Carnegie Hubble Program: A Mid-Infrared Calibration of the Hubble Constant

Science.gov (United States)

Freedman, Wendy L.; Madore, Barry F.; Scowcroft, Victoria; Burns, Chris; Monson, Andy; Persson, S. Eric; Seibert, Mark; Rigby, Jane

2012-01-01

Using a mid-infrared calibration of the Cepheid distance scale based on recent observations at 3.6 micrometers with the Spitzer Space Telescope, we have obtained a new, high-accuracy calibration of the Hubble constant. We have established the mid-IR zero point of the Leavitt law (the Cepheid period-luminosity relation) using time-averaged 3.6 micrometers data for 10 high-metallicity, MilkyWay Cepheids having independently measured trigonometric parallaxes. We have adopted the slope of the PL relation using time-averaged 3.6micrometers data for 80 long-period Large Magellanic Cloud (LMC) Cepheids falling in the period range 0.8 < log(P) < 1.8.We find a new reddening-corrected distance to the LMC of 18.477 +/- 0.033 (systematic) mag. We re-examine the systematic uncertainties in H(sub 0), also taking into account new data over the past decade. In combination with the new Spitzer calibration, the systematic uncertainty in H(sub 0) over that obtained by the Hubble Space Telescope Key Project has decreased by over a factor of three. Applying the Spitzer calibration to the Key Project sample, we find a value of H(sub 0) = 74.3 with a systematic uncertainty of +/-2.1 (systematic) kilometers per second Mpc(sup -1), corresponding to a 2.8% systematic uncertainty in the Hubble constant. This result, in combination with WMAP7measurements of the cosmic microwave background anisotropies and assuming a flat universe, yields a value of the equation of state for dark energy, w(sub 0) = -1.09 +/- 0.10. Alternatively, relaxing the constraints on flatness and the numbers of relativistic species, and combining our results with those of WMAP7, Type Ia supernovae and baryon acoustic oscillations yield w(sub 0) = -1.08 +/- 0.10 and a value of N(sub eff) = 4.13 +/- 0.67, mildly consistent with the existence of a fourth neutrino species.

Accurate Calibration and Uncertainty Estimation of the Normal Spring Constant of Various AFM Cantilevers

Directory of Open Access Journals (Sweden)

Yunpeng Song

2015-03-01

Full Text Available Measurement of force on a micro- or nano-Newton scale is important when exploring the mechanical properties of materials in the biophysics and nanomechanical fields. The atomic force microscope (AFM is widely used in microforce measurement. The cantilever probe works as an AFM force sensor, and the spring constant of the cantilever is of great significance to the accuracy of the measurement results. This paper presents a normal spring constant calibration method with the combined use of an electromagnetic balance and a homemade AFM head. When the cantilever presses the balance, its deflection is detected through an optical lever integrated in the AFM head. Meanwhile, the corresponding bending force is recorded by the balance. Then the spring constant can be simply calculated using Hooke’s law. During the calibration, a feedback loop is applied to control the deflection of the cantilever. Errors that may affect the stability of the cantilever could be compensated rapidly. Five types of commercial cantilevers with different shapes, stiffness, and operating modes were chosen to evaluate the performance of our system. Based on the uncertainty analysis, the expanded relative standard uncertainties of the normal spring constant of most measured cantilevers are believed to be better than 2%.

Microelectromechanical system device for calibration of atomic force microscope cantilever spring constants between 0.01 and 4 N/m

International Nuclear Information System (INIS)

Cumpson, Peter J.; Hedley, John; Clifford, Charles A.; Chen Xinyong; Allen, Stephanie

2004-01-01

Calibration of atomic force microscope (AFM) cantilevers is necessary for the measurement of nano-newton and pico-newton forces, which are critical to analytical application of AFM in the analysis of polymer surfaces, biological structures and organic molecules. Previously we have described microfabricated array of reference spring (MARS) devices for AFM cantilever spring-constant calibration. Hitherto, these have been limited to the calibration of AFM cantilevers above 0.03 N/m, although they can be used to calibrate cantilevers of lower stiffness with reduced accuracy. Below this limit MARS devices similar to the designs hitherto described would be fragile and difficult to manufacture with reasonable yield. In this work we describe a device we call torsional MARS. This is a large-area torsional mechanical resonator, manufactured by bulk micromachining of a 'silicon-on-insulator' wafer. By measuring its torsional oscillation accurately in vacuum we can deduce its torsional spring constant. The torsional reference spring spans the range of spring constant (from 4 down to 0.01 N/m) that is important in biological AFM, allowing even the most compliant AFM cantilever to be calibrated easily and rapidly

Wavelength calibration with PMAS at 3.5 m Calar Alto Telescope using a tunable astro-comb

Science.gov (United States)

Chavez Boggio, J. M.; Fremberg, T.; Bodenmüller, D.; Sandin, C.; Zajnulina, M.; Kelz, A.; Giannone, D.; Rutowska, M.; Moralejo, B.; Roth, M. M.; Wysmolek, M.; Sayinc, H.

2018-05-01

On-sky tests conducted with an astro-comb using the Potsdam Multi-Aperture Spectrograph (PMAS) at the 3.5 m Calar Alto Telescope are reported. The proposed astro-comb approach is based on cascaded four-wave mixing between two lasers propagating through dispersion optimized nonlinear fibers. This approach allows for a line spacing that can be continuously tuned over a broad range (from tens of GHz to beyond 1 THz) making it suitable for calibration of low- medium- and high-resolution spectrographs. The astro-comb provides 300 calibration lines and his line-spacing is tracked with a wavemeter having 0.3 pm absolute accuracy. First, we assess the accuracy of Neon calibration by measuring the astro-comb lines with (Neon calibrated) PMAS. The results are compared with expected line positions from wavemeter measurement showing an offset of ∼5-20 pm (4%-16% of one resolution element). This might be the footprint of the accuracy limits from actual Neon calibration. Then, the astro-comb performance as a calibrator is assessed through measurements of the Ca triplet from stellar objects HD3765 and HD219538 as well as with the sky line spectrum, showing the advantage of the proposed astro-comb for wavelength calibration at any resolution.

A Comparative Investigation of the Combined Effects of Pre-Processing, Wavelength Selection, and Regression Methods on Near-Infrared Calibration Model Performance.

Science.gov (United States)

Wan, Jian; Chen, Yi-Chieh; Morris, A Julian; Thennadil, Suresh N

2017-07-01

Near-infrared (NIR) spectroscopy is being widely used in various fields ranging from pharmaceutics to the food industry for analyzing chemical and physical properties of the substances concerned. Its advantages over other analytical techniques include available physical interpretation of spectral data, nondestructive nature and high speed of measurements, and little or no need for sample preparation. The successful application of NIR spectroscopy relies on three main aspects: pre-processing of spectral data to eliminate nonlinear variations due to temperature, light scattering effects and many others, selection of those wavelengths that contribute useful information, and identification of suitable calibration models using linear/nonlinear regression . Several methods have been developed for each of these three aspects and many comparative studies of different methods exist for an individual aspect or some combinations. However, there is still a lack of comparative studies for the interactions among these three aspects, which can shed light on what role each aspect plays in the calibration and how to combine various methods of each aspect together to obtain the best calibration model. This paper aims to provide such a comparative study based on four benchmark data sets using three typical pre-processing methods, namely, orthogonal signal correction (OSC), extended multiplicative signal correction (EMSC) and optical path-length estimation and correction (OPLEC); two existing wavelength selection methods, namely, stepwise forward selection (SFS) and genetic algorithm optimization combined with partial least squares regression for spectral data (GAPLSSP); four popular regression methods, namely, partial least squares (PLS), least absolute shrinkage and selection operator (LASSO), least squares support vector machine (LS-SVM), and Gaussian process regression (GPR). The comparative study indicates that, in general, pre-processing of spectral data can play a significant

Simultaneous identification of optical constants and PSD of spherical particles by multi-wavelength scattering-transmittance measurement

Science.gov (United States)

Zhang, Jun-You; Qi, Hong; Ren, Ya-Tao; Ruan, Li-Ming

2018-04-01

An accurate and stable identification technique is developed to retrieve the optical constants and particle size distributions (PSDs) of particle system simultaneously from the multi-wavelength scattering-transmittance signals by using the improved quantum particle swarm optimization algorithm. The Mie theory are selected to calculate the directional laser intensity scattered by particles and the spectral collimated transmittance. The sensitivity and objective function distribution analysis were conducted to evaluate the mathematical properties (i.e. ill-posedness and multimodality) of the inverse problems under three different optical signals combinations (i.e. the single-wavelength multi-angle light scattering signal, the single-wavelength multi-angle light scattering and spectral transmittance signal, and the multi-angle light scattering and spectral transmittance signal). It was found the best global convergence performance can be obtained by using the multi-wavelength scattering-transmittance signals. Meanwhile, the present technique have been tested under different Gaussian measurement noise to prove its feasibility in a large solution space. All the results show that the inverse technique by using multi-wavelength scattering-transmittance signals is effective and suitable for retrieving the optical complex refractive indices and PSD of particle system simultaneously.

Effects of the pulse-driven magnetic field detuning on the calibration of coil constants while using noble gases

Directory of Open Access Journals (Sweden)

Jing Wang

2018-04-01

Full Text Available In the calibration of coil constants using the Free Induction Decay (FID signal of noble gases, we analyse the effects of the pulse-driven magnetic field detuning on the calibration results. This method is based on the inverse relation between the π/2 pulse duration and its amplitude. We confirmed that obtaining a precise frequency is a prerequisite for ensuring the accuracy of research using the initial amplitude of the FID signal. In this paper, the spin dynamics of noble gases and its time-domain solution under the driving pulse have been discussed with regard to different detuning ranges. Experimental results are in good agreement with our theoretical predictions, which indicate the correctness of our theoretical deduction. Therefore, the frequency of the pulse-driven magnetic field is an important factor to the calibration of coil constants, it should be determined with a high degree of accuracy.

An absolute calibration method of an ethyl alcohol biosensor based on wavelength-modulated differential photothermal radiometry.

Science.gov (United States)

Liu, Yi Jun; Mandelis, Andreas; Guo, Xinxin

2015-11-01

In this work, laser-based wavelength-modulated differential photothermal radiometry (WM-DPTR) is applied to develop a non-invasive in-vehicle alcohol biosensor. WM-DPTR features unprecedented ethanol-specificity and sensitivity by suppressing baseline variations through a differential measurement near the peak and baseline of the mid-infrared ethanol absorption spectrum. Biosensor signal calibration curves are obtained from WM-DPTR theory and from measurements in human blood serum and ethanol solutions diffused from skin. The results demonstrate that the WM-DPTR-based calibrated alcohol biosensor can achieve high precision and accuracy for the ethanol concentration range of 0-100 mg/dl. The high-performance alcohol biosensor can be incorporated into ignition interlocks that could be fitted as a universal accessory in vehicles in an effort to reduce incidents of drinking and driving.

Spring constant calibration of atomic force microscope cantilevers of arbitrary shape

Energy Technology Data Exchange (ETDEWEB)

Sader, John E. [Department of Mathematics and Statistics, University of Melbourne, Victoria 3010 (Australia); Kavli Nanoscience Institute and Department of Physics, California Institute of Technology, Pasadena, California 91125 (United States); Sanelli, Julian A.; Adamson, Brian D.; Bieske, Evan J. [School of Chemistry, University of Melbourne, Victoria 3010 (Australia); Monty, Jason P.; Marusic, Ivan [Department of Mechanical Engineering, University of Melbourne, Victoria 3010 (Australia); Wei Xingzhan; Mulvaney, Paul [School of Chemistry, University of Melbourne, Victoria 3010 (Australia); Bio21 Institute, University of Melbourne, Victoria 3010 (Australia); Crawford, Simon A. [School of Botany, University of Melbourne, Victoria 3010 (Australia); Friend, James R. [Melbourne Centre for Nanofabrication, Clayton, Victoria 3800 (Australia); MicroNanophysics Research Laboratory, RMIT University, Melbourne, Victoria 3001 (Australia)

2012-10-15

The spring constant of an atomic force microscope cantilever is often needed for quantitative measurements. The calibration method of Sader et al. [Rev. Sci. Instrum. 70, 3967 (1999)] for a rectangular cantilever requires measurement of the resonant frequency and quality factor in fluid (typically air), and knowledge of its plan view dimensions. This intrinsically uses the hydrodynamic function for a cantilever of rectangular plan view geometry. Here, we present hydrodynamic functions for a series of irregular and non-rectangular atomic force microscope cantilevers that are commonly used in practice. Cantilever geometries of arrow shape, small aspect ratio rectangular, quasi-rectangular, irregular rectangular, non-ideal trapezoidal cross sections, and V-shape are all studied. This enables the spring constants of all these cantilevers to be accurately and routinely determined through measurement of their resonant frequency and quality factor in fluid (such as air). An approximate formulation of the hydrodynamic function for microcantilevers of arbitrary geometry is also proposed. Implementation of the method and its performance in the presence of uncertainties and non-idealities is discussed, together with conversion factors for the static and dynamic spring constants of these cantilevers. These results are expected to be of particular value to the design and application of micro- and nanomechanical systems in general.

Spring constant calibration of atomic force microscope cantilevers of arbitrary shape

International Nuclear Information System (INIS)

Sader, John E.; Sanelli, Julian A.; Adamson, Brian D.; Bieske, Evan J.; Monty, Jason P.; Marusic, Ivan; Wei Xingzhan; Mulvaney, Paul; Crawford, Simon A.; Friend, James R.

2012-01-01

The spring constant of an atomic force microscope cantilever is often needed for quantitative measurements. The calibration method of Sader et al. [Rev. Sci. Instrum. 70, 3967 (1999)] for a rectangular cantilever requires measurement of the resonant frequency and quality factor in fluid (typically air), and knowledge of its plan view dimensions. This intrinsically uses the hydrodynamic function for a cantilever of rectangular plan view geometry. Here, we present hydrodynamic functions for a series of irregular and non-rectangular atomic force microscope cantilevers that are commonly used in practice. Cantilever geometries of arrow shape, small aspect ratio rectangular, quasi-rectangular, irregular rectangular, non-ideal trapezoidal cross sections, and V-shape are all studied. This enables the spring constants of all these cantilevers to be accurately and routinely determined through measurement of their resonant frequency and quality factor in fluid (such as air). An approximate formulation of the hydrodynamic function for microcantilevers of arbitrary geometry is also proposed. Implementation of the method and its performance in the presence of uncertainties and non-idealities is discussed, together with conversion factors for the static and dynamic spring constants of these cantilevers. These results are expected to be of particular value to the design and application of micro- and nanomechanical systems in general.

Calibrating the SNfactory Integral Field Spectrograph (SNIFS) with SCALA

Science.gov (United States)

Küsters, Daniel; Lombardo, Simona; Kowalski, Marek; Aldering, Greg; Nordin, Jakob; Rigault, Mickael

2016-08-01

The SNIFS CALibration Apparatus (SCALA), a device to calibrate the Supernova Integral Field Spectrograph on the University Hawaii 2.2m telescope, was developed and installed in Spring 2014. SCALA produces an artificial planet with a diameter of 1° and a constant surface brightness. The wavelength of the beam can be tuned between 3200 Å and 10000 Å and has a bandwidth of 35 Å. The amount of light injected into the telescope is monitored with NIST calibrated photodiodes. SCALA was upgraded in 2015 with a mask installed at the entrance pupil of the UH88 telescope, ensuring that the illumination of the telescope by stars is similar to that of SCALA. With this setup, a first calibration run was performed in conjunction with the spectrophotometric observations of standard stars. We present first estimates for the expected systematic uncertainties of the in-situ calibration and discuss the results of tests that examine the influence of stray light produced in the optics.

FIMS Wavelength Calibration via Airglow Line Observations

Directory of Open Access Journals (Sweden)

Dae-Hee Lee

2004-12-01

Full Text Available Far-ultraviolet Imaging Spectrograph (FIMS is the main payload of the Korea's first scientific micro satellite STSAT-1, which was launched at Sep. 27 2003 successfully. Major objective of FIMS is observing hot gas in the Galaxy in FUV bands to diagnose the energy flow models of the interstellar medium. Supernova remnants, molecular clouds, and Aurora emission in the geomagnetic pole regions are specific targets for pointing observation. Although the whole system was calibrated before launch, it is essential to perform on-orbit calibration for data analysis. For spectral calibration, we observed airglow lines in the atmosphere since they provide good spectral references. We identify and compare the observed airglow lines with model calculations, and correct the spectral distortion appeared in the detector system to improve the spectral resolution of the system.

Calibration of the fine-structure constant of graphene by time-dependent density-functional theory

Science.gov (United States)

Sindona, A.; Pisarra, M.; Vacacela Gomez, C.; Riccardi, P.; Falcone, G.; Bellucci, S.

2017-11-01

One of the amazing properties of graphene is the ultrarelativistic behavior of its loosely bound electrons, mimicking massless fermions that move with a constant velocity, inversely proportional to a fine-structure constant αg of the order of unity. The effective interaction between these quasiparticles is, however, better controlled by the coupling parameter αg*=αg/ɛ , which accounts for the dynamic screening due to the complex permittivity ɛ of the many-valence electron system. This concept was introduced in a couple of previous studies [Reed et al., Science 330, 805 (2010) and Gan et al., Phys. Rev. B 93, 195150 (2016)], where inelastic x-ray scattering measurements on crystal graphite were converted into an experimentally derived form of αg* for graphene, over an energy-momentum region on the eV Å -1 scale. Here, an accurate theoretical framework is provided for αg*, using time-dependent density-functional theory in the random-phase approximation, with a cutoff in the interaction between excited electrons in graphene, which translates to an effective interlayer interaction in graphite. The predictions of the approach are in excellent agreement with the above-mentioned measurements, suggesting a calibration method to substantially improve the experimental derivation of αg*, which tends to a static limiting value of ˜0.14 . Thus, the ab initio calibration procedure outlined demonstrates the accuracy of perturbation expansion treatments for the two-dimensional gas of massless Dirac fermions in graphene, in parallel with quantum electrodynamics.

HIGH-PRECISION ASTROMETRIC MILLIMETER VERY LONG BASELINE INTERFEROMETRY USING A NEW METHOD FOR MULTI-FREQUENCY CALIBRATION

Energy Technology Data Exchange (ETDEWEB)

Dodson, Richard; Rioja, María J. [International Centre for Radio Astronomy Research, M468, The University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009 (Australia); Molina, Sol N.; Gómez, José L., E-mail: richard.dodson@icrar.org [Instituto de Astrofísica de Andalucía-CSIC, Glorieta de la Astronomía s/n, E-18008 Granada (Spain)

2017-01-10

In this paper we describe a new approach for millimeter Very Long Baseline Interferometry (mm-VLBI) calibration that provides bona-fide astrometric alignment of the millimeter-wavelength images from a single source, for the measurement of frequency-dependent effects, such as “core-shifts” near the black hole of active galactic nucleus jets. We achieve our astrometric alignment by solving first for the ionospheric (dispersive) contributions using wide-band centimeter-wavelength observations. Second, we solve for the tropospheric (non-dispersive) contributions by using fast frequency-switching at the target millimeter-wavelengths. These solutions can be scaled and transferred from low frequency to the high frequency. To complete the calibration chain an additional step is required to remove a residual constant phase offset on each antenna. The result is an astrometric calibration and the measurement of the core-shift between 22 and 43 GHz for the jet in BL Lacertae to be −8 ± 5, 20 ± 6 μ as, in R.A. and decl., respectively. By comparison to conventional phase referencing at centimeter-wavelengths we are able to show that this core shift at millimeter-wavelengths is significantly less than what would be predicted by extrapolating the low-frequency result, which closely followed the predictions of the Blandford and Königl conical jet model. As such it would be the first demonstration for the association of the VLBI core with a recollimation shock, normally hidden at low frequencies due to the optical depth, which could be responsible for the γ -ray production in blazar jets.

HIGH-PRECISION ASTROMETRIC MILLIMETER VERY LONG BASELINE INTERFEROMETRY USING A NEW METHOD FOR MULTI-FREQUENCY CALIBRATION

International Nuclear Information System (INIS)

Dodson, Richard; Rioja, María J.; Molina, Sol N.; Gómez, José L.

2017-01-01

In this paper we describe a new approach for millimeter Very Long Baseline Interferometry (mm-VLBI) calibration that provides bona-fide astrometric alignment of the millimeter-wavelength images from a single source, for the measurement of frequency-dependent effects, such as “core-shifts” near the black hole of active galactic nucleus jets. We achieve our astrometric alignment by solving first for the ionospheric (dispersive) contributions using wide-band centimeter-wavelength observations. Second, we solve for the tropospheric (non-dispersive) contributions by using fast frequency-switching at the target millimeter-wavelengths. These solutions can be scaled and transferred from low frequency to the high frequency. To complete the calibration chain an additional step is required to remove a residual constant phase offset on each antenna. The result is an astrometric calibration and the measurement of the core-shift between 22 and 43 GHz for the jet in BL Lacertae to be −8 ± 5, 20 ± 6 μ as, in R.A. and decl., respectively. By comparison to conventional phase referencing at centimeter-wavelengths we are able to show that this core shift at millimeter-wavelengths is significantly less than what would be predicted by extrapolating the low-frequency result, which closely followed the predictions of the Blandford and Königl conical jet model. As such it would be the first demonstration for the association of the VLBI core with a recollimation shock, normally hidden at low frequencies due to the optical depth, which could be responsible for the γ -ray production in blazar jets.

Fermentation process tracking through enhanced spectral calibration modeling.

Science.gov (United States)

Triadaphillou, Sophia; Martin, Elaine; Montague, Gary; Norden, Alison; Jeffkins, Paul; Stimpson, Sarah

2007-06-15

The FDA process analytical technology (PAT) initiative will materialize in a significant increase in the number of installations of spectroscopic instrumentation. However, to attain the greatest benefit from the data generated, there is a need for calibration procedures that extract the maximum information content. For example, in fermentation processes, the interpretation of the resulting spectra is challenging as a consequence of the large number of wavelengths recorded, the underlying correlation structure that is evident between the wavelengths and the impact of the measurement environment. Approaches to the development of calibration models have been based on the application of partial least squares (PLS) either to the full spectral signature or to a subset of wavelengths. This paper presents a new approach to calibration modeling that combines a wavelength selection procedure, spectral window selection (SWS), where windows of wavelengths are automatically selected which are subsequently used as the basis of the calibration model. However, due to the non-uniqueness of the windows selected when the algorithm is executed repeatedly, multiple models are constructed and these are then combined using stacking thereby increasing the robustness of the final calibration model. The methodology is applied to data generated during the monitoring of broth concentrations in an industrial fermentation process from on-line near-infrared (NIR) and mid-infrared (MIR) spectrometers. It is shown that the proposed calibration modeling procedure outperforms traditional calibration procedures, as well as enabling the identification of the critical regions of the spectra with regard to the fermentation process.

40 CFR 86.519-90 - Constant volume sampler calibration.

Science.gov (United States)

2010-07-01

... total calibration. Allow the system to stabilize for 3 minutes and repeat the data acquisition. (7) Data... decrease as reflected by lower values for M. Calibrations should be performed at pump startup and after...

On the prospects of cross-calibrating the Cherenkov Telescope Array with an airborne calibration platform

Science.gov (United States)

Brown, Anthony M.

2018-01-01

Recent advances in unmanned aerial vehicle (UAV) technology have made UAVs an attractive possibility as an airborne calibration platform for astronomical facilities. This is especially true for arrays of telescopes spread over a large area such as the Cherenkov Telescope Array (CTA). In this paper, the feasibility of using UAVs to calibrate CTA is investigated. Assuming a UAV at 1km altitude above CTA, operating on astronomically clear nights with stratified, low atmospheric dust content, appropriate thermal protection for the calibration light source and an onboard photodiode to monitor its absolute light intensity, inter-calibration of CTA's telescopes of the same size class is found to be achievable with a 6 - 8 % uncertainty. For cross-calibration of different telescope size classes, a systematic uncertainty of 8 - 10 % is found to be achievable. Importantly, equipping the UAV with a multi-wavelength calibration light source affords us the ability to monitor the wavelength-dependent degradation of CTA telescopes' optical system, allowing us to not only maintain this 6 - 10 % uncertainty after the first few years of telescope deployment, but also to accurately account for the effect of multi-wavelength degradation on the cross-calibration of CTA by other techniques, namely with images of air showers and local muons. A UAV-based system thus provides CTA with several independent and complementary methods of cross-calibrating the optical throughput of individual telescopes. Furthermore, housing environmental sensors on the UAV system allows us to not only minimise the systematic uncertainty associated with the atmospheric transmission of the calibration signal, it also allows us to map the dust content above CTA as well as monitor the temperature, humidity and pressure profiles of the first kilometre of atmosphere above CTA with each UAV flight.

The Use of Color Sensors for Spectrographic Calibration

Science.gov (United States)

Thomas, Neil B.

2018-04-01

The wavelength calibration of spectrographs is an essential but challenging task in many disciplines. Calibration is traditionally accomplished by imaging the spectrum of a light source containing features that are known to appear at certain wavelengths and mapping them to their location on the sensor. This is typically required in conjunction with each scientific observation to account for mechanical and optical variations of the instrument over time, which may span years for certain projects. The method presented here investigates the usage of color itself instead of spectral features to calibrate a spectrograph. The primary advantage of such a calibration is that any broad-spectrum light source such as the sky or an incandescent bulb is suitable. This method allows for calibration using the full optical pathway of the instrument instead of incorporating separate calibration equipment that may introduce errors. This paper focuses on the potential for color calibration in the field of radial velocity astronomy, in which instruments must be finely calibrated for long periods of time to detect tiny Doppler wavelength shifts. This method is not restricted to radial velocity, however, and may find application in any field requiring calibrated spectrometers such as sea water analysis, cellular biology, chemistry, atmospheric studies, and so on. This paper demonstrates that color sensors have the potential to provide calibration with greatly reduced complexity.

Calibration with near-continuous spectral measurements

DEFF Research Database (Denmark)

Nielsen, Henrik Aalborg; Rasmussen, Michael; Madsen, Henrik

2001-01-01

In chemometrics traditional calibration in case of spectral measurements express a quantity of interest (e.g. a concentration) as a linear combination of the spectral measurements at a number of wavelengths. Often the spectral measurements are performed at a large number of wavelengths and in thi...... by an example in which the octane number of gasoline is related to near infrared spectral measurements. The performance is found to be much better that for the traditional calibration methods....

Comparison of kVp and PPV measurements between a constant potential and a clinical X-ray system used for calibration in mammography

Energy Technology Data Exchange (ETDEWEB)

Correa, Eduardo de L.; Vivolo, Vitor; Potiens, Maria da Penha A., E-mail: vivolo@ipen.b, E-mail: mppalbu@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-07-01

The PPV is an electrical quantity that relates the peak voltage with the radiological image contrast, thus having a larger clinical application. By definition, in an X-ray system, the 'PPV is a quantity based on the concept that the radiation generated by a high voltage source with an arbitrary wave source produces the same radiographic contrast that the radiation generated by a high voltage source with an equivalent constant potential'. The Instruments Calibration Laboratory (LCI) of IPEN has the mammography qualities established in a constant potential system (industrial X-ray system), and also in a clinical system (mammograph). The objective of this study was to analyze the PPV behavior in these systems, and try to reach calibration conditions that are more similar to the work conditions in hospitals and clinics. For this, it was used an industrial X-ray (constant potential) and a mammography system (high frequency). The first system has a tungsten (W) target, and additional filtration of aluminum (Al) and molybdenum (Mo), and the second one has a Mo target and additional filtration of Mo and rhodium (Rh). A non-invasive measuring system from PTW model Diavolt was used to PPV determination. The voltages used were 25 kV, 28 kV, 30 kV and 35 kV (calibration qualities in mammography, according to the IEC 61267). The Diavolt was placed one meter from the focal spot in the industrial X-ray system, and 60 cm for the clinical system. (author)

Calibration procedure and wavelength correction for neutron depolarization experiments

International Nuclear Information System (INIS)

Roest, W.; Rekveldt, M.T.

1992-01-01

The neutron polarimeter, for which an extended calibration procedure is described here, enables one to investigate magnetic properties of materials. Such an investigation is carried out by offering a polarized neutron beam in the x-, y- and z-direction successively and, after transmission through the sample, by analysing the polarization in all three directions. The result is a 3x3 depolarization matrix. After the polarizer, the neutron beam has a polarization along the z-direction. Two coil systems creating a magnetic field in the yz-plane perpendicular to the beam direction provide the possibility to direct the polarization in the x-, y- and z-direction by means of Larmor precession of the polarization in these fields. New research areas, where small depolarization effects together with considerable polarization rotation are measured, have caused a need for more accuracy in, and better knowledge of the calibration of the polarimeter. The calibration procedure use up to now and the improvements made on it are described. (orig.)

A new Cassegrain calibration lamp unit for the Blanco Telescope

Science.gov (United States)

Points, S. D.; James, D. J.; Tighe, R.; Montané, A.; David, N.; Martínez, M.

2016-08-01

The f/8 RC-Cassegrain Focus of the Blanco Telescope at Cerro Tololo Inter-American Observatory, hosts two new instruments: COSMOS, a multi-object spectrograph in the visible wavelength range (350 - 1030nm), and ARCoIRIS, a NIR cross-dispersed spectrograph featuring 6 spectral orders spanning 0.8 - 2.45μm. Here we describe a calibration lamp unit designed to deliver the required illumination at the telescope focal plane for both instruments. These requirements are: (1) an f/8 beam of light covering a spot of 92mm diameter (or 10 arcmin) for a wavelength range of 0.35μm through 2.5μm and (2) no saturation of flat-field calibrations for the minimal exposure times permitted by each instrument, and (3) few saturated spectral lines when using the wavelength calibration lamps for the instruments. To meet these requirements this unit contains an adjustable quartz halogen lamp for flat-field calibrations, and one hollow cathode lamp and four penray lamps for wavelength calibrations. The wavelength calibration lamps are selected to provide optimal spectral coverage for the instrument mounted and can be used individually or in sets. The device designed is based on an 8-inch diameter integrating sphere, the output of which is optimized to match the f/8 calibration input delivery system which is a refractive system based on fused-silica lenses. We describe the optical design, the opto-mechanical design, the electronic control and give results of the performance of the system.

Calibration simulation. A calibration Monte-Carlo program for the OPAL jet chamber

International Nuclear Information System (INIS)

Biebel, O.

1989-12-01

A calibration Monte Carlo program has been developed as a tool to investigate the interdependence of track reconstruction and calibration constants. Three categories of calibration effects have been considered: The precise knowledge of sense wire positions, necessary to reconstruct the particle trajectories in the jet chamber. Included are the staggering and the sag of the sense wires as well as tilts and rotations of their support structures. The various contributions to the measured drift time, with special emphasis on the aberration due to the track angle and the presence of a transverse magnetic field. A very precise knowledge of the drift velocity and the Lorentz angle of the drift paths with respect to the drift field is also required. The effects degrading particle identification via energy loss dE/dx. Impurities of the gas mixture and saturation effects depending on the track angle as well as the influence of the pulse shaping-electronics have been studied. These effects have been parametrised with coefficients corresponding to the calibration constants required for track reconstruction. Excellent agreement with the input data has been achieved when determining calibration constants from Monte Carlo data generated with these parametrisations. (orig.) [de

Highly accurate Michelson type wavelength meter that uses a rubidium stabilized 1560 nm diode laser as a wavelength reference

International Nuclear Information System (INIS)

Masuda, Shin; Kanoh, Eiji; Irisawa, Akiyoshi; Niki, Shoji

2009-01-01

We investigated the accuracy limitation of a wavelength meter installed in a vacuum chamber to enable us to develop a highly accurate meter based on a Michelson interferometer in 1550 nm optical communication bands. We found that an error of parts per million order could not be avoided using famous wavelength compensation equations. Chromatic dispersion of the refractive index in air can almost be disregarded when a 1560 nm wavelength produced by a rubidium (Rb) stabilized distributed feedback (DFB) diode laser is used as a reference wavelength. We describe a novel dual-wavelength self-calibration scheme that maintains high accuracy of the wavelength meter. The method uses the fundamental and second-harmonic wavelengths of an Rb-stabilized DFB diode laser. Consequently, a highly accurate Michelson type wavelength meter with an absolute accuracy of 5x10 -8 (10 MHz, 0.08 pm) over a wide wavelength range including optical communication bands was achieved without the need for a vacuum chamber.

The Calibration Home Base for Imaging Spectrometers

Directory of Open Access Journals (Sweden)

Johannes Felix Simon Brachmann

2016-08-01

Full Text Available The Calibration Home Base (CHB is an optical laboratory designed for the calibration of imaging spectrometers for the VNIR/SWIR wavelength range. Radiometric, spectral and geometric calibration as well as the characterization of sensor signal dependency on polarization are realized in a precise and highly automated fashion. This allows to carry out a wide range of time consuming measurements in an ecient way. The implementation of ISO 9001 standards in all procedures ensures a traceable quality of results. Spectral measurements in the wavelength range 380–1000 nm are performed to a wavelength uncertainty of +- 0.1 nm, while an uncertainty of +-0.2 nm is reached in the wavelength range 1000 – 2500 nm. Geometric measurements are performed at increments of 1.7 µrad across track and 7.6 µrad along track. Radiometric measurements reach an absolute uncertainty of +-3% (k=1. Sensor artifacts, such as caused by stray light will be characterizable and correctable in the near future. For now, the CHB is suitable for the characterization of pushbroom sensors, spectrometers and cameras. However, it is planned to extend the CHBs capabilities in the near future such that snapshot hyperspectral imagers can be characterized as well. The calibration services of the CHB are open to third party customers from research institutes as well as industry.

Compact radiometric microwave calibrator

International Nuclear Information System (INIS)

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

2006-01-01

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

Muon Energy Calibration of the MINOS Detectors

Energy Technology Data Exchange (ETDEWEB)

Miyagawa, Paul S. [Somerville College, Oxford (United Kingdom)

2004-01-01

MINOS is a long-baseline neutrino oscillation experiment designed to search for conclusive evidence of neutrino oscillations and to measure the oscillation parameters precisely. MINOS comprises two iron tracking calorimeters located at Fermilab and Soudan. The Calibration Detector at CERN is a third MINOS detector used as part of the detector response calibration programme. A correct energy calibration between these detectors is crucial for the accurate measurement of oscillation parameters. This thesis presents a calibration developed to produce a uniform response within a detector using cosmic muons. Reconstruction of tracks in cosmic ray data is discussed. This data is utilized to calculate calibration constants for each readout channel of the Calibration Detector. These constants have an average statistical error of 1.8%. The consistency of the constants is demonstrated both within a single run and between runs separated by a few days. Results are presented from applying the calibration to test beam particles measured by the Calibration Detector. The responses are calibrated to within 1.8% systematic error. The potential impact of the calibration on the measurement of oscillation parameters by MINOS is also investigated. Applying the calibration reduces the errors in the measured parameters by ~ 10%, which is equivalent to increasing the amount of data by 20%.

Dual-Frequency Bistatic Radar Probing of Mars: Potential and Pitfalls for Depth Sounding at Centimeter Wavelengths

Science.gov (United States)

Simpson, R. A.; Tyler, G. L.; Paetzold, M.; Haeusler, B.; Asmar, S. W.

2009-12-01

Early spacecraft-to-Earth bistatic radar (BSR) probing of Mars' surface emphasized measurement of rms surface slopes on scales of centimeters to a few meters, information of particular interest to the design and deployment of landers and rovers. Shorter wavelengths yielded higher values, consistent with fractal models in which surface texture becomes rougher as the measuring instrument senses more detail. Although Mars Express (MEX) has found the smoothest extraterrestrial solid surface yet observed by radar (0.17 deg rms in the north polar region), its antenna pattern typically illuminates only part of the scattering surface, making rms slope determination difficult. With careful calibration, however, the ratio of echo power in its two orthogonal polarizations can be used to infer the dielectric constant of the surface material from the Fresnel reflection coefficients. Early results showed larger dielectric constant at 12.6 cm than 3.6 cm, consistent with materials which become more densely packed at depth; as the data collection continued, regional variations became apparent. More puzzling, are cases in which the derived dielectric constant is 30 percent larger at the shorter wavelength, suggesting a centimeter of crust (invisible at 12.6 cm wavelength) overlying less dense regolith below. Duricrust layers have been inferred in some of these areas from thermal measurements; and a layer of gravel, stripped of finer particles, could produce similar effects. Earth-to-spacecraft BSR could improve measurement sensitivity by factors of 100-1000; spacecraft-to-spacecraft experiments could improve surface coverage. All three configurations, including the conventional 'downlink' experiments now being conducted, can provide basic information on surface structure to depths of a few centimeters.

New method to calibrate a spinner anemometer

DEFF Research Database (Denmark)

Demurtas, Giorgio; Friis Pedersen, Troels

2014-01-01

The spinner anemometer is a wind sensor, based on three one dimensional sonic sensor probes, mounted on the wind turbine spinner, and an algorithm to convert the wind speeds measured by the three sonic sensors to horizontal wind speed, yaw misalignment and flow inclination angle. The conversion...... algorithm utilizes two constants k1 and k2 that are specific to the spinner and blade root design and to the mounting position of the sonic sensors on the spinner. The two constants are calibrated by means of two different test and instrument set-ups. Both calibrations consider the rotor of the wind turbine...... to be stopped during calibration in order for the rotor induction not to influence on the calibration, so that the spinner anemometer measures ”free” wind values in stopped condition. The calibration of flow angle measurements is made by calibration of the ratio of the two algorithm constants k2=k1 = k...

Electromagnetic Cell Level Calibration for ATLAS Tile Calorimeter Modules

CERN Document Server

Kulchitskii, Yu A; Budagov, Yu A; Khubua, J I; Rusakovitch, N A; Vinogradov, V B; Henriques, A; Davidek, T; Tokar, S; Solodkov, A; Vichou, I

2006-01-01

We have determined the electromagnetic calibration constants of 11% TileCal modules exposed to electron beams with incident angles of 20 and 90 degrees. The gain of all the calorimeter cells have been pre-equalized using the radioactive Cs-source that will be also used in situ. The average values for these modules are equal to: for the flat filter method 1.154+/-0.002 pC/GeV and 1.192+/-0.002 pC/GeV for 20 and 90 degrees, for the fit method 1.040+/-0.002 pC/GeV and 1.068+/-0.003 pC/GeV, respectively. These average values for all cells of calibrated modules agree with the weighted average calibration constants for separate modules within the errors. Using the individual calibration constants for every module the RMS spread value of constants will be 1.9+/-0.1 %. In the case of the global constant this value will be 2.6+/-0.1 %. Finally, we present the global constants which should be used for the electromagnetic calibration of the ATLAS Tile hadronic calorimeter data in the ATHENA framework. These constants ar...

Emission wavelength of multilayer distributed feedback dye lasers

DEFF Research Database (Denmark)

Vannahme, Christoph; Smith, Cameron L. C.; Brøkner Christiansen, Mads

2012-01-01

Precise emission wavelength modeling is essential for understanding and optimization of distributed feedback (DFB) lasers. An analytical approach for determining the emission wavelength based on setting the propagation constant of the Bragg condition and solving for the resulting slab waveguide m...

Research on a high-precision calibration method for tunable lasers

Science.gov (United States)

Xiang, Na; Li, Zhengying; Gui, Xin; Wang, Fan; Hou, Yarong; Wang, Honghai

2018-03-01

Tunable lasers are widely used in the field of optical fiber sensing, but nonlinear tuning exists even for zero external disturbance and limits the accuracy of the demodulation. In this paper, a high-precision calibration method for tunable lasers is proposed. A comb filter is introduced and the real-time output wavelength and scanning rate of the laser are calibrated by linear fitting several time-frequency reference points obtained from it, while the beat signal generated by the auxiliary interferometer is interpolated and frequency multiplied to find more accurate zero crossing points, with these points being used as wavelength counters to resample the comb signal to correct the nonlinear effect, which ensures that the time-frequency reference points of the comb filter are linear. A stability experiment and a strain sensing experiment verify the calibration precision of this method. The experimental result shows that the stability and wavelength resolution of the FBG demodulation can reach 0.088 pm and 0.030 pm, respectively, using a tunable laser calibrated by the proposed method. We have also compared the demodulation accuracy in the presence or absence of the comb filter, with the result showing that the introduction of the comb filter results to a 15-fold wavelength resolution enhancement.

