors. This hampers their use in commercial systems. There is thus, a need for simple calibration routines that can be performed on assembled systems. The main goal of this work is to develop a simplified calibration procedure based on acquired training data. In comparison with other methods that use training data acquired with beam sources attached to robotic stages, the proposed method uses a static un-collimated activity source with simple geometry acquiring in a reasonable time. Once the data are acquired, the calibration of the detector is accomplished in three steps: energy calibration based on the k-means clustering method, self-organization based on the self-organizing maps algorithm, and distortion correction based on the Monge-Kantorovich grid adaptation. The proposed calibration method was validated for 2D positioning using a SPECT detector. Similar results were obtained by comparison with an existing calibration method (maximum likelihood estimation). In conclusion, we proposed a novel calibration method for monolithic scintillation detectors that greatly simplifies their use with optimal performance in SPECT systems.

  8. Suppression of fiber modal noise induced radial velocity errors for bright emission-line calibration sources

    SciTech Connect

    Mahadevan, Suvrath; Halverson, Samuel; Ramsey, Lawrence; Venditti, Nick

    2014-05-01

    Modal noise in optical fibers imposes limits on the signal-to-noise ratio (S/N) and velocity precision achievable with the next generation of astronomical spectrographs. This is an increasingly pressing problem for precision radial velocity spectrographs in the near-infrared (NIR) and optical that require both high stability of the observed line profiles and high S/N. Many of these spectrographs plan to use highly coherent emission-line calibration sources like laser frequency combs and Fabry-Perot etalons to achieve precision sufficient to detect terrestrial-mass planets. These high-precision calibration sources often use single-mode fibers or highly coherent sources. Coupling light from single-mode fibers to multi-mode fibers leads to only a very low number of modes being excited, thereby exacerbating the modal noise measured by the spectrograph. We present a commercial off-the-shelf solution that significantly mitigates modal noise at all optical and NIR wavelengths, and which can be applied to spectrograph calibration systems. Our solution uses an integrating sphere in conjunction with a diffuser that is moved rapidly using electrostrictive polymers, and is generally superior to most tested forms of mechanical fiber agitation. We demonstrate a high level of modal noise reduction with a narrow bandwidth 1550 nm laser. Our relatively inexpensive solution immediately enables spectrographs to take advantage of the innate precision of bright state-of-the art calibration sources by removing a major source of systematic noise.

  9. Design of spectrally tunable calibration source based on Digital Micromirror Device (DMD)

    NASA Astrophysics Data System (ADS)

    Zhai, Wenchao; Zhang, Meng; Meng, Fangang; Zheng, Xiaobing

    2016-10-01

    A kind of novel calibration source with dual output modes, namely, narrow-band and broadband, was designed. The optical system of the source is refractive, in spectrometer-like optical configurations using a prism as the dispersion device. The Digital Micromirror Device (DMD) is used as the spatial light modulator, which locates at the focal plane of the dispersion unit. The dispersive wavelengths are located at the active area of DMD, every column of the DMD corresponds to a different wavelength and the rows of each DMD column correspond to the intensity of that wavelength. With the modulation of the DMD, it can produce narrow-band/monochromatic output like a monochromator by switching the corresponding columns on, and broadband output by switching several different columns on. The source's operating band spans 450 2250nm, consisting of two independent parts which span 450 1000nm and 1000 2250nm, respectively. The narrow-band bandwidths spans 5 28nm for VIS-NIR and 20 40nm for SWIR subsystems. Several broadband target spectra, including sea water, plants and sun, were simulated by this source through spectral simulation algorithm. The source's radiometric metrics are suitable to be traced to the absolute cryogenic radiometer (ACR), the most accurate optical power standard at present, which is helpful to improve the calibration accuracy for remote sensors at the beginning. The capability of simulating target spectra will reduce the calibration uncertainties caused by the spectral mismatch between calibration sources and targets viewed by the remote sensors. Based on the considerations above, the source is very appropriate and applicable for remote sensor's calibration.

  10. Crowd-Sourced Calibration: The GEDI Strategy for Empirical Biomass Estimation Using Spaceborne Lidar

    NASA Astrophysics Data System (ADS)

    Dubayah, R.

    2015-12-01

    The central task in estimating forest biomass from spaceborne sensors is the development of calibration equations that relate observed forest structure to biomass at a variety of spatial scales. Empirical methods generally rely on statistical estimation or machine learning techniques where field-based estimates of biomass at the plot level are associated with post-launch observations of variables such as canopy height and cover. For global-scale mapping the process is complex and leads to a number of questions: How many calibrations are required to capture non-stationarity in the relationships? Where does one calibration begin and another end? Should calibrations be conditioned by biome? Vegetation type? Land-use? Post-launch calibrations lead to further complications, such as the requirement to have sufficient field plot data underneath potentially sparse satellite observations, spatial and temporal mismatches in scale between field plots and pixels, and geolocation uncertainty, both in the plots and the satellite data. The Global Ecosystem Dynamics Investigation (GEDI) is under development by NASA to estimate forest biomass. GEDI will deploy a multi-beam lidar on the International Space Station and provide billions of observations of forest structure per year. Because GEDI uses relatively small footprints, about 25 m diameter, post-launch calibration is exceptionally problematic for the reasons listed earlier. Instead, GEDI will use a kind of "crowd-sourced" calibration strategy where existing lidar observations and the corresponding plot biomass will be assembled from data contributed by the science community. Through a process of continuous updating, calibrations will be refined as more data is ingested. This talk will focus on the GEDI pre-launch calibration strategy and present initial progress on its development, and how it forms the basis for meeting mission biomass requirements.

  11. 10 CFR 35.65 - Authorization for calibration, transmission, and reference sources.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Authorization for calibration, transmission, and reference sources. 35.65 Section 35.65 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL.... Any person authorized by § 35.11 for medical use of byproduct material may receive, possess, and...

  12. 10 CFR 35.65 - Authorization for calibration, transmission, and reference sources.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Authorization for calibration, transmission, and reference sources. 35.65 Section 35.65 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL.... Any person authorized by § 35.11 for medical use of byproduct material may receive, possess, and...

  13. 10 CFR 35.65 - Authorization for calibration, transmission, and reference sources.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Authorization for calibration, transmission, and reference sources. 35.65 Section 35.65 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL.... Any person authorized by § 35.11 for medical use of byproduct material may receive, possess, and...

  14. 10 CFR 35.65 - Authorization for calibration, transmission, and reference sources.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Authorization for calibration, transmission, and reference sources. 35.65 Section 35.65 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL.... Any person authorized by § 35.11 for medical use of byproduct material may receive, possess, and...

  15. 10 CFR 35.65 - Authorization for calibration, transmission, and reference sources.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Authorization for calibration, transmission, and reference sources. 35.65 Section 35.65 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL.... Any person authorized by § 35.11 for medical use of byproduct material may receive, possess, and...

  16. THE SUN AS A CALIBRATION SIGNAL SOURCE FOR L- AND S-BAND TELEMETRY

    DTIC Science & Technology

    performance at all times. The sun provides sufficient signal strength in these bands, and its subtended angle of 0.5 deg from the earth is small enough to...communications link the sun could be used as a signal source for calibration purposes. Characteristics of solar emission are reviewed briefly, and the methods of determining receiving system noise temperature are developed.

  17. LED based powerful nanosecond light sources for calibration systems of deep underwater neutrino telescopes

    NASA Astrophysics Data System (ADS)

    Lubsandorzhiev, B. K.; Poleshuk, R. V.; Shaibonov, B. A. J.; Vyatchin, Y. E.

    2009-04-01

    Powerful nanosecond light sources based on LEDs have been developed for use in calibration systems of deep underwater neutrino telescopes. The light sources use either matrixes of ultra bright blue InGaN LEDs or new generation high power blue LEDs. It is shown that such light sources have light yield of up to 1010-1012 photons per pulse with very fast light emission kinetics. The developed light sources are currently used in a number of astroparticle physics experiments, namely: the lake Baikal neutrino experiment, the TUNKA EAS experiment, etc.

  18. Sources and assumptions for the vicarious calibration of ocean color satellite observations

    SciTech Connect

    Bailey, Sean W.; Hooker, Stanford B.; Antoine, David; Franz, Bryan A.; Werdell, P. Jeremy

    2008-04-20

    Spaceborne ocean color sensors require vicarious calibration to sea-truth data to achieve accurate water-leaving radiance retrievals. The assumed requirements of an in situ data set necessary to achieve accurate vicarious calibration were set forth in a series of papers and reports developed nearly a decade ago, which were embodied in the development and site location of the Marine Optical BuoY (MOBY). Since that time, NASA has successfully used data collected by MOBY as the sole source of sea-truth data for vicarious calibration of the Sea-viewing Wide field-of-view Sensor (SeaWiFS) and Moderate Resolution Imaging Spectroradiometer instruments. In this paper, we make use of the 10-year, global time series of SeaWiFS measurements to test the sensitivity of vicarious calibration to the assumptions inherent in the in situ requirements (e.g., very low chlorophyll waters, hyperspectral measurements). Our study utilized field measurements from a variety of sources with sufficient diversity in data collection methods and geophysical variability to challenge those in situ restrictions. We found that some requirements could be relaxed without compromising the ability to vicariously calibrate to the level required for accurate water-leaving radiance retrievals from satellite-based sensors.

  19. Calibration of a time-resolved hard-x-ray detector using radioactive sources

    NASA Astrophysics Data System (ADS)

    Stoeckl, C.; Theobald, W.; Regan, S. P.; Romanofsky, M. H.

    2016-11-01

    A four-channel, time-resolved, hard x-ray detector (HXRD) has been operating at the Laboratory for Laser Energetics for more than a decade. The slope temperature of the hot-electron population in direct-drive inertial confinement fusion experiments is inferred by recording the hard x-ray radiation generated in the interaction of the electrons with the target. Measuring the energy deposited by hot electrons requires an absolute calibration of the hard x-ray detector. A novel method to obtain an absolute calibration of the HXRD using single photons from radioactive sources was developed, which uses a thermoelectrically cooled, low-noise, charge-sensitive amplifier.

  20. Primary calibrations of radionuclide solutions and sources for the EML quality assessment program

    SciTech Connect

    Fisenne, I.M.

    1993-12-31

    The quality assurance procedures established for the operation of the U.S. Department of Energy`s Environmental Measurements Laboratory (DOE-EML`s) Quality Assessment Program (QAP) are essentially the same as those that are in effect for any EML program involving radiometric measurements. All these programs have at their core the use of radionuclide standards for their instrument calibration. This paper focuses on EML`s approach to the acquisition, calibration and application of a wide range of radionuclide sources that are required to meet its programmatic needs.

  1. The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) 2005: Calibration and Targeted Sources

    NASA Astrophysics Data System (ADS)

    Truch, M. D. P.; Ade, P. A. R.; Bock, J. J.; Chapin, E. L.; Devlin, M. J.; Dicker, S.; Griffin, M.; Gundersen, J. O.; Halpern, M.; Hargrave, P. C.; Hughes, D. H.; Klein, J.; Marsden, G.; Martin, P. G.; Mauskopf, P.; Netterfield, C. B.; Olmi, L.; Pascale, E.; Patanchon, G.; Rex, M.; Scott, D.; Semisch, C.; Tucker, C.; Tucker, G. S.; Viero, M. P.; Wiebe, D. V.

    2008-07-01

    The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) operated successfully during a 100 hr flight from northern Sweden in 2005 June (BLAST05). As part of the calibration and pointing procedures, several compact sources were mapped, including solar system, Galactic, and extragalactic targets, specifically Pallas, CRL 2688, LDN 1014, IRAS 20126+4104, IRAS 21078+5211, IRAS 21307+5049, IRAS 22134+5834, IRAS 23011+6126, K3-50, W75N, and Mrk 231. One additional source, Arp 220, was observed and used as our primary calibrator. Details of the overall BLAST05 calibration procedure are discussed here. The BLAST observations of each compact source are described, flux densities and spectral energy distributions are reported, and these are compared with previous measurements at other wavelengths. The 250, 350, and 500 μm BLAST data can provide useful constraints to the amplitude and slope of the submillimeter continuum, which in turn may be useful for the improved calibration of other submillimeter instruments.

  2. Narrow Line X-Ray Calibration Source for High Resolution Microcalorimeters

    NASA Technical Reports Server (NTRS)

    Hokin, M.S.; McCammon, D.; Morgan, K.M.; Bandler, Simon Richard; Lee, S.J.; Moseley, S.H.; Smith, S.J.

    2013-01-01

    We are developing a narrow line calibration source for use with X-ray microcalorimeters. At energies below 300 electronvolts fluorescent lines are intrinsically broad, making calibration of high resolution detectors difficult. This source consists of a 405 nanometers (3 electronvolts) laser diode coupled to an optical fiber. The diode is pulsed to create approximately one hundred photons in a few microseconds. If the pulses are short compared to the rise time of the detector, they will be detected as single events with a total energy in the soft X-ray range. Poisson fluctuations in photon number per pulse create a comb of X-ray lines with 3 electronvolts spacing, so detectors with energy resolution better than 2 electronvolts are required to resolve the individual lines. Our currently unstabilized diode has a multimode width less than 1 nanometer, giving a 300 electronvolt event a Full width at half maximum (FWHM) less than 0.1 electronvolts. By varying the driving voltage, or pulse width, the source can produce a comb centered on a wide range of energies. The calibration events are produced at precisely known times. This allows continuous calibration of a flight mission without contaminating the observed spectrum and with minimal deadtime.

  3. The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) 2005: Calibration and Targeted Sources

    NASA Astrophysics Data System (ADS)

    Truch, Matthew; BLAST Collaboration

    2007-12-01

    The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) operated successfully during a 100-hour flight from northern Sweden in June 2005 (BLAST05). As part of the calibration and pointing procedures, several compact sources were mapped, including solar system, Galactic, and extragalactic targets, specifically Pallas, CRL 2688, LDN 1014, IRAS 20126+4104, IRAS 21078+5211, IRAS 21307+5049, IRAS 22134+5834, IRAS 23011+6126, K3-50, W 75N, Mrk 231, NGC 4565, and Arp 220 (this last source being our primary calibrator). The BLAST observations of each compact source are described, flux densities and spectral energy distributions are reported, and these are compared with previous measurements at other wavelengths. BLAST was particularly useful for constraining the slope of the submillimeter continuum.

  4. New detections of Galactic molecular absorption systems toward ALMA calibrator sources

    NASA Astrophysics Data System (ADS)

    Ando, Ryo; Kohno, Kotaro; Tamura, Yoichi; Izumi, Takuma; Umehata, Hideki; Nagai, Hiroshi

    2016-02-01

    We report on Atacama Large Millimeter/submillimeter Array (ALMA) detections of molecular absorption lines in Bands 3, 6, and 7 toward four radio-loud quasars, which were observed as the bandpass and complex gain calibrators. The absorption systems, three of which are newly detected, are found to be Galactic origin. Moreover, HCO absorption lines toward two objects are detected, which almost doubles the number of HCO absorption samples in the Galactic diffuse medium. In addition, high HCO-to-H13CO+ column density ratios are found, suggesting that the interstellar media (ISM) observed toward the two calibrators are in photodissociation regions, which observationally illustrates the chemistry of diffuse ISM driven by ultraviolet (UV) radiation. These results demonstrate that calibrators in the ALMA Archive are potential sources for the quest for new absorption systems and for detailed investigation of the nature of the ISM.

  5. A method for the temperature calibration of an infrared camera using water as a radiative source

    SciTech Connect

    Bower, S. M.; Kou, J.; Saylor, J. R.

    2009-09-15

    Presented here is an effective low-cost method for the temperature calibration of infrared cameras, for applications in the 0-100 deg. C range. The calibration of image gray level intensity to temperature is achieved by imaging an upwelling flow of water, the temperature of which is measured with a thermistor probe. The upwelling flow is created by a diffuser located below the water surface of a constant temperature water bath. The thermistor probe is kept immediately below the surface, and the distance from the diffuser outlet to the surface is adjusted so that the deformation of the water surface on account of the flow is small, yet the difference between the surface temperature seen by the camera and the bulk temperature measured by the thermistor is also small. The benefit of this method compared to typical calibration procedures is that, without sacrificing the quality of the calibration, relatively expensive commercial blackbodies are replaced by water as the radiative source ({epsilon}{approx_equal}0.98 for the wavelengths considered here). A heat transfer analysis is provided, which improves the accuracy of the calibration method and also provides the user with guidance to further increases in accuracy of the method.

  6. Absolute flux density calibrations of radio sources: 2.3 GHz

    NASA Technical Reports Server (NTRS)

    Freiley, A. J.; Batelaan, P. D.; Bathker, D. A.

    1977-01-01

    A detailed description of a NASA/JPL Deep Space Network program to improve S-band gain calibrations of large aperture antennas is reported. The program is considered unique in at least three ways; first, absolute gain calibrations of high quality suppressed-sidelobe dual mode horns first provide a high accuracy foundation to the foundation to the program. Second, a very careful transfer calibration technique using an artificial far-field coherent-wave source was used to accurately obtain the gain of one large (26 m) aperture. Third, using the calibrated large aperture directly, the absolute flux density of five selected galactic and extragalactic natural radio sources was determined with an absolute accuracy better than 2 percent, now quoted at the familiar 1 sigma confidence level. The follow-on considerations to apply these results to an operational network of ground antennas are discussed. It is concluded that absolute gain accuracies within + or - 0.30 to 0.40 db are possible, depending primarily on the repeatability (scatter) in the field data from Deep Space Network user stations.

  7. Development of a photochemical source for the production and calibration of acyl peroxynitrate compounds

    NASA Astrophysics Data System (ADS)

    Veres, P. R.; Roberts, J. M.

    2015-02-01

    A dynamic system for the calibration of acyl peroxynitrate compounds (APNs) has been developed in the laboratory to reduce the difficulty, required time, and stability of laboratory produced standards for difficult to synthesize APN species. In this work we present a photochemical source for the generation of APN standards: acetyl peroxynitrate (PAN), propionyl peroxynitrate (PPN), acryloyl peroxynitrate (APAN), methacryloyl peroxynitrate (MPAN) and crotonyl peroxynitrate (CPAN). APNs are generated via photolysis of a mixture of acyl chloride (RC(O)Cl) and ketone (RC(=O)R) precursor compounds in the presence of O2 and NO2. Subsequent separation by a prep-scale gas chromatograph and detection with a total NOy instrument serves to quantify the output of the APN source. Validation of the APN products was performed using iodide ion chemical ionization mass spectroscopy (I- CIMS). This method of standard production is an efficient and accurate technique for the calibration of instrumentation used to measure PAN, PPN, APAN, MPAN, and CPAN.

  8. Preliminary Calibration Report of an Apparatus to Measure Vibration Characteristics of Low Frequency Disturbance Source Devices

    NASA Technical Reports Server (NTRS)

    Russell, James W.; Marshall, Robert A.; Finley, Tom D.; Lawrence, George F.

    1994-01-01

    This report presents a description of the test apparatus and the method of testing the low frequency disturbance source characteristics of small pumps, fans, camera motors, and recorders that are typical of those used in microgravity science facilities. The test apparatus will allow both force and acceleration spectra of these disturbance devices to be obtained from acceleration measurements over the frequency range from 2 to 300 Hz. Some preliminary calibration results are presented.

  9. Development of a compact 20 MeV gamma-ray source for energy calibration at the Sudbury Neutrino Observatory

    SciTech Connect

    Poon, A.W.P.; Browne, M.C.; Robertson, R.G.H.; Waltham, C.E.; Kherani, N.P.

    1995-12-31

    The Sudbury Neutrino Observatory (SNO) is a real-time neutrino detector under construction near Sudbury, Ontario, Canada. SNO collaboration is developing various calibration sources in order to determine the detector response completely. This paper describes briefly the calibration sources being developed by the collaboration. One of these, a compact {sup 3}H(p,{gamma}){sup 4}He source, which produces 20-MeV {gamma}-rays, is described.

  10. Calibration of the CDF tile-fiber endplug calorimeters using moving radioactive sources

    SciTech Connect

    Barnes, V.; Laasanen, A.; Pompos, A.; Wilson, M.

    1998-11-01

    The use of moving radioactive gamma sources to assess, calibrate and monitor scintillating tile calorimeters is discussed, and the techniques and equipment are described. The capabilities of the technique are illustrated using Cs{sup 137} sources with the CDF Endplug Upgrade EM and Hadron calorimeters at testbeams and at a cosmic ray test stand. Source measurements of all the tiles in testbeam modules which are exact replicas of the calorimeters, predict the relative responses of EM towers to 50 GeV positrons and muons, and of Hadron towers to 50 GeV pions, with RMS accuracies of 1.3{percent}, 1.8{percent} and 2.0{percent}, respectively. Source measurements will be used in lieu of testbeam measurements for the initial calibration of all towers in the final calorimeters. Source measurements of single tiles are reproducible to 0.4{percent} and will be used to monitor gain changes of the photomultiplier tubes. {copyright} {ital 1998 American Institute of Physics.}

  11. A 220Rn source for the calibration of low-background experiments

    NASA Astrophysics Data System (ADS)

    Lang, R. F.; Brown, A.; Brown, E.; Cervantes, M.; Macmullin, S.; Masson, D.; Schreiner, J.; Simgen, H.

    2016-04-01

    We characterize two 40 kBq sources of electrodeposited 228Th for use in low-background experiments. The sources efficiently emanate 220Rn, a noble gas that can diffuse in a detector volume. 220Rn and its daughter isotopes produce α-, β-, and γ-radiation, which may used to calibrate a variety of detector responses and features, before decaying completely in only a few days. We perform various tests to place limits on the release of other long-lived isotopes. In particular, we find an emanation of < 0.008 atoms/min/kBq (90% CL) for 228Th and (1.53 ± 0.04) atoms/min/kBq for 224Ra. The sources lend themselves in particular to the calibration of detectors employing liquid noble elements such as argon and xenon. With the source mounted in a noble gas system, we demonstrate that filters are highly efficient in reducing the activity of these longer-lived isotopes further. We thus confirm the suitability of these sources even for use in next-generation experiments, such as XENON1T/XENONnT, LZ, and nEXO.

  12. SU-E-T-155: Calibration of Variable Longitudinal Strength 103Pd Brachytherapy Sources

    SciTech Connect

    Reed, J; Radtke, J; Micka, J; Culberson, W; DeWerd, L

    2015-06-15

    Purpose: Brachytherapy sources with variable longitudinal strength (VLS) allow for a customized intensity along the length of the source. These have applications in focal brachytherapy treatments of prostate cancer where dose boosting can be achieved through modulation of intra-source strengths. This work focused on development of a calibration methodology for VLS sources based on measurements and Monte Carlo (MC) simulations of five 1 cm {sup 10} {sup 3}Pd sources each containing four regions of variable {sup 103}Pd strength. Methods: The air-kerma strengths of the sources were measured with a variable-aperture free-air chamber (VAFAC). Source strengths were also measured using a well chamber. The in-air azimuthal and polar anisotropy of the sources were measured by rotating them in front of a NaI scintillation detector and were calculated with MC simulations. Azimuthal anisotropy results were normalized to their mean intensity values. Polar anisotropy results were normalized to their average transverse axis intensity values. The relative longitudinal strengths of the sources were measured via on-contact irradiations with radiochromic film, and were calculated with MC simulations. Results: The variable {sup 103}Pd loading of the sources was validated by VAFAC and well chamber measurements. Ratios of VAFAC air-kerma strengths and well chamber responses were within ±1.3% for all sources. Azimuthal anisotropy results indicated that ≥95% of the normalized values for all sources were within ±1.7% of the mean values. Polar anisotropy results indicated variations within ±0.3% for a ±7.6° angular region with respect to the source transverse axis. Locations and intensities of the {sup 103}Pd regions were validated by radiochromic film measurements and MC simulations. Conclusion: The calibration methodology developed in this work confirms that the VLS sources investigated have a high level of polar uniformity, and that the strength and longitudinal intensity can be

  13. Calibration of a microchannel plate based extreme ultraviolet grazing incident spectrometer at the Advanced Light Source.

    PubMed

    Bakeman, M S; van Tilborg, J; Sokollik, T; Baum, D; Ybarrolaza, N; Duarte, R; Toth, C; Leemans, W P

    2010-10-01

    We present the design and calibration of a microchannel plate based extreme ultraviolet spectrometer. Calibration was performed at the Advance Light Source (ALS) at the Lawrence Berkeley National Laboratory (LBNL). This spectrometer will be used to record the single shot spectrum of radiation emitted by the tapered hybrid undulator (THUNDER) undulator installed at the LOASIS GeV-class laser-plasma-accelerator. The spectrometer uses an aberration-corrected concave grating with 1200 lines/mm covering 11-62 nm and a microchannel plate detector with a CsI coated photocathode for increased quantum efficiency in the extreme ultraviolet. A touch screen interface controls the grating angle, aperture size, and placement of the detector in vacuum, allowing for high-resolution measurements over the entire spectral range.

  14. Calibration of a microchannel plate based extreme ultraviolet grazing incident spectrometer at the Advanced Light Source

    SciTech Connect

    Bakeman, M. S.; Tilborg, J. van; Sokollik, T.; Baum, D.; Ybarrolaza, N.; Duarte, R.; Toth, C.; Leemans, W. P.

    2010-10-15

    We present the design and calibration of a microchannel plate based extreme ultraviolet spectrometer. Calibration was performed at the Advance Light Source (ALS) at the Lawrence Berkeley National Laboratory (LBNL). This spectrometer will be used to record the single shot spectrum of radiation emitted by the tapered hybrid undulator (THUNDER) undulator installed at the LOASIS GeV-class laser-plasma-accelerator. The spectrometer uses an aberration-corrected concave grating with 1200 lines/mm covering 11-62 nm and a microchannel plate detector with a CsI coated photocathode for increased quantum efficiency in the extreme ultraviolet. A touch screen interface controls the grating angle, aperture size, and placement of the detector in vacuum, allowing for high-resolution measurements over the entire spectral range.

  15. The Add-A-Source Matrix Calibration of a Large Neutron Box Counter

    SciTech Connect

    Bosko, A.; Croft, S.; Philips, S.; McElroy, R.D.

    2008-07-01

    A general purpose passive neutron box counter has been designed, constructed and factory calibrated. The instrument is intended to sort and assay Transuranic Uranium (TRU) waste according to the Waste Isolation Pilot Plant (WIPP) criteria in containers ranging from drums to large boxes and crates. A multi-position Cf Add-A-Source (AAS) capability has been built into the system to determine gross matrix correction factors. The Cf source capsule runs in a U-shaped guide tube beneath the powered roller conveyor used to move the containers into the assay cavity from the loading station. The factory calibration involved measuring a wide range of matrix materials and densities in 208-liter (55 US-gal.) barrels, Standard Waste Box (SWB), Standard Large Box (SLB-2), and Ten Drum Overpack (TDOP) containers. For each container a Volume Weighted Average (VWA) rate and an AAS perturbation factor was determined and the relationship between them was established for the full range of conditions expected to be encountered operationally. In this paper we describe the calibration procedure which used Cf-252 as a surrogate for Pu-240 to map out the spatial responses for the various container-matrix combinations. A particular challenge was the scale of the measurement campaign which was directly related to the large volume of some of the containers. The reduction of the data was also challenging because for the larger items with high concentrations of hydrogen steep spatial gradients were observed in the response. For this reason simple volume-element averaging of the data to derive VWA quantities was inadequate and numerical-integration approaches of the 3-dimensional maps were explored. The response maps were also used to create point-source contributions to the Total Measurement Uncertainty (TMU), but this work is not the subject of this paper. The wide range in container size also required varying numbers of AAS interrogation position. For the drums a single AAS position was used

  16. Preliminary designs for X-ray source modifications for the Marshall Space Flight Center's X-ray calibration facility

    NASA Technical Reports Server (NTRS)

    Croft, W. L.

    1986-01-01

    The objective of this investigation is to develop preliminary designs for modifications to the X-ray source of the MSFC X-Ray Calibration Facility. Recommendations are made regarding: (1) the production of an unpolarized X-ray beam, (2) modification of the source to provide characteristic X-rays with energies up to 40 keV, and (3) addition of the capability to calibrate instruments in the extreme ultraviolet wavelength region.

  17. Rapid calibrated high-resolution hyperspectral imaging using tunable laser source

    NASA Astrophysics Data System (ADS)

    Nguyen, Lam K.; Margalith, Eli

    2009-05-01

    We present a novel hyperspectral imaging technique based on tunable laser technology. By replacing the broadband source and tunable filters of a typical NIR imaging instrument, several advantages are realized, including: high spectral resolution, highly variable field-of-views, fast scan-rates, high signal-to-noise ratio, and the ability to use optical fiber for efficient and flexible sample illumination. With this technique, high-resolution, calibrated hyperspectral images over the NIR range can be acquired in seconds. The performance of system features will be demonstrated on two example applications: detecting melamine contamination in wheat gluten and separating bovine protein from wheat protein in cattle feed.

  18. SQUID (Superconducting Quantum Interference Device) Arrays for Simultaneous Magnetic Measurements: Calibration and Source Localization Performance.

    DTIC Science & Technology

    1988-02-29

    Calibration & Source Localization 12. PERSONAL AUTHOR(S) Lloyd Kaufman, Samuel J. Williamson, and P. Costa Ribeiro 13a. TYPE OF REPORT 13b. TIME COVERED 14...Ribelro et d . 4 January 1968 SQUID Arrays Page 7 4. A Method of Verification Another way to measure the field imbalance correction ti, which at the...voltage VC for a displacement d from the detection coil’s center will be: AV ( d ) = (BclK) [ Tj - (5/2)( d /Sc)2 + (225/8)(bdSc2) 2 (6) The two unknowns in

  19. The moon as a radiometric reference source for on-orbit sensor stability calibration

    USGS Publications Warehouse

    Stone, T.C.

    2009-01-01

    The wealth of data generated by the world's Earth-observing satellites, now spanning decades, allows the construction of long-term climate records. A key consideration for detecting climate trends is precise quantification of temporal changes in sensor calibration on-orbit. For radiometer instruments in the solar reflectance wavelength range (near-UV to shortwave-IR), the Moon can be viewed as a solar diffuser with exceptional stability properties. A model for the lunar spectral irradiance that predicts the geometric variations in the Moon's brightness with ???1% precision has been developed at the U.S. Geological Survey in Flagstaff, AZ. Lunar model results corresponding to a series of Moon observations taken by an instrument can be used to stabilize sensor calibration with sub-percent per year precision, as demonstrated by the Sea-viewing Wide Field-of-view Sensor (SeaWiFS). The inherent stability of the Moon and the operational model to utilize the lunar irradiance quantity provide the Moon as a reference source for monitoring radiometric calibration in orbit. This represents an important capability for detecting terrestrial climate change from space-based radiometric measurements.

  20. FOUR PI CALIBRATION AND MODELING OF A BARE GERMANIUM DETECTOR IN A CYLINDRICAL FIELD SOURCE

    SciTech Connect

    Dewberry, R.; Young, J.

    2011-04-29

    In reference 1 the authors described {gamma}-ray holdup assay of a Mossbauer spectroscopy instrument where they utilized two axial symmetric cylindrical shell acquisitions and two disk source acquisitions to determine Am-241 and Np-237 contamination. The measured contents of the two species were determined using a general detector efficiency calibration taken from a 12-inch point source.2 The authors corrected the raw spectra for container absorption as well as for geometry corrections to transform the calibration curve to the applicable axial symmetric cylindrical source - and disk source - of contamination. The authors derived the geometry corrections with exact calculus that are shown in equations (1) and (2) of our Experimental section. A cylindrical shell (oven source) acquisition configuration is described in reference 3, where the authors disclosed this configuration to gain improved sensitivity for holdup measure of U-235 in a ten-chamber oven. The oven was a piece of process equipment used in the Savannah River Plant M-Area Uranium Fuel Fabrication plant for which a U-235 holdup measurement was necessary for its decontamination and decommissioning in 2003.4 In reference 4 the authors calibrated a bare NaI detector for these U-235 holdup measurements. In references 5 and 6 the authors calibrated a bare HpGe detector in a cylindrical shell configuration for improved sensitivity measurements of U-235 in other M-Area process equipment. Sensitivity was vastly improved compared to a close field view of the sample, with detection efficiency of greater than 1% for the 185.7-keV {gamma}-ray from U-235. In none of references 3 - 7 did the authors resolve the exact calculus descriptions of the acquisition configurations. Only the empirical efficiency for detection of the 185.7-keV photon from U-235 decay was obtained. Not until the 2010 paper of reference 1 did the authors derive a good theoretical description of the flux of photons onto the front face of a detector

  1. Calibration of the Regional Crustal Waveguide and the Retrieval of Source Parameters Using Waveform Modeling

    NASA Astrophysics Data System (ADS)

    Saikia, C. K.; Woods, B. B.; Thio, H. K.

    - Regional crustal waveguide calibration is essential to the retrieval of source parameters and the location of smaller (M<4.8) seismic events. This path calibration of regional seismic phases is strongly dependent on the accuracy of hypocentral locations of calibration (or master) events. This information can be difficult to obtain, especially for smaller events. Generally, explosion or quarry blast generated travel-time data with known locations and origin times are useful for developing the path calibration parameters, but in many regions such data sets are scanty or do not exist. We present a method which is useful for regional path calibration independent of such data, i.e. with earthquakes, which is applicable for events down to Mw = 4 and which has successfully been applied in India, central Asia, western Mediterranean, North Africa, Tibet and the former Soviet Union. These studies suggest that reliably determining depth is essential to establishing accurate epicentral location and origin time for events. We find that the error in source depth does not necessarily trade-off only with the origin time for events with poor azimuthal coverage, but with the horizontal location as well, thus resulting in poor epicentral locations. For example, hypocenters for some events in central Asia were found to move from their fixed-depth locations by about 20km. Such errors in location and depth will propagate into path calibration parameters, particularly with respect to travel times. The modeling of teleseismic depth phases (pP, sP) yields accurate depths for earthquakes down to magnitude Mw = 4.7. This Mwthreshold can be lowered to four if regional seismograms are used in conjunction with a calibrated velocity structure model to determine depth, with the relative amplitude of the Pnl waves to the surface waves and the interaction of regional sPmP and pPmP phases being good indicators of event depths. We also found that for deep events a seismic phase which follows an S

  2. Radio Frequency Plasma Discharge Lamps for Use as Stable Calibration Light Sources

    NASA Technical Reports Server (NTRS)

    McAndrew, Brendan; Cooper, John; Arecchi, Angelo; McKee, Greg; Durell, Christopher

    2012-01-01

    Stable high radiance in visible and near-ultraviolet wavelengths is desirable for radiometric calibration sources. In this work, newly available electrodeless radio-frequency (RF) driven plasma light sources were combined with research grade, low-noise power supplies and coupled to an integrating sphere to produce a uniform radiance source. The stock light sources consist of a 28 VDC power supply, RF driver, and a resonant RF cavity. The RF cavity includes a small bulb with a fill gas that is ionized by the electric field and emits light. This assembly is known as the emitter. The RF driver supplies a source of RF energy to the emitter. In commercial form, embedded electronics within the RF driver perform a continual optimization routine to maximize energy transfer to the emitter. This optimization routine continually varies the light output sinusoidally by approximately 2% over a several-second period. Modifying to eliminate this optimization eliminates the sinusoidal variation but allows the output to slowly drift over time. This drift can be minimized by allowing sufficient warm-up time to achieve thermal equilibrium. It was also found that supplying the RF driver with a low-noise source of DC electrical power improves the stability of the lamp output. Finally, coupling the light into an integrating sphere reduces the effect of spatial fluctuations, and decreases noise at the output port of the sphere.

  3. Innovative methodology for intercomparison of radionuclide calibrators using short half-life in situ prepared radioactive sources

    SciTech Connect

    Oliveira, P. A.; Santos, J. A. M.

    2014-07-15

    Purpose: An original radionuclide calibrator method for activity determination is presented. The method could be used for intercomparison surveys for short half-life radioactive sources used in Nuclear Medicine, such as{sup 99m}Tc or most positron emission tomography radiopharmaceuticals. Methods: By evaluation of the resulting net optical density (netOD) using a standardized scanning method of irradiated Gafchromic XRQA2 film, a comparison of the netOD measurement with a previously determined calibration curve can be made and the difference between the tested radionuclide calibrator and a radionuclide calibrator used as reference device can be calculated. To estimate the total expected measurement uncertainties, a careful analysis of the methodology, for the case of{sup 99m}Tc, was performed: reproducibility determination, scanning conditions, and possible fadeout effects. Since every factor of the activity measurement procedure can influence the final result, the method also evaluates correct syringe positioning inside the radionuclide calibrator. Results: As an alternative to using a calibrated source sent to the surveyed site, which requires a relatively long half-life of the nuclide, or sending a portable calibrated radionuclide calibrator, the proposed method uses a source preparedin situ. An indirect activity determination is achieved by the irradiation of a radiochromic film using {sup 99m}Tc under strictly controlled conditions, and cumulated activity calculation from the initial activity and total irradiation time. The irradiated Gafchromic film and the irradiator, without the source, can then be sent to a National Metrology Institute for evaluation of the results. Conclusions: The methodology described in this paper showed to have a good potential for accurate (3%) radionuclide calibrators intercomparison studies for{sup 99m}Tc between Nuclear Medicine centers without source transfer and can easily be adapted to other short half-life radionuclides.

  4. Source spectra, moment, and energy for recent eastern mediterranean earthquakes: calibration of international monitoring system stations

    SciTech Connect

    Mayeda, K M; Hofstetter, A; Rodgers, A J; Walter, W R

    2000-07-26

    In the past several years there have been several large (M{sub w} > 7.0) earthquakes in the eastern Mediterranean region (Gulf of Aqaba, Racha, Adana, etc.), many of which have had aftershock deployments by local seismological organizations. In addition to providing ground truth data (GT << 5 km) that is used in regional location calibration and validation, the waveform data can be used to aid in calibrating regional magnitudes, seismic discriminants, and velocity structure. For small regional events (m{sub b} << 4.5), a stable, accurate magnitude is essential in the development of realistic detection threshold curves, proper magnitude and distance amplitude correction processing, formation of an M{sub s}:m{sub b} discriminant, and accurate yield determination of clandestine nuclear explosions. Our approach provides a stable source spectra from which M{sub w} and m{sub b} can be obtained without regional magnitude biases. Once calibration corrections are obtained for earthquakes, the coda-derived source spectra exhibit strong depth-dependent spectral peaking when the same corrections are applied to explosions at the Nevada Test Site (Mayeda and Walter, 1996), chemical explosions in the recent ''Depth of Burial'' experiment in Kazahkstan (Myers et al., 1999), and the recent nuclear test in India. For events in the western U.S. we found that total seismic energy, E, scales as M{sub o}{sup 0.25} resulting in more radiated energy than would be expected under the assumptions of constant stress-drop scaling. Preliminary results for events in the Middle East region also show this behavior, which appears to be the result of intermediate spectra fall-off (f{sup 1.5}) for frequencies ranging between {approx}0.1 and 0.8 Hz for the larger events. We developed a Seismic Analysis Code (SAC) coda processing command that reads in an ASCII flat file that contains calibration information specific for a station and surrounding region, then outputs a coda-derived source spectra

  5. CBF/CMRO2 Coupling Measured with Calibrated-BOLD fMRI: Sources of Bias

    PubMed Central

    Leontiev, Oleg; Dubowitz, David J.; Buxton, Richard B.

    2007-01-01

    The coupling between cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) during brain activation can be characterized by an empirical index n, the ratio of fractional CBF changes to fractional CMRO2 changes. Measurements of n have yielded varying results, and it is not known if the observed variability is due to measurement techniques or underlying physiology. The calibrated BOLD approach using hypercapnia offers a promising tool for assessing changes in CBF/CMRO2 coupling in health and disease, but potential systematic errors have not yet been characterized. The goal of this study was to experimentally evaluate the magnitude of bias in the estimate of n that arises from the way in which a region of interest (ROI) is chosen for averaging data, and to relate this potential bias to a more general theoretical consideration of the sources of systematic errors in the calibrated BOLD experiment. Results were compared for different approaches for defining an ROI within the visual cortex based on: 1) retinotopically-defined V1; 2) a functional CBF localizer; and 3) a functional BOLD localizer. Data in V1 yielded a significantly lower estimate of n (2.45) compared to either CBF (n = 3.45) or BOLD (n = 3.18) localizers. Different statistical thresholds produced biases in estimates of n with values ranging from 3.01 (low threshold) to 4.37 (high threshold). Possible sources of the observed biases are discussed. These results underscore the importance of a critical evaluation of the methodology, and the adoption of consistent standards for applying the calibrated BOLD approach to the evaluation of CBF/CMRO2 coupling. PMID:17524665

  6. CBF/CMRO2 coupling measured with calibrated BOLD fMRI: sources of bias.

    PubMed

    Leontiev, Oleg; Dubowitz, David J; Buxton, Richard B

    2007-07-15

    The coupling between cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) during brain activation can be characterized by an empirical index n, the ratio of fractional CBF changes to fractional CMRO2 changes. Measurements of n have yielded varying results, and it is not known if the observed variability is due to measurement techniques or underlying physiology. The calibrated BOLD approach using hypercapnia offers a promising tool for assessing changes in CBF/CMRO2 coupling in health and disease, but potential systematic errors have not yet been characterized. The goal of this study was to experimentally evaluate the magnitude of bias in the estimate of n that arises from the way in which a region of interest (ROI) is chosen for averaging data and to relate this potential bias to a more general theoretical consideration of the sources of systematic errors in the calibrated BOLD experiment. Results were compared for different approaches for defining an ROI within the visual cortex based on: (1) retinotopically defined V1; (2) a functional CBF localizer; and (3) a functional BOLD localizer. Data in V1 yielded a significantly lower estimate of n (2.45) compared to either CBF (n=3.45) or BOLD (n=3.18) localizers. Different statistical thresholds produced biases in estimates of n with values ranging from 3.01 (low threshold) to 4.37 (high threshold). Possible sources of the observed biases are discussed. These results underscore the importance of a critical evaluation of the methodology, and the adoption of consistent standards for applying the calibrated BOLD approach to the evaluation of CBF/CMRO2 coupling.

  7. Calibration of Seismic Sources during a Test Cruise with the new RV SONNE

    NASA Astrophysics Data System (ADS)

    Engels, M.; Schnabel, M.; Damm, V.

    2015-12-01

    During autumn 2014, several test cruises of the brand new German research vessel SONNE were carried out before the first official scientific cruise started in December. In September 2014, BGR conducted a seismic test cruise in the British North Sea. RV SONNE is a multipurpose research vessel and was also designed for the mobile BGR 3D seismic equipment, which was tested successfully during the cruise. We spend two days for calibration of the following seismic sources of BGR: G-gun array (50 l @ 150 bar) G-gun array (50 l @ 207 bar) single GI-gun (3.4 l @ 150 bar) For this experiment two hydrophones (TC4042 from Reson Teledyne) sampling up to 48 kHz were fixed below a drifting buoy at 20 m and 60 m water depth - the sea bottom was at 80 m depth. The vessel with the seismic sources sailed several up to 7 km long profiles around the buoy in order to cover many different azimuths and distances. We aimed to measure sound pressure level (SPL) and sound exposure level (SEL) under the conditions of the shallow North Sea. Total reflections and refracted waves dominate the recorded wave field, enhance the noise level and partly screen the direct wave in contrast to 'true' deep water calibration based solely on the direct wave. Presented are SPL and RMS power results in time domain, the decay with distance along profiles, and the somehow complicated 2D sound radiation pattern modulated by topography. The shading effect of the vessel's hull is significant. In frequency domain we consider 1/3 octave levels and estimate the amount of energy in frequency ranges not used for reflection seismic processing. Results are presented in comparison of the three different sources listed above. We compare the measured SPL decay with distance during this experiment with deep water modeling of seismic sources (Gundalf software) and with published results from calibrations with other marine seismic sources under different conditions: E.g. Breitzke et al. (2008, 2010) with RV Polarstern

  8. SATELLITE-MOUNTED LIGHT SOURCES AS PHOTOMETRIC CALIBRATION STANDARDS FOR GROUND-BASED TELESCOPES

    SciTech Connect

    Albert, J.

    2012-01-15

    A significant and growing portion of systematic error on a number of fundamental parameters in astrophysics and cosmology is due to uncertainties from absolute photometric and flux standards. A path toward achieving major reduction in such uncertainties may be provided by satellite-mounted light sources, resulting in improvement in the ability to precisely characterize atmospheric extinction, and thus helping to usher in the coming generation of precision results in astronomy. Using a campaign of observations of the 532 nm pulsed laser aboard the CALIPSO satellite, collected using a portable network of cameras and photodiodes, we obtain initial measurements of atmospheric extinction, which can apparently be greatly improved by further data of this type. For a future satellite-mounted precision light source, a high-altitude balloon platform under development (together with colleagues) can provide testing as well as observational data for calibration of atmospheric uncertainties.

  9. Development of a photochemical source for the production and calibration of acyl peroxynitrate compounds

    NASA Astrophysics Data System (ADS)

    Veres, P. R.; Roberts, J. M.

    2015-05-01

    A dynamic system for the calibration of acyl peroxynitrate compounds (APNs) has been developed in the laboratory to reduce the difficulty, required time, and instability of laboratory-produced standards for difficult-to-synthesize APN species. In this work we present a photochemical source for the generation of APN standards: acetyl peroxynitrate (PAN), propionyl peroxynitrate (PPN), acryloyl peroxynitrate (APAN), methacryloyl peroxynitrate (MPAN), and crotonyl peroxynitrate (CPAN). APNs are generated via photolysis of a mixture of acyl chloride (RC(O)Cl) and ketone (RC(=O)R) precursor compounds in the presence of O2 and NO2. Subsequent separation by a prep-scale gas chromatograph and detection with a total NOy instrument serve to quantify the output of the APN source. Validation of the APN products was performed using iodide ion chemical ionization mass spectroscopy (I- CIMS). This method of standard production is an efficient and accurate technique for the calibration of instrumentation used to measure PAN, PPN, APAN, MPAN, and CPAN.

  10. Modeling Study of a Proposed Field Calibration Source Using K-40 and High-Z Targets for Sodium Iodide Detectors.

    PubMed

    Rogers, Jeremy; Marianno, Craig; Kallenbach, Gene; Trevino, Jose

    2016-06-01

    Calibration sources based on the primordial isotope potassium-40 (K) have reduced controls on the source's activity due to its terrestrial ubiquity and very low specific activity. Potassium-40's beta emissions and 1,460.8 keV gamma ray can be used to induce K-shell fluorescence x rays in high-Z metals between 60 and 80 keV. A gamma ray calibration source that uses potassium chloride salt and a high-Z metal to create a two-point calibration for a sodium iodide field gamma spectroscopy instrument is thus proposed. The calibration source was designed in collaboration with the Sandia National Laboratory using the Monte Carlo N-Particle eXtended (MCNPX) transport code. Two methods of x-ray production were explored. First, a thin high-Z layer (HZL) was interposed between the detector and the potassium chloride-urethane source matrix. Second, bismuth metal powder was homogeneously mixed with a urethane binding agent to form a potassium chloride-bismuth matrix (KBM). The bismuth-based source was selected as the development model because it is inexpensive, nontoxic, and outperforms the high-Z layer method in simulation. Based on the MCNPX studies, sealing a mixture of bismuth powder and potassium chloride into a thin plastic case could provide a light, inexpensive field calibration source.

  11. SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: PLANETS AND CELESTIAL CALIBRATION SOURCES

    SciTech Connect

    Weiland, J. L.; Odegard, N.; Hill, R. S.; Greason, M. R.; Wollack, E.; Hinshaw, G.; Kogut, A.; Bennett, C. L.; Gold, B.; Larson, D.; Dunkley, J.; Halpern, M.; Komatsu, E.; Limon, M.; Meyer, S. S.; Nolta, M. R.; Smith, K. M.; Spergel, D. N.

    2011-02-01

    We present WMAP seven-year observations of bright sources which are often used as calibrators at microwave frequencies. Ten objects are studied in five frequency bands (23-94 GHz): the outer planets (Mars, Jupiter, Saturn, Uranus, and Neptune) and five fixed celestial sources (Cas A, Tau A, Cyg A, 3C274, and 3C58). The seven-year analysis of Jupiter provides temperatures which are within 1{sigma} of the previously published WMAP five-year values, with slightly tighter constraints on variability with orbital phase (0.2% {+-} 0.4%), and limits (but no detections) on linear polarization. Observed temperatures for both Mars and Saturn vary significantly with viewing geometry. Scaling factors are provided which, when multiplied by the Wright Mars thermal model predictions at 350 {mu}m, reproduce WMAP seasonally averaged observations of Mars within {approx}2%. An empirical model is described which fits brightness variations of Saturn due to geometrical effects and can be used to predict the WMAP observations to within 3%. Seven-year mean temperatures for Uranus and Neptune are also tabulated. Uncertainties in Uranus temperatures are 3%-4% in the 41, 61, and 94 GHz bands; the smallest uncertainty for Neptune is 8% for the 94 GHz band. Intriguingly, the spectrum of Uranus appears to show a dip at {approx}30 GHz of unidentified origin, although the feature is not of high statistical significance. Flux densities for the five selected fixed celestial sources are derived from the seven-year WMAP sky maps and are tabulated for Stokes I, Q, and U, along with polarization fraction and position angle. Fractional uncertainties for the Stokes I fluxes are typically 1% to 3%. Source variability over the seven-year baseline is also estimated. Significant secular decrease is seen for Cas A and Tau A: our results are consistent with a frequency-independent decrease of about 0.53% per year for Cas A and 0.22% per year for Tau A. We present WMAP polarization data with uncertainties of a

  12. Performance of thin CaSO4:Dy pellets for calibration of a Sr90+Y90 source

    NASA Astrophysics Data System (ADS)

    Oliveira, M. L.; Caldas, L. V. E.

    2007-09-01

    Because of the radionuclide long half-life, Sr90+Y90, plane or concave sources, utilized in brachytherapy, have to be calibrated initially by the manufacturer and then routinely while they are utilized. Plane applicators can be calibrated against a conventional extrapolation chamber, but concave sources, because of their geometry, should be calibrated using relative dosimeters, as thermoluminescent (TL) materials. Thin CaSO4:Dy pellets are produced at IPEN specially for beta radiation detection. Previous works showed the feasibility of this material in the dosimetry of Sr90+Y90 sources in a wide range of absorbed dose in air. The aim of this work was to study the usefulness of these pellets for the calibration of a Sr90+Y90 concave applicator. To reach this objective, a special phantom was designed and manufactured in PTFE with semi spherical geometry. Because of the dependence of the TL response on the mass of the pellet, the response of each pellet was normalized by its mass in order to reduce the dispersion on TL response. Important characteristics of this material were obtained in reference of a standard Sr90+Y90 source, and the pellets were calibrated against a plane applicator; then they were utilized to calibrate the concave applicator.

  13. Modeling study of a proposed field calibration source using K-40 and high-Z targets for sodium iodide detectors

    DOE PAGES

    Rogers, Jeremy; Marianno, Craig; Kallenbach, Gene; ...

    2016-06-01

    Calibration sources based on the primordial isotope potassium-40 (40K) have reduced controls on the source’s activity due to its terrestrial ubiquity and very low specific activity. Potassium–40’s beta emissions and 1,460.8 keV gamma ray can be used to induce K-shell fluorescence x rays in high-Z metals between 60 and 80 keV. A gamma ray calibration source that uses potassium chloride salt and a high-Z metal to create a two-point calibration for a sodium iodide field gamma spectroscopy instrument is thus proposed. The calibration source was designed in collaboration with the Sandia National Laboratory using the Monte Carlo N-Particle eXtended (MCNPX)more » transport code. Two methods of x-ray production were explored. First, a thin high-Z layer (HZL) was interposed between the detector and the potassium chloride-urethane source matrix. Second, bismuth metal powder was homogeneously mixed with a urethane binding agent to form a potassium chloride-bismuth matrix (KBM). The bismuth-based source was selected as the development model because it is inexpensive, nontoxic, and outperforms the high-Z layer method in simulation. As a result, based on the MCNPX studies, sealing a mixture of bismuth powder and potassium chloride into a thin plastic case could provide a light, inexpensive field calibration source.« less

  14. Modeling study of a proposed field calibration source using K-40 and high-Z targets for sodium iodide detectors

    SciTech Connect

    Rogers, Jeremy; Marianno, Craig; Kallenbach, Gene; Trevino, Jose

    2016-06-01

    Calibration sources based on the primordial isotope potassium-40 (40K) have reduced controls on the source’s activity due to its terrestrial ubiquity and very low specific activity. Potassium–40’s beta emissions and 1,460.8 keV gamma ray can be used to induce K-shell fluorescence x rays in high-Z metals between 60 and 80 keV. A gamma ray calibration source that uses potassium chloride salt and a high-Z metal to create a two-point calibration for a sodium iodide field gamma spectroscopy instrument is thus proposed. The calibration source was designed in collaboration with the Sandia National Laboratory using the Monte Carlo N-Particle eXtended (MCNPX) transport code. Two methods of x-ray production were explored. First, a thin high-Z layer (HZL) was interposed between the detector and the potassium chloride-urethane source matrix. Second, bismuth metal powder was homogeneously mixed with a urethane binding agent to form a potassium chloride-bismuth matrix (KBM). The bismuth-based source was selected as the development model because it is inexpensive, nontoxic, and outperforms the high-Z layer method in simulation. As a result, based on the MCNPX studies, sealing a mixture of bismuth powder and potassium chloride into a thin plastic case could provide a light, inexpensive field calibration source.

  15. Heavy ion beams from an Alphatross source for use in calibration and testing of diagnostics

    NASA Astrophysics Data System (ADS)

    Ward, R. J.; Brown, G. M.; Ho, D.; Stockler, B. F. O. F.; Freeman, C. G.; Padalino, S. J.; Regan, S. P.

    2016-10-01

    Ion beams from the 1.7 MV Pelletron Accelerator at SUNY Geneseo have been used to test and calibrate many inertial confinement fusion (ICF) diagnostics and high energy density physics (HEDP) diagnostics used at the Laboratory for Laser Energetics (LLE). The ion source on this accelerator, a radio-frequency (RF) alkali-metal charge exchange source called an Alphatross, is designed to produce beams of hydrogen and helium isotopes. There is interest in accelerating beams of carbon, oxygen, argon, and other heavy ions for use in testing several diagnostics, including the Time Resolved Tandem Faraday Cup (TRTF). The feasibility of generating these heavy ion beams using the Alphatross source will be reported. Small amounts of various gases are mixed into the helium plasma in the ion source bottle. A velocity selector is used to allow the desired ions to pass into the accelerator. As the heavy ions pass through the stripper canal of the accelerator, they emerge in a variety of charge states. The energy of the ion beam at the high-energy end of the accelerator will vary as a function of the charge state, however the maximum energy deliverable to target is limited by the maximum achievable magnetic field produced by the accelerator's steering magnet. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  16. Exploring a Black Body Source as an Absolute Radiometric Calibration Standard and Comparison with a NIST Traced Lamp Standard

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Chrien, Thomas; Sarture, Chuck

    2001-01-01

    Radiometric calibration of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) is required for the scientific research and application objectives pursued with the spectroscopic measurements. Specifically calibration is required for: inter-comparison of AVIRIS data measured at different locations and at different times; analysis of AVIRIS data with data measured by other instruments; and analysis of AVIRIS data in conjunction with computer models. The primary effect of radiometric calibration is conversion of AVIRIS instrument response values (digitized numbers, or DN) to units of absolute radiance. For example, a figure shows the instrument response spectrum measured by AVIRIS over a portion of Rogers Dry Lake, California, and another figure shows the same spectrum calibrated to radiance. Only the calibrated spectrum may be quantitatively analyzed for science research and application objectives. Since the initial development of the AVIRIS instrument-radiometric calibration has been based upon a 1000-W irradiance lamp with a calibration traced to the National Institute of Standards and Technology (NIST). There are several advantages to this irradiance-lamp calibration approach. First, the considerable effort of NIST backs up the calibration. Second, by changing the distance to the lamp, the output can closely span the radiance levels measured by AVIRIS. Third, this type of standard is widely used. Fourth, these calibrated lamps are comparatively inexpensive. Conversely, there are several disadvantages to this approach as well. First, the lamp is not a primary standard. Second, the lamp output characteristics may change in an unknown manner through time. Third, it is difficult to assess, constrain, or improve the calibration uncertainty delivered with the lamp. In an attempt to explore the effect and potentially address some of these disadvantages a set of analyses and measurements comparing an irradiance lamp with a black-body source have been completed

  17. Analysis and Calibration of Sources of Electronic Error in PSD Sensor Response

    PubMed Central

    Rodríguez-Navarro, David; Lázaro-Galilea, José Luis; Bravo-Muñoz, Ignacio; Gardel-Vicente, Alfredo; Tsirigotis, Georgios

    2016-01-01

    In order to obtain very precise measurements of the position of agents located at a considerable distance using a sensor system based on position sensitive detectors (PSD), it is necessary to analyze and mitigate the factors that generate substantial errors in the system’s response. These sources of error can be divided into electronic and geometric factors. The former stem from the nature and construction of the PSD as well as the performance, tolerances and electronic response of the system, while the latter are related to the sensor’s optical system. Here, we focus solely on the electrical effects, since the study, analysis and correction of these are a prerequisite for subsequently addressing geometric errors. A simple calibration method is proposed, which considers PSD response, component tolerances, temperature variations, signal frequency used, signal to noise ratio (SNR), suboptimal operational amplifier parameters, and analog to digital converter (ADC) quantitation SNRQ, etc. Following an analysis of these effects and calibration of the sensor, it was possible to correct the errors, thus rendering the effects negligible, as reported in the results section. PMID:27136562

  18. Study for the analysis of the observations, and numerical data representing the planets as far-infrared calibration sources

    NASA Technical Reports Server (NTRS)

    Wu, Shi Tsan; Zhou, Minggang

    1994-01-01

    The existing radiative transfer and inversion programs will be modified for application to the atmospheres of Uranus, Neptune, and Jupiter. The programs will be employed for analysis of KAO planetary observations in order to develop far infrared photometric calibration standards. This work will be carried out on MSFC computers. The expected end product of this task is a working program for analysis of the observations, and numerical data representing the planets as far-infrared calibration sources.

  19. GOSAT-OCO-2 synergetic CO2 observations over calibration & validation sites and large emission sources

    NASA Astrophysics Data System (ADS)

    Kuze, A.; Shiomi, K.; Suto, H.; Kataoka, F.; Crisp, D.; Schwandner, F. M.; Bruegge, C. J.; Taylor, T.; Kawakami, S.