Intercomparison and calibration of dose calibrators used in nuclear medicine facilities

CERN Document Server

Costa, A M D

2003-01-01

The aim of this work was to establish a working standard for intercomparison and calibration of dose calibrators used in most of nuclear medicine facilities for the determination of the activity of radionuclides administered to patients in specific examinations or therapeutic procedures. A commercial dose calibrator, a set of standard radioactive sources, and syringes, vials and ampoules with radionuclide solutions used in nuclear medicine were utilized in this work. The commercial dose calibrator was calibrated for radionuclide solutions used in nuclear medicine. Simple instrument tests, such as linearity response and variation response with the source volume at a constant source activity concentration were performed. This instrument may be used as a reference system for intercomparison and calibration of other activity meters, as a method of quality control of dose calibrators utilized in nuclear medicine facilities.

Calibration of a large volume argon-41 gas-effluent monitor

International Nuclear Information System (INIS)

Wilson, William E.; Lovas, Thomas A.

1976-01-01

In September of 1975, a large volume Argon-41 sampler was calibrated using a series connected calibration chamber of known sensitivity and a constant flow of activated Argon gas. The calibration included analysis of the effects of flow rate through the large volume sampler and yielded a calibration constant of 2.34 x 10 -8 μc/cm 3 /CPM. (author)

Chaos, Consternation and CALIPSO Calibration: New Strategies for Calibrating the CALIOP 1064 nm Channel

Science.gov (United States)

Vaughan, Mark; Garnier, Anne; Liu, Zhaoyan; Josset, Damien; Hu, Yongxiang; Lee, Kam-Pui; Hunt, William; Vernier, Jean-Paul; Rodier, Sharon; Pelon, Jaques;

CALIBRATING THE JOHNSON-HOLMQUIST CERAMIC MODEL FOR SIC USING CTH

International Nuclear Information System (INIS)

Cazamias, J. U.; Bilyk, S. R.

2009-01-01

The Johnson-Holmquist ceramic material model has been calibrated and successfully applied to numerically simulate ballistic events using the Lagrangian code EPIC. While the majority of the constants are ''physics'' based, two of the constants for the failed material response are calibrated using ballistic experiments conducted on a confined cylindrical ceramic target. The maximum strength of the failed ceramic is calibrated by matching the penetration velocity. The second refers to the equivalent plastic strain at failure under constant pressure and is calibrated using the dwell time. Use of these two constants in the CTH Eulerian hydrocode does not predict the ballistic response. This difference may be due to the phenomenological nature of the model and the different numerical schemes used by the codes. This paper determines the aforementioned material constants for SiC suitable for simulating ballistic events using CTH.

Calibration of NRSF2 Instrument at HFIR

International Nuclear Information System (INIS)

Tang, Fei; Hubbard, Camden R.

2006-01-01

the sample table, 2θ 0 offset, and response of the position sensitive detector; (2) Counting statistics - if the peak profile count is too low, then the peak position derived from fitting a profile and background will have larger error. Therefore, adequate counting statistics and well-defined peaks are always good for precise peak position determination; and (3) Sample - Large grain size materials make it difficult to get enough diffracting grains, contributing to the different profile. With a low number the peak becomes 'spot' and results in inaccuracy in peak position. Texture in the sample can change the effective elastic constants and also affect the peak intensity. Phase and composition inhomogeneity can make it difficult to determine an accurate stress-free d 0 for strain calculation. A partially buried gauge volume due to proximity to the sample surface or buried interface can also shift the peak position. The calibration method presented in this report will address the first two categories of difficulties listed above. The FWHM can be minimized for each sample d-spacing by adjusting the horizontal bending of the monochromator crystal. For the monochromator, the optimum FWHM lies between 70 and 110 degree. This range is selected in order to maintain an approximately equiaxed gauge volume and avoid significant increases in peak breadth for the detectors above and below the horizontal plane. To adequately calibrate the position sensitive detectors, 2θ 0 , and wavelength, a set of high purity reference powders were selected. Since the selected reference powders have define grain size is, the measurement errors from sample grain size and texture can be excluded, although there may still be micro-strain in the powders, which can broaden the reference peak. In this report, the calibration procedure for the NRSF2 instrument will be presented and calibration results for five monochromator settings from HFIR cycle 403 will be presented. The monochromator settings

Optical Comb from a Whispering Gallery Mode Resonator for Spectroscopy and Astronomy Instruments Calibration

Science.gov (United States)

Strekalov, Dmitry V.; Yu, Nam; Thompson, Robert J.

2012-01-01

The most accurate astronomical data is available from space-based observations that are not impeded by the Earth's atmosphere. Such measurements may require spectral samples taken as long as decades apart, with the 1 cm/s velocity precision integrated over a broad wavelength range. This raises the requirements specifically for instruments used in astrophysics research missions -- their stringent wavelength resolution and accuracy must be maintained over years and possibly decades. Therefore, a stable and broadband optical calibration technique compatible with spaceflights becomes essential. The space-based spectroscopic instruments need to be calibrated in situ, which puts forth specific requirements to the calibration sources, mainly concerned with their mass, power consumption, and reliability. A high-precision, high-resolution reference wavelength comb source for astronomical and astrophysics spectroscopic observations has been developed that is deployable in space. The optical comb will be used for wavelength calibrations of spectrographs and will enable Doppler measurements to better than 10 cm/s precision, one hundred times better than the current state-of-the- art.

Data processing and in-flight calibration systems for OMI-EOS-Aura

Science.gov (United States)

van den Oord, G. H. J.; Dobber, M.; van de Vegte, J.; van der Neut, I.; Som de Cerff, W.; Rozemeijer, N. C.; Schenkelaars, V.; ter Linden, M.

2006-08-01

The OMI instrument that flies on the EOS Aura mission was launched in July 2004. OMI is a UV-VIS imaging spectrometer that measures in the 270 - 500 nm wavelength range. OMI provides daily global coverage with high spatial resolution. Every orbit of 100 minutes OMI generates about 0.5 GB of Level 0 data and 1.2 GB of Level 1 data. About half of the Level 1 data consists of in-flight calibration measurements. These data rates make it necessary to automate the process of in-flight calibration. For that purpose two facilities have been developed at KNMI in the Netherlands: the OMI Dutch Processing System (ODPS) and the Trend Monitoring and In-flight Calibration Facility (TMCF). A description of these systems is provided with emphasis on the use for radiometric, spectral and detector calibration and characterization. With the advance of detector technology and the need for higher spatial resolution, data rates will become even higher for future missions. To make effective use of automated systems like the TMCF, it is of paramount importance to integrate the instrument operations concept, the information contained in the Level 1 (meta-)data products and the inflight calibration software and system databases. In this way a robust but also flexible end-to-end system can be developed that serves the needs of the calibration staff, the scientific data users and the processing staff. The way this has been implemented for OMI may serve as an example of a cost-effective and user friendly solution for future missions. The basic system requirements for in-flight calibration are discussed and examples are given how these requirements have been implemented for OMI. Special attention is paid to the aspect of supporting the Level 0 - 1 processing with timely and accurate calibration constants.

Photometric Calibration of the SPRED at the FTU Tokamak

International Nuclear Information System (INIS)

May, M J

1999-01-01

The SPRED spectrometer was photometrically calibrated by using the FTU tokamak plasma and the Grazing Incidence Time Resolving Spectrometer (GRITS) from the Johns Hopkins University [Stratton, Nucl. Fusion, Vol. 24, No. 6, pp. 767-777, 1984]. The photometric calibration of the GRITS spectrometer was transferred to the SPRED [Fonck, R.J., Applied Optics, Vol. 21, No. 12, p. 2115 (1982)] by directly comparing the intensity of bright lines emitted from the FTU tokamak plasma that were simultaneously measured by both spectrometers. The GRITS spectrometer (λ = 10 - 360 (angstrom); Δλ ∼ 0.7 (angstrom)) was photometrically calibrated in the 50 - 360 (angstrom) spectral range at the SURF II synchrotron light source at NIST in Gaithersburg MD in August 1997. The calibration of each SPRED grating was performed separately. These gratings covered the short wavelengths: 100 - 300 (angstrom)(Δλ - 1.4 (angstrom)) and the long wavelengths: 200 - 1800 (angstrom) (Δλ ∼ 7 (angstrom)). This calibration should be accurate until the microchannel plate of the SPRED is exposed to atmospheric pressure. This calibration is similar to the one obtained by Stratton [Stratton, Rev. Sci. Instrum. 57 (8), pp. 204,3 August 1986

Updating the HST/ACS G800L Grism Calibration

Science.gov (United States)

Hathi, Nimish P.; Pirzkal, Norbert; Grogin, Norman A.; Chiaberge, Marco; ACS Team

2018-06-01

We present results from our ongoing work on obtaining newly derived trace and wavelength calibrations of the HST/ACS G800L grism and comparing them to previous set of calibrations. Past calibration efforts were based on 2003 observations. New observations of an emission line Wolf-Rayet star (WR96) were recently taken in HST Cycle 25 (PID: 15401). These observations are used to analyze and measure various grism properties, including wavelength calibration, spectral trace/tilt, length/size of grism orders, and spacing between various grism orders. To account for the field dependence, we observe WR96 at 3 different observing positions over the HST/ACS field of view. The three locations are the center of chip 1, the center of chip 2, and the center of the WFC1A-2K subarray (center of WFC Amp A on chip 1). This new data will help us to evaluate any differences in the G800L grism properties compared to previous calibration data, and to apply improved data analysis techniques to update these old measurements.

In situ calibration of a light source in a sensor device

Science.gov (United States)

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.

Demonstrated Wavelength Portability of Raman Reference Data for Explosives and Chemical Detection

Directory of Open Access Journals (Sweden)

Timothy J. Johnson

2012-01-01

Full Text Available As Raman spectroscopy continues to evolve, questions arise as to the portability of Raman data: dispersive versus Fourier transform, wavelength calibration, intensity calibration, and in particular the frequency of the excitation laser. While concerns about fluorescence arise in the visible or ultraviolet, most modern (portable systems use near-infrared excitation lasers, and many of these are relatively close in wavelength. We have investigated the possibility of porting reference data sets from one NIR wavelength system to another: We have constructed a reference library consisting of 145 spectra, including 20 explosives, as well as sundry other compounds and materials using a 1064 nm spectrometer. These data were used as a reference library to evaluate the same 145 compounds whose experimental spectra were recorded using a second 785 nm spectrometer. In 128 cases of 145 (or 88.3% including 20/20 for the explosives, the compounds were correctly identified with a mean “hit score” of 954 of 1000. Adding in criteria for when to declare a correct match versus when to declare uncertainty, the approach was able to correctly categorize 134 out of 145 spectra, giving a 92.4% accuracy. For the few that were incorrectly identified, either the matched spectra were spectroscopically similar to the target or the 785 nm signal was degraded due to fluorescence. The results indicate that imported data recorded at a different NIR wavelength can be successfully used as reference libraries, but key issues must be addressed: the reference data must be of equal or higher resolution than the resolution of the current sensor, the systems require rigorous wavelength calibration, and wavelength-dependent intensity response should be accounted for in the different systems.

Spectrophotometric calibration system for DECam

Science.gov (United States)

Rheault, J.-P.; DePoy, D. L.; Marshall, J. L.; Prochaska, T.; Allen, R.; Wise, J.; Martin, E.; Williams, P.

2012-09-01

We describe a spectrophotometric calibration system that is being implemented as part of the DES DECam project at the Blanco 4 meter at CTIO. Our calibration system uses a 1nm wide tunable source to measure the instrumental response function of the telescope optics and detector from 300nm up to 1100nm. This calibration will be performed regularly to monitor any change in the transmission function of the telescope during the 5 year survey. The system consists of a monochromator based tunable light source that provides illumination on a dome flat that is monitored by calibrated photodiodes that allow us to measure the telescope throughput as a function of wavelength. Our system has a peak output power of 2 mW, equivalent to a flux of approximately 800 photons/s/pixel on DECam.

SDSS-IV/MaNGA: SPECTROPHOTOMETRIC CALIBRATION TECHNIQUE

Energy Technology Data Exchange (ETDEWEB)

Yan, Renbin; Sánchez-Gallego, José R. [Department of Physics and Astronomy, University of Kentucky, 505 Rose St., Lexington, KY 40506-0057 (United States); Tremonti, Christy; Bershady, Matthew A.; Eigenbrot, Arthur; Wake, David A. [Department of Astronomy, University of Winsconsin-Madison, 475 N. Charter Street, Madison, WI 53706-1582 (United States); Law, David R. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Schlegel, David J. [Physics Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720-8160 (United States); Bundy, Kevin [Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Drory, Niv [McDonald Observatory, Department of Astronomy, University of Texas at Austin, 1 University Station, Austin, TX 78712-0259 (United States); MacDonald, Nicholas [Department of Astronomy, Box 351580, University of Washington, Seattle, WA 98195 (United States); Bizyaev, Dmitry [Apache Point Observatory, P.O. Box 59, sunspot, NM 88349 (United States); Blanc, Guillermo A. [Departamento de Astronomía, Universidad de Chile, Camino el Observatorio 1515, Las Condes, Santiago (Chile); Blanton, Michael R.; Hogg, David W. [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Cherinka, Brian [Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, Ontario M5S 3H4 (Canada); Gunn, James E. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Harding, Paul [Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106 (United States); Sánchez, Sebastian F., E-mail: yanrenbin@uky.edu [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, A.P. 70-264, 04510 Mexico D.F. (Mexico); and others

2016-01-15

Mapping Nearby Galaxies at Apache Point Observatory (MaNGA), one of three core programs in the Sloan Digital Sky Survey-IV, is an integral-field spectroscopic survey of roughly 10,000 nearby galaxies. It employs dithered observations using 17 hexagonal bundles of 2″ fibers to obtain resolved spectroscopy over a wide wavelength range of 3600–10300 Å. To map the internal variations within each galaxy, we need to perform accurate spectral surface photometry, which is to calibrate the specific intensity at every spatial location sampled by each individual aperture element of the integral field unit. The calibration must correct only for the flux loss due to atmospheric throughput and the instrument response, but not for losses due to the finite geometry of the fiber aperture. This requires the use of standard star measurements to strictly separate these two flux loss factors (throughput versus geometry), a difficult challenge with standard single-fiber spectroscopy techniques due to various practical limitations. Therefore, we developed a technique for spectral surface photometry using multiple small fiber-bundles targeting standard stars simultaneously with galaxy observations. We discuss the principles of our approach and how they compare to previous efforts, and we demonstrate the precision and accuracy achieved. MaNGA's relative calibration between the wavelengths of Hα and Hβ has an rms of 1.7%, while that between [N ii] λ6583 and [O ii] λ3727 has an rms of 4.7%. Using extinction-corrected star formation rates and gas-phase metallicities as an illustration, this level of precision guarantees that flux calibration errors will be sub-dominant when estimating these quantities. The absolute calibration is better than 5% for more than 89% of MaNGA's wavelength range.

SDSS-IV/MaNGA: SPECTROPHOTOMETRIC CALIBRATION TECHNIQUE

International Nuclear Information System (INIS)

Yan, Renbin; Sánchez-Gallego, José R.; Tremonti, Christy; Bershady, Matthew A.; Eigenbrot, Arthur; Wake, David A.; Law, David R.; Schlegel, David J.; Bundy, Kevin; Drory, Niv; MacDonald, Nicholas; Bizyaev, Dmitry; Blanc, Guillermo A.; Blanton, Michael R.; Hogg, David W.; Cherinka, Brian; Gunn, James E.; Harding, Paul; Sánchez, Sebastian F.

2016-01-01

Mapping Nearby Galaxies at Apache Point Observatory (MaNGA), one of three core programs in the Sloan Digital Sky Survey-IV, is an integral-field spectroscopic survey of roughly 10,000 nearby galaxies. It employs dithered observations using 17 hexagonal bundles of 2″ fibers to obtain resolved spectroscopy over a wide wavelength range of 3600–10300 Å. To map the internal variations within each galaxy, we need to perform accurate spectral surface photometry, which is to calibrate the specific intensity at every spatial location sampled by each individual aperture element of the integral field unit. The calibration must correct only for the flux loss due to atmospheric throughput and the instrument response, but not for losses due to the finite geometry of the fiber aperture. This requires the use of standard star measurements to strictly separate these two flux loss factors (throughput versus geometry), a difficult challenge with standard single-fiber spectroscopy techniques due to various practical limitations. Therefore, we developed a technique for spectral surface photometry using multiple small fiber-bundles targeting standard stars simultaneously with galaxy observations. We discuss the principles of our approach and how they compare to previous efforts, and we demonstrate the precision and accuracy achieved. MaNGA's relative calibration between the wavelengths of Hα and Hβ has an rms of 1.7%, while that between [N ii] λ6583 and [O ii] λ3727 has an rms of 4.7%. Using extinction-corrected star formation rates and gas-phase metallicities as an illustration, this level of precision guarantees that flux calibration errors will be sub-dominant when estimating these quantities. The absolute calibration is better than 5% for more than 89% of MaNGA's wavelength range

Calibration-free optical chemical sensors

Science.gov (United States)

DeGrandpre, Michael D.

2006-04-11

An apparatus and method for taking absorbance-based chemical measurements are described. In a specific embodiment, an indicator-based pCO2 (partial pressure of CO2) sensor displays sensor-to-sensor reproducibility and measurement stability. These qualities are achieved by: 1) renewing the sensing solution, 2) allowing the sensing solution to reach equilibrium with the analyte, and 3) calculating the response from a ratio of the indicator solution absorbances which are determined relative to a blank solution. Careful solution preparation, wavelength calibration, and stray light rejection also contribute to this calibration-free system. Three pCO2 sensors were calibrated and each had response curves which were essentially identical within the uncertainty of the calibration. Long-term laboratory and field studies showed the response had no drift over extended periods (months). The theoretical response, determined from thermodynamic characterization of the indicator solution, also predicted the observed calibration-free performance.

Calibration and intercomparison methods of dose calibrators used in nuclear medicine facilities

International Nuclear Information System (INIS)

Costa, Alessandro Martins da

1999-01-01

Dose calibrators are used in most of the nuclear medicine facilities to determine the amount of radioactivity administered to a patient in a particular investigation or therapeutic procedure. It is therefore of vital importance that the equipment used presents good performance and is regular;y calibrated at a authorized laboratory. This occurs of adequate quality assurance procedures are carried out. Such quality control tests should be performed daily, other biannually or yearly, testing, for example, its accuracy and precision, the reproducibility and response linearity. In this work a commercial dose calibrator was calibrated with solution of radionuclides used in nuclear medicine. Simple instrument tests, such as response linearity and the response variation of the source volume increase at a constant source activity concentration, were performed. This instrument can now be used as a working standard for calibration of other dose calibrators/ An intercomparison procedure was proposed as a method of quality control of dose calibrators used in nuclear medicine facilities. (author)

Calibration of triaxial fluxgate gradiometer

International Nuclear Information System (INIS)

Vcelak, Jan

2006-01-01

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

Obtaining changes in calibration-coil to seismometer output constants using sine waves

Science.gov (United States)

Ringler, Adam T.; Hutt, Charles R.; Gee, Lind S.; Sandoval, Leo D.; Wilson, David C.

2013-01-01

The midband sensitivity of a broadband seismometer is one of the most commonly used parameters from station metadata. Thus, it is critical for station operators to robustly estimate this quantity with a high degree of accuracy. We develop an in situ method for estimating changes in sensitivity using sine‐wave calibrations, assuming the calibration coil and its drive are stable over time and temperature. This approach has been used in the past for passive instruments (e.g., geophones) but has not been applied, to our knowledge, to derive sensitivities of modern force‐feedback broadband seismometers. We are able to detect changes in sensitivity to well within 1%, and our method is capable of detecting these sensitivity changes using any frequency of sine calibration within the passband of the instrument.

A photon pressure calibrator for the GEO 600 gravitational wave detector

International Nuclear Information System (INIS)

Mossavi, K.; Hewitson, M.; Hild, S.; Seifert, F.; Weiland, U.; Smith, J.R.; Lueck, H.; Grote, H.; Willke, B.; Danzmann, K.

2006-01-01

Interferometer mirror displacement induced by radiation pressure is used to demonstrate an alternative calibration method for the GEO 600 detector. The photon calibrator utilizes an amplitude modulated laser diode with up to 1.4 W output power at a wavelength of 1035 nm. The achieved accuracy of the strain amplitude calibration is dominated by the laser power calibration error, which is in the range of ±4% for the measurements presented in this Letter

HERA-B framework for online calibration and alignment

International Nuclear Information System (INIS)

Hernandez, J.M.; Ressing, D.; Rybnikov, V.; Sanchez, F.; Medinnis, M.; Kreuzer, P.; Schwanke, U.; Amorim, A.

2004-09-01

This paper describes the architecture and implementation of the HERA-B framework for online calibration and alignment. At HERA-B the performance of all trigger levels, including the online reconstruction, strongly depends on using the appropriate calibration and alignment constants, which might change during data taking. A system to monitor, recompute and distribute those constants to online processes has been integrated in the data acquisition and trigger systems. (orig.)

Spectral emissivity of surface blackbody calibrators

DEFF Research Database (Denmark)

Clausen, Sønnik

2007-01-01

The normal spectral emissivity of commercial infrared calibrators is compared with measurements of anodized aluminum samples and grooved aluminum surfaces coated with Pyromark. Measurements performed by FTIR spectroscopy in the wavelength interval from 2 to 20 mu m and at temperatures between 5...

Optimized Spectrometers Characterization Procedure for Near Ground Support of ESA FLEX Observations: Part 1 Spectral Calibration and Characterisation

Directory of Open Access Journals (Sweden)

Laura Mihai

2018-02-01

Full Text Available The paper presents two procedures for the wavelength calibration, in the oxygen telluric absorption spectral bands (O2-A, λc = 687 nm and O2-B, λc = 760.6 nm, of field fixed-point spectrometers used for reflectance and Sun-induced fluorescence measurements. In the first case, Ne and Ar pen-type spectral lamps were employed, while the second approach is based on a double monochromator setup. The double monochromator system was characterized for the estimation of errors associated with different operating configurations. The proposed methods were applied to three Piccolo Doppio-type systems built around two QE Pros and one USB2 + H16355 Ocean Optics spectrometers. The wavelength calibration errors for all the calibrations performed on the three spectrometers are reported and potential methodological improvements discussed. The suggested calibration methods were validated, as the wavelength corrections obtained by both techniques for the QE Pro designed for fluorescence investigations were similar. However, it is recommended that a neon emission line source, as well as an argon or mercury-argon source be used to have a reference wavelength closer to the O2-B feature. The wavelength calibration can then be optimised as close to the O2-B and O2-A features as possible. The monochromator approach could also be used, but that instrument would need to be fully characterized prior to use, and although it may offer a more accurate calibration, as it could be tuned to emit light at the same wavelengths as the absorption features, it would be more time consuming as it is a scanning approach.

Calibrating spectral images using penalized likelihood

NARCIS (Netherlands)

Heijden, van der G.W.A.M.; Glasbey, C.

2003-01-01

A new method is presented for automatic correction of distortions and for spectral calibration (which band corresponds to which wavelength) of spectral images recorded by means of a spectrograph. The method consists of recording a bar-like pattern with an illumination source with spectral bands

Absolute analytical prediction of photonic crystal guided mode resonance wavelengths

DEFF Research Database (Denmark)

Hermannsson, Pétur Gordon; Vannahme, Christoph; Smith, Cameron

2014-01-01

numerically with methods such as rigorous coupled wave analysis. Here it is demonstrated how the absolute resonance wavelengths of such structures can be predicted by analytically modeling them as slab waveguides in which the propagation constant is determined by a phase matching condition. The model...... is experimentally verified to be capable of predicting the absolute resonance wavelengths to an accuracy of within 0.75 nm, as well as resonance wavelength shifts due to changes in cladding index within an accuracy of 0.45 nm across the visible wavelength regime in the case where material dispersion is taken...

Comparison of Two Methodologies for Calibrating Satellite Instruments in the Visible and Near-Infrared

Science.gov (United States)

Barnes, Robert A.; Brown, Steven W.; Lykke, Keith R.; Guenther, Bruce; Butler, James J.; Schwarting, Thomas; Turpie, Kevin; Moyer, David; DeLuccia, Frank; Moeller, Christopher

2015-01-01

Traditionally, satellite instruments that measure Earth-reflected solar radiation in the visible and near infrared wavelength regions have been calibrated for radiance responsivity in a two-step method. In the first step, the relative spectral response (RSR) of the instrument is determined using a nearly monochromatic light source such as a lamp-illuminated monochromator. These sources do not typically fill the field-of-view of the instrument nor act as calibrated sources of light. Consequently, they only provide a relative (not absolute) spectral response for the instrument. In the second step, the instrument views a calibrated source of broadband light, such as a lamp-illuminated integrating sphere. The RSR and the sphere absolute spectral radiance are combined to determine the absolute spectral radiance responsivity (ASR) of the instrument. More recently, a full-aperture absolute calibration approach using widely tunable monochromatic lasers has been developed. Using these sources, the ASR of an instrument can be determined in a single step on a wavelength-by-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 lamp-illuminated integrating spheres. In this work, the traditional broadband source-based calibration of the Suomi National Preparatory Project (SNPP) Visible Infrared Imaging Radiometer Suite (VIIRS) sensor is compared with the laser-based calibration of the sensor. Finally, the impact of the new full-aperture laser-based calibration approach on the on-orbit performance of the sensor is considered.

Development and operation of a high-throughput accurate-wavelength lens-based spectrometer

Energy Technology Data Exchange (ETDEWEB)

Bell, Ronald E., E-mail: rbell@pppl.gov [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

2014-11-15

A high-throughput spectrometer for the 400–820 nm wavelength range has been developed for charge exchange recombination spectroscopy or general spectroscopy. A large 2160 mm{sup −1} grating is matched with fast f/1.8 200 mm lenses, which provide stigmatic imaging. A precision optical encoder measures the grating angle with an accuracy ≤0.075 arc sec. A high quantum efficiency low-etaloning CCD detector allows operation at longer wavelengths. A patch panel allows input fibers to interface with interchangeable fiber holders that attach to a kinematic mount at the entrance slit. Computer-controlled hardware allows automated control of wavelength, timing, f-number, automated data collection, and wavelength calibration.

Free-space wavelength-multiplexed optical scanner demonstration.

Science.gov (United States)

Yaqoob, Zahid; Riza, Nabeel A

2002-09-10

Experimental demonstration of a no-moving-parts free-space wavelength-multiplexed optical scanner (W-MOS) is presented. With fast tunable lasers or optical filters and planar wavelength dispersive elements such as diffraction gratings, this microsecond-speed scanner enables large several-centimeter apertures for subdegree angular scans. The proposed W-MOS design incorporates a unique optical amplifier and variable optical attenuator combination that enables the calibration and modulation of the scanner response, leading to any desired scanned laser beam power shaping. The experimental setup uses a tunable laser centered at 1560 nm and a 600-grooves/mm blazed reflection grating to accomplish an angular scan of 12.92 degrees as the source is tuned over an 80-nm bandwidth. The values for calculated maximum optical beam divergance, required wavelength resolution, beam-pointing accuracy, and measured scanner insertion loss are 1.076 mrad, 0.172 nm, 0.06 mrad, and 4.88 dB, respectively.

Observation of magnon-phonon interaction at short wavelengths

International Nuclear Information System (INIS)

Dolling, G.; Cowley, R.A.

1966-01-01

Measurements have been made of the magnon and phonon dispersion relations in uranium dioxide at 9 o K. These measurements provide evidence of a strong interaction between the magnon and phonon excitations and enable a value to be deduced for the coupling constant. The interaction of long-wavelength magnons in ferromagnetic materials has been studied previously with ultrasonic techniques; however, inelastic scattering of slow neutrons enables both the magnon and phonon dispersion relations to be determined for short wavelengths. In those magnetic materials which have been studied by earlier workers, the magnons and phonons either interacted with one another very weakly or else their frequencies were very different. The results could then be understood without introducing any magnon-phonon interaction. In this note we report measurements of both the magnon and the phonon spectra of antiferromagnetic uranium dioxide, which lead to a magnon-phonon coupling constant of 9.6 ± 1.6 o K. Since the Neel temperature is 30.8 o K, this coupling constant is of a similar magnitude to the direct magnetic interactions. (author)

Solid laboratory calibration of a nonimaging spectroradiometer.

Science.gov (United States)

Schaepman, M E; Dangel, S

2000-07-20

Field-based nonimaging spectroradiometers are often used in vicarious calibration experiments for airborne or spaceborne imaging spectrometers. The calibration uncertainties associated with these ground measurements contribute substantially to the overall modeling error in radiance- or reflectance-based vicarious calibration experiments. Because of limitations in the radiometric stability of compact field spectroradiometers, vicarious calibration experiments are based primarily on reflectance measurements rather than on radiance measurements. To characterize the overall uncertainty of radiance-based approaches and assess the sources of uncertainty, we carried out a full laboratory calibration. This laboratory calibration of a nonimaging spectroradiometer is based on a measurement plan targeted at achieving a calibration. The individual calibration steps include characterization of the signal-to-noise ratio, the noise equivalent signal, the dark current, the wavelength calibration, the spectral sampling interval, the nonlinearity, directional and positional effects, the spectral scattering, the field of view, the polarization, the size-of-source effects, and the temperature dependence of a particular instrument. The traceability of the radiance calibration is established to a secondary National Institute of Standards and Technology calibration standard by use of a 95% confidence interval and results in an uncertainty of less than ?7.1% for all spectroradiometer bands.

Compact blackbody calibration sources for in-flight calibration of spaceborne infrared instruments

Science.gov (United States)

Scheiding, S.; Driescher, H.; Walter, I.; Hanbuch, K.; Paul, M.; Hartmann, M.; Scheiding, M.

2017-11-01

High-emissivity blackbodies are mandatory as calibration sources in infrared radiometers. Besides the requirements on the high spectral emissivity and low reflectance, constraints regarding energy consumption, installation space and mass must be considered during instrument design. Cavity radiators provide an outstanding spectral emissivity to the price of installation space and mass of the calibration source. Surface radiation sources are mainly limited by the spectral emissivity of the functional coating and the homogeneity of the temperature distribution. The effective emissivity of a "black" surface can be optimized, by structuring the substrate with the aim to enlarge the ratio of the surface to its projection. Based on the experiences of the Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) calibration source MBB3, the results of the surface structuring on the effective emissivity are described analytically and compared to the experimental performance. Different geometries are analyzed and the production methods are discussed. The high-emissivity temperature calibration source features values of 0.99 for wavelength from 5 μm to 10 μm and emissivity larger than 0.95 for the spectral range from 10 μm to 40 μm.

A fundamental parameter-based calibration model for an intrinsic germanium X-ray fluorescence spectrometer

International Nuclear Information System (INIS)

Christensen, L.H.; Pind, N.

1982-01-01

A matrix-independent fundamental parameter-based calibration model for an energy-dispersive X-ray fluorescence spectrometer has been developed. This model, which is part of a fundamental parameter approach quantification method, accounts for both the excitation and detection probability. For each secondary target a number of relative calibration constants are calculated on the basis of knowledge of the irradiation geometry, the detector specifications, and tabulated fundamental physical parameters. The absolute calibration of the spectrometer is performed by measuring one pure element standard per secondary target. For sample systems where all elements can be analyzed by means of the same secondary target the absolute calibration constant can be determined during the iterative solution of the basic equation. Calculated and experimentally determined relative calibration constants agree to within 5-10% of each other and so do the results obtained from the analysis of an NBS certified alloy using the two sets of constants. (orig.)

Calibration of UV instruments and limitations on accuracy

International Nuclear Information System (INIS)

Clare, J.F.; Hamlin, J.D.

1993-01-01

Instruments measuring UV radiation may be classified as either spectrometers or broadband monitors; whilst the former determine irradiance as a function of wavelength the latter measure a summation of spectral irradiance weighted by some instrument response function which may be designed to approximate a desired action spectrum. For both classes a proper calibration requires the determination of the instrument's absolute spectral responsivity across the relevant wave-band together with an adequate determination of the wavelengths involved. (author). 7 refs

From laboratory to the sky: Th-Ar wavelength standards for the cryogenic infrared echelle spectrograph (CRIRES)

Energy Technology Data Exchange (ETDEWEB)

Kerber, Florian; Bristow, Paul [European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching (Germany); Nave, Gillian; Sansonetti, Craig J [National Institute of Standards and Technology, Gaithersburg, MD (United States)], E-mail: fkerber@eso.org, E-mail: gillian.nave@nist.gov, E-mail: craig.sansonetti@nist.gov, E-mail: bristowp@eso.org

2009-05-15

We report on the collaborative effort of the European Southern Observatory (ESO) and the National Institute of Standards and Technology (NIST) to establish-through laboratory measurements-wavelength standards in the near-infrared (IR) emission line spectrum of a low current Th-Ar hollow cathode lamp. These standards are now routinely used for the wavelength calibration of the cryogenic infrared echelle spectrograph (CRIRES) operated at one of the unit telescopes of the very large telescope (VLT) at ESO's La Silla Paranal Observatory in Chile. The availability of highly accurate wavelength standards from a commercially available calibration source permits a shift to a new operational paradigm for high-resolution IR spectroscopy. Wavelength calibration no longer has to rely on atmospheric features but can make use of laboratory traceable reference data as is normally done in the ultraviolet and visible regions. This opens the door for more quantitative spectroscopic work in the near-IR. To illustrate the potential impact of this development, we briefly review the current state of affairs in IR astronomy and its projected future. With the advent of the next generation of extremely large ground-based telescopes the IR region will become the most powerful window on the universe within the next 10-15 years. We conclude with a short outlook on the contribution atomic physics can make to this evolution.

Calibration of EFOSC2 Broadband Linear Imaging Polarimetry

Science.gov (United States)

Wiersema, K.; Higgins, A. B.; Covino, S.; Starling, R. L. C.

2018-03-01

The European Southern Observatory Faint Object Spectrograph and Camera v2 is one of the workhorse instruments on ESO's New Technology Telescope, and is one of the most popular instruments at La Silla observatory. It is mounted at a Nasmyth focus, and therefore exhibits strong, wavelength and pointing-direction-dependent instrumental polarisation. In this document, we describe our efforts to calibrate the broadband imaging polarimetry mode, and provide a calibration for broadband B, V, and R filters to a level that satisfies most use cases (i.e. polarimetric calibration uncertainty 0.1%). We make our calibration codes public. This calibration effort can be used to enhance the yield of future polarimetric programmes with the European Southern Observatory Faint Object Spectrograph and Camera v2, by allowing good calibration with a greatly reduced number of standard star observations. Similarly, our calibration model can be combined with archival calibration observations to post-process data taken in past years, to form the European Southern Observatory Faint Object Spectrograph and Camera v2 legacy archive with substantial scientific potential.

Rapid and accurate determination of Stern-Volmer quenching constants

International Nuclear Information System (INIS)

Goodpaster, John V.; McGuffin, Victoria L.

1999-01-01

In this work, a novel system has been designed, characterized, and validated for the determination of fluorescence quenching constants. Capillary flow injection methods are used to automate the preparation and mixing of the fluorophore and quencher solutions. Because of the small diameter of the capillary (75-200 μm), fluorescence measurements can be made without corrections for primary and secondary absorbance effects. The fluorescence spectrometer is equipped with a charge-coupled device (CCD) that has a detection limit of 3.0x10 -9 M (2.3 ppb) and a linear dynamic range of 10 5 for integration times of 0.01-10 s. This spectrometer has a 300 nm spectral range with 1 nm resolution, allowing the fluorescence quenching constants to be calculated at single wavelengths or over integrated wavelength ranges. This system was validated by comparison to traditional methods for the determination of Stern-Volmer constants for alternant and nonalternant polycyclic aromatic hydrocarbons with nitromethane and triethylamine. (c) 2000 Society for Applied Spectroscopy

DECal: A Spectrophotometric Calibration System For DECam.

Science.gov (United States)

Rheault, Jean-Philippe; DePoy, D. L.; Marshall, J. L.; Prochaska, T.; Allen, R.; Wise, J.; Martin, E.

2012-01-01

We present preliminary results for a spectrophotometric calibration system that is being implemented as part of the DES DECam project at the Blanco 4 meter at CTIO. Our calibration system uses a 2nm wide tunable source to measure the instrumental response function of the telescope from 300nm up to 1100nm. This calibration will be performed regularly to monitor any change in the transmission function. The system consists of a monochromator based tunable light source that provides illumination on a dome flat that is monitored by calibrated photodiodes and allow us to measure the throughput as a function of wavelength. Our system has an output power of 2 mW, equivalent to a flux of approximately 800 photons/s/pixel on DECam. Preliminary results of the measure of the throughput of the telescope will be presented.

Nitrogen dioxide and kerosene-flame soot calibration of photoacoustic instruments for measurement of light absorption by aerosols

International Nuclear Information System (INIS)

Arnott, W. Patrick; Moosmu''ller, Hans; Walker, John W.

2000-01-01

A nitrogen dioxide calibration method is developed to evaluate the theoretical calibration for a photoacoustic instrument used to measure light absorption by atmospheric aerosols at a laser wavelength of 532.0 nm. This method uses high concentrations of nitrogen dioxide so that both a simple extinction and the photoacoustically obtained absorption measurement may be performed simultaneously. Since Rayleigh scattering is much less than absorption for the gas, the agreement between the extinction and absorption coefficients can be used to evaluate the theoretical calibration, so that the laser gas spectra are not needed. Photoacoustic theory is developed to account for strong absorption of the laser beam power in passage through the resonator. Findings are that the photoacoustic absorption based on heat-balance theory for the instrument compares well with absorption inferred from the extinction measurement, and that both are well within values represented by published spectra of nitrogen dioxide. Photodissociation of nitrogen dioxide limits the calibration method to wavelengths longer than 398 nm. Extinction and absorption at 532 and 1047 nm were measured for kerosene-flame soot to evaluate the calibration method, and the single scattering albedo was found to be 0.31 and 0.20 at these wavelengths, respectively

Accurate spring constant calibration for very stiff atomic force microscopy cantilevers

Energy Technology Data Exchange (ETDEWEB)

Grutzik, Scott J.; Zehnder, Alan T. [Field of Theoretical and Applied Mechanics, Cornell University, Ithaca, New York 14853 (United States); Gates, Richard S.; Gerbig, Yvonne B.; Smith, Douglas T.; Cook, Robert F. [Nanomechanical Properties Group, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

2013-11-15

There are many atomic force microscopy (AFM) applications that rely on quantifying the force between the AFM cantilever tip and the sample. The AFM does not explicitly measure force, however, so in such cases knowledge of the cantilever stiffness is required. In most cases, the forces of interest are very small, thus compliant cantilevers are used. A number of methods have been developed that are well suited to measuring low stiffness values. However, in some cases a cantilever with much greater stiffness is required. Thus, a direct, traceable method for calibrating very stiff (approximately 200 N/m) cantilevers is presented here. The method uses an instrumented and calibrated nanoindenter to determine the stiffness of a reference cantilever. This reference cantilever is then used to measure the stiffness of a number of AFM test cantilevers. This method is shown to have much smaller uncertainty than previously proposed methods. An example application to fracture testing of nanoscale silicon beam specimens is included.

Accurate spring constant calibration for very stiff atomic force microscopy cantilevers

International Nuclear Information System (INIS)

Grutzik, Scott J.; Zehnder, Alan T.; Gates, Richard S.; Gerbig, Yvonne B.; Smith, Douglas T.; Cook, Robert F.

2013-01-01

There are many atomic force microscopy (AFM) applications that rely on quantifying the force between the AFM cantilever tip and the sample. The AFM does not explicitly measure force, however, so in such cases knowledge of the cantilever stiffness is required. In most cases, the forces of interest are very small, thus compliant cantilevers are used. A number of methods have been developed that are well suited to measuring low stiffness values. However, in some cases a cantilever with much greater stiffness is required. Thus, a direct, traceable method for calibrating very stiff (approximately 200 N/m) cantilevers is presented here. The method uses an instrumented and calibrated nanoindenter to determine the stiffness of a reference cantilever. This reference cantilever is then used to measure the stiffness of a number of AFM test cantilevers. This method is shown to have much smaller uncertainty than previously proposed methods. An example application to fracture testing of nanoscale silicon beam specimens is included

Self-calibrating interferometer

International Nuclear Information System (INIS)

Nussmeier, T.A.

1982-01-01

A self-calibrating interferometer is disclosed which forms therein a pair of Michelson interferometers with one beam length of each Michelson interferometer being controlled by a common phase shifter. The transfer function measured from the phase shifter to either of a pair of detectors is sinusoidal with a full cycle for each half wavelength of phase shifter travel. The phase difference between these two sinusoidal detector outputs represents the optical phase difference between a path of known distance and a path of unknown distance

New indicator for optimal preprocessing and wavelength selection of near-infrared spectra

NARCIS (Netherlands)

Skibsted, E. T. S.; Boelens, H. F. M.; Westerhuis, J. A.; Witte, D. T.; Smilde, A. K.

2004-01-01

Preprocessing of near-infrared spectra to remove unwanted, i.e., non-related spectral variation and selection of informative wavelengths is considered to be a crucial step prior to the construction of a quantitative calibration model. The standard methodology when comparing various preprocessing

A quasi-online distributed data processing on WAN: the ATLAS muon calibration system

CERN Document Server

De Salvo, A; The ATLAS collaboration

2013-01-01

In the Atlas experiment, the calibration of the precision tracking chambers of the muon detector is very demanding, since the rate of muon tracks required to get a complete calibration in homogeneous conditions and to feed prompt reconstruction with fresh constants is very high (several hundreds Hz for 8-10 hours runs). The calculation of calibration constants is highly CPU consuming. In order to fulfill the requirement of completing the cycle and having the final constants available within 24 hours, distributed resources at Tier-2 centers have been allocated. The best place to get muon tracks suitable for detector calibration is the second level trigger, where the pre-selection of data sitting in a limited region by the first level trigger via the Region of Interest mechanism allows selecting all the hits from a single track in a limited region of the detector. Online data extraction allows calibration data collection without performing special runs. Small event pseudo-fragments (about 0.5 kB) built at the m...

Carbon dioxide on the satellites of Saturn: Results from the Cassini VIMS investigation and revisions to the VIMS wavelength scale

Science.gov (United States)

Cruikshank, D.P.; Meyer, A.W.; Brown, R.H.; Clark, R.N.; Jaumann, R.; Stephan, K.; Hibbitts, C.A.; Sandford, S.A.; Mastrapa, R.M.E.; Filacchione, G.; Ore, C.M.D.; Nicholson, P.D.; Buratti, B.J.; McCord, T.B.; Nelson, R.M.; Dalton, J.B.; Baines, K.H.; Matson, D.L.

2010-01-01

Several of the icy satellites of Saturn show the spectroscopic signature of the asymmetric stretching mode of C-O in carbon dioxide (CO2) at or near the nominal solid-phase laboratory wavelength of 4.2675 ??m (2343.3 cm-1), discovered with the Visible-Infrared Mapping Spectrometer (VIMS) on the Cassini spacecraft. We report here on an analysis of the variation in wavelength and width of the CO2 absorption band in the spectra of Phoebe, Iapetus, Hyperion, and Dione. Comparisons are made to laboratory spectra of pure CO2, CO2 clathrates, ternary mixtures of CO2 with other volatiles, implanted and adsorbed CO2 in non-volatile materials, and ab initio theoretical calculations of CO2 * nH2O. At the wavelength resolution of VIMS, the CO2 on Phoebe is indistinguishable from pure CO2 ice (each molecule's nearby neighbors are also CO2) or type II clathrate of CO2 in H2O. In contrast, the CO2 band on Iapetus, Hyperion, and Dione is shifted to shorter wavelengths (typically ???4.255 ??m (???2350.2 cm-1)) and broadened. These wavelengths are characteristic of complexes of CO2 with different near-neighbor molecules that are encountered in other volatile mixtures such as with H2O and CH3OH, and non-volatile host materials like silicates, some clays, and zeolites. We suggest that Phoebe's CO2 is native to the body as part of the initial inventory of condensates and now exposed on the surface, while CO2 on the other three satellites results at least in part from particle or UV irradiation of native H2O plus a source of C, implantation or accretion from external sources, or redistribution of native CO2 from the interior. The analysis presented here depends on an accurate VIMS wavelength scale. In preparation for this work, the baseline wavelength calibration for the Cassini VIMS was found to be distorted around 4.3 ??m, apparently as a consequence of telluric CO2 gas absorption in the pre-launch calibration. The effect can be reproduced by convolving a sequence of model detector

Wavelengths, energy levels and hyperfine structure of Mn II and Sc II.

Science.gov (United States)

Nave, Gillian; Pickering, Juliet C.; Townley-Smith, Keeley I. M.; Hala, .

2015-08-01

For many decades, the Atomic Spectroscopy Groups at the National Institute of Standards and Technology (NIST) and Imperial College London (ICL) have measured atomic data of astronomical interest. Our spectrometers include Fourier transform (FT) spectrometers at NIST and ICL covering the region 1350 Å to 5.5 μm and a 10.7-m grating spectrometer at NIST covering wavelengths from 300 - 5000 Å. Sources for these spectra include high-current continuous and pulsed hollow cathode (HCL) lamps, Penning discharges, and sliding spark discharges. Recent work has focused on the measurement and analysis of wavelengths, energy levels, and hyperfine structure (HFS) constants for iron-group elements. The analysis of FT spectra of Cr I, Mn I, and Mn II is being led by ICL and is described in a companion poster [1]. Current work being led by NIST includes the analysis of HFS in Mn II, analysis of Mn II in the vacuum ultraviolet, and a comprehensive analysis of Sc II.Comprehensive HFS constants for Mn II are needed for the interpretation of stellar spectra and incorrect abundances may be obtained when HFS is omitted. Holt et al. [2] have measured HFS constants for 59 levels of Mn II using laser spectroscopy. We used FT spectra of Mn/Ni and Mn/Cu HCLs covering wavelength ranges from 1350 Å to 5.4 μm to confirm 26 of the A constants of Holt et al. and obtain values for roughly 40 additional levels. We aim to obtain HFS constants for the majority of lines showing significant HFS that are observed in chemically-peculiar stars.Spectra of Sc HCLs have been recorded from 1800 - 6700 Å using a vacuum ultraviolet FT spectrometer at NIST. Additional measurements to cover wavelengths above 6700 Å and below 1800 Å are in progress. The spectra are being analyzed by NIST and Alighar Muslim University, India in order to derive improved wavelengths, energy levels, and hyperfine structure parameters.This work was partially supported by NASA, the STFC and PPARC (UK), the Royal Society of the UK

Determination of human albumin in serum and urine samples by constant-energy synchronous fluorescence method.

Science.gov (United States)

Madrakian, Tayyebeh; Bagheri, Habibollah; Afkhami, Abbas

2015-08-01

A sensitive spectrofluorimetric method using constant-energy synchronous fluorescence technique is proposed for the determination of human albumin without separation. In this method, no reagent was used for enhancement of the fluorescence signal of albumin in the solution. Effects of some parameters, such as energy difference between excitation and emission monochromators (ΔE), emission and excitation slit widths and scan rate of wavelength were studied and the optimum conditions were established. For this purpose factorial design and response surface method were employed for optimization of the effective parameters on the fluorescence signal. The results showed that the scan rate of the wavelength has no significant effect on the analytical signal. The calibration curve was linear in the range 0.1-220.0 µg mL(-1) of albumin with a detection limit of 7.0 × 10(-3)  µg mL(-1). The relative standard deviations (RSD) for six replicate measurements of albumin were calculated as 2.2%, 1.7% and 1.3% for 0.5, 10.0 and 100.0 µg mL(-1) albumin, respectively. Furthermore the proposed method has been employed for the determination of albumin in human serum and urine samples. Copyright © 2014 John Wiley & Sons, Ltd.

Temperature and current coefficients of lasing wavelength in tunable diode laser spectroscopy.

Science.gov (United States)

Fukuda, M; Mishima, T; Nakayama, N; Masuda, T

2010-08-01

The factors determining temperature and current coefficients of lasing wavelength are investigated and discussed under monitoring CO(2)-gas absorption spectra. The diffusion rate of Joule heating at the active layer to the surrounding region is observed by monitoring the change in the junction voltage, which is a function of temperature and the wavelength (frequency) deviation under sinusoidal current modulation. Based on the experimental results, the time interval of monitoring the wavelength after changing the ambient temperature or injected current (scanning rate) has to be constant at least to eliminate the monitoring error induced by the deviation of lasing wavelength, though the temperature and current coefficients of lasing wavelength differ with the rate.

Calibration of a spinner anemometer for yaw misalignment measurements

DEFF Research Database (Denmark)

Friis Pedersen, Troels; Demurtas, Giorgio; Zahle, Frederik

2015-01-01

constant, k1, mainly affects the measurement of wind speed. The ratio between the two constants, kα = k2/k1, however, only affects the measurement of flow angles. The calibration of kα is thus a basic calibration of the spinner anemometer. Theoretical background for the non-linear calibration is derived......The spinner anemometer is an instrument for yaw misalignment measurements without the drawbacks of instruments mounted on the nacelle top. The spinner anemometer uses a non-linear conversion algorithm that converts the measured wind speeds by three sonic sensors on the spinner to horizontal wind...... from the generic spinner anemometer conversion algorithm. Five different methods were evaluated for calibration of a spinner anemometer on a 500 kW wind turbine. The first three methods used rotor yaw direction as reference angular, while the wind turbine, was yawed in and out of the wind. The fourth...

Novel Real-time Calibration and Alignment Procedure for LHCb Run II

CERN Multimedia

Prouve, Claire

2016-01-01

In order to achieve optimal detector performance the LHCb experiment has introduced a novel real-time detector alignment and calibration strategy for Run II of the LHC. For the alignment tasks, data is collected and processed at the beginning of each fill while the calibrations are performed for each run. This real time alignment and calibration allows the same constants being used in both the online and offline reconstruction, thus improving the correlation between triggered and offline selected events. Additionally the newly computed alignment and calibration constants can be instantly used in the trigger, making it more efficient. The online alignment and calibration of the RICH detectors also enable the use of hadronic particle identification in the trigger. The computing time constraints are met through the use of a new dedicated framework using the multi-core farm infrastructure for the LHCb trigger. An overview of all alignment and calibration tasks is presented and their performance is shown.

Permanently calibrated interpolating time counter

International Nuclear Information System (INIS)

Jachna, Z; Szplet, R; Kwiatkowski, P; Różyc, K

2015-01-01

We propose a new architecture of an integrated time interval counter that provides its permanent calibration in the background. Time interval measurement and the calibration procedure are based on the use of a two-stage interpolation method and parallel processing of measurement and calibration data. The parallel processing is achieved by a doubling of two-stage interpolators in measurement channels of the counter, and by an appropriate extension of control logic. Such modification allows the updating of transfer characteristics of interpolators without the need to break a theoretically infinite measurement session. We describe the principle of permanent calibration, its implementation and influence on the quality of the counter. The precision of the presented counter is kept at a constant level (below 20 ps) despite significant changes in the ambient temperature (from −10 to 60 °C), which can cause a sevenfold decrease in the precision of the counter with a traditional calibration procedure. (paper)

Providing radiometric traceability for the calibration home base of DLR by PTB

Energy Technology Data Exchange (ETDEWEB)

Taubert, D. R.; Hollandt, J.; Sperfeld, P.; Pape, S.; Hoepe, A.; Hauer, K.-O. [Physikalisch-Technische Bundesanstalt, Braunschweig und Berlin, 10587 Berlin (Germany); Gege, P.; Schwarzmaier, T.; Lenhard, K.; Baumgartner, A. [Deutsches Zentrum fuer Luft- und Raumfahrt, Institut fuer Methodik der Fernerkundung, 82234 Oberpfaffenhofen (Germany)

2013-05-10

A dedicated calibration technique was applied for the calibration of the spectral radiance transfer standard (RASTA) of the German Aerospace Center (DLR) at the Physikalisch-Technische Bundesanstalt (PTB), consisting of two independent but complementing calibration procedures to provide redundancy and smallest possible calibration uncertainties. Procedure I included two calibration steps: In a first step the optical radiation source of RASTA, an FEL lamp, was calibrated in terms of its spectral irradiance E{sub {lambda}}({lambda}) in the wavelength range from 350 nm to 2400 nm using the PTB Spectral Irradiance Calibration Equipment (SPICE), while in a second step the spectral radiance factor {beta}{sub 0 Degree-Sign :45 Degree-Sign }({lambda}) of the RASTA reflection standard was calibrated in a 0 Degree-Sign :45 Degree-Sign -viewing geometry in the wavelength range from 350 nm to 1700 nm at the robot-based gonioreflectometer facility of PTB. The achieved relative standard uncertainties (k= 1) range from 0.6 % to 3.2 % and 0.1 % to 0.6 % respectively. Procedure II was completely independent from procedure I and allowed to cover the entire spectral range of RASTA from 350 nm to 2500 nm. In the second procedure, the 0 Degree-Sign :45 Degree-Sign -viewing geometry spectral radiance L{sub {lambda},0 Degree-Sign :45 Degree-Sign }({lambda}) of RASTA was directly calibrated at the Spectral Radiance Comparator Facility (SRCF) of PTB. The relative uncertainties for this calibration procedure range from 0.8 % in the visible up to 7.5 % at 2500 nm (k= 1). In the overlapping spectral range of both calibration procedures the calculated spectral radiance L{sub {lambda},0 Degree-Sign :45 Degree-Sign ,calc}({lambda}) from procedure I is in good agreement with the direct measurement of procedure II, i.e. well within the combined expanded uncertainties (k= 2) of both procedures.

Noncontact simultaneous dual wavelength photoplethysmography: A further step toward noncontact pulse oximetry

International Nuclear Information System (INIS)

Humphreys, Kenneth; Ward, Tomas; Markham, Charles

2007-01-01

We present a camera-based device capable of capturing two photoplethysmographic (PPG) signals at two different wavelengths simultaneously, in a remote noncontact manner. The system comprises a complementary metal-oxide semiconductor camera and dual wavelength array of light emitting diodes (760 and 880 nm). By alternately illuminating a region of tissue with each wavelength of light, and detecting the backscattered photons with the camera at a rate of 16 frames/wavelength s, two multiplexed PPG wave forms are simultaneously captured. This process is the basis of pulse oximetry, and we describe how, with the inclusion of a calibration procedure, this system could be used as a noncontact pulse oximeter to measure arterial oxygen saturation (S p O 2 ) remotely. Results from an experiment on ten subjects, exhibiting normal S p O 2 readings, that demonstrate the instrument's ability to capture signals from a range of subjects under realistic lighting and environmental conditions are presented. We compare the signals captured by the noncontact system to a conventional PPG signal captured concurrently from a finger, and show by means of a J. Bland and D. Altman [Lancet 327, 307 (1986); Statistician 32, 307 (1983)] test, the noncontact device to be comparable to a contact device as a monitor of heart rate. We highlight some considerations that should be made when using camera-based ''integrative'' sampling methods and demonstrate through simulation, the suitability of the captured PPG signals for application of existing pulse oximetry calibration procedures

Noncontact simultaneous dual wavelength photoplethysmography: A further step toward noncontact pulse oximetry

Science.gov (United States)

Humphreys, Kenneth; Ward, Tomas; Markham, Charles

2007-04-01

We present a camera-based device capable of capturing two photoplethysmographic (PPG) signals at two different wavelengths simultaneously, in a remote noncontact manner. The system comprises a complementary metal-oxide semiconductor camera and dual wavelength array of light emitting diodes (760 and 880nm). By alternately illuminating a region of tissue with each wavelength of light, and detecting the backscattered photons with the camera at a rate of 16frames/wavelengths, two multiplexed PPG wave forms are simultaneously captured. This process is the basis of pulse oximetry, and we describe how, with the inclusion of a calibration procedure, this system could be used as a noncontact pulse oximeter to measure arterial oxygen saturation (SpO2) remotely. Results from an experiment on ten subjects, exhibiting normal SpO2 readings, that demonstrate the instrument's ability to capture signals from a range of subjects under realistic lighting and environmental conditions are presented. We compare the signals captured by the noncontact system to a conventional PPG signal captured concurrently from a finger, and show by means of a J. Bland and D. Altman [Lancet 327, 307 (1986); Statistician 32, 307 (1983)] test, the noncontact device to be comparable to a contact device as a monitor of heart rate. We highlight some considerations that should be made when using camera-based "integrative" sampling methods and demonstrate through simulation, the suitability of the captured PPG signals for application of existing pulse oximetry calibration procedures.

Colorimetric Determination of the Iron(III)-Thiocyanate Reaction Equilibrium Constant with Calibration and Equilibrium Solutions Prepared in a Cuvette by Sequential Additions of One Reagent to the Other

Science.gov (United States)

Nyasulu, Frazier; Barlag, Rebecca

2011-01-01

The well-known colorimetric determination of the equilibrium constant of the iron(III-thiocyanate complex is simplified by preparing solutions in a cuvette. For the calibration plot, 0.10 mL increments of 0.00100 M KSCN are added to 4.00 mL of 0.200 M Fe(NO[subscript 3])[subscript 3], and for the equilibrium solutions, 0.50 mL increments of…

Method for accurate determination of dissociation constants of optical ratiometric systems: chemical probes, genetically encoded sensors, and interacting molecules.

Science.gov (United States)

Pomorski, Adam; Kochańczyk, Tomasz; Miłoch, Anna; Krężel, Artur

2013-12-03

Ratiometric chemical probes and genetically encoded sensors are of high interest for both analytical chemists and molecular biologists. Their high sensitivity toward the target ligand and ability to obtain quantitative results without a known sensor concentration have made them a very useful tool in both in vitro and in vivo assays. Although ratiometric sensors are widely used in many applications, their successful and accurate usage depends on how they are characterized in terms of sensing target molecules. The most important feature of probes and sensors besides their optical parameters is an affinity constant toward analyzed molecules. The literature shows that different analytical approaches are used to determine the stability constants, with the ratio approach being most popular. However, oversimplification and lack of attention to detail results in inaccurate determination of stability constants, which in turn affects the results obtained using these sensors. Here, we present a new method where ratio signal is calibrated for borderline values of intensities of both wavelengths, instead of borderline ratio values that generate errors in many studies. At the same time, the equation takes into account the cooperativity factor or fluorescence artifacts and therefore can be used to characterize systems with various stoichiometries and experimental conditions. Accurate determination of stability constants is demonstrated utilizing four known optical ratiometric probes and sensors, together with a discussion regarding other, currently used methods.

Systematic error in the precision measurement of the mean wavelength of a nearly monochromatic neutron beam due to geometric errors

Energy Technology Data Exchange (ETDEWEB)

Coakley, K.J., E-mail: kevin.coakley@nist.go [National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305 (United States); Dewey, M.S. [National Institute of Standards and Technology, Gaithersburg, MD (United States); Yue, A.T. [University of Tennessee, Knoxville, TN (United States); Laptev, A.B. [Tulane University, New Orleans, LA (United States)

2009-12-11

Many experiments at neutron scattering facilities require nearly monochromatic neutron beams. In such experiments, one must accurately measure the mean wavelength of the beam. We seek to reduce the systematic uncertainty of this measurement to approximately 0.1%. This work is motivated mainly by an effort to improve the measurement of the neutron lifetime determined from data collected in a 2003 in-beam experiment performed at NIST. More specifically, we seek to reduce systematic uncertainty by calibrating the neutron detector used in this lifetime experiment. This calibration requires simultaneous measurement of the responses of both the neutron detector used in the lifetime experiment and an absolute black neutron detector to a highly collimated nearly monochromatic beam of cold neutrons, as well as a separate measurement of the mean wavelength of the neutron beam. The calibration uncertainty will depend on the uncertainty of the measured efficiency of the black neutron detector and the uncertainty of the measured mean wavelength. The mean wavelength of the beam is measured by Bragg diffracting the beam from a nearly perfect silicon analyzer crystal. Given the rocking curve data and knowledge of the directions of the rocking axis and the normal to the scattering planes in the silicon crystal, one determines the mean wavelength of the beam. In practice, the direction of the rocking axis and the normal to the silicon scattering planes are not known exactly. Based on Monte Carlo simulation studies, we quantify systematic uncertainties in the mean wavelength measurement due to these geometric errors. Both theoretical and empirical results are presented and compared.

New tests of the common calibration context for ISO, IRTS, and MSX

Science.gov (United States)

Cohen, Martin

1997-01-01

The work carried out in order to test, verify and validate the accuracy of the calibration spectra provided to the Infrared Space Observatory (ISO), to the Infrared Telescope in Space (IRTS) and to the Midcourse Space Experiment (MSX) for external calibration support of instruments, is reviewed. The techniques, used to vindicate the accuracy of the absolute spectra, are discussed. The work planned for comparing far infrared spectra of Mars and some of the bright stellar calibrators with long wavelength spectrometer data are summarized.

Intercomparison of aerosol measurements performed with multi-wavelength Raman lidars, automatic lidars and ceilometers in the framework of INTERACT-II campaign

Science.gov (United States)

Madonna, Fabio; Rosoldi, Marco; Lolli, Simone; Amato, Francesco; Vande Hey, Joshua; Dhillon, Ranvir; Zheng, Yunhui; Brettle, Mike; Pappalardo, Gelsomina

2018-04-01

Following the previous efforts of INTERACT (INTERcomparison of Aerosol and Cloud Tracking), the INTERACT-II campaign used multi-wavelength Raman lidar measurements to assess the performance of an automatic compact micro-pulse lidar (MiniMPL) and two ceilometers (CL51 and CS135) in providing reliable information about optical and geometric atmospheric aerosol properties. The campaign took place at the CNR-IMAA Atmospheric Observatory (760 m a. s. l. ; 40.60° N, 15.72° E) in the framework of ACTRIS-2 (Aerosol Clouds Trace gases Research InfraStructure) H2020 project. Co-located simultaneous measurements involving a MiniMPL, two ceilometers and two EARLINET multi-wavelength Raman lidars were performed from July to December 2016. The intercomparison highlighted that the MiniMPL range-corrected signals (RCSs) show, on average, a fractional difference with respect to those of CNR-IMAA Atmospheric Observatory (CIAO) lidars ranging from 5 to 15 % below 2.0 km a.s.l. (above sea level), largely due to the use of an inaccurate overlap correction, and smaller than 5 % in the free troposphere. For the CL51, the attenuated backscatter values have an average fractional difference with respect to CIAO lidars performance is similar to the CL51 below 2.0 km a. s. l. , while in the region above 3 km a. s. l. the differences are about ±40 %. The variability of the CS135 normalization constant is within ±47 %.Finally, additional tests performed during the campaign using the CHM15k ceilometer operated at CIAO showed the clear need to investigate the CHM15k historical dataset (2010-2016) to evaluate potential effects of ceilometer laser fluctuations on calibration stability. The number of laser pulses shows an average variability of 10 % with respect to the nominal power which conforms to the ceilometer specifications. Nevertheless, laser pulses variability follows seasonal behavior with an increase in the number of laser pulses in summer and a decrease in winter. This contributes to

ATLAS Tile calorimeter calibration and monitoring systems

CERN Document Server

Marjanovic, Marija; The ATLAS collaboration

2018-01-01

The ATLAS Tile Calorimeter (TileCal) is the central section of the hadronic calorimeter of the ATLAS experiment. This sampling calorimeter uses steel plates as absorber and scintillating tiles as active medium. The light produced by the passage of charged particles is transmitted by wavelength shifting fibers to photo-multiplier tubes (PMTs), located in the outer part of the calorimeter. The readout is segmented into about 5000 cells, each one being read out by two PMTs in parallel. To calibrate and monitor the stability and performance of the full readout chain during the data taking, a set of calibration sub-systems is used. The TileCal calibration system comprises Cesium radioactive sources, laser, charge injection elements, and an integrator based readout system. Combined information from all systems allows to monitor and to equalize the calorimeter response at each stage of the signal evolution, from scintillation light to digitization. Calibration runs are monitored from a data quality perspective and u...

A New Indicator for Optimal Preprocessing and Wavelengths Selection of Near-Infrared Spectra

NARCIS (Netherlands)

Skibsted, E.; Boelens, H.F.M.; Westerhuis, J.A.; Witte, D.T.; Smilde, A.K.

2004-01-01

Preprocessing of near-infrared spectra to remove unwanted, i.e., non-related spectral variation and selection of informative wavelengths is considered to be a crucial step prior to the construction of a quantitative calibration model. The standard methodology when comparing various preprocessing

Precision Determination of Atmospheric Extinction at Optical and Near IR Wavelengths

Energy Technology Data Exchange (ETDEWEB)

Burke, David L.; /SLAC; Axelrod, T.; /Arizona U., Astron. Dept. - Steward Observ.; Blondin, Stephane; /European Southern Observ. /Marseille, CPPM; Claver, Chuck; /NOAO, Tucson; Ivezic, Zeljko; Jones, Lynne; /Washington U., Seattle, Astron. Dept.; Saha, Abhijit; /NOAO, Tucson; Smith, Allyn; /Austin Peay State U.; Smith, R.Chris; /Cerro-Tololo InterAmerican Obs.; Stubbs, Christopher W.; /Harvard-Smithsonian Ctr. Astrophys.

2011-08-24

The science goals for future ground-based all-sky surveys, such as the Dark Energy Survey, PanSTARRS, and the Large Synoptic Survey Telescope, require calibration of broadband photometry that is stable in time and uniform over the sky to precisions of a per cent or better, and absolute calibration of color measurements that are similarly accurate. This performance will need to be achieved with measurements made from multiple images taken over the course of many years, and these surveys will observe in less than ideal conditions. This paper describes a technique to implement a new strategy to directly measure variations of atmospheric transmittance at optical wavelengths and application of these measurements to calibration of ground-based observations. This strategy makes use of measurements of the spectra of a small catalog of bright 'probe' stars as they progress across the sky and back-light the atmosphere. The signatures of optical absorption by different atmospheric constituents are recognized in these spectra by their characteristic dependences on wavelength and airmass. State-of-the-art models of atmospheric radiation transport and modern codes are used to accurately compute atmospheric extinction over a wide range of observing conditions. We present results of an observing campaign that demonstrate that correction for extinction due to molecular constituents and aerosols can be done with precisions of a few millimagnitudes with this technique.

A flux calibration device for the SuperNova Integral Field Spectrograph (SNIFS)

Science.gov (United States)

Lombardo, Simona; Aldering, Greg; Hoffmann, Akos; Kowalski, Marek; Kuesters, Daniel; Reif, Klaus; Rigault, Michael

2014-07-01

Observational cosmology employing optical surveys often require precise flux calibration. In this context we present SNIFS Calibration Apparatus (SCALA), a flux calibration system developed for the SuperNova Integral Field Spectrograph (SNIFS), operating at the University of Hawaii 2.2 m telescope. SCALA consists of a hexagonal array of 18 small parabolic mirrors distributed over the face of, and feeding parallel light to, the telescope entrance pupil. The mirrors are illuminated by integrating spheres and a wavelength-tunable (from UV to IR) light source, generating light beams with opening angles of 1°. These nearly parallel beams are flat and flux-calibrated at a subpercent level, enabling us to calibrate our "telescope + SNIFS system" at the required precision.

The ATLAS Electromagnetic Calorimeter Calibration Workshop

CERN Multimedia

Hong Ma; Isabelle Wingerter

The ATLAS Electromagnetic Calorimeter Calibration Workshop took place at LAPP-Annecy from the 1st to the 3rd of October; 45 people attended the workshop. A detailed program was setup before the workshop. The agenda was organised around very focused presentations where questions were raised to allow arguments to be exchanged and answers to be proposed. The main topics were: Electronics calibration Handling of problematic channels Cluster level corrections for electrons and photons Absolute energy scale Streams for calibration samples Calibration constants processing Learning from commissioning Forty-five people attended the workshop. The workshop was on the whole lively and fruitful. Based on years of experience with test beam analysis and Monte Carlo simulation, and the recent operation of the detector in the commissioning, the methods to calibrate the electromagnetic calorimeter are well known. Some of the procedures are being exercised in the commisssioning, which have demonstrated the c...

Enhancement of Faraday effect in one-dimensional magneto-optical photonic crystal including a magnetic layer with wavelength dependent off-diagonal elements of dielectric constant tensor

International Nuclear Information System (INIS)

Inui, Chie; Ozaki, Shinsuke; Kura, Hiroaki; Sato, Tetsuya

2011-01-01

Optical and magneto-optical properties of one-dimensional magneto-optical photonic crystal (1-D MPC) prepared by the sol-gel dip-coating method, including a magnetic defect layer composed of mixture of CoFe 2 O 4 and SiO 2 , are investigated from both the experimental and theoretical standpoints. The resonant transmission of light was observed around 570 nm in the photonic band gap. The Faraday rotation angle θ F showed two maxima at 490 and 640 nm, and the wavelength dependence of θ F above 760 nm was similar to that of the CoFe 2 O 4 +SiO 2 single-layer film. The two maxima of θ F are attributed to the enhanced Faraday rotation of nonmagnetic TiO 2 layers in the cavity structure and that in magnetic CoFe 2 O 4 +SiO 2 layer through the light localization in MPC. The maximum value of θ F due to the magnetic CoFe 2 O 4 +SiO 2 layer in the MPC was 22-times larger than that in the single-layer film. The simulation study of MPC with CoFe 2 O 4 +SiO 2 magnetic defect layer, based on the matrix approach method, showed that the resonant light transmission was accompanied by the localization of electric field, and large enhancement of θ F appeared at different wavelengths so as to agree with the experimental features. This can be explained in terms of the wavelength dependent off-diagonal components of the dielectric constant tensor in addition to the large extinction coefficient in the CoFe 2 O 4 +SiO 2 magnetic defect layer. - Highlights: → 1-D magnetic photonic crystal (MPC) prepared by sol-gel method. → Enhancement of Faraday rotation due to the magnetic defect layer of CoFe 2 O 4 . → Shift of wavelength of Faraday rotation maximum from resonant light transmission.

Radiation protection dosimetry and calibrations

International Nuclear Information System (INIS)

Verhavere, Ph.

2007-01-01

At the SCK-CEN different specialised services are delivered for a whole range of external and internal customers in the radiation protection area. For the expertise group of radiation protection dosimetry and calibrations, these services are organized in four different laboratories: dosimetry, anthropogammametry, nuclear calibrations and non-nuclear calibrations. The services are given by a dedicated technical staff who has experience in the handling of routine and specialised cases. The scientific research that is performed by the expertise group makes sure that state-of-the-art techniques are being used, and that constant improvements and developments are implemented. Quality Assurance is an important aspect for the different services, and accreditation according national and international standards is achieved for all laboratories

Plasma shifts of C VI Lyman lines to shorter wavelengths. Final report, November 4, 1981-September 30, 1983

International Nuclear Information System (INIS)

Griem, H.R.

1984-07-01

The first two years of this ongoing research program were devoted to experimental observations of shifts and widths of hydrogenic ion lines emitted by very dense plasmas. This search is an essential step in the general study of the properties of bound states of multiply charged ions in dense plasmas. This research is of importance in a number of areas, notably equilibrium statistical mechanics (equation of state), plasma radiation physics (energy transport and diagnostics) and calibration of wavelengths in the extreme vacuum uv region (10 A < lambda < 200 A). In the latter case, the wavelengths of lines from one-electron ions are generally accepted to be well known theoretically and are considered as standards for plate calibration. The question nevertheless arises whether or not significant changes in wavelength can occur, e.g., in low-inductance sparks or laser produced plasma which are often used as line sources

MODIS Aqua Optical Throughput Degradation Impact on Relative Spectral Response and Calibration on Ocean Color Products

Science.gov (United States)

Lee, Shihyan; Meister, Gerhard

2017-01-01

Since Moderate Resolution Imaging Spectroradiometer Aqua's launch in 2002, the radiometric system gains of the reflective solar bands have been degrading, indicating changes in the systems optical throughput. To estimate the optical throughput degradation, the electronic gain changes were estimated and removed from the measured system gain. The derived optical throughput degradation shows a rate that is much faster in the shorter wavelengths than the longer wavelengths. The wavelength-dependent optical throughput degradation modulated the relative spectral response (RSR) of the bands. In addition, the optical degradation is also scan angle-dependent due to large changes in response versus the scan angle over time. We estimated the modulated RSR as a function of time and scan angles and its impacts on sensor radiometric calibration for the ocean science. Our results show that the calibration bias could be up to 1.8 % for band 8 (412 nm) due to its larger out-of-band response. For the other ocean bands, the calibration biases are much smaller with magnitudes at least one order smaller.

Non-uniformity calibration for MWIR polarization imagery obtained with integrated microgrid polarimeters

Science.gov (United States)

Liu, Hai-Zheng; Shi, Ze-Lin; Feng, Bin; Hui, Bin; Zhao, Yao-Hong

2016-03-01

Integrating microgrid polarimeters on focal plane array (FPA) of an infrared detector causes non-uniformity of polarization response. In order to reduce the effect of polarization non-uniformity, this paper constructs an experimental setup for capturing raw flat-field images and proposes a procedure for acquiring non-uniform calibration (NUC) matrix and calibrating raw polarization images. The proposed procedure takes the incident radiation as a polarization vector and offers a calibration matrix for each pixel. Both our matrix calibration and two-point calibration are applied to our mid-wavelength infrared (MWIR) polarization imaging system with integrated microgrid polarimeters. Compared with two point calibration, our matrix calibration reduces non-uniformity by 30 40% under condition of flat-field data test with polarization. The ourdoor scene observation experiment indicates that our calibration can effectively reduce polarization non-uniformity and improve the image quality of our MWIR polarization imaging system.

Optical wavelength selection for portable hemoglobin determination by near-infrared spectroscopy method

Science.gov (United States)

Tian, Han; Li, Ming; Wang, Yue; Sheng, Dinggao; Liu, Jun; Zhang, Linna

2017-11-01

Hemoglobin concentration is commonly used in clinical medicine to diagnose anemia, identify bleeding, and manage red blood cell transfusions. The golden standard method for determining hemoglobin concentration in blood requires reagent. Spectral methods were advantageous at fast and non-reagent measurement. However, model calibration with full spectrum is time-consuming. Moreover, it is necessary to use a few variables considering size and cost of instrumentation, especially for a portable biomedical instrument. This study presents different wavelength selection methods for optical wavelengths for total hemoglobin concentration determination in whole blood. The results showed that modelling using only two wavelengths combination (1143 nm, 1298 nm) can keep on the fine predictability with full spectrum. It appears that the proper selection of optical wavelengths can be more effective than using the whole spectra for determination hemoglobin in whole blood. We also discussed the influence of water absorptivity on the wavelength selection. This research provides valuable references for designing portable NIR instruments determining hemoglobin concentration, and may provide some experience for noninvasive hemoglobin measurement by NIR methods.

Calibration samples for accelerator mass spectrometry

International Nuclear Information System (INIS)

Hershberger, R.L.; Flynn, D.S.; Gabbard, F.

1981-01-01

Radioactive samples with precisely known numbers of atoms are useful as calibration sources for lifetime measurements using accelerator mass spectrometry. Such samples can be obtained in two ways: either by measuring the production rate as the sample is created or by measuring the decay rate after the sample has been obtained. The latter method requires that a large sample be produced and that the decay constant be accurately known. The former method is a useful and independent alternative, especially when the decay constant is not well known. The facilities at the University of Kentucky for precision measurements of total neutron production cross sections offer a source of such calibration samples. The possibilities, while quite extensive, would be limited to the proton rich side of the line of stability because of the use of (p,n) and (α,n) reactions for sample production

Calibration of Tilecal hadronic calorimeter of the ATLAS

International Nuclear Information System (INIS)

Batkova, L.

2009-01-01

The aim of a precise calibration of a calorimeter is to get the best response relationship between the calorimeter and the energy of incident particles. Different types of particles interact through various types of interactions with the environment. Therefore, calorimeters are optimized to detect one type of particle (electromagnetic particles and hadrons). Within current high energy physics experiments, where the detectors reached gigantic proportions, calorimeters hold two important features: - serve to measure power showers by complete absorption method; - reconstruct a direction of showers of particles after their interaction with the environment of calorimeter. To deterioration of the resolving power of the hadronic calorimeter contributes incompensation of its response to hadrons and electromagnetic particles (e, μ). They record more energy from electrons as from pions of the same nominal power. During building of experiment of the ATLAS the prototypes of Tile calorimeter were calibrated using Cs and then were tested by means of calibration particle beams (e, μ, π). The work is aimed to evaluation of the response of the muon beam calibration experiment ATLAS. The scope of the work is to determine correction factors for the calibration constants obtained from the primary calibration of the calorimeter by cesium for end Tilecal calorimeter modules. Tile calorimeter modules consist of three layers A, BC and D. A correction factor for calibration constant for A layer was determined by electron beam firing angle less than 20 grad. Muons are used to determine correction factors for the remaining two layers of the end calorimeter module, where the electrons of given energy do not penetrate. (author)

In-flight calibration methods used for the Ørsted mission

DEFF Research Database (Denmark)

Olsen, Nils; Risbo, Torben; Brauer, Peter

2000-01-01

Several methods have been developed for the in-flight calibration of the Ørsted vector magnetometer. They are based on one of the following principles: a) estimating of the magnetometer constants by means of a scalar calibration (comparison of the vector magnetometer (CSC) with the scalar Overhau...

Three-dimensional calibration targets for optical coherence tomography

Science.gov (United States)

Gabriele Sandrian, Michelle; Tomlins, Pete; Woolliams, Peter; Rasakanthan, Janarthanan; Lee, Graham C.; Yang, Anna; Považay, Boris; Alex, Aneesh; Sugden, Kate; Drexler, Wolfgang

2012-03-01

The recent expansion of clinical applications for optical coherence tomography (OCT) is driving the development of approaches for consistent image acquisition. There is a simultaneous need for time-stable, easy-to-use imaging targets for calibration and standardization of OCT devices. We present calibration targets consisting of three-dimensional structures etched into nanoparticle-embedded resin. Spherical iron oxide nanoparticles with a predominant particle diameter of 400 nm were homogeneously dispersed in a two part polyurethane resin and allowed to harden overnight. These samples were then etched using a precision micromachining femtosecond laser with a center wavelength of 1026 nm, 100kHz repetition rate and 450 fs pulse duration. A series of lines in depth were etched, varying the percentage of inscription energy and speed of the translation stage moving the target with respect to the laser. Samples were imaged with a dual wavelength spectral-domain OCT system (λ=800nm, ▵λ~180nm, and λ=1325nm, ▵λ~100nm) and point-spread function of nanoparticles within the target was measured.

Description and calibration beamline SEM/Ion Chamber Current Digitizer

International Nuclear Information System (INIS)

Schoo, D.

1994-05-01

This report discusses the following on beamline SEM/ion chamber current digitizers: Module description; testing and calibration; common setup procedures; summary of fault indications and associated causes; summary of input and output connections; SEM conversion constant table; ion chamber conversion constant table; hexadecimal to decimal conversion table; and schematic diagram

Dual-wavelength phase-shifting digital holography selectively extracting wavelength information from wavelength-multiplexed holograms.

Science.gov (United States)

Tahara, Tatsuki; Mori, Ryota; Kikunaga, Shuhei; Arai, Yasuhiko; Takaki, Yasuhiro

2015-06-15

Dual-wavelength phase-shifting digital holography that selectively extracts wavelength information from five wavelength-multiplexed holograms is presented. Specific phase shifts for respective wavelengths are introduced to remove the crosstalk components and extract only the object wave at the desired wavelength from the holograms. Object waves in multiple wavelengths are selectively extracted by utilizing 2π ambiguity and the subtraction procedures based on phase-shifting interferometry. Numerical results show the validity of the proposed technique. The proposed technique is also experimentally demonstrated.

Full-Field Calibration of Color Camera Chromatic Aberration using Absolute Phase Maps.

Science.gov (United States)

Liu, Xiaohong; Huang, Shujun; Zhang, Zonghua; Gao, Feng; Jiang, Xiangqian

2017-05-06

The refractive index of a lens varies for different wavelengths of light, and thus the same incident light with different wavelengths has different outgoing light. This characteristic of lenses causes images captured by a color camera to display chromatic aberration (CA), which seriously reduces image quality. Based on an analysis of the distribution of CA, a full-field calibration method based on absolute phase maps is proposed in this paper. Red, green, and blue closed sinusoidal fringe patterns are generated, consecutively displayed on an LCD (liquid crystal display), and captured by a color camera from the front viewpoint. The phase information of each color fringe is obtained using a four-step phase-shifting algorithm and optimum fringe number selection method. CA causes the unwrapped phase of the three channels to differ. These pixel deviations can be computed by comparing the unwrapped phase data of the red, blue, and green channels in polar coordinates. CA calibration is accomplished in Cartesian coordinates. The systematic errors introduced by the LCD are analyzed and corrected. Simulated results show the validity of the proposed method and experimental results demonstrate that the proposed full-field calibration method based on absolute phase maps will be useful for practical software-based CA calibration.