    2015-12-01

    GOSAT and OCO-2 have different observation strategies. TANSO-FTS onboard GOSAT has wide spectral coverage from SWIR to TIR and an agile pointing system at the expense of spatial context, while OCO-2 targets CO2with higher spatial resolution using imaging grating spectrometers. Since the early phase of the two projects, both teams have worked in calibration and validation to demonstrate the effectiveness of satellite greenhouse gases observation. In 2008, the pre-launch cross-calibration agreement between GOSAT and OCO radiometers was better than 2% when measuring the traceable GOSAT calibration sphere (Sakuma et. al, 2010). Since GOSAT's launch in 2009, annual joint vicarious calibration campaigns at the Railroad Valley (RRV) playa have estimated radiometric degradation factors with time at an uncertainty of 7%. (Kuze et al., 2014). After OCO-2 launch, two independent measurements can now be compared to distinguish common forward calculation errors such as molecule absorption line parameters, solar lines and light-path modification by aerosol scattering from instrument-specific errors. On 25 Mach 2015, both GOSAT and OCO-2 targeted RRV simultaneously. The measured radiance spectra at the top of the atmosphere agree within 5% for all common bands. On June 29 and July 1 during the 7th RRV campaign, coincidence observation of GOSAT, OCO-2, AJAX airplane, radiosonde, and FTS and radiometers on the ground, provided surface albedo, BRDF, temperature, humidity CO2 and CH4 density to demonstrate consistency between forward radiative transfer calculation and satellite measured data. Both GOSAT and OCO-2 have been regularly targeting the TCCON site at Lamont and large emission sources such as mega cities and oil fields and glint over the ocean. Retrieved parameters such as surface albedo, pressure, column averaged mole fraction and aerosol related parameters can be compared firstly where aerosol optical thickness is low and topography is flat, and then over aerosol

  20. Medicina array demonstrator: calibration and radiation pattern characterization using a UAV-mounted radio-frequency source

    NASA Astrophysics Data System (ADS)

    Pupillo, G.; Naldi, G.; Bianchi, G.; Mattana, A.; Monari, J.; Perini, F.; Poloni, M.; Schiaffino, M.; Bolli, P.; Lingua, A.; Aicardi, I.; Bendea, H.; Maschio, P.; Piras, M.; Virone, G.; Paonessa, F.; Farooqui, Z.; Tibaldi, A.; Addamo, G.; Peverini, O. A.; Tascone, R.; Wijnholds, S. J.

    2015-06-01

    One of the most challenging aspects of the new-generation Low-Frequency Aperture Array (LFAA) radio telescopes is instrument calibration. The operational LOw-Frequency ARray (LOFAR) instrument and the future LFAA element of the Square Kilometre Array (SKA) require advanced calibration techniques to reach the expected outstanding performance. In this framework, a small array, called Medicina Array Demonstrator (MAD), has been designed and installed in Italy to provide a test bench for antenna characterization and calibration techniques based on a flying artificial test source. A radio-frequency tone is transmitted through a dipole antenna mounted on a micro Unmanned Aerial Vehicle (UAV) (hexacopter) and received by each element of the array. A modern digital FPGA-based back-end is responsible for both data-acquisition and data-reduction. A simple amplitude and phase equalization algorithm is exploited for array calibration owing to the high stability and accuracy of the developed artificial test source. Both the measured embedded element patterns and calibrated array patterns are found to be in good agreement with the simulated data. The successful measurement campaign has demonstrated that a UAV-mounted test source provides a means to accurately validate and calibrate the full-polarized response of an antenna/array in operating conditions, including consequently effects like mutual coupling between the array elements and contribution of the environment to the antenna patterns. A similar system can therefore find a future application in the SKA-LFAA context.

  1. GT0 Explosion Sources for IMS Infrasound Calibration: Charge Design and Yield Estimation from Near-source Observations

    NASA Astrophysics Data System (ADS)

    Gitterman, Y.; Hofstetter, R.

    2014-03-01

    Three large-scale on-surface explosions were conducted by the Geophysical Institute of Israel (GII) at the Sayarim Military Range, Negev desert, Israel: about 82 tons of strong high explosives in August 2009, and two explosions of about 10 and 100 tons of ANFO explosives in January 2011. It was a collaborative effort between Israel, CTBTO, USA and several European countries, with the main goal to provide fully controlled ground truth (GT0) infrasound sources, monitored by extensive observations, for calibration of International Monitoring System (IMS) infrasound stations in Europe, Middle East and Asia. In all shots, the explosives were assembled like a pyramid/hemisphere on dry desert alluvium, with a complicated explosion design, different from the ideal homogenous hemisphere used in similar experiments in the past. Strong boosters and an upward charge detonation scheme were applied to provide more energy radiated to the atmosphere. Under these conditions the evaluation of the actual explosion yield, an important source parameter, is crucial for the GT0 calibration experiment. Audio-visual, air-shock and acoustic records were utilized for interpretation of observed unique blast effects, and for determination of blast wave parameters suited for yield estimation and the associated relationships. High-pressure gauges were deployed at 100-600 m to record air-blast properties, evaluate the efficiency of the charge design and energy generation, and provide a reliable estimation of the charge yield. The yield estimators, based on empirical scaled relations for well-known basic air-blast parameters—the peak pressure, impulse and positive phase duration, as well as on the crater dimensions and seismic magnitudes, were analyzed. A novel empirical scaled relationship for the little-known secondary shock delay was developed, consistent for broad ranges of ANFO charges and distances, which facilitates using this stable and reliable air-blast parameter as a new potential

  2. Preparation and characterisation of ceramic-based thoron sources for thoron calibration chamber.

    PubMed

    Csordás, A; Fábián, F; Horváth, M; Hegedűs, M; Somlai, J; Kovács, T

    2015-11-01

    The aim of this study is to explore the correlations between the properties of the source's material and the thoron flux produced. This means a complex procedure that involves morphological characterisation (the determination of specific surface area and pore size distribution) and thoron emanation and exhalation measurements as well. In this work, the preparation of 27 thoron sources has been carried out. Three types of ceramics with different morphological properties were used as a matrix material with three different thorium contents. Spheres were formed from the dollop, and they were fired at different temperatures (200, 600 and 900°C). The phase analysis of the samples was performed by powder X-ray diffraction. The pore size distribution was determined by mercury penetration. The thoron emanation was measured using an accumulation chamber; the measured thoron emanation coefficients were from 0.34 ± 0.03 to 7.69 ± 0.13 %. Based on the results, the preparation parameters of the thoron source optimised for the calibration procedure have been given.

  3. Broadband calibration of the R/V Marcus G. Langseth four-string seismic sources

    NASA Astrophysics Data System (ADS)

    Tolstoy, M.; Diebold, J.; Doermann, L.; Nooner, S.; Webb, S. C.; Bohnenstiehl, D. R.; Crone, T. J.; Holmes, R. C.

    2009-08-01

    The R/V Marcus G. Langseth is the first 3-D seismic vessel operated by the U.S. academic community. With up to a four-string, 36-element source and four 6-km-long solid state hydrophone arrays, this vessel promises significant new insights into Earth science processes. The potential impact of anthropogenic sound sources on marine life is an important topic to the marine seismic community. To ensure that operations fully comply with existing and future marine mammal permitting requirements, a calibration experiment was conducted in the Gulf of Mexico in 2007-2008. Results are presented from deep (˜1.6 km) and shallow (˜50 m) water sites, obtained using the full 36-element (6600 cubic inches) seismic source. This array configuration will require the largest safety radii, and the deep and shallow sites provide two contrasting operational environments. Results show that safety radii and the offset between root-mean-square and sound exposure level measurements were highly dependent on water depth.

  4. Dealing with the size-of-source effect in the calibration of direct-reading radiation thermometer

    SciTech Connect

    Saunders, P.

    2013-09-11

    The majority of general-purpose low-temperature handheld radiation thermometers are severely affected by the size-of-source effect (SSE). Calibration of these instruments is pointless unless the SSE is accounted for in the calibration process. Traditional SSE measurement techniques, however, are costly and time consuming, and because the instruments are direct-reading in temperature, traditional SSE results are not easily interpretable, particularly by the general user. This paper describes a simplified method for measuring the SSE, suitable for second-tier calibration laboratories and requiring no additional equipment, and proposes a means of reporting SSE results on a calibration certificate that should be easily understood by the non-specialist user.

  5. A calibrator based on the use of low-coherent light source straightness interferometer and compensation method.

    PubMed

    Lin, Shyh-Tsong; Yeh, Sheng-Lih; Chiu, Chi-Shang; Huang, Mou-Shan

    2011-10-24

    A calibrator utilizing a low-coherent light source straightness interferometer and a compensation method is introduced for straightness measurements in this paper. Where the interference pattern, which is modulated by an envelope function, generated by the interferometer undergoes a shifting as the Wolaston prism of the interferometer experiences a lateral displacement, and the compensation method senses the displacement by driving the prism back to the position to restore the pattern. A setup, which is with a measurement sensitivity of 36.6°/μm, constructed for realizing the calibrator is demonstrated. The experimental results from the uses of the setup reveal that the setup is with a measurement resolution and stability of 0.019 and 0.08 μm, respectively, validate the calibrator, and confirm the calibrator's applicability of straightness measurements and advantage of extensible working distance.

  6. A radio telescope for the calibration of radio sources at 32 gigahertz

    NASA Technical Reports Server (NTRS)

    Gatti, M. S.; Stewart, S. R.; Bowen, J. G.; Paulsen, E. B.

    1994-01-01

    A 1.5-m-diameter radio telescope has been designed, developed, and assembled to directly measure the flux density of radio sources in the 32-GHz (Ka-band) frequency band. The main goal of the design and development was to provide a system that could yield the greatest absolute accuracy yet possible with such a system. The accuracy of the measurements have a heritage that is traceable to the National Institute of Standards and Technology. At the present time, the absolute accuracy of flux density measurements provided by this telescope system, during Venus observations at nearly closest approach to Earth, is plus or minus 5 percent, with an associated precision of plus or minus 2 percent. Combining a cooled high-electron mobility transistor low-noise amplifier, twin-beam Dicke switching antenna, and accurate positioning system resulted in a state-of-the-art system at 32 GHz. This article describes the design and performance of the system as it was delivered to the Owens Valley Radio Observatory to support direct calibrations of the strongest radio sources at Ka-band.

  7. Development of a low energy ion source for ROSINA ion mode calibration

    SciTech Connect

    Rubin, Martin; Altwegg, Kathrin; Jaeckel, Annette; Balsiger, Hans

    2006-10-15

    The European Rosetta mission on its way to comet 67P/Churyumov-Gerasimenko will remain for more than a year in the close vicinity (1 km) of the comet. The two ROSINA mass spectrometers on board Rosetta are designed to analyze the neutral and ionized volatile components of the cometary coma. However, the relative velocity between the comet and the spacecraft will be minimal and also the velocity of the outgassing particles is below 1 km/s. This combination leads to very low ion energies in the surrounding plasma of the comet, typically below 20 eV. Additionally, the spacecraft may charge up to a few volts in this environment. In order to simulate such plasma and to calibrate the mass spectrometers, a source for ions with very low energies had to be developed for the use in the laboratory together with the different gases expected at the comet. In this paper we present the design of this ion source and we discuss the physical parameters of the ion beam like sensitivity, energy distribution, and beam shape. Finally, we show the first ion measurements that have been performed together with one of the two mass spectrometers.

  8. Calibrating nonlinear volcano deformation source parameters in FEMs: The pinned mesh perturbation method. (Invited)

    NASA Astrophysics Data System (ADS)

    Masterlark, T.; Stone, J.; Feigl, K.

    2010-12-01

    The internal structure, loading processes, and effective boundary conditions of a volcano control the deformation that we observe at the Earth’s surface. Forward models of these internal structures and processes allow us to predict the surface deformation. In practice, we are faced with the inverse situation of using surface observations (e.g., InSAR and GPS) to characterize the inaccessible internal structures and processes. Distortions of these characteristics are tied to our ability to: 1) identify and resolve the internal structure; 2) simulate the internal processes over a problem domain having this internal structure; and 3) calibrate parameters that describe these internal processes to the observed deformation. Relatively simple analytical solutions for deformation sources (such as a pressurized magma chamber) embedded in a homogeneous, elastic half-space are commonly used to simulate observed volcano deformation, because they are computationally inexpensive, and thus easily integrated into inverse analyses that seek to characterize the source position and magnitude. However, the half-space models generally do not adequately represent internal distributions of material properties and complex geometric configurations, such as topography, of volcano deformational systems. These incompatibilities are known to severely bias both source parameter estimations and forward model calculations of deformation and stress. Alternatively, a Finite Element Model (FEM) can simulate the elastic response to a pressurized magma chamber over a domain having arbitrary geometry and distribution of material properties. However, the ability to impose perturbations of the source position parameters and automatically reconstruct an acceptable mesh has been an obstacle to implementing FEM-based nonlinear inverse methods to estimate the position of a deformation source. Using InSAR-observed deflation of Okmok volcano, Alaska, during its 1997 eruption as an example, we present the

  9. Metrological tests of a 200 L calibration source for HPGE detector systems for assay of radioactive waste drums.

    PubMed

    Boshkova, T; Mitev, K

    2016-03-01

    In this work we present test procedures, approval criteria and results from two metrological inspections of a certified large volume (152)Eu source (drum about 200L) intended for calibration of HPGe gamma assay systems used for activity measurement of radioactive waste drums. The aim of the inspections was to prove the stability of the calibration source during its working life. The large volume source was designed and produced in 2007. It consists of 448 identical sealed radioactive sources (modules) apportioned in 32 transparent plastic tubes which were placed in a wooden matrix which filled the drum. During the inspections the modules were subjected to tests for verification of their certified characteristics. The results show a perfect compliance with the NIST basic guidelines for the properties of a radioactive certified reference material (CRM) and demonstrate the stability of the large volume CRM-drum after 7 years of operation.

  10. Dissolved plume attenuation with DNAPL source remediation, aqueous decay and volatilization — Analytical solution, model calibration and prediction uncertainty

    NASA Astrophysics Data System (ADS)

    Parker, Jack C.; Park, Eungyu; Tang, Guoping

    2008-11-01

    A vertically-integrated analytical model for dissolved phase transport is described that considers a time-dependent DNAPL source based on the upscaled dissolution kinetics model of Parker and Park with extensions to consider time-dependent source zone biodecay, partial source mass reduction, and remediation-enhanced source dissolution kinetics. The model also considers spatial variability in aqueous plume decay, which is treated as the sum of aqueous biodecay and volatilization due to diffusive transport and barometric pumping through the unsaturated zone. The model is implemented in Excel/VBA coupled with (1) an inverse solution that utilizes prior information on model parameters and their uncertainty to condition the solution, and (2) an error analysis module that computes parameter covariances and total prediction uncertainty due to regression error and parameter uncertainty. A hypothetical case study is presented to evaluate the feasibility of calibrating the model from limited noisy field data. The results indicate that prediction uncertainty increases significantly over time following calibration, primarily due to propagation of parameter uncertainty. However, differences between the predicted performance of source zone partial mass reduction and the known true performance were reasonably small. Furthermore, a clear difference is observed between the predicted performance for the remedial action scenario versus that for a no-action scenario, which is consistent with the true system behavior. The results suggest that the model formulation can be effectively utilized to assess monitored natural attenuation and source remediation options if careful attention is given to model calibration and prediction uncertainty issues.

  11. Close-geometry efficiency calibration of p-type HPGe detectors with a Cs-134 point source.

    PubMed

    DeFelice, P; Fazio, A; Vidmar, T; Korun, M

    2006-01-01

    When close-geometry detector calibration is required in gamma-ray spectrometry, single-line emitters are usually used in order to avoid true coincidence summing effects. We managed to overcome this limitation by developing a method for the determination of the efficiency of p-type HPGe detectors in close-geometry with a calibrated Cs-134 point source. No separate determination of coincidence summing correction factors is required and a single measurement furnishes the full-energy-peak efficiencies in the 475-1365 keV energy range.

  12. SU-F-BRA-09: New Efficient Method for Xoft Axxent Electronic Brachytherapy Source Calibration by Pre-Characterizing Surface Applicators

    SciTech Connect

    Pai, S

    2015-06-15

    Purpose: The objective is to improve the efficiency and efficacy of Xoft™ Axxent™ electronic brachytherapy (EBT) calibration of the source & surface applicator using AAPM TG-61 formalism. Methods: Current method of Xoft EBT source calibration involves determination of absolute dose rate of the source in each of the four conical surface applicators using in-air chamber measurements & TG61 formalism. We propose a simplified TG-61 calibration methodology involving initial characterization of surface cone applicators. This is accomplished by calibrating dose rates for all 4 surface applicator sets (for 10 sources) which establishes the “applicator output ratios” with respect to the selected reference applicator (20 mm applicator). After the initial time, Xoft™ Axxent™ source TG61 Calibration is carried out only in the reference applicator. Using the established applicator output ratios, dose rates for other applicators will be calculated. Results: 200 sources & 8 surface applicator sets were calibrated cumulatively using a Standard Imaging A20 ion-chamber in accordance with manufacturer-recommended protocols. Dose rates of 10, 20, 35 & 50mm applicators were normalized to the reference (20mm) applicator. The data in Figure 1 indicates that the normalized dose rate variation for each applicator for all 200 sources is better than ±3%. The average output ratios are 1.11, 1.02 and 0.49 for the 10 mm,35 mm and 50 mm applicators, respectively, which are in good agreement with the manufacturer’s published output ratios of 1.13, 1.02 and 0.49. Conclusion: Our measurements successfully demonstrate the accuracy of a new calibration method using a single surface applicator for Xoft EBT sources and deriving the dose rates of other applicators. The accuracy of the calibration is improved as this method minimizes the source position variation inside the applicator during individual source calibrations. The new method significantly reduces the calibration time to less

  13. A comparison of absolute calibrations of a radiation thermometer based on a monochromator and a tunable source

    NASA Astrophysics Data System (ADS)

    Keawprasert, T.; Anhalt, K.; Taubert, D. R.; Sperling, A.; Schuster, M.; Nevas, S.

    2013-09-01

    An LP3 radiation thermometer was absolutely calibrated at a newly developed monochromator-based set-up and the TUneable Lasers in Photometry (TULIP) facility of PTB in the wavelength range from 400 nm to 1100 nm. At both facilities, the spectral radiation of the respective sources irradiates an integrating sphere, thus generating uniform radiance across its precision aperture. The spectral irradiance of the integrating sphere is determined via an effective area of a precision aperture and a Si trap detector, traceable to the primary cryogenic radiometer of PTB. Due to the limited output power from the monochromator, the absolute calibration was performed with the measurement uncertainty of 0.17 % (k = 1), while the respective uncertainty at the TULIP facility is 0.14 %. Calibration results obtained by the two facilities were compared in terms of spectral radiance responsivity, effective wavelength and integral responsivity. It was found that the measurement results in integral responsivity at the both facilities are in agreement within the expanded uncertainty (k = 2). To verify the calibration accuracy, the absolutely calibrated radiation thermometer was used to measure the thermodynamic freezing temperatures of the PTB gold fixed-point blackbody.

  14. A comparison of absolute calibrations of a radiation thermometer based on a monochromator and a tunable source

    SciTech Connect

    Keawprasert, T.; Anhalt, K.; Taubert, D. R.; Sperling, A.; Schuster, M.; Nevas, S.

    2013-09-11

    An LP3 radiation thermometer was absolutely calibrated at a newly developed monochromator-based set-up and the TUneable Lasers in Photometry (TULIP) facility of PTB in the wavelength range from 400 nm to 1100 nm. At both facilities, the spectral radiation of the respective sources irradiates an integrating sphere, thus generating uniform radiance across its precision aperture. The spectral irradiance of the integrating sphere is determined via an effective area of a precision aperture and a Si trap detector, traceable to the primary cryogenic radiometer of PTB. Due to the limited output power from the monochromator, the absolute calibration was performed with the measurement uncertainty of 0.17 % (k= 1), while the respective uncertainty at the TULIP facility is 0.14 %. Calibration results obtained by the two facilities were compared in terms of spectral radiance responsivity, effective wavelength and integral responsivity. It was found that the measurement results in integral responsivity at the both facilities are in agreement within the expanded uncertainty (k= 2). To verify the calibration accuracy, the absolutely calibrated radiation thermometer was used to measure the thermodynamic freezing temperatures of the PTB gold fixed-point blackbody.

  15. Sensitivity calibration of an imaging extreme ultraviolet spectrometer-detector system for determining the efficiency of broadband extreme ultraviolet sources

    NASA Astrophysics Data System (ADS)

    Fuchs, S.; Rödel, C.; Krebs, M.; Hädrich, S.; Bierbach, J.; Paz, A. E.; Kuschel, S.; Wünsche, M.; Hilbert, V.; Zastrau, U.; Förster, E.; Limpert, J.; Paulus, G. G.

    2013-02-01

    We report on the absolute sensitivity calibration of an extreme ultraviolet (XUV) spectrometer system that is frequently employed to study emission from short-pulse laser experiments. The XUV spectrometer, consisting of a toroidal mirror and a transmission grating, was characterized at a synchrotron source in respect of the ratio of the detected to the incident photon flux at photon energies ranging from 15.5 eV to 99 eV. The absolute calibration allows the determination of the XUV photon number emitted by laser-based XUV sources, e.g., high-harmonic generation from plasma surfaces or in gaseous media. We have demonstrated high-harmonic generation in gases and plasma surfaces providing 2.3 μW and μJ per harmonic using the respective generation mechanisms.

  16. CONSTRUCTION OF A CALIBRATED PROBABILISTIC CLASSIFICATION CATALOG: APPLICATION TO 50k VARIABLE SOURCES IN THE ALL-SKY AUTOMATED SURVEY

    SciTech Connect

    Richards, Joseph W.; Starr, Dan L.; Miller, Adam A.; Bloom, Joshua S.; Brink, Henrik; Crellin-Quick, Arien; Butler, Nathaniel R.

    2012-12-15

    With growing data volumes from synoptic surveys, astronomers necessarily must become more abstracted from the discovery and introspection processes. Given the scarcity of follow-up resources, there is a particularly sharp onus on the frameworks that replace these human roles to provide accurate and well-calibrated probabilistic classification catalogs. Such catalogs inform the subsequent follow-up, allowing consumers to optimize the selection of specific sources for further study and permitting rigorous treatment of classification purities and efficiencies for population studies. Here, we describe a process to produce a probabilistic classification catalog of variability with machine learning from a multi-epoch photometric survey. In addition to producing accurate classifications, we show how to estimate calibrated class probabilities and motivate the importance of probability calibration. We also introduce a methodology for feature-based anomaly detection, which allows discovery of objects in the survey that do not fit within the predefined class taxonomy. Finally, we apply these methods to sources observed by the All-Sky Automated Survey (ASAS), and release the Machine-learned ASAS Classification Catalog (MACC), a 28 class probabilistic classification catalog of 50,124 ASAS sources in the ASAS Catalog of Variable Stars. We estimate that MACC achieves a sub-20% classification error rate and demonstrate that the class posterior probabilities are reasonably calibrated. MACC classifications compare favorably to the classifications of several previous domain-specific ASAS papers and to the ASAS Catalog of Variable Stars, which had classified only 24% of those sources into one of 12 science classes.

  17. A new facility for the synchrotron radiation-based calibration of transfer radiation sources in the ultraviolet and vacuum ultraviolet spectral range

    SciTech Connect

    Thornagel, Reiner; Fliegauf, Rolf; Klein, Roman Kroth, Simone; Paustian, Wolfgang; Richter, Mathias

    2015-01-15

    The Physikalisch-Technische Bundesanstalt (PTB) has a long tradition in the calibration of radiation sources in the ultraviolet and vacuum ultraviolet spectral range, with traceability to calculable synchrotron radiation. Within this context, new instrumentation in the PTB laboratory at the Metrology Light Source (MLS) has been put into operation that opens up extended and improved calibration possibilities. A new facility for radiation source calibrations has been set up in the spectral range from 7 nm to 400 nm based on a combined normal incidence-grazing incidence monochromator. The facility can be used for the calibration of transfer sources in terms of spectral radiant intensity or mean spectral radiance, with traceability to the MLS primary source standard. We describe the design and performance of the experimental station and give examples of some commissioning results.

  18. High-Precision Calibration of Electron Beam Energy from the Hefei Light Source Using Spin Resonant Depolarization

    NASA Astrophysics Data System (ADS)

    Lan, Jie-Qin; Xu, Hong-Liang

    2014-12-01

    The electron beam energy at the Hefei Light Source (HLS) in the National Synchrotron Radiation Laboratory is highly precisely calibrated by using the method of spin resonant depolarization for the first time. The spin tune and the beam energy are determined by sweeping the frequency of a radial rf stripline oscillating magnetic field to artificially excite a spin resonance and depolarize the beam. The resonance signal is recognized by observing the sudden change of the Touschek loss counting rate of the beam. The possible systematic errors of the experiment are presented and the accuracy of the calibrated energy is shown to be about 10-4. A series of measurements show that the energy stability of the machine is of the order of 9 × 10-3.

  19. SOLAR/SOLSPEC: Scientific Objectives, Instrument Performance and Its Absolute Calibration Using a Blackbody as Primary Standard Source

    NASA Astrophysics Data System (ADS)

    Thuillier, G.; Foujols, T.; Bolsée, D.; Gillotay, D.; Hersé, M.; Peetermans, W.; Decuyper, W.; Mandel, H.; Sperfeld, P.; Pape, S.; Taubert, D. R.; Hartmann, J.

    2009-06-01

    SOLAR is a set of three solar instruments measuring the total and spectral absolute irradiance from 16 nm to 3080 nm for solar, atmospheric and climatology physics. It is an external payload for the COLUMBUS laboratory launched on 7 February 2008. The mission’s primary objective is the measurement of the solar irradiance with the highest possible accuracy, and its variability using the following instruments: SOL-ACES (SOLar Auto-Calibrating EUV/UV Spectrophotometers) consists of four grazing incidence planar gratings measuring from 16 nm to 220 nm; SOLSPEC (SOLar SPECtrum) consists of three double gratings spectrometers, covering the range 165 nm to 3080 nm; and SOVIM (SOlar Variability Irradiance Monitor) is combining two types of absolute radiometers and three-channel filter - radiometers. SOLSPEC and SOL-ACES have been calibrated by primary standard radiation sources of the Physikalisch-Technische Bundesanstalt (PTB). Below we describe SOLSPEC, and its performance.

  20. WE-D-9A-06: Open Source Monitor Calibration and Quality Control Software for Enterprise Display Management

    SciTech Connect

    Bevins, N; Vanderhoek, M; Lang, S; Flynn, M

    2014-06-15

    Purpose: Medical display monitor calibration and quality control present challenges to medical physicists. The purpose of this work is to demonstrate and share experiences with an open source package that allows for both initial monitor setup and routine performance evaluation. Methods: A software package, pacsDisplay, has been developed over the last decade to aid in the calibration of all monitors within the radiology group in our health system. The software is used to calibrate monitors to follow the DICOM Grayscale Standard Display Function (GSDF) via lookup tables installed on the workstation. Additional functionality facilitates periodic evaluations of both primary and secondary medical monitors to ensure satisfactory performance. This software is installed on all radiology workstations, and can also be run as a stand-alone tool from a USB disk. Recently, a database has been developed to store and centralize the monitor performance data and to provide long-term trends for compliance with internal standards and various accrediting organizations. Results: Implementation and utilization of pacsDisplay has resulted in improved monitor performance across the health system. Monitor testing is now performed at regular intervals and the software is being used across multiple imaging modalities. Monitor performance characteristics such as maximum and minimum luminance, ambient luminance and illuminance, color tracking, and GSDF conformity are loaded into a centralized database for system performance comparisons. Compliance reports for organizations such as MQSA, ACR, and TJC are generated automatically and stored in the same database. Conclusion: An open source software solution has simplified and improved the standardization of displays within our health system. This work serves as an example method for calibrating and testing monitors within an enterprise health system.

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

    NASA Astrophysics Data System (ADS)

    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. New analytical approach to calibrate the co-axial HPGe detectors including correction for source matrix self-attenuation.

    PubMed

    Badawi, Mohamed S; Gouda, Mona M; Nafee, Sherif S; El-Khatib, Ahmed M; El-Mallah, Ekram A

    2012-12-01

    To calibrate the co-axial HPGe semiconductor detectors, we introduce a new theoretical approach based on the Direct Statistical method proposed by Selim and Abbas (1995, 1996) to calculate the full-energy peak efficiency for cylindrical detectors. The present method depends on the accurate analytical calculation of the average path length covered by the photon inside the detector active volume and the geometrical solid angle Ω, to obtain a simple formula for the efficiency. In addition, the self attenuation coefficient of the source matrix (with a radius greater than the detector's radius), the attenuation factors of the source container and the detector housing materials are also treated by calculating the average path length within these materials. (152)Eu aqueous radioactive sources covering the energy range from 121 to 1408 keV were used. Remarkable agreement between the measured and the calculated efficiencies was achieved with discrepancies less than 2%.

  3. TU-AB-201-09: Calibration of An Element of a New Directional Pd-103 Planar Source Array

    SciTech Connect

    Aima, M; Culberson, W; Reed, J; DeWerd, L

    2015-06-15

    Purpose: The CivaSheet™ is a new directional Pd-103 planar source array, with a variable number of discrete source elements referred to as “dots”. Each dot consists of a polymer capsule containing {sup 103}Pd and a gold shield that attenuates radiation on one side of the device to define hot and cold dose regions. Fluorescence from the gold shield is observed in the dot spectrum. Since CivaSheet™ is a planar directional source, conventional methods used for calibration of azimuthally symmetric sources are not applicable. The purpose of this work is to establish an air-kerma-strength standard and a transfer to a well chamber for clinical calibration. Methods: Primary air-kerma strength measurement of the dots was performed using a variable-aperture free-air chamber (VAFAC). Charge measurements were recorded using a well chamber with a custom insert. Anisotropy measurements were performed using a Sodium-Iodide detector. Spectral measurements were performed using a low-energy germanium detector and compared to a source without gold. The dot geometry was modeled using the MCNP6 radiation transport code. Results: Air-kerma strength measurements of a batch of four dots performed with the VAFAC were within ±1.5% of the average measured value and the measurement precision was within ±0.5%. Anisotropy measurements indicated uniform emission within the measurement uncertainty for the solid angle defining the VAFAC aperture used. Charge measurements of each dot using the well chamber in four cardinal angle source orientations were within ±1.5% of the average measured values. The spectral study of a dot resulted in identification of fluorescence from the gold shield and primary spectral energies that were compared to MCNP6 simulations. Conclusion: Calibration procedures for the new directional Pd-103 source dot were established for future clinical use, based on the results of experimental and Monte Carlo investigations. This work was partially supported by NCI

  4. Development of pyroelectric neutron source for calibration of neutrino and dark matter detectors

    NASA Astrophysics Data System (ADS)

    Chepurnov, A. S.; Ionidi, V. Y.; Gromov, M. B.; Kirsanov, M. A.; Klyuyev, A. S.; Kubankin, A. S.; Oleinik, A. N.; Shchagin, A. V.; Vokhmyanina, K. A.

    2017-01-01

    The laboratory experimental setup for development of pyroelectric neutron generator for calibration of neutrino and dark matter detectors for direct search of Weakly Interacting Massive Particles (WIMP) has been developed. The setup allows providing and controlling the neutrons generation process realized during d-d nuclear fusion. It is shown that the neutrons with energy 2.45 MeV can be generated starting from a level of electric potential generated by pyroelectric crystal about 30 kV, in contrast to the typical neutron tubes which need the applied outer high voltage level about 100 kV.

  5. Improvement in the practical implementation of neutron source strength calibration using prompt gamma rays.

    PubMed

    Khabaz, Rahim; Rene Vega-Carrillo, Hector

    2013-08-01

    In this study, the neutron emission rate from neutron sources using prompt gamma rays in hydrogen was determined, and several improvements were applied. Using Monte Carlo calculations, the best positions for the source, moderator and detector relative to each other were selected. For (241)Am-Be and (252)Cf sources, the sizes for polyethylene spheres with the highest efficiency were 12- and 10-inch, respectively. In addition, a new shielding cone was designed to account for scattered neutrons and gamma rays. The newly designed shielding cone, which is 45 cm in length, provided suitable attenuation for the source radiation.

  6. Calibration of a wide-field frequency-domain fluorescence lifetime microscopy system using light emitting diodes as light sources.

    PubMed

    Elder, A D; Frank, J H; Swartling, J; Dai, X; Kaminski, C F

    2006-11-01

    High brightness light emitting diodes are an inexpensive and versatile light source for wide-field frequency-domain fluorescence lifetime imaging microscopy. In this paper a full calibration of an LED based fluorescence lifetime imaging microscopy system is presented for the first time. A radio-frequency generator was used for simultaneous modulation of light emitting diode (LED) intensity and the gain of an intensified charge coupled device (CCD) camera. A homodyne detection scheme was employed to measure the demodulation and phase shift of the emitted fluorescence, from which phase and modulation lifetimes were determined at each image pixel. The system was characterized both in terms of its sensitivity to measure short lifetimes (500 ps to 4 ns), and its capability to distinguish image features with small lifetime differences. Calibration measurements were performed in quenched solutions containing Rhodamine 6G dye and the results compared to several independent measurements performed with other measurement methodologies, including time correlated single photon counting, time gated detection, and acousto optical modulator (AOM) based modulation of excitation sources. Results are presented from measurements and simulations. The effects of limited signal-to-noise ratios, baseline drifts and calibration errors are discussed in detail. The implications of limited modulation bandwidth of high brightness, large area LED devices ( approximately 40 MHz for devices used here) are presented. The results show that phase lifetime measurements are robust down to sub ns levels, whereas modulation lifetimes are prone to errors even at large signal-to-noise ratios. Strategies for optimizing measurement fidelity are discussed. Application of the fluorescence lifetime imaging microscopy system is illustrated with examples from studies of molecular mixing in microfluidic devices and targeted drug delivery research.

  7. Radio source calibration for the Very Small Array and other cosmic microwave background instruments at around 30 GHz

    NASA Astrophysics Data System (ADS)

    Hafez, Yaser A.; Davies, Rod D.; Davis, Richard J.; Dickinson, Clive; Battistelli, Elia S.; Blanco, Francisco; Cleary, Kieran; Franzen, Thomas; Genova-Santos, Ricardo; Grainge, Keith; Hobson, Michael P.; Jones, Michael E.; Lancaster, Katy; Lasenby, Anthony N.; Padilla-Torres, Carmen P.; Rubiño-Martin, José Alberto; Rebolo, Rafael; Saunders, Richard D. E.; Scott, Paul F.; Taylor, Angela C.; Titterington, David; Tucci, Marco; Watson, Robert A.

    2008-08-01

    Accurate calibration of data is essential for the current generation of cosmic microwave background (CMB) experiments. Using data from the Very Small Array (VSA), we describe procedures which will lead to an accuracy of 1 per cent or better for experiments such as the VSA and CBI. Particular attention is paid to the stability of the receiver systems, the quality of the site and frequent observations of reference sources. At 30 GHz the careful correction for atmospheric emission and absorption is shown to be essential for achieving 1 per cent precision. The sources for which a 1 per cent relative flux density calibration was achieved included Cas A, Cyg A, Tau A and NGC 7027 and the planets Venus, Jupiter and Saturn. A flux density, or brightness temperature in the case of the planets, was derived at 33 GHz relative to Jupiter which was adopted as the fundamental calibrator. A spectral index at ~30 GHz is given for each. Cas A, Tau A, NGC 7027 and Venus were examined for variability. Cas A was found to be decreasing at 0.394 +/- 0.019 per cent yr-1 over the period 2001 March to 2004 August. In the same period Tau A was decreasing at 0.22 +/- 0.07 per cent yr-1. A survey of the published data showed that the planetary nebula NGC 7027 decreased at 0.16 +/- 0.04 per cent yr-1 over the period 1967-2003. Venus showed an insignificant (1.5 +/- 1.3 per cent) variation with Venusian illumination. The integrated polarization of Tau A at 33 GHz was found to be 7.8 +/- 0.6 per cent at position angle =148° +/- 3°.

  8. Calibration of the KRISS reference ionization chamber for certification of ²²²Rn gaseous sources.

    PubMed

    Lee, J M; Lee, K B; Lee, S H; Oh, P J; Park, T S; Kim, B C; Lee, M S

    2013-11-01

    A primary measurement system for gaseous (222)Rn based on the defined solid angle counting method has recently been constructed at KRISS and the reference ionization chamber used to measure the activities of gamma-emitting single radionuclides was adopted as a secondary standard for gaseous (222)Rn. A 20 mL flame-sealed glass ampoule source from the primary measurement system was used to calibrate the ionization chamber for (222)Rn. The (222)Rn efficiency of the ionization chamber was compared with that calculated by using a photon energy-dependent efficiency curve and that measured by using a standard (226)Ra solution. From the comparisons we draw the conclusion that the reference ionization chamber for gamma-emitting radionuclides can be a suitable secondary measurement system for gaseous (222)Rn sources.

  9. Using cross correlations to calibrate lensing source redshift distributions: Improving cosmological constraints from upcoming weak lensing surveys

    SciTech Connect

    De Putter, Roland; Doré, Olivier; Das, Sudeep

    2014-01-10

    Cross correlations between the galaxy number density in a lensing source sample and that in an overlapping spectroscopic sample can in principle be used to calibrate the lensing source redshift distribution. In this paper, we study in detail to what extent this cross-correlation method can mitigate the loss of cosmological information in upcoming weak lensing surveys (combined with a cosmic microwave background prior) due to lack of knowledge of the source distribution. We consider a scenario where photometric redshifts are available and find that, unless the photometric redshift distribution p(z {sub ph}|z) is calibrated very accurately a priori (bias and scatter known to ∼0.002 for, e.g., EUCLID), the additional constraint on p(z {sub ph}|z) from the cross-correlation technique to a large extent restores the cosmological information originally lost due to the uncertainty in dn/dz(z). Considering only the gain in photo-z accuracy and not the additional cosmological information, enhancements of the dark energy figure of merit of up to a factor of four (40) can be achieved for a SuMIRe-like (EUCLID-like) combination of lensing and redshift surveys, where SuMIRe stands for Subaru Measurement of Images and Redshifts). However, the success of the method is strongly sensitive to our knowledge of the galaxy bias evolution in the source sample and we find that a percent level bias prior is needed to optimize the gains from the cross-correlation method (i.e., to approach the cosmology constraints attainable if the bias was known exactly).

  10. Fiber optic microphone having a pressure sensing reflective membrane and a voltage source for calibration purpose

    NASA Technical Reports Server (NTRS)

    Zuckerwar, Allan J. (Inventor); Cuomo, Frank W. (Inventor); Robbins, William E. (Inventor)

    1993-01-01

    A fiber optic microphone is provided for measuring fluctuating pressures. An optical fiber probe having at least one transmitting fiber for transmitting light to a pressure-sensing membrane and at least one receiving fiber for receiving light reflected from a stretched membrane is provided. The pressure-sensing membrane may be stretched for high frequency response. Further, a reflecting surface of the pressure-sensing membrane may have dimensions which substantially correspond to dimensions of a cross section of the optical fiber probe. Further, the fiber optic microphone can be made of materials for use in high temperature environments, for example greater than 1000 F. A fiber optic probe is also provided with a back plate for damping membrane motion. The back plate further provides a means for on-line calibration of the microphone.

  11. The LBA Calibrator Survey of Southern Compact Extragalactic Radio Sources - LCS1

    NASA Technical Reports Server (NTRS)

    Petrov, Leonid; Phillips, Chris; Bertarini, Alessandra; Murphy, Tara; Sadler, Elaine M.

    2011-01-01

    We present a catalogue of accurate positions and correlated flux densities for 410 flat-spectrum, compact extragalactic radio sources previously detected in the Australia Telescope 20 GHz (AT20G) survey. The catalogue spans the declination range [-90deg, -40deg] and was constructed from four 24-h very long baseline interferometry (VLBI) observing sessions with the Australian Long Baseline Array at 8.3 GHz. The VLBI detection rate in these experiments is 97 per cent, the median uncertainty of the source positions is 2.6 mas and the median correlated flux density on projected baselines longer than 1000 km is 0.14 Jy. The goals of this work are (1) to provide a pool of southern sources with positions accurate to a few milliarcsec, which can be used for phase-referencing observations, geodetic VLBI and space navigation; (2) to extend the complete flux-limited sample of compact extragalactic sources to the Southern hemisphere; and (3) to investigate the parsec-scale properties of high-frequency selected sources from the AT20G survey. As a result of this VLBI campaign, the number of compact radio sources south of declination -40deg which have measured VLBI correlated flux densities and positions known to milliarcsec accuracy has increased by a factor of 3.5.

  12. Spectrally and Radiometrically Stable Wide-Band on Board Calibration Source for In-Flight Data Validation in Imaging Spectroscopy Applications

    NASA Technical Reports Server (NTRS)

    Coles, J. B.; Richardson, Brandon S.; Eastwood, Michael L.; Sarture, Charles M.; Quetin, Gregory R.; Hernandez, Marco A.; Kroll, Linley A.; Nolte, Scott H.; Porter, Michael D.; Green, Robert O.

    2011-01-01

    The quality of the quantitative spectral data collected by an imaging spectrometer instrument is critically dependent upon the accuracy of the spectral and radiometric calibration of the system. In order for the collected spectra to be scientifically useful, the calibration of the instrument must be precisely known not only prior to but during data collection. Thus, in addition to a rigorous in-lab calibration procedure, the airborne instruments designed and built by the NASA/JPL Imaging Spectroscopy Group incorporate an on board calibrator (OBC) system with the instrument to provide auxiliary in-use system calibration data. The output of the OBC source illuminates a target panel on the backside of the foreoptics shutter both before and after data collection. The OBC and in-lab calibration data sets are then used to validate and post-process the collected spectral image data. The resulting accuracy of the spectrometer output data is therefore integrally dependent upon the stability of the OBC source. In this paper we describe the design and application of the latest iteration of this novel device developed at NASA/JPL which integrates a halogen-cycle source with a precisely designed fiber coupling system and a fiber-based intensity monitoring feedback loop. The OBC source in this Airborne Testbed Spectrometer was run over a period of 15 hours while both the radiometric and spectral stabilities of the output were measured and demonstrated stability to within 1% of nominal.

  13. Film dosimetry calibration method for pulsed-dose-rate brachytherapy with an 192Ir source.

    PubMed

    Schwob, Nathan; Orion, Itzhak

    2007-05-01

    192Ir sources have been widely used in clinical brachytherapy. An important challenge is to perform dosimetric measurements close to the source despite the steep dose gradient. The common, inexpensive silver halide film is a classic two-dimensional integrator dosimeter and would be an attractive solution for these dose measurements. The main disadvantage of film dosimetry is the film response to the low-energy photon. Since the photon energy spectrum is known to vary with depth, the sensitometric curves are expected to be dependent on depth. The purpose of this study is to suggest a correction method for silver halide film dosimetry that overcomes the response changes at different depths. Sensitometric curves have been obtained at different depths with verification film near a 1 Ci 192Ir pulsed-dose-rate source. The depth dependence of the film response was observed and a correction function was established. The suitability of the method was tested through measurement of the radial dose profile and radial dose function. The results were compared to Monte Carlo-simulated values according to the TG43 formalism. Monte Carlo simulations were performed separately for the beta and gamma source emissions, using the EGS4 code system, including the low-energy photon and electron transport optimization procedures. The beta source emission simulation showed that the beta dose contribution could be neglected and therefore the film-depth dependence could not be attributed to this part of the source radioactivity. The gamma source emission simulations included photon-spectra collection at several depths. The results showed a depth-dependent softening of the photon spectrum that can explain the film-energy dependence.

  14. In situ calibration of a light source in a sensor device

    DOEpatents

    Okandan, Murat; Serkland, Darwin k.; Merchant, Bion J.

    2015-12-29

    A sensor device is described herein, wherein the sensor device includes an optical measurement system, such as an interferometer. The sensor device further includes a low-power light source that is configured to emit an optical signal having a constant wavelength, wherein accuracy of a measurement output by the sensor device is dependent upon the optical signal having the constant wavelength. At least a portion of the optical signal is directed to a vapor cell, the vapor cell including an atomic species that absorbs light having the constant wavelength. A photodetector captures light that exits the vapor cell, and generates an electrical signal that is indicative of intensity of the light that exits the vapor cell. A control circuit controls operation of the light source based upon the electrical signal, such that the light source emits the optical signal with the constant wavelength.

  15. Calibration of the nonlinear ring model at the Diamond Light Source

    NASA Astrophysics Data System (ADS)

    Bartolini, R.; Martin, I. P. S.; Rehm, G.; Schmidt, F.

    2011-05-01

    Nonlinear beam dynamics plays a crucial role in defining the performance of a storage ring. The beam lifetime, the injection efficiency, and the dynamic and momentum apertures available to the beam are optimized during the design phase by a proper optimization of the linear lattice and of the distribution of sextupole families. The correct implementation of the design model, especially the nonlinear part, is a nontrivial accelerator physics task. Several parameters of the nonlinear dynamics can be used to compare the real machine with the model and eventually to correct the accelerator. Most of these parameters are extracted from the analysis of turn-by-turn data after the excitation of betatron oscillations of the particles in the ring. We present the experimental results of the campaign of measurements carried out at the Diamond storage ring to characterize the nonlinear beam dynamics. A combination of frequency map analysis with the detuning with momentum measurements has allowed for a precise calibration of the nonlinear model that can accurately reproduce the nonlinear beam dynamics in Diamond.

  16. Calibration of Fast Fiber-Optic Beam Loss Monitors for the Advanced Photon Source Storage Ring Superconducting Undulators

    SciTech Connect

    Dooling, J.; Harkay, K.; Ivanyushenkov, Y.; Sajaev, V.; Xiao, A.; Vella, Andrea K.

    2015-01-01

    We report on the calibration and use of fast fiber-optic (FO) beam loss monitors (BLMs) in the Advanced Photon Source storage ring (SR). A superconducting undulator prototype (SCU0) has been operating in SR Sector 6 (“ID6”) since the beginning of CY2013, and another undulator SCU1 (a 1.1-m length undulator that is three times the length of SCU0) is scheduled for installation in Sector 1 (“ID1”) in 2015. The SCU0 main coil often quenches during beam dumps. MARS simulations have shown that relatively small beam loss (<1 nC) can lead to temperature excursions sufficient to cause quenchingwhen the SCU0windings are near critical current. To characterize local beam losses, high-purity fused-silica FO cables were installed in ID6 on the SCU0 chamber transitions and in ID1 where SCU1 will be installed. These BLMs aid in the search for operating modes that protect the SCU structures from beam-loss-induced quenching. In this paper, we describe the BLM calibration process that included deliberate beam dumps at locations of BLMs. We also compare beam dump events where SCU0 did and did not quench.

  17. Validation Tests of Open-Source Procedures for Digital Camera Calibration and 3d Image-Based Modelling

    NASA Astrophysics Data System (ADS)

    Toschi, I.; Rivola, R.; Bertacchini, E.; Castagnetti, C.; Dubbini, M.; Capra, A.

    2013-07-01

    Among the many open-source software solutions recently developed for the extraction of point clouds from a set of un-oriented images, the photogrammetric tools Apero and MicMac (IGN, Institut Géographique National) aim to distinguish themselves by focusing on the accuracy and the metric content of the final result. This paper firstly aims at assessing the accuracy of the simplified and automated calibration procedure offered by the IGN tools. Results obtained with this procedure were compared with those achieved with a test-range calibration approach using a pre-surveyed laboratory test-field. Both direct and a-posteriori validation tests turned out successfully showing the stability and the metric accuracy of the process, even when low textured or reflective surfaces are present in the 3D scene. Afterwards, the possibility of achieving accurate 3D models from the subsequently extracted dense point clouds is also evaluated. Three different types of sculptural elements were chosen as test-objects and "ground-truth" data were acquired with triangulation laser scanners. 3D models derived from point clouds oriented with a simplified relative procedure show a suitable metric accuracy: all comparisons delivered a standard deviation of millimeter-level. The use of Ground Control Points in the orientation phase did not improve significantly the accuracy of the final 3D model, when a small figure-like corbel was used as test-object.

  18. Air kerma standard for calibration of well-type chambers in Brazil using {sup 192}Ir HDR sources and its traceability

    SciTech Connect

    Di Prinzio, Renato; Almeida, Carlos Eduardo de

    2009-03-15

    In Brazil there are over 100 high dose rate (HDR) brachytherapy facilities using well-type chambers for the determination of the air kerma rate of {sup 192}Ir sources. This paper presents the methodology developed and extensively tested by the Laboratorio de Ciencias Radiologicas (LCR) and presently in use to calibrate those types of chambers. The system was initially used to calibrate six well-type chambers of brachytherapy services, and the maximum deviation of only 1.0% was observed between the calibration coefficients obtained and the ones in the calibration certificate provided by the UWADCL. In addition to its traceability to the Brazilian National Standards, the whole system was taken to University of Wisconsin Accredited Dosimetry Calibration Laboratory (UWADCL) for a direct comparison and the same formalism to calculate the air kerma was used. The comparison results between the two laboratories show an agreement of 0.9% for the calibration coefficients. Three Brazilian well-type chambers were calibrated at the UWADCL, and by LCR, in Brazil, using the developed system and a clinical HDR machine. The results of the calibration of three well chambers have shown an agreement better than 1.0%. Uncertainty analyses involving the measurements made both at the UWADCL and LCR laboratories are discussed.

  19. Design, fabrication, and calibration of curved integral coils for measuring transfer function, uniformity, and effective length of LBL ALS (Lawrence Berkeley Laboratory Advanced Light Source) Booster Dipole Magnets

    SciTech Connect

    Green, M.I.; Nelson, D.; Marks, S.; Gee, B.; Wong, W.; Meneghetti, J.

    1989-03-01

    A matched pair of curved integral coils has been designed, fabricated and calibrated at Lawrence Berkeley Laboratory for measuring Advanced Light Source (ALS) Booster Dipole Magnets. Distinctive fabrication and calibration techniques are described. The use of multifilar magnet wire in fabrication integral search coils is described. Procedures used and results of AC and DC measurements of transfer function, effective length and uniformity of the prototype booster dipole magnet are presented in companion papers. 8 refs.

  20. A multi-source satellite data approach for modelling Lake Turkana water level: Calibration and validation using satellite altimetry data

    USGS Publications Warehouse

    Velpuri, N.M.; Senay, G.B.; Asante, K.O.

    2012-01-01

    Lake Turkana is one of the largest desert lakes in the world and is characterized by high degrees of interand intra-annual fluctuations. The hydrology and water balance of this lake have not been well understood due to its remote location and unavailability of reliable ground truth datasets. Managing surface water resources is a great challenge in areas where in-situ data are either limited or unavailable. In this study, multi-source satellite-driven data such as satellite-based rainfall estimates, modelled runoff, evapotranspiration, and a digital elevation dataset were used to model Lake Turkana water levels from 1998 to 2009. Due to the unavailability of reliable lake level data, an approach is presented to calibrate and validate the water balance model of Lake Turkana using a composite lake level product of TOPEX/Poseidon, Jason-1, and ENVISAT satellite altimetry data. Model validation results showed that the satellitedriven water balance model can satisfactorily capture the patterns and seasonal variations of the Lake Turkana water level fluctuations with a Pearson's correlation coefficient of 0.90 and a Nash-Sutcliffe Coefficient of Efficiency (NSCE) of 0.80 during the validation period (2004-2009). Model error estimates were within 10% of the natural variability of the lake. Our analysis indicated that fluctuations in Lake Turkana water levels are mainly driven by lake inflows and over-the-lake evaporation. Over-the-lake rainfall contributes only up to 30% of lake evaporative demand. During the modelling time period, Lake Turkana showed seasonal variations of 1-2m. The lake level fluctuated in the range up to 4m between the years 1998-2009. This study demonstrated the usefulness of satellite altimetry data to calibrate and validate the satellite-driven hydrological model for Lake Turkana without using any in-situ data. Furthermore, for Lake Turkana, we identified and outlined opportunities and challenges of using a calibrated satellite-driven water balance

  1. A new scanning system for alpha decay events as calibration sources for range-energy relation in nuclear emulsion

    NASA Astrophysics Data System (ADS)

    Yoshida, J.; Kinbara, S.; Mishina, A.; Nakazawa, K.; Soe, M. K.; Theint, A. M. M.; Tint, K. T.

    2017-03-01

    A new scanning system named "Vertex picker" has been developed to rapid collect alpha decay events, which are calibration sources for the range-energy relation in nuclear emulsion. A computer-controlled optical microscope scans emulsion layers exhaustively, and a high-speed and high-resolution camera takes their micrographs. A dedicated image processing picks out vertex-like shapes. Practical operations of alpha decay search were demonstrated by emulsion sheets of the KEK-PS E373 experiment. Alpha decays of nearly 28 events were detected in eye-check work on a PC monitor per hour. This yield is nearly 20 times more effective than that by the conventional eye-scan method. The speed and quality is acceptable for the coming new experiment, J-PARC E07.

  2. Applications of an 88Y/Be photoneutron calibration source to dark matter and neutrino experiments.

    PubMed

    Collar, J I

    2013-05-24

    The low-energy monochromatic neutron emission from an (88)Y/Be source can be exploited to mimic the few keV(nr) nuclear recoils expected from low-mass weakly interacting massive particles and coherent scattering of neutrinos off nuclei. Using this source, a

  3. Calibration and Validation of Nonpoint Source Pollution and Erosion Comparison Tool,N- SPECT, for Tropical Conditions

    NASA Astrophysics Data System (ADS)

    Fares, A.; Cheng, C. L.; Dogan, A.

    2006-12-01

    Impaired water quality caused by agriculture, urbanization, and spread of invasive species has been identified as a major factor in the degradation of coastal ecosystems in the tropics. Watershed-scale nonpoint source pollution models facilitate in evaluating effective management practices to alleviate the negative impacts of different land-use changes. The Non-Point Source Pollution and Erosion Comparison Tool (N-SPECT) is a newly released watershed model that was not previously tested under tropical conditions. The two objectives of this study were to: i) calibrate and validate N-SPECT for the Hanalei Watershed of the Hawai`ian island of Kaua`i; ii) evaluate the performance of N-SPECT under tropical conditions using the sensitivity analysis approach. Hanalei watershed has one of the wettest points on earth, Mt. Waialeale with an average annual rainfall of 11,000 mm. This rainfall decreases to 2,000 mm at the outlet of the watershed near the coast. Number of rain days is one of the major input parameters that influences N-SPECT's simulation results. This parameter was used to account for plant canopy interception losses. The watershed was divided into sub- basins to accurately distribute the number of rain days throughout the watershed. Total runoff volume predicted by the model compared well with measured data. The model underestimated measured runoff by 1% for calibration period and 5% for validation period due to higher intensity precipitation in the validation period. Sensitivity analysis revealed that the model was most sensitive to the number of rain days, followed by canopy interception, and least sensitive to the number of sub-basins. The sediment and water quality portion of the model is currently being evaluated.

  4. Development of Fiber Fabry-Perot Interferometers as Stable Near-infrared Calibration Sources for High Resolution Spectrographs

    NASA Astrophysics Data System (ADS)

    Halverson, Samuel; Mahadevan, Suvrath; Ramsey, Lawrence; Hearty, Fred; Wilson, John; Holtzman, Jon; Redman, Stephen; Nave, Gillian; Nidever, David; Nelson, Matt; Venditti, Nick; Bizyaev, Dmitry; Fleming, Scott

    2014-05-01

    We discuss the ongoing development of single-mode fiber Fabry-Perot (FFP) Interferometers as precise astro-photonic calibration sources for high precision radial velocity (RV) spectrographs. FFPs are simple, inexpensive, monolithic units that can yield a stable and repeatable output spectrum. An FFP is a unique alternative to a traditional etalon, as the interferometric cavity is made of single-mode fiber rather than an air-gap spacer. This design allows for excellent collimation, high spectral finesse, rigid mechanical stability, insensitivity to vibrations, and no need for vacuum operation. The device we have tested is a commercially available product from Micron Optics. Our development path is targeted towards a calibration source for the Habitable-Zone Planet Finder (HPF), a near-infrared spectrograph designed to detect terrestrial-mass planets around low-mass stars, but this reference could also be used in many existing and planned fiber-fed spectrographs as we illustrate using the Apache Point Observatory Galactic Evolution Experiment (APOGEE) instrument. With precise temperature control of the fiber etalon, we achieve a thermal stability of 100 $\\mu$K and associated velocity uncertainty of 22 cm s$^{-1}$. We achieve a precision of $\\approx$2 m s$^{-1}$ in a single APOGEE fiber over 12 hours using this new photonic reference after removal of systematic correlations. This high precision (close to the expected photon-limited floor) is a testament to both the excellent intrinsic wavelength stability of the fiber interferometer and the stability of the APOGEE instrument design. Overall instrument velocity precision is 80 cm s$^{-1}$ over 12 hours when averaged over all 300 APOGEE fibers and after removal of known trends and pressure correlations, implying the fiber etalon is intrinsically stable to significantly higher precision.

  5. VNIR, MWIR, and LWIR source assemblies for optical quality testing and spectro-radiometric calibration of earth observation satellites

    NASA Astrophysics Data System (ADS)

    Compain, Eric; Maquet, Philippe; Leblay, Pierrick; Gavaud, Eric; Marque, Julien; Glastre, Wilfried; Cortese, Maxime; Sugranes, Pierre; Gaillac, Stephanie; Potheau, Hervé

    2015-09-01

    This document presents several original OGSEs, Optical Ground Support Equipment, specifically designed and realized for the optical testing and calibration of earth observation satellites operating in a large spectral band from 0.4μm to 14.7μm. This work has been mainly supported by recent development dedicated to MTG, Meteosat Third Generation, the ESA next generation of meteorological satellites. The improved measurement capabilities of this new satellite generation has generated new challenging requirements for the associated optical test equipments. These improvements, based on design and component innovation will be illustrated for the MOTA, the GICS and the DEA OGSEs. MOTA and GICS are dedicated to the AIT, Assembly Integration and Test, of FCI, the Flexible Combined Imager of the imaging satellite MTG-I. DEA OGSE is dedicated to the AIT of the DEA, Detection Electronics Assembly, which is part of IRS instrument, an IR sounder part of MTG-S satellite. From an architectural point of view, the presented original designs enable to run many optical tests with a single system thanks to a limited configuration effort. Main measurement capabilities are optical quality testing (MTF based mainly on KEF measurement), Line of Sight (LoS) stability measurement, straylight analyses, VNIR-MWIR-LWIR focal plane array co-registration, and broadband large dynamic spectro-radiometric calibration. Depending on the AIT phase of the satellite, these source assemblies are operated at atmospheric pressure or under secondary vacuum. In operation, they are associated with an opto-mechanical projection system that enables to conjugate the image of the source assembly with the focal plane of the satellite instruments. These conjugation systems are usually based on high resolution, broadband collimator, and are optionally mounted on hexapod to address the entire field of instruments.