ESTABLISHING BRDF CALIBRATION CAPABILITIES THROUGH SHORTWAVE INFRARED

OpenAIRE

Georgiev, Georgi T.; Butler, James J.; Thome, Kurt; Cooksey, Catherine; Ding, Leibo

2017-01-01

Satellite instruments operating in the reflective solar wavelength region require accurate and precise determination of the Bidirectional Reflectance Distribution Functions (BRDFs) of the laboratory and flight diffusers used in their pre-flight and on-orbit calibrations. This paper advances that initial work and presents a comparison of spectral Bidirectional Reflectance Distribution Function (BRDF) and Directional Hemispherical Reflectance (DHR) of Spectralon*, a common material for laborato...

Method for lateral force calibration in atomic force microscope using MEMS microforce sensor.

Science.gov (United States)

Dziekoński, Cezary; Dera, Wojciech; Jarząbek, Dariusz M

2017-11-01

In this paper we present a simple and direct method for the lateral force calibration constant determination. Our procedure does not require any knowledge about material or geometrical parameters of an investigated cantilever. We apply a commercially available microforce sensor with advanced electronics for direct measurement of the friction force applied by the cantilever's tip to a flat surface of the microforce sensor measuring beam. Due to the third law of dynamics, the friction force of the equal value tilts the AFM cantilever. Therefore, torsional (lateral force) signal is compared with the signal from the microforce sensor and the lateral force calibration constant is determined. The method is easy to perform and could be widely used for the lateral force calibration constant determination in many types of atomic force microscopes. Copyright © 2017 Elsevier B.V. All rights reserved.

Real-Time and Meter-Scale Absolute Distance Measurement by Frequency-Comb-Referenced Multi-Wavelength Interferometry.

Science.gov (United States)

Wang, Guochao; Tan, Lilong; Yan, Shuhua

2018-02-07

We report on a frequency-comb-referenced absolute interferometer which instantly measures long distance by integrating multi-wavelength interferometry with direct synthetic wavelength interferometry. The reported interferometer utilizes four different wavelengths, simultaneously calibrated to the frequency comb of a femtosecond laser, to implement subwavelength distance measurement, while direct synthetic wavelength interferometry is elaborately introduced by launching a fifth wavelength to extend a non-ambiguous range for meter-scale measurement. A linearity test performed comparatively with a He-Ne laser interferometer shows a residual error of less than 70.8 nm in peak-to-valley over a 3 m distance, and a 10 h distance comparison is demonstrated to gain fractional deviations of ~3 × 10 -8 versus 3 m distance. Test results reveal that the presented absolute interferometer enables precise, stable, and long-term distance measurements and facilitates absolute positioning applications such as large-scale manufacturing and space missions.

Broadband interference lithography at extreme ultraviolet and soft x-ray wavelengths.

Science.gov (United States)

Mojarad, Nassir; Fan, Daniel; Gobrecht, Jens; Ekinci, Yasin

2014-04-15

Manufacturing efficient and broadband optics is of high technological importance for various applications in all wavelength regimes. Particularly in the extreme ultraviolet and soft x-ray spectra, this becomes challenging due to the involved atomic absorption edges that rapidly change the optical constants in these ranges. Here we demonstrate a new interference lithography grating mask that can be used for nanopatterning in this spectral range. We demonstrate photolithography with cutting-edge resolution at 6.5 and 13.5 nm wavelengths, relevant to the semiconductor industry, as well as using 2.5 and 4.5 nm wavelength for patterning thick photoresists and fabricating high-aspect-ratio metal nanostructures for plasmonics and sensing applications.

Compact optical technique for streak camera calibration

International Nuclear Information System (INIS)

Bell, Perry; Griffith, Roger; Hagans, Karla; Lerche, Richard; Allen, Curt; Davies, Terence; Janson, Frans; Justin, Ronald; Marshall, Bruce; Sweningsen, Oliver

2004-01-01

To produce accurate data from optical streak cameras requires accurate temporal calibration sources. We have reproduced an older technology for generating optical timing marks that had been lost due to component availability. Many improvements have been made which allow the modern units to service a much larger need. Optical calibrators are now available that produce optical pulse trains of 780 nm wavelength light at frequencies ranging from 0.1 to 10 GHz, with individual pulse widths of approximately 25 ps full width half maximum. Future plans include the development of single units that produce multiple frequencies to cover a wide temporal range, and that are fully controllable via an RS232 interface

Compact optical technique for streak camera calibration

Science.gov (United States)

Bell, Perry; Griffith, Roger; Hagans, Karla; Lerche, Richard; Allen, Curt; Davies, Terence; Janson, Frans; Justin, Ronald; Marshall, Bruce; Sweningsen, Oliver

2004-10-01

To produce accurate data from optical streak cameras requires accurate temporal calibration sources. We have reproduced an older technology for generating optical timing marks that had been lost due to component availability. Many improvements have been made which allow the modern units to service a much larger need. Optical calibrators are now available that produce optical pulse trains of 780 nm wavelength light at frequencies ranging from 0.1 to 10 GHz, with individual pulse widths of approximately 25 ps full width half maximum. Future plans include the development of single units that produce multiple frequencies to cover a wide temporal range, and that are fully controllable via an RS232 interface.

On Semi-classical Degravitation and the Cosmological Constant Problems

CERN Document Server

Patil, Subodh P

2010-01-01

In this report, we discuss a candidate mechanism through which one might address the various cosmological constant problems. We first observe that the renormalization of gravitational couplings (induced by integrating out various matter fields) manifests non-local modifications to Einstein's equations as quantum corrected equations of motion. That is, at the loop level, matter sources curvature through a gravitational coupling that is a non-local function of the covariant d'Alembertian. If the functional form of the resulting Newton's `constant' is such that it annihilates very long wavelength sources, but reduces to $1/M^2_{pl}$ ($M_{pl}$ being the 4d Planck mass) for all sources with cosmologically observable wavelengths, we would have a complimentary realization of the degravitation paradigm-- a realization through which its non-linear completion and the corresponding modified Bianchi identities are readily understood. We proceed to consider various theories whose coupling to gravity may a priori induce no...

Calibration curves for quantifying praseodymium by UV-VIS

International Nuclear Information System (INIS)

Gonzalez M, R.; Lopez G, H.; Rojas H, A.

2007-01-01

The UV-Vis spectroscopic technique was used to determine the absorption bands depending on the concentration from the praseodymium solutions at pH3. Those more appropriate were in the wavelength of 215 nm, for concentrations of 0.0001-0.026 M, of 481nm, 468 nm and 443 nm, for concentrations of 0.026-0.325 M, and of 589 nm, for concentrations of 0.026-0.65 M of the praseodymium. To these wavelengths the calibration curves were determined, which presented correlation coefficients between 0.9976 and 0.9999 except of the absorption of 589 nm that gave R 2 = 0.9014. (Author)

A calibration method for phoswich detectors

CERN Document Server

Gawlikowicz, W; Schröder, W U

2002-01-01

A new method of particle identification and energy calibration is proposed for phoswich detectors consisting of a fast plastic scintillator optically coupled to a CsI(Tl) crystal. In this method, functional relationships between integrated yields of three properly selected portions of the observed composite light output signal are parameterized in terms of three physical components (overlapping in time) of this signal. Then, a complete set of calibration constants is derived, linking these integrated partial yields to particle atomic numbers (Z) and energies (E). The calibration is based on the correlations between partial yields observed in actual data from the physics or 'production' runs, and energy deposits calculated for detector elements. The method is found suitable for a wide range of incident particle species and energies, largely eliminating the need for costly and time-consuming conventional calibration experiments with a variety of beams, targets, and bombarding energies.

Wavelength-modulated spectroscopy of the sub-bandgap response of solar cell devices

Energy Technology Data Exchange (ETDEWEB)

Mandanirina, N.H., E-mail: s213514095@nmmu.ac.za; Botha, J.R.; Wagener, M.C.

2016-01-01

A wavelength-modulation setup for measuring the differential photo-response of a GaSb/GaAs quantum ring solar cell structure is reported. The pseudo-monochromatic wavelength is modulated at the output of a conventional monochromator by means of a vibrating slit mechanism. The vibrating slit was able to modulate the excitation wavelength up to 33 nm. The intensity of the light beam was kept constant through a unique flux correction module, designed and built in-house. The setup enabled measurements in the near-infrared range (from 1000 to 1300 nm), which is specifically used to probe the sub-band gap differential photo-response of GaAs solar cells.

Effective optical constants and effective optical properties of ultrathin trilayer structures

International Nuclear Information System (INIS)

Haija, A.J.; Larry Freeman, W.; Umbel, Rachel

2011-01-01

This work presents an extension of the characteristic effective medium approximation (CEMA) to ultrathin trilayer systems. The extension has been carried out analytically and is supported by corresponding calculations of the effective optical constants of Cu-Au-Cu and Ag-SiO-Ag trilayer systems using the CEMA approximation. This work is in essence a generalization of the characteristic effective medium approximation introduced earlier for ultrathin bilayer structures. This method is used to derive the effective optical constants of a trilayer system, consisting of three thin layers with each constituent layer of thickness much less than the wavelength of the incident radiation. Within this regime a trilayer system is viewed as one effective layer referred to as an effective stack (ES) with well defined effective optical constants, which can be used to calculate the optical properties of the trilayer stack within a specified wavelength range. The CEMA based calculations of the effective optical constants are applied to two trilayer systems with a total of five stacks. Three are Cu-Au-Cu and two are Ag-SiO-Ag stacks. The thicknesses of the parent layers in the Cu-Au-Cu stack range from 3 to 30 nm for Cu and 4 to 40 nm for Au; in the Ag-SiO-Ag stack the constituent layers are 6 nm for Ag, but range from 5 to 10 nm for SiO. This study is for normal or near normal incidence spectroscopy in a wavelength range that extends from visible to near infrared. The agreement between CEMA based ES stack results and those of the standard CMT technique is very satisfactory.

Optical power calibrator based on a stabilized green He-Ne laser and a cryogenic absolute radiometer

International Nuclear Information System (INIS)

Varpula, T.; Seppa, H.; Saari, J.M.

1989-01-01

This paper describes an optical power calibrator whose overall calibration uncertainty is less than 10 -4 for an optical power of 0.13 mW. The laser light source of the system operates at a wavelength of 543.5 nm, being close to the wavelength at which the candela is defined, 555 nm. A stable optical power is achieved by stabilizing the intensity and the frequency of a green He-Ne laser. The optical power is detected by a cryogenic absolute radiometer based on the principle of electrical substitution radiometry. It can be employed to measure optical power up to 0.5 mW in the visible and near infrared region

Quantitative comparison of two independent lateral force calibration techniques for the atomic force microscope

International Nuclear Information System (INIS)

Barkley, Sarice S.; Cannara, Rachel J.; Deng Zhao; Gates, Richard S.; Reitsma, Mark G.

2012-01-01

Two independent lateral-force calibration methods for the atomic force microscope (AFM)--the hammerhead (HH) technique and the diamagnetic lateral force calibrator (D-LFC)--are systematically compared and found to agree to within 5% or less, but with precision limited to about 15%, using four different tee-shaped HH reference probes. The limitations of each method, both of which offer independent yet feasible paths toward traceable accuracy, are discussed and investigated. We find that stiff cantilevers may produce inconsistent D-LFC values through the application of excessively high normal loads. In addition, D-LFC results vary when the method is implemented using different modes of AFM feedback control, constant height and constant force modes, where the latter is more consistent with the HH method and closer to typical experimental conditions. Specifically, for the D-LFC apparatus used here, calibration in constant height mode introduced errors up to 14 %. In constant force mode using a relatively stiff cantilever, we observed an ≅ 4 % systematic error per μN of applied load for loads ≤ 1 μN. The issue of excessive load typically emerges for cantilevers whose flexural spring constant is large compared with the normal spring constant of the D-LFC setup (such that relatively small cantilever flexural displacements produce relatively large loads). Overall, the HH method carries a larger uncertainty, which is dominated by uncertainty in measurement of the flexural spring constant of the HH cantilever as well as in the effective length dimension of the cantilever probe. The D-LFC method relies on fewer parameters and thus has fewer uncertainties associated with it. We thus show that it is the preferred method of the two, as long as care is taken to perform the calibration in constant force mode with low applied loads.

ATLAS Tile calorimeter calibration and monitoring systems

CERN Document Server

Cortes-Gonzalez, Arely; The ATLAS collaboration

2017-01-01

The ATLAS Tile Calorimeter is the central section of the hadronic calorimeter of the ATLAS experiment and provides important information for reconstruction of hadrons, jets, hadronic decays of tau leptons and missing transverse energy. This sampling calorimeter uses steel plates as absorber and scintillating tiles as active medium. The light produced by the passage of charged particles is transmitted by wavelength shifting fibres to photomultiplier tubes, located in the outer part of the calorimeter. The readout is segmented into about 5000 cells (longitudinally and transversally), each of them being read out by two photomultiplier in parallel. To calibrate and monitor the stability and performance of each part of the readout chain during the data taking, a set of calibration systems is used. The calibration system comprises Cesium radioactive sources, laser, charge injection elements and an integrator based readout system. Combined information from all systems allows to monitor and equalise the calorimeter r...

ATLAS Tile calorimeter calibration and monitoring systems

CERN Document Server

Boumediene, Djamel Eddine; The ATLAS collaboration

2017-01-01

The ATLAS Tile Calorimeter (TileCal) is the central section of the hadronic calorimeter of the ATLAS experiment and provides important information for reconstruction of hadrons, jets, hadronic decays of tau leptons and missing transverse energy. This sampling calorimeter uses steel plates as absorber and scintillating tiles as active medium. The light produced by the passage of charged particles is transmitted by wavelength shifting fibres to photomultiplier tubes (PMTs). PMT signals are then digitized at 40 MHz and stored on detector and are only transferred off detector once the first level trigger acceptance has been confirmed. The readout is segmented into about 5000 cells (longitudinally and transversally), each of them being read out by two PMTs in parallel. To calibrate and monitor the stability and performance of each part of the readout chain, a set of calibration systems is used. The TileCal calibration system comprises Cesium radioactive sources, laser, charge injection elements and an integrator b...

ATLAS Tile calorimeter calibration and monitoring systems

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00445232; The ATLAS collaboration

2016-01-01

The ATLAS Tile Calorimeter (TileCal) is the central section of the hadronic calorimeter of the ATLAS experiment and provides important information for reconstruction of hadrons, jets, hadronic decays of tau leptons and missing transverse energy. This sampling calorimeter uses steel plates as absorber and scintillating tiles as active medium. The light produced by the passage of charged particles is transmitted by wavelength shifting fibres to photomultiplier tubes (PMTs), located on the outside of the calorimeter. The readout is segmented into about 5000 cells (longitudinally and transversally), each of them being read out by two PMTs in parallel. To calibrate and monitor the stability and performance of each part of the readout chain during the data taking, a set of calibration systems is used. The TileCal calibration system comprises Cesium radioactive sources, laser and charge injection elements and it allows to monitor and equalize the calorimeter response at each stage of the signal production, from scin...

ATLAS Tile calorimeter calibration and monitoring systems

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00445232; The ATLAS collaboration

2017-01-01

The ATLAS Tile Calorimeter (TileCal) is the central section of the hadronic calorimeter of the ATLAS experiment and provides important information for reconstruction of hadrons, jets, hadronic decays of tau leptons and missing transverse energy. This sampling calorimeter uses steel plates as absorber and scintillating tiles as active medium. The light produced by the passage of charged particles is transmitted by wavelength shifting fibres to photomultiplier tubes (PMTs), located on the outside of the calorimeter. The readout is segmented into about 5000 cells (longitudinally and transversally), each of them being read out by two PMTs in parallel. To calibrate and monitor the stability and performance of each part of the readout chain during the data taking, a set of calibration systems is used. The TileCal calibration system comprises cesium radioactive sources, Laser and charge injection elements, and allows for monitoring and equalization of the calorimeter response at each stage of the signal production, ...

Real-Time and Meter-Scale Absolute Distance Measurement by Frequency-Comb-Referenced Multi-Wavelength Interferometry

Directory of Open Access Journals (Sweden)

Guochao Wang

2018-02-01

Full Text Available We report on a frequency-comb-referenced absolute interferometer which instantly measures long distance by integrating multi-wavelength interferometry with direct synthetic wavelength interferometry. The reported interferometer utilizes four different wavelengths, simultaneously calibrated to the frequency comb of a femtosecond laser, to implement subwavelength distance measurement, while direct synthetic wavelength interferometry is elaborately introduced by launching a fifth wavelength to extend a non-ambiguous range for meter-scale measurement. A linearity test performed comparatively with a He–Ne laser interferometer shows a residual error of less than 70.8 nm in peak-to-valley over a 3 m distance, and a 10 h distance comparison is demonstrated to gain fractional deviations of ~3 × 10−8 versus 3 m distance. Test results reveal that the presented absolute interferometer enables precise, stable, and long-term distance measurements and facilitates absolute positioning applications such as large-scale manufacturing and space missions.

Low Cost Constant – Head Drip Irrigation Emitter for Climate ...

African Journals Online (AJOL)

Low Cost Constant – Head Drip Irrigation Emitter for Climate Change Adaptation in Nigeria: Engineering Design and Calibration. ... The drip system comprises of abarrel, sub-main line, lateral lines, tubes and emitters, it can irrigate140 crop ...

Calibration of dosimeters at 80-120 keV electron irradiation

DEFF Research Database (Denmark)

Miller, A.; Helt-Hansen, J.

to calibrate thin-film dosimeters (Risø B3 and alanine films) by irradiation at the 80–120 keV electron accelerators. This calibration was compared to a 10MeV calibration, and we show that the radiation response of the dosimeter materials (the radiation chemical yield) is constant at these irradiation energies....... However, dose gradients within the dosimeters, when it is irradiated at low electron energies,mean that calibration function here will depend on both irradiation energy and the required effective point of measurement of the dosimeter. These are general effects that apply to any dosimeter that has a non...

Assessment of MODIS On-Orbit Calibration Using a Deep Convective Cloud Technique

Science.gov (United States)

Mu, Qiaozhen; Wu, Aisheng; Chang, Tiejun; Angal, Amit; Link, Daniel; Xiong, Xiaoxiong; Doelling, David R.; Bhatt, Rajendra

2016-01-01

The MODerate Resolution Imaging Spectroradiometer (MODIS) sensors onboard Terra and Aqua satellites are calibrated on-orbit with a solar diffuser (SD) for the reflective solar bands (RSB). The MODIS sensors are operating beyond their designed lifetime and hence present a major challenge to maintain the calibration accuracy. The degradation of the onboard SD is tracked by a solar diffuser stability monitor (SDSM) over a wavelength range from 0.41 to 0.94 micrometers. Therefore, any degradation of the SD beyond 0.94 micrometers cannot be captured by the SDSM. The uncharacterized degradation at wavelengths beyond this limit could adversely affect the Level 1B (L1B) product. To reduce the calibration uncertainties caused by the SD degradation, invariant Earth-scene targets are used to monitor and calibrate the MODIS L1B product. The use of deep convective clouds (DCCs) is one such method and particularly significant for the short-wave infrared (SWIR) bands in assessing their long-term calibration stability. In this study, we use the DCC technique to assess the performance of the Terra and Aqua MODIS Collection-6 L1B for RSB 1 3- 7, and 26, with spectral coverage from 0.47 to 2.13 micrometers. Results show relatively stable trends in Terra and Aqua MODIS reflectance for most bands. Careful attention needs to be paid to Aqua band 1, Terra bands 3 and 26 as their trends are larger than 1% during the study time period. We check the feasibility of using the DCC technique to assess the stability in MODIS bands 17-19. The assessment test on response versus scan angle (RVS) calibration shows substantial trend difference for Aqua band 1between different angles of incidence (AOIs). The DCC technique can be used to improve the RVS calibration in the future.

Construction, calibration, and application of a compact spectrophotometer for EUV(300-2500 A) plasma diagnostics

International Nuclear Information System (INIS)

Moos, H.W.; Chen, K.I.; Terry, J.L.

1979-01-01

A 400-mm normal incidence concave grating spectrophotometer, specifically designed for plasma diagnostics, is described. The wavelength drive, in which the grating is translated as well as rotated, is discussed in detail; the wavelength linearity of the sine drive and methods of improving it are analyzed. The instrument can be used in any orientation, is portable under vacuum, and quite rugged. The construction techniques utilized produce a high quality vacuum making the instrument compatible with both high purity plasma devices and synchrotron radiation sources. The photometric sensitivity calibration was found to be very stable during extended use on high temperature plasma devices. The applications of the instrument to diagnose plasmas in two tokamaks and a mirror device are decribed. A facility used for photometric calibration of extreme ultraviolet (lambda>300-A) spectrophotometers against NBS standard diodes is described. The instrumental calibration obtained using this facility was checked by using synchrotron radiation from SURF II; very good agreement was observed

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

Energy Technology Data Exchange (ETDEWEB)

Keawprasert, T. [National Institute of Metrology Thailand, Pathum thani (Thailand); Anhalt, K.; Taubert, D. R.; Sperling, A.; Schuster, M.; Nevas, S. [Physikalisch Technische Bundesanstalt, Braunschweig and Berlin (Germany)

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.

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

International Nuclear Information System (INIS)

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

2013-01-01

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

ATLAS Tile calorimeter calibration and monitoring systems

Science.gov (United States)

Chomont, Arthur; ATLAS Collaboration

2017-11-01

The ATLAS Tile Calorimeter (TileCal) is the central section of the hadronic calorimeter of the ATLAS experiment and provides important information for reconstruction of hadrons, jets, hadronic decays of tau leptons and missing transverse energy. This sampling calorimeter uses steel plates as absorber and scintillating tiles as active medium. The light produced by the passage of charged particles is transmitted by wavelength shifting fibres to photomultiplier tubes (PMTs), located on the outside of the calorimeter. The readout is segmented into about 5000 cells (longitudinally and transversally), each of them being read out by two PMTs in parallel. To calibrate and monitor the stability and performance of each part of the readout chain during the data taking, a set of calibration systems is used. The TileCal calibration system comprises cesium radioactive sources, Laser and charge injection elements, and allows for monitoring and equalization of the calorimeter response at each stage of the signal production, from scintillation light to digitization. Based on LHC Run 1 experience, several calibration systems were improved for Run 2. The lessons learned, the modifications, and the current LHC Run 2 performance are discussed.

Magneto-optical measurement of anisotropy energy constant(s) for amorphous rare earth, transition metal alloys

International Nuclear Information System (INIS)

Uber, R.E.; Mansuripur, M.

1988-01-01

Optical investigation of magneto-optical films is complementary to conventional torque and VSM magnetometry. In the authors' laboratory, they are now measuring anisotropy energy constants of RE-TM thin films at temperatures from ambient to 150 0 C. An in-plane magnetic field (up to 16.5 KOe) is applied to a saturated sample with perpendicular magnetization. The movement away from the perpendicular direction is monitored using the polar Kerr effect. At the HeNe wavelength, the Kerr effect is principally due to the top 500 angstroms of the transition metal subnetwork in the films

Multi-wavelength spectrophotometric determination of acidity constant of some newly synthesized Schiff bases and their QSPR study

Science.gov (United States)

Hemmateenejad, Bahram; Emami, Leila; Sharghi, Hashem

2010-01-01

The acidity constants of some newly synthesized Schiff base derivatives were determined by hard-model based multivariate data analysis of the spectrophotometric data in the course of pH-metric titration in 50% (v/v) methanol-water binary solvent. The employed data analysis method was also able to extract the pure spectra and pH-dependent concentration profiles of the acid-base species. The molecules that possess different substituents (both electron donating and withdrawing) on the ortho-, meta- and para-positions of one of the phenyl ring showed variable acidity constants ranging from 8.77 to 11.07 whereas the parent molecule had an acidity constant of 10.25. To investigate the quantitative effects of changing of substitution pattern on the acidity constant, a quantitative structure-property relation analysis was conducted using substituent constants and molecular descriptor. Some models with high statistical quality (measured by cross-validation Q2) were obtained. It was found that the acidity constant of the studied molecules in the methanol-water mixed solvent not only is affected by electronic features of the solutes but also by the lipophilic interaction between methanol part of solvent and the deprotonated solutes.

Gladstone-Dale constant for CF4. [experimental design

Science.gov (United States)

Burner, A. W., Jr.; Goad, W. K.

1980-01-01

The Gladstone-Dale constant, which relates the refractive index to density, was measured for CF4 by counting fringes of a two-beam interferometer, one beam of which passes through a cell containing the test gas. The experimental approach and sources of systematic and imprecision errors are discussed. The constant for CF4 was measured at several wavelengths in the visible region of the spectrum. A value of 0.122 cu cm/g with an uncertainty of plus or minus 0.001 cu cm/g was determined for use in the visible region. A procedure for noting the departure of the gas density from the ideal-gas law is discussed.

Double pulse laser induced breakdown spectroscopy: Experimental study of lead emission intensity dependence on the wavelengths and sample matrix

Energy Technology Data Exchange (ETDEWEB)

Piscitelli S, V; Martinez L, M A; Fernandez C, A J [Laboratorio de Espectroscopia Laser, Escuela de Quimica, Facultad de Ciencias, Universidad Central de Venezuela, Caracas, DC 1020 (Venezuela, Bolivarian Republic of); Gonzalez, J J; Mao, X L [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Russo, R.E. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)], E-mail: RERusso@lbl.gov

2009-02-15

Lead (Pb) emission intensity (atomic line 405.78 nm) dependence on the sample matrix (metal alloy) was studied by means of collinear double pulse (DP)-laser induced breakdown spectroscopy (LIBS). The measurement of the emission intensity produced by three different wavelength combinations (i.e. I:532 nm-II:1064 nm, I:532 nm-II:532 nm, and I:532 nm-II:355 nm) from three series of standard reference materials showed that the lead atomic line 405.78 nm emission intensity was dependent on the sample matrix for all the combination of wavelengths, however reduced dependency was found for the wavelength combination I:532 nm-II:355 nm. Two series of standard reference materials from the National Institute of Standards and Technology (NIST) and one series from the British Chemical Standards (BCS) were used for these experiments. Calibration curves for lead ablated from NIST 626-630 ('Zn{sub 95}Al{sub 4}Cu{sub 1}') provided higher sensitivity (slope) than those calibration curves produced from NIST 1737-1741 ('Zn{sub 99.5}Al{sub 0.5}') and with the series BCS 551-556 ('Cu{sub 87}Sn{sub 11}'). Similar trends between lead emission intensity (calibration curve sensitivities) and reported variations in plasma temperatures caused by the differing ionization potentials of the major and minor elements in these samples were established.

Absolute analytical prediction of photonic crystal guided mode resonance wavelengths

International Nuclear Information System (INIS)

Hermannsson, Pétur Gordon; Vannahme, Christoph; Smith, Cameron L. C.; Kristensen, Anders

2014-01-01

A class of photonic crystal resonant reflectors known as guided mode resonant filters are optical structures that are widely used in the field of refractive index sensing, particularly in biosensing. For the purposes of understanding and design, their behavior has traditionally been modeled numerically with methods such as rigorous coupled wave analysis. Here it is demonstrated how the absolute resonance wavelengths of such structures can be predicted by analytically modeling them as slab waveguides in which the propagation constant is determined by a phase matching condition. The model is experimentally verified to be capable of predicting the absolute resonance wavelengths to an accuracy of within 0.75 nm, as well as resonance wavelength shifts due to changes in cladding index within an accuracy of 0.45 nm across the visible wavelength regime in the case where material dispersion is taken into account. Furthermore, it is demonstrated that the model is valid beyond the limit of low grating modulation, for periodically discontinuous waveguide layers, high refractive index contrasts, and highly dispersive media.

Commissioning the CMS Alignment and Calibration Framework

CERN Document Server

Futyan, David

2009-01-01

The CMS experiment has developed a powerful framework to ensure the precise and prompt alignment and calibration of its components, which is a major prerequisite to achieve the optimal performance for physics analysis. The prompt alignment and calibration strategy harnesses computing resources both at the Tier-0 site and the CERN Analysis Facility (CAF) to ensure fast turnaround for updating the corresponding database payloads. An essential element is the creation of dedicated data streams concentrating the specific event information required by the various alignment and calibration workflows. The resulting low latency is required for feeding the resulting constants into the prompt reconstruction process, which is essential for achieving swift physics analysis of the LHC data. This report discusses the implementation and the computational aspects of the alignment and calibration framework. Recent commissioning campaigns with cosmic muons, beam halo and simulated data have been used to gain detailed experience...

Observational calibration of the projection factor of Cepheids. IV. Period-projection factor relation of Galactic and Magellanic Cloud Cepheids

Science.gov (United States)

Gallenne, A.; Kervella, P.; Mérand, A.; Pietrzyński, G.; Gieren, W.; Nardetto, N.; Trahin, B.

2017-11-01

allow us to accurately apply the BW method to nearby galaxies. Finally, the infrared excesses we detect again raise the issue of using mid-IR wavelengths to derive period-luminosity relation and to calibrate the Hubble constant. These IR excesses might be the signature of circumstellar dust, and are never taken into account when applying the BW method at those wavelengths. Our measured offsets may give an average bias of 2.8% on the distances derived through mid-IR P-L relations.

Rapid, Time-Division Multiplexed, Direct Absorption- and Wavelength Modulation-Spectroscopy

Directory of Open Access Journals (Sweden)

Alexander Klein

2014-11-01

Full Text Available We present a tunable diode laser spectrometer with a novel, rapid time multiplexed direct absorption- and wavelength modulation-spectroscopy operation mode. The new technique allows enhancing the precision and dynamic range of a tunable diode laser absorption spectrometer without sacrificing accuracy. The spectroscopic technique combines the benefits of absolute concentration measurements using calibration-free direct tunable diode laser absorption spectroscopy (dTDLAS with the enhanced noise rejection of wavelength modulation spectroscopy (WMS. In this work we demonstrate for the first time a 125 Hz time division multiplexed (TDM-dTDLAS-WMS spectroscopic scheme by alternating the modulation of a DFB-laser between a triangle-ramp (dTDLAS and an additional 20 kHz sinusoidal modulation (WMS. The absolute concentration measurement via the dTDLAS-technique allows one to simultaneously calibrate the normalized 2f/1f-signal of the WMS-technique. A dTDLAS/WMS-spectrometer at 1.37 µm for H2O detection was built for experimental validation of the multiplexing scheme over a concentration range from 50 to 3000 ppmV (0.1 MPa, 293 K. A precision of 190 ppbV was achieved with an absorption length of 12.7 cm and an averaging time of two seconds. Our results show a five-fold improvement in precision over the entire concentration range and a significantly decreased averaging time of the spectrometer.

The measurement of thermal neutron constants of the soil; application to the calibration of neutron moisture gauges and to the pedological study of soil

International Nuclear Information System (INIS)

Couchat, P.; Marcesse, J.; Carre, C.; Le Ho, J.

1975-01-01

The neutronic method for measuring the water content of soils is more and more used by agronomists, hydrogeologists and pedologists. On the other hand the studies on the phenomena of slowing down and diffusion process have shown a narrow relation between the thermal absorption (Σ(a)) and diffusion (Σ(d)) constants and the thermal flux developed in the soil around a fast neutron source like Am-Be. Two original applications of the direct measurement of Σ(a) and Σ(d) are then presented. The method described consists in the measurement, in a cube of graphite with Am-Be source in the middle, on one side of the perturbation of the thermal flux, obtained by the introduction of 300g of soil, and on the other side of the transmitted thermal flux measured through the same sample of soil, on a side of the cube. After calibrating the device, these two parameters give Σ(a) and Σ(d) which are easily introduced in the calibration equation of neutron moisture gauge. Also these two values are useful for the pedologists because Σ(d) is connected to clay content in the soil and Σ(a) is connected to the type of clay by the way of rare earth contents [fr

Dependence of wavelength of Xe ion-induced rippled structures on the fluence in the medium ion energy range

Energy Technology Data Exchange (ETDEWEB)

Hanisch, Antje; Grenzer, Joerg [Institute of Ion Beam Physics and Materials Research, Dresden (Germany); Biermanns, Andreas; Pietsch, Ullrich [Institute of Physics, University of Siegen (Germany)

2010-07-01

Ion-beam eroded self-organized nanostructures on semiconductors offer new ways for the fabrication of high density memory and optoelectronic devices. It is known that wavelength and amplitude of noble gas ion-induced rippled structures tune with the ion energy and the fluence depending on the energy range, ion type and substrate. The linear theory by Makeev predicts a linear dependence of the ion energy on the wavelength for low temperatures. For Ar{sup +} and O{sub 2}{sup +} it was observed by different groups that the wavelength grows with increasing fluence after being constant up to an onset fluence and before saturation. In this coarsening regime power-law or exponential behavior of the wavelength with the fluence was monitored. So far, investigations for Xe ions on silicon surfaces mainly concentrated on energies below 1 keV. We found a linear dependence of both the ion energy and the fluence on the wavelength and amplitude of rippled structures over a wide range of the Xe{sup +} ion energy between 5 and 70 keV. Moreover, we estimated the ratio of wavelength to amplitude to be constant meaning a shape stability when a threshold fluence of 2.10{sup 17} cm{sup -2} was exceeded.

Calibration of the CREAM calorimeter with beam test data

CERN Document Server

Han, J H; Amare, Y

The Cosmic Ray Energetics An d Mass (CREAM) calorimeter (CAL) is designed to measure cosmic-ray elemental energy spectra from 10 12 eV to 10 15 eV. It is comprised of 20 layers of tungsten interleaved with 20 layers of scintillating fiber ribbons. Before each flight, the CAL is exposed to an electron beam. For CREAM-IV through CREAM-VI, beams of 150 GeV electrons were used for the calibration, and 100 GeV was used for CREAM-VII. For calibration purpose, we compare electron beam data with simulation results to find calibration constants with the unit of MeV/ADC. In this paper, we present calibration results, including energy resolutions for electrons and uniformity of response. We also discuss CAL calibration using various beam test data compared with Monte Carlo (MC) simulation data.

THE BEHAVIOR OF THE PITCH ANGLE OF SPIRAL ARMS DEPENDING ON OPTICAL WAVELENGTH

Energy Technology Data Exchange (ETDEWEB)

Martínez-García, Eric E.; Puerari, Ivânio; Rosales-Ortega, F. F.; Luna, A. [Instituto Nacional de Astrofísica, Óptica y Electrónica (INAOE), Aptdo. Postal 51 y 216, 72000 Puebla, Pue. (Mexico); González-Lópezlira, Rosa A. [Centro de Radioastronomía y Astrofísica, UNAM, Campus Morelia, Michoacán, México, C.P. 58089 (Mexico); Fuentes-Carrera, Isaura, E-mail: ericmartinez@inaoep.mx [Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, U. P. Adolfo López Mateos, Zacatenco, 07730 México, D.F. (Mexico)

2014-09-20

Based on integral field spectroscopy data from the CALIFA survey, we investigate the possible dependence of spiral arm pitch angle with optical wavelength. For three of the five studied objects, the pitch angle gradually increases at longer wavelengths. This is not the case for two objects where the pitch angle remains constant. This result is confirmed by the analysis of SDSS data. We discuss the possible physical mechanisms to explain this phenomenon, as well as the implications of the results.

Calibration and monitoring of the ATLAS Tile calorimeter

CERN Document Server

Boumediene, Djamel Eddine; The ATLAS collaboration

2017-01-01

The ATLAS Tile Calorimeter (TileCal) is the central section of the hadronic calorimeter of the ATLAS experiment and provides important information for reconstruction of hadrons, jets, hadronic decays of tau leptons and missing transverse energy. This sampling calorimeter uses steel plates as absorber and scintillating tiles as active medium. The light produced by the passage of charged particles is transmitted by wavelength shifting fibres to photomultiplier tubes (PMTs). PMT signals are then digitized at 40~MHz and stored on detector and are only transferred off detector once the first level trigger acceptance has been confirmed. The readout is segmented into about 5000 cells (longitudinally and transversally), each of them being read out by two PMTs in parallel. To calibrate and monitor the stability and performance of each part of the readout chain, a set of calibration systems is used. The TileCal calibration system comprises Cesium radioactive sources, laser, charge injection elements and an integrator b...

Status of the calibration and alignment framework at the Belle II experiment

Science.gov (United States)

Dossett, D.; Sevior, M.; Ritter, M.; Kuhr, T.; Bilka, T.; Yaschenko, S.; Belle Software Group, II

2017-10-01

The Belle II detector at the Super KEKB e+e-collider plans to take first collision data in 2018. The monetary and CPU time costs associated with storing and processing the data mean that it is crucial for the detector components at Belle II to be calibrated quickly and accurately. A fast and accurate calibration system would allow the high level trigger to increase the efficiency of event selection, and can give users analysis-quality reconstruction promptly. A flexible framework to automate the fast production of calibration constants is being developed in the Belle II Analysis Software Framework (basf2). Detector experts only need to create two components from C++ base classes in order to use the automation system. The first collects data from Belle II event data files and outputs much smaller files to pass to the second component. This runs the main calibration algorithm to produce calibration constants ready for upload into the conditions database. A Python framework coordinates the input files, order of processing, and submission of jobs. Splitting the operation into collection and algorithm processing stages allows the framework to optionally parallelize the collection stage on a batch system.

Electronic measurement of the Boltzmann constant with a quantum-voltage-calibrated Johnson-noise thermometer

NARCIS (Netherlands)

Benz, Samuel; White, D. Rod; Qu, JiFeng; Rogalla, Horst; Tew, Weston

2010-01-01

Currently, the CODATA value of the Boltzmann constant is dominated by a single gas-based thermometry measurement with a relative standard uncertainty of 1.8×10−6 [P.J. Mohr, B.N. Taylor, D.B. Newell, CODATA recommended values of the fundamental physical constants: 2006, Rev. Mod. Phys. 80 (2008)

RADIOMETRIC CALIBRATION OF AIRBORNE LASER SCANNING DATA

OpenAIRE

Pilarska Magdalena

2016-01-01

Airborne laser scanning (ALS) is widely used passive remote sensing technique. The radiometric calibration of ALS data is presented in this article. This process is a necessary element in data processing since it eliminates the influence of the external factors on the obtained values of radiometric features such as range and incidence angle. The datasets were captured with three different laser scanners; since each of these operates at a different wavelength (532, 106 4 and 1550 nm) th...

Novel xenon calibration scheme for two-photon absorption laser induced fluorescence of hydrogen

Energy Technology Data Exchange (ETDEWEB)

Elliott, Drew; Scime, Earl; Short, Zachary, E-mail: zdshort@mix.wvu.edu [Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26056 (United States)

2016-11-15

Two photon absorption laser induced fluorescence (TALIF) measurements of neutral hydrogen and its isotopes are typically calibrated by performing TALIF measurements on krypton with the same diagnostic system and using the known ratio of the absorption cross sections [K. Niemi et al., J. Phys. D 34, 2330 (2001)]. Here we present the measurements of a new calibration method based on a ground state xenon scheme for which the fluorescent emission wavelength is nearly identical to that of hydrogen, thereby eliminating chromatic effects in the collection optics and simplifying detector calibration. We determine that the ratio of the TALIF cross sections of xenon and hydrogen is 0.024 ± 0.001.