  6. Constrained Maximum Likelihood Estimation for Model Calibration Using Summary-level Information from External Big Data Sources.

    PubMed

    Chatterjee, Nilanjan; Chen, Yi-Hau; Maas, Paige; Carroll, Raymond J

    2016-03-01

    Information from various public and private data sources of extremely large sample sizes are now increasingly available for research purposes. Statistical methods are needed for utilizing information from such big data sources while analyzing data from individual studies that may collect more detailed information required for addressing specific hypotheses of interest. In this article, we consider the problem of building regression models based on individual-level data from an "internal" study while utilizing summary-level information, such as information on parameters for reduced models, from an "external" big data source. We identify a set of very general constraints that link internal and external models. These constraints are used to develop a framework for semiparametric maximum likelihood inference that allows the distribution of covariates to be estimated using either the internal sample or an external reference sample. We develop extensions for handling complex stratified sampling designs, such as case-control sampling, for the internal study. Asymptotic theory and variance estimators are developed for each case. We use simulation studies and a real data application to assess the performance of the proposed methods in contrast to the generalized regression (GR) calibration methodology that is popular in the sample survey literature.

  7. Constrained Maximum Likelihood Estimation for Model Calibration Using Summary-level Information from External Big Data Sources

    PubMed Central

    Chatterjee, Nilanjan; Chen, Yi-Hau; Maas, Paige; Carroll, Raymond J.

    2016-01-01

    Information from various public and private data sources of extremely large sample sizes are now increasingly available for research purposes. Statistical methods are needed for utilizing information from such big data sources while analyzing data from individual studies that may collect more detailed information required for addressing specific hypotheses of interest. In this article, we consider the problem of building regression models based on individual-level data from an “internal” study while utilizing summary-level information, such as information on parameters for reduced models, from an “external” big data source. We identify a set of very general constraints that link internal and external models. These constraints are used to develop a framework for semiparametric maximum likelihood inference that allows the distribution of covariates to be estimated using either the internal sample or an external reference sample. We develop extensions for handling complex stratified sampling designs, such as case-control sampling, for the internal study. Asymptotic theory and variance estimators are developed for each case. We use simulation studies and a real data application to assess the performance of the proposed methods in contrast to the generalized regression (GR) calibration methodology that is popular in the sample survey literature. PMID:27570323

  8. Apero, AN Open Source Bundle Adjusment Software for Automatic Calibration and Orientation of Set of Images

    NASA Astrophysics Data System (ADS)

    Pierrot Deseilligny, M.; Clery, I.

    2011-09-01

    IGN has developed a set of photogrammetric tools, APERO and MICMAC, for computing 3D models from set of images. This software, developed initially for its internal needs are now delivered as open source code. This paper focuses on the presentation of APERO the orientation software. Compared to some other free software initiatives, it is probably more complex but also more complete, its targeted user is rather professionals (architects, archaeologist, geomophologist) than people. APERO uses both computer vision approach for estimation of initial solution and photogrammetry for a rigorous compensation of the total error; it has a large library of parametric model of distortion allowing a precise modelization of all the kind of pinhole camera we know, including several model of fish-eye; there is also several tools for geo-referencing the result. The results are illustrated on various application, including the data-set of 3D-Arch workshop.

  9. Semi-quantitative and simulation analyses of effects of γ rays on determination of calibration factors of PET scanners with point-like (22)Na sources.

    PubMed

    Hasegawa, Tomoyuki; Sato, Yasushi; Oda, Keiichi; Wada, Yasuhiro; Murayama, Hideo; Yamada, Takahiro

    2011-09-21

    The uncertainty of radioactivity concentrations measured with positron emission tomography (PET) scanners ultimately depends on the uncertainty of the calibration factors. A new practical calibration scheme using point-like (22)Na radioactive sources has been developed. The purpose of this study is to theoretically investigate the effects of the associated 1.275 MeV γ rays on the calibration factors. The physical processes affecting the coincidence data were categorized in order to derive approximate semi-quantitative formulae. Assuming the design parameters of some typical commercial PET scanners, the effects of the γ rays as relative deviations in the calibration factors were evaluated by semi-quantitative formulae and a Monte Carlo simulation. The relative deviations in the calibration factors were less than 4%, depending on the details of the PET scanners. The event losses due to rejecting multiple coincidence events of scattered γ rays had the strongest effect. The results from the semi-quantitative formulae and the Monte Carlo simulation were consistent and were useful in understanding the underlying mechanisms. The deviations are considered small enough to correct on the basis of precise Monte Carlo simulation. This study thus offers an important theoretical basis for the validity of the calibration method using point-like (22)Na radioactive sources.

  10. Dosimetric characteristics, air-kerma strength calibration and verification of Monte Carlo simulation for a new ytterbium-169 brachytherapy source

    SciTech Connect

    Perera, H.; Williamson, J.F.; Li, Zuofeng; Mishra, V.; Meigooni, A.S. )

    1994-03-01

    Ytterbium-169 ([sup 169]Yb) is a promising new isotope for brachytherapy with a half life of 32 days and an average photon energy of 93 KeV. It has an Ir-192-equivalent dose distribution in water but a much smaller half-value layer in lead (0.2 mm), affording improved radiation protection and customized shielding of dose-limiting anatomic structures. The goals of this study are to: (a) experimentally validate Monte Carlo photon transport dose-rate calculations for this energy range, (b) to develop a secondary air-kerma strength standard for [sup 169]Yb, and (c) to present essential treatment planning data including the transverse-axis dose-rate distribution and dose correction factors for a number of local shielding materials. Several interstitial [sup 169]Yb sources (type 6) and an experimental high dose-rate source were made available for this study. Monte Carlo photon-transport (MCPT) simulations, based upon validated geometric models of source structure, were used to calculate dose rates in water. To verify MCPT predictions, the transverse-axis dose distribution in homogeneous water medium was measured using a silicon-diode detector. For use in designing shielded applicators, heterogeneity correction factors (HCF) arising from small cylindrical heterogeneities of lead, aluminum, titanium, steel and air were measured in a water medium. Finally, to provide a sound experimental basis for comparing experimental and theoretical dose-rate distributions, the air-kerma strength of the sources was measured using a calibrated ion chamber. To eliminate the influence of measurement artifacts on the comparison of theory and measurement, simulated detector readings were compared directly to measured diode readings. The final data are presented in the format endorsed by the Interstitial Collaborative Working Group. 33 refs., 8 figs., 3 tabs.

  11. Image Calibration

    NASA Technical Reports Server (NTRS)

    Peay, Christopher S.; Palacios, David M.

    2011-01-01

    Calibrate_Image calibrates images obtained from focal plane arrays so that the output image more accurately represents the observed scene. The function takes as input a degraded image along with a flat field image and a dark frame image produced by the focal plane array and outputs a corrected image. The three most prominent sources of image degradation are corrected for: dark current accumulation, gain non-uniformity across the focal plane array, and hot and/or dead pixels in the array. In the corrected output image the dark current is subtracted, the gain variation is equalized, and values for hot and dead pixels are estimated, using bicubic interpolation techniques.

  12. Calibration of microscopic traffic-flow models using multiple data sources.

    PubMed

    Hoogendoorn, Serge; Hoogendoorn, Raymond

    2010-10-13

    Parameter identification of microscopic driving models is a difficult task. This is caused by the fact that parameters--such as reaction time, sensitivity to stimuli, etc.--are generally not directly observable from common traffic data, but also due to the lack of reliable statistical estimation techniques. This contribution puts forward a new approach to identifying parameters of car-following models. One of the main contributions of this article is that the proposed approach allows for joint estimation of parameters using different data sources, including prior information on parameter values (or the valid range of values). This is achieved by generalizing the maximum-likelihood estimation approach proposed by the authors in previous work. The approach allows for statistical analysis of the parameter estimates, including the standard error of the parameter estimates and the correlation of the estimates. Using the likelihood-ratio test, models of different complexity (defined by the number of model parameters) can be cross-compared. A nice property of this test is that it takes into account the number of parameters of a model as well as the performance. To illustrate the workings, the approach is applied to two car-following models using vehicle trajectories of a Dutch freeway collected from a helicopter, in combination with data collected with a driving simulator.

  13. A practical implementation of the 2010 IPEM high dose rate brachytherapy code of practice for the calibration of 192Ir sources

    NASA Astrophysics Data System (ADS)

    Awunor, O. A.; Lecomber, A. R.; Richmond, N.; Walker, C.

    2011-08-01

    This paper details a practical method for deriving the reference air kerma rate calibration coefficient for Farmer NE2571 chambers using the UK Institute of Physics and Engineering in Medicine (IPEM) code of practice for the determination of the reference air kerma rate for HDR 192Ir brachytherapy sources based on the National Physical Laboratory (NPL) air kerma standard. The reference air kerma rate calibration coefficient was derived using pressure, temperature and source decay corrected ionization chamber response measurements over three successive 192Ir source clinical cycles. A secondary standard instrument (a Standard Imaging 1000 Plus well chamber) and four tertiary standard instruments (one additional Standard Imaging 1000 Plus well chamber and three Farmer NE2571 chambers housed in a perspex phantom) were used to provide traceability to the NPL primary standard and enable comparison of performance between the chambers. Conservative and optimized estimates on the expanded uncertainties (k = 2) associated with chamber response, ion recombination and reference air kerma rate calibration coefficient were determined. This was seen to be 2.3% and 0.4% respectively for chamber response, 0.2% and 0.08% respectively for ion recombination and 2.6% and 1.2% respectively for the calibration coefficient. No significant change in ion recombination with source decay was observed over the duration of clinical use of the respective 192Ir sources.

  14. A practical implementation of the 2010 IPEM high dose rate brachytherapy code of practice for the calibration of 192Ir sources.

    PubMed

    Awunor, O A; Lecomber, A R; Richmond, N; Walker, C

    2011-08-21

    This paper details a practical method for deriving the reference air kerma rate calibration coefficient for Farmer NE2571 chambers using the U.K. Institute of Physics and Engineering in Medicine (IPEM) code of practice for the determination of the reference air kerma rate for HDR (192)Ir brachytherapy sources based on the National Physical Laboratory (NPL) air kerma standard. The reference air kerma rate calibration coefficient was derived using pressure, temperature and source decay corrected ionization chamber response measurements over three successive (192)Ir source clinical cycles. A secondary standard instrument (a Standard Imaging 1000 Plus well chamber) and four tertiary standard instruments (one additional Standard Imaging 1000 Plus well chamber and three Farmer NE2571 chambers housed in a perspex phantom) were used to provide traceability to the NPL primary standard and enable comparison of performance between the chambers. Conservative and optimized estimates on the expanded uncertainties (k = 2) associated with chamber response, ion recombination and reference air kerma rate calibration coefficient were determined. This was seen to be 2.3% and 0.4% respectively for chamber response, 0.2% and 0.08% respectively for ion recombination and 2.6% and 1.2% respectively for the calibration coefficient. No significant change in ion recombination with source decay was observed over the duration of clinical use of the respective 192Ir sources.

  15. Korean VLBI Network Calibrator Survey (KVNCS). 1. Source Catalog of KVN Single-dish Flux Density Measurement in the K and Q Bands

    NASA Astrophysics Data System (ADS)

    Lee, Jeong Ae; Sohn, Bong Won; Jung, Taehyun; Byun, Do-Young; Lee, Jee Won

    2017-02-01

    We present the catalog of the KVN Calibrator Survey (KVNCS). This first part of the KVNCS is a single-dish radio survey simultaneously conducted at 22 (K band) and 43 GHz (Q band) using the Korean VLBI Network (KVN) from 2009 to 2011. A total of 2045 sources are selected from the VLBA Calibrator Survey with an extrapolated flux density limit of 100 mJy at the K band. The KVNCS contains 1533 sources in the K band with a flux density limit of 70 mJy and 553 sources in the Q band with a flux density limit of 120 mJy; it covers the whole sky down to ‑32.°5 in decl. We detected 513 sources simultaneously in the K and Q bands; ∼76% of them are flat-spectrum sources (‑0.5 ≤ α ≤ 0.5). From the flux–flux relationship, we anticipated that most of the radiation of many of the sources comes from the compact components. The sources listed in the KVNCS therefore are strong candidates for high-frequency VLBI calibrators.

  16. Broad-band calibration of marine seismic sources used by R/V Polarstern for academic research in polar regions

    NASA Astrophysics Data System (ADS)

    Breitzke, Monika; Boebel, Olaf; El Naggar, Saad; Jokat, Wilfried; Werner, Berthold

    2008-08-01

    Air guns and air-gun arrays of different volumes are used for scientific seismic surveys with R/V Polarstern in polar regions. To assess the potential risk of these research activities on marine mammal populations, knowledge of the sound pressure field of the seismic sources is essential. Therefore, a broad-band (0-80 kHz) calibration study was conducted at the Heggernes Acoustic Range, Norway. A GI (2.4 l), a G (8.5 l) and a Bolt gun (32.8 l) were deployed as single sources, 3 GI (7.4 l), 3 G (25.6 l) and 8 VLF™ Prakla-Seismos air guns (24.0 l) as arrays. Each configuration was fired along a line of 3-4 km length running between two hydrophone chains with receivers in 35, 100, 198 and 263 m depth. Peak-to-peak, zero-to-peak, rms and sound exposure levels (SEL) were analysed as functions of range. They show the typical dipole-like directivity of marine seismic sources with amplitude cancellation close to the sea surface, higher amplitudes in greater depths, and sound pressure levels which continuously decrease with range. Levels recorded during the approach are lower than during the departure indicating a shadowing effect of Polarsterns's hull. Backcalculated zero-to-peak source levels range from 224-240 dB re 1 μPa @ 1 m. Spectral source levels are highest below 100 Hz and amount to 182-194 dB re 1 μPa Hz-1. They drop off continuously with range and frequency. At 1 kHz they are ~30 dB, at 80 kHz ~60 dB lower than the peak level. Above 1 kHz amplitude spectra are dominated by Polarstern's self-noise. From the rms and sound exposure levels of the deepest hydrophone radii for different thresholds are derived. For a 180 dB rms-level threshold radii maximally vary between 200 and 600 m, for a 186 dB SEL threshold between 50 and 300 m.

  17. ESTIMATION OF NEUTRON SCATTER CORRECTION FOR CALIBRATION OF PERSONNEL DOSIMETER AND DOSERATEMETER AGAINST 241Am-Be SOURCE-MONTE CARLO SIMULATION AND MEASUREMENTS.

    PubMed

    Dawn, Sandipan; Bakshi, A K; Sathian, Deepa; Selvam, T Palani

    2016-10-07

    Neutron scatter contributions as a function of distance along the transverse axis of (241)Am-Be source were estimated by three different methods such as shadow cone, semi-empirical and Monte Carlo. The Monte Carlo-based FLUKA code was used to simulate the existing room used for the calibration of CR-39 detector as well as LB6411 doseratemeter for selected distances from (241)Am-Be source. The modified (241)Am-Be spectra at different irradiation geometries such as at different source detector distances, behind the shadow cone, at the surface of the water phantom were also evaluated using Monte Carlo calculations. Neutron scatter contributions, estimated using three different methods compare reasonably well. It is proposed to use the scattering correction factors estimated through Monte Carlo simulation and other methods for the calibration of CR-39 detector and doseratemeter at 0.75 and 1 m distance from the source.

  18. [Investigation of the present management status of calibration source based on the law concerning prevention of radiation hazards due to radioisotopes].

    PubMed

    Takahashi, Yasuyuki; Igarashi, Hiroshi; Hirano, Kunihiro; Kawaharada, Yasuhiro; Igarashi, Hitoshi; Murase, Ken-ya; Mochizuki, Teruhito

    2007-03-20

    An amendment concerning the enforcement of the law on the prevention of radiation hazards due to radioisotopes, etc., and the medical service law enforcement regulations were promulgated on June 1, 2005. This amendment concerned international basic safety standards and the sealing of radiation sources. Sealed radiation sources < or =3.7 MBq, which had been excluded from regulation, were newly included as an object of regulation. Investigation of the SPECT system instituted in hospitals indicated that almost all institutions adhere to the new amendment, and the calibration source, the checking source, etc., corresponding to this amendment were maintained appropriately. Any institutions planning to return sealed radioisotopes should refer to this report.

  19. Calibration of the WFC3 Emission-Line Filters and Application of the Results to the Greatest Source of Uncertainties in Determining Abundances in Gase

    NASA Astrophysics Data System (ADS)

    O'Dell, C.

    2010-09-01

    The WFC3 is arguably the most powerful camera that has been used on the HST. This capability arises in part from the uniquely complete set of narrow-band filters that were incorporated for making images of nebulae in emission-lines. Turning these oft-times beautiful images into scientifically useful information requires accurate flux calibration of the filters, which is the first subject of this proposal. The present plan is that WFC3 calibration will be done from pre-launch properties of the filters and observations of stars. The WFC3 filters transmission profiles were measured pre-launch in a different optical configuration and temperature than applies within the WFC3, thus rendering uncertain any flux calibrations tied to those pre-launch measurements. We propose to perform a ?ground-truth? calibration of the WFC3 narrow-band filters using NGC 6720 as a reference source, in much the same manner that the PI did when calibrating similar filters in the WFPC2 and the ACS.These new calibrations will then be used to address the t^2 problem in Gaseous Nebulae. This is the source of uncertainties in the relative abundances of factors 1.1 to 10 and undermines efforts to trace the abundance variations within our Galaxy and other galaxies. The t^2 problem remains unresolved after four decades and the NGC 6720 images used for the filter calibration may resolve the problem if they show that regions of small-scale temperature fluctuations arise from low-temperature shadow-zones behind knots that are known to exist within the nebula or from high-temperature shocks that have been posited. Unlike the case of the Orion Nebula, where we have addressed this problem with fewer diagnostic filters, the geometry of NGC 6720 is ideally favorable for seeing these temperature variations and identifying their cause.

  20. Estimating usual food intake distributions by using the multiple source method in the EPIC-Potsdam Calibration Study.

    PubMed

    Haubrock, Jennifer; Nöthlings, Ute; Volatier, Jean-Luc; Dekkers, Arnold; Ocké, Marga; Harttig, Ulrich; Illner, Anne-Kathrin; Knüppel, Sven; Andersen, Lene F; Boeing, Heiner

    2011-05-01

    Estimating usual food intake distributions from short-term quantitative measurements is critical when occasionally or rarely eaten food groups are considered. To overcome this challenge by statistical modeling, the Multiple Source Method (MSM) was developed in 2006. The MSM provides usual food intake distributions from individual short-term estimates by combining the probability and the amount of consumption with incorporation of covariates into the modeling part. Habitual consumption frequency information may be used in 2 ways: first, to distinguish true nonconsumers from occasional nonconsumers in short-term measurements and second, as a covariate in the statistical model. The MSM is therefore able to calculate estimates for occasional nonconsumers. External information on the proportion of nonconsumers of a food can also be handled by the MSM. As a proof-of-concept, we applied the MSM to a data set from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam Calibration Study (2004) comprising 393 participants who completed two 24-h dietary recalls and one FFQ. Usual intake distributions were estimated for 38 food groups with a proportion of nonconsumers > 70% in the 24-h dietary recalls. The intake estimates derived by the MSM corresponded with the observed values such as the group mean. This study shows that the MSM is a useful and applicable statistical technique to estimate usual food intake distributions, if at least 2 repeated measurements per participant are available, even for food groups with a sizeable percentage of nonconsumers.

  1. Mean-free-paths in concert and chamber music halls and the correct method for calibrating dodecahedral sound sources.

    PubMed

    Beranek, Leo L; Nishihara, Noriko

    2014-01-01

    The Eyring/Sabine equations assume that in a large irregular room a sound wave travels in straight lines from one surface to another, that the surfaces have an average sound absorption coefficient αav, and that the mean-free-path between reflections is 4 V/Stot where V is the volume of the room and Stot is the total area of all of its surfaces. No account is taken of diffusivity of the surfaces. The 4 V/Stot relation was originally based on experimental determinations made by Knudsen (Architectural Acoustics, 1932, pp. 132-141). This paper sets out to test the 4 V/Stot relation experimentally for a wide variety of unoccupied concert and chamber music halls with seating capacities from 200 to 5000, using the measured sound strengths Gmid and reverberation times RT60,mid. Computer simulations of the sound fields for nine of these rooms (of varying shapes) were also made to determine the mean-free-paths by that method. The study shows that 4 V/Stot is an acceptable relation for mean-free-paths in the Sabine/Eyring equations except for halls of unusual shape. Also demonstrated is the proper method for calibrating the dodecahedral sound source used for measuring the sound strength G, i.e., the reverberation chamber method.

  2. Multi-Objective vs. Single Objective Calibration of a Hydrologic Model using Either Different Hydrologic Signatures or Complementary Data Sources

    NASA Astrophysics Data System (ADS)

    Mai, J.; Cuntz, M.; Zink, M.; Schaefer, D.; Thober, S.; Samaniego, L. E.; Shafii, M.; Tolson, B.

    2015-12-01

    Hydrologic models are traditionally calibrated against discharge. Recent studies have shown however, that only a few global model parameters are constrained using the integral discharge measurements. It is therefore advisable to use additional information to calibrate those models. Snow pack data, for example, could improve the parametrization of snow-related processes, which might be underrepresented when using only discharge. One common approach is to combine these multiple objectives into one single objective function and allow the use of a single-objective algorithm. Another strategy is to consider the different objectives separately and apply a Pareto-optimizing algorithm. Both methods are challenging in the choice of appropriate multiple objectives with either conflicting interests or the focus on different model processes. A first aim of this study is to compare the two approaches employing the mesoscale Hydrologic Model mHM at several distinct river basins over Europe and North America. This comparison will allow the identification of the single-objective solution on the Pareto front. It is elucidated if this position is determined by the weighting and scaling of the multiple objectives when combing them to the single objective. The principal second aim is to guide the selection of proper objectives employing sensitivity analyses. These analyses are used to determine if an additional information would help to constrain additional model parameters. The additional information are either multiple data sources or multiple signatures of one measurement. It is evaluated if specific discharge signatures can inform different parts of the hydrologic model. The results show that an appropriate selection of discharge signatures increased the number of constrained parameters by more than 50% compared to using only NSE of the discharge time series. It is further assessed if the use of these signatures impose conflicting objectives on the hydrologic model. The usage of

  3. ORNL calibrations facility

    SciTech Connect

    Berger, C.D.; Gupton, E.D.; Lane, B.H.; Miller, J.H.; Nichols, S.W.

    1982-08-01

    The ORNL Calibrations Facility is operated by the Instrumentation Group of the Industrial Safety and Applied Health Physics Division. Its primary purpose is to maintain radiation calibration standards for calibration of ORNL health physics instruments and personnel dosimeters. This report includes a discussion of the radioactive sources and ancillary equipment in use and a step-by-step procedure for calibration of those survey instruments and personnel dosimeters in routine use at ORNL.

  4. The Use of Transfer Radiometers in Validating the Visible through Shortwave Infrared Calibrations of Radiance Sources Used by Instruments in NASA's Earth Observing System

    NASA Technical Reports Server (NTRS)

    Butler, James J.; Barnes, Robert A.

    2002-01-01

    The detection and study of climate change over a time frame of decades requires successive generations of satellite, airborne, and ground-based instrumentation carefully calibrated against a common radiance scale. In NASA s Earth Observing System (EOS) program, the pre-launch radiometric calibration of these instruments in the wavelength region from 400 nm to 2500 nm is accomplished using internally illuminated integrating spheres and diffuse reflectance panels illuminated by irradiance standard lamps. Since 1995, the EOS Calibration Program operating within the EOS Project Science Office (PSO) has enlisted the expertise of national standards laboratories and government and university metrology laboratories in an effort to validate the radiance scales assigned to sphere and panel radiance sources by EOS instrument calibration facilities. This state-of-the-art program has been accomplished using ultra-stable transfer radiometers independently calibrated by the above participating institutions. In ten comparisons since February 1995, the agreement between the radiance measurements of the transfer radiometers is plus or minus 1.80% at 411 nm, plus or minus 1.31% at 552.5 nm, plus or minus 1.32% at 868.0 nm, plus or minus 2.54% at 1622nm, and plus or minus 2.81% at 2200nm (sigma =1).

  5. Complementary b/y fragment ion pairs from post-source decay of metastable YahO for calibration of MALDI-TOF-TOF-MS/MS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Complementary b/y fragment ion pairs from post-source decay (PSD) of metastable YahO protein ion were evaluated for use in the calibration of MALDI-TOF-TOF for tandem mass spectrometry (MS/MS). The yahO gene from pathogenic Escherichia coli O157:H7 strain EDL933 was cloned into a pBAD18 plasmid vect...

  6. Real-time dynamic calibration of a tunable frequency laser source using a Fabry-Pérot interferometer

    SciTech Connect

    Mandula, Gábor Kis, Zsolt; Lengyel, Krisztián

    2015-12-15

    We report on a method for real-time dynamic calibration of a tunable external cavity diode laser by using a partially mode-matched plano-concave Fabry-Pérot interferometer in reflection geometry. Wide range laser frequency scanning is carried out by piezo-driven tilting of a diffractive grating playing the role of a frequency selective mirror in the laser cavity. The grating tilting system has a considerable mechanical inertness, so static laser frequency calibration leads to false results. The proposed real-time dynamic calibration based on the identification of primary- and Gouy-effect type secondary interference peaks with known frequency and temporal history can be used for a wide scanning range (from 0.2 GHz to more than 1 GHz). A concave spherical mirror with a radius of R = 100 cm and a plain 1% transmitting mirror was used as a Fabry-Pérot interferometer with various resonator lengths to investigate and demonstrate real-time calibration procedures for two kinds of laser frequency scanning functions.

  7. Calibration method for a photoacoustic system for real time source apportionment of light absorbing carbonaceous aerosol based on size distribution measurements

    NASA Astrophysics Data System (ADS)

    Utry, Noemi; Ajtai, Tibor; Pinter, Mate; Orvos, Peter I.; Szabo, Gabor; Bozoki, Zoltan

    2016-04-01

    In this study, we introduce a calibration method with which sources of light absorbing carbonaceous particulate matter (LAC) can be apportioned in real time based on multi wavelength optical absorption measurements with a photoacoustic system. The method is primary applicable in wintry urban conditions when LAC is dominated by traffic and biomass burning. The proposed method was successfully tested in a field campaign in the city center of Szeged, Hungary during winter time where the dominance of traffic and wood burning aerosol has been experimentally demonstrated earlier. With the help of the proposed calibration method a relationship between the measured Aerosol Angström Exponent (AAE) and the number size distribution can be deduced. Once the calibration curve is determined, the relative strength of the two pollution sources can be deduced in real time as long as the light absorbing fraction of PM is exclusively related to traffic and wood burning. This assumption is indirectly confirmed in the presented measurement campaign by the fact that the measured size distribution is composed of two unimodal size distributions identified to correspond to traffic and wood burning aerosols. The proposed method offers the possibility of replacing laborious chemical analysis with simple in-situ measurement of aerosol size distribution data.

  8. TA489A calibrator: SANDUS

    SciTech Connect

    LeBlanc, R.

    1987-08-01

    The TA489A Calibrator, designed to operate in the MA164 Digital Data Acquisition System, is used to calibrate up to 128 analog-to-digital recording channels. The TA489A calibrates using a dc Voltage Source or any of several special calibration modes. Calibration schemes are stored in the TA489A memory and are initiated locally or remotely through a Command Link.

  9. Radiance calibration of spherical integrators

    NASA Technical Reports Server (NTRS)

    Mclean, James T.; Guenther, Bruce W.

    1989-01-01

    Techniques for improving the knowledge of the radiance of large area spherical and hemispherical integrating energy sources have been investigated. Such sources are used to calibrate numerous aircraft and spacecraft remote sensing instruments. Comparisons are made between using a standard source based calibration method and a quantum efficient detector (QED) based calibration method. The uncertainty involved in transferring the calibrated values of the point source standard lamp to the extended source is estimated to be 5 to 10 percent. The use of the QED allows an improvement in the uncertainty to 1 to 2 percent for the measurement of absolute radiance from a spherical integrator source.

  10. Developing small vacuum spark as an x-ray source for calibration of an x-ray focusing crystal spectrometer.

    PubMed

    Ghomeishi, Mostafa; Karami, Mohammad; Adikan, Faisal Rafiq Mahamd

    2012-10-01

    A new technique of x-ray focusing crystal spectrometers' calibration is the desired result. For this purpose the spectrometer is designed to register radiated copper Kα and Kβ lines by using a flat α-quartz crystal. This experiment uses pre-breakdown x-ray emissions in low vacuum of about 2.5-3 mbar. At this pressure the pinch will not form so the plasma will not radiate. The anode material is copper and the capacity of the capacitor bank is 22.6 nF. This experiment designed and mounted a repetitive triggering system to save the operator time making hundreds of shots. This emission amount is good for calibration and geometrical adjustment of an optical crystal x-ray focusing spectrometer.

  11. Procedures for establishing and maintaining consistent air-kerma strength standards for low-energy, photon-emitting brachytherapy sources: recommendations of the Calibration Laboratory Accreditation Subcommittee of the American Association of Physicists in Medicine.

    PubMed

    DeWerd, Larry A; Huq, M Saiful; Das, Indra J; Ibbott, Geoffrey S; Hanson, William F; Slowey, Thomas W; Williamson, Jeffrey F; Coursey, Bert M

    2004-03-01

    Low dose rate brachytherapy is being used extensively for the treatment of prostate cancer. As of September 2003, there are a total of thirteen 125I and seven 103Pd sources that have calibrations from the National Institute of Standards and Technology (NIST) and the Accredited Dosimetry Calibration Laboratories (ADCLs) of the American Association of Physicists in Medicine (AAPM). The dosimetry standards for these sources are traceable to the NIST wide-angle free-air chamber. Procedures have been developed by the AAPM Calibration Laboratory Accreditation Subcommittee to standardize quality assurance and calibration, and to maintain the dosimetric traceability of these sources to ensure accurate clinical dosimetry. A description of these procedures is provided to the clinical users for traceability purposes as well as to provide guidance to the manufacturers of brachytherapy sources and ADCLs with regard to these procedures.

  12. Development and calibration of mirrors and gratings for the soft x-ray materials science beamline at the Linac Coherent Light Source free-electron laser.

    PubMed

    Soufli, Regina; Fernández-Perea, Mónica; Baker, Sherry L; Robinson, Jeff C; Gullikson, Eric M; Heimann, Philip; Yashchuk, Valeriy V; McKinney, Wayne R; Schlotter, William F; Rowen, Michael

    2012-04-20

    This work discusses the development and calibration of the x-ray reflective and diffractive elements for the Soft X-ray Materials Science (SXR) beamline of the Linac Coherent Light Source (LCLS) free-electron laser (FEL), designed for operation in the 500 to 2000 eV region. The surface topography of three Si mirror substrates and two Si diffraction grating substrates was examined by atomic force microscopy (AFM) and optical profilometry. The figure of the mirror substrates was also verified via surface slope measurements with a long trace profiler. A boron carbide (B4C) coating especially optimized for the LCLS FEL conditions was deposited on all SXR mirrors and gratings. Coating thickness uniformity of 0.14 nm root mean square (rms) across clear apertures extending to 205 mm length was demonstrated for all elements, as required to preserve the coherent wavefront of the LCLS source. The reflective performance of the mirrors and the diffraction efficiency of the gratings were calibrated at beamline 6.3.2 at the Advanced Light Source synchrotron. To verify the integrity of the nanometer-scale grating structure, the grating topography was examined by AFM before and after coating. This is to our knowledge the first time B4C-coated diffraction gratings are demonstrated for operation in the soft x-ray region.

  13. Development and calibration of mirrors and gratings for the Soft X-ray materials science beamline at the Linac Coherent Light Source free-electron laser

    SciTech Connect

    Soufli, Regina; Fernandez-Perea, Monica; Baker, Sherry L.; Robinson, Jeff C.; Gullikson, Eric M.; Heimann, Philip; Yashchuk, Valerie V.; McKinney, Wayne R.; Schlotter, William F.; Rowen, Michael

    2012-04-18

    This article discusses the development and calibration of the x-ray reflective and diffractive elements for the Soft X-ray Materials Science (SXR) beamline of the Linac Coherent Light Source (LCLS) free-electron laser (FEL), designed for operation in the 500 – 2000 eV region. The surface topography of three Si mirror substrates and two Si diffraction grating substrates was examined by atomic force microscopy (AFM) and optical profilometry. The figure of the mirror substrates was also verified via surface slope measurements with a long trace profiler. A boron carbide (B4C) coating especially optimized for the LCLS FEL conditions was deposited on all SXR mirrors and gratings. Coating thickness uniformity of 0.14 nm root mean square (rms) across clear apertures extending to 205 mm length was demonstrated for all elements, as required to preserve the coherent wavefront of the LCLS source. The reflective performance of the mirrors and the diffraction efficiency of the gratings were calibrated at beamline 6.3.2 at the Advanced Light Source synchrotron. To verify the integrity of the nanometer-scale grating structure, the grating topography was examined by AFM before and after coating. This is to our knowledge the first time B4C-coated diffraction gratings are demonstrated for operation in the soft x-ray region.

  14. Development and calibration of mirrors and gratings for the Soft X-ray materials science beamline at the Linac Coherent Light Source free-electron laser

    DOE PAGES

    Soufli, Regina; Fernandez-Perea, Monica; Baker, Sherry L.; ...

    2012-04-18

    This article discusses the development and calibration of the x-ray reflective and diffractive elements for the Soft X-ray Materials Science (SXR) beamline of the Linac Coherent Light Source (LCLS) free-electron laser (FEL), designed for operation in the 500 – 2000 eV region. The surface topography of three Si mirror substrates and two Si diffraction grating substrates was examined by atomic force microscopy (AFM) and optical profilometry. The figure of the mirror substrates was also verified via surface slope measurements with a long trace profiler. A boron carbide (B4C) coating especially optimized for the LCLS FEL conditions was deposited on allmore » SXR mirrors and gratings. Coating thickness uniformity of 0.14 nm root mean square (rms) across clear apertures extending to 205 mm length was demonstrated for all elements, as required to preserve the coherent wavefront of the LCLS source. The reflective performance of the mirrors and the diffraction efficiency of the gratings were calibrated at beamline 6.3.2 at the Advanced Light Source synchrotron. To verify the integrity of the nanometer-scale grating structure, the grating topography was examined by AFM before and after coating. This is to our knowledge the first time B4C-coated diffraction gratings are demonstrated for operation in the soft x-ray region.« less

  15. Calibrating R-LINE model results with observational data to develop annual mobile source air pollutant fields at fine spatial resolution: Application in Atlanta

    NASA Astrophysics Data System (ADS)

    Zhai, Xinxin; Russell, Armistead G.; Sampath, Poornima; Mulholland, James A.; Kim, Byeong-Uk; Kim, Yunhee; D'Onofrio, David

    2016-12-01

    The Research LINE-source (R-LINE) dispersion model for near-surface releases is a dispersion model developed to estimate the impacts of line sources, such as automobiles, on primary air pollutant levels. In a multiyear application in Atlanta, R-LINE simulations overestimated concentrations and spatial gradients compared to measurements. In this study we present a computationally efficient procedure for calculating annual average spatial fields and develop an approach for calibrating R-LINE concentrations with observational data. Simulated hourly concentrations of PM2.5, CO and NOx from mobile sources at 250 m resolution in the 20-county Atlanta area based on average diurnal emission profiles and meteorological categories were used to estimate annual averages. Compared to mobile source PM2.5 impacts estimated by chemical mass balance with gas constraints (CMB-GC), a source apportionment model based on PM2.5 speciation measurements, R-LINE estimates of traffic-generated PM2.5 impacts were found to be higher by a factor of 1.8 on average across all sites. Compared to observations of daily 1 h maximum CO and NOx, R-LINE estimates were higher by factors of 1.3 and 4.2 on average, respectively. Annual averages estimated by R-LINE were calibrated by regression with observations from 2002 to 2011 at multiple sites for daily 1 h maximum CO and NOx and with measurement-based mobile source impacts estimated by CMB-GC for PM2.5. The calibration reduced normalized mean bias (NMB) from 29% to 0.3% for PM2.5, from 22% to -1% for CO, and from 303% to 49% for NOx. Cross-validation analysis (withholding sites one at a time) leads to NMB of 13%, 1%, and 69% for PM2.5, CO, and NOx, respectively. The observation-calibrated R-LINE annual average spatial fields were compared with pollutant fields from observation-blended, 12 km resolution Community Multi-scale Air Quality (CMAQ) model fields for CO and NOx, with Pearson correlation R2 values of 0.55 for CO and 0.54 for NOx found. The

  16. Lifetime and Failure Characteristics of Pt/Ne Hollow Cathode Lamps Used as Calibration Sources for UV Space Instruments

    NASA Astrophysics Data System (ADS)

    Nave, Gillian; Sansonetti, Craig J.; Penton, Steven V.; Cunningham, Nathaniel; Beasley, Matthew; Osterman, Steven; Kerber, Florian; (Tony Keyes, Charles D.; Rosa, Michael R.

    2012-12-01

    We report accelerated aging tests on three Pt/Ne lamps from the same manufacturing run as lamps installed on the Cosmic Origins Spectrograph (COS). One lamp was aged in air at the National Institute of Standards and Technology (NIST) at a current of 10 mA and 50% duty cycle (30 s on, 30 s off) until failure. Two other lamps were aged by the COS instrument development team in a vacuum chamber. Initial radiometrically calibrated spectra were taken of all three lamps at NIST. Calibrated spectra of the air-aged lamp were taken after 206, 500, 778, 783 and 897 hr of operation. Spectra of the vacuum-aged lamps were taken after 500 hr for both lamps, and after 1000 hr for one of the lamps. During vacuum aging, the lamp voltage, photometric stability and temperature were monitored. All three lamps lasted for over 900 hr (100,000 cycles) when run at 10 mA, sufficient for 10–12 years of operation on COS. The total output dropped by less than 15% over 500 hr, with short-term repeatability within a few percent. We recommend that future space operation of these lamps include the lamp voltage in the telemetry as a diagnostic for the lamp aging.

  17. DIRBE External Calibrator (DEC)

    NASA Technical Reports Server (NTRS)

    Wyatt, Clair L.; Thurgood, V. Alan; Allred, Glenn D.

    1987-01-01

    Under NASA Contract No. NAS5-28185, the Center for Space Engineering at Utah State University has produced a calibration instrument for the Diffuse Infrared Background Experiment (DIRBE). DIRBE is one of the instruments aboard the Cosmic Background Experiment Observatory (COBE). The calibration instrument is referred to as the DEC (Dirbe External Calibrator). DEC produces a steerable, infrared beam of controlled spectral content and intensity and with selectable point source or diffuse source characteristics, that can be directed into the DIRBE to map fields and determine response characteristics. This report discusses the design of the DEC instrument, its operation and characteristics, and provides an analysis of the systems capabilities and performance.

  18. 10 CFR 32.102 - Schedule C-prototype tests for calibration or reference sources containing americium-241 or...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... sources containing americium-241 or radium-226. 32.102 Section 32.102 Energy NUCLEAR REGULATORY COMMISSION... americium-241 or radium-226. An applicant for a license under § 32.57 shall, for any type of source which is designed to contain more than 0.185 kilobecquerel (0.005 microcurie) of americium-241 or...

  19. 10 CFR 32.102 - Schedule C-prototype tests for calibration or reference sources containing americium-241 or...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... sources containing americium-241 or radium-226. 32.102 Section 32.102 Energy NUCLEAR REGULATORY COMMISSION... americium-241 or radium-226. An applicant for a license under § 32.57 shall, for any type of source which is designed to contain more than 0.185 kilobecquerel (0.005 microcurie) of americium-241 or...

  20. 10 CFR 32.102 - Schedule C-prototype tests for calibration or reference sources containing americium-241 or...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... sources containing americium-241 or radium-226. 32.102 Section 32.102 Energy NUCLEAR REGULATORY COMMISSION... americium-241 or radium-226. An applicant for a license under § 32.57 shall, for any type of source which is designed to contain more than 0.185 kilobecquerel (0.005 microcurie) of americium-241 or...

  1. 10 CFR 70.39 - Specific licenses for the manufacture or initial transfer of calibration or reference sources.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... radioactive material from the source shall be determined by measuring the radioactivity on the filter paper or by direct measurement of the radioactivity on the source following the dry wipe. (iii) Wet wipe test... be determined by measuring the radioactivity on the filter paper after it has dried or by...

  2. 10 CFR 70.39 - Specific licenses for the manufacture or initial transfer of calibration or reference sources.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... radioactive material from the source shall be determined by measuring the radioactivity on the filter paper or by direct measurement of the radioactivity on the source following the dry wipe. (iii) Wet wipe test... be determined by measuring the radioactivity on the filter paper after it has dried or by...

  3. 10 CFR 70.39 - Specific licenses for the manufacture or initial transfer of calibration or reference sources.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... radioactive material from the source shall be determined by measuring the radioactivity on the filter paper or by direct measurement of the radioactivity on the source following the dry wipe. (iii) Wet wipe test... be determined by measuring the radioactivity on the filter paper after it has dried or by...

  4. 10 CFR 70.39 - Specific licenses for the manufacture or initial transfer of calibration or reference sources.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... radioactive material from the source shall be determined by measuring the radioactivity on the filter paper or by direct measurement of the radioactivity on the source following the dry wipe. (iii) Wet wipe test... be determined by measuring the radioactivity on the filter paper after it has dried or by...

  5. 10 CFR 70.39 - Specific licenses for the manufacture or initial transfer of calibration or reference sources.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... radioactive material from the source shall be determined by measuring the radioactivity on the filter paper or by direct measurement of the radioactivity on the source following the dry wipe. (iii) Wet wipe test... be determined by measuring the radioactivity on the filter paper after it has dried or by...

  6. Comparison of a Joule effect calibration system using Kanthal wire and a laser diode as heat sources

    NASA Astrophysics Data System (ADS)

    Maldonado, Blas A.; Bárcena-Soto, Maximiliano; Casillas, Norberto; Flores, Jorge L.

    2009-09-01

    Here it is presented a comparison of two calibration techniques applied to a thermistor element used in a surface microcalorimeter which operates under Isoperibol conditions. Usually surface microcalorimeters employ a thermistor as a temperature sensing element, whose heat capacity requires to be evaluated before they can be used. One alternative method to estimate its heat capacity is by supplying a known amount of energy and detecting its temperature changes. Thus, surface heating can be achieved by different techniques; one of them is by supplying energy to the thermistor by passing current through a Ni-Cr coil wined around the glass bulb thermistor. A rather different and more convenient technique consists of directly illuminating a small well-defined thermistor area with an infrared 1550 nm wavelength laser beam, while detecting the thermistor temperature changes. Both procedures are thoroughly compared and the heat capacities obtained by both methods are presented.

  7. The calibration of read-out-streak photometry in the XMM-Newton Optical Monitor and the construction of a bright-source catalogue

    NASA Astrophysics Data System (ADS)

    Page, M. J.; Chan, N.; Breeveld, A. A.; Talavera, A.; Yershov, V.; Kennedy, T.; Kuin, N. P. M.; Hancock, B.; Smith, P. J.; Carter, M.

    2017-04-01

    The dynamic range of the XMM-Newton Optical Monitor (XMM-OM) is limited at the bright end by coincidence loss, the superposition of multiple photons in the individual frames recorded from its micro-channel-plate (MCP) intensified charge-coupled device (CCD) detector. One way to overcome this limitation is to use photons that arrive during the frame transfer of the CCD, forming vertical read-out streaks for bright sources. We calibrate these read-out streaks for photometry of bright sources observed with XMM-OM. The bright-source limit for read-out-streak photometry is set by the recharge time of the MCPs. For XMM-OM, we find that the MCP recharge time is 5.5 × 10-4 s. We determine that the effective bright limits for read-out-streak photometry with XMM-OM are approximately 1.5 mag brighter than the bright-source limits for normal aperture photometry in full-frame images. This translates into bright-source limits in Vega magnitudes of UVW2=7.1, UVM2=8.0, UVW1=9.4, U=10.5, B=11.5, V=10.2, and White=12.5 for data taken early in the mission. The limits brighten by up to 0.2 mag, depending on filter, over the course of the mission as the detector ages. The method is demonstrated by deriving UVW1 photometry for the symbiotic nova RR Telescopii, and the new photometry is used to constrain the e-folding time of its decaying ultraviolet (UV) emission. Using the read-out-streak method, we obtain photometry for 50 per cent of the missing UV source measurements in version 2.1 of the XMM-Newton Serendipitous UV Source Survey catalogue.

  8. Optical detector calibrator system

    NASA Technical Reports Server (NTRS)

    Strobel, James P. (Inventor); Moerk, John S. (Inventor); Youngquist, Robert C. (Inventor)

    1996-01-01

    An optical detector calibrator system simulates a source of optical radiation to which a detector to be calibrated is responsive. A light source selected to emit radiation in a range of wavelengths corresponding to the spectral signature of the source is disposed within a housing containing a microprocessor for controlling the light source and other system elements. An adjustable iris and a multiple aperture filter wheel are provided for controlling the intensity of radiation emitted from the housing by the light source to adjust the simulated distance between the light source and the detector to be calibrated. The geared iris has an aperture whose size is adjustable by means of a first stepper motor controlled by the microprocessor. The multiple aperture filter wheel contains neutral density filters of different attenuation levels which are selectively positioned in the path of the emitted radiation by a second stepper motor that is also controlled by the microprocessor. An operator can select a number of detector tests including range, maximum and minimum sensitivity, and basic functionality. During the range test, the geared iris and filter wheel are repeatedly adjusted by the microprocessor as necessary to simulate an incrementally increasing simulated source distance. A light source calibration subsystem is incorporated in the system which insures that the intensity of the light source is maintained at a constant level over time.

  9. Spectral responsivity calibration of the reference radiation thermometer at KRISS by using a super-continuum laser-based high-accuracy monochromatic source

    NASA Astrophysics Data System (ADS)

    Yoo, Yong Shim; Kim, Gun Jung; Park, Seongchong; Lee, Dong-Hoon; Kim, Bong-Hak

    2016-12-01

    We report on the calibration of the relative spectral responsivity of the reference radiation thermometer, model LP4, which is used for the experimental realisation of the international temperature scale of 1990 above 960 °C at the Korea Research Institute of Standards and Science. The relative spectral responsivity of LP4 is measured by using a monochromatic source consisting of a super-continuum laser and a double-grating monochromator. By monitoring the wavelength of the output beam directly with a calibrated wavelength-meter, we achieved a high-accuracy measurement of spectral responsivity with a maximum wavelength error of less than 3 pm, a narrow spectral bandwidth of less than 0.4 nm, and a high dynamic range over 8 decades. We evaluated the contributions of various uncertainty components of the spectral responsivity measurement to the uncertainty of the temperature scale based on a practical estimation approach, which numerically calculates the maximal effects of the variations of each component. As a result, we evaluate the uncertainty contribution from the spectral responsivity measurement to the temperature scale to be less than 64 mK (k  =  1) in a range from 660 °C to 2749 °C for the LP4 with a filter at 650 nm.

  10. Application of a superoxide (O(2)(-)) thermal source (SOTS-1) for the determination and calibration of O(2)(-) fluxes in seawater.

    PubMed

    Heller, M I; Croot, P L

    2010-05-14

    Superoxide (O(2)(-)) is an important short lived transient reactive oxygen species (ROS) in seawater. The main source of O(2)(-) in the ocean is believed to be through photochemical reactions though biological processes may also be important. Sink terms for O(2)(-) include redox reactions with bioactive trace metals, including Cu and Fe, and to a lesser extent dissolved organic matter (DOM). Information on the source fluxes, sinks and concentration of superoxide in the open ocean are crucial to improving our understanding of the biogeochemical cycling of redox active species. As O(2)(-) is a highly reactive transient species present at low concentrations it is not a trivial task to make accurate and precise measurements in seawater. In this study we developed the appropriate numerical analysis tools and investigated a number of superoxide sources and methods for the purposes of calibrating O(2)(-) concentrations and/or fluxes specifically in seawater. We found the superoxide thermal source bis(4-carboxybenzyl)hyponitrite (SOTS)-1 easy to employ as a reliable source of O(2)(-) which could be successfully applied in seawater. The thermal decomposition of SOTS-1 in seawater was evaluated over a range of seawater temperatures using both a flux based detection scheme developed using two spectrophotometric methods: (i) 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) and (ii) ferricytochrome c (FC), or a concentration based detection scheme using a chemiluminescence flow injection method based on the Cypridina luciferin analog 2-methyl-6-(p-methoxyphenyl)3-7-dihydroimidazol[1,2-alpha]pyrazin-3-one (MCLA) as reagent. Our results suggest SOTS-1 is the best available O(2)(-) source for determining concentrations and fluxes, all detection systems tested have their pros and cons and the choice of which to use depends more on the duration and type of experiment that is required.

  11. Calibration and operational data for a compact photodiode detector useful for monitoring the location of moving sources of positron emitting radioisotopes

    NASA Astrophysics Data System (ADS)

    Marsland, M. G.; Dehnel, M. P.; Johansson, S.; Rajander, J.; Solin, O.; Theroux, J.; Stewart, T. M.; Christensen, T.; Hollinger, C.

    2013-04-01

    D-Pace has developed a compact cost-effective gamma detector system based on technology licensed from TRIUMF [1]. These photodiode detectors are convenient for detecting the presence of positron emitting radioisotopes, particularly for the case of transport of radioisotopes from a PET cyclotron to hotlab, or from one location to another in an automated radiochemistry processing unit. This paper describes recent calibration experiments undertaken at the Turku PET Centre for stationary and moving sources of F18 and C11 in standard setups. The practical diagnostic utility of using several of these devices to track the transport of radioisotopes from the cyclotron to hotlab is illustrated. For example, such a detector system provides: a semi-quantitative indication of total activity, speed of transport, location of any activity lost en route and effectiveness of follow-up system flushes, a means of identifying bolus break-up, feedback useful for deciding when to change out tubing.

  12. Calibration and operational data for a compact photodiode detector useful for monitoring the location of moving sources of positron emitting radioisotopes

    SciTech Connect

    Marsland, M. G.; Dehnel, M. P.; Theroux, J.; Christensen, T.; Hollinger, C.; Johansson, S.; Rajander, J.; Solin, O.; Stewart, T. M.

    2013-04-19

    D-Pace has developed a compact cost-effective gamma detector system based on technology licensed from TRIUMF. These photodiode detectors are convenient for detecting the presence of positron emitting radioisotopes, particularly for the case of transport of radioisotopes from a PET cyclotron to hotlab, or from one location to another in an automated radiochemistry processing unit. This paper describes recent calibration experiments undertaken at the Turku PET Centre for stationary and moving sources of F18 and C11 in standard setups. The practical diagnostic utility of using several of these devices to track the transport of radioisotopes from the cyclotron to hotlab is illustrated. For example, such a detector system provides: a semi-quantitative indication of total activity, speed of transport, location of any activity lost en route and effectiveness of follow-up system flushes, a means of identifying bolus break-up, feedback useful for deciding when to change out tubing.

  13. Selection of the appropriate radionuclide source for the efficiency calibration in methods of determining gross alpha activity in water.

    PubMed

    Corbacho, J A; Zapata-García, D; Montaña, M; Fons, J; Camacho, A; Guillén, J; Serrano, I; Baeza, A; Llauradó, M; Vallés, I

    2016-01-01

    Measuring the gross alpha activity in water samples is a rapid, straightforward way of determining whether the water might contain a radionuclide concentration whose consumption would imply a total indicative dose (TID) greater than some reference limit - currently set at 0.1 mSv/y in Europe. There are several methods used for such measurements. Two of them are desiccation with the salts being deposited on a planchet, and coprecipitation. The main advantage of these two methods is their ease of implementation and low cost of preparing the source to measure. However, there is considerable variability in the selection of the most suitable radioactive reference standard against which to calculate the water's gross alpha activity. The goal of this paper is to propose the most appropriate reference radionuclides to use as standards in determining gross alpha activities with these two methods, taking into account the natural radioactive characteristics of a wide range of waters collected at different points in Spain. Thus, the results will be consistent with each other and representative of the sum of alpha activities of all the alpha-emitters contained in a sample.

  14. A variable acceleration calibration system

    NASA Astrophysics Data System (ADS)

    Johnson, Thomas H.

    2011-12-01

    A variable acceleration calibration system that applies loads using gravitational and centripetal acceleration serves as an alternative, efficient and cost effective method for calibrating internal wind tunnel force balances. Two proof-of-concept variable acceleration calibration systems are designed, fabricated and tested. The NASA UT-36 force balance served as the test balance for the calibration experiments. The variable acceleration calibration systems are shown to be capable of performing three component calibration experiments with an approximate applied load error on the order of 1% of the full scale calibration loads. Sources of error are indentified using experimental design methods and a propagation of uncertainty analysis. Three types of uncertainty are indentified for the systems and are attributed to prediction error, calibration error and pure error. Angular velocity uncertainty is shown to be the largest indentified source of prediction error. The calibration uncertainties using a production variable acceleration based system are shown to be potentially equivalent to current methods. The production quality system can be realized using lighter materials and a more precise instrumentation. Further research is needed to account for balance deflection, forcing effects due to vibration, and large tare loads. A gyroscope measurement technique is shown to be capable of resolving the balance deflection angle calculation. Long term research objectives include a demonstration of a six degree of freedom calibration, and a large capacity balance calibration.

  15. Self-Calibrating Pressure Transducer

    NASA Technical Reports Server (NTRS)

    Lueck, Dale E. (Inventor)

    2006-01-01

    A self-calibrating pressure transducer is disclosed. The device uses an embedded zirconia membrane which pumps a determined quantity of oxygen into the device. The associated pressure can be determined, and thus, the transducer pressure readings can be calibrated. The zirconia membrane obtains oxygen .from the surrounding environment when possible. Otherwise, an oxygen reservoir or other source is utilized. In another embodiment, a reversible fuel cell assembly is used to pump oxygen and hydrogen into the system. Since a known amount of gas is pumped across the cell, the pressure produced can be determined, and thus, the device can be calibrated. An isolation valve system is used to allow the device to be calibrated in situ. Calibration is optionally automated so that calibration can be continuously monitored. The device is preferably a fully integrated MEMS device. Since the device can be calibrated without removing it from the process, reductions in costs and down time are realized.

  16. Anemometer calibrator

    NASA Technical Reports Server (NTRS)

    Bate, T.; Calkins, D. E.; Price, P.; Veikins, O.

    1971-01-01

    Calibrator generates accurate flow velocities over wide range of gas pressure, temperature, and composition. Both pressure and flow velocity can be maintained within 0.25 percent. Instrument is essentially closed loop hydraulic system containing positive displacement drive.

  17. Study of the influence of heat sources on the out-of-pile calibration curve of calorimetric cells used for nuclear energy deposition quantification

    SciTech Connect

    De Vita, C.; Brun, J.; Reynard-Carette, C.; Carette, M.; Amharrak, H.; Lyoussi, A.; Fourmentel, D.; Villard, J.F.

    2015-07-01

    calorimeter cell head. This discrepancy is higher than in previous experiments because the calorimeter owns a high sensitivity. Consequently, a new prototype was created and instrumented by other heat sources in order to impose an energy deposition on the calorimetric cell structure (in particular in the base) and to improve the calibration step in out-of-pile conditions. In this paper, on the first part a detailed description of the new calorimetric sensor will be given. On the second part, the experimental response of the sensor obtained for several internal heating conditions will be shown. The influence of these conditions on the calibration curve will be discussed. Then the response of this prototype will be also presented for different external cooling fluid conditions (in particular flow temperature). In this part, the comparison between the in-pile and out-of-pile experimental results will be performed. On the last part, these out-of-pile experiments will be completed by 2D axisymmetrical thermal simulations with the CEA code CAST3M using Finite Elements Method. After a comparison between experimental and numerical works, improvements of the sensor prototype will be studied (new heat sources). (authors)

  18. GTC Photometric Calibration

    NASA Astrophysics Data System (ADS)

    di Cesare, M. A.; Hammersley, P. L.; Rodriguez Espinosa, J. M.

    2006-06-01

    We are currently developing the calibration programme for GTC using techniques similar to the ones use for the space telescope calibration (Hammersley et al. 1998, A&AS, 128, 207; Cohen et al. 1999, AJ, 117, 1864). We are planning to produce a catalogue with calibration stars which are suitable for a 10-m telescope. These sources will be not variable, non binary and do not have infrared excesses if they are to be used in the infrared. The GTC science instruments require photometric calibration between 0.35 and 2.5 microns. The instruments are: OSIRIS (Optical System for Imaging low Resolution Integrated Spectroscopy), ELMER and EMIR (Espectrógrafo Multiobjeto Infrarrojo) and the Acquisition and Guiding boxes (Di Césare, Hammersley, & Rodriguez Espinosa 2005, RevMexAA Ser. Conf., 24, 231). The catalogue will consist of 30 star fields distributed in all of North Hemisphere. We will use fields containing sources over the range 12 to 22 magnitude, and spanning a wide range of spectral types (A to M) for the visible and near infrared. In the poster we will show the method used for selecting these fields and we will present the analysis of the data on the first calibration fields observed.

  19. 10 CFR 35.61 - Calibration of survey instruments.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... repair that affects the calibration. A licensee shall— (1) Calibrate all scales with readings up to 10 mSv (1000 mrem) per hour with a radiation source; (2) Calibrate two separated readings on each...

  20. 10 CFR 35.61 - Calibration of survey instruments.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... repair that affects the calibration. A licensee shall— (1) Calibrate all scales with readings up to 10 mSv (1000 mrem) per hour with a radiation source; (2) Calibrate two separated readings on each...

  1. 10 CFR 35.61 - Calibration of survey instruments.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... repair that affects the calibration. A licensee shall— (1) Calibrate all scales with readings up to 10 mSv (1000 mrem) per hour with a radiation source; (2) Calibrate two separated readings on each...

  2. Calibration Techniques

    NASA Astrophysics Data System (ADS)

    Wurz, Peter; Balogh, Andre; Coffey, Victoria; Dichter, Bronislaw K.; Kasprzak, Wayne T.; Lazarus, Alan J.; Lennartsson, Walter; McFadden, James P.

    Calibration and characterization of particle instruments with supporting flight electronics is necessary for the correct interpretation of the returned data. Generally speaking, the instrument will always return a measurement value (typically in form of a digital number), for example a count rate, for the measurement of an external quantity, which could be an ambient neutral gas density, an ion composition (species measured and amount), or electron density. The returned values are used then to derive parameters associated with the distribution such as temperature, bulk flow speed, differential energy flux and others. With the calibration of the instrument the direct relationship between the external quantity and the returned measurement value has to be established so that the data recorded during flight can be correctly interpreted. While calibration and characterization of an instrument are usually done in ground-based laboratories prior to integration of the instrument in the spacecraft, it can also be done in space.

  3. [Laser-based radiometric calibration].

    PubMed

    Li, Zhi-gang; Zheng, Yu-quan

    2014-12-01

    Increasingly higher demands are put forward to spectral radiometric calibration accuracy and the development of new tunable laser based spectral radiometric calibration technology is promoted, along with the development of studies of terrestrial remote sensing, aeronautical and astronautical remote sensing, plasma physics, quantitative spectroscopy, etc. Internationally a number of national metrology scientific research institutes have built tunable laser based spectral radiometric calibration facilities in succession, which are traceable to cryogenic radiometers and have low uncertainties for spectral responsivity calibration and characterization of detectors and remote sensing instruments in the UK, the USA, Germany, etc. Among them, the facility for spectral irradiance and radiance responsivity calibrations using uniform sources (SIRCCUS) at the National Institute of Standards and Technology (NIST) in the USA and the Tunable Lasers in Photometry (TULIP) facility at the Physikalisch-Technische Bundesanstalt (PTB) in Germany have more representatives. Compared with lamp-monochromator systems, laser based spectral radiometric calibrations have many advantages, such as narrow spectral bandwidth, high wavelength accuracy, low calibration uncertainty and so on for radiometric calibration applications. In this paper, the development of laser-based spectral radiometric calibration and structures and performances of laser-based radiometric calibration facilities represented by the National Physical Laboratory (NPL) in the UK, NIST and PTB are presented, technical advantages of laser-based spectral radiometric calibration are analyzed, and applications of this technology are further discussed. Laser-based spectral radiometric calibration facilities can be widely used in important system-level radiometric calibration measurements with high accuracy, including radiance temperature, radiance and irradiance calibrations for space remote sensing instruments, and promote the

  4. Recent Infrasound Calibration Activity at Los Alamos

    NASA Astrophysics Data System (ADS)

    Whitaker, R. W.; Marcillo, O. E.

    2014-12-01

    Absolute infrasound sensor calibration is necessary for estimating source sizes from measured waveforms. This can be an important function in treaty monitoring. The Los Alamos infrasound calibration chamber is capable of absolute calibration. Early in 2014 the Los Alamos infrasound calibration chamber resumed operations in its new location after an unplanned move two years earlier. The chamber has two sources of calibration signals. The first is the original mechanical piston, and the second is a CLD Dynamics Model 316 electro-mechanical unit that can be digitally controlled and provide a richer set of calibration options. During 2008-2010 a number of upgrades were incorporated for improved operation and recording. In this poster we give an overview of recent chamber work on sensor calibrations, calibration with the CLD unit, some measurements with different porous hoses and work with impulse sources.

  5. BATSE spectroscopy detector calibration

    NASA Technical Reports Server (NTRS)

    Band, D.; Ford, L.; Matteson, J.; Lestrade, J. P.; Teegarden, B.; Schaefer, B.; Cline, T.; Briggs, M.; Paciesas, W.; Pendleton, G.

    1992-01-01

    We describe the channel-to-energy calibration of the Spectroscopy Detectors of the Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory (GRO). These detectors consist of NaI(TI) crystals viewed by photomultiplier tubes whose output in turn is measured by a pulse height analyzer. The calibration of these detectors has been complicated by frequent gain changes and by nonlinearities specific to the BATSE detectors. Nonlinearities in the light output from the NaI crystal and in the pulse height analyzer are shifted relative to each other by changes in the gain of the photomultiplier tube. We present the analytical model which is the basis of our calibration methodology, and outline how the empirical coefficients in this approach were determined. We also describe the complications peculiar to the Spectroscopy Detectors, and how our understanding of the detectors' operation led us to a solution to these problems.

  6. FlowCal: A User-Friendly, Open Source Software Tool for Automatically Converting Flow Cytometry Data from Arbitrary to Calibrated Units.

    PubMed

    Castillo-Hair, Sebastian M; Sexton, John T; Landry, Brian P; Olson, Evan J; Igoshin, Oleg A; Tabor, Jeffrey J

    2016-07-15

    Flow cytometry is widely used to measure gene expression and other molecular biological processes with single cell resolution via fluorescent probes. Flow cytometers output data in arbitrary units (a.u.) that vary with the probe, instrument, and settings. Arbitrary units can be converted to the calibrated unit molecules of equivalent fluorophore (MEF) using commercially available calibration particles. However, there is no convenient, nonproprietary tool available to perform this calibration. Consequently, most researchers report data in a.u., limiting interpretation. Here, we report a software tool named FlowCal to overcome current limitations. FlowCal can be run using an intuitive Microsoft Excel interface, or customizable Python scripts. The software accepts Flow Cytometry Standard (FCS) files as inputs and is compatible with different calibration particles, fluorescent probes, and cell types. Additionally, FlowCal automatically gates data, calculates common statistics, and produces publication quality plots. We validate FlowCal by calibrating a.u. measurements of E. coli expressing superfolder GFP (sfGFP) collected at 10 different detector sensitivity (gain) settings to a single MEF value. Additionally, we reduce day-to-day variability in replicate E. coli sfGFP expression measurements due to instrument drift by 33%, and calibrate S. cerevisiae Venus expression data to MEF units. Finally, we demonstrate a simple method for using FlowCal to calibrate fluorescence units across different cytometers. FlowCal should ease the quantitative analysis of flow cytometry data within and across laboratories and facilitate the adoption of standard fluorescence units in synthetic biology and beyond.

  7. SNLS calibrations

    NASA Astrophysics Data System (ADS)

    Regnault, N.

    2015-08-01

    The Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) is a massive imaging survey, conducted between 2003 and 2008, with the MegaCam instrument, mounted on the CFHT-3.6-m telescope. With a 1 degree wide focal plane, made of 36 2048 × 4612 sensors totalling 340 megapixels, MegaCam was at the time the largest imager on the sky. The Supernova Legacy Survey (SNLS) uses the cadenced observations of the 4 deg2 wide "DEEP" layer of the CFHTLS to search and follow-up Type Ia supernovae (SNe Ia) and study the acceleration of the cosmic expansion. The reduction and calibration of the CFHTLS/SNLS datasets has posed a series of challenges. In what follows, we give a brief account of the photometric calibration work that has been performed on the SNLS data over the last decade.

  8. Variation in the calibrated response of LiF, Al2O3, and silicon dosimeters when used for in-phantom measurements of source photons with energies between 30 KeV AND 300 KeV.

    PubMed

    Poudel, Sashi; Currier, Blake; Medich, David C

    2015-04-01

    The MCNP5 radiation transport code was used to quantify changes in the absorbed dose conversion factor for LiF, Al2O3, and silicon-based electronic dosimeters calibrated in-air using standard techniques and summarily used to measure absorbed dose to water when placed in a water phantom. A mono-energetic photon source was modeled at energies between 30 keV and 300 keV for a point-source placed at the center of a water phantom, a point-source placed at the surface of the phantom, and for a 10-cm radial field geometry. Dosimetric calculations were obtained for water, LiF, Al2O3, and silicon at depths of 0.2 cm and 10 cm from the source. These results were achieved using the MCNP5 *FMESH photon energy-fluence tally, which was coupled with the appropriate DE/DF card for each dosimetric material studied to convert energy-fluence into the absorbed dose. The dosimeter's absorbed dose conversion factor was calculated as a ratio of the absorbed dose to water to that of the dosimeter measured at a specified phantom depth. The dosimeter's calibration value also was obtained. Based on these results, the absorbed dose conversion factor for a LiF dosimeter was found to deviate from its calibration value by up to 9%, an Al2O3 dosimeter by 43%, and a silicon dosimeter by 61%. These data therefore can be used to obtain LiF, Al2O3, and silicon dosimeter correction factors for mono-energetic and poly-energetic sources at measurement depths up to 10 cm under the irradiation geometries investigated herein.

  9. The Advanced LIGO photon calibrators

    NASA Astrophysics Data System (ADS)

    Karki, S.; Tuyenbayev, D.; Kandhasamy, S.; Abbott, B. P.; Abbott, T. D.; Anders, E. H.; Berliner, J.; Betzwieser, J.; Cahillane, C.; Canete, L.; Conley, C.; Daveloza, H. P.; De Lillo, N.; Gleason, J. R.; Goetz, E.; Izumi, K.; Kissel, J. S.; Mendell, G.; Quetschke, V.; Rodruck, M.; Sachdev, S.; Sadecki, T.; Schwinberg, P. B.; Sottile, A.; Wade, M.; Weinstein, A. J.; West, M.; Savage, R. L.

    2016-11-01

    The two interferometers of the Laser Interferometry Gravitational-wave Observatory (LIGO) recently detected gravitational waves from the mergers of binary black hole systems. Accurate calibration of the output of these detectors was crucial for the observation of these events and the extraction of parameters of the sources. The principal tools used to calibrate the responses of the second-generation (Advanced) LIGO detectors to gravitational waves are systems based on radiation pressure and referred to as photon calibrators. These systems, which were completely redesigned for Advanced LIGO, include several significant upgrades that enable them to meet the calibration requirements of second-generation gravitational wave detectors in the new era of gravitational-wave astronomy. We report on the design, implementation, and operation of these Advanced LIGO photon calibrators that are currently providing fiducial displacements on the order of 1 0-18m /√{Hz } with accuracy and precision of better than 1%.

  10. ALTEA calibration

    NASA Astrophysics Data System (ADS)

    Zaconte, V.; Altea Team

    The ALTEA project is aimed at studying the possible functional damages to the Central Nervous System (CNS) due to particle radiation in space environment. The project is an international and multi-disciplinary collaboration. The ALTEA facility is an helmet-shaped device that will study concurrently the passage of cosmic radiation through the brain, the functional status of the visual system and the electrophysiological dynamics of the cortical activity. The basic instrumentation is composed by six active particle telescopes, one ElectroEncephaloGraph (EEG), a visual stimulator and a pushbutton. The telescopes are able to detect the passage of each particle measuring its energy, trajectory and released energy into the brain and identifying nuclear species. The EEG and the Visual Stimulator are able to measure the functional status of the visual system, the cortical electrophysiological activity, and to look for a correlation between incident particles, brain activity and Light Flash perceptions. These basic instruments can be used separately or in any combination, permitting several different experiments. ALTEA is scheduled to fly in the International Space Station (ISS) in November, 15th 2004. In this paper the calibration of the Flight Model of the silicon telescopes (Silicon Detector Units - SDUs) will be shown. These measures have been taken at the GSI heavy ion accelerator in Darmstadt. First calibration has been taken out in November 2003 on the SDU-FM1 using C nuclei at different energies: 100, 150, 400 and 600 Mev/n. We performed a complete beam scan of the SDU-FM1 to check functionality and homogeneity of all strips of silicon detector planes, for each beam energy we collected data to achieve good statistics and finally we put two different thickness of Aluminium and Plexiglas in front of the detector in order to study fragmentations. This test has been carried out with a Test Equipment to simulate the Digital Acquisition Unit (DAU). We are scheduled to

  11. Radiometric absolute noise-temperature measurement system features improved accuracy and calibration ease

    NASA Technical Reports Server (NTRS)

    Brown, W.; Ewen, H.; Haroules, G.

    1970-01-01

    Radiometric receiver system, which measures noise temperatures in degrees Kelvin, does not require cryogenic noise sources for routine operation. It eliminates radiometer calibration errors associated with RF attenuation measurements. Calibrated noise source is required only for laboratory adjustment and calibration.

  12. COBE Final Report: Dirbe Celestial Calibration

    NASA Technical Reports Server (NTRS)

    Burdick, Shawn V.; Murdock, Thomas L.

    1997-01-01

    We report the results of a comparative study of the COsmic Background Explorer/Diffuse InfraRed Background Experiment (COBE/DIRBE) photometric calibration over about 100 selected stellar and non-stellar calibration objects across a wide range of the DIRBE instrument dynamic range, wavelength coverage, and source temperature. A statistical comparison of the DIRBE-reported flux to the accepted values from the literature (as summarized in the CIO) provides an independent verification of the DIRBE point source calibration.

  13. Bayesian Calibration of Microsimulation Models.

    PubMed

    Rutter, Carolyn M; Miglioretti, Diana L; Savarino, James E

    2009-12-01

    Microsimulation models that describe disease processes synthesize information from multiple sources and can be used to estimate the effects of screening and treatment on cancer incidence and mortality at a population level. These models are characterized by simulation of individual event histories for an idealized population of interest. Microsimulation models are complex and invariably include parameters that are not well informed by existing data. Therefore, a key component of model development is the choice of parameter values. Microsimulation model parameter values are selected to reproduce expected or known results though the process of model calibration. Calibration may be done by perturbing model parameters one at a time or by using a search algorithm. As an alternative, we propose a Bayesian method to calibrate microsimulation models that uses Markov chain Monte Carlo. We show that this approach converges to the target distribution and use a simulation study to demonstrate its finite-sample performance. Although computationally intensive, this approach has several advantages over previously proposed methods, including the use of statistical criteria to select parameter values, simultaneous calibration of multiple parameters to multiple data sources, incorporation of information via prior distributions, description of parameter identifiability, and the ability to obtain interval estimates of model parameters. We develop a microsimulation model for colorectal cancer and use our proposed method to calibrate model parameters. The microsimulation model provides a good fit to the calibration data. We find evidence that some parameters are identified primarily through prior distributions. Our results underscore the need to incorporate multiple sources of variability (i.e., due to calibration data, unknown parameters, and estimated parameters and predicted values) when calibrating and applying microsimulation models.

  14. Traceable Pyrgeometer Calibrations

    SciTech Connect

    Dooraghi, Mike; Kutchenreiter, Mark; Reda, Ibrahim; Habte, Aron; Sengupta, Manajit; Andreas, Afshin; Newman, Martina

    2016-05-02

    This poster presents the development, implementation, and operation of the Broadband Outdoor Radiometer Calibrations (BORCAL) Longwave (LW) system at the Southern Great Plains Radiometric Calibration Facility for the calibration of pyrgeometers that provide traceability to the World Infrared Standard Group.

  15. Calibration of hydrometers

    NASA Astrophysics Data System (ADS)

    Lorefice, Salvatore; Malengo, Andrea

    2006-10-01

    After a brief description of the different methods employed in periodic calibration of hydrometers used in most cases to measure the density of liquids in the range between 500 kg m-3 and 2000 kg m-3, particular emphasis is given to the multipoint procedure based on hydrostatic weighing, known as well as Cuckow's method. The features of the calibration apparatus and the procedure used at the INRiM (formerly IMGC-CNR) density laboratory have been considered to assess all relevant contributions involved in the calibration of different kinds of hydrometers. The uncertainty is strongly dependent on the kind of hydrometer; in particular, the results highlight the importance of the density of the reference buoyant liquid, the temperature of calibration and the skill of operator in the reading of the scale in the whole assessment of the uncertainty. It is also interesting to realize that for high-resolution hydrometers (division of 0.1 kg m-3), the uncertainty contribution of the density of the reference liquid is the main source of the total uncertainty, but its importance falls under about 50% for hydrometers with a division of 0.5 kg m-3 and becomes somewhat negligible for hydrometers with a division of 1 kg m-3, for which the reading uncertainty is the predominant part of the total uncertainty. At present the best INRiM result is obtained with commercially available hydrometers having a scale division of 0.1 kg m-3, for which the relative uncertainty is about 12 × 10-6.

  16. Calibration of sound calibrators: an overview

    NASA Astrophysics Data System (ADS)

    Milhomem, T. A. B.; Soares, Z. M. D.

    2016-07-01

    This paper presents an overview of calibration of sound calibrators. Initially, traditional calibration methods are presented. Following, the international standard IEC 60942 is discussed emphasizing parameters, target measurement uncertainty and criteria for conformance to the requirements of the standard. Last, Regional Metrology Organizations comparisons are summarized.

  17. Calibration Monitor for Dark Energy Experiments

    SciTech Connect

    Kaiser, M. E.

    2009-11-23

    The goal of this program was to design, build, test, and characterize a flight qualified calibration source and monitor for a Dark Energy related experiment: ACCESS - 'Absolute Color Calibration Experiment for Standard Stars'. This calibration source, the On-board Calibration Monitor (OCM), is a key component of our ACCESS spectrophotometric calibration program. The OCM will be flown as part of the ACCESS sub-orbital rocket payload in addition to monitoring instrument sensitivity on the ground. The objective of the OCM is to minimize systematic errors associated with any potential changes in the ACCESS instrument sensitivity. Importantly, the OCM will be used to monitor instrument sensitivity immediately after astronomical observations while the instrument payload is parachuting to the ground. Through monitoring, we can detect, track, characterize, and thus correct for any changes in instrument senstivity over the proposed 5-year duration of the assembled and calibrated instrument.

  18. Sources of Variability in Chlorophyll Analysis by Fluorometry and High-Performance Liquid Chromatography in a SIMBIOS Inter-Calibration Exercise

    NASA Technical Reports Server (NTRS)

    VanHeukelem, Laurie; Thomas, Crystal S.; Gilbert, Patricia M.; Fargion, Giulietta S. (Editor); McClain, Charles R. (Editor)

    2002-01-01

    The purpose of this technical report is to provide current documentation of the Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) Project activities, NASA Research Announcement (NRA) research status, satellite data processing, data product validation, and field calibration. This documentation is necessary to ensure that critical information is related to the scientific community and NASA management. This critical information includes the technical difficulties and challenges of validating and combining ocean color data from an array of independent satellite systems to form consistent and accurate global bio-optical time series products. This technical report is not meant as a substitute for scientific literature. Instead, it will provide a ready and responsive vehicle for the multitude of technical reports issued by an operational project. This particular document focus on the variability in chlorophyll pigment measurements resulting from differences in methodologies and laboratories conducting the pigment analysis.

  19. COBE differential microwave radiometers - Calibration techniques

    NASA Technical Reports Server (NTRS)

    Bennett, C. L.; Smoot, G. F.; Janssen, M.; Gulkis, S.; Kogut, A.; Hinshaw, G.; Backus, C.; Hauser, M. G.; Mather, J. C.; Rokke, L.

    1992-01-01

    The COBE spacecraft was launched November 18, 1989 UT carrying three scientific instruments into earth orbit for studies of cosmology. One of these instruments, the Differential Microwave Radiometer (DMR), is designed to measure the large-angular-scale temperature anisotropy of the cosmic microwave background radiation at three frequencies (31.5, 53, and 90 GHz). This paper presents three methods used to calibrate the DMR. First, the signal difference between beam-filling hot and cold targets observed on the ground provides a primary calibration that is transferred to space by noise sources internal to the instrument. Second, the moon is used in flight as an external calibration source. Third, the signal arising from the Doppler effect due to the earth's motion around the barycenter of the solar system is used as an external calibration source. Preliminary analysis of the external source calibration techniques confirms the accuracy of the currently more precise ground-based calibration. Assuming the noise source behavior did not change from the ground-based calibration to flight, a 0.1-0.4 percent relative and 0.7-2.5 percent absolute calibration uncertainty is derived, depending on radiometer channel.

  20. Selection of stars to calibrate Gaia

    NASA Astrophysics Data System (ADS)

    Carrasco, J. M.; Voss, H.; Jordi, C.; Fabricius, C.; Pancino, E.; Altavilla, G.

    2015-05-01

    Gaia is an all-sky survey satellite, launched by ESA on 19th December 2013, to obtain parallaxes and proper motions to microarcsecond level precision, radial velocities and astrophysical parameters for about one billion objects down to a limiting magnitude of 20. The chosen strategy to perform the photometric calibration is to split the process into two steps, internal and external calibration. The internal calibration will combine all different transits of a given source to a common reference internal system producing a 'mean' Gaia observation. This internal calibration accounts for the differential instrumental effects (in sensitivity, aperture, PSF, etc.). They depend on the colour and type of the source. For this reason, a selection of calibration sources ensuring a good representation of all kind of observed sources is needed. The entire magnitude and colour range of the sources have to be covered by these calibration stars and for all calibration intervals. It is a challenge to obtain a suitable colour distribution for the standards, especially for bright sources and the daily large scale calibration intervals. Once the mean Gaia observations are produced, a final step, the external calibration, transforms them to absolute fluxes and wavelengths. In principle, few calibration sources are needed (about 200 spectrophotometric standard stars, SPSS, are currently being considered). They need to have accurate determinations of their absolute fluxes and their non-variability need to be ensured below 1% precision. For this purpose, a big international observational effort is being done (using telescopes as 2.2m@CAHA, TNG@LaPalma, NTT@LaSilla, LaRuca@SPM, and others). During this observational effort some cases of non-expected variability of the SPSS candidates have been discovered.

  1. 1987 calibration of the TFTR neutron spectrometers

    SciTech Connect

    Barnes, C.W.; Strachan, J.D.; Princeton Univ., NJ . Plasma Physics Lab.)

    1989-12-01

    The {sup 3}He neutron spectrometer used for measuring ion temperatures and the NE213 proton recoil spectrometer used for triton burnup measurements were absolutely calibrated with DT and DD neutron generators placed inside the TFTR vacuum vessel. The details of the detector response and calibration are presented. Comparisons are made to the neutron source strengths measured from other calibrated systems. 23 refs., 19 figs., 6 tabs.

  2. The Second VLBA Calibrator Survey: VCS2

    NASA Astrophysics Data System (ADS)

    Fomalont, E. B.; Petrov, L.; MacMillan, D. S.; Gordon, D.; Ma, C.

    2003-11-01

    This paper presents an extension of the Very Long Baseline Array Calibrator Survey, called VCS2, containing 276 sources. This survey fills in regions of the sky that were not completely covered by the previous VCS1 calibrator survey. The VCS2 survey includes calibrator sources near the Galactic plane, -30deg<δ<-45deg, and VLA calibrators. The positions have been derived from astrometric analysis of the group delays measured at 2.3 and 8.4 GHz using the Goddard Space Flight Center CALC/SOLVE package. From the VLBA snapshot observations, images of the calibrators are available, and each source is given a quality code for anticipated use. The VCS2 catalog is available from the NRAO Web site.

  3. Langley method of calibrating UV filter radiometers

    NASA Astrophysics Data System (ADS)

    Slusser, James; Gibson, James; Bigelow, David; Kolinski, Donald; Disterhoft, Patrick; Lantz, Kathleen; Beaubien, Arthur

    2000-02-01

    The Langley method of calibrating UV multifilter shadow band radiometers (UV-MFRSR) is explored in this paper. This method has several advantages over the traditional standard lamp calibrations: the Sun is a free, universally available, and very constant source, and nearly continual automated field calibrations can be made. Although 20 or so Langley events are required for an accurate calibration, the radiometer remains in the field during calibration. Difficulties arise as a result of changing ozone optical depth during the Langley event and the breakdown of the Beer-Lambert law over the finite filter band pass since optical depth changes rapidly with wavelength. The Langley calibration of the radiometers depends critically upon the spectral characterization of each channel and on the wavelength and absolute calibration of the extraterrestrial spectrum used. Results of Langley calibrations for two UV-MFRSRs at Mauna Loa, Hawaii were compared to calibrations using two National Institute of Standards and Technology (NIST) traceable lamps. The objectives of this study were to compare Langley calibration factors with those from standard lamps and to compare field-of-view effects. The two radiometers were run simultaneously: one on a Sun tracker and the other in the conventional shadow-band configuration. Both radiometers were calibrated with two secondary 1000 W lamp, and later, the spectral response functions of the channels were measured. The ratio of Langley to lamp calibration factors for the seven channels from 300 nm to 368 nm using the shadow-band configuration ranged from 0.988 to 1.070. The estimated uncertainty in accuracy of the Langley calibrations ranged from ±3.8% at 300 nm to ±2.1% at 368 nm. For all channels calibrated with Central Ultraviolet Calibration Facility (CUCF) lamps the estimated uncertainty was ±2.5% for all channels.

  4. A digital calibration method for synthetic aperture radar systems

    NASA Technical Reports Server (NTRS)

    Larson, Richard W.; Jackson, P. L.; Kasischke, Eric S.

    1988-01-01

    A basic method to calibrate imagery from synthetic aperture radar (SAR) systems is presented. SAR images are calibrated by monitoring all the terms of the radar equation. This procedure includes the use of both external (calibrated reference reflectors) and internal (system-generated calibration signals) sources to monitor the total SAR system transfer function. To illustrate the implementation of the procedure, two calibrated SAR images (X-band, 3.2-cm wavelength) are presented, along with the radar cross-section measurements of specific scenes within each image. The sources of error within the SAR image calibration procedure are identified.

  5. Calibration of X-Ray Observatories

    NASA Technical Reports Server (NTRS)

    Weisskopf, Martin C.; L'Dell, Stephen L.

    2011-01-01

    Accurate calibration of x-ray observatories has proved an elusive goal. Inaccuracies and inconsistencies amongst on-ground measurements, differences between on-ground and in-space performance, in-space performance changes, and the absence of cosmic calibration standards whose physics we truly understand have precluded absolute calibration better than several percent and relative spectral calibration better than a few percent. The philosophy "the model is the calibration" relies upon a complete high-fidelity model of performance and an accurate verification and calibration of this model. As high-resolution x-ray spectroscopy begins to play a more important role in astrophysics, additional issues in accurately calibrating at high spectral resolution become more evident. Here we review the challenges of accurately calibrating the absolute and relative response of x-ray observatories. On-ground x-ray testing by itself is unlikely to achieve a high-accuracy calibration of in-space performance, especially when the performance changes with time. Nonetheless, it remains an essential tool in verifying functionality and in characterizing and verifying the performance model. In the absence of verified cosmic calibration sources, we also discuss the notion of an artificial, in-space x-ray calibration standard. 6th

  6. FY2008 Calibration Systems Final Report

    SciTech Connect

    Cannon, Bret D.; Myers, Tanya L.; Broocks, Bryan T.

    2009-01-01

    The Calibrations project has been exploring alternative technologies for calibration of passive sensors in the infrared (IR) spectral region. In particular, we have investigated using quantum cascade lasers (QCLs) because these devices offer several advantages over conventional blackbodies such as reductions in size and weight while providing a spectral source in the IR with high output power. These devices can provide a rapid, multi-level radiance scheme to fit any nonlinear behavior as well as a spectral calibration that includes the fore-optics, which is currently not available for on-board calibration systems.

  7. Calibration services for medical applications of radiation

    SciTech Connect

    DeWerd, L.A.

    1993-12-31

    Calibration services for the medical community applications of radiation involve measuring radiation precisely and having traceability to the National Institute of Standards and Technology (NIST). Radiation therapy applications involve the use of ionization chambers and electrometers for external beams and well-type ionization chamber systems as well as radioactive sources for brachytherapy. Diagnostic x-ray applications involve ionization chamber systems and devices to measure other parameters of the x-ray machine, such as non-invasive kVp meters. Calibration laboratories have been established to provide radiation calibration services while maintaining traceability to NIST. New radiation applications of the medical community spur investigation to provide the future calibration needs.

  8. Technique for Radiometer and Antenna Array Calibration with Two Antenna Noise Diodes

    NASA Technical Reports Server (NTRS)

    Srinivasan, Karthik; Limaye, Ashutosh; Laymon, Charles; Meyer, Paul

    2011-01-01

    This paper presents a new technique to calibrate a microwave radiometer and phased array antenna system. This calibration technique uses a radiated noise source in addition to an injected noise sources for calibration. The plane of reference for this calibration technique is the face of the antenna and therefore can effectively calibration the gain fluctuations in the active phased array antennas. This paper gives the mathematical formulation for the technique and discusses the improvements brought by the method over the existing calibration techniques.

  9. MODIS airborne simulator visible and near-infrared calibration, 1992 ASTEX field experiment. Calibration version: ASTEX King 1.0

    NASA Technical Reports Server (NTRS)

    Arnold, G. Thomas; Fitzgerald, Michael; Grant, Patrick S.; King, Michael D.

    1994-01-01

    Calibration of the visible and near-infrared (near-IR) channels of the MODIS Airborne Simulator (MAS) is derived from observations of a calibrated light source. For the 1992 Atlantic Stratocumulus Transition Experiment (ASTEX) field deployment, the calibrated light source was the NASA Goddard 48-inch integrating hemisphere. Tests during the ASTEX deployment were conducted to calibrate the hemisphere and then the MAS. This report summarizes the ASTEX hemisphere calibration, and then describes how the MAS was calibrated from the hemisphere data. All MAS calibration measurements are presented and determination of the MAS calibration coefficients (raw counts to radiance conversion) is discussed. In addition, comparisons to an independent MAS calibration by Ames personnel using their 30-inch integrating sphere is discussed.

  10. New numerical simulation method to calibrate the regular hexagonal NaI(Tl) detector with radioactive point sources situated non-axial.

    PubMed

    Hamzawy, Ayman; Grozdanov, Dimitar N; Badawi, Mohamed S; Aliyev, Fuad A; Thabet, Abouzeid A; Abbas, Mahmoud I; Ruskov, Ivan N; El-Khatib, Ahmed M; Kopatch, Yuri N; Gouda, Mona M

    2016-11-01

    Scintillation crystals are usually used for detection of energetic photons at room temperature in high energy and nuclear physics research, non-destructive analysis of materials testing, safeguards, nuclear treaty verification, geological exploration, and medical imaging. Therefore, new designs and construction of radioactive beam facilities are coming on-line with these science brunches. A good number of researchers are investigating the efficiency of the γ-ray detectors to improve the models and techniques used in order to deal with the most pressing problems in physics research today. In the present work, a new integrative and uncomplicated numerical simulation method (NSM) is used to compute the full-energy (photo) peak efficiency of a regular hexagonal prism NaI(Tl) gamma-ray detector using radioactive point sources situated non-axial within its front surface boundaries. This simulation method is based on the efficiency transfer method. Most of the mathematical formulas in this work are derived analytically and solved numerically. The main core of the NSM is the calculation of the effective solid angle for radioactive point sources, which are situated non-axially at different distances from the front surface of the detector. The attenuation of the γ-rays through the detector's material and any other materials in-between the source and the detector is taken into account. A remarkable agreement between the experimental and calculated by present formalism results has been observed.

  11. New numerical simulation method to calibrate the regular hexagonal NaI(Tl) detector with radioactive point sources situated non-axial

    NASA Astrophysics Data System (ADS)

    Hamzawy, Ayman; Grozdanov, Dimitar N.; Badawi, Mohamed S.; Aliyev, Fuad A.; Thabet, Abouzeid A.; Abbas, Mahmoud I.; Ruskov, Ivan N.; El-Khatib, Ahmed M.; Kopatch, Yuri N.; Gouda, Mona M.

    2016-11-01

    Scintillation crystals are usually used for detection of energetic photons at room temperature in high energy and nuclear physics research, non-destructive analysis of materials testing, safeguards, nuclear treaty verification, geological exploration, and medical imaging. Therefore, new designs and construction of radioactive beam facilities are coming on-line with these science brunches. A good number of researchers are investigating the efficiency of the γ-ray detectors to improve the models and techniques used in order to deal with the most pressing problems in physics research today. In the present work, a new integrative and uncomplicated numerical simulation method (NSM) is used to compute the full-energy (photo) peak efficiency of a regular hexagonal prism NaI(Tl) gamma-ray detector using radioactive point sources situated non-axial within its front surface boundaries. This simulation method is based on the efficiency transfer method. Most of the mathematical formulas in this work are derived analytically and solved numerically. The main core of the NSM is the calculation of the effective solid angle for radioactive point sources, which are situated non-axially at different distances from the front surface of the detector. The attenuation of the γ-rays through the detector's material and any other materials in-between the source and the detector is taken into account. A remarkable agreement between the experimental and calculated by present formalism results has been observed.

  12. Astrophysical calibration of gravitational-wave detectors

    NASA Astrophysics Data System (ADS)

    Pitkin, M.; Messenger, C.; Wright, L.

    2016-03-01

    We investigate a method to assess the validity of gravitational-wave detector calibration through the use of gamma-ray bursts as standard sirens. Such signals, as measured via gravitational-wave observations, provide an estimated luminosity distance that is subject to uncertainties in the calibration of the data. If a host galaxy is identified for a given source then its redshift can be combined with current knowledge of the cosmological parameters yielding the true luminosity distance. This will then allow a direct comparison with the estimated value and can validate the accuracy of the original calibration. We use simulations of individual detectable gravitational-wave signals from binary neutron star (BNS) or neutron star-black hole systems, which we assume to be found in coincidence with short gamma-ray bursts, to estimate any discrepancy in the overall scaling of the calibration for detectors in the Advanced LIGO and Advanced Virgo network. We find that the amplitude scaling of the calibration for the LIGO instruments could on average be confirmed to within ˜10 % for a BNS source within 100 Mpc. This result is largely independent of the current detector calibration method and gives an uncertainty that is competitive with that expected in the current calibration procedure. Confirmation of the calibration accuracy to within ˜20 % can be found with BNS sources out to ˜500 Mpc .

  13. Self-calibrating multiplexer circuit

    DOEpatents

    Wahl, Chris P.

    1997-01-01

    A time domain multiplexer system with automatic determination of acceptable multiplexer output limits, error determination, or correction is comprised of a time domain multiplexer, a computer, a constant current source capable of at least three distinct current levels, and two series resistances employed for calibration and testing. A two point linear calibration curve defining acceptable multiplexer voltage limits may be defined by the computer by determining the voltage output of the multiplexer to very accurately known input signals developed from predetermined current levels across the series resistances. Drift in the multiplexer may be detected by the computer when the output voltage limits, expected during normal operation, are exceeded, or the relationship defined by the calibration curve is invalidated.

  14. Absolute sensitivity calibration of extreme ultraviolet photoresists

    SciTech Connect

    Jones, Juanita; Naulleau, Patrick P.; Gullikson, Eric M.; Aquila, Andrew; George, Simi; Niakoula, Dimitra

    2008-05-16

    One of the major challenges facing the commercialization of extreme ultraviolet (EUV) lithography remains simultaneously achieving resist sensitivity, line-edge roughness, and resolution requirement. Sensitivity is of particular concern owing to its direct impact on source power requirements. Most current EUV exposure tools have been calibrated against a resist standard with the actual calibration of the standard resist dating back to EUV exposures at Sandia National Laboratories in the mid 1990s. Here they report on an independent sensitivity calibration of two baseline resists from the SEMATECH Berkeley MET tool performed at the Advanced Light Source Calibrations and Standards beamline. The results show the baseline resists to be approximately 1.9 times faster than previously thought based on calibration against the long standing resist standard.

  15. A derivative standard for polarimeter calibration

    SciTech Connect

    Mulhollan, G.; Clendenin, J.; Saez, P.

    1996-10-01

    A long-standing problem in polarized electron physics is the lack of a traceable standard for calibrating electron spin polarimeters. While several polarimeters are absolutely calibrated to better than 2%, the typical instrument has an inherent accuracy no better than 10%. This variability among polarimeters makes it difficult to compare advances in polarized electron sources between laboratories. The authors have undertaken an effort to establish 100 nm thick molecular beam epitaxy grown GaAs(110) as a material which may be used as a derivative standard for calibrating systems possessing a solid state polarized electron source. The near-bandgap spin polarization of photoelectrons emitted from this material has been characterized for a variety of conditions and several laboratories which possess well calibrated polarimeters have measured the photoelectron polarization of cathodes cut from a common wafer. Despite instrumentation differences, the spread in the measurements is sufficiently small that this material may be used as a derivative calibration standard.

  16. Absolute sensitivity calibration of extreme ultraviolet photoresists.

    PubMed

    Naulleau, Patrick P; Gullikson, Eric M; Aquila, Andrew; George, Simi; Niakoula, Dimitra

    2008-07-21

    One of the major challenges facing the commercialization of extreme ultraviolet (EUV) lithography remains simultaneously achieving resist sensitivity, line-edge roughness, and resolution requirement. Sensitivity is of particular concern owing to its direct impact on source power requirements. Most current EUV exposure tools have been calibrated against a resist standard with the actual calibration of the standard resist dating back to EUV exposures at Sandia National Laboratories in the mid 1990s. Here we report on an independent sensitivity calibration of two baseline resists from the SEMATECH Berkeley MET tool performed at the Advanced Light Source Calibrations and Standards beamline. The results show the baseline resists to be approximately 1.9 times faster than previously thought based on calibration against the long standing resist standard.

  17. Improving self-calibration.

    PubMed

    Enßlin, Torsten A; Junklewitz, Henrik; Winderling, Lars; Greiner, Maksim; Selig, Marco

    2014-10-01

    Response calibration is the process of inferring how much the measured data depend on the signal one is interested in. It is essential for any quantitative signal estimation on the basis of the data. Here, we investigate self-calibration methods for linear signal measurements and linear dependence of the response on the calibration parameters. The common practice is to augment an external calibration solution using a known reference signal with an internal calibration on the unknown measurement signal itself. Contemporary self-calibration schemes try to find a self-consistent solution for signal and calibration by exploiting redundancies in the measurements. This can be understood in terms of maximizing the joint probability of signal and calibration. However, the full uncertainty structure of this joint probability around its maximum is thereby not taken into account by these schemes. Therefore, better schemes, in sense of minimal square error, can be designed by accounting for asymmetries in the uncertainty of signal and calibration. We argue that at least a systematic correction of the common self-calibration scheme should be applied in many measurement situations in order to properly treat uncertainties of the signal on which one calibrates. Otherwise, the calibration solutions suffer from a systematic bias, which consequently distorts the signal reconstruction. Furthermore, we argue that nonparametric, signal-to-noise filtered calibration should provide more accurate reconstructions than the common bin averages and provide a new, improved self-calibration scheme. We illustrate our findings with a simplistic numerical example.

  18. Calibration issues for neutron diagnostics

    SciTech Connect

    Sadler, G.J.; Adams, J.M.; Barnes, C.W.

    1997-12-01

    The performance of diagnostic systems are limited by their weakest constituents, including their calibration issues. Neutron diagnostics are notorious for problems encountered while determining their absolute calibrations, due mainly to the nature of the neutron transport problem. In order to facilitate the determination of an accurate and precise calibration, the diagnostic design should be such as to minimize the scattered neutron flux. ITER will use a comprehensive set of neutron diagnostics--comprising radial and vertical neutron cameras, neutron spectrometers, a neutron activation system and internal and external fission chambers--to provide accurate measurements of fusion power and power densities as a function of time. The calibration of such an important diagnostic system merits careful consideration. Some thoughts have already been given to this subject during the conceptual design phase in relation to the time-integrated neutron activation and time-dependent neutron yield monitors. However, no overall calibration strategy has been worked out so far. This paper represents a first attempt to address this vital issue. Experience gained from present large tokamaks (JET, TFTR and JT60U) and proposals for ITER are reviewed. The need to use a 14-MeV neutron generator as opposed to radioactive sources for in-situ calibration of D-T diagnostics will be stressed. It is clear that the overall absolute determination of fusion power will have to rely on a combination of nuclear measuring techniques, for which the provision of accurate and independent calibrations will constitute an ongoing process as ITER moves from one phase of operation to the next.

  19. Calibration of pneumotachographs using a calibrated syringe.

    PubMed

    Tang, Yongquan; Turner, Martin J; Yem, Johnny S; Baker, A Barry

    2003-08-01

    Pneumotachograph require frequent calibration. Constant-flow methods allow polynomial calibration curves to be derived but are time consuming. The iterative syringe stroke technique is moderately efficient but results in discontinuous conductance arrays. This study investigated the derivation of first-, second-, and third-order polynomial calibration curves from 6 to 50 strokes of a calibration syringe. We used multiple linear regression to derive first-, second-, and third-order polynomial coefficients from two sets of 6-50 syringe strokes. In part A, peak flows did not exceed the specified linear range of the pneumotachograph, whereas flows in part B peaked at 160% of the maximum linear range. Conductance arrays were derived from the same data sets by using a published algorithm. Volume errors of the calibration strokes and of separate sets of 70 validation strokes (part A) and 140 validation strokes (part B) were calculated by using the polynomials and conductance arrays. Second- and third-order polynomials derived from 10 calibration strokes achieved volume variability equal to or better than conductance arrays derived from 50 strokes. We found that evaluation of conductance arrays using the calibration syringe strokes yields falsely low volume variances. We conclude that accurate polynomial curves can be derived from as few as 10 syringe strokes, and the new polynomial calibration method is substantially more time efficient than previously published conductance methods.

  20. Calibration of the ROSAT HRI Spectral Response

    NASA Technical Reports Server (NTRS)

    Prestwich, Andrea H.; Silverman, John; McDowell, Jonathan; Callanan, Paul; Snowden, Steve

    2000-01-01

    The ROSAT High Resolution Imager has a limited (2-band) spectral response. This spectral capability can give X-ray hardness ratios on spatial scales of 5 arcseconds. The spectral response of the center of the detector was calibrated before the launch of ROSAT, but the gain decreases with time and also is a function of position on the detector. To complicate matters further, the satellite is 'wobbled', possibly moving a source across several spatial gain states. These difficulties have prevented the spectral response of the ROSAT High Resolution Imager (HRI) from being used for scientific measurements. We have used Bright Earth data and in-flight calibration sources to map the spatial and temporal gain changes, and written software which will allow ROSAT users to generate a calibrated XSPEC (an x ray spectral fitting package) response matrix and hence determine a calibrated hardness ratio. In this report, we describe the calibration procedure and show how to obtain a response matrix. In Section 2 we give an overview of the calibration procedure, in Section 3 we give a summary of HRI spatial and temporal gain variations. Section 4 describes the routines used to determine the gain distribution of a source. In Sections 5 and 6, we describe in detail how, the Bright Earth database and calibration sources are used to derive a corrected response matrix for a given observation. Finally, Section 7 describes how to use the software.

  1. Calibration of the ROSAT HRI Spectral Response

    NASA Technical Reports Server (NTRS)

    Prestwich, Andrea

    1998-01-01

    The ROSAT High Resolution Imager has a limited (2-band) spectral response. This spectral capability can give X-ray hardness ratios on spatial scales of 5 arcseconds. The spectral response of the center of the detector was calibrated before the launch of ROSAT, but the gain decreases-with time and also is a function of position on the detector. To complicate matters further, the satellite is "wobbled", possibly moving a source across several spatial gain states. These difficulties have prevented the spectral response of the ROSAT HRI from being used for scientific measurements. We have used Bright Earth data and in-flight calibration sources to map the spatial and temporal gain changes, and written software which will allow ROSAT users to generate a calibrated XSPEC response matrix and hence determine a calibrated hardness ratio. In this report, we describe the calibration procedure and show how to obtain a response matrix. In Section 2 we give an overview of the calibration procedure, in Section 3 we give a summary of HRI spatial and temporal gain variations. Section 4 describes the routines used to determine the gain distribution of a source. In Sections 5 and 6, we describe in detail how the Bright Earth database and calibration sources are used to derive a corrected response matrix for a given observation. Finally, Section 7 describes how to use the software.

  2. Technique for Radiometer and Antenna Array Calibration with a Radiated Noise Diode

    NASA Technical Reports Server (NTRS)

    Srinivasan, Karthik; Limaye, Ashutosh; Laymon, Charles; Meyer, Paul

    2009-01-01

    This paper presents a new technique to calibrate a microwave radiometer and antenna array system. This calibration technique uses a radiated noise source in addition to two calibration sources internal to the radiometer. The method accurately calibrates antenna arrays with embedded active devices (such as amplifiers) which are used extensively in active phased array antennas.

  3. Real-time calibration-free C-scan images of the eye fundus using Master Slave swept source optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Bradu, Adrian; Kapinchev, Konstantin; Barnes, Fred; Garway-Heath, David F.; Rajendram, Ranjan; Keane, Pearce; Podoleanu, Adrian G.

    2015-03-01

    Recently, we introduced a novel Optical Coherence Tomography (OCT) method, termed as Master Slave OCT (MS-OCT), specialized for delivering en-face images. This method uses principles of spectral domain interfereometry in two stages. MS-OCT operates like a time domain OCT, selecting only signals from a chosen depth only while scanning the laser beam across the eye. Time domain OCT allows real time production of an en-face image, although relatively slowly. As a major advance, the Master Slave method allows collection of signals from any number of depths, as required by the user. The tremendous advantage in terms of parallel provision of data from numerous depths could not be fully employed by using multi core processors only. The data processing required to generate images at multiple depths simultaneously is not achievable with commodity multicore processors only. We compare here the major improvement in processing and display, brought about by using graphic cards. We demonstrate images obtained with a swept source at 100 kHz (which determines an acquisition time [Ta] for a frame of 200×200 pixels2 of Ta =1.6 s). By the end of the acquired frame being scanned, using our computing capacity, 4 simultaneous en-face images could be created in T = 0.8 s. We demonstrate that by using graphic cards, 32 en-face images can be displayed in Td 0.3 s. Other faster swept source engines can be used with no difference in terms of Td. With 32 images (or more), volumes can be created for 3D display, using en-face images, as opposed to the current technology where volumes are created using cross section OCT images.

  4. Analytical multicollimator camera calibration

    USGS Publications Warehouse

    Tayman, W.P.

    1978-01-01

    Calibration with the U.S. Geological survey multicollimator determines the calibrated focal length, the point of symmetry, the radial distortion referred to the point of symmetry, and the asymmetric characteristiecs of the camera lens. For this project, two cameras were calibrated, a Zeiss RMK A 15/23 and a Wild RC 8. Four test exposures were made with each camera. Results are tabulated for each exposure and averaged for each set. Copies of the standard USGS calibration reports are included. ?? 1978.

  5. Definition of energy-calibrated spectra for national reachback

    SciTech Connect

    Kunz, Christopher L.; Hertz, Kristin L.

    2014-01-01

    Accurate energy calibration is critical for the timeliness and accuracy of analysis results of spectra submitted to National Reachback, particularly for the detection of threat items. Many spectra submitted for analysis include either a calibration spectrum using 137Cs or no calibration spectrum at all. The single line provided by 137Cs is insufficient to adequately calibrate nonlinear spectra. A calibration source that provides several lines that are well-spaced, from the low energy cutoff to the full energy range of the detector, is needed for a satisfactory energy calibration. This paper defines the requirements of an energy calibration for the purposes of National Reachback, outlines a method to validate whether a given spectrum meets that definition, discusses general source considerations, and provides a specific operating procedure for calibrating the GR-135.

  6. Quality assurance programs at the PNL calibrations laboratory

    SciTech Connect

    Piper, R.K.; McDonald, J.C.; Fox, R.A.; Eichner, F.N.

    1993-03-01

    The calibrations laboratory at Pacific Northwest Laboratory (PNL) serves as a radiological standardization facility for personnel and environmental dosimetry and radiological survey instruments. As part of this function, the calibrations laboratory must maintain radiological reference fields with calibrations traceable to the National Institute of Standards and Technology (NIST). This task is accomplished by a combination of (1) sources or reference instruments calibrated at or by NIST, (2) measurement quality assurance (MQA) interactions with NIST, and (3) rigorous internal annual and quarterly calibration verifications. This paper describes a representative sample of the facilities, sources, and actions used to maintain accurate and traceable fields.

  7. Research on calibration method of relative infrared radiometer

    NASA Astrophysics Data System (ADS)

    Yang, Sen; Li, Chengwei

    2016-02-01

    The Relative Infrared Radiometer (RIR) is commonly used to measure the irradiance of the Infrared Target Simulator (ITS), and the calibration of the RIR is central for the measurement accuracy. RIR calibration is conventionally performed using the Radiance Based (RB) calibration method or Irradiance Based (IB) calibration method, and the relationship between the radiation of standard source and the response of RIR is determined by curve fitting. One limitation existing in the calibration of RIR is the undesirable calibration voltage fluctuation in single measurement or in the reproducibility measurement, which reduces the calibration reproducibility and irradiance measurement accuracy. To address this limitation, the Equivalent Blackbody Temperature Based (EBTB) calibration method is proposed for the calibration of RIR. The purpose of this study is to compare the proposed EBTB calibration method with conventional RB and IB calibration methods. The comparison and experiment results have shown that the EBTB calibration method is not only able to provide comparable correlation between radiation and response to other calibration methods (IB and RB) in the irradiance measurement but also reduces the influence of calibration voltage fluctuation on the irradiance measurement result, which improves the calibration reproducibility and irradiance measurement accuracy.

  8. The LED calibration system of the SPHERE-2 detector

    NASA Astrophysics Data System (ADS)

    Antonov, R. A.; Bonvech, E. A.; Chernov, D. V.; Podgrudkov, D. A.; Roganova, T. M.

    2016-04-01

    An absolute calibration method for the PMT mosaic used in the SPHERE-2 experiment is presented. The method is based on the relative calibration of all PMTs in the mosaic to a single stable PMT, incorporated in it, during each measurement event and subsequent absolute calibration of that single PMT using a known stable light source. The results of the SPHERE-2 detector PMTs calibration are presented and are discussed.

  9. SUMS calibration test report

    NASA Technical Reports Server (NTRS)

    Robertson, G.

    1982-01-01

    Calibration was performed on the shuttle upper atmosphere mass spectrometer (SUMS). The results of the calibration and the as run test procedures are presented. The output data is described, and engineering data conversion factors, tables and curves, and calibration on instrument gauges are included. Static calibration results which include: instrument sensitive versus external pressure for N2 and O2, data from each scan of calibration, data plots from N2 and O2, and sensitivity of SUMS at inlet for N2 and O2, and ratios of 14/28 for nitrogen and 16/32 for oxygen are given.

  10. Landsat Data Continuity Mission Calibration and Validation

    NASA Technical Reports Server (NTRS)

    Markham, Brian L.; Dabney, Philip W.; Storey, James C.; Morfitt, Ron; Knight, Ed; Kvaran, Geir; Lee, Kenton

    2008-01-01

    The primary payload for the Landsat Data Continuity Mission (LDCM) is the Operational Land Imager (OLI), being built by Ball Aerospace and Technologies, under contract to NASA. The OLI has spectral bands similar to the Landsat-7 ETM+, minus the thermal band and with two new bands, a 443 nm band and 1375 nm cirrus detection band. On-board calibration systems include two solar diffusers (routine and pristine), a shutter and three sets of internal lamps (routine, backup and pristine). Being a pushbroom opposed to a whiskbroom design of ETM+, the system poses new challenges for characterization and calibration, chief among them being the large focal plane with 75000+ detectors. A comprehensive characterization and calibration plan is in place for the instrument and the data throughout the mission including Ball, NASA and the United States Geological Survey, which will take over operations of LDCM after on-orbit commissioning. Driving radiometric calibration requirements for OLI data include radiance calibration to 5% uncertainty (1 q); reflectance calibration to 3% uncertainty (1 q) and relative (detector-to-detector) calibration to 0.5% (J (r). Driving geometric calibration requirements for OLI include bandto- band registration of 4.5 meters (90% confidence), absolute geodetic accuracy of 65 meters (90% CE) and relative geodetic accuracy of 25 meters (90% CE). Key spectral, spatial and radiometric characterization of the OLI will occur in thermal vacuum at Ball Aerospace. During commissioning the OLI will be characterized and calibrated using celestial (sun, moon, stars) sources and terrestrial sources. The USGS EROS ground processing system will incorporate an image assessment system similar to Landsat-7 for characterization and calibration. This system will have the added benefit that characterization data will be extracted as part of the normal image data processing, so that the characterization data available will be significantly larger than for Landsat-7 ETM+.

  11. Flow through electrode with automated calibration

    DOEpatents

    Szecsody, James E [Richland, WA; Williams, Mark D [Richland, WA; Vermeul, Vince R [Richland, WA

    2002-08-20

    The present invention is an improved automated flow through electrode liquid monitoring system. The automated system has a sample inlet to a sample pump, a sample outlet from the sample pump to at least one flow through electrode with a waste port. At least one computer controls the sample pump and records data from the at least one flow through electrode for a liquid sample. The improvement relies upon (a) at least one source of a calibration sample connected to (b) an injection valve connected to said sample outlet and connected to said source, said injection valve further connected to said at least one flow through electrode, wherein said injection valve is controlled by said computer to select between said liquid sample or said calibration sample. Advantages include improved accuracy because of more frequent calibrations, no additional labor for calibration, no need to remove the flow through electrode(s), and minimal interruption of sampling.

  12. Absolute flux density calibrations: Receiver saturation effects

    NASA Technical Reports Server (NTRS)

    Freiley, A. J.; Ohlson, J. E.; Seidel, B. L.

    1978-01-01

    The effect of receiver saturation was examined for a total power radiometer which uses an ambient load for calibration. Extension to other calibration schemes is indicated. The analysis shows that a monotonic receiver saturation characteristic could cause either positive or negative measurement errors, with polarity depending upon operating conditions. A realistic model of the receiver was made by using a linear-cubic voltage transfer characteristic. The evaluation of measurement error for this model provided a means for correcting radio source measurements.

  13. Autotune Calibrates Models to Building Use Data

    SciTech Connect

    2016-08-26

    Models of existing buildings are currently unreliable unless calibrated manually by a skilled professional. Autotune, as the name implies, automates this process by calibrating the model of an existing building to measured data, and is now available as open source software. This enables private businesses to incorporate Autotune into their products so that their customers can more effectively estimate cost savings of reduced energy consumption measures in existing buildings.

  14. Autotune Calibrates Models to Building Use Data

    ScienceCinema

    None

    2016-09-02

    Models of existing buildings are currently unreliable unless calibrated manually by a skilled professional. Autotune, as the name implies, automates this process by calibrating the model of an existing building to measured data, and is now available as open source software. This enables private businesses to incorporate Autotune into their products so that their customers can more effectively estimate cost savings of reduced energy consumption measures in existing buildings.

  15. SAR calibration technology review

    NASA Technical Reports Server (NTRS)

    Walker, J. L.; Larson, R. W.

    1981-01-01

    Synthetic Aperture Radar (SAR) calibration technology including a general description of the primary calibration techniques and some of the factors which affect the performance of calibrated SAR systems are reviewed. The use of reference reflectors for measurement of the total system transfer function along with an on-board calibration signal generator for monitoring the temporal variations of the receiver to processor output is a practical approach for SAR calibration. However, preliminary error analysis and previous experimental measurements indicate that reflectivity measurement accuracies of better than 3 dB will be difficult to achieve. This is not adequate for many applications and, therefore, improved end-to-end SAR calibration techniques are required.

  16. PACS photometer calibration block analysis

    NASA Astrophysics Data System (ADS)

    Moór, A.; Müller, T. G.; Kiss, C.; Balog, Z.; Billot, N.; Marton, G.

    2014-07-01

    The absolute stability of the PACS bolometer response over the entire mission lifetime without applying any corrections is about 0.5 % (standard deviation) or about 8 % peak-to-peak. This fantastic stability allows us to calibrate all scientific measurements by a fixed and time-independent response file, without using any information from the PACS internal calibration sources. However, the analysis of calibration block observations revealed clear correlations of the internal source signals with the evaporator temperature and a signal drift during the first half hour after the cooler recycling. These effects are small, but can be seen in repeated measurements of standard stars. From our analysis we established corrections for both effects which push the stability of the PACS bolometer response to about 0.2 % (stdev) or 2 % in the blue, 3 % in the green and 5 % in the red channel (peak-to-peak). After both corrections we still see a correlation of the signals with PACS FPU temperatures, possibly caused by parasitic heat influences via the Kevlar wires which connect the bolometers with the PACS Focal Plane Unit. No aging effect or degradation of the photometric system during the mission lifetime has been found.

  17. Solar-Reflectance-Based Calibration of Spectral Radiometers

    NASA Technical Reports Server (NTRS)

    Cattrall, Christopher; Carder, Kendall L.; Thome, Kurtis J.; Gordon, Howard R.

    2001-01-01

    A method by which to calibrate a spectral radiometer using the sun as the illumination source is discussed. Solar-based calibrations eliminate several uncertainties associated with applying a lamp-based calibration to field measurements. The procedure requires only a calibrated reflectance panel, relatively low aerosol optical depth, and measurements of atmospheric transmittance. Further, a solar-reflectance-based calibration (SRBC), by eliminating the need for extraterrestrial irradiance spectra, reduces calibration uncertainty to approximately 2.2% across the solar-reflective spectrum, significantly reducing uncertainty in measurements used to deduce the optical properties of a system illuminated by the sun (e.g., sky radiance). The procedure is very suitable for on-site calibration of long-term field instruments, thereby reducing the logistics and costs associated with transporting a radiometer to a calibration facility.

  18. Spinning angle optical calibration apparatus

    DOEpatents

    Beer, Stephen K.; Pratt, II, Harold R.

    1991-01-01

    An optical calibration apparatus is provided for calibrating and reproducing spinning angles in cross-polarization, nuclear magnetic resonance spectroscopy. An illuminated magnifying apparatus enables optical setting an accurate reproducing of spinning "magic angles" in cross-polarization, nuclear magnetic resonance spectroscopy experiments. A reference mark scribed on an edge of a spinning angle test sample holder is illuminated by a light source and viewed through a magnifying scope. When the "magic angle" of a sample material used as a standard is attained by varying the angular position of the sample holder, the coordinate position of the reference mark relative to a graduation or graduations on a reticle in the magnifying scope is noted. Thereafter, the spinning "magic angle" of a test material having similar nuclear properties to the standard is attained by returning the sample holder back to the originally noted coordinate position.

  19. PROSPECT: Optical Calibration System

    NASA Astrophysics Data System (ADS)

    Trinh, Ken; Prospect Collaboration

    2016-09-01

    The Precision Reactor Oscillation and SPECTrum Experiment (PROSPECT), is a short baseline, reactor neutrino experiment which focuses on measurements of the flux and energy spectrum of antineutrinos emitted from the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. Using these measurements, PROSPECT will probe for eV-scale sterile neutrinos while making a high precision measurement of the U-235 antineutrino spectrum. PROSPECT contains two phases; the first phase consists of a mobile detector near the reactor core while the second phase adds a larger fixed detector further from the core. The PROSPECT Phase 1 detector consists of a 2ton optically segmented liquid scintillator with each segment read-out by two photomultiplier tubes (PMTs). The PMTs are calibrated with a photon source generated by a nanosecond pulsed laser. In this project, we developed a plan to determine the effectiveness of a 450nm fiber-pigtailed diode laser as it coupled with several modules including an optical fiber splitter, an optical diffuser, and an attenuator. The project tested for the system ability to deliver light uniformly to each of the cells in the detector. We will present the design and result of this project as well as discuss how it will be implemented in PROSPECT.