UNDERFLIGHT CALIBRATION OF SOHO/CDS AND HINODE/EIS WITH EUNIS-07

Energy Technology Data Exchange (ETDEWEB)

Wang Tongjiang; Brosius, Jeffrey W. [Institute for Astrophysics and Computational Sciences (IACS) in the Department of Physics, Catholic University of America, 620 Michigan Avenue NE, Washington, DC 20064 (United States); Thomas, Roger J.; Rabin, Douglas M.; Davila, Joseph M. [NASA Goddard Space Flight Center, Code 671, Greenbelt, MD 20771 (United States); Young, Peter R. [College of Science, George Mason University, 4400 University Drive, Fairfax, VA 22030 (United States); Del Zanna, Giulio, E-mail: tongjiang.wang@nasa.gov [DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA (United Kingdom)

2011-12-01

Flights of Goddard Space Flight Center's Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS) sounding rocket in 2006 and 2007 provided updated radiometric calibrations for Solar and Heliospheric Observatory/Coronal Diagnostic Spectrometer (SOHO/CDS) and Hinode/Extreme Ultraviolet Imaging Spectrometer (Hinode/EIS). EUNIS carried two independent imaging spectrographs covering wavebands of 300-370 A in first order and 170-205 A in second order. After each flight, end-to-end radiometric calibrations of the rocket payload were carried out in the same facility used for pre-launch calibrations of CDS and EIS. During the 2007 flight, EUNIS, SOHO/CDS, and Hinode/EIS observed the same solar locations, allowing the EUNIS calibrations to be directly applied to both CDS and EIS. The measured CDS NIS 1 line intensities calibrated with the standard (version 4) responsivities with the standard long-term corrections are found to be too low by a factor of 1.5 due to the decrease in responsivity. The EIS calibration update is performed in two ways. One uses the direct calibration transfer of the calibrated EUNIS-07 short wavelength (SW) channel. The other uses the insensitive line pairs, in which one member was observed by the EUNIS-07 long wavelength (LW) channel and the other by EIS in either the LW or SW waveband. Measurements from both methods are in good agreement, and confirm (within the measurement uncertainties) the EIS responsivity measured directly before the instrument's launch. The measurements also suggest that the EIS responsivity decreased by a factor of about 1.2 after the first year of operation (although the size of the measurement uncertainties is comparable to this decrease). The shape of the EIS SW response curve obtained by EUNIS-07 is consistent with the one measured in laboratory prior to launch. The absolute value of the quiet-Sun He II 304 A intensity measured by EUNIS-07 is consistent with the radiance measured by CDS NIS in quiet regions

Spectral calibration of EBT3 and HD-V2 radiochromic film response at high dose using 20 MeV proton beams

Science.gov (United States)

Feng, Yiwei; Tiedje, Henry F.; Gagnon, Katherine; Fedosejevs, Robert

2018-04-01

Radiochromic film is used extensively in many medical, industrial, and scientific applications. In particular, the film is used in analysis of proton generation and in high intensity laser-plasma experiments where very high dose levels can be obtained. The present study reports calibration of the dose response of Gafchromic EBT3 and HD-V2 radiochromic films up to high exposure densities. A 2D scanning confocal densitometer system is employed to carry out accurate optical density measurements up to optical density 5 on the exposed films at the peak spectral absorption wavelengths. Various wavelengths from 400 to 740 nm are also scanned to extend the practical dose range of such films by measuring the response at wavelengths removed from the peak response wavelengths. Calibration curves for the optical density versus exposure dose are determined and can be used for quantitative evaluation of measured doses based on the measured optical densities. It was found that blue and UV wavelengths allowed the largest dynamic range though at some trade-off with overall accuracy.

Wavelength-Agile Optical Sensor for Exhaust Plume and Cryogenic Fluid Interrogation

Science.gov (United States)

Sanders, Scott T.; Chiaverini, Martin J.; Gramer, Daniel J.

2004-01-01

Two optical sensors developed in UW-Madison labs were evaluated for their potential to characterize rocket engine exhaust plumes and liquid oxygen (LOX) fluid properties. The plume sensor is based on wavelength-agile absorption spectroscopy A device called a chirped white pulse emitter (CWPE) is used to generate the wavelength agile light, scanning, for example, 1340 - 1560 nm every microsecond. Properties of the gases in the rocket plume (for example temperature and water mole fraction) can be monitored using these wavelength scans. We have performed preliminary tests in static gas cells, a laboratory GOX/GH2 thrust chamber, and a solid-fuel hybrid thrust chamber, and these initial tests demonstrate the potential of the CWPE for monitoring rocket plumes. The LOX sensor uses an alternative to wavelength agile sensing: two independent, fixed-wavelength lasers are combined into a single fiber. One laser is absorbed by LOX and the other not: by monitoring the differential transmission the LOX concentration in cryogenic feed lines can be inferred. The sensor was successful in interrogating static LOX pools in laboratory tests. Even in ice- and bubble-laden cryogenic fluids, LOX concentrations were measured to better than 1% with a 3 microsec time constant.

Commissioning the CMS alignment and calibration framework

International Nuclear Information System (INIS)

Futyan, David

2010-01-01

The CMS experiment has developed a powerful framework to ensure the precise and prompt alignment and calibration of its components, which is a major prerequisite to achieve the optimal performance for physics analysis. The prompt alignment and calibration strategy harnesses computing resources both at the Tier-0 site and the CERN Analysis Facility (CAF) to ensure fast turnaround for updating the corresponding database payloads. An essential element is the creation of dedicated data streams concentrating the specific event information required by the various alignment and calibration workflows. The resulting low latency is required for feeding the resulting constants into the prompt reconstruction process, which is essential for achieving swift physics analysis of the LHC data. This report discusses the implementation and the computational aspects of the alignment and calibration framework. Recent commissioning campaigns with cosmic muons, beam halo and simulated data have been used to gain detailed experience with this framework, and results of this validation are reported.

Results on the calibration of the L3 BGO calorimeter with cosmic rays

International Nuclear Information System (INIS)

Bakken, J.A.; Barone, L.; Bay, A.; Blaising, J.J.; Borgia, B.; Bourilkov, D.; Boutigny, D.; Brock, I.C.; Buisson, C.; Capell, M.; Chaturvedi, U.K.; Chemarin, M.; Clare, R.; Coignet, G.; Denes, P.; DeNotaristefani, F.; Diemoz, M.; Duchesneau, D.; El Mamouni, H.; Extermann, P.; Fay, J.; Ferroni, F.; Gailloud, M.; Goujon, D.; Gratta, G.; Gupta, V.K.; Hilgers, K.; Ille, B.; Janssen, H.; Karyotakis, Y.; Kasser, A.; Kienzle-Focacci, M.N.; Krenz, W.; Lebrun, P.; Lecoq, P.; Leonardi, E.; Linde, F.L.; Lindemann, B.; Longo, E.; Lu, Y.S.; Luci, C.; Luckey, D.; Martin, J.P.; Merk, M.; Micke, M.; Morganti, S.; Newman, H.; Organtini, G.; Piroue, P.A.; Read, K.; Rosier-Lees, S.; Rosselet, P.; Sauvage, G.; Schmitz, D.; Schneegans, M.; Schwenke, J.; Stickland, D.P.; Tully, C.; Valente, E.; Vivargent, M.; Vuilleumier, L.; Wang, Y.F.; Weber, A.; Weill, R.; Wenninger, J.

1994-01-01

During 1991 two cosmic rays runs took place for the calibration of the L3 electromagnetic calorimeter. In this paper we present the results of the first high statistics cosmic ray calibration of the calorimeter in situ, including the end caps. Results show that the accuracy on the measurement of the calibration constants that can be achieved in one month of data taking is of 1.3%. (orig.)

BRDF Calibration of Sintered PTFE in the SWIR

Science.gov (United States)

Georgiev, Georgi T.; Butler, James J.

2009-01-01

Satellite instruments operating in the reflective solar wavelength region often require accurate and precise determination of the Bidirectional Reflectance Distribution Function (BRDF) of laboratory-based diffusers used in their pre-flight calibrations and ground-based support of on-orbit remote sensing instruments. The Diffuser Calibration Facility at NASA's Goddard Space Flight Center is a secondary diffuser calibration standard after NEST for over two decades, providing numerous NASA projects with BRDF data in the UV, Visible and the NIR spectral regions. Currently the Diffuser Calibration Facility extended the covered spectral range from 900 nm up to 1.7 microns. The measurements were made using the existing scatterometer by replacing the Si photodiode based receiver with an InGaAs-based one. The BRDF data was recorded at normal incidence and scatter zenith angles from 10 to 60 deg. Tunable coherent light source was setup. Broadband light source application is under development. Gray-scale sintered PTFE samples were used at these first trials, illuminated with P and S polarized incident light. The results are discussed and compared to empirically generated BRDF data from simple model based on 8 deg directional/hemispherical measurements.

Improved beam-energy calibration technique for heavy ion accelerators

International Nuclear Information System (INIS)

Ferrero, A.M.J.; Garcia, A.; Gil, Salvador

1989-01-01

A simple technique for beam energy calibration of heavy-ion accelerators is presented. A thin hydrogenous target was bombarded with 12 C and 19 F, and the energies of the protons knocked out, elastically were measured at several angles using two detectors placed at equal angles on opposite sides of the beam. The use of these two detectors cancels the largest errors due to uncertainties in the angle and position at which the beam hits the target. An application of this energy calibration method to an electrostatic accelerator is described and the calibration constant of the analyzing magnet was obtained with an estimated error of 0.4 (Author) [es

MIT wavelength tables. Volume 2. Wavelengths by element

International Nuclear Information System (INIS)

Phelps, F.M. III.

1982-01-01

This volume is the first stage of a project to expand and update the MIT wavelength tables first compiled in the 1930's. For 109,325 atomic emission lines, arranged by element, it presents wavelength in air, wavelength in vacuum, wave number and intensity. All data are stored on computer-readable magnetic tape

Hydrogen Balmer series measurements and determination of Rydberg's constant using two different spectrometers

International Nuclear Information System (INIS)

Amrani, D

2014-01-01

This paper investigates the use of two different methods, the optical and the computer-aided diffraction-grating spectrometer, to measure the wavelength of visible lines of Balmer series from the hydrogen atomic spectrum and estimate the value of Rydberg's constant. Analysis and interpretation of data showed that both methods, despite their difference in terms of the type of equipment used, displayed good performance in terms of precision of measurements of wavelengths of spectral lines. A comparison was carried out between the experimental value of Rydberg's constant obtained with both methods and the accepted value. The results of Rydberg's constant obtained with both the optical and computer-aided spectrometers were 1.099 28 × 10 −7  m −1  and 1.095 13 × 10 −7  m −1  with an error difference of 0.17% and 0.20% compared to the accepted value 1.097 373 × 10 −7  m −1 , respectively. (paper)

Monte Carlo calculations of calibrations of calibration coefficients of ATL monitors installed at NPP Temelin

International Nuclear Information System (INIS)

Solc, J.; Suran, J.; Novotna, M.; Pavlis, J.

2008-01-01

The contribution describes a technique of determination of calibration coefficients of a radioactivity monitor using Monte Carlo calculations. The monitor is installed at the NPP Temelin adjacent to lines with a radioactive medium. The output quantity is the activity concentration (in Bq/m3) that is converted from the number of counts per minute measured by the monitor. The value of this conversion constant, i.e. calibration coefficient, was calculated for gamma photons emitted by Co-60 and compared to the data stated by the manufacturer and supplier of these monitors, General Atomic Electronic Systems, Inc., USA. Results of the comparison show very good agreement between calculations and manufacturer data; the differences are lower than the quadratic sum of uncertainties. (authors)

Wavelength converter technology

DEFF Research Database (Denmark)

Kloch, Allan; Hansen, Peter Bukhave; Poulsen, Henrik Nørskov

1999-01-01

Wavelength conversion is important since it ensures full flexibility of the WDM network layer. Progress in optical wavelength converter technology is reviewed with emphasis on all-optical wavelength converter types based on semiconductor optical amplifiers.......Wavelength conversion is important since it ensures full flexibility of the WDM network layer. Progress in optical wavelength converter technology is reviewed with emphasis on all-optical wavelength converter types based on semiconductor optical amplifiers....

Calibration of Sn-119 isomer shift using ab initio wave function methods

NARCIS (Netherlands)

Kurian, Reshmi; Filatov, Michael

2009-01-01

The isomer shift for the 23.87 keV M1 resonant transition in the Sn-119 nucleus is calibrated with the help of ab initio calculations. The calibration constant alpha(Sn-119) obtained from Hartree-Fock (HF) calculations (alpha(HF)(Sn-119)=(0.081 +/- 0.002)a(0)(-3) mm/s) and from second-order

Integrated Wavelength-Tunable Light Source for Optical Gas Sensing Systems

Directory of Open Access Journals (Sweden)

Bin Li

2015-01-01

Full Text Available A compact instrument consisting of a distributed feedback laser (DFB at 1.65 μm was developed as a light source for gas sensing systems using tunable diode laser absorption spectroscopy (TDLAS technique. The wavelength of laser is tuned by adjusting the laser working temperature and injection current, which are performed by self-developed temperature controller and current modulator respectively. Stability test shows the fluctuation of the laser temperature is within the range of ±0.02°C. For gas detection experiments, the wavelength is tuned around the gas absorption line by adjusting laser temperature and is then shifted periodically to scan across the absorption line by the laser current modulator, which generates a 10 Hz saw wave signal. In addition, the current modulator is able to generate sine wave signal for gas sensing systems using wavelength modulation spectroscopy (WMS technique involving extraction of harmonic signals. The spectrum test proves good stability that the spectrum was measured 6 times every 10 minutes at the constant temperature and current condition. This standalone instrument can be applied as a light source for detection systems of different gases by integrating lasers at corresponding wavelength.

Calibration strategies for the Cherenkov Telescope Array

Science.gov (United States)

Gaug, Markus; Berge, David; Daniel, Michael; Doro, Michele; Förster, Andreas; Hofmann, Werner; Maccarone, Maria C.; Parsons, Dan; de los Reyes Lopez, Raquel; van Eldik, Christopher

2014-08-01

The Central Calibration Facilities workpackage of the Cherenkov Telescope Array (CTA) observatory for very high energy gamma ray astronomy defines the overall calibration strategy of the array, develops dedicated hardware and software for the overall array calibration and coordinates the calibration efforts of the different telescopes. The latter include LED-based light pulsers, and various methods and instruments to achieve a calibration of the overall optical throughput. On the array level, methods for the inter-telescope calibration and the absolute calibration of the entire observatory are being developed. Additionally, the atmosphere above the telescopes, used as a calorimeter, will be monitored constantly with state-of-the-art instruments to obtain a full molecular and aerosol profile up to the stratosphere. The aim is to provide a maximal uncertainty of 10% on the reconstructed energy-scale, obtained through various independent methods. Different types of LIDAR in combination with all-sky-cameras will provide the observatory with an online, intelligent scheduling system, which, if the sky is partially covered by clouds, gives preference to sources observable under good atmospheric conditions. Wide-field optical telescopes and Raman Lidars will provide online information about the height-resolved atmospheric extinction, throughout the field-of-view of the cameras, allowing for the correction of the reconstructed energy of each gamma-ray event. The aim is to maximize the duty cycle of the observatory, in terms of usable data, while reducing the dead time introduced by calibration activities to an absolute minimum.

Invited Article: Deep Impact instrument calibration.

Science.gov (United States)

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.

Invited Article: Deep Impact instrument calibration

International Nuclear Information System (INIS)

Klaasen, Kenneth P.; Mastrodemos, Nickolaos; A'Hearn, Michael F.; Farnham, Tony; Groussin, Olivier; Ipatov, Sergei; Li Jianyang; McLaughlin, Stephanie; Sunshine, Jessica; Wellnitz, Dennis; Baca, Michael; Delamere, Alan; Desnoyer, Mark; Thomas, Peter; Hampton, Donald; Lisse, Carey

2008-01-01

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 [∼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 ∼9 pixels. The charge coupled device (CCD) read noise is ∼1 DN. Electrical cross-talk between the CCD detector quadrants is correctable to <2 DN. The IR spectrometer response nonlinearity is correctable to ∼1%. Spectrometer read noise is ∼2 DN. The variation in zero-exposure signal level with time and spectrometer temperature is not fully characterized; currently corrections are good to ∼10 DN at best. Wavelength mapping onto the detector is known within 1 pixel; spectral lines have a FWHM of ∼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 ∼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.

Absolute calibration of a hydrogen discharge lamp in the vacuum ultraviolet

Science.gov (United States)

Nealy, J. E.

1975-01-01

A low-pressure hydrogen discharge lamp was calibrated for radiant intensity in the vacuum ultraviolet spectral region on an absolute basis and was employed as a laboratory standard source in spectrograph calibrations. This calibration was accomplished through the use of a standard photodiode detector obtained from the National Bureau of Standards together with onsite measurements of spectral properties of optical components used. The stability of the light source for use in the calibration of vacuum ultraviolet spectrographs and optical systems was investigated and found to be amenable to laboratory applications. The lamp was studied for a range of operating parameters; the results indicate that with appropriate peripheral instrumentation, the light source can be used as a secondary laboratory standard source when operated under preset controlled conditions. Absolute intensity measurements were recorded for the wavelengths 127.7, 158.0, 177.5, and 195.0 nm for a time period of over 1 month, and the measurements were found to be repeatable to within 11 percent.

Evolution of Altimetry Calibration and Future Challenges

Science.gov (United States)

Fu, Lee-Lueng; Haines, Bruce J.

2012-01-01

Over the past 20 years, altimetry calibration has evolved from an engineering-oriented exercise to a multidisciplinary endeavor driving the state of the art. This evolution has been spurred by the developing promise of altimetry to capture the large-scale, but small-amplitude, changes of the ocean surface containing the expression of climate change. The scope of altimeter calibration/validation programs has expanded commensurately. Early efforts focused on determining a constant range bias and verifying basic compliance of the data products with mission requirements. Contemporary investigations capture, with increasing accuracies, the spatial and temporal characteristics of errors in all elements of the measurement system. Dedicated calibration sites still provide the fundamental service of estimating absolute bias, but also enable long-term monitoring of the sea-surface height and constituent measurements. The use of a network of island and coastal tide gauges has provided the best perspective on the measurement stability, and revealed temporal variations of altimeter measurement system drift. The cross-calibration between successive missions provided fundamentally new information on the performance of altimetry systems. Spatially and temporally correlated errors pose challenges for future missions, underscoring the importance of cross-calibration of new measurements against the established record.

Efficient mass calibration of magnetic sector mass spectrometers

International Nuclear Information System (INIS)

Roddick, J.C.

1996-01-01

Magnetic sector mass spectrometers used for automatic acquisition of precise isotopic data are usually controlled with Hall probes and software that uses polynomial equations to define and calibrate the mass-field relations required for mass focusing. This procedure requires a number of reference masses and careful tuning to define and maintain an accurate mass calibration. A simplified equation is presented and applied to several different magnetically controlled mass spectrometers. The equation accounts for nonlinearity in typical Hall probe controlled mass-field relations, reduces calibration to a linear fitting procedure, and is sufficiently accurate to permit calibration over a mass range of 2 to 200 amu with only two defining masses. Procedures developed can quickly correct for normal drift in calibrations and compensate for drift during isotopic analysis over a limited mass range such as a single element. The equation is: Field A·Mass 1/2 + B·(Mass) p where A, B, and p are constants. The power value p has a characteristic value for a Hall probe/controller and is insensitive to changing conditions, thus reducing calibration to a linear regression to determine optimum A and B. (author). 1 ref., 1 tab., 6 figs

LHCb : Novel real-time alignment and calibration of the LHCb Detector in Run2

CERN Multimedia

Tobin, Mark

2015-01-01

LHCb has introduced a novel real-time detector alignment and calibration strategy for LHC Run 2. Data collected at the start of the fill will be processed in a few minutes and used to update the alignment, while the calibration constants will be evaluated for each run. This procedure will improve the quality of the online alignment. For example, the vertex locator is retracted and reinserted for stable beam collisions in each fill to be centred on the primary vertex position in the transverse plane. Consequently its position changes on a fill-by-fill basis. Critically, this new realtime alignment and calibration procedure allows identical constants to be used in the online and offline reconstruction, thus improving the correlation between triggered and offline selected events. This offers the opportunity to optimise the event selection in the trigger by applying stronger constraints. The online calibration facilitates the use of hadronic particle identification using the RICH detectors at the trigger level. T...

Calibration of ALIBAVA readout system

Energy Technology Data Exchange (ETDEWEB)

Trofymov, Artur [DESY, Hamburg (Germany); Collaboration: ATLAS experiment-Collaboration

2015-07-01

The High Luminosity Large Hadron Collider (LH-LHC) is the upgrade of the LHC that foreseen to increase the instantaneous luminosity by a factor ten with a total integrated luminosity of 3000 fb{sup -1}. The ATLAS experiment will need to build a new tracker to operate in the new severe LH-LHC conditions (increasing detector granularity to cope with much higher channel occupancy, designing radiation-hard sensors and electronics to cope with radiation damage). Charge collection efficiency (CCE) of silicon strip sensors for the new ATLAS tracker can be done with ALIBAVA analog readout system (analog system gives more information about signal from all strips than digital). In this work the preliminary results of ALIBAVA calibration using two different methods (with ''source data'' and ''calibration data'') are presented. Calibration constant obtained by these methods is necessary for knowing collected charge on the silicon strip sensors and for having the ability to compare it with measurements done at the test beam.

Sensitive Wavelengths Selection in Identification of Ophiopogon japonicus Based on Near-Infrared Hyperspectral Imaging Technology

Directory of Open Access Journals (Sweden)

Zhengyan Xia

2017-01-01

Full Text Available Hyperspectral imaging (HSI technology has increasingly been applied as an analytical tool in fields of agricultural, food, and Traditional Chinese Medicine over the past few years. The HSI spectrum of a sample is typically achieved by a spectroradiometer at hundreds of wavelengths. In recent years, considerable effort has been made towards identifying wavelengths (variables that contribute useful information. Wavelengths selection is a critical step in data analysis for Raman, NIRS, or HSI spectroscopy. In this study, the performances of 10 different wavelength selection methods for the discrimination of Ophiopogon japonicus of different origin were compared. The wavelength selection algorithms tested include successive projections algorithm (SPA, loading weights (LW, regression coefficients (RC, uninformative variable elimination (UVE, UVE-SPA, competitive adaptive reweighted sampling (CARS, interval partial least squares regression (iPLS, backward iPLS (BiPLS, forward iPLS (FiPLS, and genetic algorithms (GA-PLS. One linear technique (partial least squares-discriminant analysis was established for the evaluation of identification. And a nonlinear calibration model, support vector machine (SVM, was also provided for comparison. The results indicate that wavelengths selection methods are tools to identify more concise and effective spectral data and play important roles in the multivariate analysis, which can be used for subsequent modeling analysis.

Calibration of Relative Humidity Sensors using a Dew Point Generator

OpenAIRE

Brooks, Milo

2010-01-01

A relative humidity sensor can be calibrated using a dew point generator to continuously supply an air stream of known constant humidity and a temperature chamber to control the dew point and ambient temperature.

Michelson Interferometer for Global High-Resolution Thermospheric Imaging (MIGHTI): Instrument Design and Calibration

Science.gov (United States)

Englert, Christoph R.; Harlander, John M.; Brown, Charles M.; Marr, Kenneth D.; Miller, Ian J.; Stump, J. Eloise; Hancock, Jed; Peterson, James Q.; Kumler, Jay; Morrow, William H.; Mooney, Thomas A.; Ellis, Scott; Mende, Stephen B.; Harris, Stewart E.; Stevens, Michael H.; Makela, Jonathan J.; Harding, Brian J.; Immel, Thomas J.

2017-10-01

The Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) instrument was built for launch and operation on the NASA Ionospheric Connection Explorer (ICON) mission. The instrument was designed to measure thermospheric horizontal wind velocity profiles and thermospheric temperature in altitude regions between 90 km and 300 km, during day and night. For the wind measurements it uses two perpendicular fields of view pointed at the Earth's limb, observing the Doppler shift of the atomic oxygen red and green lines at 630.0 nm and 557.7 nm wavelength. The wavelength shift is measured using field-widened, temperature compensated Doppler Asymmetric Spatial Heterodyne (DASH) spectrometers, employing low order échelle gratings operating at two different orders for the different atmospheric lines. The temperature measurement is accomplished by a multichannel photometric measurement of the spectral shape of the molecular oxygen A-band around 762 nm wavelength. For each field of view, the signals of the two oxygen lines and the A-band are detected on different regions of a single, cooled, frame transfer charge coupled device (CCD) detector. On-board calibration sources are used to periodically quantify thermal drifts, simultaneously with observing the atmosphere. The MIGHTI requirements, the resulting instrument design and the calibration are described.

Upgrading the Medical Physics Calibration Laboratory Towards ISO/IEC 17025: Radiation Standards and Calibration in Diagnostic Radiology

International Nuclear Information System (INIS)

Asmaliza Hashim; Muhammad Jamal Md Isa; Abd Aziz Mhd Ramli; Wan Hazlinda Ismail; Norhayati Abdullah; Shahrul Azlan Azizan; Siti Sara Deraman; Nor Azlin Azraai; Md Khairusalih Md Zin

2010-01-01

Calibration of quality control (QC) test tools used in diagnostic radiology is legally required under the Ministry of Health (MOH) requirement. The Medical Physics Calibration Laboratory of the Malaysian Nuclear Agency is the national focal point for the calibration of quality control test tools used in diagnostic radiology. The Medical Physics Calibration Laboratory has measurement traceability to primary standard dosimetry laboratory (Physikalisch-Technische Bundesanstalt (PTB)), thus providing an interface between the primary standard dosimetry laboratory and Malaysian hospitals, clinics and license class H holder. The Medical Physics Calibration Laboratory facility is comprised of a constant potential x-ray system with a capability of 160 kV tube and a series of reference and working standard ion chambers. The stability of reference and working standard ion chambers was measured using strontium-90. Dosimetric instruments used in diagnostic radiology is calibrated in terms of air kerma to comply with an International Code of Practices of dosimetry for example IAEA's Technical Report Series number 457. The new series of standard radiation qualities was established based on ISO/IEC 61267. The measurement of beam homogeneity was measured using film and ion chamber to define the field size at certain distance and kV output was measured using the spectrometer and non-invasive kVp meter. The uncertainties measurement was determined with expended uncertainties to a level of confidence of approximately 95% (coverage factor k=2). This paper describes the available facility and the effort of the Medical Physics Calibration Laboratory to upgrade the laboratory towards ISO/IEC 17025. (author)

The calibration of spectrometers for Auger electron and X-ray photoelectron spectrometers part I - an absolute traceable energy calibration for electron spectrometers

International Nuclear Information System (INIS)

Smith, G.C.; Seah, M.P.; Anthony, M.T.

1991-01-01

Experiments have been made to provide calibrated kinetic energy values for AES peaks in order to calibrate Auger electron spectrometers of various resolving powers. The kinetic energies are measured using a VG Scientific ESCALAB 2 which has power supplies appropriate for AES measurements in both the constant ΔE and constant ΔE/E modes. The absolute calibration of the energy scale is obtained by the development of a new measurement chain which, in turn, is calibrated in terms of the post-1990 representation of electron volts using XPS peaks with a traceable kinetic energy accuracy of 0.02 eV. The effects of instrumental and operating parameters, including the spectrometer dispersion and stray magnetic fields, are all assessed and contribute errors for three peaks not exceeding 0.06 eV and for two peaks not exceeding 0.03 eV. Calibrated positions in the direct spectrum are given for the Cu M 2,3 VV, Au N 6,7 VV, Ag M 4 NN, Cu L 3 VV and Au M 5 N 6,7 N 6,7 transitions at 0.2 eV resolution, referred to both the Standard Vacuum Level and the Fermi level. For the derivative spectrum the positions of the negative excursions are derived numerically by computer from this data and are established with the same accuracy. Data are tabulated for the above peaks in both the direct and differentiated modes for the popular resolutions of 0.15%, 0.3% and 0.6% produced by Gaussian broadening of the high resolution spectra. Differentiations are effected by both sinusoidal modulation and Savitzky-Golay functions of 2 eV and 5 eV peak-to-peak

Rapid and accurate control rod calibration measurement and analysis

International Nuclear Information System (INIS)

Nelson, George W.; Doane, Harry J.

1990-01-01

In order to reduce the time needed to perform control rod calibrations and improve the accuracy of the results, a technique for a measurement, analysis, and tabulation of integral rod worths has been developed. A single series of critical rod positions are determined at constant low power to reduce the waiting time between positive period measurements and still assure true stable reactor period data. Reactivity values from positive period measurements and control rod drop measurements are used as input data for a non-linear fit to the expected control rod integral worth shape. With this method, two control rods can be calibrated in about two hours, and integral and differential calibration tables for operator use are printed almost immediately. Listings of the BASIC computer programs for the non-linear fitting and calibration table preparation are provided. (author)

Effect of the wavelength on laser induced breakdown spectrometric analysis of archaeological bone

Energy Technology Data Exchange (ETDEWEB)

Kasem, M.A. [National Institute of Laser Enhanced Science (NILES), Cairo University, Giza (Egypt); Gonzalez, J.J.; Russo, R.E. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Harith, M.A., E-mail: mharithm@niles.edu.eg [National Institute of Laser Enhanced Science (NILES), Cairo University, Giza (Egypt)

2014-11-01

The analytical exploitation of the laser induced plasma suffers from its transient behavior due to some nonlinear effects. These phenomena are matrix-dependent and limit the use of LIBS to mostly semi-quantitative precision. The plasma parameters have to be kept as constant as possible during LIBS measurements. Studying archaeological bone samples using LIBS technique could be more difficult since these samples are less tough in their texture than many other solid samples. Thus, the ablation process could change the sample morphological features rapidly resulting in poor reproducibility and statistics. Furthermore archaeological bones are subjected to diagenesis effects due to burial environment and postmortem effects. In the present work comparative analytical study of UV (266 nm) and IR (1064 nm) LIBS for archaeological bone samples belonging to four ancient Egyptian dynasties representing the middle kingdom (1980–1630 BC), 2nd intermediate period (1630–1539/23 BC), Roman–Greek period (30 BC–A.D. 395) and the late period (664–332 BC). Measurements have been performed under identical experimental conditions except the laser wavelength to examine its effects. Elemental fluctuations within the same dynasty were studied for reliable information about each dynasty. The analytical results demonstrated that UV-LIBS gives a more realistic picture for bone elemental composition within the same dynasty, and bone ash could be more suitable as a reference material for bone calibration in the case of UV-LIBS. - Highlights: • UV and IR LIBS for archaeological bone samples have been performed. • Elemental fluctuations within the same dynasty were studied. • UV-LIBS gave realistic picture for bone elemental composition for the same dynasty. • Depth profile for Sr/Ca concentration was an indicator for the diagenesis effect. • Bone ash is the most suitable for calcified tissue calibration for UV-LIBS.

Effect of the wavelength on laser induced breakdown spectrometric analysis of archaeological bone

International Nuclear Information System (INIS)

Kasem, M.A.; Gonzalez, J.J.; Russo, R.E.; Harith, M.A.

2014-01-01

The analytical exploitation of the laser induced plasma suffers from its transient behavior due to some nonlinear effects. These phenomena are matrix-dependent and limit the use of LIBS to mostly semi-quantitative precision. The plasma parameters have to be kept as constant as possible during LIBS measurements. Studying archaeological bone samples using LIBS technique could be more difficult since these samples are less tough in their texture than many other solid samples. Thus, the ablation process could change the sample morphological features rapidly resulting in poor reproducibility and statistics. Furthermore archaeological bones are subjected to diagenesis effects due to burial environment and postmortem effects. In the present work comparative analytical study of UV (266 nm) and IR (1064 nm) LIBS for archaeological bone samples belonging to four ancient Egyptian dynasties representing the middle kingdom (1980–1630 BC), 2nd intermediate period (1630–1539/23 BC), Roman–Greek period (30 BC–A.D. 395) and the late period (664–332 BC). Measurements have been performed under identical experimental conditions except the laser wavelength to examine its effects. Elemental fluctuations within the same dynasty were studied for reliable information about each dynasty. The analytical results demonstrated that UV-LIBS gives a more realistic picture for bone elemental composition within the same dynasty, and bone ash could be more suitable as a reference material for bone calibration in the case of UV-LIBS. - Highlights: • UV and IR LIBS for archaeological bone samples have been performed. • Elemental fluctuations within the same dynasty were studied. • UV-LIBS gave realistic picture for bone elemental composition for the same dynasty. • Depth profile for Sr/Ca concentration was an indicator for the diagenesis effect. • Bone ash is the most suitable for calcified tissue calibration for UV-LIBS

Stability of short-axial-wavelength internal kink modes of an anisotropic plasma

Science.gov (United States)

Faghihi, M.; Scheffel, J.

1987-12-01

The double adiabatic equations are used to study the stability of a cylindrical Z-pinch with respect to small axial wavelength, internal kink (m ≥ 1) modes. It is found that marginally (ideally) unstable, isotropic equilibria are stabilized. Also, constant-current-density equilibria can be stabilized for P > P and large β

CMS Alignement and Calibration workflows: lesson learned and future plans

CERN Document Server

AUTHOR|(CDS)2069172

2014-01-01

We review the online and offline workflows designed to align and calibrate the CMS detector. Starting from the gained experience during the first LHC run, we discuss the expected developments for Run II. In particular, we describe the envisioned different stages, from the alignment using cosmic rays data to the detector alignment and calibration using the first proton-proton collisions data ( O(100 pb-1) ) and a larger dataset ( O(1 fb-1) ) to reach the target precision. The automatisation of the workflow and the integration in the online and offline activity (dedicated triggers and datasets, data skims, workflows to compute the calibration and alignment constants) are discussed.

Identification of solid state fermentation degree with FT-NIR spectroscopy: Comparison of wavelength variable selection methods of CARS and SCARS

Science.gov (United States)

Jiang, Hui; Zhang, Hang; Chen, Quansheng; Mei, Congli; Liu, Guohai

2015-10-01

The use of wavelength variable selection before partial least squares discriminant analysis (PLS-DA) for qualitative identification of solid state fermentation degree by FT-NIR spectroscopy technique was investigated in this study. Two wavelength variable selection methods including competitive adaptive reweighted sampling (CARS) and stability competitive adaptive reweighted sampling (SCARS) were employed to select the important wavelengths. PLS-DA was applied to calibrate identified model using selected wavelength variables by CARS and SCARS for identification of solid state fermentation degree. Experimental results showed that the number of selected wavelength variables by CARS and SCARS were 58 and 47, respectively, from the 1557 original wavelength variables. Compared with the results of full-spectrum PLS-DA, the two wavelength variable selection methods both could enhance the performance of identified models. Meanwhile, compared with CARS-PLS-DA model, the SCARS-PLS-DA model achieved better results with the identification rate of 91.43% in the validation process. The overall results sufficiently demonstrate the PLS-DA model constructed using selected wavelength variables by a proper wavelength variable method can be more accurate identification of solid state fermentation degree.

Step-edge calibration of torsional sensitivity for lateral force microscopy

International Nuclear Information System (INIS)

Sul, Onejae; Jang, Seongjin; Yang, Eui-Hyeok

2009-01-01

A novel calibration technique has been developed for lateral force microscopy (LFM). Typically, special preparation of the atomic force microscope (AFM) cantilever or a substrate is required for LFM calibration. The new calibration technique reported in this paper greatly reduces the required preparation processes by simply scanning over a rigid step and measuring the response of the AFM photodiode in the normal and lateral directions. When an AFM tip touches a step while scanning, the tip experiences a reaction force from the step edge, and the amount of torsion can be estimated based on the ratio of the normal and torsional spring constants of an AFM cantilever. Therefore, the torsion can be calibrated using the measured response of the photodiode from the lateral movement of the AFM tip. This new calibration technique has been tested and confirmed by measuring Young's modulus of a nickel (Ni) nanowire

The design and realization of calibration apparatus for measuring the concentration of radon in three models

Energy Technology Data Exchange (ETDEWEB)

Huiping, Guo [The Second Artillery Engineering College, Xi' an (China)

2007-06-15

For satisfying calibration request of radon measure in the laboratory, the calibration apparatus for radon activity measure is designed and realized. The calibration apparatus can auto-control and auto-measure in three models. sequent mode, pulse mode and constant mode. The stability and reliability of the calibration apparatus was tested under the three models. The experimental result shows that the apparatus can provides an adjustable and steady radon activity concentration environment for the research of radon and its progeny and for the calibration of its measure. (authors)

Self-calibration in optical/infrared interferometry

Science.gov (United States)

Millour, Florentin; Dalla Vedova, Gaetan

2015-08-01

Optical interferometry produces nowadays images of the observed stars. However, the image quality of the current facilities (VLTI, CHARA) is impaired by the lack of phases measurements. We will describe here a method used to improve the image reconstruction that takes profit of a badly used observable: the wavelength differential phase. This phase shares some properties with the interferometric phase. That method is parent to the self-calibration which was developed in the 80's for radio astronomy to get rid of calibratioon artifacts, and produces a significant improvement on image quality over the current available methods.

Multispectral calibration to enhance the metrology performance of C-mount camera systems

Directory of Open Access Journals (Sweden)

S. Robson

2014-06-01

Full Text Available Low cost monochrome camera systems based on CMOS sensors and C-mount lenses have been successfully applied to a wide variety of metrology tasks. For high accuracy work such cameras are typically equipped with ring lights to image retro-reflective targets as high contrast image features. Whilst algorithms for target image measurement and lens modelling are highly advanced, including separate RGB channel lens distortion correction, target image circularity compensation and a wide variety of detection and centroiding approaches, less effort has been directed towards optimising physical target image quality by considering optical performance in narrow wavelength bands. This paper describes an initial investigation to assess the effect of wavelength on camera calibration parameters for two different camera bodies and the same ‘C-mount’ wide angle lens. Results demonstrate the expected strong influence on principal distance, radial and tangential distortion, and also highlight possible trends in principal point, orthogonality and affinity parameters which are close to the parameter estimation noise level from the strong convergent self-calibrating image networks.

Stability of small axial wavelength internal kink modes of an anisotropic plasma

International Nuclear Information System (INIS)

Faghihi, M.; Scheffel, J.

1987-03-01

The double adiabatic equations are used to study the stability of a cylindrical Z-pinch with respect to small axial wavelength, internal kink (m>=1)modes. It is found that marginally (ideally) unstable, isotropic equilibria are stabilized. Also constant current density equilibria can be stabilized for P per >P par and large β per . (authors)

Calibration and intercomparison methods of dose calibrators used in nuclear medicine facilities; Metodos de calibracao e de intercomparacao de calibradores de dose utilizados em servicos de medicina nuclear

Energy Technology Data Exchange (ETDEWEB)

Costa, Alessandro Martins da

1999-07-01

Dose calibrators are used in most of the nuclear medicine facilities to determine the amount of radioactivity administered to a patient in a particular investigation or therapeutic procedure. It is therefore of vital importance that the equipment used presents good performance and is regular;y calibrated at a authorized laboratory. This occurs of adequate quality assurance procedures are carried out. Such quality control tests should be performed daily, other biannually or yearly, testing, for example, its accuracy and precision, the reproducibility and response linearity. In this work a commercial dose calibrator was calibrated with solution of radionuclides used in nuclear medicine. Simple instrument tests, such as response linearity and the response variation of the source volume increase at a constant source activity concentration, were performed. This instrument can now be used as a working standard for calibration of other dose calibrators/ An intercomparison procedure was proposed as a method of quality control of dose calibrators used in nuclear medicine facilities. (author)

POLCAL - POLARIMETRIC RADAR CALIBRATION

Science.gov (United States)

Vanzyl, J.

1994-01-01

Calibration of polarimetric radar systems is a field of research in which great progress has been made over the last few years. POLCAL (Polarimetric Radar Calibration) is a software tool intended to assist in the calibration of Synthetic Aperture Radar (SAR) systems. In particular, POLCAL calibrates Stokes matrix format data produced as the standard product by the NASA/Jet Propulsion Laboratory (JPL) airborne imaging synthetic aperture radar (AIRSAR). POLCAL was designed to be used in conjunction with data collected by the NASA/JPL AIRSAR system. AIRSAR is a multifrequency (6 cm, 24 cm, and 68 cm wavelength), fully polarimetric SAR system which produces 12 x 12 km imagery at 10 m resolution. AIRSTAR was designed as a testbed for NASA's Spaceborne Imaging Radar program. While the images produced after 1991 are thought to be calibrated (phase calibrated, cross-talk removed, channel imbalance removed, and absolutely calibrated), POLCAL can and should still be used to check the accuracy of the calibration and to correct it if necessary. Version 4.0 of POLCAL is an upgrade of POLCAL version 2.0 released to AIRSAR investigators in June, 1990. New options in version 4.0 include automatic absolute calibration of 89/90 data, distributed target analysis, calibration of nearby scenes with calibration parameters from a scene with corner reflectors, altitude or roll angle corrections, and calibration of errors introduced by known topography. Many sources of error can lead to false conclusions about the nature of scatterers on the surface. Errors in the phase relationship between polarization channels result in incorrect synthesis of polarization states. Cross-talk, caused by imperfections in the radar antenna itself, can also lead to error. POLCAL reduces cross-talk and corrects phase calibration without the use of ground calibration equipment. Removing the antenna patterns during SAR processing also forms a very important part of the calibration of SAR data. Errors in the

Efficient mass calibration of magnetic sector mass spectrometers

Energy Technology Data Exchange (ETDEWEB)

Roddick, J C

1997-12-31

Magnetic sector mass spectrometers used for automatic acquisition of precise isotopic data are usually controlled with Hall probes and software that uses polynomial equations to define and calibrate the mass-field relations required for mass focusing. This procedure requires a number of reference masses and careful tuning to define and maintain an accurate mass calibration. A simplified equation is presented and applied to several different magnetically controlled mass spectrometers. The equation accounts for nonlinearity in typical Hall probe controlled mass-field relations, reduces calibration to a linear fitting procedure, and is sufficiently accurate to permit calibration over a mass range of 2 to 200 amu with only two defining masses. Procedures developed can quickly correct for normal drift in calibrations and compensate for drift during isotopic analysis over a limited mass range such as a single element. The equation is: Field A{center_dot}Mass{sup 1/2} + B{center_dot}(Mass){sup p} where A, B, and p are constants. The power value p has a characteristic value for a Hall probe/controller and is insensitive to changing conditions, thus reducing calibration to a linear regression to determine optimum A and B. (author). 1 ref., 1 tab., 6 figs.