  20. Evaluation of computational radiometric and spectral sensor calibration techniques

    NASA Astrophysics Data System (ADS)

    Manakov, Alkhazur

    2016-04-01

    Radiometric and spectral calibration are essential for enabling the use of digital sensors for measurement purposes. Traditional optical calibration techniques require expensive equipment such as specialized light sources, monochromators, tunable filters, calibrated photo-diodes, etc. The trade-offs between computational and physics-based characterization schemes are, however, not well understood. In this paper we perform an analysis of existing computational calibration schemes and elucidate their weak points. We highlight the limitations by comparing against ground truth measurements performed in an optical characterization laboratory (EMVA 1288 standard). Based on our analysis, we present accurate and affordable methods for the radiometric and spectral calibration of a camera.

  1. PHOTOMETRYPIPELINE: An automated pipeline for calibrated photometry

    NASA Astrophysics Data System (ADS)

    Mommert, M.

    2017-01-01

    PHOTOMETRYPIPELINE (PP) is an automated pipeline that produces calibrated photometry from imaging data through image registration, aperture photometry, photometric calibration, and target identification with only minimal human interaction. PP utilizes the widely used Source Extractor software for source identification and aperture photometry; SCAMP is used for image registration. Both image registration and photometric calibration are based on matching field stars with star catalogs, requiring catalog coverage of the respective field. A number of different astrometric and photometric catalogs can be queried online. Relying on a sufficient number of background stars for image registration and photometric calibration, PP is well-suited to analyze data from small to medium-sized telescopes. Calibrated magnitudes obtained by PP are typically accurate within ≤0.03 mag and astrometric accuracies are of the order of 0.3 arcsec relative to the catalogs used in the registration. The pipeline consists of an open-source software suite written in Python 2.7, can be run on Unix-based systems on a simple desktop machine, and is capable of realtime data analysis. PP has been developed for observations of moving targets, but can be used for analyzing point source observations of any kind.

  2. Photogrammetric camera calibration

    USGS Publications Warehouse

    Tayman, W.P.; Ziemann, H.

    1984-01-01

    Section 2 (Calibration) of the document "Recommended Procedures for Calibrating Photogrammetric Cameras and Related Optical Tests" from the International Archives of Photogrammetry, Vol. XIII, Part 4, is reviewed in the light of recent practical work, and suggestions for changes are made. These suggestions are intended as a basis for a further discussion. ?? 1984.

  3. OLI Radiometric Calibration

    NASA Technical Reports Server (NTRS)

    Markham, Brian; Morfitt, Ron; Kvaran, Geir; Biggar, Stuart; Leisso, Nathan; Czapla-Myers, Jeff

    2011-01-01

    Goals: (1) Present an overview of the pre-launch radiance, reflectance & uniformity calibration of the Operational Land Imager (OLI) (1a) Transfer to orbit/heliostat (1b) Linearity (2) Discuss on-orbit plans for radiance, reflectance and uniformity calibration of the OLI

  4. Calibration facility safety plan

    NASA Technical Reports Server (NTRS)

    Fastie, W. G.

    1971-01-01

    A set of requirements is presented to insure the highest practical standard of safety for the Apollo 17 Calibration Facility in terms of identifying all critical or catastrophic type hazard areas. Plans for either counteracting or eliminating these areas are presented. All functional operations in calibrating the ultraviolet spectrometer and the testing of its components are described.

  5. Sandia WIPP calibration traceability

    SciTech Connect

    Schuhen, M.D.; Dean, T.A.

    1996-05-01

    This report summarizes the work performed to establish calibration traceability for the instrumentation used by Sandia National Laboratories at the Waste Isolation Pilot Plant (WIPP) during testing from 1980-1985. Identifying the calibration traceability is an important part of establishing a pedigree for the data and is part of the qualification of existing data. In general, the requirement states that the calibration of Measuring and Test equipment must have a valid relationship to nationally recognized standards or the basis for the calibration must be documented. Sandia recognized that just establishing calibration traceability would not necessarily mean that all QA requirements were met during the certification of test instrumentation. To address this concern, the assessment was expanded to include various activities.

  6. Absolute Radiometric Calibration of EUNIS-06

    NASA Technical Reports Server (NTRS)

    Thomas, R. J.; Rabin, D. M.; Kent, B. J.; Paustian, W.

    2007-01-01

    The Extreme-Ultraviolet Normal-Incidence Spectrometer (EUNIS) is a soundingrocket payload that obtains imaged high-resolution spectra of individual solar features, providing information about the Sun's corona and upper transition region. Shortly after its successful initial flight last year, a complete end-to-end calibration was carried out to determine the instrument's absolute radiometric response over its Longwave bandpass of 300 - 370A. The measurements were done at the Rutherford-Appleton Laboratory (RAL) in England, using the same vacuum facility and EUV radiation source used in the pre-flight calibrations of both SOHO/CDS and Hinode/EIS, as well as in three post-flight calibrations of our SERTS sounding rocket payload, the precursor to EUNIS. The unique radiation source provided by the Physikalisch-Technische Bundesanstalt (PTB) had been calibrated to an absolute accuracy of 7% (l-sigma) at 12 wavelengths covering our bandpass directly against the Berlin electron storage ring BESSY, which is itself a primary radiometric source standard. Scans of the EUNIS aperture were made to determine the instrument's absolute spectral sensitivity to +- 25%, considering all sources of error, and demonstrate that EUNIS-06 was the most sensitive solar E W spectrometer yet flown. The results will be matched against prior calibrations which relied on combining measurements of individual optical components, and on comparisons with theoretically predicted 'insensitive' line ratios. Coordinated observations were made during the EUNIS-06 flight by SOHO/CDS and EIT that will allow re-calibrations of those instruments as well. In addition, future EUNIS flights will provide similar calibration updates for TRACE, Hinode/EIS, and STEREO/SECCHI/EUVI.

  7. Imager for Mars Pathfinder (IMP) image calibration

    USGS Publications Warehouse

    Reid, R.J.; Smith, P.H.; Lemmon, M.; Tanner, R.; Burkland, M.; Wegryn, E.; Weinberg, J.; Marcialis, R.; Britt, D.T.; Thomas, N.; Kramm, R.; Dummel, A.; Crowe, D.; Bos, B.J.; Bell, J.F.; Rueffer, P.; Gliem, F.; Johnson, J. R.; Maki, J.N.; Herkenhoff, K. E.; Singer, Robert B.

    1999-01-01

    The Imager for Mars Pathfinder returned over 16,000 high-quality images from the surface of Mars. The camera was well-calibrated in the laboratory, with <5% radiometric uncertainty. The photometric properties of two radiometric targets were also measured with 3% uncertainty. Several data sets acquired during the cruise and on Mars confirm that the system operated nominally throughout the course of the mission. Image calibration algorithms were developed for landed operations to correct instrumental sources of noise and to calibrate images relative to observations of the radiometric targets. The uncertainties associated with these algorithms as well as current improvements to image calibration are discussed. Copyright 1999 by the American Geophysical Union.

  8. Aerosol backscatter lidar calibration and data interpretation

    NASA Technical Reports Server (NTRS)

    Kavaya, M. J.; Menzies, R. T.

    1984-01-01

    A treatment of the various factors involved in lidar data acquisition and analysis is presented. This treatment highlights sources of fundamental, systematic, modeling, and calibration errors that may affect the accurate interpretation and calibration of lidar aerosol backscatter data. The discussion primarily pertains to ground based, pulsed CO2 lidars that probe the troposphere and are calibrated using large, hard calibration targets. However, a large part of the analysis is relevant to other types of lidar systems such as lidars operating at other wavelengths; continuous wave (CW) lidars; lidars operating in other regions of the atmosphere; lidars measuring nonaerosol elastic or inelastic backscatter; airborne or Earth-orbiting lidar platforms; and lidars employing combinations of the above characteristics.

  9. Automated calibration of a flight particle spectrometer

    NASA Technical Reports Server (NTRS)

    Torbert, Roy B.

    1986-01-01

    An automatic calibration system was designed for use in the vacuum facility at the Space Science Laboratory of the Marshall Space Flight Center. That system was developed and used in the intervening winter to calibrate the ion spectrometer that eventually flew in May 1986 aboard the NASA project, CRIT 1. During this summer, it is planned to implement the calibration of both an ion and electron spectrometer of a new design whose basic elements were conceived during the winter of 1985 to 1986. This spectrometer was completed in the summer and successfully mounted in the vacuum tank for calibration. However, the source gate valve malfunctioned, and, at the end of the summer, it still needed a replacement. During the inevitable delays in the experimental research, the numerical model of the Critical Velocity effect was completed and these results were presented.

  10. Visible/infrared radiometric calibration station

    SciTech Connect

    Byrd, D.A.; Maier, W.B. II; Bender, S.C.; Holland, R.F.; Michaud, F.D.; Luettgen, A.L.; Christensen, R.W.; O`Brian, T.R.

    1994-07-01

    We have begun construction of a visible/infrared radiometric calibration station that will allow for absolute calibration of optical and IR remote sensing instruments with clear apertures less than 16 inches in diameter in a vacuum environment. The calibration station broadband sources will be calibrated at the National Institute of Standards and Technology (NIST) and allow for traceable absolute radiometric calibration to within {plus_minus}3% in the visible and near IR (0.4--2.5 {mu}m), and less than {plus_minus}1% in the infrared, up to 12 {mu}m. Capabilities for placing diffraction limited images or for sensor full-field flooding will exist. The facility will also include the calibration of polarization and spectral effects, spatial resolution, field of view performance, and wavefront characterization. The configuration of the vacuum calibration station consists of an off-axis 21 inch, f/3.2, parabolic collimator with a scanning fold flat in collimated space. The sources are placed, via mechanisms to be described, at the focal plane of the off-axis parabola. Vacuum system pressure will be in the 10{sup {minus}6} Torr range. The broadband white-light source is a custom design by LANL with guidance from Labsphere Inc. The continuous operating radiance of the integrating sphere will be from 0.0--0.006 W/cm{sup 2}/Sr/{mu}m (upper level quoted for {approximately}500 nm wavelength). The blackbody source is also custom designed at LANL with guidance from NIST. The blackbody temperature will be controllable between 250--350{degrees}K. Both of the above sources have 4.1 inch apertures with estimated radiometric instability at less than 1%. The designs of each of these units will be described. The monochromator and interferometer light sources are outside the vacuum, but all optical relay and beam shaping optics are enclosed within the vacuum calibration station. These sources are described, as well as the methodology for alignment and characterization.

  11. Compact radiometric microwave calibrator

    SciTech Connect

    Fixsen, D. J.; Wollack, E. J.; Kogut, A.; Limon, M.; Mirel, P.; Singal, J.; Fixsen, S. M.

    2006-06-15

    The calibration methods for the ARCADE II instrument are described and the accuracy estimated. The Steelcast coated aluminum cones which comprise the calibrator have a low reflection while maintaining 94% of the absorber volume within 5 mK of the base temperature (modeled). The calibrator demonstrates an absorber with the active part less than one wavelength thick and only marginally larger than the mouth of the largest horn and yet black (less than -40 dB or 0.01% reflection) over five octaves in frequency.

  12. Dynamic Pressure Calibration Standard

    NASA Technical Reports Server (NTRS)

    Schutte, P. C.; Cate, K. H.; Young, S. D.

    1986-01-01

    Vibrating columns of fluid used to calibrate transducers. Dynamic pressure calibration standard developed for calibrating flush diaphragm-mounted pressure transducers. Pressures up to 20 kPa (3 psi) accurately generated over frequency range of 50 to 1,800 Hz. System includes two conically shaped aluminum columns one 5 cm (2 in.) high for low pressures and another 11 cm (4.3 in.) high for higher pressures, each filled with viscous fluid. Each column mounted on armature of vibration exciter, which imparts sinusoidally varying acceleration to fluid column. Signal noise low, and waveform highly dependent on quality of drive signal in vibration exciter.

  13. Airdata Measurement and Calibration

    NASA Technical Reports Server (NTRS)

    Haering, Edward A., Jr.

    1995-01-01

    This memorandum provides a brief introduction to airdata measurement and calibration. Readers will learn about typical test objectives, quantities to measure, and flight maneuvers and operations for calibration. The memorandum informs readers about tower-flyby, trailing cone, pacer, radar-tracking, and dynamic airdata calibration maneuvers. Readers will also begin to understand how some data analysis considerations and special airdata cases, including high-angle-of-attack flight, high-speed flight, and nonobtrusive sensors are handled. This memorandum is not intended to be all inclusive; this paper contains extensive reference and bibliography sections.

  14. Lidar Calibration Centre

    NASA Astrophysics Data System (ADS)

    Pappalardo, Gelsomina; Freudenthaler, Volker; Nicolae, Doina; Mona, Lucia; Belegante, Livio; D'Amico, Giuseppe

    2016-06-01

    This paper presents the newly established Lidar Calibration Centre, a distributed infrastructure in Europe, whose goal is to offer services for complete characterization and calibration of lidars and ceilometers. Mobile reference lidars, laboratories for testing and characterization of optics and electronics, facilities for inspection and debugging of instruments, as well as for training in good practices are open to users from the scientific community, operational services and private sector. The Lidar Calibration Centre offers support for trans-national access through the EC HORIZON2020 project ACTRIS-2.

  15. Calibration Fixture For Anemometer Probes

    NASA Technical Reports Server (NTRS)

    Lewis, Charles R.; Nagel, Robert T.

    1993-01-01

    Fixture facilitates calibration of three-dimensional sideflow thermal anemometer probes. With fixture, probe oriented at number of angles throughout its design range. Readings calibrated as function of orientation in airflow. Calibration repeatable and verifiable.

  16. The JMMC Evolutive Calibrator Selection Tool

    NASA Astrophysics Data System (ADS)

    Bonneau, D.; Clausse, J.-M.; Delfosse, X.; Duvert, G.; Borde, P.; Mourard, D.; Berio, P.; Cruzalebes, P.

    2004-12-01

    In stellar interferometry, the raw fringe visibilities must calibrated to obtain the true visibilities and then observables which can be interpreted as astrophysical parameters. The selection of suitable calibration stars is crucial to obtain the ultimate precision of the interferometric instruments like VLTI. The calibrators must have spectro-photometric properties and sky location close to those of the scientific target. The smaller the calibrators the lesser the sensibility of the angular diameter determination to their intrinsic visibility or sources of instabilities. So, we have developed , we have adopted a method of ?virtual the observatory? type to create an evolutive catalog of stars giving all the useful informations for the selection of calibrators with respect to the requirements of the astrophysical program. The list of possible calibrators is obtained from a set of catalogs available at the Centre de Données astronomiques de Strasbourg (CDS). The CDS request is based on some criteria like angular distance and magnitude around the scientific target. For each star, the squared visibility is computed as function of the wavelength, the maximum baseline and the value of the angular diameter (measured or computed from the colors or spectral type). The accuracy of this visibility of possible calibrators must satisfy constraints fixed by the expected accuracy of the scientific objet visibility and the instrumental configuration. It is possible to refine the choice of the calibrators using selection criteria (sky position, magnitude difference, spectral type, variability and multiplicity). This calibrator selection tool is integrated to ASPRO the interferometric observing preparation software developed by the JMMC.

  17. Calibration of a Thomson scattering diagnostic for fluctuation measurements

    SciTech Connect

    Stephens, H. D.; Borchardt, M. T.; Den Hartog, D. J.; Falkowski, A. F.; Holly, D. J.; O'Connell, R.; Reusch, J. A.

    2008-10-15

    Detailed calibrations of the Madison Symmetric Torus polychromator Thomson scattering system have been made suitable for electron temperature fluctuation measurements. All calibrations have taken place focusing on accuracy, ease of use and repeatability, and in situ measurements wherever possible. Novel calibration processes have been made possible with an insertable integrating sphere (ISIS), using an avalanche photodiode (APD) as a reference detector and optical parametric oscillator (OPO). Discussed are a novel in situ spatial calibration with the use of the ISIS, the use of an APD as a reference detector to streamline the APD calibration process, a standard dc spectral calibration, and in situ pulsed spectral calibration made possible with a combination of an OPO as a light source, the ISIS, and an APD used as a reference detector. In addition a relative quantum efficiency curve for the APDs is obtained to aid in uncertainty analysis.

  18. Method and apparatus for calibrating a particle emissions monitor

    DOEpatents

    Flower, William L.; Renzi, Ronald F.

    1998-07-07

    The instant invention discloses method and apparatus for calibrating particulate emissions monitors, in particular, and sampling probes, in general, without removing the instrument from the system being monitored. A source of one or more specific metals in aerosol (either solid or liquid) or vapor form is housed in the instrument. The calibration operation is initiated by moving a focusing lens, used to focus a light beam onto an analysis location and collect the output light response, from an operating position to a calibration position such that the focal point of the focusing lens is now within a calibration stream issuing from a calibration source. The output light response from the calibration stream can be compared to that derived from an analysis location in the operating position to more accurately monitor emissions within the emissions flow stream.

  19. Method and apparatus for calibrating a particle emissions monitor

    DOEpatents

    Flower, W.L.; Renzi, R.F.

    1998-07-07

    The invention discloses a method and apparatus for calibrating particulate emissions monitors, in particular, sampling probes, and in general, without removing the instrument from the system being monitored. A source of one or more specific metals in aerosol (either solid or liquid) or vapor form is housed in the instrument. The calibration operation is initiated by moving a focusing lens, used to focus a light beam onto an analysis location and collect the output light response, from an operating position to a calibration position such that the focal point of the focusing lens is now within a calibration stream issuing from a calibration source. The output light response from the calibration stream can be compared to that derived from an analysis location in the operating position to more accurately monitor emissions within the emissions flow stream. 6 figs.

  20. Ophthalmic applicators: an overview of calibrations following the change to SI units.

    PubMed

    Holmes, Shannon M; Micka, John A; DeWerd, Larry A

    2009-05-01

    Since the NIST dose to water standard for 90Sr/90Y ophthalmic applicators was introduced, numerous sources have undergone calibration either at NIST or at the University of Wisconsin Accredited Dosimetry Calibration Laboratory (UWADCL). From 1997 to 2008, 222 of these beta-emitting sources were calibrated at the UWADCL, and prior reference source strength values were available for 149 of these sources. A survey of UWADCL ophthalmic applicator calibrations is presented here, demonstrating an average discrepancy of -19% with a standard deviation of +/- 16% between prior reference values and the NIST-traceable UWADCL absorbed dose to water calibrations. Values ranged from -49% to +42%.

  1. Roundness calibration standard

    DOEpatents

    Burrus, Brice M.

    1984-01-01

    A roundness calibration standard is provided with a first arc constituting the major portion of a circle and a second arc lying between the remainder of the circle and the chord extending between the ends of said first arc.

  2. Traceable Pyrgeometer Calibrations

    SciTech Connect

    Dooraghi, Mike; Kutchenreiter, Mark; Reda, Ibrahim; Habte, Aron; Sengupta, Manajit; Andreas, Afshin; Newman, Martina; Webb, Craig

    2016-05-02

    This presentation provides a high-level overview of the progress on the Broadband Outdoor Radiometer Calibrations for all shortwave and longwave radiometers that are deployed by the Atmospheric Radiation Measurement program.

  3. Auroral meridian scanning photometer calibration using Jupiter

    NASA Astrophysics Data System (ADS)

    Jackel, Brian J.; Unick, Craig; Creutzberg, Fokke; Baker, Greg; Davis, Eric; Donovan, Eric F.; Connors, Martin; Wilson, Cody; Little, Jarrett; Greffen, M.; McGuffin, Neil

    2016-10-01

    Observations of astronomical sources provide information that can significantly enhance the utility of auroral data for scientific studies. This report presents results obtained by using Jupiter for field cross calibration of four multispectral auroral meridian scanning photometers during the 2011-2015 Northern Hemisphere winters. Seasonal average optical field-of-view and local orientation estimates are obtained with uncertainties of 0.01 and 0.1°, respectively. Estimates of absolute sensitivity are repeatable to roughly 5 % from one month to the next, while the relative response between different wavelength channels is stable to better than 1 %. Astronomical field calibrations and darkroom calibration differences are on the order of 10 %. Atmospheric variability is the primary source of uncertainty; this may be reduced with complementary data from co-located instruments.

  4. U.S. Department of Energy Office of Legacy Management Calibration Facilities - 12103

    SciTech Connect

    Barr, Deborah; Traub, David; Widdop, Michael

    2012-07-01

    This paper describes radiometric calibration facilities located in Grand Junction, Colorado, and at three secondary calibration sites. These facilities are available to the public for the calibration of radiometric field instrumentation for in-situ measurements of radium (uranium), thorium, and potassium. Both borehole and hand-held instruments may be calibrated at the facilities. Aircraft or vehicle mounted systems for large area surveys may be calibrated at the Grand Junction Regional Airport facility. These calibration models are recognized internationally as stable, well-characterized radiation sources for calibration. Calibration models built in other countries are referenced to the DOE models, which are also widely used as a standard for calibration within the U.S. Calibration models are used to calibrate radiation detectors used in uranium exploration, remediation, and homeland security. (authors)

  5. Uses of Continuum Radiation in the AXAF Calibration

    NASA Technical Reports Server (NTRS)

    Kolodziejczak, J. J.; Austin, R. A.; Eisner, R. F.; ODell, S. L.; Sulkanen, M. E.; Swartz, D. A.; Tennant, A. F.; Weisskopf, M. C.; Zirnstein, G.; McDermott, W. C.

    1997-01-01

    X-ray calibration of the Advanced X-ray Astrophysics Facility (AXAF) observatory at the MSFC X-Ray Calibration Facility (XRCF) made novel use of the x-ray continuum from a conventional electron-impact source. Taking advantage of the good spectral resolution of solid-state detectors, continuum measurements proved advantageous in calibrating the effective area of AXAF's High-Resolution Mirror Assembly (HRMA) and in verifying its alignment to the XRCF's optical axis.

  6. Progress Report of CNES Activities Regarding the Absolute Calibration Method

    DTIC Science & Technology

    2010-11-01

    several receivers (Ashtech Z12-T, Septentrio PolaRx2, and Dicom GTR50) and a GNSS signal simulator (Spirent 4760) according to the temperature and...laboratories, Ashtech Z12- T, Septentrio PolaRx2, and Dicom GTR50, can be calibrated with the absolute method [6,8]. The last works concerned the...Ashtech, Septentrio, and Dicom receiver calibrations. Table 2. Uncertainty of the different receiver calibrations. Uncertainty Source

  7. Calibration of Speed Enforcement Down-The-Road Radars.

    PubMed

    Jendzurski, John; Paulter, Nicholas G

    2009-01-01

    We examine the measurement uncertainty associated with different methods of calibrating the ubiquitous down-the-road (DTR) radar used in speed enforcement. These calibration methods include the use of audio frequency sources, tuning forks, a fifth wheel attached to the rear of the vehicle with the radar unit, and the speedometer of the vehicle. We also provide an analysis showing the effect of calibration uncertainty on DTR-radar speed measurement uncertainty.

  8. Simple transfer calibration method for a Cimel Sun-Moon photometer: calculating lunar calibration coefficients from Sun calibration constants.

    PubMed

    Li, Zhengqiang; Li, Kaitao; Li, Donghui; Yang, Jiuchun; Xu, Hua; Goloub, Philippe; Victori, Stephane

    2016-09-20

    The Cimel new technologies allow both daytime and nighttime aerosol optical depth (AOD) measurements. Although the daytime AOD calibration protocols are well established, accurate and simple nighttime calibration is still a challenging task. Standard lunar-Langley and intercomparison calibration methods both require specific conditions in terms of atmospheric stability and site condition. Additionally, the lunar irradiance model also has some known limits on its uncertainty. This paper presents a simple calibration method that transfers the direct-Sun calibration constant, V0,Sun, to the lunar irradiance calibration coefficient, CMoon. Our approach is a pure calculation method, independent of site limits, e.g., Moon phase. The method is also not affected by the lunar irradiance model limitations, which is the largest error source of traditional calibration methods. Besides, this new transfer calibration approach is easy to use in the field since CMoon can be obtained directly once V0,Sun is known. Error analysis suggests that the average uncertainty of CMoon over the 440-1640 nm bands obtained with the transfer method is 2.4%-2.8%, depending on the V0,Sun approach (Langley or intercomparison), which is comparable with that of lunar-Langley approach, theoretically. In this paper, the Sun-Moon transfer and the Langley methods are compared based on site measurements in Beijing, and the day-night measurement continuity and performance are analyzed.

  9. [Study on the absolute spectral irradiation calibration method for far ultraviolet spectrometer in remote sensing].

    PubMed

    Yu, Lei; Lin, Guan-Yu; Chen, Bin

    2013-01-01

    The present paper studied spectral irradiation responsivities calibration method which can be applied to the far ultraviolet spectrometer for upper atmosphere remote sensing. It is difficult to realize the calibration for far ultraviolet spectrometer for many reasons. Standard instruments for far ultraviolet waveband calibration are few, the degree of the vacuum experiment system is required to be high, the stabilities of the experiment are hardly maintained, and the limitation of the far ultraviolet waveband makes traditional diffuser and the integrating sphere radiance calibration method difficult to be used. To solve these problems, a new absolute spectral irradiance calibration method was studied, which can be applied to the far ultraviolet calibration. We build a corresponding special vacuum experiment system to verify the calibration method. The light source system consists of a calibrated deuterium lamp, a vacuum ultraviolet monochromater and a collimating system. We used the calibrated detector to obtain the irradiance responsivities of it. The three instruments compose the calibration irradiance source. We used the "calibration irradiance source" to illuminate the spectrometer prototype and obtained the spectral irradiance responsivities. It realized the absolute spectral irradiance calibration for the far ultraviolet spectrometer utilizing the calibrated detector. The absolute uncertainty of the calibration is 7.7%. The method is significant for the ground irradiation calibration of the far ultraviolet spectrometer in upper atmosphere remote sensing.

  10. Integrated calibration sphere and calibration step fixture for improved coordinate measurement machine calibration

    DOEpatents

    Clifford, Harry J [Los Alamos, NM

    2011-03-22

    A method and apparatus for mounting a calibration sphere to a calibration fixture for Coordinate Measurement Machine (CMM) calibration and qualification is described, decreasing the time required for such qualification, thus allowing the CMM to be used more productively. A number of embodiments are disclosed that allow for new and retrofit manufacture to perform as integrated calibration sphere and calibration fixture devices. This invention renders unnecessary the removal of a calibration sphere prior to CMM measurement of calibration features on calibration fixtures, thereby greatly reducing the time spent qualifying a CMM.

  11. DESIGN NOTE: Reduction of uncertainties in temperature calibrations by comparison

    NASA Astrophysics Data System (ADS)

    Drnovsek, Janko; Pusnik, Igor; Bojkovski, Jovan

    1998-11-01

    The objective of this design note is to discuss and define the total uncertainty in temperature calibrations by comparison, by analysing most of the likely error sources. As a result of the proposed and developed uncertainty analysis, further reductions of uncertainties could be realized if/when better equipment becomes available. The analysis is performed as a case study using state-of-the-art calibration equipment described in the design note. This equipment is located in the authors' own secondary temperature calibration laboratory. Accreditation for this laboratory has been granted through The Dutch Council of Accreditation (RVA) for calibrations in the temperature range -55 to 0957-0233/9/11/017/img1C. In temperature calibrations by comparison the four main groups of uncertainties are the reproducibility, uncertainty of a reference thermometer, uncertainty of a calibration bath or a furnace and uncertainty of a measuring device. Special care is taken, using a thorough evaluation procedure, to ensure that the uncertainty contribution of the calibration bath or furnace is as low as possible. This is necessary because the total uncertainty assigned to an instrument under calibration is larger than the largest individual uncertainty contribution. In temperature calibrations the largest uncertainty is most likely to be the uncertainty of the calibration bath or a furnace. Therefore this uncertainty typically represents the lowest limit for further reduction of the total uncertainty of the calibration process. The analysis performed allows optimal use of temperature calibration equipment for calibration of thermometers by comparison. In this way most practical calibration needs are satisfied in a more economical way than by using substantially more expensive fixed point calibrations.

  12. PHOTOMETRYPIPELINE - An Automated Pipeline for Calibrated Photometry

    NASA Astrophysics Data System (ADS)

    Mommert, Michael; Moskovitz, Nicholas; Trilling, David E.

    2016-10-01

    Telescopes acquire massive amounts of imaging data every night. The goal of a large fraction of these observations is to obtain calibrated photometry for point sources - stars or moving Solar System targets - in different filters.We present PHOTOMETRYPIPELINE (PP, github.com/mommermi/photometrypipeline), an automated pipeline to obtain calibrated photometry from imaging data. PP is an open-source Python 2.7 software suite that provides image registration, aperture photometry, photometric calibration, and target identification with only minimal human interaction. For image registration, PP utilizes Source Extractor (Bertin & Arnouts 1996, A&AS, 117) and SWARP (Bertin et al. 2002, ASP Conf. S., 228) to find a plate solution for each frame, providing accurate target astrometry. Circular aperture photometry is performed using Source Extractor; an optimum aperture radius is identified using a curve-of-growth analysis. Photometric calibration is obtained through matching the background source catalog with star catalogs with reliable photometry (e.g., SDSS, URAT-1) in an iterative process; magnitude zeropoint accuracies are usually of the order of 0.03 mag, or better. Final calibrated photometry for each field source is written into a queriable database; target photometry is extracted from this database. Moving targets are identified using JPL Horizons (Giorgini et al. 1996, BAAS, 28) ephemerides. Image combination capabilities (using SWARP, Bertin 2006, ASP Conf. S., 112) are also available to improve the target's signal.PP is well-suited for data covering a few square arcminutes of the sky due to its dependence on background sources for registration and calibration. PP can be run on Unix-based systems on a simple desktop machine and is capable of realtime data analysis. PP has been developed for observations of moving targets, but can also be used on other observations. Efforts to improve the sky coverage for phometric calibration are in progress. Also, a module will be

  13. Calibration plan for the sea and land surface temperature radiometer

    NASA Astrophysics Data System (ADS)

    Smith, David L.; Nightingale, Tim J.; Mortimer, Hugh; Middleton, Kevin; Edeson, Ruben; Cox, Caroline V.; Mutlow, Chris T.; Maddison, Brian J.

    2013-10-01

    The Sea and Land Surface Temperature Radiometer (SLSTR) to be flown on ESA's Sentinel-3 mission is a multichannel scanning radiometer that will continue the 21-year datasets of the Along Track Scanning Radiometer (ATSR) series. As its name implies, measurements from SLSTR will be used to retrieve global sea surface temperatures to an uncertainty of <0.3K traced to international standards. To achieve these low uncertainties requires an end to end instrument calibration strategy that includes pre-launch calibration at subsystem and instrument level, on-board calibration systems and sustained post launch activities. The authors describe the preparations for the pre-launch calibration activities including the spectral response, instrument level alignment tests, solar and infrared radiometric calibration. A purpose built calibration rig has been designed and built at RAL space that will accommodate the SLSTR instrument, infrared calibration sources and alignment equipment. The calibration rig has been commissioned and results of these tests will be presented. Finally the authors will present the planning for the on-orbit monitoring and calibration activities to ensure that calibration is maintained. These activities include vicarious calibration techniques that have been developed through previous missions, and the deployment of ship-borne radiometers.

  14. Polarimetric Palsar Calibration

    NASA Astrophysics Data System (ADS)

    Touzi, R.; Shimada, M.

    2008-11-01

    Polarimetric PALSAR system parameters are assessed using data sets collected over various calibration sites. The data collected over the Amazonian forest permits validating the zero Faraday rotation hypotheses near the equator. The analysis of the Amazonian forest data and the response of the corner reflectors deployed during the PALSAR acquisitions lead to the conclusion that the antenna is highly isolated (better than -35 dB). Theses results are confirmed using data collected over the Sweden and Ottawa calibration sites. The 5-m height trihedrals deployed in the Sweden calibration site by the Chalmers University of technology permits accurate measurement of antenna parameters, and detection of 2-3 degree Faraday rotation during day acquisition, whereas no Faraday rotation was noted during night acquisition. Small Faraday rotation angles (2-3 degree) have been measured using acquisitions over the DLR Oberpfaffenhofen and the Ottawa calibration sites. The presence of small but still significant Faraday rotation (2-3 degree) induces a CR return at the cross-polarization HV and VH that should not be interpreted as the actual antenna cross-talk. PALSAR antenna is highly isolated (better than -35 dB), and diagonal antenna distortion matrices (with zero cross-talk terms) can be used for accurate calibration of PALSAR polarimetric data.

  15. STIS Calibration Pipeline

    NASA Astrophysics Data System (ADS)

    Hulbert, S.; Hodge, P.; Lindler, D.; Shaw, R.; Goudfrooij, P.; Katsanis, R.; Keener, S.; McGrath, M.; Bohlin, R.; Baum, S.

    1997-05-01

    Routine calibration of STIS observations in the HST data pipeline is performed by the CALSTIS task. CALSTIS can: subtract the over-scan region and a bias image from CCD observations; remove cosmic ray features from CCD observations; correct global nonlinearities for MAMA observations; subtract a dark image; and, apply flat field corrections. In the case of spectral data, CALSTIS can also: assign a wavelength to each pixel; apply a heliocentric correction to the wavelengths; convert counts to absolute flux; process the automatically generated spectral calibration lamp observations to improve the wavelength solution; rectify two-dimensional (longslit) spectra; subtract interorder and sky background; and, extract one-dimensional spectra. CALSTIS differs in significant ways from the current HST calibration tasks. The new code is written in ANSI C and makes use of a new C interface to IRAF. The input data, reference data, and output calibrated data are all in FITS format, using IMAGE or BINTABLE extensions. Error estimates are computed and include contributions from the reference images. The entire calibration can be performed by one task, but many steps can also be performed individually.

  16. Psychophysical contrast calibration

    PubMed Central

    To, Long; Woods, Russell L; Goldstein, Robert B; Peli, Eli

    2013-01-01

    Electronic displays and computer systems offer numerous advantages for clinical vision testing. Laboratory and clinical measurements of various functions and in particular of (letter) contrast sensitivity require accurately calibrated display contrast. In the laboratory this is achieved using expensive light meters. We developed and evaluated a novel method that uses only psychophysical responses of a person with normal vision to calibrate the luminance contrast of displays for experimental and clinical applications. Our method combines psychophysical techniques (1) for detection (and thus elimination or reduction) of display saturating nonlinearities; (2) for luminance (gamma function) estimation and linearization without use of a photometer; and (3) to measure without a photometer the luminance ratios of the display’s three color channels that are used in a bit-stealing procedure to expand the luminance resolution of the display. Using a photometer we verified that the calibration achieved with this procedure is accurate for both LCD and CRT displays enabling testing of letter contrast sensitivity to 0.5%. Our visual calibration procedure enables clinical, internet and home implementation and calibration verification of electronic contrast testing. PMID:23643843

  17. Calibration Under Uncertainty.

    SciTech Connect

    Swiler, Laura Painton; Trucano, Timothy Guy

    2005-03-01

    This report is a white paper summarizing the literature and different approaches to the problem of calibrating computer model parameters in the face of model uncertainty. Model calibration is often formulated as finding the parameters that minimize the squared difference between the model-computed data (the predicted data) and the actual experimental data. This approach does not allow for explicit treatment of uncertainty or error in the model itself: the model is considered the %22true%22 deterministic representation of reality. While this approach does have utility, it is far from an accurate mathematical treatment of the true model calibration problem in which both the computed data and experimental data have error bars. This year, we examined methods to perform calibration accounting for the error in both the computer model and the data, as well as improving our understanding of its meaning for model predictability. We call this approach Calibration under Uncertainty (CUU). This talk presents our current thinking on CUU. We outline some current approaches in the literature, and discuss the Bayesian approach to CUU in detail.

  18. Calibration Systems Final Report

    SciTech Connect

    Myers, Tanya L.; Broocks, Bryan T.; Phillips, Mark C.

    2006-02-01

    The Calibration Systems project at Pacific Northwest National Laboratory (PNNL) is aimed towards developing and demonstrating compact Quantum Cascade (QC) laser-based calibration systems for infrared imaging systems. These on-board systems will improve the calibration technology for passive sensors, which enable stand-off detection for the proliferation or use of weapons of mass destruction, by replacing on-board blackbodies with QC laser-based systems. This alternative technology can minimize the impact on instrument size and weight while improving the quality of instruments for a variety of missions. The potential of replacing flight blackbodies is made feasible by the high output, stability, and repeatability of the QC laser spectral radiance.

  19. Magnetic Test Facility - Sensor and Coil Calibrations

    DTIC Science & Technology

    2013-08-01

    RF ) source, which is used to release excited elec- trons from their high energy state; this is achieved via a...3.2 Simulation Fi gu re 3. 15 :R ep re se nt at io n of B y ,B z an d B x fie ld s co m po ne nt s m ap pe d in th e yz -p la ne at x = 0, fo rt he EL...sensor calibration, but also calibration of the excitation coils used within the magnetic test system. Reduction of external noise influences

  20. Field calibration of reference reflectance panels

    NASA Technical Reports Server (NTRS)

    Jackson, Ray D.; Moran, M. Susan; Slater, Philip N.; Biggar, Stuart F.

    1987-01-01

    A procedure for calibrating reference reflectance panels using the sun as the radiation source and a pressed-polytetrafluoroethylene powder standard is described. The directional/directional reflectance factor and the directional/hemispheric reflectance factor are examined. Directional/directional voltage responses for pressed-halon are analyzed. Three painted BaSO4 and one painted halon were calibrated using the proposed procedure. The effects of diffuse irradiance on reflectance-factor measurements are investigated. It is determined that the method has an accuracy on the order of 1 percent. The advantages and disadvantages of this method are discussed.

  1. Calibrating the Tree of Life: fossils, molecules and evolutionary timescales

    PubMed Central

    Forest, Félix

    2009-01-01

    Background Molecular dating has gained ever-increasing interest since the molecular clock hypothesis was proposed in the 1960s. Molecular dating provides detailed temporal frameworks for divergence events in phylogenetic trees, allowing diverse evolutionary questions to be addressed. The key aspect of the molecular clock hypothesis, namely that differences in DNA or protein sequence between two species are proportional to the time elapsed since they diverged, was soon shown to be untenable. Other approaches were proposed to take into account rate heterogeneity among lineages, but the calibration process, by which relative times are transformed into absolute ages, has received little attention until recently. New methods have now been proposed to resolve potential sources of error associated with the calibration of phylogenetic trees, particularly those involving use of the fossil record. Scope and Conclusions The use of the fossil record as a source of independent information in the calibration process is the main focus of this paper; other sources of calibration information are also discussed. Particularly error-prone aspects of fossil calibration are identified, such as fossil dating, the phylogenetic placement of the fossil and the incompleteness of the fossil record. Methods proposed to tackle one or more of these potential error sources are discussed (e.g. fossil cross-validation, prior distribution of calibration points and confidence intervals on the fossil record). In conclusion, the fossil record remains the most reliable source of information for the calibration of phylogenetic trees, although associated assumptions and potential bias must be taken into account. PMID:19666901

  2. Iterative Magnetometer Calibration

    NASA Technical Reports Server (NTRS)

    Sedlak, Joseph

    2006-01-01

    This paper presents an iterative method for three-axis magnetometer (TAM) calibration that makes use of three existing utilities recently incorporated into the attitude ground support system used at NASA's Goddard Space Flight Center. The method combines attitude-independent and attitude-dependent calibration algorithms with a new spinning spacecraft Kalman filter to solve for biases, scale factors, nonorthogonal corrections to the alignment, and the orthogonal sensor alignment. The method is particularly well-suited to spin-stabilized spacecraft, but may also be useful for three-axis stabilized missions given sufficient data to provide observability.

  3. Photometric Calibration of Consumer Video Cameras

    NASA Technical Reports Server (NTRS)

    Suggs, Robert; Swift, Wesley, Jr.

    2007-01-01

    Equipment and techniques have been developed to implement a method of photometric calibration of consumer video cameras for imaging of objects that are sufficiently narrow or sufficiently distant to be optically equivalent to point or line sources. Heretofore, it has been difficult to calibrate consumer video cameras, especially in cases of image saturation, because they exhibit nonlinear responses with dynamic ranges much smaller than those of scientific-grade video cameras. The present method not only takes this difficulty in stride but also makes it possible to extend effective dynamic ranges to several powers of ten beyond saturation levels. The method will likely be primarily useful in astronomical photometry. There are also potential commercial applications in medical and industrial imaging of point or line sources in the presence of saturation.This development was prompted by the need to measure brightnesses of debris in amateur video images of the breakup of the Space Shuttle Columbia. The purpose of these measurements is to use the brightness values to estimate relative masses of debris objects. In most of the images, the brightness of the main body of Columbia was found to exceed the dynamic ranges of the cameras. A similar problem arose a few years ago in the analysis of video images of Leonid meteors. The present method is a refined version of the calibration method developed to solve the Leonid calibration problem. In this method, one performs an endto- end calibration of the entire imaging system, including not only the imaging optics and imaging photodetector array but also analog tape recording and playback equipment (if used) and any frame grabber or other analog-to-digital converter (if used). To automatically incorporate the effects of nonlinearity and any other distortions into the calibration, the calibration images are processed in precisely the same manner as are the images of meteors, space-shuttle debris, or other objects that one seeks to

  4. Three-point bridge calibration with one resistor

    NASA Technical Reports Server (NTRS)

    Harrison, D. R.; Brown, R. M.

    1974-01-01

    Method calibrates transducer bridge curing unbalanced condition and line resistance errors are negligible. Series resistance method can be automated easily and controlled by 2-bit information source which provide 4 states for switches.

  5. SWAT Model Configuration, Calibration and Validation for Lake Champlain Basin

    EPA Pesticide Factsheets

    The Soil and Water Assessment Tool (SWAT) model was used to develop phosphorus loading estimates for sources in the Lake Champlain Basin. This document describes the model setup and parameterization, and presents calibration results.

  6. Technique for Radiometer and Antenna Array Calibration - TRAAC

    NASA Technical Reports Server (NTRS)

    Meyer, Paul; Sims, William; Varnavas, Kosta; McCracken, Jeff; Srinivasan, Karthik; Limaye, Ashutosh; Laymon, Charles; Richeson. James

    2012-01-01

    Highly sensitive receivers are used to detect minute amounts of emitted electromagnetic energy. Calibration of these receivers is vital to the accuracy of the measurements. Traditional calibration techniques depend on calibration reference internal to the receivers as reference for the calibration of the observed electromagnetic energy. Such methods can only calibrate errors in measurement introduced by the receiver only. The disadvantage of these existing methods is that they cannot account for errors introduced by devices, such as antennas, used for capturing electromagnetic radiation. This severely limits the types of antennas that can be used to make measurements with a high degree of accuracy. Complex antenna systems, such as electronically steerable antennas (also known as phased arrays), while offering potentially significant advantages, suffer from a lack of a reliable and accurate calibration technique. The proximity of antenna elements in an array results in interaction between the electromagnetic fields radiated (or received) by the individual elements. This phenomenon is called mutual coupling. The new calibration method uses a known noise source as a calibration load to determine the instantaneous characteristics of the antenna. The noise source is emitted from one element of the antenna array and received by all the other elements due to mutual coupling. This received noise is used as a calibration standard to monitor the stability of the antenna electronics.

  7. Study of laser energy standard and establishment of calibration device

    NASA Astrophysics Data System (ADS)

    Xia, Ming; Gao, Jianqiang; Xia, Junwen; Yin, Dejin; Li, Tiecheng; Zhang, Dong

    2016-10-01

    This paper studied the standard laser energy meter. A self calibration of the thermoelectric type standard laser energy meter is developed, which is provided with a suitable electric heater. It can be used to simulate and replace the equivalent thermal effect, and to realize the absolute measurement of the laser energy. Because the standard laser energy meter can bulk absorb laser radiation, it can bear higher laser energy density. The material absorption spectrum of the standard laser energy meter is relatively flat from the ultraviolet to the infrared, so it can be used for the measurement of laser energy at any wavelength. In addition, an electric calibration instrument is developed. The electric calibration instrument can be directly displayed or synchronous display by the digital frequency meter. The laser energy calibration device is composed of standard laser energy meter, pulsed laser source, monitoring system, digital multi meter and complete set of electric calibration system. Laser energy calibration device uses split beam detection method. The laser is divided into two beams by means of a wedge shaped optical beam splitter. A laser energy meter is used to monitor the change of the reflected light to reduce the influence of the output laser energy stability of the pulsed laser source, thereby improving the uncertainty of the calibration result. The sensitivity, correction factor and indication error of the laser energy meter can be calibrated by using the standard laser energy meter and the under calibrated laser energy meter to measure the transmission laser beam.

  8. Multimodal spatial calibration for accurately registering EEG sensor positions.

    PubMed

    Zhang, Jianhua; Chen, Jian; Chen, Shengyong; Xiao, Gang; Li, Xiaoli

    2014-01-01

    This paper proposes a fast and accurate calibration method to calibrate multiple multimodal sensors using a novel photogrammetry system for fast localization of EEG sensors. The EEG sensors are placed on human head and multimodal sensors are installed around the head to simultaneously obtain all EEG sensor positions. A multiple views' calibration process is implemented to obtain the transformations of multiple views. We first develop an efficient local repair algorithm to improve the depth map, and then a special calibration body is designed. Based on them, accurate and robust calibration results can be achieved. We evaluate the proposed method by corners of a chessboard calibration plate. Experimental results demonstrate that the proposed method can achieve good performance, which can be further applied to EEG source localization applications on human brain.

  9. Radioxenon detector calibration spike production and delivery systems

    SciTech Connect

    Foxe, Michael P.; Cameron, Ian M.; Cooper, Matthew W.; Haas, Derek A.; Hayes, James C.; Kriss, Aaron A.; Lidey, Lance S.; Mendez, Jennifer M.; Prinke, Amanda M.; Riedmann, Robin A.

    2016-03-01

    Abstract Beta-Gamma coincidence radioxenon detectors must be calibrated for each of the four-radioxenon isotopes (135Xe, 133Xe, 133mXe, and 131mXe). Without a proper calibration, there is potential for the misidentification of the amount of each isotope detected. It is important to accurately determine the amount of each radioxenon isotope, as the ratios can be used to distinguish between an anthropogenic source and a nuclear explosion. We have developed a xenon calibration system (XeCalS) that produces calibration spikes of known activity and pressure for field calibration of detectors. The activity concentrations of these calibration spikes are measured using a beta-gamma coincidence detector and a high purity germanium (HPGe) detector. We will present the results from the development and commissioning of XeCalS, along with the future plans for a portable spike implementation system.

  10. Preparation of enzyme calibration materials.

    PubMed

    Férard, G; Lessinger, J M

    1998-12-01

    Standardisation in clinical enzymology needs not only reference methods but also reference materials. While single-enzyme reference enzymes have been developed, a multienzyme certified reference material (MECRM) available in high amount remains to be produced. To transfer trueness from the value of the reference system to patients' results, validated enzyme calibrators (EC) are also needed. Both the MECRM and the ECs must exhibit the same catalytic properties as the corresponding enzymes in human plasma. Moreover, commutability of these materials with patients' samples must be experimentally tested for one or a set of methods defined by an analytical specificity equal to that of the reference method. Various experimental studies have shown that the commutability of an enzyme material depends on the source of enzyme and its purification process, the matrix (including cofactors, effectors, additives, stabilisers... ) and the mode of processing of the final material. To promote intermethod calibration in clinical enzymology, a collaborative programme between the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC), Institute for Reference Materials and Measurements (IRMM, Geel, Belgium) and IFCC corporate members is in progress for the development of a MECRM containing amylase, ALT, AST, ALP, CK, GGT, LDH, and lipase and exhibiting a wide and defined commutability.

  11. Calibrating Communication Competencies

    NASA Astrophysics Data System (ADS)

    Surges Tatum, Donna

    2016-11-01

    The Many-faceted Rasch measurement model is used in the creation of a diagnostic instrument by which communication competencies can be calibrated, the severity of observers/raters can be determined, the ability of speakers measured, and comparisons made between various groups.

  12. TWSTFT Link Calibration Report

    DTIC Science & Technology

    2015-09-01

    Serrano, G. Brunetti (2013) Relative Calibration of the Time Transfer Link between CERN and LNGS for Precise Neutrino Time of Flight Measurements. Proc...Esteban, M. Pallavicini, Va. Pettiti, C. Plantard, A. Razeto (2012) Measurement of CNGS Muon Neutrinos Speed with Borexino: INRIM and ROA Contribution

  13. Computerized tomography calibrator

    NASA Technical Reports Server (NTRS)

    Engel, Herbert P. (Inventor)

    1991-01-01

    A set of interchangeable pieces comprising a computerized tomography calibrator, and a method of use thereof, permits focusing of a computerized tomographic (CT) system. The interchangeable pieces include a plurality of nestable, generally planar mother rings, adapted for the receipt of planar inserts of predetermined sizes, and of predetermined material densities. The inserts further define openings therein for receipt of plural sub-inserts. All pieces are of known sizes and densities, permitting the assembling of different configurations of materials of known sizes and combinations of densities, for calibration (i.e., focusing) of a computerized tomographic system through variation of operating variables thereof. Rather than serving as a phanton, which is intended to be representative of a particular workpiece to be tested, the set of interchangeable pieces permits simple and easy standardized calibration of a CT system. The calibrator and its related method of use further includes use of air or of particular fluids for filling various openings, as part of a selected configuration of the set of pieces.

  14. Improved Regression Calibration

    ERIC Educational Resources Information Center

    Skrondal, Anders; Kuha, Jouni

    2012-01-01

    The likelihood for generalized linear models with covariate measurement error cannot in general be expressed in closed form, which makes maximum likelihood estimation taxing. A popular alternative is regression calibration which is computationally efficient at the cost of inconsistent estimation. We propose an improved regression calibration…

  15. Commodity-Free Calibration

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Commodity-free calibration is a reaction rate calibration technique that does not require the addition of any commodities. This technique is a specific form of the reaction rate technique, where all of the necessary reactants, other than the sample being analyzed, are either inherent in the analyzing system or specifically added or provided to the system for a reason other than calibration. After introduction, the component of interest is exposed to other reactants or flow paths already present in the system. The instrument detector records one of the following to determine the rate of reaction: the increase in the response of the reaction product, a decrease in the signal of the analyte response, or a decrease in the signal from the inherent reactant. With this data, the initial concentration of the analyte is calculated. This type of system can analyze and calibrate simultaneously, reduce the risk of false positives and exposure to toxic vapors, and improve accuracy. Moreover, having an excess of the reactant already present in the system eliminates the need to add commodities, which further reduces cost, logistic problems, and potential contamination. Also, the calculations involved can be simplified by comparison to those of the reaction rate technique. We conducted tests with hypergols as an initial investigation into the feasiblility of the technique.

  16. NVLAP calibration laboratory program

    SciTech Connect

    Cigler, J.L.

    1993-12-31

    This paper presents an overview of the progress up to April 1993 in the development of the Calibration Laboratories Accreditation Program within the framework of the National Voluntary Laboratory Accreditation Program (NVLAP) at the National Institute of Standards and Technology (NIST).

  17. Simplified Vicarious Radiometric Calibration

    NASA Technical Reports Server (NTRS)

    Stanley, Thomas; Ryan, Robert; Holekamp, Kara; Pagnutti, Mary

    2010-01-01

    A measurement-based radiance estimation approach for vicarious radiometric calibration of spaceborne multispectral remote sensing systems has been developed. This simplified process eliminates the use of radiative transfer codes and reduces the number of atmospheric assumptions required to perform sensor calibrations. Like prior approaches, the simplified method involves the collection of ground truth data coincident with the overpass of the remote sensing system being calibrated, but this approach differs from the prior techniques in both the nature of the data collected and the manner in which the data are processed. In traditional vicarious radiometric calibration, ground truth data are gathered using ground-viewing spectroradiometers and one or more sun photometer( s), among other instruments, located at a ground target area. The measured data from the ground-based instruments are used in radiative transfer models to estimate the top-of-atmosphere (TOA) target radiances at the time of satellite overpass. These TOA radiances are compared with the satellite sensor readings to radiometrically calibrate the sensor. Traditional vicarious radiometric calibration methods require that an atmospheric model be defined such that the ground-based observations of solar transmission and diffuse-to-global ratios are in close agreement with the radiative transfer code estimation of these parameters. This process is labor-intensive and complex, and can be prone to errors. The errors can be compounded because of approximations in the model and inaccurate assumptions about the radiative coupling between the atmosphere and the terrain. The errors can increase the uncertainty of the TOA radiance estimates used to perform the radiometric calibration. In comparison, the simplified approach does not use atmospheric radiative transfer models and involves fewer assumptions concerning the radiative transfer properties of the atmosphere. This new technique uses two neighboring uniform

  18. In-situ calibration: migrating control system IP module calibration from the bench to the storage ring

    SciTech Connect

    Weber, Jonah M.; Chin, Michael

    2002-04-30

    The Control System for the Advanced Light Source (ALS) at Lawrence Berkeley National Lab (LBNL) uses in-house designed IndustryPack(registered trademark) (IP) modules contained in compact PCI (cPCI) crates with 16-bit analog I/O to control instrumentation. To make the IP modules interchangeable, each module is calibrated for gain and offset compensation. We initially developed a method of verifying and calibrating the IP modules in a lab bench test environment using a PC with LabVIEW. The subsequent discovery that the ADCs have significant drift characteristics over periods of days of installed operation prompted development of an ''in-situ'' calibration process--one in which the IP modules can be calibrated without removing them from the cPCI crates in the storage ring. This paper discusses the original LabVIEW PC calibration and the migration to the proposed in-situ EPICS control system calibration.

  19. Mercury CEM Calibration

    SciTech Connect

    John F. Schabron; Joseph F. Rovani; Susan S. Sorini

    2007-03-31

    The Clean Air Mercury Rule (CAMR) which was published in the Federal Register on May 18, 2005, requires that calibration of mercury continuous emissions monitors (CEMs) be performed with NIST-traceable standards. Western Research Institute (WRI) is working closely with the Electric Power Research Institute (EPRI), the National Institute of Standards and Technology (NIST), and the Environmental Protection Agency (EPA) to facilitate the development of the experimental criteria for a NIST traceability protocol for dynamic elemental mercury vapor generators. The traceability protocol will be written by EPA. Traceability will be based on the actual analysis of the output of each calibration unit at several concentration levels ranging from about 2-40 ug/m{sup 3}, and this analysis will be directly traceable to analyses by NIST using isotope dilution inductively coupled plasma/mass spectrometry (ID ICP/MS) through a chain of analyses linking the calibration unit in the power plant to the NIST ID ICP/MS. Prior to this project, NIST did not provide a recommended mercury vapor pressure equation or list mercury vapor pressure in its vapor pressure database. The NIST Physical and Chemical Properties Division in Boulder, Colorado was subcontracted under this project to study the issue in detail and to recommend a mercury vapor pressure equation that the vendors of mercury vapor pressure calibration units can use to calculate the elemental mercury vapor concentration in an equilibrium chamber at a particular temperature. As part of this study, a preliminary evaluation of calibration units from five vendors was made. The work was performed by NIST in Gaithersburg, MD and Joe Rovani from WRI who traveled to NIST as a Visiting Scientist.

  20. Adaptable Multivariate Calibration Models for Spectral Applications

    SciTech Connect

    THOMAS,EDWARD V.

    1999-12-20

    Multivariate calibration techniques have been used in a wide variety of spectroscopic situations. In many of these situations spectral variation can be partitioned into meaningful classes. For example, suppose that multiple spectra are obtained from each of a number of different objects wherein the level of the analyte of interest varies within each object over time. In such situations the total spectral variation observed across all measurements has two distinct general sources of variation: intra-object and inter-object. One might want to develop a global multivariate calibration model that predicts the analyte of interest accurately both within and across objects, including new objects not involved in developing the calibration model. However, this goal might be hard to realize if the inter-object spectral variation is complex and difficult to model. If the intra-object spectral variation is consistent across objects, an effective alternative approach might be to develop a generic intra-object model that can be adapted to each object separately. This paper contains recommendations for experimental protocols and data analysis in such situations. The approach is illustrated with an example involving the noninvasive measurement of glucose using near-infrared reflectance spectroscopy. Extensions to calibration maintenance and calibration transfer are discussed.

  1. DECal: A Spectrophotometric Calibration System for DECam

    NASA Astrophysics Data System (ADS)

    Marshall, J. L.; Rheault, J.-P.; DePoy, D. L.; Prochaska, T.; Allen, R.; Behm, T. W.; Martin, E. C.; Veal, B.; Villanueva, S., Jr.; Williams, P.; Wise, J.

    2016-05-01

    DECal is a new calibration system for the CTIO 4 m Blanco telescope. It is currently being installed as part of the Dark Energy Survey and will provide both broadband flat fields and narrowband (˜1 nm bandwidth) spectrophotometric calibration for the new Dark Energy Camera (DECam). Both of these systems share a new Lambertian flat field screen. The broadband flat field system uses LEDs to illuminate each photometric filter. The spectrophotometric calibration system consists of a monochromator-based tunable light source that is projected onto the flat field screen using a custom line-to-spot fiber bundle and an engineered diffuser. Several calibrated photodiodes positioned along the beam monitor the telescope throughput as a function of wavelength. This system will measure the wavelength-dependent instrumental response function of the total telescope+instrument system in the range 300 <λ< 1100nm. The spectrophotometric calibration will be performed regularly (roughly once per month) to determine the spectral response of the DECam system and to monitor changes in instrumental throughput during the five year Dark Energy Survey project.

  2. Mercury Calibration System

    SciTech Connect

    John Schabron; Eric Kalberer; Joseph Rovani; Mark Sanderson; Ryan Boysen; William Schuster

    2009-03-11

    U.S. Environmental Protection Agency (EPA) Performance Specification 12 in the Clean Air Mercury Rule (CAMR) states that a mercury CEM must be calibrated with National Institute for Standards and Technology (NIST)-traceable standards. In early 2009, a NIST traceable standard for elemental mercury CEM calibration still does not exist. Despite the vacature of CAMR by a Federal appeals court in early 2008, a NIST traceable standard is still needed for whatever regulation is implemented in the future. Thermo Fisher is a major vendor providing complete integrated mercury continuous emissions monitoring (CEM) systems to the industry. WRI is participating with EPA, EPRI, NIST, and Thermo Fisher towards the development of the criteria that will be used in the traceability protocols to be issued by EPA. An initial draft of an elemental mercury calibration traceability protocol was distributed for comment to the participating research groups and vendors on a limited basis in early May 2007. In August 2007, EPA issued an interim traceability protocol for elemental mercury calibrators. Various working drafts of the new interim traceability protocols were distributed in late 2008 and early 2009 to participants in the Mercury Standards Working Committee project. The protocols include sections on qualification and certification. The qualification section describes in general terms tests that must be conducted by the calibrator vendors to demonstrate that their calibration equipment meets the minimum requirements to be established by EPA for use in CAMR monitoring. Variables to be examined include linearity, ambient temperature, back pressure, ambient pressure, line voltage, and effects of shipping. None of the procedures were described in detail in the draft interim documents; however they describe what EPA would like to eventually develop. WRI is providing the data and results to EPA for use in developing revised experimental procedures and realistic acceptance criteria based on

  3. RADIATION SOURCES

    DOEpatents

    Brucer, M.H.