The Pelindaba facility for calibrating radiometric field instruments

International Nuclear Information System (INIS)

Corner, B.; Toens, P.D.; Van As, D.; Vleggaar, C.M.; Richards, D.J.

1979-04-01

The tremendous upsurge in uranium exploration activity, experienced in recent years, has made the need for the standardisation and calibration of radiometric field instruments apparent. In order to fulfill this need, construction of a calibration facility at the National Nuclear Research Centre, Pelindaba, was commenced in 1972 and has since been extended according the the requirements of the mining industry. The facility currently comprises 11 surface standard sources suitable for the calibration, in terms of radio-element concentration, of portable scintillometers and spectrometers, and single uranium and thorium model-borehole sources which make possible the accurate calibration of borehole logging instruments both for gross-count and spectrometric surveys. Portable potassium, uranium and thorium sources are also available for the purposes of establishing airborne-spectrometer stripping ratios. The relevant physico-chemical properties of the standards are presented in this report and calibration procedures and data reduction techniques recommended. Examples are given of in situ measurements, both on surface and down-the-hole, which show that the derived calibration constants yield radiometric grades which are, on average, accurate to within 5% of the true radio-element concentrations. A secondary facility comprising single borehole- and surface-uranium sources has also been constructed in Beaufort West in the southern Karoo [af

IACHEC CROSS-CALIBRATION OF CHANDRA , NuSTAR , SWIFT , SUZAKU , XMM-NEWTON WITH 3C 273 ANDPKS 2155-304

Energy Technology Data Exchange (ETDEWEB)

Madsen, Kristin K.; Forster, Karl [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Beardmore, Andrew P.; Page, Kim L. [X-ray and Observational Astronomy Group, Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH (United Kingdom); Guainazzi, Matteo [Japan Aerospace Exploration Agency, Institute of Space and Astronautical Science, 3-1-1, Yoshinodai, Sagamihara, Kanagawa, 252-5201 (Japan); Marshall, Herman L.; Miller, Eric D. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 (United States); Stuhlinger, Martin [European Space Astronomy Centre (ESAC), P.O. Box 78, E-28691 Villanueva de la Caada, Madrid (Spain)

2017-01-01

On behalf of the International Astronomical Consortium for High Energy Calibration, we present results from the cross-calibration campaigns in 2012 on 3C 273 and in 2013 on PKS 2155-304 between the then active X-ray observatories Chandra , NuSTAR , Suzaku , Swift, and XMM-Newton . We compare measured fluxes between instrument pairs in two energy bands, 1–5 keV and 3–7 keV, and calculate an average cross-normalization constant for each energy range. We review known cross-calibration features and provide a series of tables and figures to be used for evaluating cross-normalization constants obtained from other observations with the above mentioned observatories.

Stability of short-axial-wavelength internal kink modes of an anisotropic plasma

International Nuclear Information System (INIS)

Faghihi, M.; Schefffel, J.

1987-01-01

The double adiabatic equations are used to study the stability of a cylindrical Z-pinch with respect to small axial wavelength, internal kink (m ≥ 1) modes. It is found that marginally (ideally) unstable, isotropic equilibria are stabilized. Also, constant-current-density equilibria can be stabilized for Psub(perpendicular) > Psub(parallel) and large βsub(perpendicular). (author)

SARAS MEASUREMENT OF THE RADIO BACKGROUND AT LONG WAVELENGTHS

International Nuclear Information System (INIS)

Patra, Nipanjana; Subrahmanyan, Ravi; Sethi, Shiv; Shankar, N. Udaya; Raghunathan, A.

2015-01-01

SARAS is a correlation spectrometer connected to a frequency independent antenna that is purpose-designed for precision measurements of the radio background at long wavelengths. The design, calibration, and observing strategies admit solutions for the internal additive contributions to the radiometer response, and hence a separation of these contaminants from the antenna temperature. We present here a wideband measurement of the radio sky spectrum by SARAS that provides an accurate measurement of the absolute brightness and spectral index between 110 and 175 MHz. Accuracy in the measurement of absolute sky brightness is limited by systematic errors of magnitude 1.2%; errors in calibration and in the joint estimation of sky and system model parameters are relatively smaller. We use this wide-angle measurement of the sky brightness using the precision wide-band dipole antenna to provide an improved absolute calibration for the 150 MHz all-sky map of Landecker and Wielebinski: subtracting an offset of 21.4 K and scaling by a factor of 1.05 will reduce the overall offset error to 8 K (from 50 K) and scale error to 0.8% (from 5%). The SARAS measurement of the temperature spectral index is in the range −2.3 to −2.45 in the 110–175 MHz band and indicates that the region toward the Galactic bulge has a relatively flatter index

Comparison of Mg-based multilayers for solar He II radiation at 30.4 nm wavelength

Energy Technology Data Exchange (ETDEWEB)

Zhu Jingtao; Zhou Sika; Li Haochuan; Huang Qiushi; Wang Zhanshan; Le Guen, Karine; Hu, Min-Hui; Andre, Jean-Michel; Jonnard, Philippe

2010-07-10

Mg-based multilayers, including SiC/Mg, Co/Mg, B4C/Mg, and Si/Mg, are investigated for solar imaging and a He II calibration lamp at a 30.4 nm wavelength. These multilayers were fabricated by a magnetron sputtering method and characterized by x-ray reflection. The reflectivities of these multilayers were measured by synchrotron radiation. Near-normal-incidence reflectivities of Co/Mg and SiC/Mg multilayer mirrors are as high as 40.3% and 44.6%, respectively, while those of B4C/Mg and Si/Mg mirrors are too low for application. The measured results suggest that SiC/Mg, Co/Mg multilayers are promising for a 30.4 nm wavelength.

A fast dual wavelength laser beam fluid-less optical CT scanner for radiotherapy 3D gel dosimetry II: dosimetric performance

Science.gov (United States)

Ramm, Daniel

2018-02-01

New clinical radiotherapy dosimetry systems need comprehensive demonstration of measurement quality. Practicality and reliability are other important aspects for clinical dosimeters. In this work the performance of an optical CT scanner for true 3D dosimetry is assessed using a radiochromic gel dosimeter. The fluid-less scanner utilised dual lasers to avoid the necessity for pre-irradiation scans and give greater robustness of image quality, enhancing practicality. Calibration methods using both cuvettes and reconstructed volumes were developed. Dosimetric accuracy was similar for dual and single wavelength measurements, except that cuvette calibration reliability was reduced for dual wavelength without pre-irradiation scanning. Detailed performance parameters were specified for the dosimetry system indicating the suitability for clinical use. The most significant limitations of the system were due to the gel dosimeter rather than the optical CT scanner. Quality assurance guidelines were developed to maintain dosimetry system performance in routine use.

Calibration factor or calibration coefficient?

International Nuclear Information System (INIS)

Meghzifene, A.; Shortt, K.R.

2002-01-01

Full text: The IAEA/WHO network of SSDLs was set up in order to establish links between SSDL members and the international measurement system. At the end of 2001, there were 73 network members in 63 Member States. The SSDL network members provide calibration services to end-users at the national or regional level. The results of the calibrations are summarized in a document called calibration report or calibration certificate. The IAEA has been using the term calibration certificate and will continue using the same terminology. The most important information in a calibration certificate is a list of calibration factors and their related uncertainties that apply to the calibrated instrument for the well-defined irradiation and ambient conditions. The IAEA has recently decided to change the term calibration factor to calibration coefficient, to be fully in line with ISO [ISO 31-0], which recommends the use of the term coefficient when it links two quantities A and B (equation 1) that have different dimensions. The term factor should only be used for k when it is used to link the terms A and B that have the same dimensions A=k.B. However, in a typical calibration, an ion chamber is calibrated in terms of a physical quantity such as air kerma, dose to water, ambient dose equivalent, etc. If the chamber is calibrated together with its electrometer, then the calibration refers to the physical quantity to be measured per electrometer unit reading. In this case, the terms referred have different dimensions. The adoption by the Agency of the term coefficient to express the results of calibrations is consistent with the 'International vocabulary of basic and general terms in metrology' prepared jointly by the BIPM, IEC, ISO, OIML and other organizations. The BIPM has changed from factor to coefficient. The authors believe that this is more than just a matter of semantics and recommend that the SSDL network members adopt this change in terminology. (author)

Ground-based measurements of the 1.3 to 0.3 millimeter spectrum of Jupiter and Saturn, and their detailed calibration.

Science.gov (United States)

Pardo, Juan R; Serabyn, Eugene; Wiedner, Martina C; Moreno, Raphäel; Orton, Glenn

2017-07-01

One of the legacies of the now retired Caltech Submillimeter Observatory (CSO) is presented in this paper. We measured for the first time the emission of the giant planets Jupiter and Saturn across the 0.3 to 1.3 mm wavelength range using a Fourier Transform Spectrometer mounted on the 10.4-meter dish of the CSO at Mauna Kea, Hawaii, 4100 meters above sea level. A careful calibration, including the evaluation of the antenna performance over such a wide wavelength range and the removal of the Earth's atmosphere effects, has allowed the detection of broad absorption lines on those planets' atmospheres. The calibrated data allowed us to verify the predictions of standard models for both planets in this spectral region, and to confirm the absolute radiometry in the case of Jupiter. Besides their physical interest, the results are also important as both planets are calibration references in the current era of operating ground-based and space-borne submillimeter instruments.

Ground-based measurements of the 1.3 to 0.3 mm spectrum of Jupiter and Saturn, and their detailed calibration

Science.gov (United States)

Pardo, Juan R.; Serabyn, Eugene; Wiedner, Martina C.; Moreno, Raphäel; Orton, Glenn

2017-07-01

One of the legacies of the now retired Caltech Submillimeter Observatory (CSO) is presented in this paper. We measured for the first time the emission of the giant planets Jupiter and Saturn across the 0.3 to 1.3 mm wavelength range using a Fourier Transform Spectrometer mounted on the 10.4 m dish of the CSO at Mauna Kea, Hawaii, 4100 m above sea level. A careful calibration, including the evaluation of the antenna performance over such a wide wavelength range and the removal of the Earth's atmosphere effects, has allowed the detection of broad absorption lines on those planets' atmospheres. The calibrated data allowed us to verify the predictions of standard models for both planets in this spectral region, and to confirm the absolute radiometry in the case of Jupiter. Besides their physical interest, the results are also important as both planets are calibration references in the current era of operating ground-based and space-borne submillimeter instruments.

On Inertial Body Tracking in the Presence of Model Calibration Errors.

Science.gov (United States)

Miezal, Markus; Taetz, Bertram; Bleser, Gabriele

2016-07-22

In inertial body tracking, the human body is commonly represented as a biomechanical model consisting of rigid segments with known lengths and connecting joints. The model state is then estimated via sensor fusion methods based on data from attached inertial measurement units (IMUs). This requires the relative poses of the IMUs w.r.t. the segments-the IMU-to-segment calibrations, subsequently called I2S calibrations-to be known. Since calibration methods based on static poses, movements and manual measurements are still the most widely used, potentially large human-induced calibration errors have to be expected. This work compares three newly developed/adapted extended Kalman filter (EKF) and optimization-based sensor fusion methods with an existing EKF-based method w.r.t. their segment orientation estimation accuracy in the presence of model calibration errors with and without using magnetometer information. While the existing EKF-based method uses a segment-centered kinematic chain biomechanical model and a constant angular acceleration motion model, the newly developed/adapted methods are all based on a free segments model, where each segment is represented with six degrees of freedom in the global frame. Moreover, these methods differ in the assumed motion model (constant angular acceleration, constant angular velocity, inertial data as control input), the state representation (segment-centered, IMU-centered) and the estimation method (EKF, sliding window optimization). In addition to the free segments representation, the optimization-based method also represents each IMU with six degrees of freedom in the global frame. In the evaluation on simulated and real data from a three segment model (an arm), the optimization-based method showed the smallest mean errors, standard deviations and maximum errors throughout all tests. It also showed the lowest dependency on magnetometer information and motion agility. Moreover, it was insensitive w.r.t. I2S position and

Trigger Algorithms for Alignment and Calibration at the CMS Experiment

CERN Document Server

Fernandez Perez Tomei, Thiago Rafael

2017-01-01

The data needs of the Alignment and Calibration group at the CMS experiment are reasonably different from those of the physics studies groups. Data are taken at CMS through the online event selection system, which is implemented in two steps. The Level-1 Trigger is implemented on custom-made electronics and dedicated to analyse the detector information at a coarse-grained scale, while the High Level Trigger (HLT) is implemented as a series of software algorithms, running in a computing farm, that have access to the full detector information. In this paper we describe the set of trigger algorithms that is deployed to address the needs of the Alignment and Calibration group, how it fits in the general infrastructure of the HLT, and how it feeds the Prompt Calibration Loop (PCL), allowing for a fast turnaround for the alignment and calibration constants.

Novel real-time alignment and calibration of the LHCb detector in Run2

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00144085

2017-01-01

LHCb has introduced a novel real-time detector alignment and calibration strategy for LHC Run2. Data collected at the start of the fill are processed in a few minutes and used to update the alignment parameters, while the calibration constants are evaluated for each run. This procedure improves the quality of the online reconstruction. For example, the vertex locator is retracted and reinserted for stable beam conditions in each fill to be centred on the primary vertex position in the transverse plane. Consequently its position changes on a fill-by-fill basis. Critically, this new real-time alignment and calibration procedure allows identical constants to be used in the online and offline reconstruction, thus improving the correlation between triggered and offline-selected events. This offers the opportunity to optimise the event selection in the trigger by applying stronger constraints. The required computing time constraints are met thanks to a new dedicated framework using the multi-core farm infrastructur...

Planck 2013 results. V. LFI calibration

CERN Document Server

Aghanim, N; Arnaud, M; Ashdown, M; Atrio-Barandela, F; Aumont, J; Baccigalupi, C; Banday, A J; Barreiro, R B; Battaner, E; Benabed, K; Benoît, A; Benoit-Lévy, A; Bernard, J -P; Bersanelli, M; Bielewicz, P; Bobin, J; Bock, J J; Bonaldi, A; Bonavera, L; Bond, J R; Borrill, J; Bouchet, F R; Bridges, M; Bucher, M; Burigana, C; Butler, R C; Cappellini, B; Cardoso, J -F; Catalano, A; Chamballu, A; Chen, X; Chiang, L -Y; Christensen, P R; Church, S; Colombi, S; Colombo, L P L; Crill, B P; Curto, A; Cuttaia, F; Danese, L; Davies, R D; Davis, R J; de Bernardis, P; de Rosa, A; de Zotti, G; Delabrouille, J; Dickinson, C; Diego, J M; Dole, H; Donzelli, S; Doré, O; Douspis, M; Dupac, X; Efstathiou, G; Enßlin, T A; Eriksen, H K; Finelli, F; Forni, O; Frailis, M; Franceschi, E; Gaier, T C; Galeotta, S; Ganga, K; Giard, M; Giardino, G; Giraud-Héraud, Y; Gjerløw, E; González-Nuevo, J; Górski, K M; Gratton, S; Gregorio, A; Gruppuso, A; Hansen, F K; Hanson, D; Harrison, D; Henrot-Versillé, S; Hernández-Monteagudo, C; Herranz, D; Hildebrandt, S R; Hivon, E; Hobson, M; Holmes, W A; Hornstrup, A; Hovest, W; Huffenberger, K M; Jaffe, T R; Jaffe, A H; Jewell, J; Jones, W C; Juvela, M; Kangaslahti, P; Keihänen, E; Keskitalo, R; Kisner, T S; Knoche, J; Knox, L; Kunz, M; Kurki-Suonio, H; Lagache, G; Lähteenmäki, A; Lamarre, J -M; Lasenby, A; Laureijs, R J; Lawrence, C R; Leach, S; Leahy, J P; Leonardi, R; Lesgourgues, J; Liguori, M; Lilje, P B; Linden-Vørnle, M; López-Caniego, M; Lubin, P M; Macías-Pérez, J F; Maino, D; Mandolesi, N; Maris, M; Marshall, D J; Martin, P G; Martínez-González, E; Masi, S; Matarrese, S; Matthai, F; Mazzotta, P; Meinhold, P R; Melchiorri, A; Mendes, L; Mennella, A; Migliaccio, M; Mitra, S; Moneti, A; Montier, L; Morgante, G; Mortlock, D; Moss, A; Munshi, D; Naselsky, P; Natoli, P; Netterfield, C B; Nørgaard-Nielsen, H U; Novikov, D; Novikov, I; O'Dwyer, I J; Osborne, S; Paci, F; Pagano, L; Paladini, R; Paoletti, D; Partridge, B; Pasian, F; Patanchon, G; Pearson, D; Peel, M; Perdereau, O; Perotto, L; Perrotta, F; Pierpaoli, E; Pietrobon, D; Plaszczynski, S; Pointecouteau, E; Polenta, G; Ponthieu, N; Popa, L; Poutanen, T; Pratt, G W; Prézeau, G; Prunet, S; Puget, J -L; Rachen, J P; Rebolo, R; Reinecke, M; Remazeilles, M; Ricciardi, S; Riller, T; Rocha, G; Rosset, C; Rossetti, M; Roudier, G; Rubiño-Martín, J A; Rusholme, B; Sandri, M; Santos, D; Scott, D; Seiffert, M D; Shellard, E P S; Spencer, L D; Starck, J -L; Stolyarov, V; Stompor, R; Sureau, F; Sutton, D; Suur-Uski, A -S; Sygnet, J -F; Tauber, J A; Tavagnacco, D; Terenzi, L; Toffolatti, L; Tomasi, M; Tristram, M; Tucci, M; Tuovinen, J; Türler, M; Umana, G; Valenziano, L; Valiviita, J; Van Tent, B; Varis, J; Vielva, P; Villa, F; Vittorio, N; Wade, L A; Wandelt, B D; Watson, R; Wilkinson, A; Yvon, D; Zacchei, A; Zonca, A

2014-01-01

We discuss the methods employed to photometrically calibrate the data acquired by the Low Frequency Instrument on Planck. Our calibration is based on a combination of the Orbital Dipole plus the Solar Dipole, caused respectively by the motion of the Planck spacecraft with respect to the Sun and by motion of the Solar System with respect to the CMB rest frame. The latter provides a signal of a few mK with the same spectrum as the CMB anisotropies and is visible throughout the mission. In this data release we rely on the characterization of the Solar Dipole as measured by WMAP. We also present preliminary results (at 44GHz only) on the study of the Orbital Dipole, which agree with the WMAP value of the Solar System speed within our uncertainties. We compute the calibration constant for each radiometer roughly once per hour, in order to keep track of changes in the detectors' gain. Since non-idealities in the optical response of the beams proved to be important, we implemented a fast convolution algorithm which ...

TCP, quantum gravity, the cosmological constant and all that .

International Nuclear Information System (INIS)

Banks, T.

1985-01-01

We study cosmology from the point of view of quantum gravity. Some light is thrown on the nature of time, and it is suggested that the cosmological arrow of time is generated by a spontaneous breakdown of TCP. Conventional cosmological models in which quantum fields interact with a time-dependent gravitational field are shown to describe an approximation to the quantum gravitational wave function which is valid in the long-wavelength limit. Two problems with initial conditions are resolved in models in which a negative bare cosmological constant is cancelled by the classical excitation of a Bose field eta with a very flat potential. These models can also give a natural explanation for the observed value of the cosmological constant. (orig.)

A Fundamental Parameter-Based Calibration Model for an Intrinsic Germanium X-Ray Fluorescence Spectrometer

DEFF Research Database (Denmark)

Christensen, Leif Højslet; Pind, Niels

1982-01-01

A matrix-independent fundamental parameter-based calibration model for an energy-dispersive X-ray fluorescence spectrometer has been developed. This model, which is part of a fundamental parameter approach quantification method, accounts for both the excitation and detection probability. For each...... secondary target a number of relative calibration constants are calculated on the basis of knowledge of the irradiation geometry, the detector specifications, and tabulated fundamental physical parameters. The absolute calibration of the spectrometer is performed by measuring one pure element standard per...

In-Flight Spectral Calibration of the APEX Imaging Spectrometer Using Fraunhofer Lines

Science.gov (United States)

Kuhlmann, Gerrit; Hueni, Andreas; Damm, Aalexander; Brunner, Dominik

2015-11-01

The Airborne Prism EXperiment (APEX) is an imaging spectrometer which allows to observe atmospheric trace gases such as nitrogen dioxide (NO2). Using a high resolution spectrum of solar Fraunhofer lines, APEX measurements collected during flight have been spectrally calibrated for centre wavelength positions (CW) and instrument slit function (ISF) and compared to the laboratory calibration. We find that CWs depend strongly on both across- and along-track position due to spectral smile and CWs dependency on ambient pressure. The width of the ISF is larger than estimated from the laboratory calibration but can be described by a linear scaling of the laboratory values. The ISF width depends on across- but not on along-track direction. The results demonstrate the importance of characterizing and monitoring the instrument performance during flight and will be used to improve the Empa APEX NO2 retrieval algorithm.

ATLAS Tile Calorimeter calibration and monitoring systems

Science.gov (United States)

Cortés-González, Arely

2018-01-01

The ATLAS Tile Calorimeter is the central section of the hadronic calorimeter of the ATLAS experiment and provides important information for reconstruction of hadrons, jets, hadronic decays of tau leptons and missing transverse energy. This sampling calorimeter uses steel plates as absorber and scintillating tiles as active medium. The light produced by the passage of charged particles is transmitted by wavelength shifting fibres to photomultiplier tubes, located in the outer part of the calorimeter. Neutral particles may also produce a signal after interacting with the material and producing charged particles. The readout is segmented into about 5000 cells, each of them being read out by two photomultipliers in parallel. To calibrate and monitor the stability and performance of each part of the readout chain during the data taking, a set of calibration systems is used. This comprises Cesium radioactive sources, Laser, charge injection elements and an integrator based readout system. Information from all systems allows to monitor and equalise the calorimeter response at each stage of the signal production, from scintillation light to digitisation. Calibration runs are monitored from a data quality perspective and used as a cross-check for physics runs. The data quality efficiency achieved during 2016 was 98.9%. These calibration and stability of the calorimeter reported here show that the TileCal performance is within the design requirements and has given essential contribution to reconstructed objects and physics results.

The design and development of CO2 medium-level laser power calibration system for industrial and medical applications in Thailand

Science.gov (United States)

Nontapot, Kanokwan

2018-03-01

The carbon dioxide laser (CO2 laser) is one of the most useful and is the highest CW laser at the present. The laser produces infrared light at 10.6 um. Due to its high power, CO2 lasers are usually used in industrial applications such as cutting and welding, or for engraving at less power. CO2 lasers are also used widely in medical applications, such as laser surgery, skin resurfacing, and removing mold, due to water (biological tissue) absorb light at this wavelength very well. CO2 lasers are also used as LIDAR laser source for military range finding applications because of the transparency of the atmosphere to infrared light. Due to the increasing use of CO2 lasers laser in industrial and medical applications in Thailand, the National Institute of Metrology (Thailand) has set up a CO2 laser power calibration system and provide calibration service to customers this year. The service support calibration of medium-level laser power at wavelength of 10.6 um and at power range 100 mW-10W. The design and development of the calibration system will be presented.

Stability of short-axial-wavelength internal kink modes of an anisotropic plasma

Energy Technology Data Exchange (ETDEWEB)

Faghihi, M.; Schefffel, J.

1987-12-01

The double adiabatic equations are used to study the stability of a cylindrical Z-pinch with respect to small axial wavelength, internal kink (m greater than or equal to 1) modes. It is found that marginally (ideally) unstable, isotropic equilibria are stabilized. Also, constant-current-density equilibria can be stabilized for Psub(perpendicular) > Psub(parallel) and large ..beta..sub(perpendicular).

Calibration of the SphinX experiment at the XACT facility in Palermo

Science.gov (United States)

Collura, A.; Barbera, M.; Varisco, S.; Calderone, G.; Reale, F.; Gburek, S.; Kowalinski, M.; Sylwester, J.; Siarkowski, M.; Bakala, J.; Podgorski, P.; Trzebinski, W.; Plocieniak, S.; Kordylewski, Z.

2008-07-01

Three of the four detectors of the SphinX experiment to be flown on the Russian mission Coronas-Photon have been measured at the XACT Facility of the Palermo Observatory at several wavelengths in the soft X-ray band. We describe the instrumental set-up and report some measurements. The analysis work to obtain the final calibration is still in progress.

Distance measurement using frequency-modulated continuous-wave ladar with calibration by a femtosecond frequency comb

Science.gov (United States)

Liu, Yang; Yang, Linghui; Lin, Jiarui; Zhu, Jigui

2018-01-01

Precise distance measurement is of interest for large-scale manufacturing, future space satellite missions, and other industrial applications. The ranging system with femtosecond optical frequency comb (FOFC) could offer high accuracy, stability and direct traceability to SI definition of the meter. Here, we propose a scheme for length measurement based on the frequency-modulated continuous-wave (FMCW) ladar with a FOFC. In this scheme, the reference interferometer in the FMCW ladar is calibrated by the intensity detection using the FOFC in the time domain within an optical wavelength resolution. With analysis of the theoretical model, this system has the potential to a high-speed, high-accuracy absolute distance measurement. Then, based on the experimental results, the evaluation of the performance of the calibration of the reference arm is discussed. In addition, the performance of this system is evaluated by a single position measurement with different tuning velocities of wavelength. The experimental results show that the reproducibility of the distance measurement is 10-5 level.

Calibration of X-ray densitometers for the determination of uranium and plutonium concentrations in reprocessing input and product solutions

International Nuclear Information System (INIS)

Ottmar, H.; Eberle, H.; Michel-Piper, I.; Kuhn, E.; Johnson, E.

1985-11-01

In June 1985 a calibration exercise has been carried out, which included the calibration of the KfK K-Edge Densitometer for uranium assay in the uranium product solutions from reprocessing, and the calibration of the Hybrid K-Edge/K-XRF Instrument for the determination of total uranium and plutonium in reprocessing input solutions. The calibration measuremnts performed with the two X-ray densitometers are described and analyzed, and calibration constants are evaluated from the obtained results. (orig.)

Long-term calibration monitoring of Spectralon diffusers BRDF in the air-ultraviolet.

Science.gov (United States)

Georgiev, Georgi T; Butler, James J

2007-11-10

Long-term calibration monitoring of the bidirectional reflectance distribution function (BRDF) of Spectralon diffusers in the air-ultraviolet is presented. Four Spectralon diffusers were monitored in this study. Three of the diffusers, designated as H1, H2, and H3, were used in the prelaunch radiance calibration of the Solar Backscatter Ultraviolet/2 (SBUV/2) satellite instruments on National Oceanic and Atmospheric Administration (NOAA) 14 and 16. A fourth diffuser, designated as the 400 diffuser, was used in the prelaunch calibration of the Ozone Mapping and Profiler Suite (OMPS) instrument scheduled for initial flight in 2009 on the National Polar Orbiting Environmental Satellite System Preparatory Project. The BRDF data of this study were obtained between 1994 and 2005 using the scatterometer located in the National Aeronautics and Space Administration Goddard Space Flight Center Diffuser Calibration Laboratory. The diffusers were measured at 13 wavelengths between 230 and 425 nm at the incident and scatter angles used in the prelaunch calibrations of SBUV/2 and OMPS. Spectral features in the BRDF of Spectralon are also discussed. The comparison shows how the air-ultraviolet BRDF of these Spectralon samples changed over time under clean room deployment conditions.

Calibration of new I and C at VR-1 training reactor

International Nuclear Information System (INIS)

Kropik, Martin; Jurickova, Monika

2011-01-01

The paper describes a calibration of the new instrumentation and control (I and C) at the VR-1 training reactor in Prague. The I and C uses uncompensated fission chambers for the power measurement that operate in a pulse or a DC current and a Campbell regime, according to the reactor power. The pulse regime uses discrimination for the avoidance of gamma and noise influence of the measurement. The DC current regime employs a logarithmic amplifier to cover the whole reactor DC current power range with only one electronic circuit. The system computer calculates the real power from the logarithmic data. The Campbell regime is based on evaluation of the root mean square (RMS) value of the neutron noise. The calculated power from Campbell range is based on the square value of the RMS neutron noise data. All data for the power calculation are stored in computer flash memories. To set proper data there, it was necessary to carry out the calibration of the I and C. At first, the proper discrimination value was found while examining the spectrum of the neutron signal from the chamber. The constants for the DC current and Campbell calculations were determined from an independent reactor power measurement. The independent power measuring system that was used for the calibration was accomplished by a compensated current chamber with an electrometer. The calculated calibration constants were stored in the computer flash memories, and the calibrated system was again successfully compared with the independent power measuring system. Finally, proper gamma discrimination of the Campbell system was carefully checked.

Wavelength selection for portable noninvasive blood component measurement system based on spectral difference coefficient and dynamic spectrum

Science.gov (United States)

Feng, Ximeng; Li, Gang; Yu, Haixia; Wang, Shaohui; Yi, Xiaoqing; Lin, Ling

2018-03-01

Noninvasive blood component analysis by spectroscopy has been a hotspot in biomedical engineering in recent years. Dynamic spectrum provides an excellent idea for noninvasive blood component measurement, but studies have been limited to the application of broadband light sources and high-resolution spectroscopy instruments. In order to remove redundant information, a more effective wavelength selection method has been presented in this paper. In contrast to many common wavelength selection methods, this method is based on sensing mechanism which has a clear mechanism and can effectively avoid the noise from acquisition system. The spectral difference coefficient was theoretically proved to have a guiding significance for wavelength selection. After theoretical analysis, the multi-band spectral difference coefficient-wavelength selection method combining with the dynamic spectrum was proposed. An experimental analysis based on clinical trial data from 200 volunteers has been conducted to illustrate the effectiveness of this method. The extreme learning machine was used to develop the calibration models between the dynamic spectrum data and hemoglobin concentration. The experiment result shows that the prediction precision of hemoglobin concentration using multi-band spectral difference coefficient-wavelength selection method is higher compared with other methods.

Genetic multivariate calibration for near infrared spectroscopic determination of protein, moisture, dry mass, hardness and other residues of wheat

OpenAIRE

Özdemir, Durmuş

2006-01-01

Determination of wheat flour quality parameters, such as protein, moisture, dry mass by wet chemistry analyses takes long time. Near infrared spectroscopy (NIR) coupled with multivariate calibration offers a fast and nondestructive alternative to obtain reliable results. However, due to the complexity of the spectra obtained from NIR, some wavelength selection is generally required to improve the predictive ability of multivariate calibration methods. In this study, two different wheat data s...

Tailoring Chirped Moiré Fiber Bragg Gratings for Wavelength-Division-Multiplexing and Optical Code-Division Multiple-Access Applications

Science.gov (United States)

Chen, Lawrence R.; Smith, Peter W. E.

The design and fabrication of chirped Moiré fiber Bragg gratings (CMGs) are presented, which can be used in either (1) transmission as passband filters for providing wavelength selectivity in wavelength-division-multiplexed (WDM) systems or (2) reflection as encoding/decoding elements to decompose short broadband pulses in both wavelength and time in order to implement an optical code-division multiple-access (OCDMA) system. In transmission, the fabricated CMGs have single or multiple flattened passbands ( 12 dB isolation and near constant in-band group delay. It is shown that these filters do not produce any measurable dispersion-induced power penalties when used to provide wavelength selectivity in 2.5 Gbit/s systems. It is also demonstrated how CMGs can be used in reflection to encode/decode short pulses from a wavelength-tunable mode-locked Er-doped fiber laser.

Lateral force calibration in atomic force microscopy: A new lateral force calibration method and general guidelines for optimization

International Nuclear Information System (INIS)

Cannara, Rachel J.; Eglin, Michael; Carpick, Robert W.

2006-01-01

Proper force calibration is a critical step in atomic and lateral force microscopies (AFM/LFM). The recently published torsional Sader method [C. P. Green et al., Rev. Sci. Instrum. 75, 1988 (2004)] facilitates the calculation of torsional spring constants of rectangular AFM cantilevers by eliminating the need to obtain information or make assumptions regarding the cantilever's material properties and thickness, both of which are difficult to measure. Complete force calibration of the lateral signal in LFM requires measurement of the lateral signal deflection sensitivity as well. In this article, we introduce a complete lateral force calibration procedure that employs the torsional Sader method and does not require making contact between the tip and any sample. In this method, a colloidal sphere is attached to a 'test' cantilever of the same width, but different length and material as the 'target' cantilever of interest. The lateral signal sensitivity is calibrated by loading the colloidal sphere laterally against a vertical sidewall. The signal sensitivity for the target cantilever is then corrected for the tip length, total signal strength, and in-plane bending of the cantilevers. We discuss the advantages and disadvantages of this approach in comparison with the other established lateral force calibration techniques, and make a direct comparison with the 'wedge' calibration method. The methods agree to within 5%. The propagation of errors is explicitly considered for both methods and the sources of disagreement discussed. Finally, we show that the lateral signal sensitivity is substantially reduced when the laser spot is not centered on the detector

High-accuracy self-calibration method for dual-axis rotation-modulating RLG-INS

Science.gov (United States)

Wei, Guo; Gao, Chunfeng; Wang, Qi; Wang, Qun; Long, Xingwu

2017-05-01

Inertial navigation system has been the core component of both military and civil navigation systems. Dual-axis rotation modulation can completely eliminate the inertial elements constant errors of the three axes to improve the system accuracy. But the error caused by the misalignment angles and the scale factor error cannot be eliminated through dual-axis rotation modulation. And discrete calibration method cannot fulfill requirements of high-accurate calibration of the mechanically dithered ring laser gyroscope navigation system with shock absorbers. This paper has analyzed the effect of calibration error during one modulated period and presented a new systematic self-calibration method for dual-axis rotation-modulating RLG-INS. Procedure for self-calibration of dual-axis rotation-modulating RLG-INS has been designed. The results of self-calibration simulation experiment proved that: this scheme can estimate all the errors in the calibration error model, the calibration precision of the inertial sensors scale factor error is less than 1ppm and the misalignment is less than 5″. These results have validated the systematic self-calibration method and proved its importance for accuracy improvement of dual -axis rotation inertial navigation system with mechanically dithered ring laser gyroscope.

Evolution of the solar 'constant'

Energy Technology Data Exchange (ETDEWEB)

Newman, M J

1980-06-01

Variations in solar luminosity over geological time are discussed in light of the effect of the solar constant on the evolution of life on earth. Consideration is given to long-term (5 - 7% in a billion years) increases in luminosity due to the conversion of hydrogen into helium in the solar interior, temporary enhancements to solar luminosity due to the accretion of matter from the interstellar medium at intervals on the order of 100 million years, and small-amplitude rapid fluctuations of luminosity due to the stochastic nature of convection on the solar surface. It is noted that encounters with dense interstellar clouds could have had serious consequences for life on earth due to the peaking of the accretion-induced luminosity variation at short wavelengths.

Model calibration and validation for OFMSW and sewage sludge co-digestion reactors

International Nuclear Information System (INIS)

Esposito, G.; Frunzo, L.; Panico, A.; Pirozzi, F.

2011-01-01

Highlights: → Disintegration is the limiting step of the anaerobic co-digestion process. → Disintegration kinetic constant does not depend on the waste particle size. → Disintegration kinetic constant depends only on the waste nature and composition. → The model calibration can be performed on organic waste of any particle size. - Abstract: A mathematical model has recently been proposed by the authors to simulate the biochemical processes that prevail in a co-digestion reactor fed with sewage sludge and the organic fraction of municipal solid waste. This model is based on the Anaerobic Digestion Model no. 1 of the International Water Association, which has been extended to include the co-digestion processes, using surface-based kinetics to model the organic waste disintegration and conversion to carbohydrates, proteins and lipids. When organic waste solids are present in the reactor influent, the disintegration process is the rate-limiting step of the overall co-digestion process. The main advantage of the proposed modeling approach is that the kinetic constant of such a process does not depend on the waste particle size distribution (PSD) and rather depends only on the nature and composition of the waste particles. The model calibration aimed to assess the kinetic constant of the disintegration process can therefore be conducted using organic waste samples of any PSD, and the resulting value will be suitable for all the organic wastes of the same nature as the investigated samples, independently of their PSD. This assumption was proven in this study by biomethane potential experiments that were conducted on organic waste samples with different particle sizes. The results of these experiments were used to calibrate and validate the mathematical model, resulting in a good agreement between the simulated and observed data for any investigated particle size of the solid waste. This study confirms the strength of the proposed model and calibration procedure

Local instabilities in magnetized rotational flows: A short-wavelength approach

OpenAIRE

Kirillov, Oleg N.; Stefani, Frank; Fukumoto, Yasuhide

2014-01-01

We perform a local stability analysis of rotational flows in the presence of a constant vertical magnetic field and an azimuthal magnetic field with a general radial dependence. Employing the short-wavelength approximation we develop a unified framework for the investigation of the standard, the helical, and the azimuthal version of the magnetorotational instability, as well as of current-driven kink-type instabilities. Considering the viscous and resistive setup, our main focus is on the cas...

The role of the second zero-dispersion wavelength in generation of supercontinua and brigth-bright soliton-pairs across the zero-dispersion wavelength

DEFF Research Database (Denmark)

Frosz, Michael Henoch; Falk, Peter Andreas; Bang, Ole

2005-01-01

Supercontinuum generation with femtosecond pulses in photonic crystal fibers with two zero-dispersion wavelengths (ZDWs) is investigated numerically. The role of the higher ZDW is examined for 5 fiber designs with a nearly constant lower ZDW. It is found that the resulting spectrum is mainly....... Further, the generation of a bright-bright soliton-pair from an initial single red-shifted soliton is found. The soliton-pair has one color in the anomalous dispersion region and the other color in the normal dispersion region, which has not previously been described for bright-bright soliton-pairs....

Multi-Wavelength Variability in PKS 2155-304 Y. G. Zheng1,2, L ...

Indian Academy of Sciences (India)

2009), we attempt to model the multi-wavelength variability in PKS 2155-304. We assume that the acceleration process is a stochastic process and we describe it as the diffusion of the particle momentum. Throughout the paper, we assume the. Hubble constant H0 = 70 km s−1. Mpc. −1. , the matter energy density M = 0.27,.

Multi-Wavelength Studies on H2O Maser Host Galaxies J. S. Zhang ...

Indian Academy of Sciences (India)

on two projects: X-ray data analysis of individual maser source using. X-ray penetrability to explore maser host obscured AGN; multi- wavelength ... Figure 1. Adaptively smoothed three-color image in 0.3–8.0keV and spectra with fitting ... It provides a perspective to improve the accuracy of the Hubble constant H0 and to.

Calibration of IR test chambers with the missile defense transfer radiometer

Science.gov (United States)

Kaplan, Simon G.; Woods, Solomon I.; Carter, Adriaan C.; Jung, Timothy M.

2013-05-01

The Missile Defense Transfer Radiometer (MDXR) is designed to calibrate infrared collimated and flood sources over the fW/cm2 to W/cm2 power range from 3 μm to 28μ m in wavelength. The MDXR operates in three different modes: as a filter radiometer, a Fourier-transform spectrometer (FTS)-based spectroradiometer, and as an absolute cryogenic radiometer (ACR). Since 2010, the MDXR has made measurements of the collimated infrared irradiance at the output port of seven different infrared test chambers at several facilities. We present a selection of results from these calibration efforts compared to signal predictions from the respective chamber models for the three different MDXR calibration modes. We also compare the results to previous measurements made of the same chambers with a legacy transfer radiometer, the NIST BXR. In general, the results are found to agree within their combined uncertainties, with the MDXR having 30 % lower uncertainty and greater spectral coverage.

The Laser calibration of the ATLAS Tile Calorimeter during the LHC run 1

CERN Document Server

INSPIRE-00305555

2016-10-12

This article describes the Laser calibration system of the Atlas hadronic Tile Calorimeter that has been used during the run 1 of the LHC. First, the stability of the system associated readout electronics is studied. It is found to be stable with variations smaller than 0.6 %. Then, the method developed to compute the calibration constants, to correct for the variations of the gain of the calorimeter photomultipliers, is described. These constants were determined with a statistical uncertainty of 0.3 % and a systematic uncertainty of 0.2 % for the central part of the calorimeter and 0.5 % for the end-caps. Finally, the detection and correction of timing mis-configuration of the Tile Calorimeter using the Laser system are also presented.

Underdense radiation sources: Moving towards longer wavelengths

Energy Technology Data Exchange (ETDEWEB)

Back, C.A.; Kilkenny, J.D. [General Atomics, San Diego, California (United States); Seely, J.F.; Weaver, J.L. [Naval Research Laboratory, Washington, DC (United States); Feldman, U. [Artep Inc., Ellicott City, MD (United States); Tommasini, R.; Glendinning, S.G.; Chung, H.K.; Rosen, M.; Lee, R.W.; Scott, H.A. [Lawrence Livermore National Laboratory, California (United States); Tillack, M. [U. C. San Diego, La Jolla, CA (United States)

2006-06-15

Underdense radiation sources have been developed to provide efficient laboratory multi-keV radiation sources for radiography and radiation hardening studies. In these plasmas laser absorption by inverse Bremsstrahlung leads to high x-ray conversion efficiency because of efficient ionization of the low density aerogel or gas targets. Now we performing experiments in the soft x-ray energy regime where the atomic physics models are much more complicated. In recent experiments at the NIKE laser, we have irradiated a Ti-doped SiO{sub 2} aerogel with up to 1650 J of 248 nm wavelength light. The absolute Ti L-shell emission in the 200-800 eV range is measured with a diagnostic that uses a transmission grating coupled to Si photodiodes. We will give an overview of the temporally-resolved absolutely calibrated spectra obtained over a range of conditions. (authors)

Underdense radiation sources: Moving towards longer wavelengths

International Nuclear Information System (INIS)

Back, C.A.; Kilkenny, J.D.; Seely, J.F.; Weaver, J.L.; Feldman, U.; Tommasini, R.; Glendinning, S.G.; Chung, H.K.; Rosen, M.; Lee, R.W.; Scott, H.A.; Tillack, M.

2006-01-01

Underdense radiation sources have been developed to provide efficient laboratory multi-keV radiation sources for radiography and radiation hardening studies. In these plasmas laser absorption by inverse Bremsstrahlung leads to high x-ray conversion efficiency because of efficient ionization of the low density aerogel or gas targets. Now we performing experiments in the soft x-ray energy regime where the atomic physics models are much more complicated. In recent experiments at the NIKE laser, we have irradiated a Ti-doped SiO 2 aerogel with up to 1650 J of 248 nm wavelength light. The absolute Ti L-shell emission in the 200-800 eV range is measured with a diagnostic that uses a transmission grating coupled to Si photodiodes. We will give an overview of the temporally-resolved absolutely calibrated spectra obtained over a range of conditions. (authors)

Optical fiber-based full Mueller polarimeter for endoscopic imaging using a two-wavelength simultaneous measurement method.

Science.gov (United States)

Vizet, Jérémy; Manhas, Sandeep; Tran, Jacqueline; Validire, Pierre; Benali, Abdelali; Garcia-Caurel, Enric; Pierangelo, Angelo; De Martino, Antonello; Pagnoux, Dominique

2016-07-01

This paper reports a technique based on spectrally differential measurement for determining the full Mueller matrix of a biological sample through an optical fiber. In this technique, two close wavelengths were used simultaneously, one for characterizing the fiber and the other for characterizing the assembly of fiber and sample. The characteristics of the fiber measured at one wavelength were used to decouple its contribution from the measurement on the assembly of fiber and sample and then to extract sample Mueller matrix at the second wavelength. The proof of concept was experimentally validated by measuring polarimetric parameters of various calibrated optical components through the optical fiber. Then, polarimetric images of histological cuts of human colon tissues were measured, and retardance, diattenuation, and orientation of the main axes of fibrillar regions were displayed. Finally, these images were successfully compared with images obtained by a free space Mueller microscope. As the reported method does not use any moving component, it offers attractive integration possibilities with an endoscopic probe.

Novel Real-time Alignment and Calibration of the LHCb detector in Run2

Science.gov (United States)

Martinelli, Maurizio; LHCb Collaboration

2017-10-01

LHCb has introduced a novel real-time detector alignment and calibration strategy for LHC Run2. Data collected at the start of the fill are processed in a few minutes and used to update the alignment parameters, while the calibration constants are evaluated for each run. This procedure improves the quality of the online reconstruction. For example, the vertex locator is retracted and reinserted for stable beam conditions in each fill to be centred on the primary vertex position in the transverse plane. Consequently its position changes on a fill-by-fill basis. Critically, this new real-time alignment and calibration procedure allows identical constants to be used in the online and offline reconstruction, thus improving the correlation between triggered and offline-selected events. This offers the opportunity to optimise the event selection in the trigger by applying stronger constraints. The required computing time constraints are met thanks to a new dedicated framework using the multi-core farm infrastructure for the trigger. The motivation for a real-time alignment and calibration of the LHCb detector is discussed from both the operational and physics performance points of view. Specific challenges of this novel configuration are discussed, as well as the working procedures of the framework and its performance.

Calibration, monitoring, and control of complex detector systems

International Nuclear Information System (INIS)

Breidenbach, M.

1981-01-01

LEP detectors will probably be complex devices having tens of subsystems; some subsystems having perhaps tens of thousands of channels. Reasonable design goals for such a detector will include economic use of money and people, rapid and reliable calibration and monitoring of the detector, and simple control and operation of the device. The synchronous operation of an e + e - storage ring, coupled with its relatively low interaction rate, allow the design of simple circuits for time and charge measurements. These circuits, and more importantly, the basic detector channels, can usually be tested and calibrated by signal injection into the detector. Present detectors utilize semi-autonomous controllers which collect such calibration data and calculate statistics as well as control sparse data scans. Straightforward improvements in programming technology should move the entire calibration into these local controllers, so that calibration and testing time will be a constant independent of the number of channels in a system. Considerable programming effort may be saved by emphasizing the similarities of the subsystems, so that the subsystems can be described by a reasonable database and general purpose calibration and test routines can be used. Monitoring of the apparatus will probably continue to be of two classes: 'passive' histogramming of channel occupancies and other more complex combinations of the data; and 'active' injection of test patterns and calibration signals during a run. The relative importance of active monitoring will increase for the low data rates expected off resonances at high s. Experience at SPEAR and PEP is used to illustrate these approaches. (Auth.)

Calibration, Monitoring, and Control of Complex Detector Systems

Science.gov (United States)

Breidenbach, M.

1981-04-01

LEP Detectors will probably be complex devices having tens of subsystems; some subsystems having perhaps tens of thousands of channels. Reasonable design goals for such a detector will include economic use of money and people, rapid and reliable calibration and monitoring of the detector, and simple control and operation of the device. The synchronous operation of an e+e- storage ring, coupled with its relatively low interaction rate, allow the design of simple circuits for time and charge measurements. These circuits, and more importantly, the basic detector channels, can usually be tested and calibrated by signal injection into the detector. Present detectors utilize semi-autonomous controllers which collect such calibration data and calculate statistics as well as control sparse data scans. Straightforward improvements in programming technology should move the entire calibration into these local controllers, so that calibration and testing time will be a constant independent of the number of channels in a system. Considerable programming effort may be saved by emphasizing the similarities of the subsystems, so that the subsystems can be described by a reasonable database and general purpose calibration and test routines can be used. Monitoring of the apparatus will probably continue to be of two classes: "passive" histogramming of channel occupancies and other more complex combinations of the data; and "active" injection of test patterns and calibration signals during a run. The relative importance of active monitoring will increase for the low data rates expected off resonances at high s. Experience at SPEAR and PEP is used to illustrate these approaches.

A COMPARISON OF LIDAR REFLECTANCE AND RADIOMETRICALLY CALIBRATED HYPERSPECTRAL IMAGERY

Directory of Open Access Journals (Sweden)

A. Roncat

2016-06-01

Full Text Available In order to retrieve results comparable under different flight parameters and among different flight campaigns, passive remote sensing data such as hyperspectral imagery need to undergo a radiometric calibration. While this calibration, aiming at the derivation of physically meaningful surface attributes such as a reflectance value, is quite cumbersome for passively sensed data and relies on a number of external parameters, the situation is by far less complicated for active remote sensing techniques such as lidar. This fact motivates the investigation of the suitability of full-waveform lidar as a “single-wavelength reflectometer” to support radiometric calibration of hyperspectral imagery. In this paper, this suitability was investigated by means of an airborne hyperspectral imagery campaign and an airborne lidar campaign recorded over the same area. Criteria are given to assess diffuse reflectance behaviour; the distribution of reflectance derived by the two techniques were found comparable in four test areas where these criteria were met. This is a promising result especially in the context of current developments of multi-spectral lidar systems.

Wavelength dependence for the photoreactions of DNA-Psoralen monoadducts. 1. Photoreversal of monoadducts

International Nuclear Information System (INIS)

Shi, Y.; Hearst, J.E.

1987-01-01

The authors have studied the wavelength dependence for the photoreversal of a monoadducted psoralen derivative, HMT [4'(hydroxymethyl)-4,5',8-trimethylpsoralen], in a single-stranded deoxyoligonucleotide (5'-GAAGCTACGAGC-3'). The psoralen was covalently attached to the thymidine residue in the oligonucleotide as either a furan-side monoadduct, which is formed through the cycloaddition between the 4',5' double bond of the psoralen and the 5,6 double bond of the thymidine, or a pyrone-side monoadduct, which is formed through the cycloaddition between the 3,4 double bond of the psoralen and the 5,6 double bond of the thymidine. As a comparison, they have also investigated the wavelength-dependent photoreversal of the isolated thymidine-HMT monoadducts. All photoreversal action spectra correlate with the extinction spectra of the isolate monoadducts. In the case of the pyrone-side monoadduct, two absorption bands contribute to the photoreversal with a quantum yield of 2 x 10 -2 at wavelengths below 250 nm and 7 x 10 -3 at wavelengths from 287 to 314 nm. The incorporation of the monoadduct into the DNA oligomer had little effect upon the photoreversal rate. For the furan-side monoadduct at least three absorption bands contribute to the photoreversal. The quantum yield varied from 5 x 10 -2 at wavelengths below 250 nm to 7 x 10 -4 at wavelengths between 295 and 365 nm. In contrast to the case of the pyrone-side monoadduct, the incorporation of the furan-side monoadduct into the DNA oligomer reduced the photoreversal rate constant at wavelengths above 285 nm

A low-temperature (4-300K) constant volume gas thermometer

International Nuclear Information System (INIS)

Combarieu, A. de

1976-01-01

A constant volume gas thermometer was built to calibrate the various secondary thermometers used at low temperature. This gas thermometer is placed in a cryostat where any stable temperature between 4 and 300K may be obtained. The principle is outlined, then the gas thermometer and its auxiliary equipment are briefly described; the corrections to be applied to the results are given and a table shows the values obtained [fr

Laboratory-Based BRDF Calibration of Radiometric Tarps

Science.gov (United States)

Georgiev, Georgi T.; Butler, James J.

2007-01-01

The current study provides the remote sensing community with important high accuracy laboratory-based BRDF calibration of radiometric tarps. The results illustrate the dependence of tarps' weft and warp threads orientation on BRDF. The study was done at incident angles of 0deg, 10deg, and 30deg; scatter zenith angles from 0deg to 60deg, and scatter azimuth angles of 0deg, 45deg, 90deg, 135deg, and 180deg. The wavelengths were 485nm, 550nm, 633nm and 800nm. The dependence is well defined at all measurement geometries and wavelengths. It can be as high as 8% at 0deg incident angle and 2% at 30deg incident angle. The fitted BRDF data show a very small discrepancy from the measured ones. New data on the forward and backscatter properties of radiometric tarps is reported. The backward scatter is well pronounced for the white samples. The black sample has well pronounced forward scatter. The BRDF characterization of radiometric tarps can be successfully extended to other structured surface fabric samples. The results are NIST traceable.

Local Analysis Approach for Short Wavelength Geopotential Variations

Science.gov (United States)

Bender, P. L.

2009-12-01

results from different arcs crossing the region can be seen most easily for an orbit with moderate inclination, such as 50 to 65 deg., so that the crossing angle between south-to-north (S-N) and N-S passes is fairly large over most regions well away from the poles. In that case, after filtering to pass the shorter wavelengths, the results for a given time interval can be combined to give the short wavelength W-E variations in the geopotential efficiently. For continents with extensive meteorological measurements available, like Europe and North America, a very rough guess at the surface mass density variation uncertainties is about 3 kg/m^2. This is based on the apparent accuracy of carefully calibrated surface pressure measurements. If a substantial part of the resulting uncertainties in the geopotential height at satellite altitude are at wavelengths less than about 1,500 km, they will dominate the measurement uncertainty at short spatial wavelengths for a GRACE-type mission with laser interferometry. This would be the case, even if the uncertainty in the atmospheric and oceanic mass distribution at large distances has a fairly small effect. However, the geopotential accuracy would still be substantially better than for the results achievable with a microwave ranging system.

Filament instability under constant loads

Science.gov (United States)

Monastra, A. G.; Carusela, M. F.; D’Angelo, M. V.; Bruno, L.

2018-04-01

Buckling of semi-flexible filaments appears in different systems and scales. Some examples are: fibers in geophysical applications, microtubules in the cytoplasm of eukaryotic cells and deformation of polymers freely suspended in a flow. In these examples, instabilities arise when a system’s parameter exceeds a critical value, being the Euler force the most known. However, the complete time evolution and wavelength of buckling processes are not fully understood. In this work we solve analytically the time evolution of a filament under a constant compressive force in the small amplitude approximation. This gives an insight into the variable force scenario in terms of normal modes. The evolution is highly sensitive to the initial configuration and to the magnitude of the compressive load. This model can be a suitable approach to many different real situations.

Establishing BRDF calibration capabilities through shortwave infrared

Science.gov (United States)

Georgiev, Georgi T.; Butler, James J.; Thome, Kurt; Cooksey, Catherine; Ding, Leibo

2017-09-01

Satellite instruments operating in the reflective solar wavelength region require accurate and precise determination of the Bidirectional Reflectance Distribution Functions (BRDFs) of the laboratory and flight diffusers used in their pre-flight and on-orbit calibrations. This paper advances that initial work and presents a comparison of spectral Bidirectional Reflectance Distribution Function (BRDF) and Directional Hemispherical Reflectance (DHR) of Spectralon*, a common material for laboratory and onorbit flight diffusers. A new measurement setup for BRDF measurements from 900 nm to 2500 nm located at NASA Goddard Space Flight Center (GSFC) is described. The GSFC setup employs an extended indium gallium arsenide detector, bandpass filters, and a supercontinuum light source. Comparisons of the GSFC BRDF measurements in the shortwave infrared (SWIR) with those made by the National Institute of Standards and Technology (NIST) Spectral Tri-function Automated Reference Reflectometer (STARR) are presented. The Spectralon sample used in this study was 2 inch diameter, 99% white pressed and sintered Polytetrafluoroethylene (PTFE) target. The NASA/NIST BRDF comparison measurements were made at an incident angle of 0° and viewing angle of 45° . Additional BRDF data not compared to NIST were measured at additional incident and viewing angle geometries and are not presented here. The total combined uncertainty for the measurement of BRDF in the SWIR range made by the GSFC scatterometer is less than 1% (k = 1). This study is in support of the calibration of the Radiation Budget Instrument (RBI) and Visible Infrared Imaging Radiometer Suit (VIIRS) instruments of the Joint Polar Satellite System (JPSS) and other current and future NASA remote sensing missions operating across the reflected solar wavelength region.

Wavelength converter placement for different RWA algorithms in wavelength-routed all-optical networks

Science.gov (United States)

Chu, Xiaowen; Li, Bo; Chlamtac, Imrich

2002-07-01

Sparse wavelength conversion and appropriate routing and wavelength assignment (RWA) algorithms are the two key factors in improving the blocking performance in wavelength-routed all-optical networks. It has been shown that the optimal placement of a limited number of wavelength converters in an arbitrary mesh network is an NP complete problem. There have been various heuristic algorithms proposed in the literature, in which most of them assume that a static routing and random wavelength assignment RWA algorithm is employed. However, the existing work shows that fixed-alternate routing and dynamic routing RWA algorithms can achieve much better blocking performance. Our study in this paper further demonstrates that the wavelength converter placement and RWA algorithms are closely related in the sense that a well designed wavelength converter placement mechanism for a particular RWA algorithm might not work well with a different RWA algorithm. Therefore, the wavelength converter placement and the RWA have to be considered jointly. The objective of this paper is to investigate the wavelength converter placement problem under fixed-alternate routing algorithm and least-loaded routing algorithm. Under the fixed-alternate routing algorithm, we propose a heuristic algorithm called Minimum Blocking Probability First (MBPF) algorithm for wavelength converter placement. Under the least-loaded routing algorithm, we propose a heuristic converter placement algorithm called Weighted Maximum Segment Length (WMSL) algorithm. The objective of the converter placement algorithm is to minimize the overall blocking probability. Extensive simulation studies have been carried out over three typical mesh networks, including the 14-node NSFNET, 19-node EON and 38-node CTNET. We observe that the proposed algorithms not only outperform existing wavelength converter placement algorithms by a large margin, but they also can achieve almost the same performance comparing with full wavelength

Improving the Ar I and II branching ratio calibration method: Monte Carlo simulations of effects from photon scattering/reflecting in hollow cathodes

Science.gov (United States)

Lawler, J. E.; Den Hartog, E. A.

2018-03-01

The Ar I and II branching ratio calibration method is discussed with the goal of improving the technique. This method of establishing a relative radiometric calibration is important in ongoing research to improve atomic transition probabilities for quantitative spectroscopy in astrophysics and other fields. Specific suggestions are presented along with Monte Carlo simulations of wavelength dependent effects from scattering/reflecting of photons in a hollow cathode.

Factors that affect the calibration of turbines in single-phase flow

International Nuclear Information System (INIS)

Piper, T.C.

1977-05-01

Basic turbine operation in single-phase flow is related. Causes and relative magnitudes of retarding torque are given for two sizes of turbines when used for water flow measurement. An equation for slip caused by retarding torques is given. Evaluation of turbine slip behavior at the turbine low flow region shows that bearing retarding torques, change in flow patterns, or other effects can predominate in the relatively large changes in the calibration ''constant'' that occurs there. Fluid lubricity is singled out as an important fluid property in certain types of bearings and flow. Temperature induced changes in turbine size are shown to cause calibration changes if a turbine is used at a temperature significantly different than that at which it was calibrated

Factors that affect the calibration of turbines in single-phase flow

Energy Technology Data Exchange (ETDEWEB)

Piper, T. C.

1977-05-01

Basic turbine operation in single-phase flow is related. Causes and relative magnitudes of retarding torque are given for two sizes of turbines when used for water flow measurement. An equation for slip caused by retarding torques is given. Evaluation of turbine slip behavior at the turbine low flow region shows that bearing retarding torques, change in flow patterns, or other effects can predominate in the relatively large changes in the calibration ''constant'' that occurs there. Fluid lubricity is singled out as an important fluid property in certain types of bearings and flow. Temperature induced changes in turbine size are shown to cause calibration changes if a turbine is used at a temperature significantly different than that at which it was calibrated.

Estimation of neutron mean wavelength from rocking curve dataThis work is a contribution of NIST, an agency of the US Government, and not subject to copyright laws.

Science.gov (United States)

Coakley, K. J.; Chowdhuri, Z.; Snow, W. M.; Richardson, J. M.; Dewey, M. S.

2003-01-01

At NIST, an in-beam neutron lifetime experiment is underway. In part of the experiment, a neutron detector is calibrated. The accuracy of the detector calibration depends, in part, on how accurately the mean wavelength of a neutron beam can be estimated from rocking curve data. Based on a stochastic model for neutron scattering, we simulate rocking curve data. To speed up the simulation, an importance sampling method is used. For the cases studied, importance sampling reduces the execution time of the simulation code by over a factor of 500. For simulated data, the statistical bias of the mean wavelength estimate is found to be 0.004%. This work is a contribution of NIST, an agency of the US Government, and not subject to copyright laws.

Calibration and Data Quality systems of the ATLAS Tile Calorimeter during the LHC Run-I operations

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00306374; The ATLAS collaboration

2016-01-01

The Tile Calorimeter is the hadronic calorimeter covering the central region of the ATLAS detector at the LHC. It consists of thin steel plates and scintillating tiles. Wavelength shifting fibres coupled to the tiles collect the produced light and are read out by photomultiplier tubes. The calibration scheme of the Tile Calorimeter comprises Cs radioactive source, laser and charge injection systems. Each stage of the signal production of the calorimeter from scintillation light to digitization is monitored and equalized. Description of the different TileCal calibration systems as well as the results on their performance in terms of calibration factors, linearity and stability are given. The data quality procedures and data quality efficiency of the Tile Calorimeter during the LHC data-taking period are presented as well.

Calibration and Data Quality systems of the ATLAS Tile Calorimeter during the LHC Run-I operations

CERN Document Server

Zenis, Tibor; The ATLAS collaboration

2015-01-01

The Tile Calorimeter is the hadronic calorimeter covering the central region of the ATLAS detector at the LHC. It consists of thin steel plates and scintillating tiles. Wavelength shifting fibres coupled to the tiles collect the produced light and are read out by photomultiplier tubes. The calibration scheme of the Tile Calorimeter comprises Cs radioactive source, laser and charge injection systems. Each stage of the signal production of the calorimeter from scintillation light to digitization is monitored and equalized. Description of the different TileCal calibration systems as well as results on their performance in terms of calibration factors, linearity and stability will be given. The data quality procedures and data quality efficiency of the Tile Calorimeter during the LHC data-taking period are presented as well.

Optical constants and dispersion equations of lecithin, cholesterol, fucose, and chloroform: measurements in vacuum-ultraviolet to visible wavelength regions

International Nuclear Information System (INIS)

Andersen, M.; Nir, S.; Heller, J.M. Jr.; Painter, L.R.

1978-01-01

The optical constants, n and k, of solutions of lecithin, cholesterol, and fucose and of the solvent chloroform were measured for the spectral region 1348 to 6407 A by a reflectance method. Absorption peaks were found in chloroform at about 1393 and 1631 A and were attributed, respectively, to sigma → sigma/sup */ electron transitions at the C--H and C--Cl bonds and an n → sigma/sup */ electron transition at the C--Cl bond. A procedure for the determination of the optical constants of a solute from those of the solution and solvent is developed and applied. The procedure is also applied to calculate the optical constants of a solution from those of the components. From the values of the optical constants, dispersion equation parameters and van der Waals parameters were calculated for the compounds. The static electronic polarizabilities of the substances studies were found to depend little (less than 6%) on the concentration of solution used in the measurement. Values of polarizabilities obtained agreed closely with those obtained by the addition of bond polarizabilities

Long wavelength limit of evolution of nonlinear cosmological perturbations

International Nuclear Information System (INIS)

Hamazaki, Takashi

2008-01-01

In the general matter composition where the multiple scalar fields and the multiple perfect fluids coexist, in the leading order of the gradient expansion, we construct all of the solutions of the nonlinear evolutions of the locally homogeneous universe. From the momentum constraint, we derive the constraints which the solution constants of the locally homogeneous universe must satisfy. We construct the gauge invariant perturbation variables in the arbitrarily higher order nonlinear cosmological perturbation theory around the spatially flat Friedmann-Robertson-Walker universe. We construct the nonlinear long wavelength limit formula representing the long wavelength limit of the evolution of the nonlinear gauge invariant perturbation variables in terms of perturbations of the evolutions of the locally homogeneous universe. By using the long wavelength limit formula, we investigate the evolution of nonlinear cosmological perturbations in the universe dominated by the multiple slow rolling scalar fields with an arbitrary potential. The τ function and the N potential introduced in this paper make it possible to write the evolution of the multiple slow rolling scalar fields with an arbitrary interaction potential and the arbitrarily higher order nonlinear Bardeen parameter at the end of the slow rolling phase analytically. It is shown that the nonlinear parameters such as f NL and g NL are suppressed by the slow rolling expansion parameters.

PLEIADES ABSOLUTE CALIBRATION : INFLIGHT CALIBRATION SITES AND METHODOLOGY

Directory of Open Access Journals (Sweden)

S. Lachérade

2012-07-01

Full Text Available In-flight calibration of space sensors once in orbit is a decisive step to be able to fulfil the mission objectives. This article presents the methods of the in-flight absolute calibration processed during the commissioning phase. Four In-flight calibration methods are used: absolute calibration, cross-calibration with reference sensors such as PARASOL or MERIS, multi-temporal monitoring and inter-bands calibration. These algorithms are based on acquisitions over natural targets such as African deserts, Antarctic sites, La Crau (Automatic calibration station and Oceans (Calibration over molecular scattering or also new extra-terrestrial sites such as the Moon and selected stars. After an overview of the instrument and a description of the calibration sites, it is pointed out how each method is able to address one or several aspects of the calibration. We focus on how these methods complete each other in their operational use, and how they help building a coherent set of information that addresses all aspects of in-orbit calibration. Finally, we present the perspectives that the high level of agility of PLEIADES offers for the improvement of its calibration and a better characterization of the calibration sites.

Multi-wavelength Characterization of Brown and Black Carbon from Filter Samples

Science.gov (United States)

Johnson, M. M.; Yatavelli, R. L. N.; Chen, L. W. A. A.; Gyawali, M. S.; Arnott, W. P.; Wang, X.; Chakrabarty, R. K.; Moosmüller, H.; Watson, J. G.; Chow, J. C.

2014-12-01

Particulate matter (PM) scatters and absorbs solar radiation and thereby affects visibility, the Earth's radiation balance, and properties and lifetimes of clouds. Understanding the radiative forcing (RF) of PM is essential to reducing the uncertainty in total anthropogenic and natural RF. Many instruments that measure light absorption coefficients (βabs [λ], Mm-1) of PM have used light at near-infrared (NIR; e.g., 880 nm) or red (e.g., 633 nm) wavelengths. Measuring βabs over a wider wavelength range, especially including the ultraviolet (UV) and visible, allows for contributions from black carbon (BC), brown carbon (BrC), and mineral dust (MD) to be differentiated. This will help to determine PM RF and its emission sources. In this study, source and ambient samples collected on Teflon-membrane and quartz-fiber filters are used to characterize and develop a multi-wavelength (250 - 1000 nm) filter-based measurement method of PM light absorption. A commercially available UV-visible spectrometer coupled with an integrating sphere is used for quantifying diffuse reflectance and transmittance of filter samples, from which βabs and absorption Ǻngström exponents (AAE) of the PM deposits are determined. The filter-based light absorption measurements of laboratory generated soot and biomass burning aerosol are compared to 3-wavelength photoacoustic absorption measurements to evaluate filter media and loading effects. Calibration factors are developed to account for differences between filter types (Teflon-membrane vs. quartz-fiber), and between filters and in situ photoacoustic absorption values. Application of multi-spectral absorption measurements to existing archived filters, including specific source samples (e.g. diesel and gasoline engines, biomass burning, dust), will also be discussed.

Modeling microelectrode biosensors: free-flow calibration can substantially underestimate tissue concentrations.

Science.gov (United States)

Newton, Adam J H; Wall, Mark J; Richardson, Magnus J E

2017-03-01

Microelectrode amperometric biosensors are widely used to measure concentrations of analytes in solution and tissue including acetylcholine, adenosine, glucose, and glutamate. A great deal of experimental and modeling effort has been directed at quantifying the response of the biosensors themselves; however, the influence that the macroscopic tissue environment has on biosensor response has not been subjected to the same level of scrutiny. Here we identify an important issue in the way microelectrode biosensors are calibrated that is likely to have led to underestimations of analyte tissue concentrations. Concentration in tissue is typically determined by comparing the biosensor signal to that measured in free-flow calibration conditions. In a free-flow environment the concentration of the analyte at the outer surface of the biosensor can be considered constant. However, in tissue the analyte reaches the biosensor surface by diffusion through the extracellular space. Because the enzymes in the biosensor break down the analyte, a density gradient is set up resulting in a significantly lower concentration of analyte near the biosensor surface. This effect is compounded by the diminished volume fraction (porosity) and reduction in the diffusion coefficient due to obstructions (tortuosity) in tissue. We demonstrate this effect through modeling and experimentally verify our predictions in diffusive environments. NEW & NOTEWORTHY Microelectrode biosensors are typically calibrated in a free-flow environment where the concentrations at the biosensor surface are constant. However, when in tissue, the analyte reaches the biosensor via diffusion and so analyte breakdown by the biosensor results in a concentration gradient and consequently a lower concentration around the biosensor. This effect means that naive free-flow calibration will underestimate tissue concentration. We develop mathematical models to better quantify the discrepancy between the calibration and tissue

Surface topography acquisition method for double-sided near-right-angle structured surfaces based on dual-probe wavelength scanning interferometry.

Science.gov (United States)

Zhang, Tao; Gao, Feng; Jiang, Xiangqian

2017-10-02

This paper proposes an approach to measure double-sided near-right-angle structured surfaces based on dual-probe wavelength scanning interferometry (DPWSI). The principle and mathematical model is discussed and the measurement system is calibrated with a combination of standard step-height samples for both probes vertical calibrations and a specially designed calibration artefact for building up the space coordinate relationship of the dual-probe measurement system. The topography of the specially designed artefact is acquired by combining the measurement results with white light scanning interferometer (WLSI) and scanning electron microscope (SEM) for reference. The relative location of the two probes is then determined with 3D registration algorithm. Experimental validation of the approach is provided and the results show that the method is able to measure double-sided near-right-angle structured surfaces with nanometer vertical resolution and micrometer lateral resolution.

Dosimetry and Calibration Section

International Nuclear Information System (INIS)

Otto, T.

1999-01-01

The Dosimetry and Calibration Section fulfils two tasks within CERN's Radiation Protection Group: the Individual Dosimetry Service monitors more than 5000 persons potentially exposed to ionizing radiation on the CERN sites, and the Calibration Laboratory verifies throughout the year, at regular intervals, over 1000 instruments, monitors, and electronic dosimeters used by RP Group. The establishment of a Quality Assurance System for the Individual Dosimetry Service, a requirement of the new Swiss Ordinance for personal dosimetry, put a considerable workload on the section. Together with an external consultant it was decided to identify and then describe the different 'processes' of the routine work performed in the dosimetry service. The resulting Quality Manual was submitted to the Federal Office for Public Health in Bern in autumn. The CERN Individual Dosimetry Service will eventually be officially endorsed after a successful technical test in March 1999. On the technical side, the introduction of an automatic development machine for gamma films was very successful. It processes the dosimetric films without an operator being present, and its built-in regeneration mechanism keeps the concentration of the processing chemicals at a constant level

Calibration of an advanced photon source linac beam position monitor used for positron position measurement of a beam containing both positrons and electrons

International Nuclear Information System (INIS)

Sereno, Nicholas S.

1998-01-01

The Advanced Photon Source (APS) linac beam position monitors can be used to monitor the position of a beam containing both positrons and electrons. To accomplish this task, both the signal at the bunching frequency of 2856 MHz and the signal at 2x2856 MHz are acquired and processed for each stripline. The positron beam position is obtained by forming a linear combination of both 2856 and 5712 MHz signals for each stripline and then performing the standard difference over sum computation. The required linear combination of the 2856 and 5712 MHz signals depends on the electrical calibration of each stripline/cable combination. In this paper, the calibration constants for both 2856 MHz and 5712 MHz signals for each stripline are determined using a pure beam of electrons. The calibration constants are obtained by measuring the 2856 and 5712 MHz stripline signals at various electron beam currents and positions. Finally, the calibration constants measured using electrons are used to determine positron beam position for the mixed beam case

Wavelength-stepped, actively mode-locked fiber laser based on wavelength-division-multiplexed optical delay lines

Science.gov (United States)

Lee, Eunjoo; Kim, Byoung Yoon

2017-12-01

We propose a new scheme for an actively mode-locked wavelength-swept fiber laser that produces a train of discretely wavelength-stepped pulses from a short fiber cavity. Pulses with different wavelengths are split and combined by standard wavelength division multiplexers with fiber delay lines. As a proof of concept, we demonstrate a laser using an erbium doped fiber amplifier and commercially available wavelength-division multiplexers with wavelength spacing of 0.8 nm. The results show simultaneous mode-locking at three different wavelengths. Laser output parameters in time domain, optical and radio frequency spectral domain, and the noise characteristics are presented. Suggestions for the improved design are discussed.

Good Abundances from Bad Spectra: II. Application and a New Stellar Color-Temperature Calibration

Science.gov (United States)

Jones, J. Bryn; Wyse, Rosemary F. G.; Gilmore, Gerard

1995-07-01

Stellar spectra derived from current multiple-object fiber-fed spectroscopic radial-velocity surveys, of the type feasible with, among other examples, AUTOFIB, 2dF, HYDRA, NESSIE, and the Sloan survey, differ significantly from those traditionally used for determination of stellar abundances. The spectra tend to be of moderate resolution (around 1 A) and signal-to-noise ratio (around 10-20 per resolution element), and cannot usually have reliable continuum shapes determined over wavelength ranges in excess of a few tens of Angstroms. Nonetheless, with care and a calibration of stellar effective temperature from photometry, independent of the spectroscopy, reliable iron abundances can be derived. We have developed techniques to extract true iron abundances and surface gravities from low signal-to-noise ratio, intermediate resolution spectra of G-type stars in the 4000-5000A wavelength region. The theoretical basis and calibration using synthetic spectra are described in detail in another paper (Jones, Gilmore and Wyse, 1995). The practical application of these techniques to observational data, which requires some modification from the ideal case of synthetic data, is given in the present paper. An externally-derived estimate of stellar effective temperature is required in order to constrain parameter space sufficiently; a new derivation of the V-I effective temperature relation is thus an integral part of the analysis presented here. We have derived this relationship from analysis of available relevant data for metal-poor G dwarfs, the first such calibration. We test and calibrate our techniques by analysis of spectra of the twilight sky, of member stars of the cluster M67, and of a set of field stars of known metallicity. We show that this method, combined with our new color-temperature calibration, can provide true iron abundances, with an uncertainty of less than 0.2 dex over the range of metallicty found in the Galactic thick and thin disks, from spectra

Cryogenic Pressure Calibration Facility Using a Cold Force Reference

CERN Document Server

Bager, T; Métral, L

1999-01-01

Presently various commercial cryogenic pressure sensors are being investigated for installation in the LHC collider, they will eventually be used to assess that the magnets are fully immersed in liquid and to monitor fast pressure transients. In the framework of this selection procedure a cryogenic pressue calibration facility has been designed and built; it is based on a cryogenic primary pressure reference made of a bellows that converts the pressure into a force measurement. For that a shaft transfers this force to a precision force transducer at room temperature. Knowing the liquid bath pessure and the surface area of the bellows the pressure applied to the transducers under calibration is calculated; corrections due to thermal contraction are introduced. To avoid loss of force in the bellows wall its length is maintained constant; a cold capacitive displacement sensor measures this. The calibration temperature covers 1.5 K to 4.2 K and the pressure 0 to 20 bar. In contrast with more classical techniques ...

A Fiber Bragg grating based tilt sensor suitable for constant temperature room

International Nuclear Information System (INIS)

Tang, Guoyu; Wei, Jue; Zhou, Wei; Wu, Mingyu; Yang, Meichao; Xie, Ruijun; Xu, Xiaofeng

2015-01-01

Constant-temperature rooms have been widely used in industrial production, quality testing, and research laboratories. This paper proposes a high-precision tilt sensor suitable for a constant- temperature room, which has achieved a wide-range power change while the fiber Bragg grating (FBG) reflection peak wavelength shifted very little, thereby demonstrating a novel method for obtaining a high-precision tilt sensor. This paper also studies the effect of the reflection peak on measurement precision. The proposed sensor can distinguish the direction of tilt with an excellent sensitivity of 403 dBm/° and a highest achievable resolution of 2.481 × 10 −5 ° (that is, 0.08% of the measuring range). (paper)

An investigation of automatic exposure control calibration for chest imaging with a computed radiography system

International Nuclear Information System (INIS)

Moore, C S; Wood, T J; Beavis, A W; Saunderson, J R; Avery, G; Balcam, S; Needler, L

2014-01-01

The purpose of this study was to examine the use of three physical image quality metrics in the calibration of an automatic exposure control (AEC) device for chest radiography with a computed radiography (CR) imaging system. The metrics assessed were signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and mean effective noise equivalent quanta (eNEQ m ), all measured using a uniform chest phantom. Subsequent calibration curves were derived to ensure each metric was held constant across the tube voltage range. Each curve was assessed for its clinical appropriateness by generating computer simulated chest images with correct detector air kermas for each tube voltage, and grading these against reference images which were reconstructed at detector air kermas correct for the constant detector dose indicator (DDI) curve currently programmed into the AEC device. All simulated chest images contained clinically realistic projected anatomy and anatomical noise and were scored by experienced image evaluators. Constant DDI and CNR curves do not appear to provide optimized performance across the diagnostic energy range. Conversely, constant eNEQ m  and SNR do appear to provide optimized performance, with the latter being the preferred calibration metric given as it is easier to measure in practice. Medical physicists may use the SNR image quality metric described here when setting up and optimizing AEC devices for chest radiography CR systems with a degree of confidence that resulting clinical image quality will be adequate for the required clinical task. However, this must be done with close cooperation of expert image evaluators, to ensure appropriate levels of detector air kerma. (paper)

An investigation of automatic exposure control calibration for chest imaging with a computed radiography system.

Science.gov (United States)

Moore, C S; Wood, T J; Avery, G; Balcam, S; Needler, L; Beavis, A W; Saunderson, J R

2014-05-07

The purpose of this study was to examine the use of three physical image quality metrics in the calibration of an automatic exposure control (AEC) device for chest radiography with a computed radiography (CR) imaging system. The metrics assessed were signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and mean effective noise equivalent quanta (eNEQm), all measured using a uniform chest phantom. Subsequent calibration curves were derived to ensure each metric was held constant across the tube voltage range. Each curve was assessed for its clinical appropriateness by generating computer simulated chest images with correct detector air kermas for each tube voltage, and grading these against reference images which were reconstructed at detector air kermas correct for the constant detector dose indicator (DDI) curve currently programmed into the AEC device. All simulated chest images contained clinically realistic projected anatomy and anatomical noise and were scored by experienced image evaluators. Constant DDI and CNR curves do not appear to provide optimized performance across the diagnostic energy range. Conversely, constant eNEQm and SNR do appear to provide optimized performance, with the latter being the preferred calibration metric given as it is easier to measure in practice. Medical physicists may use the SNR image quality metric described here when setting up and optimizing AEC devices for chest radiography CR systems with a degree of confidence that resulting clinical image quality will be adequate for the required clinical task. However, this must be done with close cooperation of expert image evaluators, to ensure appropriate levels of detector air kerma.

Short wavelength FELS

International Nuclear Information System (INIS)

Sheffield, R.L.

1991-01-01

The generation of coherent ultraviolet and shorter wavelength light is presently limited to synchrotron sources. The recent progress in the development of brighter electron beams enables the use of much lower energy electron rf linacs to reach short-wavelengths than previously considered possible. This paper will summarize the present results obtained with synchrotron sources, review proposed short- wavelength FEL designs and then present a new design which is capable of over an order of magnitude higher power to the extreme ultraviolet. 17 refs., 10 figs

Short wavelength FELS

Energy Technology Data Exchange (ETDEWEB)

Sheffield, R.L.

1991-01-01

The generation of coherent ultraviolet and shorter wavelength light is presently limited to synchrotron sources. The recent progress in the development of brighter electron beams enables the use of much lower energy electron rf linacs to reach short-wavelengths than previously considered possible. This paper will summarize the present results obtained with synchrotron sources, review proposed short- wavelength FEL designs and then present a new design which is capable of over an order of magnitude higher power to the extreme ultraviolet. 17 refs., 10 figs.

On the possiblity of using vertically pointing Central Laser Facilities to calibrate the Cherenkov Telescope Array

International Nuclear Information System (INIS)

Gaug, Markus

2014-01-01

A Central Laser Facility is a system composed of a laser placed at a certain distance from a light-detector array, emitting fast light pulses, typically in the vertical direction, with the aim to calibrate that array. During calibration runs, all detectors are pointed towards the same portion of the laser beam at a given altitude. Central Laser Facilities are used for various currently operating ultra-high-energy cosmic ray and imaging atmospheric Cherenkov telescope arrays. In view of the future Cherenkov Telescope Array, a similar device could provide a fast calibration of the whole installation at different wavelengths. The relative precision (i.e. each individual telescope with respect to the rest of the array is expected) to be better than 5%, while an absolute calibration should reach a precisions of 6–11%, if certain design requirements are met. Additionally, a preciser monitoring of the sensitivity of each telescope can be made on time-scales of days to years

Long-wavelength Radar Studies of the Lunar Maria

Science.gov (United States)

Campbell, Bruce A.; Hawke, B. Ray; Thompson, Thomas W.