    1958-04-15

    A novel long-lived source of gamma radiation especially suitable for calibration purposes is described. The source of gamma radiation is denoted mock iodine131, which comprises a naixture of barium-133 and cesium-137. The barium and cesium are present in a barium-cesium ratio of approximately 5.7/1 to 14/1, uniformly dispersed in an ion exchange resin and a filter surrounding the resin comprised of a material of atomic number below approximately 51, and substantially 0.7 to 0.9 millimeter thick.

  4. Insitu Calibration of Quartz Crystal Microbalances

    NASA Technical Reports Server (NTRS)

    Albyn, Keith; Burns, Dewit

    2006-01-01

    Computer models that predict the rate at which molecular contamination will deposit on optical surfaces typically use outgassing source terms, measured with quartz crystal microbalances, as a basis for the prediction. The American Society of Testing and Materials, Standard Test Method for Contamination Outgassing Characteristics of Spacecraft Materials (Method E-1559), is probably the best know technique used by the aerospace community to measure the outgassing rates or source terms of materials. A simple method for the insitu calibration of quartz crystal microbalances, based on the heat of enthalphy of Adipic Acid, has been developed and demonstrated by the Marshall Space Flight Center, Environmental Effects Group. The calibration has been demonstrated over a sample temperature range of 25 to 66 degrees Celsius and deposition rates of 7 x 10 (exp -11) grams/cm(sup 2)-s and greater, for several measurement system configurations. This calibration technique is fully compatible with the American Society for Testing and Materials, Method E-1559, as well as other methodology. The calibration requires no modification of outgassing facilities employing an effusion cell and does not degrade the performance or function of typical vacuum systems.

  5. Phase calibration generator

    NASA Technical Reports Server (NTRS)

    Sigman, E. H.

    1988-01-01

    A phase calibration system was developed for the Deep Space Stations to generate reference microwave comb tones which are mixed in with signals received by the antenna. These reference tones are used to remove drifts of the station's receiving system from the detected data. This phase calibration system includes a cable stabilizer which transfers a 20 MHz reference signal from the control room to the antenna cone. The cable stabilizer compensates for delay changes in the long cable which connects its control room subassembly to its antenna cone subassembly in such a way that the 20 MHz is transferred to the cone with no significant degradation of the hydrogen maser atomic clock stability. The 20 MHz reference is used by the comb generator and is also available for use as a reference for receiver LO's in the cone.

  6. Pipeline Calibration for STIS

    NASA Astrophysics Data System (ADS)

    Hodge, P. E.; Hulbert, S. J.; Lindler, D.; Busko, I.; Hsu, J.-C.; Baum, S.; McGrath, M.; Goudfrooij, P.; Shaw, R.; Katsanis, R.; Keener, S.; Bohlin, R.

    The CALSTIS program for calibration of Space Telescope Imaging Spectrograph data in the OPUS pipeline differs in several significant ways from calibration for earlier HST instruments, such as the use of FITS format, computation of error estimates, and association of related exposures. Several steps are now done in the pipeline that previously had to be done off-line by the user, such as cosmic ray rejection and extraction of 1-D spectra. Although the program is linked with IRAF for image and table I/O, it is written in ANSI C rather than SPP, which should make the code more accessible. FITS extension I/O makes use of the new IRAF FITS kernel for images and the HEASARC FITSIO package for tables.

  7. MIRO Calibration Switch Mechanism

    NASA Technical Reports Server (NTRS)

    Suchman, Jason; Salinas, Yuki; Kubo, Holly

    2001-01-01

    The Jet Propulsion Laboratory has designed, analyzed, built, and tested a calibration switch mechanism for the MIRO instrument on the ROSETTA spacecraft. MIRO is the Microwave Instrument for the Rosetta Orbiter; this instrument hopes to investigate the origin of the solar system by studying the origin of comets. Specifically, the instrument will be the first to use submillimeter and millimeter wave heterodyne receivers to remotely examine the P-54 Wirtanen comet. In order to calibrate the instrument, it needs to view a hot and cold target. The purpose of the mechanism is to divert the instrument's field of view from the hot target, to the cold target, and then back into space. This cycle is to be repeated every 30 minutes for the duration of the 1.5 year mission. The paper describes the development of the mechanism, as well as analysis and testing techniques.

  8. Calibration of Germanium Resistance Thermometers

    NASA Technical Reports Server (NTRS)

    Ladner, D.; Urban, E.; Mason, F. C.

    1987-01-01

    Largely completed thermometer-calibration cryostat and probe allows six germanium resistance thermometers to be calibrated at one time at superfluid-helium temperatures. In experiments involving several such thermometers, use of this calibration apparatus results in substantial cost savings. Cryostat maintains temperature less than 2.17 K through controlled evaporation and removal of liquid helium from Dewar. Probe holds thermometers to be calibrated and applies small amount of heat as needed to maintain precise temperature below 2.17 K.

  9. Fast calibration of gas flowmeters

    NASA Technical Reports Server (NTRS)

    Lisle, R. V.; Wilson, T. L.

    1981-01-01

    Digital unit automates calibration sequence using calculator IC and programmable read-only memory to solve calibration equations. Infrared sensors start and stop calibration sequence. Instrument calibrates mass flowmeters or rotameters where flow measurement is based on mass or volume. This automatic control reduces operator time by 80 percent. Solid-state components are very reliable, and digital character allows system accuracy to be determined primarily by accuracy of transducers.

  10. Calibrated Properties Model

    SciTech Connect

    H. H. Liu

    2003-02-14

    This report has documented the methodologies and the data used for developing rock property sets for three infiltration maps. Model calibration is necessary to obtain parameter values appropriate for the scale of the process being modeled. Although some hydrogeologic property data (prior information) are available, these data cannot be directly used to predict flow and transport processes because they were measured on scales smaller than those characterizing property distributions in models used for the prediction. Since model calibrations were done directly on the scales of interest, the upscaling issue was automatically considered. On the other hand, joint use of data and the prior information in inversions can further increase the reliability of the developed parameters compared with those for the prior information. Rock parameter sets were developed for both the mountain and drift scales because of the scale-dependent behavior of fracture permeability. Note that these parameter sets, except those for faults, were determined using the 1-D simulations. Therefore, they cannot be directly used for modeling lateral flow because of perched water in the unsaturated zone (UZ) of Yucca Mountain. Further calibration may be needed for two- and three-dimensional modeling studies. As discussed above in Section 6.4, uncertainties for these calibrated properties are difficult to accurately determine, because of the inaccuracy of simplified methods for this complex problem or the extremely large computational expense of more rigorous methods. One estimate of uncertainty that may be useful to investigators using these properties is the uncertainty used for the prior information. In most cases, the inversions did not change the properties very much with respect to the prior information. The Output DTNs (including the input and output files for all runs) from this study are given in Section 9.4.

  11. Mesoscale hybrid calibration artifact

    DOEpatents

    Tran, Hy D.; Claudet, Andre A.; Oliver, Andrew D.

    2010-09-07

    A mesoscale calibration artifact, also called a hybrid artifact, suitable for hybrid dimensional measurement and the method for make the artifact. The hybrid artifact has structural characteristics that make it suitable for dimensional measurement in both vision-based systems and touch-probe-based systems. The hybrid artifact employs the intersection of bulk-micromachined planes to fabricate edges that are sharp to the nanometer level and intersecting planes with crystal-lattice-defined angles.

  12. Calibration Chamber Testing

    DTIC Science & Technology

    1992-01-30

    penetrometers of different designs, (iii) the effect of rod friction, (iv) the effect of discontinuous operation, and (v) sensing an interface between two sand...layers. Other test results on two designs of 10 cm2 Fugro penetrometers, each with a different position of friction sleeve, assisted in the selection...at different stages in the penetration of a specimen. The calibration tests had the prime purpose of establishing correlations between the penetration

  13. Photometric calibrations for 21st century science

    SciTech Connect

    Kent, Stephen; Kaiser, Mary Elizabeth; Deustua, Susana E.; Smith, J.Allyn; Adelman, Saul; Allam, Sahar S.; Baptista, Brian; Bohlin, Ralph C.; Clem, James L.; Conley, Alex; Edelstein, Jerry; /UC, Berkeley, Space Sci. Dept. /NOAO, Tucson

    2009-02-01

    The answers to fundamental science questions in astrophysics, ranging from the history of the expansion of the universe to the sizes of nearby stars, hinge on our ability to make precise measurements of diverse astronomical objects. As our knowledge of the underlying physics of objects improves along with advances in detectors and instrumentation, the limits on our capability to extract science from measurements is set, not by our lack of understanding of the nature of these objects, but rather by the most mundane of all issues: the precision with which we can calibrate observations in physical units. In principle, photometric calibration is a solved problem - laboratory reference standards such as blackbody furnaces achieve precisions well in excess of those needed for astrophysics. In practice, however, transferring the calibration from these laboratory standards to astronomical objects of interest is far from trivial - the transfer must reach outside the atmosphere, extend over 4{pi} steradians of sky, cover a wide range of wavelengths, and span an enormous dynamic range in intensity. Virtually all spectrophotometric observations today are calibrated against one or more stellar reference sources, such as Vega, which are themselves tied back to laboratory standards in a variety of ways. This system's accuracy is not uniform. Selected regions of the electromagnetic spectrum are calibrated extremely well, but discontinuities of a few percent still exist, e.g., between the optical and infrared. Independently, model stellar atmospheres are used to calibrate the spectra of selected white dwarf stars, e.g. the HST system, but the ultimate accuracy of this system should be verified against laboratory sources. Our traditional standard star systems, while sufficient until now, need to be improved and extended in order to serve future astrophysics experiments. This white paper calls for a program to improve upon and expand the current networks of spectrophotometrically

  14. TIME CALIBRATED OSCILLOSCOPE SWEEP

    DOEpatents

    Owren, H.M.; Johnson, B.M.; Smith, V.L.

    1958-04-22

    The time calibrator of an electric signal displayed on an oscilloscope is described. In contrast to the conventional technique of using time-calibrated divisions on the face of the oscilloscope, this invention provides means for directly superimposing equal time spaced markers upon a signal displayed upon an oscilloscope. More explicitly, the present invention includes generally a generator for developing a linear saw-tooth voltage and a circuit for combining a high-frequency sinusoidal voltage of a suitable amplitude and frequency with the saw-tooth voltage to produce a resultant sweep deflection voltage having a wave shape which is substantially linear with respect to time between equal time spaced incremental plateau regions occurring once each cycle of the sinusoidal voltage. The foregoing sweep voltage when applied to the horizontal deflection plates in combination with a signal to be observed applied to the vertical deflection plates of a cathode ray oscilloscope produces an image on the viewing screen which is essentially a display of the signal to be observed with respect to time. Intensified spots, or certain other conspicuous indications corresponding to the equal time spaced plateau regions of said sweep voltage, appear superimposed upon said displayed signal, which indications are therefore suitable for direct time calibration purposes.

  15. Calibrated Properties Model

    SciTech Connect

    T. Ghezzehej

    2004-10-04

    The purpose of this model report is to document the calibrated properties model that provides calibrated property sets for unsaturated zone (UZ) flow and transport process models (UZ models). The calibration of the property sets is performed through inverse modeling. This work followed, and was planned in, ''Technical Work Plan (TWP) for: Unsaturated Zone Flow Analysis and Model Report Integration'' (BSC 2004 [DIRS 169654], Sections 1.2.6 and 2.1.1.6). Direct inputs to this model report were derived from the following upstream analysis and model reports: ''Analysis of Hydrologic Properties Data'' (BSC 2004 [DIRS 170038]); ''Development of Numerical Grids for UZ Flow and Transport Modeling'' (BSC 2004 [DIRS 169855]); ''Simulation of Net Infiltration for Present-Day and Potential Future Climates'' (BSC 2004 [DIRS 170007]); ''Geologic Framework Model'' (GFM2000) (BSC 2004 [DIRS 170029]). Additionally, this model report incorporates errata of the previous version and closure of the Key Technical Issue agreement TSPAI 3.26 (Section 6.2.2 and Appendix B), and it is revised for improved transparency.

  16. Radiation calibration targets

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Several prominent features of Mars Pathfinder and surrounding terrain are seen in this image, taken by the Imager for Mars Pathfinder on July 4 (Sol 1), the spacecraft's first day on the Red Planet. Portions of a lander petal are at the lower part of the image. At the left, the mechanism for the high-gain antenna can be seen. The dark area along the right side of the image represents a portion of the low-gain antenna. The radiation calibration target is at the right. The calibration target is made up of a number of materials with well-characterized colors. The known colors of the calibration targets allow scientists to determine the true colors of the rocks and soils of Mars. Three bull's-eye rings provide a wide range of brightness for the camera, similar to a photographer's grayscale chart. In the middle of the bull's-eye is a 5-inch tall post that casts a shadow, which is distorted in this image due to its location with respect to the lander camera.

    A large rock is located at the near center of the image. Smaller rocks and areas of soil are strewn across the Martian terrain up to the horizon line.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C.

  17. Comparison of Spectral Radiance Calibration Techniques Used for Backscatter Ultraviolet Satellite Instruments

    NASA Technical Reports Server (NTRS)

    Kowalewski, Matthew G.; Janz, Scott

    2014-01-01

    Methods for determining the absolute radiometric calibration sensitivities of backscatter ultraviolet (BUV) satellite instruments are compared as part of an effort to minimize pre-launch calibration errors. An internally illuminated integrating sphere source has been used for the Shuttle Solar BUV (SSBUV), Total Ozone Mapping Spectrometer (TOMS), Ozone Mapping Instrument (OMI), and Global Ozone Monitoring Experiment 2 (GOME-2) using standardized procedures traceable to national standards. These sphere-based sensitivities agree to within three percent [k equals 2] relative to calibrations performed using an external diffuser illuminated by standard irradiance sources, the customary radiance calibration method for BUV instruments. The uncertainty for these calibration techniques as implemented at the NASA Goddard Space Flight Centers Radiometric Calibration and Development Laboratory is shown to be 4 percent at 250nm [k equals 2] when using a single traceable calibration standard. Significant reduction in the uncertainty of nearly 1 percent is demonstrated when multiple calibration standards are used.

  18. The MIRI Medium Resolution Spectrometer calibration pipeline

    NASA Astrophysics Data System (ADS)

    Labiano, A.; Azzollini, R.; Bailey, J.; Beard, S.; Dicken, D.; García-Marín, M.; Geers, V.; Glasse, A.; Glauser, A.; Gordon, K.; Justtanont, K.; Klaassen, P.; Lahuis, F.; Law, D.; Morrison, J.; Müller, M.; Rieke, G.; Vandenbussche, B.; Wright, G.

    2016-07-01

    The Mid-Infrared Instrument (MIRI) Medium Resolution Spectrometer (MRS) is the only mid-IR Integral Field Spectrometer on board James Webb Space Telescope. The complexity of the MRS requires a very specialized pipeline, with some specific steps not present in other pipelines of JWST instruments, such as fringe corrections and wavelength offsets, with different algorithms for point source or extended source data. The MRS pipeline has also two different variants: the baseline pipeline, optimized for most foreseen science cases, and the optimal pipeline, where extra steps will be needed for specific science cases. This paper provides a comprehensive description of the MRS Calibration Pipeline from uncalibrated slope images to final scientific products, with brief descriptions of its algorithms, input and output data, and the accessory data and calibration data products necessary to run the pipeline.

  19. Internet-Based Calibration of a Multifunction Calibrator

    SciTech Connect

    BUNTING BACA,LISA A.; DUDA JR.,LEONARD E.; WALKER,RUSSELL M.; OLDHAM,NILE; PARKER,MARK

    2000-12-19

    A new way of providing calibration services is evolving which employs the Internet to expand present capabilities and make the calibration process more interactive. Sandia National Laboratories and the National Institute of Standards and Technology are collaborating to set up and demonstrate a remote calibration of multijunction calibrators using this Internet-based technique that is becoming known as e-calibration. This paper describes the measurement philosophy and the Internet resources that can provide real-time audio/video/data exchange, consultation and training, as well as web-accessible test procedures, software and calibration reports. The communication system utilizes commercial hardware and software that should be easy to integrate into most calibration laboratories.

  20. Internet-based calibration of a multifunction calibrator

    SciTech Connect

    BUNTING BACA,LISA A.; DUDA JR.,LEONARD E.; WALKER,RUSSELL M.; OLDHAM,NILE; PARKER,MARK

    2000-04-17

    A new way of providing calibration services is evolving which employs the Internet to expand present capabilities and make the calibration process more interactive. Sandia National Laboratories and the National Institute of Standards and Technology are collaborating to set up and demonstrate a remote calibration of multifunction calibrators using this Internet-based technique that is becoming known as e-calibration. This paper describes the measurement philosophy and the Internet resources that can provide real-time audio/video/data exchange, consultation and training, as well as web-accessible test procedures, software and calibration reports. The communication system utilizes commercial hardware and software that should be easy to integrate into most calibration laboratories.

  1. Calibration of a helium-cooled infrared spatial radiometer and grating spectrometer

    NASA Technical Reports Server (NTRS)

    Jacobsen, Larry; Sargent, Steve; Wyatt, Clair L.; Steed, Allan J.

    1992-01-01

    Methods used by the Space Dynamics Laboratory of Utah State University (SDL/USU) to calibrate infrared sensors are described, using the Infrared Background Signature Survey (IBSS) spatial radiometer and grating spectrometer as examples. A calibration equation and a radiometric model are given for each sensor to describe their responsivity in terms of individual radiometric parameters. The calibration equation terms include dark offset, linearity, absolute responsivity, and measurement uncertainty, and the radiometric model domains include spatial, spectral, and temporal domains. A portable calibration facility, designed and fabricated by SDL/USU, provided collimated, extended, diffuse scatter, and Jones sources in a single cryogenic dewar. This multi-function calibrator allowed calibration personnel to complete a full calibration of the IBSS infrared radiometer and spectrometer in two 15-day periods. A calibration data system was developed to control and monitor the calibration facility, and to record and analyze sensor data.

  2. Third COS FUV Lifetime Calibration Program: Flatfield and Flux Calibrations

    NASA Astrophysics Data System (ADS)

    Debes, J. H.; Becker, G.; Roman-Duval, J.; Ely, J.; Massa, D.; Oliveira, C.; Plesha, R.; Proffitt, C.; Taylor, J.

    2016-10-01

    As part of the calibration of the third lifetime position (LP3) of the Cosmic Origins Spectrograph (COS) Far-Ultraviolet (FUV) detector, observations of WD 0308-565 were obtained with the G130M, G160M, and G140L gratings and observations of GD 71 were obtained in the G160M grating through the Point Source Aperture (PSA) to derive low-order flatfields (L-flats) and sensitivities at LP3. Observations were executed for all CENWAVES and all FP-POS with the exception of G130M/1055 and G130M/1096, which remained at LP2. The derivation of the L-flats and sensitivities at LP3 differed from their LP1 and LP2 counterparts in a few key ways, which we describe in this report. Firstly, we quantified a cut-off in spatial frequency that we assigned to the L-flats. Secondly, we derived a new method for simultaneously fitting both the L-flats, pixel-to-pixel flats (P-flats), and sensitvities which we compared to our previous method of separately fitting L-flats and sensitivities. These new methods produce comparable results, but provide us with an external test on the robustness of each approach individually. The results of our work show that with the new profile extraction routines, sensitivities, and L-flats, the relative and absolute flux calibration accuracies (1% and 2% respectively) at LP3 are slightly improved relative to previous locations on the COS FUV detector.

  3. Comparison of Two Methodologies for Calibrating Satellite Instruments in the Visible and Near Infrared

    NASA Technical Reports Server (NTRS)

    Barnes, Robert A.; Brown, Steven W.; Lykke, Keith R.; Guenther, Bruce; Xiong, Xiaoxiong (Jack); Butler, James J.

    2010-01-01

    Traditionally, satellite instruments that measure Earth-reflected solar radiation in the visible and near infrared wavelength regions have been calibrated for radiance response in a two-step method. In the first step, the spectral response of the instrument is determined using a nearly monochromatic light source, such a lamp-illuminated monochromator. Such sources only provide a relative spectral response (RSR) for the instrument, since they do not act as calibrated sources of light nor do they typically fill the field-of-view of the instrument. In the second step, the instrument views a calibrated source of broadband light, such as lamp-illuminated integrating sphere. In the traditional method, the RSR and the sphere spectral radiance are combined and, with the instrument's response, determine the absolute spectral radiance responsivity of the instrument. More recently, an absolute calibration system using widely tunable monochromatic laser systems has been developed, Using these sources, the absolute spectral responsivity (ASR) of an instrument can be determined on a wavelength-hy-wavelength basis. From these monochromatic ASRs. the responses of the instrument bands to broadband radiance sources can be calculated directly, eliminating the need for calibrated broadband light sources such as integrating spheres. Here we describe the laser-based calibration and the traditional broad-band source-based calibration of the NPP VIIRS sensor, and compare the derived calibration coefficients for the instrument. Finally, we evaluate the impact of the new calibration approach on the on-orbit performance of the sensor.

  4. New radiation protection calibration facility at CERN.

    PubMed

    Brugger, Markus; Carbonez, Pierre; Pozzi, Fabio; Silari, Marco; Vincke, Helmut

    2014-10-01

    The CERN radiation protection group has designed a new state-of-the-art calibration laboratory to replace the present facility, which is >20 y old. The new laboratory, presently under construction, will be equipped with neutron and gamma sources, as well as an X-ray generator and a beta irradiator. The present work describes the project to design the facility, including the facility placement criteria, the 'point-zero' measurements and the shielding study performed via FLUKA Monte Carlo simulations.

  5. Improved Calibration Of Acoustic Plethysmographic Sensors

    NASA Technical Reports Server (NTRS)

    Zuckerwar, Allan J.; Davis, David C.

    1993-01-01

    Improved method of calibration of acoustic plethysmographic sensors involves acoustic-impedance test conditions like those encountered in use. Clamped aluminum tube holds source of sound (hydrophone) inside balloon. Test and reference sensors attached to outside of balloon. Sensors used to measure blood flow, blood pressure, heart rate, breathing sounds, and other vital signs from surfaces of human bodies. Attached to torsos or limbs by straps or adhesives.

  6. Invited Article: Deep Impact instrument calibration.

    PubMed

    Klaasen, Kenneth P; A'Hearn, Michael F; Baca, Michael; Delamere, Alan; Desnoyer, Mark; Farnham, Tony; Groussin, Olivier; Hampton, Donald; Ipatov, Sergei; Li, Jianyang; Lisse, Carey; Mastrodemos, Nickolaos; McLaughlin, Stephanie; Sunshine, Jessica; Thomas, Peter; Wellnitz, Dennis

    2008-09-01

    Calibration of NASA's Deep Impact spacecraft instruments allows reliable scientific interpretation of the images and spectra returned from comet Tempel 1. Calibrations of the four onboard remote sensing imaging instruments have been performed in the areas of geometric calibration, spatial resolution, spectral resolution, and radiometric response. Error sources such as noise (random, coherent, encoding, data compression), detector readout artifacts, scattered light, and radiation interactions have been quantified. The point spread functions (PSFs) of the medium resolution instrument and its twin impactor targeting sensor are near the theoretical minimum [ approximately 1.7 pixels full width at half maximum (FWHM)]. However, the high resolution instrument camera was found to be out of focus with a PSF FWHM of approximately 9 pixels. The charge coupled device (CCD) read noise is approximately 1 DN. Electrical cross-talk between the CCD detector quadrants is correctable to <2 DN. The IR spectrometer response nonlinearity is correctable to approximately 1%. Spectrometer read noise is approximately 2 DN. The variation in zero-exposure signal level with time and spectrometer temperature is not fully characterized; currently corrections are good to approximately 10 DN at best. Wavelength mapping onto the detector is known within 1 pixel; spectral lines have a FWHM of approximately 2 pixels. About 1% of the IR detector pixels behave badly and remain uncalibrated. The spectrometer exhibits a faint ghost image from reflection off a beamsplitter. Instrument absolute radiometric calibration accuracies were determined generally to <10% using star imaging. Flat-field calibration reduces pixel-to-pixel response differences to approximately 0.5% for the cameras and <2% for the spectrometer. A standard calibration image processing pipeline is used to produce archival image files for analysis by researchers.

  7. Calibration of seismic wave propagation in Jordan

    SciTech Connect

    Al-Husien, A; Amrat, A; Harris, D; Mayeda, K; Nakanishi, K; Rodgers, A; Ruppert, S; Ryall, F; Skinnell, K; Yazjeen, T

    1999-07-23

    The Natural Resources Authority of Jordan (NRA), the USGS and LLNL have a collaborative project to improve the calibration of seismic propagation in Jordan and surrounding regions. This project serves common goals of CTBT calibration and earthquake hazard assessment in the region. These objectives include accurate location of local and regional earthquakes, calibration of magnitude scales, and the development of local and regional propagation models. In the CTBT context, better propagation models and more accurately located events in the Dead Sea rift region can serve as (potentially GT5) calibration events for generating IMS location corrections. The detection and collection of mining explosions underpins discrimination research. The principal activity of this project is the deployment of two broadband stations at Hittiyah (south Jordan) and Ruweishid (east Jordan). These stations provide additional paths in the region to constrain structure with surface wave and body wave tomography. The Ruweishid station is favorably placed to provide constraints on Arabian platform structure. Waveform modeling with long-period observations of larger earthquakes will provide constraints on 1-D velocity models of the crust and upper mantle. Data from these stations combined with phase observations from the 26 short-period stations of the Jordan National Seismic Network (JNSN) may allow the construction of a more detailed velocity model of Jordan. The Hittiyah station is an excellent source of ground truth information for the six phosphate mines of southern Jordan and Israel. Observations of mining explosions collected by this station have numerous uses: for definition of templates for screening mining explosions, as ground truth events for calibrating travel-time models, and as explosion populations in development and testing discriminants. Following previously established procedures for identifying explosions, we have identified more than 200 explosions from the first 85 days of

  8. Primary calibration in acoustics metrology

    NASA Astrophysics Data System (ADS)

    Bacelar Milhomem, T. A.; Defilippo Soares, Z. M.

    2015-01-01

    SI unit in acoustics is realized by the reciprocity calibrations of laboratory standard microphones in pressure field, free field and diffuse field. Calibrations in pressure field and in free field are already consolidated and the Inmetro already done them. Calibration in diffuse field is not yet consolidated, however, some national metrology institutes, including Inmetro, are conducting researches on this subject. This paper presents the reciprocity calibration, the results of Inmetro in recent key comparisons and the research that is being developed for the implementation of reciprocity calibration in diffuse field.

  9. Calibration of triaxial fluxgate gradiometer

    SciTech Connect

    Vcelak, Jan

    2006-04-15

    The description of simple and fast calibration procedures used for double-probe triaxial fluxgate gradiometer is provided in this paper. The calibration procedure consists of three basic steps. In the first step both probes are calibrated independently in order to reach constant total field reading in every position. Both probes are numerically aligned in the second step in order that the gradient reading is zero in homogenous magnetic field. The third step consists of periodic drift calibration during measurement. The results and detailed description of each calibration step are presented and discussed in the paper. The gradiometer is finally verified during the detection of the metal object in the measuring grid.

  10. LBCS: The LOFAR Long-Baseline Calibrator Survey

    NASA Astrophysics Data System (ADS)

    Jackson, N.; Tagore, A.; Deller, A.; Moldón, J.; Varenius, E.; Morabito, L.; Wucknitz, O.; Carozzi, T.; Conway, J.; Drabent, A.; Kapinska, A.; Orrù, E.; Brentjens, M.; Blaauw, R.; Kuper, G.; Sluman, J.; Schaap, J.; Vermaas, N.; Iacobelli, M.; Cerrigone, L.; Shulevski, A.; ter Veen, S.; Fallows, R.; Pizzo, R.; Sipior, M.; Anderson, J.; Avruch, I. M.; Bell, M. E.; van Bemmel, I.; Bentum, M. J.; Best, P.; Bonafede, A.; Breitling, F.; Broderick, J. W.; Brouw, W. N.; Brüggen, M.; Ciardi, B.; Corstanje, A.; de Gasperin, F.; de Geus, E.; Eislöffel, J.; Engels, D.; Falcke, H.; Garrett, M. A.; Grießmeier, J. M.; Gunst, A. W.; van Haarlem, M. P.; Heald, G.; Hoeft, M.; Hörandel, J.; Horneffer, A.; Intema, H.; Juette, E.; Kuniyoshi, M.; van Leeuwen, J.; Loose, G. M.; Maat, P.; McFadden, R.; McKay-Bukowski, D.; McKean, J. P.; Mulcahy, D. D.; Munk, H.; Pandey-Pommier, M.; Polatidis, A. G.; Reich, W.; Röttgering, H. J. A.; Rowlinson, A.; Scaife, A. M. M.; Schwarz, D. J.; Steinmetz, M.; Swinbank, J.; Thoudam, S.; Toribio, M. C.; Vermeulen, R.; Vocks, C.; van Weeren, R. J.; Wise, M. W.; Yatawatta, S.; Zarka, P.

    2016-11-01

    We outline the LOFAR Long-Baseline Calibrator Survey (LBCS), whose aim is to identify sources suitable for calibrating the highest-resolution observations made with the International LOFAR Telescope, which include baselines >1000 km. Suitable sources must contain significant correlated flux density (≳ 50 - 100 mJy) at frequencies around 110-190 MHz on scales of a few hundred milliarcseconds. At least for the 200-300-km international baselines, we find around 1 suitable calibrator source per square degree over a large part of the northern sky, in agreement with previous work. This should allow a randomly selected target to be successfully phase calibrated on the international baselines in over 50% of cases. Products of the survey include calibrator source lists and fringe-rate and delay maps of wide areas - typically a few degrees - around each source. The density of sources with significant correlated flux declines noticeably with baseline length over the range 200-600 km, with good calibrators on the longest baselines appearing only at the rate of 0.5 per sq. deg. Coherence times decrease from 1-3 min on 200-km baselines to about 1 min on 600-km baselines, suggesting that ionospheric phase variations contain components with scales of a few hundred kilometres. The longest median coherence time, at just over 3 min, is seen on the DE609 baseline, which at 227 km is close to being the shortest. We see median coherence times of between 80 and 110 s on the four longest baselines (580-600 km), and about 2 min for the other baselines. The success of phase transfer from calibrator to target is shown to be influenced by distance, in a manner that suggests a coherence patch at 150-MHz of the order of 1 deg. Although source structures cannot be measured in these observations, we deduce that phase transfer is affected if the calibrator source structure is not known. We give suggestions for calibration strategies and choice of calibrator sources, and describe the access to

  11. Mercury CEM Calibration

    SciTech Connect

    John Schabron; Joseph Rovani; Mark Sanderson

    2008-02-29

    Mercury continuous emissions monitoring systems (CEMS) are being implemented in over 800 coal-fired power plant stacks. The power industry desires to conduct at least a full year of monitoring before the formal monitoring and reporting requirement begins on January 1, 2009. It is important for the industry to have available reliable, turnkey equipment from CEM vendors. Western Research Institute (WRI) is working closely with the Electric Power Research Institute (EPRI), the National Institute of Standards and Technology (NIST), and the Environmental Protection Agency (EPA) to facilitate the development of the experimental criteria for a NIST traceability protocol for dynamic elemental mercury vapor generators. The generators are used to calibrate mercury CEMs at power plant sites. The Clean Air Mercury Rule (CAMR) which was published in the Federal Register on May 18, 2005 requires that calibration be performed with NIST-traceable standards (Federal Register 2007). Traceability procedures will be defined by EPA. An initial draft traceability protocol was issued by EPA in May 2007 for comment. In August 2007, EPA issued an interim traceability protocol for elemental mercury generators (EPA 2007). The protocol is based on the actual analysis of the output of each calibration unit at several concentration levels ranging initially from about 2-40 {micro}g/m{sup 3} elemental mercury, and in the future down to 0.2 {micro}g/m{sup 3}, and this analysis will be directly traceable to analyses by NIST. The document is divided into two separate sections. The first deals with the qualification of generators by the vendors for use in mercury CEM calibration. The second describes the procedure that the vendors must use to certify the generator models that meet the qualification specifications. The NIST traceable certification is performance based, traceable to analysis using isotope dilution inductively coupled plasma/mass spectrometry performed by NIST in Gaithersburg, MD. The

  12. Automatic force balance calibration system

    NASA Technical Reports Server (NTRS)

    Ferris, Alice T. (Inventor)

    1996-01-01

    A system for automatically calibrating force balances is provided. The invention uses a reference balance aligned with the balance being calibrated to provide superior accuracy while minimizing the time required to complete the calibration. The reference balance and the test balance are rigidly attached together with closely aligned moment centers. Loads placed on the system equally effect each balance, and the differences in the readings of the two balances can be used to generate the calibration matrix for the test balance. Since the accuracy of the test calibration is determined by the accuracy of the reference balance and current technology allows for reference balances to be calibrated to within .+-.0.05%, the entire system has an accuracy of a .+-.0.2%. The entire apparatus is relatively small and can be mounted on a movable base for easy transport between test locations. The system can also accept a wide variety of reference balances, thus allowing calibration under diverse load and size requirements.

  13. Calibration of the Geostationary Imaging Fourier Transform Spectrometer (GIFTS)

    NASA Technical Reports Server (NTRS)

    Best, F. A.; Revercomb, H. E.; Bingham, G. E.; Knuteson, R. O.; Tobin, D. C.; LaPorte, D. D.; Smith, W. L.

    2001-01-01

    The NASA New Millennium Program's Geostationary Imaging Fourier Transform Spectrometer (GIFTS) requires highly accurate radiometric and spectral calibration in order to carry out its mission to provide water vapor, wind, temperature, and trace gas profiling from geostationary orbit. A calibration concept has been developed for the GIFTS Phase A instrument design. The in-flight calibration is performed using views of two on-board blackbody sources along with cold space. A radiometric calibration uncertainty analysis has been developed and used to show that the expected performance for GIFTS exceeds its top level requirement to measure brightness temperature to better than 1 K. For the Phase A GIFTS design, the spectral calibration is established by the highly stable diode laser used as the reference for interferogram sampling, and verified with comparisons to atmospheric calculations.

  14. Uncertainty and Dimensional Calibrations

    PubMed Central

    Doiron, Ted; Stoup, John

    1997-01-01

    The calculation of uncertainty for a measurement is an effort to set reasonable bounds for the measurement result according to standardized rules. Since every measurement produces only an estimate of the answer, the primary requisite of an uncertainty statement is to inform the reader of how sure the writer is that the answer is in a certain range. This report explains how we have implemented these rules for dimensional calibrations of nine different types of gages: gage blocks, gage wires, ring gages, gage balls, roundness standards, optical flats indexing tables, angle blocks, and sieves. PMID:27805114

  15. Transient Calorimeter Calibration System

    DTIC Science & Technology

    1975-03-01

    can withstand the high heat flux levels encountered during calibration. 3 d. The verification of absorptivity of a colloidal graphite coat- ing used...CC4-)Ŕ ýz- ix w- Vj m ~ CL 4) > r- 4-) r-)W *. M 0 0 a 4) u.) . CJ C4) Lfl 𔃺 4%. C6 0) 0 ~ 4 -0 E 36 The colloidal graphite remains the most...before and after exposure. Such tests performed with the colloidal graphite coating yielded no apparent change in absorptivity up through 5 kW/cm2 . In

  16. White Dwarf Calibration

    NASA Astrophysics Data System (ADS)

    Colina, Luis

    1994-01-01

    As a result of last November calibration workshop, all parties agreed that the HST should be switched to the WD basis for absolute fluxes. This proposal implements that decision. A measurement of the absolute sensitivity of the FOS detectors will be performed using theoretical pure hydrogen model atmosphere calculations for three white dwarfs. The high resolution gratings will be used in the 1 arcsec aperture. A four stage peakup of the standard star provides centering in the aperture. Observations are requested for fall 94 with repeated observations about two months after.

  17. Uncertainty and Dimensional Calibrations.

    PubMed

    Doiron, Ted; Stoup, John

    1997-01-01

    The calculation of uncertainty for a measurement is an effort to set reasonable bounds for the measurement result according to standardized rules. Since every measurement produces only an estimate of the answer, the primary requisite of an uncertainty statement is to inform the reader of how sure the writer is that the answer is in a certain range. This report explains how we have implemented these rules for dimensional calibrations of nine different types of gages: gage blocks, gage wires, ring gages, gage balls, roundness standards, optical flats indexing tables, angle blocks, and sieves.

  18. SAR antenna calibration techniques

    NASA Technical Reports Server (NTRS)

    Carver, K. R.; Newell, A. C.

    1978-01-01

    Calibration of SAR antennas requires a measurement of gain, elevation and azimuth pattern shape, boresight error, cross-polarization levels, and phase vs. angle and frequency. For spaceborne SAR antennas of SEASAT size operating at C-band or higher, some of these measurements can become extremely difficult using conventional far-field antenna test ranges. Near-field scanning techniques offer an alternative approach and for C-band or X-band SARs, give much improved accuracy and precision as compared to that obtainable with a far-field approach.

  19. Dynamic Torque Calibration Unit

    NASA Technical Reports Server (NTRS)

    Agronin, Michael L.; Marchetto, Carl A.

    1989-01-01

    Proposed dynamic torque calibration unit (DTCU) measures torque in rotary actuator components such as motors, bearings, gear trains, and flex couplings. Unique because designed specifically for testing components under low rates. Measures torque in device under test during controlled steady rotation or oscillation. Rotor oriented vertically, supported by upper angular-contact bearing and lower radial-contact bearing that floats axially to prevent thermal expansion from loading bearings. High-load capacity air bearing available to replace ball bearings when higher load capacity or reduction in rate noise required.

  20. DOE radiological calibrations intercomparison program: Results of fiscal year 1988

    SciTech Connect

    Cummings, F.M.; McDonald, J.C.; Murphy, M.K.

    1989-08-01

    Calibration measurements for personnel dosimetry purposes must be both accurate and consistent with national standards. In order to satisfy these requirements, the following methods are usually employed. In one case, a radiation source is sent to the National Institute of Standards and Technology (NIST), formerly the National Bureau of Standards, for calibration and is returned to the laboratory to be used as a local standard. Another method involves the calibration of an instrument, such as an ionization chamber, by NIST. After calibration, this instrument is then used to measure the exposure rate delivered by radiation sources at the laboratory. Such calibrations by NIST are essential, but they do not provide a complete check on the quality of the calibrations that are carried out by the individual laboratory. Additional measurements are necessary to assure the quality of such measurements. When laboratory staff are asked to carry our measurements with calibrated instruments and report results for evaluation, they are participating in a measurement quality assurance (MQA) program. Such a program tests not only the quality of the equipment but also the ability of the staff to correctly use and interpret the results obtained with the equipment. The NIST operates an MQA program with a selected number of calibration laboratories. Pacific Northwest Laboratory (PNL) participates in this MQA program even though NIST test only x-ray and gamma-ray measurements. The US Department of Energy (DOE) intercomparison program was designed specifically to include x-ray, gamma-ray, beta, and neutron calibrations for personnel dosimetry purposes. This program serves a need that is not being met by NIST, and it provides documentation of the accuracy and uniformity of the radiological calibrations carried out in DOE facilities. 7 refs., 3 figs., 6 tabs.

  1. Design of the ERIS calibration unit

    NASA Astrophysics Data System (ADS)

    Dolci, Mauro; Valentini, Angelo; Di Rico, Gianluca; Esposito, Simone; Ferruzzi, Debora; Riccardi, Armando; Spanò, Paolo; Antichi, Jacopo

    2016-08-01

    The Enhanced Resolution Imager and Spectrograph (ERIS) is a new-generation instrument for the Cassegrain focus of the ESO UT4/VLT, aimed at performing AO-assisted imaging and medium resolution spectroscopy in the 1-5 micron wavelength range. ERIS consists of the 1-5 micron imaging camera NIX, the 1-2.5 micron integral field spectrograph SPIFFIER (a modified version of SPIFFI, currently operating on SINFONI), the AO module and the internal Calibration Unit (ERIS CU). The purpose of this unit is to provide facilities to calibrate the scientific instruments in the 1-2.5 micron and to perform troubleshooting and periodic maintenance tests of the AO module (e.g. NGS and LGS WFS internal calibrations and functionalities, ERIS differential flexures) in the 0.5 - 1 μm range. The ERIS CU must therefore be designed in order to provide, over the full 0.5 - 2.5 μm range, the following capabilities: 1) illumination of both the telescope focal plane and the telescope pupil with a high-degree of uniformity; 2) artificial point-like and extended sources onto the telescope focal plane, with high accuracy in both positioning and FWHM; 3) wavelength calibration; 4) high stability of these characteristics. In this paper the design of the ERIS CU, and the solutions adopted to fulfill all these requirements, is described. The ERIS CU construction is foreseen to start at the end of 2016.

  2. Beam Calibration of Radio Telescopes with Drones

    NASA Astrophysics Data System (ADS)

    Chang, Chihway; Monstein, Christian; Refregier, Alexandre; Amara, Adam; Glauser, Adrian; Casura, Sarah

    2015-11-01

    We present a multi-frequency far-field beam map for the 5m dish telescope at the Bleien Observatory measured using a commercially available drone. We describe the hexacopter drone used in this experiment, the design of the flight pattern, and the data analysis scheme. This is the first application of this calibration method to a single dish radio telescope in the far-field. The high signal-to-noise data allows us to characterise the beam pattern with high accuracy out to at least the 4th side-lobe. The resulting 2D beam pattern is compared with that derived from a more traditional calibration approach using an astronomical calibration source. We discuss the advantages of this method compared to other beam calibration methods. Our results show that this drone-based technique is very promising for ongoing and future radio experiments, where the knowledge of the beam pattern is key to obtaining high-accuracy cosmological and astronomical measurements.

  3. NIST Calibration of a Neutron Spectrometer ROSPEC.

    PubMed

    Heimbach, Craig

    2006-01-01

    A neutron spectrometer was acquired for use in the measurement of National Institute of Standards and Technology neutron fields. The spectrometer included options for the measurement of low and high energy neutrons, for a total measurement range from 0.01 eV up to 17 MeV. The spectrometer was evaluated in calibration fields and was used to determine the neutron spectrum of an Americium-Beryllium neutron source. The calibration fields used included bare and moderated (252)Cf, monoenergetic neutron fields of 2.5 MeV and 14 MeV, and a thermal-neutron beam. Using the calibration values determined in this exercise, the spectrometer gives a good approximation of the neutron spectrum, and excellent values for neutron fluence, for all NIST calibration fields. The spectrometer also measured an Americium-Beryllium neutron field in a NIST exposure facility and determined the field quite well. The spectrometer measured scattering effects in neutron spectra which previously could be determined only by calculation or integral measurements.

  4. NIST Calibration of a Neutron Spectrometer ROSPEC

    PubMed Central

    Heimbach, Craig

    2006-01-01

    A neutron spectrometer was acquired for use in the measurement of National Institute of Standards and Technology neutron fields. The spectrometer included options for the measurement of low and high energy neutrons, for a total measurement range from 0.01 eV up to 17 MeV. The spectrometer was evaluated in calibration fields and was used to determine the neutron spectrum of an Americium-Beryllium neutron source. The calibration fields used included bare and moderated 252Cf, monoenergetic neutron fields of 2.5 MeV and 14 MeV, and a thermal-neutron beam. Using the calibration values determined in this exercise, the spectrometer gives a good approximation of the neutron spectrum, and excellent values for neutron fluence, for all NIST calibration fields. The spectrometer also measured an Americium-Beryllium neutron field in a NIST exposure facility and determined the field quite well. The spectrometer measured scattering effects in neutron spectra which previously could be determined only by calculation or integral measurements. PMID:27274944

  5. A Simple Accelerometer Calibrator

    NASA Astrophysics Data System (ADS)

    Salam, R. A.; Islamy, M. R. F.; Munir, M. M.; Latief, H.; Irsyam, M.; Khairurrijal

    2016-08-01

    High possibility of earthquake could lead to the high number of victims caused by it. It also can cause other hazards such as tsunami, landslide, etc. In that case it requires a system that can examine the earthquake occurrence. Some possible system to detect earthquake is by creating a vibration sensor system using accelerometer. However, the output of the system is usually put in the form of acceleration data. Therefore, a calibrator system for accelerometer to sense the vibration is needed. In this study, a simple accelerometer calibrator has been developed using 12 V DC motor, optocoupler, Liquid Crystal Display (LCD) and AVR 328 microcontroller as controller system. The system uses the Pulse Wave Modulation (PWM) form microcontroller to control the motor rotational speed as response to vibration frequency. The frequency of vibration was read by optocoupler and then those data was used as feedback to the system. The results show that the systems could control the rotational speed and the vibration frequencies in accordance with the defined PWM.

  6. Traceable dynamic calibration of force transducers by primary means

    NASA Astrophysics Data System (ADS)

    Vlajic, Nicholas; Chijioke, Ako

    2016-08-01

    We describe an apparatus for traceable, dynamic calibration of force transducers using harmonic excitation, and report calibration measurements of force transducers using this apparatus. In this system, the force applied to the transducer is produced by the acceleration of an attached mass, and is determined according to Newton’s second law, F  =  ma. The acceleration is measured by primary means, using laser interferometry. The capabilities of this system are demonstrated by performing dynamic calibrations of two shear-web-type force transducers up to a frequency of 2 kHz, with an expanded uncertainty below 1.2%. We give an account of all significant sources of uncertainty, including a detailed consideration of the effects of dynamic tilting (rocking), which is a leading source of uncertainty in such harmonic force calibration systems.

  7. MODIS airborne simulator visible and near-infrared calibration, 1991 FIRE-Cirrus field experiment. Calibration version: FIRE King 1.1

    NASA Technical Reports Server (NTRS)

    Arnold, G. Thomas; Fitzgerald, Michael; Grant, Patrick S.; King, Michael D.

    1994-01-01

    Calibration of the visible and near-infrared channels of the MODIS Airborne Simulator (MAS) is derived from observations of a calibrated light source. For the 1991 FIRE-Cirrus field experiment, the calibrated light source was the NASA Goddard 48-inch integrating hemisphere. Laboratory tests during the FIRE Cirrus field experiment were conducted to calibrate the hemisphere and from the hemisphere to the MAS. The purpose of this report is to summarize the FIRE-Cirrus hemisphere calibration, and then describe how the MAS was calibrated from observations of the hemisphere data. All MAS calibration measurements are presented, and determination of the MAS calibration coefficients (raw counts to radiance conversion) is discussed. Thermal sensitivity of the MAS visible and near-infrared calibration is also discussed. Typically, the MAS in-flight is 30 to 60 degrees C colder than the room temperature laboratory calibration. Results from in-flight temperature measurements and tests of the MAS in a cold chamber are given, and from these, equations are derived to adjust the MAS in-flight data to what the value would be at laboratory conditions. For FIRE-Cirrus data, only channels 3 through 6 were found to be temperature sensitive. The final section of this report describes comparisons to an independent MAS (room temperature) calibration by Ames personnel using their 30-inch integrating sphere.

  8. Quadrature phase interferometer used to calibrate dial indicator calibrators

    NASA Astrophysics Data System (ADS)

    Huang, Shau-Chi; Liou, Huay-Chung; Peng, Gwo-Sheng; Lu, Ming-Feng

    2001-10-01

    To calibrate dial indicators, gage blocks or dial indicator calibrators are usually used. For better accuracy and resolution, interferometers are used to calibrate dial indicator calibrators. Systematic errors of laser interferometers can be classified into three categories of intrinsic errors, environment errors and installation errors. Intrinsic errors include laser wavelength error, electronic error and optics nonlinearity. In order to achieve nanometer accuracy, minimizing intrinsic error is crucial. In this paper, we will address the problems of minimizing the optics nonlinearity error and describe the discrete-time signal processing method to minimize the electronic error, nonlinearity error and drift by simply using quadrature phase interferometer for nanometer accuracy and linearity.

  9. CALIBRATION OF PHOTOELASTIC MODULATORS IN THE VACUUM UV.

    SciTech Connect

    OAKBERG, T.C.; TRUNK, J.; SUTHERLAND, J.C.

    2000-02-15

    Measurements of circular dichroism (CD) in the UV and vacuum UV have used photoelastic modulators (PEMs) for high sensitivity (to about 10{sup -6}). While a simple technique for wavelength calibration of the PEMs has been used with good results, several features of these calibration curves have not been understood. The authors have calibrated a calcium fluoride PEM and a lithium fluoride PEM using the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory as a light source. These experiments showed calibration graphs that are linear bit do not pass through the graph origin. A second ''multiple pass'' experiment with laser light of a single wavelength, performed on the calcium fluoride PEM, demonstrates the linearity of the PEM electronics. This implies that the calibration behavior results from intrinsic physical properties of the PEM optical element material. An algorithm for generating calibration curves for calcium fluoride and lithium fluoride PEMs has been developed. The calibration curves for circular dichroism measurement for the two PEMs investigated in this study are given as examples.

  10. Uniform calibration of night vision goggles and test sets

    NASA Astrophysics Data System (ADS)

    Eppeldauer, George P.

    2007-10-01

    There are orders of magnitude differences between the ~0.1 % (k=2) uncertainty of NIST reference detector calibrations and the uncertainty of night vision (NV) goggle measurements. NIST developed a night vision radiometer calibration facility including NV radiometer transfer standards. The transfer standards, that propagate the radiance responsivity scale to the military primary standards laboratories, are calibrated against a NIST reference radiometer. The reference radiometer has been calibrated on the NIST Spectral Comparator Facility (SCF) for spectral power and irradiance responsivities. Spectral considerations are discussed to lower the uncertainties of the radiance responsivity scale transfer to the test sets and then to the goggles. Since direct determination of the final uncertainties in goggle calibrations and measurements is difficult, models have been made to estimate the most important uncertainty components based on individual spectral measurements of the applied source distributions and radiometer spectral responsivities. It is also shown, that because of source spectral mismatch problems, the goggle measurement uncertainty at applications can be much higher than at calibration. A suggestion is being made to mimic the no-moon (stars only) night sky radiation distribution using several LEDs in the test-sets to decrease the large spectral mismatch errors. A broad-band correction factor has been developed to further decrease calibration uncertainty when the goggles to be used have different spectral responsivities than the standard. Geometrical considerations to optimize the radiance measurement angle and the out-of-target blocking are also discussed to decrease the uncertainty in the radiance responsivity transfer.

  11. Residual bias in a multiphase flow model calibration and prediction

    USGS Publications Warehouse

    Poeter, E.P.; Johnson, R.H.

    2002-01-01

    When calibrated models produce biased residuals, we assume it is due to an inaccurate conceptual model and revise the model, choosing the most representative model as the one with the best-fit and least biased residuals. However, if the calibration data are biased, we may fail to identify an acceptable model or choose an incorrect model. Conceptual model revision could not eliminate biased residuals during inversion of simulated DNAPL migration under controlled conditions at the Borden Site near Ontario Canada. This paper delineates hypotheses for the source of bias, and explains the evolution of the calibration and resulting model predictions.

  12. Approaches on calibration of bolometer and establishment of bolometer calibration device

    NASA Astrophysics Data System (ADS)

    Xia, Ming; Gao, Jianqiang; Ye, Jun'an; Xia, Junwen; Yin, Dejin; Li, Tiecheng; Zhang, Dong

    2015-10-01

    Bolometer is mainly used for measuring thermal radiation in the field of public places, labor hygiene, heating and ventilation and building energy conservation. The working principle of bolometer is under the exposure of thermal radiation, temperature of black absorbing layer of detector rise after absorption of thermal radiation, which makes the electromotive force produced by thermoelectric. The white light reflective layer of detector does not absorb thermal radiation, so the electromotive force produced by thermoelectric is almost zero. A comparison of electromotive force produced by thermoelectric of black absorbing layer and white reflective layer can eliminate the influence of electric potential produced by the basal background temperature change. After the electromotive force which produced by thermal radiation is processed by the signal processing unit, the indication displays through the indication display unit. The measurement unit of thermal radiation intensity is usually W/m2 or kW/m2. Its accurate and reliable value has important significance for high temperature operation, labor safety and hygiene grading management. Bolometer calibration device is mainly composed of absolute radiometer, the reference light source, electric measuring instrument. Absolute radiometer is a self-calibration type radiometer. Its working principle is using the electric power which can be accurately measured replaces radiation power to absolutely measure the radiation power. Absolute radiometer is the standard apparatus of laser low power standard device, the measurement traceability is guaranteed. Using the calibration method of comparison, the absolute radiometer and bolometer measure the reference light source in the same position alternately which can get correction factor of irradiance indication. This paper is mainly about the design and calibration method of the bolometer calibration device. The uncertainty of the calibration result is also evaluated.

  13. Absolute Calibration Accuracy for Hyperspectral Imagers in the Solar Reflective

    NASA Technical Reports Server (NTRS)

    Thome, Kurtis

    2009-01-01

    The characterization and calibration of hyperspectral imagers is a challenging one that is expected to become even more challenging as needs increase for highly-accurate radiometric data from such systems. The preflight calibration of the Advanced Responsive Tactically Effective Military Imaging Spectrometer (ARTEMIS) is used as an example of the difficulties to calibrate hyperspectrally. Results from a preflight solar radiation-based calibration are presented with a discussion of the uncertainties in such a method including the NISI-traceable and SItraceable aspects. Expansion on the concept of solar-based calibration is given with descriptions of methods that view the solar disk directly, illuminate a solar diffuser that is part of the sensor's inflight calibration, and illuminate an external diffuser that is imaged by the sensor. The results of error analysis show that it is feasible to achieve preflight calibration using the sun as a source at the same level of uncertainty as those of lamp-based approaches. The error analysis is evaluated and verified through the solar-radiation-based calibration of several of laboratory grade radiometers. Application of these approaches to NASA's upcoming CLARREO mission are discussed including proposed methods for significantly reducing the uncertainties to allow CLARREO data to be used for climate data records.

  14. Humidity effects on calibrations of radiation therapy electrometers

    SciTech Connect

    Downton, B.; Walker, S.

    2012-02-15

    Purpose: To eliminate variation in electrometer calibration results caused by high humidity and suboptimal connectors on the standard capacitors and to implement hardware that prevents overloading of the input stage of electrometers during calibration. Methods: A humidity-controlled cabinet was installed to provide a low-humidity environment for the standard capacitors. All of the coaxial BNC connections were replaced with Triax (TRB) connectors with the exception of the output from the voltage source. A three-stage RC filter with cascaded RC low-pass sections was designed and tested. Results: The installation of the humidity cabinet resulted in a major improvement in the stability and reproducibility of the electrometer calibration system. For the three years since this upgrade, the Ionizing Radiation Standards (IRS) electrometer calibration results have been consistent regardless of the ambient relative humidity in the lab. The connector replacements improved grounding in the calibration circuit. The three-stage filter allows the voltage at the output to rise in an S-shaped waveform, resulting in a smooth rise of the current through the isolation resistor from zero and back again, with no abrupt transition. For the filter design chosen, 99.99% of the charge is delivered within 6 s. Conclusions: A three-way improvement to the calibration measurement system was successful in eliminating the observed variations, resulting in an electrometer calibration measurement system that is unaffected by humidity and allowing reliable year-round calibrations of any electrometer encountered since the implementation of these changes.

  15. Visible Imaging Fourier Transform Spectrometer: Design and Calibration

    SciTech Connect

    Wishnow, E H; Wurtz, R; Blais-Ouellette, S; Cook, K H; Carr, D; Lewis, I; Grandmont, F; Stubbs, C W

    2002-09-19

    We present details of the design, operation and calibration of an astronomical visible-band imaging Fourier transform spectrometer (IFTS). This type of instrument produces a spectrum for every pixel in the field of view where the spectral resolution is flexible. The instrument is a dual-input/dual-output Michelson interferometer coupled to the 3.5 meter telescope at the Apache Point Observatory. Imaging performance and interferograms and spectra from calibration sources and standard stars are discussed.

  16. CP-50 calibration facility radiological safety assessment document

    SciTech Connect

    Chilton, M.W.; Hill, R.L.; Eubank, B.F.

    1980-03-01

    The CP-50 Calibration Facility Radiological Safety Assessment document, prepared at the request of the Nevada Operations Office of the US Department of Energy to satisfy provisions of ERDA Manual Chapter 0531, presents design features, systems controls, and procedures used in the operation of the calibration facility. Site and facility characteristics and routine and non-routine operations, including hypothetical incidents or accidents are discussed and design factors, source control systems, and radiation monitoring considerations are described.

  17. NASA Metrology and Calibration, 1980

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The proceedings of the fourth annual NASA Metrology and Calibration Workshop are presented. This workshop covered (1) review and assessment of NASA metrology and calibration activities by NASA Headquarters, (2) results of audits by the Office of Inspector General, (3) review of a proposed NASA Equipment Management System, (4) current and planned field center activities, (5) National Bureau of Standards (NBS) calibration services for NASA, (6) review of NBS's Precision Measurement and Test Equipment Project activities, (7) NASA instrument loan pool operations at two centers, (8) mobile cart calibration systems at two centers, (9) calibration intervals and decals, (10) NASA Calibration Capabilities Catalog, and (11) development of plans and objectives for FY 1981. Several papers in this proceedings are slide presentations only.

  18. 10 CFR 35.2632 - Records of teletherapy, remote afterloader, and gamma stereotactic radiosurgery full calibrations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Records of teletherapy, remote afterloader, and gamma stereotactic radiosurgery full calibrations. 35.2632 Section 35.2632 Energy NUCLEAR REGULATORY COMMISSION... stereotactic radiosurgery unit(s), the source(s), and the instruments used to calibrate the unit(s); (3)...

  19. Internal Water Vapor Photoacoustic Calibration

    NASA Technical Reports Server (NTRS)

    Pilgrim, Jeffrey S.

    2009-01-01

    Water vapor absorption is ubiquitous in the infrared wavelength range where photoacoustic trace gas detectors operate. This technique allows for discontinuous wavelength tuning by temperature-jumping a laser diode from one range to another within a time span suitable for photoacoustic calibration. The use of an internal calibration eliminates the need for external calibrated reference gases. Commercial applications include an improvement of photoacoustic spectrometers in all fields of use.

  20. Simulations toward Effective Calibrations of the CUORE Detector

    NASA Astrophysics Data System (ADS)

    Daniel, Byron; Cuore Collaboration

    2016-09-01

    It is currently unknown whether or not the neutrino is a MAJORANA or Dirac particle, that is, whether or not the neutrino is its own antiparticle. Observing neutrinoless double-beta decay, a process only possible if neutrinos are MAJORANA particles, can answer this question. If observed, this process would indicate that Lepton number is not conserved. CUORE's (Cryogenic Underground Observatory for Rare Events) is a bolometer based detector with Te02 crystal bolometers that is used to search for neutrinoless double-beta decay in 130Te. To insure that this detector will identify the energy peaks resulting from neutrinoless double-beta decay precisely, the detectors must be calibrated with gamma sources. To calibrate the detector, twelve strings carrying the calibration source 232Th were cooled from 300K to 10mK and installed within and around the bolometer towers. Six strings are distributed around the outside of the towers, and six strings are among the towers. This organization of strings was chosen because the gamma ray radiation from the source strings cannot penetrate more than one or two crystals at low energy. I will present the results from Monte Carlo simulations run in order to understand how to calibrate the COURE detector during operations and how to calibrate the CUORE detector in circumstances where the twelve calibration strings fail to deploy properly. Maruyama Group / CUORE collaboration.

  1. Comparison of spectral radiance responsivity calibration techniques used for backscatter ultraviolet satellite instruments

    NASA Astrophysics Data System (ADS)

    Kowalewski, M. G.; Janz, S. J.

    2015-02-01

    Methods of absolute radiometric calibration of backscatter ultraviolet (BUV) satellite instruments are compared as part of an effort to minimize pre-launch calibration uncertainties. An internally illuminated integrating sphere source has been used for the Shuttle Solar BUV, Total Ozone Mapping Spectrometer, Ozone Mapping Instrument, and Global Ozone Monitoring Experiment 2 using standardized procedures traceable to national standards. These sphere-based spectral responsivities agree to within the derived combined standard uncertainty of 1.87% relative to calibrations performed using an external diffuser illuminated by standard irradiance sources, the customary spectral radiance responsivity calibration method for BUV instruments. The combined standard uncertainty for these calibration techniques as implemented at the NASA Goddard Space Flight Center’s Radiometric Calibration and Development Laboratory is shown to less than 2% at 250 nm when using a single traceable calibration standard.

  2. Neural networks for calibration tomography

    NASA Technical Reports Server (NTRS)

    Decker, Arthur

    1993-01-01

    Artificial neural networks are suitable for performing pattern-to-pattern calibrations. These calibrations are potentially useful for facilities operations in aeronautics, the control of optical alignment, and the like. Computed tomography is compared with neural net calibration tomography for estimating density from its x-ray transform. X-ray transforms are measured, for example, in diffuse-illumination, holographic interferometry of fluids. Computed tomography and neural net calibration tomography are shown to have comparable performance for a 10 degree viewing cone and 29 interferograms within that cone. The system of tomography discussed is proposed as a relevant test of neural networks and other parallel processors intended for using flow visualization data.

  3. Atmospheric optical calibration system

    DOEpatents

    Hulstrom, R.L.; Cannon, T.W.

    1988-10-25

    An atmospheric optical calibration system is provided to compare actual atmospheric optical conditions to standard atmospheric optical conditions on the basis of aerosol optical depth, relative air mass, and diffuse horizontal skylight to global horizontal photon flux ratio. An indicator can show the extent to which the actual conditions vary from standard conditions. Aerosol scattering and absorption properties, diffuse horizontal skylight to global horizontal photon flux ratio, and precipitable water vapor determined on a real-time basis for optical and pressure measurements are also used to generate a computer spectral model and for correcting actual performance response of a photovoltaic device to standard atmospheric optical condition response on a real-time basis as the device is being tested in actual outdoor conditions. 7 figs.

  4. Atmospheric optical calibration system

    DOEpatents

    Hulstrom, Roland L.; Cannon, Theodore W.

    1988-01-01

    An atmospheric optical calibration system is provided to compare actual atmospheric optical conditions to standard atmospheric optical conditions on the basis of aerosol optical depth, relative air mass, and diffuse horizontal skylight to global horizontal photon flux ratio. An indicator can show the extent to which the actual conditions vary from standard conditions. Aerosol scattering and absorption properties, diffuse horizontal skylight to global horizontal photon flux ratio, and precipitable water vapor determined on a real-time basis for optical and pressure measurements are also used to generate a computer spectral model and for correcting actual performance response of a photovoltaic device to standard atmospheric optical condition response on a real-time basis as the device is being tested in actual outdoor conditions.

  5. Inspection system calibration methods

    DOEpatents

    Deason, Vance A.; Telschow, Kenneth L.

    2004-12-28

    An inspection system calibration method includes producing two sideband signals of a first wavefront; interfering the two sideband signals in a photorefractive material, producing an output signal therefrom having a frequency and a magnitude; and producing a phase modulated operational signal having a frequency different from the output signal frequency, a magnitude, and a phase modulation amplitude. The method includes determining a ratio of the operational signal magnitude to the output signal magnitude, determining a ratio of a 1st order Bessel function of the operational signal phase modulation amplitude to a 0th order Bessel function of the operational signal phase modulation amplitude, and comparing the magnitude ratio to the Bessel function ratio.

  6. Quality Management and Calibration

    NASA Astrophysics Data System (ADS)

    Merkus, Henk G.

    Good specification of a product’s performance requires adequate characterization of relevant properties. Particulate products are usually characterized by some PSD, shape or porosity parameter(s). For proper characterization, adequate sampling, dispersion, and measurement procedures should be available or developed and skilful personnel should use appropriate, well-calibrated/qualified equipment. The characterization should be executed, in agreement with customers, in a wellorganized laboratory. All related aspects should be laid down in a quality handbook. The laboratory should provide proof for its capability to perform the characterization of stated products and/or reference materials within stated confidence limits. This can be done either by internal validation and audits or by external GLP accreditation.

  7. TOD to TTP calibration

    NASA Astrophysics Data System (ADS)

    Bijl, Piet; Reynolds, Joseph P.; Vos, Wouter K.; Hogervorst, Maarten A.; Fanning, Jonathan D.

    2011-05-01

    The TTP (Targeting Task Performance) metric, developed at NVESD, is the current standard US Army model to predict EO/IR Target Acquisition performance. This model however does not have a corresponding lab or field test to empirically assess the performance of a camera system. The TOD (Triangle Orientation Discrimination) method, developed at TNO in The Netherlands, provides such a measurement. In this study, we make a direct comparison between TOD performance for a range of sensors and the extensive historical US observer performance database built to develop and calibrate the TTP metric. The US perception data were collected doing an identification task by military personnel on a standard 12 target, 12 aspect tactical vehicle image set that was processed through simulated sensors for which the most fundamental sensor parameters such as blur, sampling, spatial and temporal noise were varied. In the present study, we measured TOD sensor performance using exactly the same sensors processing a set of TOD triangle test patterns. The study shows that good overall agreement is obtained when the ratio between target characteristic size and TOD test pattern size at threshold equals 6.3. Note that this number is purely based on empirical data without any intermediate modeling. The calibration of the TOD to the TTP is highly beneficial to the sensor modeling and testing community for a variety of reasons. These include: i) a connection between requirement specification and acceptance testing, and ii) a very efficient method to quickly validate or extend the TTP range prediction model to new systems and tasks.

  8. Calibration of the MEDUSA neutron spectrometer (abstract)

    SciTech Connect

    Sangster, T. C.; Glebov, V. Yu.; Lerche, R. A.; Phillips, T. W.; Stoeckl, C.; Padalino, S. J.; Olliver, H.; Thompson, S.

    2001-01-01

    The MEDUSA array is a multielement, scintillator-based neutron time-of-flight spectrometer designed primarily to measure primary and secondary neutron production from indirect drive DD and DT capsule implosions at the Omega Laser in Rochester, NY. The array consists of 824 identical scintillator-photomultiplier tube detectors coupled to analog signal discriminators and high resolution, multihit time-to-digital converters, and is located 19.4 m from the center of the Omega target chamber. It is possible to accurately measure the neutron energy spectrum by simply measuring an adequate sample of neutron flight times to the array (the burn time width is negligible). However it is essential to understand the response of the array detectors to the fusion neutrons before an energy spectrum can be deduced from the data. This array response function is generally given in terms of a calibration constant that relates the expected number of detector hits in the array to the number of source neutrons. The calibration constant is a function of the individual detector gains, the thresholds of the discriminators, and the amount of neutron attenuating material between the array and the target. After gain matching the detectors, a calibration constant can be generated by comparing the array response against a known yield of neutrons (this requires dozens of implosions) or from a first principles measurement of the individual detector efficiencies. In this article, we report on the results of both calibrations of the MEDUSA array. In particular, we will focus on the issues and errors associated with the very different measurements required and discuss a new technique being considered for rapid in situ future calibrations.

  9. SWIR calibration of Spectralon reflectance factor

    NASA Astrophysics Data System (ADS)

    Georgiev, Georgi T.; Butler, James J.; Cooksey, Catherine; Ding, Leibo; Thome, Kurtis J.

    2011-11-01

    Satellite instruments operating in the reflective solar wavelength region require accurate and precise determination of the Bidirectional Reflectance Factor (BRF) of laboratory-based diffusers used in their pre-flight and on-orbit radiometric calibrations. BRF measurements are required throughout the reflected-solar spectrum from the ultraviolet through the shortwave infrared. Spectralon diffusers are commonly used as a reflectance standard for bidirectional and hemispherical geometries. The Diffuser Calibration Laboratory (DCaL) at NASA's Goddard Space Flight Center is a secondary calibration facility with reflectance measurements traceable to those made by the Spectral Tri-function Automated Reference Reflectometer (STARR) facility at the National Institute of Standards and Technology (NIST). For more than two decades, the DCaL has provided numerous NASA projects with BRF data in the ultraviolet (UV), visible (VIS) and the Near InfraRed (NIR) spectral regions. Presented in this paper are measurements of BRF from 1475 nm to 1625 nm obtained using an indium gallium arsenide detector and a tunable coherent light source. The sample was a 50.8 mm (2 in) diameter, 99% white Spectralon target. The BRF results are discussed and compared to empirically generated data from a model based on NIST certified values of 6°directional-hemispherical spectral reflectance factors from 900 nm to 2500 nm. Employing a new NIST capability for measuring bidirectional reflectance using a cooled, extended InGaAs detector, BRF calibration measurements of the same sample were also made using NIST's STARR from 1475 nm to 1625 nm at an incident angle of 0° and at viewing angle of 45°. The total combined uncertainty for BRF in this ShortWave Infrared (SWIR) range is less than 1%. This measurement capability will evolve into a BRF calibration service in SWIR region in support of NASA remote sensing missions.

  10. Equipment for the calibration of squareness standards

    NASA Astrophysics Data System (ADS)

    Hemming, Björn; Korhonen, Antti; Palosuo, Ilkka; Lassila, Antti

    2012-09-01

    In dimensional metrology, the measurement of squareness is a basic task for many purposes. At the Centre for Metrology and Accreditation (MIKES), a squareness measuring machine for traceable calibration of squares has been developed. The machine is able to measure a squareness standard of 1000 mm × 1000 mm maximum size. The system consists of a rotary table and a tactile displacement transducer with horizontal and vertical linear guides. The error sources of the developed equipment are presented together with a brief description of the calibration procedure. Implemented error compensation of the rotary table and one linear guide is described. The uncertainty estimate is presented for squareness angle measurement. The standard measurement uncertainty for steel or granite squares is 0.2″. We also present the results of an internal comparison of squareness measurements made with the developed machine and a high accuracy coordinate measuring machine. The results show good agreement.

  11. Calibration of optical particle-size analyzer

    DOEpatents

    Pechin, William H.; Thacker, Louis H.; Turner, Lloyd J.

    1979-01-01

    This invention relates to a system for the calibration of an optical particle-size analyzer of the light-intercepting type for spherical particles, wherein a rotary wheel or disc is provided with radially-extending wires of differing diameters, each wire corresponding to a particular equivalent spherical particle diameter. These wires are passed at an appropriate frequency between the light source and the light detector of the analyzer. The reduction of light as received at the detector is a measure of the size of the wire, and the electronic signal may then be adjusted to provide the desired signal for corresponding spherical particles. This calibrator may be operated at any time without interrupting other processing.

  12. Construction and operation of an improved radiation calibration facility at Brookhaven National Laboratory. Environmental assessment

    SciTech Connect

    1994-10-01

    Calibration of instruments used to detect and measure ionizing radiation has been conducted over the last 20 years at Brookhaven National Laboratory`s (BNL) Radiation Calibration Facility, Building 348. Growth of research facilities, projects in progress, and more stringent Department of Energy (DOE) orders which involve exposure to nuclear radiation have placed substantial burdens on the existing radiation calibration facility. The facility currently does not meet the requirements of DOE Order 5480.4 or American National Standards Institute (ANSI) N323-1978, which establish calibration methods for portable radiation protection instruments used in the detection and measurement of levels of ionizing radiation fields or levels of radioactive surface contaminations. Failure to comply with this standard could mean instrumentation is not being calibrated to necessary levels of sensitivity. The Laboratory has also recently obtained a new neutron source and gamma beam irradiator which can not be made operational at existing facilities because of geometry and shielding inadequacies. These sources are needed to perform routine periodic calibrations of radiation detecting instruments used by scientific and technical personnel and to meet BNL`s substantial increase in demand for radiation monitoring capabilities. To place these new sources into operation, it is proposed to construct an addition to the existing radiation calibration facility that would house all calibration sources and bring BNL calibration activities into compliance with DOE and ANSI standards. The purpose of this assessment is to identify potential significant environmental impacts associated with the construction and operation of an improved radiation calibration facility at BNL.

  13. Robust calibration of a global aerosol model

    NASA Astrophysics Data System (ADS)

    Lee, L.; Carslaw, K. S.; Pringle, K. J.; Reddington, C.

    2013-12-01

    Comparison of models and observations is vital for evaluating how well computer models can simulate real world processes. However, many current methods are lacking in their assessment of the model uncertainty, which introduces questions regarding the robustness of the observationally constrained model. In most cases, models are evaluated against observations using a single baseline simulation considered to represent the models' best estimate. The model is then improved in some way so that its comparison to observations is improved. Continuous adjustments in such a way may result in a model that compares better to observations but there may be many compensating features which make prediction with the newly calibrated model difficult to justify. There may also be some model outputs whose comparison to observations becomes worse in some regions/seasons as others improve. In such cases calibration cannot be considered robust. We present details of the calibration of a global aerosol model, GLOMAP, in which we consider not just a single model setup but a perturbed physics ensemble with 28 uncertain parameters. We first quantify the uncertainty in various model outputs (CCN, CN) for the year 2008 and use statistical emulation to identify which of the 28 parameters contribute most to this uncertainty. We then compare the emulated model simulations in the entire parametric uncertainty space to observations. Regions where the entire ensemble lies outside the error of the observations indicate structural model error or gaps in current knowledge which allows us to target future research areas. Where there is some agreement with the observations we use the information on the sources of the model uncertainty to identify geographical regions in which the important parameters are similar. Identification of regional calibration clusters helps us to use information from observation rich regions to calibrate regions with sparse observations and allow us to make recommendations for

  14. Improvements in dissemination of spectral irradiance calibrations

    NASA Astrophysics Data System (ADS)

    Kärhä, P.; Ylianttila, L.; Jokela, K.; Ikonen, E.

    2003-04-01

    Solar UV measurements have reached a level where uncertainties and discrepancies of standard lamps used for calibration of the spectroradiometers are already limiting factors in the measurements. Lamps purchased from different national standards laboratories often show discrepancies higher than the stated uncertainties when measured in solar UV intercomparison campaigns. One major source for the deviations between the lamps is changes of the lamp irradiance in transportation. Even if hand-carried, the lamps may be damaged by thermal or mechanical shocks. Short-circuiting of the coils causes spectrally dependent decrease of the spectral irradiance values. This effect can be detected, but not quantified, by monitoring the voltage across the lamp terminals. However, this monitoring does not reveal changes caused by bending of the filaments. At the Helsinki University of Technology (HUT), we have developed a portable primary standard of spectral irradiance based on characterised filter radiometers. The standard consists of a filter radiometer with 14 interchangeable narrow-band interference filters for the wavelength region 290 - 900 nm. The filter radiometer is packed in a flight case that allows its transportation to solar UV measurement sites. Thus, the use of the filter radiometer eliminates completely the need to transport lamps. The method has been tested in direct intercomparisons with PTB (Germany), NPL (UK) and NIST (USA). The results of the intercomparisons clearly verify the calculated uncertainties (2 sigma) that range between 2.7% and 1.5% in the solar UV region of 290 - 380 nm. The filter radiometer can also be used to calibrate a solar UV calibrator that has been developed in a collaboration project between HUT and STUK. This calibrator utilises a 1-kW DXW-type lamp that has been enclosed in robust aluminium housing. The lamp is monitored with two narrow-band UV filter radiometers. The calibrator can be assembled on top of any spectroradiometer by using

  15. A new polarimetric active radar calibrator and calibration technique

    NASA Astrophysics Data System (ADS)

    Tang, Jianguo; Xu, Xiaojian

    2015-10-01

    Polarimetric active radar calibrator (PARC) is one of the most important calibrators with high radar cross section (RCS) for polarimetry measurement. In this paper, a new double-antenna polarimetric active radar calibrator (DPARC) is proposed, which consists of two rotatable antennas with wideband electromagnetic polarization filters (EMPF) to achieve lower cross-polarization for transmission and reception. With two antennas which are rotatable around the radar line of sight (LOS), the DPARC provides a variety of standard polarimetric scattering matrices (PSM) through the rotation combination of receiving and transmitting polarization, which are useful for polarimatric calibration in different applications. In addition, a technique based on Fourier analysis is proposed for calibration processing. Numerical simulation results are presented to demonstrate the superior performance of the proposed DPARC and processing technique.

  16. A SVD-based method to assess the uniqueness and accuracy of SPECT geometrical calibration.

    PubMed

    Ma, Tianyu; Yao, Rutao; Shao, Yiping; Zhou, Rong

    2009-12-01

    Geometrical calibration is critical to obtaining high resolution and artifact-free reconstructed image for SPECT and CT systems. Most published calibration methods use analytical approach to determine the uniqueness condition for a specific calibration problem, and the calibration accuracy is often evaluated through empirical studies. In this work, we present a general method to assess the characteristics of both the uniqueness and the quantitative accuracy of the calibration. The method uses a singular value decomposition (SVD) based approach to analyze the Jacobian matrix from a least-square cost function for the calibration. With this method, the uniqueness of the calibration can be identified by assessing the nonsingularity of the Jacobian matrix, and the estimation accuracy of the calibration parameters can be quantified by analyzing the SVD components. A direct application of this method is that the efficacy of a calibration configuration can be quantitatively evaluated by choosing a figure-of-merit, e.g., the minimum required number of projection samplings to achieve desired calibration accuracy. The proposed method was validated with a slit-slat SPECT system through numerical simulation studies and experimental measurements with point sources and an ultra-micro hot-rod phantom. The predicted calibration accuracy from the numerical studies was confirmed by the experimental point source calibrations at approximately 0.1 mm for both the center of rotation (COR) estimation of a rotation stage and the slit aperture position (SAP) estimation of a slit-slat collimator by an optimized system calibration protocol. The reconstructed images of a hot rod phantom showed satisfactory spatial resolution with a proper calibration and showed visible resolution degradation with artificially introduced 0.3 mm COR estimation error. The proposed method can be applied to other SPECT and CT imaging systems to analyze calibration method assessment and calibration protocol

  17. Monte Carlo calculation of the sensitivity of a commercial dose calibrator to gamma and beta radiation.

    PubMed

    Laedermann, Jean-Pascal; Valley, Jean-François; Bulling, Shelley; Bochud, François O

    2004-06-01

    The detection process used in a commercial dose calibrator was modeled using the GEANT 3 Monte Carlo code. Dose calibrator efficiency for gamma and beta emitters, and the response to monoenergetic photons and electrons was calculated. The model shows that beta emitters below 2.5 MeV deposit energy indirectly in the detector through bremsstrahlung produced in the chamber wall or in the source itself. Higher energy beta emitters (E > 2.5 MeV) deposit energy directly in the chamber sensitive volume, and dose calibrator sensitivity increases abruptly for these radionuclides. The Monte Carlo calculations were compared with gamma and beta emitter measurements. The calculations show that the variation in dose calibrator efficiency with measuring conditions (source volume, container diameter, container wall thickness and material, position of the source within the calibrator) is relatively small and can be considered insignificant for routine measurement applications. However, dose calibrator efficiency depends strongly on the inner-wall thickness of the detector.

  18. BXS Re-calibration

    SciTech Connect

    Welch, J; /SLAC

    2010-11-24

    Early in the commissioning it was noticed by Cecile Limborg that the calibration of the BXS spectrometer magnet seemed to be different from the strength of the BX01/BX02 magnets. First the BX01/BX02 currents were adjusted to 135 MeV and the beam energy was adjusted to make the horizontal orbit flat. Then BX01/BX02 magnets were switched off and BXS was adjusted to make the horizontal orbit in the spectrometer line flat, without changing the energy of the beam. The result was that about 140-141 MeV were required on the BXS magnet. This measurement was repeated several times by others with the same results. It was not clear what was causing the error: magnet strength or layout. A position error of about 19 mm of the BXS magnet could explain the difference. Because there was a significant misalignment of the vacuum chamber in the BXS line, the alignment of the whole spectrometer line was checked. The vacuum chamber was corrected, but the magnets were found to be in the proper alignment. So we were left with one (or conceivably two) magnet calibration errors. Because BXS is a wedged shaped magnet, the bend angle depends on the horizontal position of the incoming beam. As mentioned, an offset of the beam position of 19 mm would increase or decrease the bend angle roughly by the ratio of 135/141. The figure of 19 mm is special and caused a considerable confusion during the design and measurement of the BXS magnet. This is best illustrated in Figure 1 which was taken out of the BXS Traveler document. The distance between the horizontal midplanes of the poles and the apex of the beam path was chosen to be 19 mm so the beam is close to the good field region throughout its entire path. Thus it seemed possible that there was an error that resulted in the beam not being on this trajectory, or conversely, that the magnetic measurements were done on the wrong trajectory and the magnet was then mis-calibrated. Mechanical measurements of the vacuum chamber made in the tunnel

  19. Automatic online spectral calibration of Fourier-domain OCT for robotic surgery

    NASA Astrophysics Data System (ADS)

    Liu, Xuan; Balicki, Marcin; Taylor, Russell H.; Kang, Jin U.

    2011-03-01

    We present a new automatic spectral calibration (ASC) method for spectral Domain optical coherence tomography (SD-OCT). Our ASC method calibrates the spectral mapping of the spectrometer in SD-OCT, and does not require external calibrating light source or a commercial spectral analyzer. The ASC method simultaneously calibrates the physical pixel spacing of the A-scan in static and dynamic environments. Experimental results show that the proposed ASC method can provide satisfactory calibration for SD-OCT to achieve high axial resolution and high ranging accuracy, without increasing hardware complexity.

  20. The KamLAND Full-Volume Calibration System

    SciTech Connect

    KamLAND Collaboration; Berger, B. E.; Busenitz, J.; Classen, T.; Decowski, M. P.; Dwyer, D. A.; Elor, G.; Frank, A.; Freedman, S. J.; Fujikawa, B. K.; Galloway, M.; Gray, F.; Heeger, K. M.; Hsu, L.; Ichimura, K.; Kadel, R.; Keefer, G.; Lendvai, C.; McKee, D.; O'Donnell, T.; Piepke, A.; Steiner, H. M.; Syversrud, D.; Wallig, J.; Winslow, L. A.; Ebihara, T.; Enomoto, S.; Furuno, K.; Gando, Y.; Ikeda, H.; Inoue, K.; Kibe, Y.; Kishimoto, Y.; Koga, M.; Minekawa, Y.; Mitsui, T.; Nakajima, K.; Nakajima, K.; Nakamura, K.; Owada, K.; Shimizu, I.; Shimizu, Y.; Shirai, J.; Suekane, F.; Suzuki, A.; Tamae, K.; Yoshida, S.; Kozlov, A.; Murayama, H.; Grant, C.; Leonard, D. S.; Luk, K.-B.; Jillings, C.; Mauger, C.; McKeown, R. D.; Zhang, C.; Lane, C. E.; Maricic, J.; Miletic, T.; Batygov, M.; Learned, J. G.; Matsuno, S.; Pakvasa, S.; Foster, J.; Horton-Smith, G. A.; Tang, A.; Dazeley, S.; Downum, K. E.; Gratta, G.; Tolich, K.; Bugg, W.; Efremenko, Y.; Kamyshkov, Y.; Perevozchikov, O.; Karwowski, H. J.; Markoff, D. M.; Tornow, W.; Piquemal, F.; Ricol, J.-S.

    2009-03-05

    We have successfully built and operated a source deployment system for the KamLAND detector. This system was used to position radioactive sources throughout the delicate 1-kton liquid scintillator volume, while meeting stringent material cleanliness, material compatibility, and safety requirements. The calibration data obtained with this device were used to fully characterize detector position and energy reconstruction biases. As a result, the uncertainty in the size of the detector fiducial volume was reduced by a factor of two. Prior to calibration with this system, the fiducial volume was the largest source of systematic uncertainty in measuring the number of antineutrinos detected by KamLAND. This paper describes the design, operation and performance of this unique calibration system.

  1. Calibration of the ARID robot

    NASA Technical Reports Server (NTRS)

    Doty, Keith L

    1992-01-01

    The author has formulated a new, general model for specifying the kinematic properties of serial manipulators. The new model kinematic parameters do not suffer discontinuities when nominally parallel adjacent axes deviate from exact parallelism. From this new theory the author develops a first-order, lumped-parameter, calibration-model for the ARID manipulator. Next, the author develops a calibration methodology for the ARID based on visual and acoustic sensing. A sensor platform, consisting of a camera and four sonars attached to the ARID end frame, performs calibration measurements. A calibration measurement consists of processing one visual frame of an accurately placed calibration image and recording four acoustic range measurements. A minimum of two measurement protocols determine the kinematics calibration-model of the ARID for a particular region: assuming the joint displacements are accurately measured, the calibration surface is planar, and the kinematic parameters do not vary rapidly in the region. No theoretical or practical limitations appear to contra-indicate the feasibility of the calibration method developed here.

  2. Side looking radar calibration study

    NASA Technical Reports Server (NTRS)

    Edwards, W. D.

    1975-01-01

    Calibration of an airborne sidelooking radar is accomplished by the use of a model that relates the radar parameters to the physical mapping situation. Topics discussed include: characteristics of the transmitters; the antennas; target absorption and reradiation; the receiver and map making or radar data processing; and the calibration process.

  3. Absolute Calibration of the AXAF Telescope Effective Area

    NASA Technical Reports Server (NTRS)

    Kellogg, E.; Cohen, L.; Edgar, R.; Evans, I.; Freeman, M.; Gaetz, T.; Jerius, D.; McDermott, W. C.; McKinnon, P.; Murray, S.; Podgorski, W.; Schwartz, D.; VanSpeybroeck, L.; Wargelin, B.; Zombeck, M.; Weisskopf, M.; Elsner, R.; ODell, S.; Tennant, A.; Kolodziejczak, J.

    1997-01-01

    The prelaunch calibration of AXAF encompasses many aspects of the telescope. In principle, all that is needed is the complete point response function. This is, however, a function of energy, off-axis angle of the source, and operating mode of the facility. No single measurement would yield the entire result. Also, any calibration made prior to launch will be affected by changes in conditions after launch, such as the change from one g to zero g. The reflectivity of the mirror and perhaps even the detectors can change as well, for example by addition or removal of small amounts of material deposited on their surfaces. In this paper, we give a broad view of the issues in performing such a calibration, and discuss how they are being addressed in prelaunch preparation of AXAF. As our title indicates, we concentrate here on the total throughput of the observatory. This can be thought of as the integral of the point response function, i.e. the encircled energy, out ot the largest practical solid angle for an observation. Since there is no standard x-ray source in the sky whose flux is known to the -1% accuracy we are trying to achieve, we must do this calibration on the ground. we also must provide a means for monitoring any possible changes in this calibration from pre-launch until on-orbit operation can transfer the calibration to a celestial x-ray source whose emission is stable. In this paper, we analyze the elements of the absolute throughput calibration, which we call Effective Area. We review the requirements for calibrations of components or subsystems of the AXAF facility, including mirror, detectors, and gratings. We show how it is necessary to calibrate this ground-based detection system at standard man-made x-ray sources, such as electron storage rings. We present the status of all these calibrations, with indications of the measurements remaining to be done, even though the measurements on the AXAF flight optics and detectors will have been completed by the

  4. TIME CALIBRATED OSCILLOSCOPE SWEEP CIRCUIT

    DOEpatents

    Smith, V.L.; Carstensen, H.K.

    1959-11-24

    An improved time calibrated sweep circuit is presented, which extends the range of usefulness of conventional oscilloscopes as utilized for time calibrated display applications in accordance with U. S. Patent No. 2,832,002. Principal novelty resides in the provision of a pair of separate signal paths, each of which is phase and amplitude adjustable, to connect a high-frequency calibration oscillator to the output of a sawtooth generator also connected to the respective horizontal deflection plates of an oscilloscope cathode ray tube. The amplitude and phase of the calibration oscillator signals in the two signal paths are adjusted to balance out feedthrough currents capacitively coupled at high frequencies of the calibration oscillator from each horizontal deflection plate to the vertical plates of the cathode ray tube.

  5. Calibration of platinum resistance thermometers.

    NASA Technical Reports Server (NTRS)

    Sinclair, D. H.; Terbeek, H. G.; Malone, J. H.

    1972-01-01

    Results of five years experience in calibrating about 1000 commercial platinum resistance thermometers (PRT) are reported. These PRT were relatively small and rugged, with ice-point resistances from 200 to 5000 ohms. Calibrations normalized in terms of resistance-difference ratios (Cragoe Z function) were found to be remarkably uniform for five of six different types of PRT tested, and to agree very closely with normalized calibrations of the primary reference standard type PRT. The Z function normalization cancels residual resistances which are not temperature dependent and simplifies interpolation between calibration points when the quality of a given type of PRT has been established in terms of uniform values of the Z function. Measurements at five or six well spaced base-point temperatures with Z interpolation will suffice to calibrate a PRT accurately from 4 to 900 K.

  6. Antenna Calibration and Measurement Equipment

    NASA Technical Reports Server (NTRS)

    Rochblatt, David J.; Cortes, Manuel Vazquez

    2012-01-01

    A document describes the Antenna Calibration & Measurement Equipment (ACME) system that will provide the Deep Space Network (DSN) with instrumentation enabling a trained RF engineer at each complex to perform antenna calibration measurements and to generate antenna calibration data. This data includes continuous-scan auto-bore-based data acquisition with all-sky data gathering in support of 4th order pointing model generation requirements. Other data includes antenna subreflector focus, system noise temperature and tipping curves, antenna efficiency, reports system linearity, and instrument calibration. The ACME system design is based on the on-the-fly (OTF) mapping technique and architecture. ACME has contributed to the improved RF performance of the DSN by approximately a factor of two. It improved the pointing performances of the DSN antennas and productivity of its personnel and calibration engineers.

  7. Thoughts on VCD-145 Detector Calibration

    SciTech Connect

    Morgan, W V

    2005-02-10

    In 1980, Don Smith requested that the EG&G Detector Group in North Las Vegas provide a summary of calibrated sensitivities for the VCD-145 detector. The &sired information was provided in a memorandum from Sam Egdorf (Reference 1). A memo from Brent Davis issued a week later described the effect on VCD-145 detector sensitivity that resulted from changing the thickness of the stainless steel entrance window (Reference 2). This memo is intended first to effectively archive those two references, and second to record thoughts about the significance of their contents. Reference 1 lists a total of 118 calibrated values for 80 different VCD-145 detectors, from 1977 to 1980. With only four exceptions, all of the serial numbers from V004 to V087 were included. The earlier calibrations were for detectors with 1-mil entrance windows, and the later ones were for detectors with 2-mil entrance windows. Three of the earlier units were calibrated at both thicknesses by temporarily placing an extra 1-mil sheet of stainless steel across the window. Altogether six different collimator diameters were used, from 60 mm to 95 mm. Some units were calibrated for more than one collimator diameter, and 14 were at some point designated as backup detectors for a second event. Reference 2 describes the effect of window thickness on calibrated sensitivity. Quoting that reference: ''To demonstrate that the sensitivity decrease is solely a function of the window thickness, a standard VCD-145 detector with a 0.001-inch thick window was calibrated with the {sup 60}Co source. Then without changing detector or geometry, a 0.001 -inch thick stainless steel foil (same material as that of the window) was placed directly in front of the detector window, effectively making a 0.002-inch thick entrance window. The detector was again calibrated. This technique was repeated until the detector had an entrance window equivalent to 0.010-inches thick.'' There are multiple reasons to suspect that the accuracy of

  8. VIEW OF BUILDING 126, LOOKING NORTH. BUILDING 126, THE SOURCE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF BUILDING 126, LOOKING NORTH. BUILDING 126, THE SOURCE CALIBRATION LABORATORY, WAS USED TO EXPOSE AND CALIBRATE RADIATION DETECTION DEVICES, INCLUDING THERMOLUMINESCENT DOSIMETERS, WORN BY EMPLOYEES TO DETECT RADIATION EXPOSURE - Rocky Flats Plant, Source Calibration Laboratory, Between Second & Third Streets & Central & Cedar Avenues, Golden, Jefferson County, CO

  9. A calibrated Franklin chimes

    NASA Astrophysics Data System (ADS)

    Gonta, Igor; Williams, Earle

    1994-05-01

    Benjamin Franklin devised a simple yet intriguing device to measure electrification in the atmosphere during conditions of foul weather. He constructed a system of bells, one of which was attached to a conductor that was suspended vertically above his house. The device is illustrated in a well-known painting of Franklin (Cohen, 1985). The elevated conductor acquired a potential due to the electric field in the atmosphere and caused a brass ball to oscillate between two bells. The purpose of this study is to extend Franklin's idea by constructing a set of 'chimes' which will operate both in fair and in foul weather conditions. In addition, a mathematical relationship will be established between the frequency of oscillation of a metallic sphere in a simplified geometry and the potential on one plate due to the electrification of the atmosphere. Thus it will be possible to calibrate the 'Franklin Chimes' and to obtain a nearly instantaneous measurement of the potential of the elevated conductor in both fair and foul weather conditions.

  10. Diode calibration manual

    SciTech Connect

    Brunk, J.L.

    1989-09-01

    This procedure is not for the faint of heart. It is a time consuming, complex series of journeys through advanced GAMANAL and the vagueness of analyzer electronics. A knowledge of TRIX AC, DLTV, and IMP on the Octopus system and DSCOPE, PE2, and Symphony on a PC class machine is required. Be aware that the example in this document is a condensation of information that takes up four feet of shelf space. In the attempt to convert the nomenclature of the 7600 version of GAMANAL to that of the CRAY version, there will be confusion with some of the terms used. The 7600 versions relied on punched cards to a great extent where the CRAY version doesn't use them at all. In order not to introduce a new set of nomenclature, I have changed the reference from card to card image. I hope that this will cause the least impact on the vernacular and cause the least amount of confusion possible. This document is a rewritten update of an unpublished document by Bob Wikkerink in 1980. His document was the only written record of the procedures needed to calibrate the Environmental Sciences Low Level Counting Facility. This document updates and expands this information.

  11. Development and Characterization of a Low-Pressure Calibration System for Hypersonic Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Green, Del L.; Everhart, Joel L.; Rhode, Matthew N.

    2004-01-01

    Minimization of uncertainty is essential for accurate ESP measurements at very low free-stream static pressures found in hypersonic wind tunnels. Statistical characterization of environmental error sources requires a well defined and controlled calibration method. A calibration system has been constructed and environmental control software developed to control experimentation to eliminate human induced error sources. The initial stability study of the calibration system shows a high degree of measurement accuracy and precision in temperature and pressure control. Control manometer drift and reference pressure instabilities induce uncertainty into the repeatability of voltage responses measured from the PSI System 8400 between calibrations. Methods of improving repeatability are possible through software programming and further experimentation.

  12. Multi-fidelity approach to dynamics model calibration

    NASA Astrophysics Data System (ADS)

    Absi, Ghina N.; Mahadevan, Sankaran

    2016-02-01

    This paper investigates the use of structural dynamics computational models with multiple levels of fidelity in the calibration of system parameters. Different types of models may be available for the estimation of unmeasured system properties, with different levels of physics fidelity, mesh resolution and boundary condition assumptions. In order to infer these system properties, Bayesian calibration uses information from multiple sources (including experimental data and prior knowledge), and comprehensively quantifies the uncertainty in the calibration parameters. Estimating the posteriors is done using Markov Chain Monte Carlo sampling, which requires a large number of computations, thus making the use of a high-fidelity model for calibration prohibitively expensive. On the other hand, use of a low-fidelity model could lead to significant error in calibration and prediction. Therefore, this paper develops an approach for model parameter calibration with a low-fidelity model corrected using higher fidelity simulations, and investigates the trade-off between accuracy and computational effort. The methodology is illustrated for a curved panel located in the vicinity of a hypersonic aircraft engine, subjected to acoustic loading. Two models (a frequency response analysis and a full time history analysis) are combined to calibrate the damping characteristics of the panel.

  13. Calibration of Correlation Radiometers Using Pseudo-Random Noise Signals

    PubMed Central

    Pérez, Isaac Ramos; Bosch-Lluis, Xavi; Camps, Adriano; Alvarez, Nereida Rodriguez; Hernandez, Juan Fernando Marchán; Domènech, Enric Valencia; Vernich, Carlos; de la Rosa, Sonia; Pantoja, Sebastián

    2009-01-01

    The calibration of correlation radiometers, and particularly aperture synthesis interferometric radiometers, is a critical issue to ensure their performance. Current calibration techniques are based on the measurement of the cross-correlation of receivers’ outputs when injecting noise from a common noise source requiring a very stable distribution network. For large interferometric radiometers this centralized noise injection approach is very complex from the point of view of mass, volume and phase/amplitude equalization. Distributed noise injection techniques have been proposed as a feasible alternative, but are unable to correct for the so-called “baseline errors” associated with the particular pair of receivers forming the baseline. In this work it is proposed the use of centralized Pseudo-Random Noise (PRN) signals to calibrate correlation radiometers. PRNs are sequences of symbols with a long repetition period that have a flat spectrum over a bandwidth which is determined by the symbol rate. Since their spectrum resembles that of thermal noise, they can be used to calibrate correlation radiometers. At the same time, since these sequences are deterministic, new calibration schemes can be envisaged, such as the correlation of each receiver’s output with a baseband local replica of the PRN sequence, as well as new distribution schemes of calibration signals. This work analyzes the general requirements and performance of using PRN sequences for the calibration of microwave correlation radiometers, and particularizes the study to a potential implementation in a large aperture synthesis radiometer using an optical distribution network. PMID:22454576

  14. Systematic Calibration for Ultra-High Accuracy Inertial Measurement Units.

    PubMed

    Cai, Qingzhong; Yang, Gongliu; Song, Ningfang; Liu, Yiliang

    2016-06-22

    An inertial navigation system (INS) has been widely used in challenging GPS environments. With the rapid development of modern physics, an atomic gyroscope will come into use in the near future with a predicted accuracy of 5 × 10(-6)°/h or better. However, existing calibration methods and devices can not satisfy the accuracy requirements of future ultra-high accuracy inertial sensors. In this paper, an improved calibration model is established by introducing gyro g-sensitivity errors, accelerometer cross-coupling errors and lever arm errors. A systematic calibration method is proposed based on a 51-state Kalman filter and smoother. Simulation results show that the proposed calibration method can realize the estimation of all the parameters using a common dual-axis turntable. Laboratory and sailing tests prove that the position accuracy in a five-day inertial navigation can be improved about 8% by the proposed calibration method. The accuracy can be improved at least 20% when the position accuracy of the atomic gyro INS can reach a level of 0.1 nautical miles/5 d. Compared with the existing calibration methods, the proposed method, with more error sources and high order small error parameters calibrated for ultra-high accuracy inertial measurement units (IMUs) using common turntables, has a great application potential in future atomic gyro INSs.

  15. Status of Terra MODIS Operation, Calibration, and Performance

    NASA Technical Reports Server (NTRS)

    Xiong, X.; Wenny, B.; Wu, A.; Angal, A.; Geng, X.; Chen, H.; Dodd, J.; Link, D.; Madhavan, S.; Chen, N.; Li, Y.; Iacangelo, S.; Barnes, W.; Salomonson, V.

    2014-01-01

    Since launch in December 1999, Terra MODIS has successfully operated for nearly 15 years, making continuous observations. Data products derived from MODIS observations have significantly contributed to a wide range of studies of key geophysical parameters of the earth's eco-system of land, ocean, and atmosphere, and their changes over time. The quality of MODIS data products relies on the dedicated effort to monitor and sustain instrument health and operation, to calibrate and update sensor parameters and properties, and to improve calibration algorithms. MODIS observations are made in 36 spectral bands, covering wavelengths from visible to long-wave infrared. The reflective solar bands (1-19 and 26) are primarily calibrated by a solar diffuser (SD) panel and regularly scheduled lunar observations. The thermal emissive bands (20-25 and 27- 36) calibration is referenced to an on-board blackbody (BB) source. On-orbit changes in the sensor spectral and spatial characteristics are monitored by a spectroradiometric calibration assembly (SRCA). This paper provides an overview of Terra MODIS on-orbit operation and calibration activities and implementation strategies. It presents and summarizes sensor on-orbit performance using nearly 15 years of data from its telemetry, on-board calibrators, and lunar observations. Also discussed in this paper are changes in sensor characteristics, corrections applied to maintain MODIS level 1B (L1B) data quality, and efforts for future improvements.

  16. Novel crystal timing calibration method based on total variation

    NASA Astrophysics Data System (ADS)

    Yu, Xingjian; Isobe, Takashi; Watanabe, Mitsuo; Liu, Huafeng

    2016-11-01

    A novel crystal timing calibration method based on total variation (TV), abbreviated as ‘TV merge’, has been developed for a high-resolution positron emission tomography (PET) system. The proposed method was developed for a system with a large number of crystals, it can provide timing calibration at the crystal level. In the proposed method, the timing calibration process was formulated as a linear problem. To robustly optimize the timing resolution, a TV constraint was added to the linear equation. Moreover, to solve the computer memory problem associated with the calculation of the timing calibration factors for systems with a large number of crystals, the merge component was used for obtaining the crystal level timing calibration values. Compared with other conventional methods, the data measured from a standard cylindrical phantom filled with a radioisotope solution was sufficient for performing a high-precision crystal-level timing calibration. In this paper, both simulation and experimental studies were performed to demonstrate the effectiveness and robustness of the TV merge method. We compare the timing resolutions of a 22Na point source, which was located in the field of view (FOV) of the brain PET system, with various calibration techniques. After implementing the TV merge method, the timing resolution improved from 3.34 ns at full width at half maximum (FWHM) to 2.31 ns FWHM.

  17. Systematic Calibration for Ultra-High Accuracy Inertial Measurement Units

    PubMed Central

    Cai, Qingzhong; Yang, Gongliu; Song, Ningfang; Liu, Yiliang

    2016-01-01

    An inertial navigation system (INS) has been widely used in challenging GPS environments. With the rapid development of modern physics, an atomic gyroscope will come into use in the near future with a predicted accuracy of 5 × 10−6°/h or better. However, existing calibration methods and devices can not satisfy the accuracy requirements of future ultra-high accuracy inertial sensors. In this paper, an improved calibration model is established by introducing gyro g-sensitivity errors, accelerometer cross-coupling errors and lever arm errors. A systematic calibration method is proposed based on a 51-state Kalman filter and smoother. Simulation results show that the proposed calibration method can realize the estimation of all the parameters using a common dual-axis turntable. Laboratory and sailing tests prove that the position accuracy in a five-day inertial navigation can be improved about 8% by the proposed calibration method. The accuracy can be improved at least 20% when the position accuracy of the atomic gyro INS can reach a level of 0.1 nautical miles/5 d. Compared with the existing calibration methods, the proposed method, with more error sources and high order small error parameters calibrated for ultra-high accuracy inertial measurement units (IMUs) using common turntables, has a great application potential in future atomic gyro INSs. PMID:27338408

  18. Status of Terra MODIS operation, calibration, and performance

    NASA Astrophysics Data System (ADS)

    Xiong, Xiaoxiong J.; Wenny, Brian N.; Wu, Aisheng; Angal, Amit; Geng, Xu; Chen, Hongda; Dodd, Jennifer L.; Link, Daniel O.; Madhavan, Sriharsha; Chen, Na; Li, Yonghong; Iacangelo, Sean; Barnes, William L.; Salomonson, Vince

    2014-10-01

    Since launch in December 1999, Terra MODIS has successfully operated for nearly 15 years, making continuous observations. Data products derived from MODIS observations have significantly contributed to a wide range of studies of key geophysical parameters of the earth's eco-system of land, ocean, and atmosphere, and their changes over time. The quality of MODIS data products relies on the dedicated effort to monitor and sustain instrument health and operation, to calibrate and update sensor parameters and properties, and to improve calibration algorithms. MODIS observations are made in 36 spectral bands, covering wavelengths from visible to long-wave infrared. The reflective solar bands (1-19 and 26) are primarily calibrated by a solar diffuser (SD) panel and regularly scheduled lunar observations. The thermal emissive bands (20-25 and 27- 36) calibration is referenced to an on-board blackbody (BB) source. On-orbit changes in the sensor spectral and spatial characteristics are monitored by a spectroradiometric calibration assembly (SRCA). This paper provides an overview of Terra MODIS on-orbit operation and calibration activities and implementation strategies. It presents and summarizes sensor on-orbit performance using nearly 15 years of data from its telemetry, on-board calibrators, and lunar observations. Also discussed in this paper are changes in sensor characteristics, corrections applied to maintain MODIS level 1B (L1B) data quality, and efforts for future improvements.

  19. Kr-81m calibration factor for the npl ionisation chamber.

    PubMed

    Johansson, Lena; Stroak, Andrew

    2006-01-01

    A general method has been developed for the measurement of the activity concentration of 81mKr gas. Due to its short half-life, 13.1s, this gas has to be eluted from a 81Rb/81mKr generator. The 81Rb parent has a half-life of about 4.6 h. The calibration was done in two steps: firstly, a gamma-ray spectrometer was calibrated using 51Cr and 139Ce sources, nuclides with gamma-ray energies bracketing that of 81mKr (190.5 keV). The measurement geometry was equivalent to that of the 81mKr measurement; the sources were inserted into two collimated PTFE tubes in front of the gamma-ray detector. Secondly, a calibration factor for the NPL radionuclide calibrator was determined with a specially designed ionisation chamber insert. The 81mKr gas passed in front of the gamma-ray detector in PTFE tubing before and after entering the ionisation chamber. The calibration factor for 81mKr in the radionuclide calibrator with this geometry was independent of the gas flow rate within determined limits. The analytical calculations of the activity determination, uncertainties and measurement criteria are discussed.

  20. Calibration Techniques of the XENON1T Dark Matter Detector

    NASA Astrophysics Data System (ADS)

    Pienaar, Jacques; Xenon Collaboration

    2016-03-01

    The XENON1T experiment will probe new parameter spaces in direct dark matter searches. The successful operation of such a detector requires several calibration techniques to accurately reconstruct the position and energies of events within the active volume. 220Rn is introduced into the detector itself, through re-circulation of gaseous Xe, for use as an internal calibration sources. The decay of 220Rn and its daughters provides both high-energy alpha particles as well as a low-energy beta spectrum that can be used to calibrate the detector. Mono-energetic 2.5 MeV neutrons, allow for the in-situ calibration of the charge yield of nuclear recoil events within the detector, using double scatter events to reconstruct the deposited energy at the first scatter. Accurately positioned external Compton sources allow to determine the performance of fiducialization, as well as an insitu calibration of the charge yield of electronic recoils. This talk will present the calibration systems of the XENON1T detector.

  1. A new image calibration technique for colposcopic images

    NASA Astrophysics Data System (ADS)

    Li, Wenjing; Soto-Thompson, Marcelo; Xiong, Yizhi; Lange, Holger

    2006-03-01

    Colposcopy is a primary diagnostic method used to detect cancer and precancerous lesions of the uterine cervix. During the examination, the metaplastic and abnormal tissues exhibit different degrees of whiteness (acetowhitening effect) after applying a 3%-5% acetic acid solution. Colposcopists evaluate the color and density of the acetowhite tissue to assess the severity of lesions for the purpose of diagnosis, telemedicine, and annotation. However, the color and illumination of the colposcopic images vary with the light sources, the instruments and camera settings, as well as the clinical environments. This makes assessment of the color information very challenging even for an expert. In terms of developing a Computer-Aided Diagnosis (CAD) system for colposcopy, these variations affect the performance of the feature extraction algorithm for the acetowhite color. Non-uniform illumination from the light source is also an obstacle for detecting acetowhite regions, lesion margins and anatomic features. Therefore, in digital colposcopy, it is critical to map the color appearance of the images taken with different colposcopes into one standard color space with normalized illumination. This paper presents a novel image calibration technique for colposcopic images. First, a specially designed calibration unit is mounted on the colposcope to acquire daily calibration data prior to performing patient examinations. The calibration routine is fast, automated, accurate and reliable. We then use our illumination correction algorithm and a color calibration algorithm to calibrate the patient data. In this paper we describe these techniques and demonstrate their applications in clinical studies.

  2. A new image calibration system in digital colposcopy

    NASA Astrophysics Data System (ADS)

    Li, Wenjing; Soto-Thompson, Marcelo; Gustafsson, Ulf

    2006-12-01

    Colposcopy is a primary diagnostic method used to detect cancer and precancerous lesions of the uterine cervix. During the examination, the metaplastic and abnormal tissues exhibit different degrees of whiteness (acetowhitening effect) after applying a 3%-5% acetic acid solution. Colposcopists evaluate the color and density of the acetowhite tissue to assess the severity of lesions for the purpose of diagnosis, telemedicine, and annotation. However, the color and illumination of the colposcopic images vary with the light sources, the instruments and camera settings, as well as the clinical environments. This makes assessment of the color information very challenging even for an expert. In terms of developing a Computer-Aided Diagnosis (CAD) system for colposcopy, these variations affect the performance of the feature extraction algorithm for the acetowhite color. Non-uniform illumination from the light source is also an obstacle for detecting acetowhite regions, lesion margins, and anatomic features. There fore, in digital colposcopy, it is critical to map the color appearance of the images taken with different colposcopes into one standard color space with normalized illumination. This paper presents a novel image calibration technique for colposcopic images. First, a specially designed calibration unit is mounted on the colposcope to acquire daily calibration data prior to performing subject examinations. The calibration routine is fast, automated, accurate and reliable. We then use our illumination correction algorithm and a color calibration algorithm to calibrate the exam data. In this paper we describe these techniques and demonstrate their applications in clinical studies.

  3. Mercury Continuous Emmission Monitor Calibration

    SciTech Connect

    John Schabron; Eric Kalberer; Ryan Boysen; William Schuster; Joseph Rovani

    2009-03-12

    Mercury continuous emissions monitoring systems (CEMs) are being implemented in over 800 coal-fired power plant stacks throughput the U.S. Western Research Institute (WRI) is working closely with the Electric Power Research Institute (EPRI), the National Institute of Standards and Technology (NIST), and the Environmental Protection Agency (EPA) to facilitate the development of the experimental criteria for a NIST traceability protocol for dynamic elemental mercury vapor calibrators/generators. These devices are used to calibrate mercury CEMs at power plant sites. The Clean Air Mercury Rule (CAMR) which was published in the Federal Register on May 18, 2005 and vacated by a Federal appeals court in early 2008 required that calibration be performed with NIST-traceable standards. Despite the vacature, mercury emissions regulations in the future will require NIST traceable calibration standards, and EPA does not want to interrupt the effort towards developing NIST traceability protocols. The traceability procedures will be defined by EPA. An initial draft traceability protocol was issued by EPA in May 2007 for comment. In August 2007, EPA issued a conceptual interim traceability protocol for elemental mercury calibrators. The protocol is based on the actual analysis of the output of each calibration unit at several concentration levels ranging initially from about 2-40 {micro}g/m{sup 3} elemental mercury, and in the future down to 0.2 {micro}g/m{sup 3}, and this analysis will be directly traceable to analyses by NIST. The EPA traceability protocol document is divided into two separate sections. The first deals with the qualification of calibrator models by the vendors for use in mercury CEM calibration. The second describes the procedure that the vendors must use to certify the calibrators that meet the qualification specifications. The NIST traceable certification is performance based, traceable to analysis using isotope dilution inductively coupled plasma

  4. Calibration Adjustments to the MODIS Aqua Ocean Color Bands

    NASA Technical Reports Server (NTRS)

    Meister, Gerhard

    2012-01-01

    After the end of the SeaWiFS mission in 2010 and the MERIS mission in 2012, the ocean color products of the MODIS on Aqua are the only remaining source to continue the ocean color climate data record until the VIIRS ocean color products become operational (expected for summer 2013). The MODIS on Aqua is well beyond its expected lifetime, and the calibration accuracy of the short wavelengths (412nm and 443nm) has deteriorated in recent years_ Initially, SeaWiFS data were used to improve the MODIS Aqua calibration, but this solution was not applicable after the end of the SeaWiFS mission_ In 2012, a new calibration methodology was applied by the MODIS calibration and support team using desert sites to improve the degradation trending_ This presentation presents further improvements to this new approach. The 2012 reprocessing of the MODIS Aqua ocean color products is based on the new methodology.

  5. Quantifying the calibration uncertainty attributable to thermocouple inhomogeneity

    NASA Astrophysics Data System (ADS)

    Hill, K. D.; Gee, D. J.

    2013-09-01

    Inhomogeneity in the Seebeck coefficient as a function of position along a thermocouple wire frequently dominates the uncertainty budgets of thermocouple calibration and use. The calibration process itself, simply through exposure to elevated temperatures for relatively modest times, generates both reversible and irreversible changes to the thermocouple that are a complex function of time, temperature, alloy composition, sheath structure, etc. We present data acquired using a salt bath at 250 °C to provide the step-function-like gradient that is our spatial probe of thermoelectric homogeneity. We show how the finite width of the step-function limits our ability to assess the "true" inhomogeneity of the thermocouple, and explore how the inhomogeneity impacts the calibration uncertainty attainable with the various thermal sources used for the calibration of thermocouples (based on their characteristic temperature gradients).

  6. Calibration of solar cells' photoelectric properties and related uncertainty analysis

    NASA Astrophysics Data System (ADS)

    Meng, Haifeng; Xiong, Limin; He, Yingwei; Zhang, Junchao; Tian, Wei; Liu, Dingpu; Zhang, Jieyu; Xie, Linlin; Lei, Liu

    2014-07-01

    Solar cells' photoelectric properties calibration, i.e., current-voltage (I-V) characteristics is critical for both fundamental research and photovoltaic production line. This paper will present calibration of solar cells' I-V characteristics by a substitution method under simulate light source. Considering the calibration uncertainty and measurement accuracy, reliable measurement procedures developed in NIM with uncertainty analysis are also demonstrated. By controlling the influencing factors, relative expended combined uncertainty (Urel) of 2.1% (Isc), 1.0% (Voc) and 3.1% (Pmax) was concluded here, with a coverage factor k = 2. The measurement system meets all requirements of IEC 60904-1 and IEC 60904-9, and it has been applied to amounts of solar cells' I-V curves calibration for research institutes as well as industrial plants, which solved the problem of domestic metrology technology shortage in photovoltaic field.

  7. NVLAP activities at Department of Defense calibration laboratories

    SciTech Connect

    Schaeffer, D.M.

    1993-12-31

    There are 367 active radiological instrument calibration laboratories within the U.S. Department of Defense (DoD). Each of the four services in DoD manages, operates, and certifies the technical proficiency and competency of those laboratories under their cognizance. Each service has designated secondary calibration laboratories to trace all calibration source standards to the National Institute of Standards and Technology. Individual service radiological calibration programs and capabilities, present and future, are described, as well as the measurement quality assurance (MQA) processes for their traceability. National Voluntary Laboratory Accreditation Program (NVLAP) programs for dosimetry systems are briefly summarized. Planned NVLAP accreditation of secondary laboratories is discussed in the context of current technical challenges and future efforts.

  8. HST WFC3/IR Calibration Updates

    NASA Astrophysics Data System (ADS)

    Durbin, Meredith; Brammer, Gabriel; Long, Knox S.; Pirzkal, Norbert; Ryan, Russell E.; McCullough, Peter R.; Baggett, Sylvia M.; Gosmeyer, Catherine; Bourque, Matthew; HST WFC3 Team

    2016-01-01

    We report on several improvements to the characterization, monitoring, and calibration of the HST WFC3/IR detector. The detector performance has remained overall stable since its installation during HST Servicing Mission 4 in 2009. We present an updated persistence model that takes into account effects of exposure time and spatial variations in persistence across the detector, new grism wavelength solutions and master sky images, and a new SPARS sample sequence. We also discuss the stability of the IR gain, the time evolution and photometric properties of IR "snowballs," and the effect of IR "blobs" on point-source photometry.

  9. Imaging plates calibration to X-rays

    NASA Astrophysics Data System (ADS)

    Curcio, A.; Andreoli, P.; Cipriani, M.; Claps, G.; Consoli, F.; Cristofari, G.; De Angelis, R.; Giulietti, D.; Ingenito, F.; Pacella, D.

    2016-05-01

    The growing interest for the Imaging Plates, due to their high sensitivity range and versatility, has induced, in the last years, to detailed characterizations of their response function in different energy ranges and kind of radiation/particles. A calibration of the Imaging Plates BAS-MS, BAS-SR, BAS-TR has been performed at the ENEA-Frascati labs by exploiting the X-ray fluorescence of different targets (Ca, Cu, Pb, Mo, I, Ta) and the radioactivity of a BaCs source, in order to cover the X-ray range between few keV to 80 keV.

  10. ODERACS 2 White Spheres Optical Calibration Report

    NASA Technical Reports Server (NTRS)

    Culp, Robert D.; Gravseth, Ian; Gloor, Jason; Wantuch, Todd

    1995-01-01

    This report documents the status of the Orbital Debris Radar Calibration Spheres (ODERACS) 2 white spheres optical calibration study. The purpose of this study is to determine the spectral reflectivity and scattering characteristics in the visible wavelength region for the white spheres that were added to the project in the fall, 1994. Laboratory measurements were performed upon these objects and an analysis of the resulting data was conducted. These measurements are performed by illuminating the objects with a collimated beam of light and measuring the reflected light versus the phase angle. The phase angle is defined as the angle between the light source and the sensor, as viewed from the object. By measuring the reflected signal at the various phase angles, one is able to estimate the reflectance properties of the object. The methodology used in taking the measurements and reducing the data are presented. The results of this study will be used to support the calibration of ground-based optical instruments used in support of space debris research. Visible measurements will be made by the GEODDS, NASA and ILADOT telescopes.

  11. Swift/BAT Calibration and Spectral Response

    NASA Technical Reports Server (NTRS)

    Parsons, A.

    2004-01-01

    The Burst Alert Telescope (BAT) aboard NASA#s Swift Gamma-Ray Burst Explorer is a large coded aperture gamma-ray telescope consisting of a 2.4 m (8#) x 1.2 m (4#) coded aperture mask supported 1 meter above a 5200 square cm area detector plane containing 32,768 individual 4 mm x 4 mm x 2 mm CZT detectors. The BAT is now completely assembled and integrated with the Swift spacecraft in anticipation of an October 2004 launch. Extensive ground calibration measurements using a variety of radioactive sources have resulted in a moderately high fidelity model for the BAT spectral and photometric response. This paper describes these ground calibration measurements as well as related computer simulations used to study the efficiency and individual detector properties of the BAT detector array. The creation of a single spectral response model representative of the fully integrated BAT posed an interesting challenge and is at the heart of the public analysis tool #batdrmgen# which computes a response matrix for any given sky position within the BAT FOV. This paper will describe the batdrmgen response generator tool and conclude with a description of the on-orbit calibration plans as well as plans for the future improvements needed to produce the more detailed spectral response model that is required for the construction of an all-sky hard x-ray survey.

  12. Calibration of High Frequency MEMS Microphones

    NASA Technical Reports Server (NTRS)

    Shams, Qamar A.; Humphreys, William M.; Bartram, Scott M.; Zuckewar, Allan J.

    2007-01-01

    calibrate these microphones at frequencies up to 80 kHz. The technique relied on the use of a random, ultrasonic broadband centrifugal sound source located in a small anechoic chamber. Phase calibrations of the MEMS microphones were derived from cross spectral phase comparisons between the reference and test substitution microphones and an adjacent and invariant grazing-incidence 1/8-inch standard microphone.

  13. Mathematical calibration of Ge detectors, and the instruments that use them

    SciTech Connect

    Bronson, F.L.; Young, B.

    1997-11-01

    Efficiency calibrations for Ge detectors are typically done with the use of multiple energy calibrations sources which are added to a bulk matrix intended to simulate the measurement sample, and then deposited in the sample container. This is rather easy for common laboratory samples. Bu, even there, for many environmental samples, waste assay samples, and operational health physics samples, accurate calibrations are difficult. For these situations, various mathematical corrections or direct calibration techniques are used at Canberra. EML has pioneered the use of mathematical calibrations following source-based detector characterization measurements for in situ measurements of environmental fallout. Canberra has expanded this by the use of MCNP for the source measurements required in EML. For other calibration situations, MCNP was used directly, as the primary calibration method. This is demonstrated to be at least as accurate as source based measurements, and probably better. Recently, a new method [ISOCS] has been developed and is nearing completion. This promises to be an easy to use calibration software that can be used by the customer for in situ gamma spectroscopy to accurately measure many large sized samples, such as boxes, drums, pipes, or to calibrate small laboratory-type samples. 8 refs., 8 figs., 5 tabs.

  14. The Flux Calibration of Gaia

    NASA Astrophysics Data System (ADS)

    Pancino, E.

    2016-05-01

    The Gaia mission is described, along with its scientific potential and its updated science perfomances. Although it is often described as a self-calibrated mission, Gaia still needs to tie part of its measurements to external scales (or to convert them in physical units). A detailed decription of the Gaia spectro-photometric standard stars survey is provided, along with a short description of the Gaia calibration model. The model requires a grid of approximately 200 stars, calibrated to a few percent with respect to Vega, and covering different spectral types.

  15. Facility calibration unit of Hobby Eberly Telescope wide field upgrade

    NASA Astrophysics Data System (ADS)

    Lee, Hanshin; Hill, Gary J.; Vattiat, Brian L.; Smith, Michael P.; Haeuser, Marco

    2012-09-01

    The Hobby-Eberly Telescope (HET) Wide-Field Upgrade (WFU) will be equipped with new Facility Calibration Unit (FCU). The FCU is in support of VIRUS and the facility instruments and consists of the head and source box. The FCU head, connected to the source box through two liquid light guides, is attached to the bottom of the WFU Wide-Field Corrector (WFC) and can be deployed into the beam to inject calibration light through the WFC whenever calibration is needed. A set of Fresnel lenses is used in the FCU head to mimic the caustics of M1 as much as possible to re-produce the telescope’s focal plane illumination pattern. Various imaging/non-imaging optical components (e.g. Compound Parabolic Concentrators, cone reflectors, condenser lenses) are used for efficient coupling between different types of calibration lamps and light guides, covering wavelengths from 350nm to 1800nm. In addition, we developed an efficient and tunable Light-Emitting Diode (LED) based source and coupler for UV and Visible spectral flat field calibration. This paper presents the designs, prototypes, and as-built components / subsystems of the FCU.

  16. Gemini Planet Imager observational calibrations XI: pipeline improvements and enhanced calibrations after two years on sky

    NASA Astrophysics Data System (ADS)

    Perrin, Marshall D.; Ingraham, Patrick; Follette, Katherine B.; Maire, Jérôme; Wang, Jason J.; Savransky, Dmitry; Arriaga, Pauline; Bailey, Vanessa P.; Bruzzone, Sebastian; Chilcote, Jeffrey K.; De Rosa, Robert J.; Draper, Zachary H.; Fitzgerald, Michael P.; Greenbaum, Alexandra Z.; Hung, Li-Wei; Konopacky, Quinn; Macintosh, Bruce; Marchis, Franck; Marois, Christian; Millar-Blanchaer, Maxwell A.; Nielsen, Eric; Rajan, Abhijith; Rameau, Julien; Rantakyro, Fredrik T.; Ruffio, Jean-Baptiste; Ward-Duong, Kimberly; Wolff, Schuyler G.; Zalesky, Joseph

    2016-08-01

    The Gemini Planet Imager has been successfully obtaining images and spectra of exoplanets, brown dwarfs, and debris and protoplanetary circumstellar disks using its integral field spectrograph and polarimeter. GPI observations are transformed from raw data into high-quality astrometrically and photometrically calibrated datacubes using the GPI Data Reduction Pipeline, an open-source software framework continuously developed by our team and available to the community. It uses a flexible system of reduction recipes composed of individual primitive steps, allowing substantial customization of processing depending upon science goals. This paper provides a broad overview of the GPI pipeline, summarizes key lessons learned, and describes improved calibration methods and new capabilities available in the latest version. Enhanced automation better supports observations at the telescope with streamlined and rapid data processing, for instance through real-time assessments of contrast performance and more automated calibration file processing. We have also incorporated the GPI Data Reduction Pipeline as one component in a larger automated data system to support the GPI Exoplanet Survey campaign, while retaining its flexibility and stand-alone capabilities to support the broader GPI observer community. Several accompanying papers describe in more detail specific aspects of the calibration of GPI data in both spectral and polarimetric modes.

  17. Calibration aspects of the JEM-EUSO mission

    NASA Astrophysics Data System (ADS)

    Adams, J. H.; Ahmad, S.; Albert, J.-N.; Allard, D.; Anchordoqui, L.; Andreev, V.; Anzalone, A.; Arai, Y.; Asano, K.; Ave Pernas, M.; Baragatti, P.; Barrillon, P.; Batsch, T.; Bayer, J.; Bechini, R.; Belenguer, T.; Bellotti, R.; Belov, K.; Berlind, A. A.; Bertaina, M.; Biermann, P. L.; Biktemerova, S.; Blaksley, C.; Blanc, N.; Błȩcki, J.; Blin-Bondil, S.; Blümer, J.; Bobik, P.; Bogomilov, M.; Bonamente, M.; Briggs, M. S.; Briz, S.; Bruno, A.; Cafagna, F.; Campana, D.; Capdevielle, J.-N.; Caruso, R.; Casolino, M.; Cassardo, C.; Castellinic, G.; Catalano, C.; Catalano, G.; Cellino, A.; Chikawa, M.; Christl, M. J.; Cline, D.; Connaughton, V.; Conti, L.; Cordero, G.; Crawford, H. J.; Cremonini, R.; Csorna, S.; Dagoret-Campagne, S.; de Castro, A. J.; De Donato, C.; de la Taille, C.; De Santis, C.; del Peral, L.; Dell'Oro, A.; De Simone, N.; Di Martino, M.; Distratis, G.; Dulucq, F.; Dupieux, M.; Ebersoldt, A.; Ebisuzaki, T.; Engel, R.; Falk, S.; Fang, K.; Fenu, F.; Fernández-Gómez, I.; Ferrarese, S.; Finco, D.; Flamini, M.; Fornaro, C.; Franceschi, A.; Fujimoto, J.; Fukushima, M.; Galeotti, P.; Garipov, G.; Geary, J.; Gelmini, G.; Giraudo, G.; Gonchar, M.; González Alvarado, C.; Gorodetzky, P.; Guarino, F.; Guzmán, A.; Hachisu, Y.; Harlov, B.; Haungs, A.; Hernández Carretero, J.; Higashide, K.; Ikeda, D.; Ikeda, H.; Inoue, N.; Inoue, S.; Insolia, A.; Isgrò, F.; Itow, Y.; Joven, E.; Judd, E. G.; Jung, A.; Kajino, F.; Kajino, T.; Kaneko, I.; Karadzhov, Y.; Karczmarczyk, J.; Karus, M.; Katahira, K.; Kawai, K.; Kawasaki, Y.; Keilhauer, B.; Khrenov, B. A.; Kim, J.-S.; Kim, S.-W.; Kim, S.-W.; Kleifges, M.; Klimov, P. A.; Kolev, D.; Kreykenbohm, I.; Kudela, K.; Kurihara, Y.; Kusenko, A.; Kuznetsov, E.; Lacombe, M.; Lachaud, C.; Lee, J.; Licandro, J.; Lim, H.; López, F.; Maccarone, M. C.; Mannheim, K.; Maravilla, D.; Marcelli, L.; Marini, A.; Martinez, O.; Masciantonio, G.; Mase, K.; Matev, R.; Medina-Tanco, G.; Mernik, T.; Miyamoto, H.; Miyazaki, Y.; Mizumoto, Y.; Modestino, G.; Monaco, A.; Monnier-Ragaigne, D.; Morales de los Ríos, J. A.; Moretto, C.; Morozenko, V. S.; Mot, B.; Murakami, T.; Murakami, M. Nagano; Nagata, M.; Nagataki, S.; Nakamura, T.; Napolitano, T.; Naumov, D.; Nava, R.; Neronov, A.; Nomoto, K.; Nonaka, T.; Ogawa, T.; Ogio, S.; Ohmori, H.; Olinto, A. V.; Orleański, P.; Osteria, G.; Panasyuk, M. I.; Parizot, E.; Park, I. H.; Park, H. W.; Pastircak, B.; Patzak, T.; Paul, T.; Pennypacker, C.; Perez Cano, S.; Peter, T.; Picozza, P.; Pierog, T.; Piotrowski, L. W.; Piraino, S.; Plebaniak, Z.; Pollini, A.; Prat, P.; Prévôt, G.; Prieto, H.; Putis, M.; Reardon, P.; Reyes, M.; Ricci, M.; Rodríguez, I.; Rodríguez Frías, M. D.; Ronga, F.; Roth, M.; Rothkaehl, H.; Roudil, G.; Rusinov, I.; Rybczyński, M.; Sabau, M. D.; Sáez-Cano, G.; Sagawa, H.; Saito, A.; Sakaki, N.; Sakata, M.; Salazar, H.; Sánchez, S.; Santangelo, A.; Santiago Crúz, L.; Sanz Palomino, M.; Saprykin, O.; Sarazin, F.; Sato, H.; Sato, M.; Schanz, T.; Schieler, H.; Scotti, V.; Segreto, A.; Selmane, S.; Semikoz, D.; Serra, M.; Sharakin, S.; Shibata, T.; Shimizu, H. M.; Shinozaki, K.; Shirahama, T.; Siemieniec-Oziȩbło, G.; Silva López, H. H.; Sledd, J.; Słomińska, K.; Sobey, A.; Sugiyama, T.; Supanitsky, D.; Suzuki, M.; Szabelska, B.; Szabelski, J.; Tajima, F.; Tajima, N.; Tajima, T.; Takahashi, Y.; Takami, H.; Takeda, M.; Takizawa, Y.; Tenzer, C.; Tibolla, O.; Tkachev, L.; Tokuno, H.; Tomida, T.; Tone, N.; Toscano, S.; Trillaud, F.; Tsenov, R.; Tsunesada, Y.; Tsuno, K.; Tymieniecka, T.; Uchihori, Y.; Unger, M.; Vaduvescu, O.; Valdés-Galicia, J. F.; Vallania, P.; Valore, L.; Vankova, G.; Vigorito, C.; Villaseñor, L.; von Ballmoos, P.; Wada, S.; Watanabe, J.; Watanabe, S.; Watts, J.; Weber, M.; Weiler, T. J.; Wibig, T.; Wiencke, L.; Wille, M.; Wilms, J.; Włodarczyk, Z.; Yamamoto, T.; Yamamoto, Y.; Yang, J.; Yano, H.; Yashin, I. V.; Yonetoku, D.; Yoshida, K.; Yoshida, S.; Young, R.; Zotov, M. Yu.; Zuccaro Marchi, A.

    2015-11-01

    The JEM-EUSO telescope will be, after calibration, a very accurate instrument which yields the number of received photons from the number of measured photo-electrons. The project is in phase A (demonstration of the concept) including already operating prototype instruments, i.e. many parts of the instrument have been constructed and tested. Calibration is a crucial part of the instrument and its use. The focal surface (FS) of the JEM-EUSO telescope will consist of about 5000 photo-multiplier tubes (PMTs), which have to be well calibrated to reach the required accuracy in reconstructing the air-shower parameters. The optics system consists of 3 plastic Fresnel (double-sided) lenses of 2.5 m diameter. The aim of the calibration system is to measure the efficiencies (transmittances) of the optics and absolute efficiencies of the entire focal surface detector. The system consists of 3 main components: (i) Pre-flight calibration devices on ground, where the efficiency and gain of the PMTs will be measured absolutely and also the transmittance of the optics will be. (ii) On-board relative calibration system applying two methods: a) operating during the day when the JEM-EUSO lid will be closed with small light sources on board. b) operating during the night, together with data taking: the monitoring of the background rate over identical sites. (iii) Absolute in-flight calibration, again, applying two methods: a) measurement of the moon light, reflected on high altitude, high albedo clouds. b) measurements of calibrated flashes and tracks produced by the Global Light System (GLS). Some details of each calibration method will be described in this paper.

  18. Preflight and in-flight calibration plan for ASTER

    USGS Publications Warehouse

    Ono, A.; Sakuma, F.; Arai, K.; Yamaguchi, Y.; Fujisada, H.; Slater, P.N.; Thome, K.J.; Palluconi, Frank Don; Kieffer, H.H.

    1996-01-01

    Preflight and in-flight radiometric calibration plans are described for the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) that is a multispectral optical imager of high spatial resolution. It is designed for the remote sensing from orbit of land surfaces and clouds, and is expected to be launched in 1998 on NASA's EOS AM-1 spacecraft. ASTER acquires images in three separate spectral regions, the visible and near-infrared (VNIR), the shortwave infrared (SWIR), and the thermal infrared (TIR) with three imaging radiometer subsystems. The absolute radiometric accuracy is required to be better than 4% for VNIR and SWIR radiance measurements and 1 to 3 K, depending on the temperature regions from 200 to 370 K, for TIR temperature measurements. A reference beam is introduced at the entrance pupil of each imaging radiometer to provide the in-flight calibration Thus, the ASTER instrument includes internal onboard calibration units that comprise incandescent lamps for the VNIR and SWIR and a blackbody radiator for the TIR as reference sources. The calibration reliability of the VNIR and SWIR is enhanced by a dual system of onboard calibration units as well as by high-stability halogen lamps. A ground calibration system of spectral radiances traceable to fixed-point blackbodies is used for the preflight VNIR and SWIR calibration. Because of the possibility of nonuniform contamination effects on the partial-aperture onboard calibration, it is desirable to check their results with respect to other methods. Reflectance- and radiance-based vicarious methods have been developed for this purpose. These, and methods involving in-flight cross-calibration with other sensors are also described.

  19. Variable Acceleration Force Calibration System (VACS)

    NASA Technical Reports Server (NTRS)

    Rhew, Ray D.; Parker, Peter A.; Johnson, Thomas H.; Landman, Drew

    2014-01-01

    Conventionally, force balances have been calibrated manually, using a complex system of free hanging precision weights, bell cranks, and/or other mechanical components. Conventional methods may provide sufficient accuracy in some instances, but are often quite complex and labor-intensive, requiring three to four man-weeks to complete each full calibration. To ensure accuracy, gravity-based loading is typically utilized. However, this often causes difficulty when applying loads in three simultaneous, orthogonal axes. A complex system of levers, cranks, and cables must be used, introducing increased sources of systematic error, and significantly increasing the time and labor intensity required to complete the calibration. One aspect of the VACS is a method wherein the mass utilized for calibration is held constant, and the acceleration is changed to thereby generate relatively large forces with relatively small test masses. Multiple forces can be applied to a force balance without changing the test mass, and dynamic forces can be applied by rotation or oscillating acceleration. If rotational motion is utilized, a mass is rigidly attached to a force balance, and the mass is exposed to a rotational field. A large force can be applied by utilizing a large rotational velocity. A centrifuge or rotating table can be used to create the rotational field, and fixtures can be utilized to position the force balance. The acceleration may also be linear. For example, a table that moves linearly and accelerates in a sinusoidal manner may also be utilized. The test mass does not have to move in a path that is parallel to the ground, and no re-leveling is therefore required. Balance deflection corrections may be applied passively by monitoring the orientation of the force balance with a three-axis accelerometer package. Deflections are measured during each test run, and adjustments with respect to the true applied load can be made during the post-processing stage. This paper will

  20. Calibration and deployment of a new NIST transfer radiometer for broadband and spectral calibration of space chambers (MDXR)

    NASA Astrophysics Data System (ADS)

    Jung, Timothy M.; Carter, Adriaan C.; Woods, Solomon I.; Kaplan, Simon G.

    2011-06-01

    The Low-Background Infrared (LBIR) facility at NIST has performed on-site calibration and initial off-site deployments of a new infrared transfer radiometer with an integrated cryogenic Fourier transform spectrometer (Cryo- FTS). This mobile radiometer can be deployed to customer sites for broadband and spectral calibrations of space chambers and low-background hardware-in-the-loop testbeds. The Missile Defense Transfer Radiometer (MDXR) has many of the capabilities of a complete IR calibration facility and replaces our existing filter-based transfer radiometer (BXR) as the NIST standard detector deployed to customer facilities. The MDXR features numerous improvements over the BXR, including: a cryogenic Fourier transform spectrometer, an on-board absolute cryogenic radiometer (ACR) and an internal blackbody reference source with an integrated collimator. The Cryo-FTS can be used to measure high resolution spectra from 3 to 28 micrometers, using a Si:As blocked-impurity-band (BIB) detector. The on-board ACR can be used for self-calibration of the MDXR BIB as well as for absolute measurements of external infrared sources. A set of filter wheels and a rotating polarizer within the MDXR allow for filter-based and polarization-sensitive measurements. The optical design of the MDXR makes both radiance and irradiance measurements possible and enables calibration of both divergent and collimated sources. Results of on-site calibration of the MDXR using its internal blackbody source and an external reference source will be discussed, as well as the performance of the new radiometer in its initial deployments to customer sites.

  1. Artifact correction and absolute radiometric calibration techniques employed in the Landsat 7 image assessment system

    USGS Publications Warehouse

    Boncyk, Wayne C.; Markham, Brian L.; Barker, John L.; Helder, Dennis

    1996-01-01

    The Landsat-7 Image Assessment System (IAS), part of the Landsat-7 Ground System, will calibrate and evaluate the radiometric and geometric performance of the Enhanced Thematic Mapper Plus (ETM +) instrument. The IAS incorporates new instrument radiometric artifact correction and absolute radiometric calibration techniques which overcome some limitations to calibration accuracy inherent in historical calibration methods. Knowledge of ETM + instrument characteristics gleaned from analysis of archival Thematic Mapper in-flight data and from ETM + prelaunch tests allow the determination and quantification of the sources of instrument artifacts. This a priori knowledge will be utilized in IAS algorithms designed to minimize the effects of the noise sources before calibration, in both ETM + image and calibration data.

  2. Fixture For Calibrating Pressure Probe

    NASA Technical Reports Server (NTRS)

    Ashby, George C., Jr.; Vasquez, Peter; Horsley, Lewis A.; Bowman, John T.; Zumbrun, Henry N.; Eves, John W.

    1994-01-01

    Fixture in form of specially designed clamshell housing enables in situ calibration of pressure transducer mounted in body of pressure probe in wind tunnel. Includes two metal half shells machined with necks and matching cavities, when put together, define larger neck and cavity accommodating probe. Probe secured to bottom half shell by use of clamp before installing top half shell: necessary to follow sequence to protect probe during assembly. Clamshell calibration fixture attached to pressure probe in few minutes, making it possible to calibrate pressure transducer at convenient times. Calibrations performed before and after wind-tunnel runs each day, between runs in event of delays or suspected malfunctions, and essentially any other time, without having to remove probe from wind tunnel.

  3. 40 CFR 1065.310 - Torque calibration.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... range. Oscillate or rotate the dynamometer during calibration to reduce frictional static hysteresis... during calibration to reduce frictional static hysteresis. In this case, the reference torque...

  4. 40 CFR 1065.310 - Torque calibration.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... range. Oscillate or rotate the dynamometer during calibration to reduce frictional static hysteresis... during calibration to reduce frictional static hysteresis. In this case, the reference torque...

  5. Rotary mode system initial instrument calibration

    SciTech Connect

    Johns, B.R.

    1994-10-01

    The attached report contains the vendor calibration procedures used for the initial instrument calibration of the rotary core sampling equipment. The procedures are from approved vendor information files.

  6. Nuclear Recoil Calibration of DarkSide-50

    NASA Astrophysics Data System (ADS)

    Edkins, Erin; DarkSide Collaboration

    2016-03-01

    DarkSide-50 dark matter experiment is a liquid argon time projection chamber (TPC) surrounded by a liquid scintillator active neutron veto, designed for the direct detection of Weakly Interacting Massive Particles (WIMPs). The success of such an experiment is dependent upon a detailed understanding of both the expected signal and backgrounds, achieved using radioactive calibration sources of known energies. Nuclear recoils provide a measurement of both the expected signal and the most dangerous background, as nuclear recoils from neutrons cannot be distinguished from a dark matter signal on an event-by-event basis in the TPC. In this talk, I will present the DS-50 calibration system, and analysis of the results of the calibration of DarkSide-50 to nuclear recoils using radioactive neutron sources. See also the DS-50 presentations by X. Xiang and G. Koh.

  7. Practical Study of Psychrometer Calibrations

    NASA Astrophysics Data System (ADS)

    Kentved, Anders Bonde; Heinonen, Martti; Hudoklin, Domen

    2012-09-01

    Psychrometers remain the most widely used instruments for controlling the humidity in climatic test chambers, yet the calibration of these instruments is particularly challenging. Psychrometer calibrations require careful consideration of influence variables such as the fitting and cleanliness of the wick, the effect of the calibration chamber on the air flow past the sensors, on radiation incident on the sensors, and on the dissipation heat from the built-in fan (if included). In addition, uncertainty requirements for calibration of such psychrometers are typically around 1 %rh to 2 %rh, i.e., close to the best calibration and measurement uncertainties (CMCs) claimed by national metrology institutes (NMIs). As well as their role in supporting CMCs, inter-comparisons provide a good test-ground to ensure all influence variables are controlled or otherwise accounted for in the uncertainty budget. This paper presents the results of a comparison of psychrometer calibrations performed by the NMIs in Denmark, Slovenia, and Finland. The comparison was carried out under EURAMET Project No. 1033 with the aim to investigate the equivalence of psychrometer calibrations performed at the highest level and to gather practical experience to be used in similar comparisons in the future. An aspirated electro-psychrometer was used for the comparison, and calibrations were carried out in the range from 15 %rh to 93 %rh in a temperature range from 15 °C to 70 °C. While the results show good agreement at high relative humidity, significant differences at low relative humidity are reported. It is suggested that the differences are caused by a combination of psychrometer wick contamination and a difference in the wick-wetting methods used by the participant laboratories.

  8. Infrasound Sensor Calibration and Response

    DTIC Science & Technology

    2012-09-01

    functions with faster rise times. SUMMARY We have documented past work on the determination of the calibration constant of the LANL infrasound sensor...Monitoring Technologies 735 Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden for the collection of information is estimated...National Laboratory ( LANL ) has operated an infrasound sensor calibration chamber that operates over a frequency range of 0.02 to 4 Hz. This chamber has

  9. Issues in energy calibration, nonlinearity, and signal processing for gamma-ray microcalorimeter

    SciTech Connect

    Rabin, Mike W; Hoover, Andrew S; Bacrania, Mnesh K; Hoteling, Nathan; Croce, M; Karpius, P J; Ullom, J N; Bennett, D A; Horansky, R D; Vale, L R; Doriese, W B

    2009-01-01

    Issues regarding the energy calibration of high dynamic range microcalorimeter detector arrays are presented with respect to new results from a minor actinide-mixed oxide radioactive source. The need to move to larger arrays of such detectors necessitates the implementation of automated analysis procedures, which turn out to be nontrivial due to complex calibration shapes and pixel-to-pixel variability. Some possible avenues for improvement, including a more physics-based calibration procedure, are suggested.

  10. Blackbody comparator for thermocouple calibration

    SciTech Connect

    Ojanen, M.; Hahtela, O. M.; Heinonen, M.

    2013-09-11

    MIKES is developing a measurement set-up for calibrating thermocouples in the temperature range 960 °C - 1500 °C. The calibration method is based on direct comparison of thermocouples and radiation thermometers. We have designed a graphite blackbody comparator cell, which is operated in a horizontal single-zone tube furnace. The cell includes two blackbody cavities for radiation temperature measurements. The cavities have openings on opposite sides of the cell, allowing simultaneous measurement with two radiation thermometers. The design of the comparator allows three thermocouples to be calibrated simultaneously. The thermocouples to be calibrated are inserted in thermometer wells around one of the measurement cavities. We characterize the blackbody comparator in terms of repeatability, temperature distribution and emissivity. Finally, we validate the uncertainty analysis by comparing calibration results obtained for type B and S thermocouples to the calibration results reported by Technical Research Institute of Sweden (SP), and MIKES. The agreement in the temperature range 1000 °C - 1500 °C is within 0.90 °C, the average deviation being 0.17 °C.

  11. The DICE calibration project Design, characterization, and first results

    NASA Astrophysics Data System (ADS)

    Regnault, N.; Guyonnet, A.; Schahmanèche, K.; Le Guillou, L.; Antilogus, P.; Astier, P.; Barrelet, E.; Betoule, M.; Bongard, S.; Cuillandre, J.-C.; Juramy, C.; Pain, R.; Rocci, P.-F.; Tisserand, P.; Villa, F.

    2015-09-01

    Aims: We describe the design, operation, and first results of a photometric calibration project, called DICE (Direct Illumination Calibration Experiment), aiming at achieving precise instrumental calibration of optical telescopes. The heart of DICE is an illumination device composed of 24 narrow-spectrum, high-intensity, light-emitting diodes (LED) chosen to cover the ultraviolet-to-near-infrared spectral range. It implements a point-like source placed at a finite distance from the telescope entrance pupil, yielding a flat field illumination that covers the entire field of view of the imager. The purpose of this system is to perform a lightweight routine monitoring of the imager passbands with a precision better than 5 per-mil on the relative passband normalisations and about 3 Å on the filter cutoff positions. Methods: Prior to installation, the light source is calibrated on a spectrophotometric bench. As our fundamental metrology standard, we use a photodiode calibrated at the National Institute of Standards and Technology (NIST). The radiant intensity of each beam is mapped, and spectra are measured for each LED. All measurements are conducted at temperatures ranging from 0 °C to 25 °C in order to study the temperature dependence of the system. The photometric and spectroscopic measurements are combined into a model that predicts the spectral intensity of the source as a function of temperature. Results: We find that the calibration beams are stable at the 10-4 level - after taking the slight temperature dependence of the LED emission properties into account. We show that the spectral intensity of the source can be characterised with a precision of 3 Å in wavelength, depending on how accurately we are able to calibrate the wavelength response of the mononochromator. In flux, we reach an accuracy of about 0.2 - 0.5% depending on how we understand the off-diagonal terms of the error budget affecting the calibration of the NIST photodiode. We describe how with

  12. Low energy stable plasma calibration facility.

    PubMed

    Frederick-Frost, K M; Lynch, K A

    2007-07-01

    We have designed and fabricated a low energy plasma calibration facility for testing and calibration of rocket-borne charged-particle detectors and for the investigation of plasma sheath formation in an environment with ionospheric plasma energies, densities, and Debye lengths. We describe the vacuum system and associated plasma source, which was modified from a Naval Research Laboratory design [Bowles et al. Rev. Sci. Instrum. 67, 455 (1996)]. Mechanical and electrical modifications to this cylindrical microwave resonant source are outlined together with a different method of operating the magnetron that achieves a stable discharge. This facility produces unmagnetized plasmas with densities from 1x10(3)/cm(3) to 6x10(5)/cm(3), electron temperatures from 0.1 to 1.7 eV, and plasma potentials from 0.5 to 8 V depending on varying input microwave power and neutral gas flow. For the range of input microwave power explored (350-600 W), the energy density of the plasma remains constant because of an inverse relationship between density and temperature. This relationship allows a wide range of Debye lengths (0.3-8.4 cm) to be investigated, which is ideal for simulating the ionospheric plasma sheaths we explore.

  13. Landsat-8 Thermal Infrared Sensor (TIRS) Vicarious Radiometric Calibration

    NASA Technical Reports Server (NTRS)

    Barsi, Julia A.; Shott, John R.; Raqueno, Nina G.; Markham, Brian L.; Radocinski, Robert G.

    2014-01-01

    Launched in February 2013, the Landsat-8 carries on-board the Thermal Infrared Sensor (TIRS), a two-band thermal pushbroom imager, to maintain the thermal imaging capability of the Landsat program. The TIRS bands are centered at roughly 10.9 and 12 micrometers (Bands 10 and 11 respectively). They have 100 m spatial resolution and image coincidently with the Operational Land Imager (OLI), also on-board Landsat-8. The TIRS instrument has an internal calibration system consisting of a variable temperature blackbody and a special viewport with which it can see deep space; a two point calibration can be performed twice an orbit. Immediately after launch, a rigorous vicarious calibration program was started to validate the absolute calibration of the system. The two vicarious calibration teams, NASA/Jet Propulsion Laboratory (JPL) and the Rochester Institute of Technology (RIT), both make use of buoys deployed on large water bodies as the primary monitoring technique. RIT took advantage of cross-calibration opportunity soon after launch when Landsat-8 and Landsat-7 were imaging the same targets within a few minutes of each other to perform a validation of the absolute calibration. Terra MODIS is also being used for regular monitoring of the TIRS absolute calibration. The buoy initial results showed a large error in both bands, 0.29 and 0.51 W/sq m·sr·micrometers or -2.1 K and -4.4 K at 300 K in Band 10 and 11 respectively, where TIRS data was too hot. A calibration update was recommended for both bands to correct for a bias error and was implemented on 3 February 2014 in the USGS/EROS processing system, but the residual variability is still larger than desired for both bands (0.12 and 0.2 W/sq m·sr·micrometers or 0.87 and 1.67 K at 300 K). Additional work has uncovered the source of the calibration error: out-of-field stray light. While analysis continues to characterize the stray light contribution, the vicarious calibration work proceeds. The additional data have

  14. High-precision efficiency calibration of a high-purity co-axial germanium detector

    NASA Astrophysics Data System (ADS)

    Blank, B.; Souin, J.; Ascher, P.; Audirac, L.; Canchel, G.; Gerbaux, M.; Grévy, S.; Giovinazzo, J.; Guérin, H.; Nieto, T. Kurtukian; Matea, I.; Bouzomita, H.; Delahaye, P.; Grinyer, G. F.; Thomas, J. C.

    2015-03-01

    A high-purity co-axial germanium detector has been calibrated in efficiency to a precision of about 0.15% over a wide energy range. High-precision scans of the detector crystal and γ-ray source measurements have been compared to Monte-Carlo simulations to adjust the dimensions of a detector model. For this purpose, standard calibration sources and short-lived online sources have been used. The resulting efficiency calibration reaches the precision needed e.g. for branching ratio measurements of super-allowed β decays for tests of the weak-interaction standard model.

  15. DOE Radiological Calibrations Intercomparison Program: Results of fiscal year 1987

    SciTech Connect

    Cummings, F.M.; McDonald, J.C.

    1988-06-01

    This report presents the FY 1987 results of the radiological calibrations intercomparison program. The intercomparison operation is discussed, and the equipment is described, particularly the instrument set, the beta source set, and relevant calculations. Solutions to problems and improvements in the program are suggested, and conclusions are then introduced. 9 refs., 3 figs., 8 tabs.

  16. Accuracy of airspeed measurements and flight calibration procedures

    NASA Technical Reports Server (NTRS)

    Huston, Wilber B

    1948-01-01

    The sources of error that may enter into the measurement of airspeed by pitot-static methods are reviewed in detail together with methods of flight calibration of airspeed installations. Special attention is given to the problem of accurate measurements of airspeed under conditions of high speed and maneuverability required of military airplanes. (author)

  17. Atmospheric simulator and calibration system for remote sensing radiometers

    NASA Technical Reports Server (NTRS)

    Holland, J. A.

    1983-01-01

    A system for calibrating the MAPS (measurement of air pollution from satellites) instruments was developed. The design of the system provides a capability for simulating a broad range of radiant energy source temperatures and a broad range of atmospheric pressures, temperatures, and pollutant concentrations for a single slab atmosphere. The system design and the system operation are described.

  18. The detector calibration system for the CUORE cryogenic bolometer array

    NASA Astrophysics Data System (ADS)

    Cushman, Jeremy S.; Dally, Adam; Davis, Christopher J.; Ejzak, Larissa; Lenz, Daniel; Lim, Kyungeun E.; Heeger, Karsten M.; Maruyama, Reina H.; Nucciotti, Angelo; Sangiorgio, Samuele; Wise, Thomas

    2017-02-01

    The Cryogenic Underground Observatory for Rare Events (CUORE) is a ton-scale cryogenic experiment designed to search for neutrinoless double-beta decay of 130Te and other rare events. The CUORE detector consists of 988 TeO2 bolometers operated underground at 10 mK in a dilution refrigerator at the Laboratori Nazionali del Gran Sasso. Candidate events are identified through a precise measurement of their energy. The absolute energy response of the detectors is established by the regular calibration of each individual bolometer using gamma sources. The close-packed configuration of the CUORE bolometer array combined with the extensive shielding surrounding the detectors requires the placement of calibration sources within the array itself. The CUORE Detector Calibration System is designed to insert radioactive sources into and remove them from the cryostat while respecting the stringent heat load, radiopurity, and operational requirements of the experiment. This paper describes the design, commissioning, and performance of this novel source calibration deployment system for ultra-low-temperature environments.

  19. Absolute intensity calibration of the Wendelstein 7-X high efficiency extreme ultraviolet overview spectrometer system

    NASA Astrophysics Data System (ADS)

    Greiche, Albert; Biel, Wolfgang; Marchuk, Oleksandr; Burhenn, Rainer

    2008-09-01

    The new high effiency extreme ultraviolet overview spectrometer (HEXOS) system for the stellarator Wendelstein 7-X is now mounted for testing and adjustment at the tokamak experiment for technology oriented research (TEXTOR). One part of the testing phase was the intensity calibration of the two double spectrometers which in total cover a spectral range from 2.5 to 160.0 nm with overlap. This work presents the current intensity calibration curves for HEXOS and describes the method of calibration. The calibration was implemented with calibrated lines of a hollow cathode light source and the branching ratio technique. The hollow cathode light source provides calibrated lines from 16 up to 147 nm. We could extend the calibrated region in the spectrometers down to 2.8 nm by using the branching line pairs emitted by an uncalibrated pinch extreme ultraviolet light source as well as emission lines from boron and carbon in TEXTOR plasmas. In total HEXOS is calibrated from 2.8 up to 147 nm, which covers most of the observable wavelength region. The approximate density of carbon in the range of the minor radius from 18 to 35 cm in a TEXTOR plasma determined by simulating calibrated vacuum ultraviolet emission lines with a transport code was 5.5×1017 m-3 which corresponds to a local carbon concentration of 2%.

  20. FY07 Final Report for Calibration Systems

    SciTech Connect

    Myers, Tanya L.; Broocks, Bryan T.; Cannon, Bret D.; Ho, Nicolas

    2007-12-01

    -in effect appears in which the power increases over a certain time period. Repeatability better than 1%, however, is demonstrated for most of the radiance levels after this initial burn-in. In FY06, PNNL also began investigating a fiber-coupled RT QCL for a compact IR calibration source. PNNL demonstrated a uniform beam profile by measuring a time-averaged response and modulating the fiber optic with a motor to minimize the effects of speckle. In FY07, PNNL examined the power stability of fiber-coupled QCLs. Feedback appears to degrade the stability so that anti-reflective coatings for fibers may be essential. In FY07, PNNL continued to investigate the stability of room temperature QCLs as well as the measurement technique to provide a quantitative estimate for the measurement uncertainty. We designed and built a custom environmental enclosure to reduce the measurement uncertainty. After an initial burn-in, we have achieved uncertainties better than 0.1% for data collected over almost 100 hours of operation. We also built a bench-top system to demonstrate how the QC laser can be used to calibrate a microbolometer array and illustrated the importance of a multi-point calibration.

  1. Spectroradiometric calibration of the Thematic Mapper and Multispectral Scanner system

    NASA Technical Reports Server (NTRS)

    Slater, P. N.; Palmer, J. M. (Principal Investigator)

    1985-01-01

    The results of analyses of Thematic Mapper (TM) images acquired on July 8 and October 28, 1984, and of a check of the calibration of the 1.22-m integrating sphere at Santa Barbara Research Center (SBRC) are described. The results obtained from the in-flight calibration attempts disagree with the pre-flight calibrations for bands 2 and 4. Considerable effort was expended in an attempt to explain the disagreement. The difficult point to explain is that the difference between the radiances predicted by the radiative transfer code (the code radiances) and the radiances predicted by the preflight calibration (the pre-flight radiances) fluctuate with spectral band. Because the spectral quantities measured at White Sands show little change with spectral band, these fluctuations are not anticipated. Analyses of other targets at White Sands such as clouds, cloud shadows, and water surfaces tend to support the pre-flight and internal calibrator calibrations. The source of the disagreement has not been identified. It could be due to: (1) a computational error in the data reduction; (2) an incorrect assumption in the input to the radiative transfer code; or (3) incorrect operation of the field equipment.

  2. An absolute sensitivity calibration of the JET VUV SPRED spectrometer

    NASA Astrophysics Data System (ADS)

    Lawson, K. D.; Coffey, I. H.; Zacks, J.; Stamp, M. F.; contributors, JET-EFDA

    2009-04-01

    The determination of a good relative and absolute sensitivity calibration for wideband VUV spectrometers is challenging. On JET, the possible T and Be contamination of the VUV spectrometer precludes its removal to a synchrotron source and, consequently, a range of alternative in situ techniques have been investigated in depth. This has resulted in a reliable calibration for the complete spectral range, the relative calibration at short wavelengths being particularly accurate. At these wavelengths, a novel approach is used, in which the calibration is extended using a number of Na- and Li-like metal doublets. At longer wavelengths, the Li-like doublets of Ar and Ne have been used in conjunction with CII, CIII and CIV line intensity ratios. Unexplained discrepancies between the measured and modelled C results have meant that the exceptional short wavelength accuracy has not be repeated at these longer wavelengths. The absolute sensitivity has been determined from branching ratios to an absolutely calibrated visible spectrometer. The long term stability of the calibration is discussed.

  3. Calibrating echelle spectrographs with Fabry-Pérot etalons

    NASA Astrophysics Data System (ADS)

    Bauer, F. F.; Zechmeister, M.; Reiners, A.

    2015-09-01

    Context. Over the past decades hollow-cathode lamps have been calibration standards for spectroscopic measurements. Advancing to cm/s radial velocity precisions with the next generation of instruments requires more suitable calibration sources with more lines and fewer dynamic range problems. Fabry-Pérot interferometers provide a regular and dense grid of lines and homogeneous amplitudes, which makes them good candidates for next-generation calibrators. Aims: We investigate the usefulness of Fabry-Pérot etalons in wavelength calibration, present an algorithm to incorporate the etalon spectrum in the wavelength solution, and examine potential problems. Methods: The quasi-periodic pattern of Fabry-Pérot lines was used along with a hollow-cathode lamp to anchor the numerous spectral features on an absolute scale. We tested our method with the HARPS spectrograph and compared our wavelength solution to the one derived from a laser frequency comb. Results: The combined hollow-cathode lamp/etalon calibration overcomes large distortion (50 m/s) in the wavelength solution of the HARPS data reduction software. The direct comparison to the laser frequency comb shows differences of only 10 m/s at most. Conclusions: Combining hollow-cathode lamps with Fabry-Pérot interferometers can lead to substantial improvements in the wavelength calibration of echelle spectrographs. Etalons can provide economical alternatives to the laser frequency comb, especially for smaller projects.

  4. Updating the WFC3 G102 and G141 Grism Calibration

    NASA Astrophysics Data System (ADS)

    Pirzkal, Norbert; Lee, J. C.; Hilbert, B.

    2013-01-01

    We present newly derived trace and wavelength calibrations of the WFC3 IR G102 and G141 grisms and compare them to the previous set of calibrations. Past calibration efforts were based on 2010 observations. While field dependence was accounted for with the use of multiple pointings, calibration sources have since been observed as part of Cycles 17, 18 and 19 calibration proposals. New observations are taken every HST cycle to monitor for potential changes in the trace, wavelength, and flux calibrations, and these calibrations are shown to be stable to ~1% since the installation of WFC3 in 2009. Furthermore, we also show that the non-negligible field dependence of the calibrations has not changed significantly over time. These newer calibration data were also purposefully obtained using different calibration objects and using an increased number of positions on the detector. While the initial grism calibrations were based on 9 positions over the field of view, by combining all of the available data we can now derive a more finely sampled field dependence of the grism dispersion solutions.

  5. Calibration approach and plan for the sea and land surface temperature radiometer

    NASA Astrophysics Data System (ADS)

    Smith, David L.; Nightingale, Tim J.; Mortimer, Hugh; Middleton, Kevin; Edeson, Ruben; Cox, Caroline V.; Mutlow, Chris T.; Maddison, Brian J.; Coppo, Peter

    2014-01-01

    The sea and land surface temperature radiometer (SLSTR) to be flown on the European Space Agency's (ESA) Sentinel-3 mission is a multichannel scanning radiometer that will continue the 21 year dataset of the along-track scanning radiometer (ATSR) series. As its name implies, measurements from SLSTR will be used to retrieve global sea surface temperatures to an uncertainty of <0.3 K traced to international standards. To achieve, these low uncertainties require an end-to-end instrument calibration strategy that includes prelaunch calibration at subsystem and instrument level, on-board calibration systems, and sustained postlaunch activities. The authors describe the preparations for the prelaunch calibration activities, including the spectral response, the instrument level alignment tests, and the solar and infrared radiometric calibrations. A purpose built calibration rig has been designed and built at the Rutherford Appleton Laboratory space department (RAL Space) that will accommodate the SLSTR instrument, the infrared calibration sources, and the alignment equipment. The calibration rig has been commissioned and results of these tests will be presented. Finally, the authors will present the planning for the on-orbit monitoring and calibration activities to ensure that the calibration is maintained. These activities include vicarious calibration techniques that have been developed through previous missions and the deployment of ship-borne radiometers.

  6. Research on the calibration of ultraviolet energy meters

    NASA Astrophysics Data System (ADS)

    Lin, Fangsheng; Yin, Dejin; Li, Tiecheng; Lai, Lei; Xia, Ming

    2016-10-01

    Ultraviolet (UV) radiation is a kind of non-lighting radiation with the wavelength range from 100nm to 400nm. Ultraviolet irradiance meters are now widely used in many areas. However, as the development of science and technology, especially in the field of light-curing industry, there are more and more UV energy meters or UV-integrators need to be measured. Because the structure, wavelength band and measured power intensity of UV energy meters are different from traditional UV irradiance meters, it is important for us to take research on the calibration. With reference to JJG879-2002, we SIMT have independently developed the UV energy calibration device and the standard of operation and experimental methods for UV energy calibration in detail. In the calibration process of UV energy meter, many influencing factors will affect the final results, including different UVA-band UV light sources, different spectral response for different brands of UV energy meters, instability and no uniformity of UV light source and temperature. Therefore we need to take all of these factors into consideration to improve accuracy in UV energy calibration.

  7. Precision Spectrophotometric Calibration System for Dark Energy Instruments

    SciTech Connect

    Schubnell, Michael S.

    2015-06-30

    For this research we build a precision calibration system and carried out measurements to demonstrate the precision that can be achieved with a high precision spectrometric calibration system. It was shown that the system is capable of providing a complete spectrophotometric calibration at the sub-pixel level. The calibration system uses a fast, high precision monochromator that can quickly and efficiently scan over an instrument’s entire spectral range with a spectral line width of less than 0.01 nm corresponding to a fraction of a pixel on the CCD. The system was extensively evaluated in the laboratory. Our research showed that a complete spectrophotometric calibration standard for spectroscopic survey instruments such as DESI is possible. The monochromator precision and repeatability to a small fraction of the DESI spectrograph LSF was demonstrated with re-initialization on every scan and thermal drift compensation by locking to multiple external line sources. A projector system that mimics telescope aperture for point source at infinity was demonstrated.

  8. Calibrating a tensor magnetic gradiometer using spin data

    USGS Publications Warehouse

    Bracken, Robert E.; Smith, David V.; Brown, Philip J.

    2005-01-01

    Scalar magnetic data are often acquired to discern characteristics of geologic source materials and buried objects. It is evident that a great deal can be done with scalar data, but there are significant advantages to direct measurement of the magnetic gradient tensor in applications with nearby sources, such as unexploded ordnance (UXO). To explore these advantages, we adapted a prototype tensor magnetic gradiometer system (TMGS) and successfully implemented a data-reduction procedure. One of several critical reduction issues is the precise determination of a large group of calibration coefficients for the sensors and sensor array. To resolve these coefficients, we devised a spin calibration method, after similar methods of calibrating space-based magnetometers (Snare, 2001). The spin calibration procedure consists of three parts: (1) collecting data by slowly revolving the sensor array in the Earth?s magnetic field, (2) deriving a comprehensive set of coefficients from the spin data, and (3) applying the coefficients to the survey data. To show that the TMGS functions as a tensor gradiometer, we conducted an experimental survey that verified that the reduction procedure was effective (Bracken and Brown, in press). Therefore, because it was an integral part of the reduction, it can be concluded that the spin calibration was correctly formulated with acceptably small errors.

  9. Waveguide Calibrator for Multi-Element Probe Calibration

    NASA Technical Reports Server (NTRS)

    Sommerfeldt, Scott D.; Blotter, Jonathan D.

    2007-01-01

    A calibrator, referred to as the spider design, can be used to calibrate probes incorporating multiple acoustic sensing elements. The application is an acoustic energy density probe, although the calibrator can be used for other types of acoustic probes. The calibrator relies on the use of acoustic waveguide technology to produce the same acoustic field at each of the sensing elements. As a result, the sensing elements can be separated from each other, but still calibrated through use of the acoustic waveguides. Standard calibration techniques involve placement of an individual microphone into a small cavity with a known, uniform pressure to perform the calibration. If a cavity is manufactured with sufficient size to insert the energy density probe, it has been found that a uniform pressure field can only be created at very low frequencies, due to the size of the probe. The size of the energy density probe prevents one from having the same pressure at each microphone in a cavity, due to the wave effects. The "spider" design probe is effective in calibrating multiple microphones separated from each other. The spider design ensures that the same wave effects exist for each microphone, each with an indivdual sound path. The calibrator s speaker is mounted at one end of a 14-cm-long and 4.1-cm diameter small plane-wave tube. This length was chosen so that the first evanescent cross mode of the plane-wave tube would be attenuated by about 90 dB, thus leaving just the plane wave at the termination plane of the tube. The tube terminates with a small, acrylic plate with five holes placed symmetrically about the axis of the speaker. Four ports are included for the four microphones on the probe. The fifth port is included for the pre-calibrated reference microphone. The ports in the acrylic plate are in turn connected to the probe sensing elements via flexible PVC tubes. These five tubes are the same length, so the acoustic wave effects are the same in each tube. The

  10. Consequences of Secondary Calibrations on Divergence Time Estimates

    PubMed Central

    Schenk, John J.

    2016-01-01

    Secondary calibrations (calibrations based on the results of previous molecular dating studies) are commonly applied in divergence time analyses in groups that lack fossil data; however, the consequences of applying secondary calibrations in a relaxed-clock approach are not fully understood. I tested whether applying the posterior estimate from a primary study as a prior distribution in a secondary study results in consistent age and uncertainty estimates. I compared age estimates from simulations with 100 randomly replicated secondary trees. On average, the 95% credible intervals of node ages for secondary estimates were significantly younger and narrower than primary estimates. The primary and secondary age estimates were significantly different in 97% of the replicates after Bonferroni corrections. Greater error in magnitude was associated with deeper than shallower nodes, but the opposite was found when standardized by median node age, and a significant positive relationship was determined between the number of tips/age of secondary trees and the total amount of error. When two secondary calibrated nodes were analyzed, estimates remained significantly different, and although the minimum and median estimates were associated with less error, maximum age estimates and credible interval widths had greater error. The shape of the prior also influenced error, in which applying a normal, rather than uniform, prior distribution resulted in greater error. Secondary calibrations, in summary, lead to a false impression of precision and the distribution of age estimates shift away from those that would be inferred by the primary analysis. These results suggest that secondary calibrations should not be applied as the only source of calibration in divergence time analyses that test time-dependent hypotheses until the additional error associated with secondary calibrations is more properly modeled to take into account increased uncertainty in age estimates. PMID:26824760

  11. DOE radiological calibrations intercomparison program: Results of fiscal year 1986

    SciTech Connect

    Cummings, F.M.; Roberson, P.L.; McDonald, J.C.

    1987-05-01

    The Department of Energy Radiological Calibration Intercomparison Program was initiated in January 1986, under the research portion of the DOE Laboratory Accreditation Program. The program operates via the exchange of transfer standards, consisting of instrument sets and standard secondary beta sources. There are two instrument sets and the scheduled use has been staggered such that one set is available for use during each month. One set of secondary standard beta sources is available for use bimonthly. During the 1986 fiscal year, five laboratories used the instrument sets and three laboratories used the beta source set. Results were reported for all the measurements. The average and one standard deviation of the ratios of participant results to Pacific Northwest Laboratory calibration values were 1.12 +- 0.17 for gamma measurements. Those ratios for the gamma measurements varied from 0.98 to 3.06. The larger differences of results from measurements performed at two facilities were directly attributable to unfamiliarity with the intercomparison instruments. The average and one standard deviation of the ratios of participant results to PNL calibration values obtained using the secondary /sup 90/Sr beta source was 1.02 +- 0.05, which is well within measurement uncertainties. The one participant who performed measurements using /sup 147/Pm and /sup 204/Tl sources obtained ratios of 0.68 and 1.11, respectively. No measurements were performed using neutron or x-ray sources.

  12. 21 CFR 868.6400 - Calibration gas.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Calibration gas. 868.6400 Section 868.6400 Food... DEVICES ANESTHESIOLOGY DEVICES Miscellaneous § 868.6400 Calibration gas. (a) Identification. A calibration gas is a device consisting of a container of gas of known concentration intended to calibrate...

  13. 21 CFR 868.6400 - Calibration gas.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Calibration gas. 868.6400 Section 868.6400 Food... DEVICES ANESTHESIOLOGY DEVICES Miscellaneous § 868.6400 Calibration gas. (a) Identification. A calibration gas is a device consisting of a container of gas of known concentration intended to calibrate...

  14. 21 CFR 868.6400 - Calibration gas.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Calibration gas. 868.6400 Section 868.6400 Food... DEVICES ANESTHESIOLOGY DEVICES Miscellaneous § 868.6400 Calibration gas. (a) Identification. A calibration gas is a device consisting of a container of gas of known concentration intended to calibrate...

  15. 21 CFR 868.6400 - Calibration gas.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Calibration gas. 868.6400 Section 868.6400 Food... DEVICES ANESTHESIOLOGY DEVICES Miscellaneous § 868.6400 Calibration gas. (a) Identification. A calibration gas is a device consisting of a container of gas of known concentration intended to calibrate...

  16. 21 CFR 868.6400 - Calibration gas.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Calibration gas. 868.6400 Section 868.6400 Food... DEVICES ANESTHESIOLOGY DEVICES Miscellaneous § 868.6400 Calibration gas. (a) Identification. A calibration gas is a device consisting of a container of gas of known concentration intended to calibrate...

  17. FTIR Calibration Methods and Issues

    NASA Astrophysics Data System (ADS)

    Perron, Gaetan

    Over the past 10 years, several space-borne FTIR missions were launched for atmospheric research, environmental monitoring and meteorology. One can think of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) launched by the European Space Agency, the Atmospheric Chemistry Experiment (ACE) launched by the Canadian Space Agency, the Tropospheric Emission Spectrometer (TES) launched by NASA and the Infrared Atmospheric Sounding Interferometer (IASI) launched by Eumetsat in Europe. Others are near to be launched, namely the Cross-track Infrared Sounder (CrIS) from the Integrated Program Of- fice in the United States and the Thermal And Near infrared Sensor for carbon Observation (TANSO) from the Japan Aerospace Exploration Agency. Moreover, several missions under definition foresee the use of this technology as sensor, e.g. Meteosat Third Generation (MTG), Eumetsat Polar System (EPS) and the Premier mission, one of the six candidates of the next ESA Earth Explorer Core Mission. In order to produce good quality products, calibration is essential. Calibrated data is the output of three main sub-systems that are tightly coupled: the instrument, the calibration targets and the level 1B processor. Calibration requirements must be carefully defined and propagated to each sub-system. Often, they are carried out by different parties which add to the complexity. Under budget and schedule pressure, some aspects are sometimes neglected and jeopardized final quality. For space-borne FTIR, level 1B outputs are spectra that are radiometrically, spectrally calibrated and geolocated. Radiometric calibration means to assign an intensity value in units to the y-axis. Spectral calibration means to assign to the x-axis the proper frequency value in units. Finally, geolocated means to assign a target position over the earth geoid i.e. longitude, latitude and altitude. This paper will present calibration methods and issues related to space-borne FTIR missions, e.g. two

  18. Automatic magnetometer calibration with small space coverage

    NASA Astrophysics Data System (ADS)

    Wahdan, Ahmed

    The use of a standalone Global Navigation Satellite System (GNSS) has proved to be insufficient when navigating indoors or in urban canyons due to multipath or obstruction. Recent technological advances in low cost micro-electro-mechanical system (MEMS) -- based sensors (like accelerometers, gyroscopes and magnetometers) enabled the development of sensor-based navigation systems. Although MEMS sensors are low-cost, lightweight, small size, and have low-power consumption, they have complex error characteristics. Accurate computation of the heading angle (azimuth) is one of the most important aspects of any navigation system. It can be computed either by gyroscopes or magnetometers. Gyroscopes are inertial sensors that can provide the angular rate from which the heading can be calculated, however, their outputs drift with time. Moreover, the accumulated errors due to mathematical integration, performed to obtain the heading angle, lead to large heading errors. On the other hand, magnetometers do not suffer from drift and the calculation of heading does not suffer from error accumulation. They can provide an absolute heading from the magnetic north by sensing the earth's magnetic field. However, magnetometer readings are usually affected by magnetic fields, other than the earth magnetic field, and by other error sources; therefore magnetometer calibration is required to use magnetometer as a reliable source of heading in navigation applications. In this thesis, a framework for fast magnetometer calibration is proposed. This framework requires little space coverage with no user involvement in the calibration process, and does not need specific movements to be performed. The proposed techniques are capable of performing both 2-dimensional (2D) and 3-dimensional (3D) calibration for magnetometers. They are developed to consider different scenarios suitable for different applications, and can benefit from natural device movements. Some applications involve tethering the

  19. Summary of AXAF calibration requirements

    NASA Technical Reports Server (NTRS)

    Kellogg, E.

    1993-01-01

    The following summarizes requirements on the High Resolution Mirror Assembly (HRMA) and HRMA/SI calibration. The lists of calibration measurements assume that the HRMA meets the CTT requirement that the XRCF test environment shall have not more than a 10 percent effect on the encircled energy in 1 arcsec and that it can be calibrated to 1 percent. This implies that the offloading scheme has been implemented in the HRMA. It should be remembered that there are additional calibrations needed for: aspect system; tracking; gyros; other parts of the PCAS; spacecraft timing and checks on timing accuracy for all SIs after integration in the spacecraft; ficucial lights and periscope; alignments; optical metrology data: lengths and diameters with errors on mirror elements and optical interferometer data on surface figure; and throughput and imaging stability test: an end-to-end test that can be used after the XRCF to verify that the x-ray throughput and imaging quality have not been degraded. The tables presented give a summary of the integration times for HRMA and HRMA/SI calibration.

  20. Internal to external wavelength calibration

    NASA Astrophysics Data System (ADS)

    Sahu, Kailash C.

    1999-01-01

    The spectra of Hen 1357 (the Stingray nebula) were used to check the internal to external wavelength calibration of the STIS first order CCD modes. The radial velocity of the Stingray nebula is known to high accuracy (< 1 km/sec) and the line with of the nebular line is very narrow (< 8 km/sec for the integrated nebula). Thus the observations of the Stingray nebula are ideal to check the internal to external wavelength calibration of the first order modes. The observations were taken in G430L and G750M modes using a 52 x 0.05 arcsec slit covering the wavelength range 2900 to 5700 A and 6295 to 6867 A, respectively. The observed wavelength range includes many nebular emission lines. The wavelengths of the nebular lines derived using the pipeline internal wavelength calibration were compared with the wavelengths derived from other ground based observations. In all cases, the wavelength match between the two is of the same order as the accuracy to which the line center can be measured. These results imply that there is no significant offset between the internal and external wavelength calibrations for these modes. The HDF-S QSO observations were also used for this test both for the first order and the Echelle modes. The results of the HDF-S QSO observations further confirm the above finding for the first order modes, and imply that there is no significant offset between the internal and external wavelength calibration for the Echelle modes.