1995-01-01

Radar measurements at 70 cm and 7.5 m wavelengths provide insight into the structure and chemical properties of the upper 5-100 m of the lunar regolith and crust. Past work has identified a number of anomalous regions and changes in echo strength, some attributed to differences in titanium content. There has been little opportunity, however, to compare calibrated long-wavelength backscatter among different units or to theoretical model results. We combine recent high-resolution (3-5 km) 70-cm radar data for the nearside with earlier calibrated full-disk observations to provide a reasonable estimate of the true lunar backscatter coefficient. These data are tested against models for quasi-specular scattering from the surface, echoes from a buried substrate, and Mie scattering from surface and buried rocks. We find that 70 cm echoes likely arise from Mie scattering by distributed rocks within the soil, consistent with earlier hypotheses. Returns from a buried substrate would provide a plausible fit to the observations only if the regolith depth were 3 m or less and varied little across the maria. Depolarized echoes are due to some combination of single and multiple scattering events, but it appears that single scattering alone could account for the observed echo power, based on comparisons with terrestrial rocky surfaces. Backscatter strength from the regolith is most strongly affected by the loss tangent, whose variation with mineral content is still poorly defined. We compared the backscatter values for the mare deposits to the oxide contents inferred from spectral ratio methods, and found that in general the unit boundaries evident in radar images closely follow those seen in color difference images. The 70-cm data are not well correlated with TiO2 values found using the Charette relationship nor with Fe abundances derived from Clementine observations. The lack of a relationship between radar echo and Fe content is reasonable given the distribution of iron among

A 12 GHz wavelength spacing multi-wavelength laser source for wireless communication systems

Science.gov (United States)

Peng, P. C.; Shiu, R. K.; Bitew, M. A.; Chang, T. L.; Lai, C. H.; Junior, J. I.

2017-08-01

This paper presents a multi-wavelength laser source with 12 GHz wavelength spacing based on a single distributed feedback laser. A light wave generated from the distributed feedback laser is fed into a frequency shifter loop consisting of 50:50 coupler, dual-parallel Mach-Zehnder modulator, optical amplifier, optical filter, and polarization controller. The frequency of the input wavelength is shifted and then re-injected into the frequency shifter loop. By re-injecting the shifted wavelengths multiple times, we have generated 84 optical carriers with 12 GHz wavelength spacing and stable output power. For each channel, two wavelengths are modulated by a wireless data using the phase modulator and transmitted through a 25 km single mode fiber. In contrast to previously developed schemes, the proposed laser source does not incur DC bias drift problem. Moreover, it is a good candidate for radio-over-fiber systems to support multiple users using a single distributed feedback laser.

Calibration of CR-39 for radon-related parameters using sealed cup technique

International Nuclear Information System (INIS)

Abo-Elmagd, M.; Daif, M. M.

2010-01-01

Effective radium content, mass and areal radon exhalation rates of soil and rock samples are important radon-related parameters and can be used as a better indicator of radon risk. A sealed cup fitted to a CR-39 detector and to the sample under measurement is an advantageous passive device for the measurement of these parameters. The main factors affecting the results are the detector calibration factor and the sample weight. The results of an active technique (Lucas cell) and the CR-39 detector have been found to be correlated resulting in a reliable detector calibration factor. The result illustrates the dependence of the CR-39 calibration factor with the sample weight which is difficult to use in practice, because each sample weight has its own calibration factor of CR-39. It is reported to demonstrate the advantage of a back diffusion correction. After correcting the results for back diffusion effects, one obtains an approximately constant calibration factor for the sample volumes up to one-third the total sealed cup volume. For this condition the calibration factor is equal to 0.237 track cm -2 per Bq m -3 d with about 1% uncertainty. (authors)

High-precision reflectivity measurements: improvements in the calibration procedure

Science.gov (United States)

Jupe, Marco; Grossmann, Florian; Starke, Kai; Ristau, Detlev

2003-05-01

The development of high quality optical components is heavily depending on precise characterization procedures. The reflectance and transmittance of laser components are the most important parameters for advanced laser applications. In the industrial fabrication of optical coatings, quality management is generally insured by spectral photometric methods according to ISO/DIS 15386 on a medium level of accuracy. Especially for high reflecting mirrors, a severe discrepancy in the determination of the absolute reflectivity can be found for spectral photometric procedures. In the first part of the CHOCLAB project, a method for measuring reflectance and transmittance with an enhanced precision was developed, which is described in ISO/WD 13697. In the second part of the CHOCLAB project, the evaluation and optimization for the presented method is scheduled. Within this framework international Round-Robin experiment is currently in progress. During this Round-Robin experiment, distinct deviations could be observed between the results of high precision measurement facilities of different partners. Based on the extended experiments, the inhomogeneity of the sample reflectivity was identified as one important origin for the deviation. Consequently, this inhomogeneity is also influencing the calibration procedure. Therefore, a method was developed that allows the calibration of the chopper blade using always the same position on the reference mirror. During the investigations, the homogeneity of several samples was characterized by a surface mapping procedure for 1064 nm. The measurement facility was extended to the additional wavelength 532 nm and a similar set-up was assembled at 10.6 μm. The high precision reflectivity procedure at the mentioned wavelengths is demonstrated for exemplary measurements.

Solar Cell Calibration and Measurement Techniques

Science.gov (United States)

Bailey, Sheila; Brinker, Dave; Curtis, Henry; Jenkins, Phillip; Scheiman, Dave

2004-01-01

The increasing complexity of space solar cells and the increasing international markets for both cells and arrays has resulted in workshops jointly sponsored by NASDA, ESA and NASA. These workshops are designed to obtain international agreement on standardized values for the AMO spectrum and constant, recommend laboratory measurement practices and establish a set of protocols for international comparison of laboratory measurements. A working draft of an ISO standard, WD15387, "Requirements for Measurement and Calibration Procedures for Space Solar Cells" was discussed with a focus on the scope of the document, a definition of primary standard cell, and required error analysis for all measurement techniques. Working groups addressed the issues of Air Mass Zero (AMO) solar constant and spectrum, laboratory measurement techniques, and te international round robin methodology. A summary is presented of the current state of each area and the formulation of the ISO document.

Calibration

International Nuclear Information System (INIS)

Greacen, E.L.; Correll, R.L.; Cunningham, R.B.; Johns, G.G.; Nicolls, K.D.

1981-01-01

Procedures common to different methods of calibration of neutron moisture meters are outlined and laboratory and field calibration methods compared. Gross errors which arise from faulty calibration techniques are described. The count rate can be affected by the dry bulk density of the soil, the volumetric content of constitutional hydrogen and other chemical components of the soil and soil solution. Calibration is further complicated by the fact that the neutron meter responds more strongly to the soil properties close to the detector and source. The differences in slope of calibration curves for different soils can be as much as 40%

The pre-flight calibration setup of the instrument SIMBIO-SYS onboard the mission BepiColombo

Science.gov (United States)

Poulet, F.; Rodriguez-Ferreira, J.; Arondel, A.; Dassas, K.; Eng, P.; Lami, P.; Langevin, Y.; Longval, Y.; Pradel, P.; Dami, M.

2015-11-01

BepiColombo, an European Space Agency (ESA) mission being conducted in cooperation with the Japan space agency, will explore Mercury with a set of eleven instruments onboard the spacecraft Mercury Planetary Orbiter (MPO). Among them, SIMBIO-SYS (Spectrometers and Imagers for MPO BepiColombo Integrated Observatory SYStem) is a complex instrument that will provide images and spectra in the 400-2000 nm wavelength range of the entire surface of Mercury. Pre-flight calibration of the SYMBIO-SYS instrument is mandatory for reliable scientific interpretation of images and spectra returned from the planet Mercury. This paper presents the calibration device designed and implemented for the specific requirements of this instrument. It mainly consists of a thermal vacuum chamber simulating the space environment, an optical bench collecting calibration sources and optical elements that simulate the conditions of Mercury observations, mechanical interfaces used for positioning the three channels inside the vacuum chamber, thermal interfaces to explore the operating temperatures, computer interfaces that allow to communicate with both the instrument and the calibration elements and synchronize the calibrations sequences with the status of the calibration device. As the major goal is the characterization of the radiometric performances of the three channels of SIMBIO-SYS, radiometric performances of the test setup evaluated by simulations and measurements are emphasized.

WDM cross-connect cascade based on all-optical wavelength converters for routing and wavelength slot interchanging using a reduced number of internal wavelengths

DEFF Research Database (Denmark)

Pedersen, Rune Johan Skullerud; Mikkelsen, Benny; Jørgensen, Bo Foged

1998-01-01

interchanging can be used to create a robust and nonblocking OXC. However, for an OXC with n fiber inlets each carrying m wavelengths the OXC requires n×m internal wavelengths, which constrains the size of the cross-connect. In this paper we therefore propose and demonstrate an architecture that uses a reduced......Optical transport layers need rearrangeable wavelength-division multiplexing optical cross-connects (OXCs) to increase the capacity and flexibility of the network. It has previously been shown that a cross-connect based on all-optical wavelength converters for routing as well as wavelength slot...... set of internal wavelengths without sacrificing cross-connecting capabilities. By inserting a partly equipped OXC with the new architecture in a 10-Gbit/s re-circulating loop setup we demonstrate the possibility of cascading up to ten OXCs. Furthermore, we investigate the regenerating effect...

IAEA workshop/seminar on calibration procedures in dosimetry, Quito, 6-24 October 1986

International Nuclear Information System (INIS)

1987-01-01

The International Atomic Energy Agency in co-operation with the Ecuadorian Atomic Energy Commission organized a workshop and seminar on calibration procedures in dosimetry at the SSDL Quito, 6 to 24 October 1986. All calibration laboratories in the Latin American region were invited to participate. The purpose of the workshop were calibration exercises with therapy-level and protection-level secondary standards at various calibration qualities, discussions on progress made in the different SSDLs in the region and delivering lectures on pertinent subjects. A total of 15 Secondary Standards (10 therapy-level and 5 protection-level) were brought along by the participants and 35 calibration comparisons were performed with those having a valid calibration factor. Thirty-three determinations of calibration factors were performed for secondary standards not having had a calibration before. Twelve different calibration qualities were available (Cobalt-60 and X-rays) and Agency's Secondary Standards traceable to BIPM were the reference standards. The participants were divided into two working groups, each one week and each group into two sub-groups. Both irradiation bunkers were used simultaneously. The one houses the teletherapy Cobalt-60 unit and the protection-level Cobalt-60 irradiator, the other one the constant potential X-ray machine with maximum generating potential of 320 KV and suitable for both therapy-level as well as protection-level calibrations. Due to the heavy workload and limited time available some nightshifts were required to accomplish the requested calibration comparisons

Calibrating an ellipsometer using x-ray reflectivity

International Nuclear Information System (INIS)

Richter, Andrew; Guico, Rodney; Wang, Jin

2001-01-01

X-ray reflectivity has been used to find the optical refractive index of polymer thin film in order to calibrate a Stokes ellipsometer for film thickness measurements during the deposition procedure. A thin, spun-cast film of poly(tert-butyl acrylate) (PtBA) was made with a film thickness of ∼500 {angstrom}. An x-ray reflectivity measurement was taken and the data were fit to determine the thickness of the PtBA film and the underlying silicon--oxide layer. This measurement was then used to calculate the optical refractive index for PtBA at the ellipsometer wavelength. Using this value for the refractive index subsequently allowed us to determine the film thickness for a series of PtBA films made by using a number of polymer solution concentrations resulting in film thickness ranging from 100 to 1300 {angstrom}. These film thicknesses were found to be generally the same as those found using x-ray reflectivity. The success of this procedure suggests a useful method for calibrating an ellipsometer for fast in-lab measurements, especially on ultrathin films when simultaneous determination of the film thickness and the refractive index is less reliable

Calibration of ratemeters used for gamma radiation detection

International Nuclear Information System (INIS)

Hantanirina, P.A.

2017-01-01

The Secondary Standard Dosimetry Laboratory (SSDL) of INSTN-Madagascar is in charge of the calibration of every dosimetry measurement instrument in hospitals and companies using radioactive sources in Madagascar. It has a secondary standard delivered and calibrated by a Primary Standard Laboratory in Dosimetry (PSLD). This standard is used to compare its reference values with those displayed on the instruments to be calibrated. During our training period, three (3) ratemeters were calibrated, the Graetz X5DE, the Graetz X5C and the Identifinder 2. We have determined the calibration factor for every ratemeter by doing calculation with the reference value. By using the three surveymeters for direct radiations measurements, it has been found that the difference between the displayed values and the real values for every ratemeter does not exceed the tolerance limit which is 20 %. Then we can conclude that these ratemeters are still in good condition of functioning. Concerning the calibration factor curve N_k with the K_a_i_r , we can observe that for the Graetz X5C ratemeter, this curve is almost constant. As well as for the linearity, it is still the Graetz X5C ratemeter which is linear almost integrally for the measured and calculated dose rate values. So we can say that this ratemeter is the most recommended for the radiations measurements.This work which has been carried within the framework of collaboration between the section PNAE (Physique Nucléaire Appliquée et Environnement) of the University of Antananarivo and INSTN-Madagascar has been a good and rewarding experience which allowed us to put into practice all knowledges acquired during our years of studies. [fr

Influence of Er:YAG and Nd:YAG wavelengths on laser-induced breakdown spectroscopy measurements under air or helium atmosphere

International Nuclear Information System (INIS)

Detalle, Vincent; Sabsabi, Mohamad; St-Onge, Louis; Hamel, Andre; Heon, Rene

2003-01-01

Laser-induced breakdown spectroscopy (LIBS) is widely dependent on the conditions of its implementation in terms of laser characteristics (wavelength, energy, and pulse duration), focusing conditions, and surrounding gas. In this study two wavelengths, 1.06 and 2.94 μm, obtained with Nd:YAG and Er:YAG lasers, respectively, were used for LIBS analysis of aluminum alloy samples in two conditions of surrounding gas. The influence of the laser wavelength on the laser-produced plasma was studied for the same irradiance by use of air or helium as a buffer gas at atmospheric pressure. We used measurements of light emission to determine the temporally resolved space-averaged electron density and plasma temperature in the laser-induced plasma. We also examined the effect of laser wavelength in two different ambient conditions in terms of spectrochemical analysis by LIBS. The results indicate that the effect of the surrounding gas depends on the laser wavelength and the use of an Er:YAG laser could increase linearity by limiting the leveling in the calibration curve for some elements in aluminum alloys. There is also a significant difference between the plasma induced by the two lasers in terms of electron density and plasma temperature

Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations for solvent-based carbon capture. Part 2: Chemical absorption across a wetted wall column: Original Research Article: Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations

Energy Technology Data Exchange (ETDEWEB)

Wang, Chao [Pacific Northwest National Laboratory, Physical and Computational Sciences Directorate, Richland WA; Xu, Zhijie [Pacific Northwest National Laboratory, Physical and Computational Sciences Directorate, Richland WA; Lai, Kevin [Pacific Northwest National Laboratory, Physical and Computational Sciences Directorate, Richland WA; Whyatt, Greg [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA; Marcy, Peter W. [Los Alamos National Laboratory, Statistical Sciences Group, Los Alamos NM; Sun, Xin [Oak Ridge National Laboratory, Energy and Transportation Science Division, Oak Ridge TN

2017-10-24

The first part of this paper (Part 1) presents a numerical model for non-reactive physical mass transfer across a wetted wall column (WWC). In Part 2, we improved the existing computational fluid dynamics (CFD) model to simulate chemical absorption occurring in a WWC as a bench-scale study of solvent-based carbon dioxide (CO2) capture. To generate data for WWC model validation, CO2 mass transfer across a monoethanolamine (MEA) solvent was first measured on a WWC experimental apparatus. The numerical model developed in this work has the ability to account for both chemical absorption and desorption of CO2 in MEA. In addition, the overall mass transfer coefficient predicted using traditional/empirical correlations is conducted and compared with CFD prediction results for both steady and wavy falling films. A Bayesian statistical calibration algorithm is adopted to calibrate the reaction rate constants in chemical absorption/desorption of CO2 across a falling film of MEA. The posterior distributions of the two transport properties, i.e., Henry’s constant and gas diffusivity in the non-reacting nitrous oxide (N2O)/MEA system obtained from Part 1 of this study, serves as priors for the calibration of CO2 reaction rate constants after using the N2O/CO2 analogy method. The calibrated model can be used to predict the CO2 mass transfer in a WWC for a wider range of operating conditions.

At-wavelength metrology of x-ray optics at Diamond Light Source

Science.gov (United States)

Wang, Hongchang; Berujon, Sebastien; Sutter, John; Alcock, Simon G.; Sawhney, Kawal

2014-09-01

Modern, third-generation synchrotron radiation sources provide coherent and extremely bright beams of X-ray radiation. The successful exploitation of such beams depends to a significant extent on imperfections and misalignment of the optics employed on the beamlines. This issue becomes even more critical with the increasing use of active optics, and the desire to achieve diffraction-limited and coherence-preserving X-ray beams. In recent years, significant progress has been made to improve optic testing and optimization techniques, especially those using X-rays for so-called atwavelength metrology. These in-situ and at-wavelength metrology methods can be used not only to optimize the performance of X-ray optics, but also to correct and minimize the collective distortions of upstream beamline optics, including monochromators, and transmission windows. An overview of at-wavelength metrology techniques implemented at Diamond Light Source is presented, including grating interferometry and X-ray near-field speckle based techniques. Representative examples of the application of these techniques are also given, including in-situ and atwavelength calibration and optimization of: active, piezo bimorph mirrors; Kirkpatrick-Baez (KB) mirrors; and refractive optics such as compound refractive lenses.

Precise calibration of few-cycle laser pulses with atomic hydrogen

Science.gov (United States)

Wallace, W. C.; Kielpinski, D.; Litvinyuk, I. V.; Sang, R. T.

2017-12-01

Interaction of atoms and molecules with strong electric fields is a fundamental process in many fields of research, particularly in the emerging field of attosecond science. Therefore, understanding the physics underpinning those interactions is of significant interest to the scientific community. One crucial step in this understanding is accurate knowledge of the few-cycle laser field driving the process. Atomic hydrogen (H), the simplest of all atomic species, plays a key role in benchmarking strong-field processes. Its wide-spread use as a testbed for theoretical calculations allows the comparison of approximate theoretical models against nearly-perfect numerical solutions of the three-dimensional time-dependent Schrödinger equation. Until recently, relatively little experimental data in atomic H was available for comparison to these models, and was due mostly due to the difficulty in the construction and use of atomic H sources. Here, we review our most recent experimental results from atomic H interaction with few-cycle laser pulses and how they have been used to calibrate important laser pulse parameters such as peak intensity and the carrier-envelope phase (CEP). Quantitative agreement between experimental data and theoretical predictions for atomic H has been obtained at the 10% uncertainty level, allowing for accurate laser calibration intensity at the 1% level. Using this calibration in atomic H, both accurate CEP data and an intensity calibration standard have been obtained Ar, Kr, and Xe; such gases are in common use for strong-field experiments. This calibration standard can be used by any laboratory using few-cycle pulses in the 1014 W cm-2 intensity regime centered at 800 nm wavelength to accurately calibrate their peak laser intensity to within few-percent precision.

Comments on: Accuracy of Raman Lidar Water Vapor Calibration and its Applicability to Long-Term Measurements

Science.gov (United States)

Whiteman, David N.; Venable, Demetrius; Landulfo, Eduardo

2012-01-01

In a recent publication, LeBlanc and McDermid proposed a hybrid calibration technique for Raman water vapor lidar involving a tungsten lamp and radiosondes. Measurements made with the lidar telescope viewing the calibration lamp were used to stabilize the lidar calibration determined by comparison with radiosonde. The technique provided a significantly more stable calibration constant than radiosondes used alone. The technique involves the use of a calibration lamp in a fixed position in front of the lidar receiver aperture. We examine this configuration and find that such a configuration likely does not properly sample the full lidar system optical efficiency. While the technique is a useful addition to the use of radiosondes alone for lidar calibration, it is important to understand the scenarios under which it will not provide an accurate quantification of system optical efficiency changes. We offer examples of these scenarios.

High-Sensitivity AGN Polarimetry at Sub-Millimeter Wavelengths

Directory of Open Access Journals (Sweden)

Ivan Martí-Vidal

2017-10-01

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

Standard test methods for chemical analysis of ceramic whiteware materials using wavelength dispersive X-Ray fluorescence spectrometry

CERN Document Server

American Society for Testing and Materials. Philadelphia

2004-01-01

1.1 These test methods cover the determination of ten major elements (SiO2, Al2O3, Fe2O3, MgO, CaO, Na2O, K2O, TiO2, P2O5, MnO, and LOI in ceramic whitewares clays and minerals using wavelength dispersive X-ray fluorescence spectrometry (WDXRF). The sample is first ignited, then fused with lithium tetraborate and the resultant glass disc is introduced into a wavelength dispersive X-ray spectrometer. The disc is irradiated with X-rays from an X-ray tube. X-ray photons emitted by the elements in the samples are counted and concentrations determined using previously prepared calibration standards. (1) In addition to 10 major elements, the method provides a gravimetric loss-on-ignition. Note 1—Much of the text of this test method is derived directly from Major element analysis by wavelength dispersive X-ray fluorescence spectrometry, included in Ref (1). 1.2 Interferences, with analysis by WDXRF, may result from mineralogical or other structural effects, line overlaps, and matrix effects. The structure of the...

Effective constants for wave propagation through partially saturated porous media

International Nuclear Information System (INIS)

Berryman, J.G.; Thigpen, L.

1985-01-01

The multipole scattering coefficients for elastic wave scattering from a spherical inhomogeneity in a fluid-saturated porous medium have been calculated. These coefficients may be used to obtain estimates of the effective macroscopic constants for long-wavelength propagation of elastic waves through partially saturated media. If the volume average of the single scattering from spherical bubbles of gas and liquid is required to vanish, the resulting equations determine the effective bulk modulus, density, and viscosity of the multiphase fluid filling the pores. The formula for the effective viscosity during compressional wave excitation is apparently new

Calibration of atomic force microscope cantilevers using standard and inverted static methods assisted by FIB-milled spatial markers

International Nuclear Information System (INIS)

Slattery, Ashley D; Blanch, Adam J; Quinton, Jamie S; Gibson, Christopher T

2013-01-01

Static methods to determine the spring constant of AFM cantilevers have been widely used in the scientific community since the importance of such calibration techniques was established nearly 20 years ago. The most commonly used static techniques involve loading a trial cantilever with a known force by pressing it against a pre-calibrated standard or reference cantilever. These reference cantilever methods have a number of sources of uncertainty, which include the uncertainty in the measured spring constant of the standard cantilever, the exact position of the loading point on the reference cantilever and how closely the spring constant of the trial and reference cantilever match. We present a technique that enables users to minimize these uncertainties by creating spatial markers on reference cantilevers using a focused ion beam (FIB). We demonstrate that by combining FIB spatial markers with an inverted reference cantilever method, AFM cantilevers can be accurately calibrated without the tip of the test cantilever contacting a surface. This work also demonstrates that for V-shaped cantilevers it is possible to determine the precise loading position by AFM imaging the section of the cantilever where the two arms join. Removing tip-to-surface contact in both the reference cantilever method and sensitivity calibration is a significant improvement, since this is an important consideration for AFM users that require the imaging tip to remain in pristine condition before commencing measurements. Uncertainties of between 5 and 10% are routinely achievable with these methods. (paper)

Design of laser diode driver with constant current and temperature control system

Science.gov (United States)

Wang, Ming-cai; Yang, Kai-yong; Wang, Zhi-guo; Fan, Zhen-fang

2017-10-01

A laser Diode (LD) driver with constant current and temperature control system is designed according to the LD working characteristics. We deeply researched the protection circuit and temperature control circuit based on thermos-electric cooler(TEC) cooling circuit and PID algorithm. The driver could realize constant current output and achieve stable temperature control of LD. Real-time feedback control method was adopted in the temperature control system to make LD work on its best temperature point. The output power variety and output wavelength shift of LD caused by current and temperature instability were decreased. Furthermore, the driving current and working temperature is adjustable according to specific requirements. The experiment result showed that the developed LD driver meets the characteristics of LD.

A study on improvement of measurement capability for gravimetric flowmeter calibrator

International Nuclear Information System (INIS)

Lee, Dong Keun; Park, Jong Ho

2009-01-01

The calibration of flowmeter is a very important procedure to set up traceability from the national or international standards. The uncertainty of flow measurement defines reliability for measurement results. The uncertainty of gravimetric method combines uncertainties of each independent variable, including mass, time, water density, air density and the density of dead weight. In this study, it has been found that the uncertainties of mass and time measurement in the gravimetric method have dominant influence on the total measurement uncertainty. After improvements of a constant head tank and a diverter, the best measurement capability for K-water's calibration facility has been reached less than 0.1%.

Wavelength conversion devices

DEFF Research Database (Denmark)

Mikkelsen, Benny; Durhuus, Terji; Jørgensen, Carsten

1996-01-01

system requirements. The ideal wavelength converter should be transparent to the bit rate and signal format and provide an unchirped output signal with both a high extinction ratio and a large signal-to-noise ratio. It should allow conversion to both shorter and longer wavelengths with equal performance...

Implications of a wavelength dependent PSF for weak lensing measurements.

Science.gov (United States)

Eriksen, Martin; Hoekstra, Henk

2018-05-01

The convolution of galaxy images by the point-spread function (PSF) is the dominant source of bias for weak gravitational lensing studies, and an accurate estimate of the PSF is required to obtain unbiased shape measurements. The PSF estimate for a galaxy depends on its spectral energy distribution (SED), because the instrumental PSF is generally a function of the wavelength. In this paper we explore various approaches to determine the resulting `effective' PSF using broad-band data. Considering the Euclid mission as a reference, we find that standard SED template fitting methods result in biases that depend on source redshift, although this may be remedied if the algorithms can be optimised for this purpose. Using a machine-learning algorithm we show that, at least in principle, the required accuracy can be achieved with the current survey parameters. It is also possible to account for the correlations between photometric redshift and PSF estimates that arise from the use of the same photometry. We explore the impact of errors in photometric calibration, errors in the assumed wavelength dependence of the PSF model and limitations of the adopted template libraries. Our results indicate that the required accuracy for Euclid can be achieved using the data that are planned to determine photometric redshifts.

Investigation of optimized experimental parameters including laser wavelength for boron measurement in photovoltaic grade silicon using laser-induced breakdown spectroscopy

International Nuclear Information System (INIS)

Darwiche, S.; Benmansour, M.; Eliezer, N.; Morvan, D.

2010-01-01

The quantification of boron and other impurities in photovoltaic grade silicon was investigated using the LIBS technique with attention to the laser wavelength employed, temporal parameters, and the nature of the ambient gas. The laser wavelength was found to have a moderate effect on the performance of the process, while the type of purge gas and temporal parameters had a strong effect on the signal-to-background ratio (SBR) of the boron spectral emission, which was used to determine the boron concentration in silicon. The three parameters are not independent, meaning that for each different purge gas, different optimal temporal parameters are observed. Electron density was also calculated from Stark broadening of the 390.5 nm silicon emission line in order to better understand the different performances observed when using different gases and gating parameters. Calibration curves were made for boron measurement in silicon using certified standards with different purge gases while using the temporal parameters which had been optimized for that gas. By comparing the calibration curves, it was determined that argon is superior to helium or air for use as the analysis chamber purge gas with an UV laser.

The laser system for calibration and monotoring of the Opal jet chamber

International Nuclear Information System (INIS)

Biebel, O.; Boden, B.; Bug, S.; Eyring, A.; Fischer, H.M.; Geich-Gimbel, C.; Gross, S.; Knop, G.; Levegruen, S.; Maringer, G.; Mauer, E.; Maur, U.; Nellen, B.; Neumann, H.; Rollnik, A.; Schreiber, S.; Simon, A.; Thiebes, J.; Wolf, B.; Wuensch, B.; Boerner, H.; Breuker, H.; Hagemann, J.; Hauschild, M.; Heuer, R.D.; Karner, K.; Linser, G.; Runolfsson, O.; Seidl, W.; Voillat, D.; Wicht, P.; Schmitt, H. von der; Wagner, A.

1992-01-01

In this report we describe the construction and performance of the laser system which was used in Summer 1989 for the initial calibration of the OPAL jet chamber after installation on the LEP beam axis and which has served as a monitoring tool since then. Two Nd:YAG lasers are used to generate 48 high precision double beams which enter the chamber at fixed positions. The main features of the roughly 450 optical components are described and the beam alignment procedures are explained. Results are given for jet chamber calibration constants such as drift velocity, Lorentz angle, and residual sagittas. (orig.)

Calibration of the Dodewaard downcomer thermocouple cross-correlation flow-rate measurements

Energy Technology Data Exchange (ETDEWEB)

Stekelenburg, A J.C. [Technische Univ. Delft (Netherlands). Interfacultair Reactor Inst.; Hagen, T.H.J.J. van der [Technische Univ. Delft (Netherlands). Interfacultair Reactor Inst.; Akker, H.E.A. van den [Technische Univ. Delft (Netherlands). Lab. voor Fysische Technologie

1992-12-01

The cross-correlation flow measurement technique, applied for measuring the coolant flow rate in a nuclear reactor, was calibrated with the use of numerical simulations of turbulent flow. The three-dimensional domain was collapsed into two dimensions. With a two-dimensional calculation of steady-state flow with transient thermal characteristics the response of thermocouples to a temperature variation was calculated. By cross-correlating the calculated thermocouple responses, the link between total flow rate and measured transit times was made. Three calibration points were taken in the range of 579 kg/s to 1477 kg/s. In this range, the product of the calculated transit time and the mass flow-rate is constant up to +3.5% and -2.4%. The reliability of the calibration was estimated at {+-}4.6%. The influence of the inlet boundary conditions, and the modelling of the flow in the upper part of the downcomer channel on the calibration result is shown to be small. A measured velocity profile effect was successfully predicted. (orig.).

QED Based Calculation of the Fine Structure Constant

Energy Technology Data Exchange (ETDEWEB)

Lestone, John Paul [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-10-13

Quantum electrodynamics is complex and its associated mathematics can appear overwhelming for those not trained in this field. Here, semi-classical approaches are used to obtain a more intuitive feel for what causes electrostatics, and the anomalous magnetic moment of the electron. These intuitive arguments lead to a possible answer to the question of the nature of charge. Virtual photons, with a reduced wavelength of λ, are assumed to interact with isolated electrons with a cross section of πλ². This interaction is assumed to generate time-reversed virtual photons that are capable of seeking out and interacting with other electrons. This exchange of virtual photons between particles is assumed to generate and define the strength of electromagnetism. With the inclusion of near-field effects the model presented here gives a fine structure constant of ~1/137 and an anomalous magnetic moment of the electron of ~0.00116. These calculations support the possibility that near-field corrections are the key to understanding the numerical value of the dimensionless fine structure constant.

In Search of Easy-to-Use Methods for Calibrating ADCP's for Velocity and Discharge Measurements

Science.gov (United States)

Oberg, K.; ,

2002-01-01

A cost-effective procedure for calibrating acoustic Doppler current profilers (ADCP) in the field was presented. The advantages and disadvantages of various methods which are used for calibrating ADCP were discussed. The proposed method requires the use of differential global positioning system (DGPS) with sub-meter accuracy and standard software for collecting ADCP data. The method involves traversing a long (400-800 meter) course at a constant compass heading and speed, while collecting simultaneous DGPS and ADCP data.

Synthesis, Characterization and Optical Constants of Silicon Oxycarbide

Directory of Open Access Journals (Sweden)

Memon Faisal Ahmed

2017-01-01

Full Text Available High refractive index glasses are preferred in integrated photonics applications to realize higher integration scale of passive devices. With a refractive index that can be tuned between SiO2 (1.45 and a-SiC (3.2, silicon oxycarbide SiOC offers this flexibility. In the present work, silicon oxycarbide thin films from 0.1 – 2.0 μm thickness are synthesized by reactive radio frequency magnetron sputtering a silicon carbide SiC target in a controlled argon and oxygen environment. The refractive index n and material extinction coefficient k of the silicon oxycarbide films are acquired with variable angle spectroscopic ellipsometry over the UV-Vis-NIR wavelength range. Keeping argon and oxygen gases in the constant ratio, the refractive index n is found in the range from 1.41 to 1.93 at 600 nm which is almost linearly dependent on RF power of sputtering. The material extinction coefficient k has been estimated to be less than 10-4 for the deposited silicon oxycarbide films in the visible and near-infrared wavelength regions. Morphological and structural characterizations with SEM and XRD confirms the amorphous phase of the SiOC films.

A New Approach for Checking and Complementing CALIPSO Lidar Calibration

Science.gov (United States)

Josset, Damien B.; Vaughan, Mark A.; Hu, Yongxiang; Avery, Melody A.; Powell, Kathleen A.; Hunt, William H.; Winker, David M.; Pelon, Jacques; Trepte, Charles R.; Lucker, Patricia L.;

Evaluation of the Use of Dark and Bright Targets for the In-Flight Calibration of AVIRIS

Science.gov (United States)

Thome, K.; Parada, R.; Schiller, S.; Conel, J.; LaMarr, J.

1998-01-01

During a field campaign at Lake Tahoe on June 22, 1995, calibrations of AVIRIS were attempted using both the reflectance-based and radiance-based methods. This experiment shows that the use of dark water targets to calibrate radiometric sensors can result in meaningful sensor characterization. In particular, the reflectance-based method shows promise towards meeting the desired 2-3% uncertainty levels for ocean color sensors since experimental agreement of better than 1.5% is found for the Lake Tahoe AVIRIS experiment. Similarly promising results were found from reflectance-based calibrations at Lunar Lake with large portions of the spectrum having less than a 5% difference between the reflectance-based predictions and the measured AVIRIS radiances. These results are still in the preliminary stage and it is likely that further study of this data set will lead to even better agreement. The results of the radiance-based calibration at Lake Tahoe are quite good at the shorter wavelengths where atmospheric scattering leads to larger signals and smaller effects of specularly reflected solar energy. The results also showed the sensitivity to radiometer pointing when using water targets for vicarious calibration.

Wavelength dependent deformation in a laser peened Ti-2.5Cu alloy

Energy Technology Data Exchange (ETDEWEB)

Umapathi, A., E-mail: umapathi.arimakula@gmail.com; Swaroop, S., E-mail: n.r.sathya.swaroop@gmail.com

2017-01-27

Laser peening without coating (LPwC) was performed on a Ti-2.5Cu alloy at wavelengths of 1064 and 532 nm and at a constant power density of approximately 7 GW cm{sup −2} with overlap rates of 53%, 63% and 73%. Surface softening due to thermal interaction of laser beam with material was observed till a depth of 500 µm (at 532 nm) and 200 µm (at 1064 nm), based on hardness data. This was corroborated (rather weakly) by residual stress analysis. In addition, softening due to mechanical effects (adiabatic heating) was observed in the bulk. Although there was an increase in mechanical softening with increase in overlap rates at 532 nm, it was observed, upon comparison with peened samples at 1064 nm, that the mechanical softening is a function of wavelength of radiation used for peening. It was observed that the onset of softening was earlier if the wavelength was shorter. Further, evidence of hardening in the form of twinning was found for the 1064 nm case while it was absent for the 532 nm case, for 73% overlap. The workhardened depth was more than 1000 µm, not observed in earlier studies based on residual stress analysis. The direct consequence of softening effect was found in the fatigue results. The fatigue life extended by a factor of 1.4 and 2.3 for the samples peened at 532 nm and 1064 nm respectively, consistent with the observed wavelength dependent onset of softening.

Linear chirped slope profile for spatial calibration in slope measuring deflectometry

Energy Technology Data Exchange (ETDEWEB)

Siewert, F., E-mail: frank.siewert@helmholtz-berlin.de; Zeschke, T. [Helmholtz Zentrum Berlin für Materialien und Energie, Institut für Nanometer Optik und Technologie, Albert-Einstein-Str. 15, 12489 Berlin (Germany); Arnold, T.; Paetzelt, H. [Leibnitz Institut für Oberflächen Modifizierung Leipzig e.V., IOM, Permoserstr. 15, 04318 Leipzig (Germany); Yashchuk, V. V. [Lawerence Berkeley National Laboratory, Advanced Light Source, 1 Cyclotron Road, Berkeley, California 94720 (United States)

2016-05-15

Slope measuring deflectometry is commonly used by the X-ray optics community to measure the long-spatial-wavelength surface figure error of optical components dedicated to guide and focus X-rays under grazing incidence condition at synchrotron and free electron laser beamlines. The best performing instruments of this kind are capable of absolute accuracy on the level of 30-50 nrad. However, the exact bandwidth of the measurements, determined at the higher spatial frequencies by the instrument’s spatial resolution, or more generally by the instrument’s modulation transfer function (MTF) is hard to determine. An MTF calibration method based on application of a test surface with a one-dimensional (1D) chirped height profile of constant amplitude was suggested in the past. In this work, we propose a new approach to designing the test surfaces with a 2D-chirped topography, specially optimized for MTF characterization of slope measuring instruments. The design of the developed MTF test samples based on the proposed linear chirped slope profiles (LCSPs) is free of the major drawback of the 1D chirped height profiles, where in the slope domain, the amplitude strongly increases with the local spatial frequency of the profile. We provide the details of fabrication of the LCSP samples. The results of first application of the developed test samples to measure the spatial resolution of the BESSY-NOM at different experimental arrangements are also presented and discussed.

In flight calibrations of Ibis/PICsIT

International Nuclear Information System (INIS)

Malaguti, G.; Di Cocco, G.; Foschini, L.; Stephen, J.B.; Bazzano, A.; Ubertini, P.; Bird, A.J.; Laurent, P.; Segreto, A.

2003-01-01

PICsIT (Pixellated Imaging Caesium Iodide Telescope) is the high energy detector of the IBIS telescope on-board the INTEGRAL satellite. It consists of 4096 independent detection units, ∼ 0.7 cm 2 in cross-section, operating in the energy range between 175 keV and 10 MeV. The intrinsically low signal to noise ratio in the gamma-ray astronomy domain implies very long observations, lasting 10 5 - 10 6 s. Moreover, the image formation principle on which PICsIT works is that of coded imaging in which the entire detection plane contributes to each decoded sky pixel. For these two main reasons, the monitoring, and possible correction, of the spatial and temporal non-uniformity of pixel performances, especially in terms of gain and energy resolution, is of paramount importance. The IBIS on-board 22 Na calibration source allows the calibration of each pixel at an accuracy of <0.5% by integrating the data from a few revolutions at constant temperature. The two calibration lines, at 511 and 1275 keV, allow also the measurement and monitoring of the PICsIT energy resolution which proves to be very stable at ∼ 19% and ∼ 9% (FWHM) respectively, and consistent with the values expected analytical predictions checked against pre-launch tests. (authors)

Calibration of AXAF Mirrors Using Synchrotron Radiation

Science.gov (United States)

Graessle, D. E.; Fitch, J.; Harris, B.; Hsieh, P.; Nguyen, D.; Hughes, J.; Schwartz, D.; Blake, R.

1995-12-01

Over the past five years, the SAO AXAF Mission Support Team has been developing methods and systems to provide a tunable, narrow-energy-bandwidth calibration of the reflecting efficiency of the AXAF High Resolution Mirror Assembly. A group of synchrotron beamlines at the National Synchrotron Light Source was selected for this calibration. Measurements and analysis are now available for the 2-12 keV energy range. An X-ray beam with energy purity E/Delta E ~ 5000 has been used to calibrate several witness flats which were coated simultaneously with elements of the flight mirror. In the iridium-edge range, (2010-3200 eV), these may be the first measurements ever to be reported. Optical constants for the iridium have been derived from a fit of reflectance versus grazing angle to a Fresnel equation model for the 2-12 keV energy range. The eight AXAF HRMA elements are being coated individually; however reflectance results are quite consistent from coating run to coating run for the first few pieces. The measurement precision is approximately 0.2%-0.4%. Residuals of the fit are nearly always within 1.0% of the data values, in the angle ranges of interest to AXAF.

Calibration curves for quantifying praseodymium by UV-VIS; Curvas de calibracion para cuantificar praseodimio por UV-VIS

Energy Technology Data Exchange (ETDEWEB)

Gonzalez M, R.; Lopez G, H.; Rojas H, A. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico)]. e-mail: robertssd1199@yahoo.com.mx

2007-07-01

The UV-Vis spectroscopic technique was used to determine the absorption bands depending on the concentration from the praseodymium solutions at pH3. Those more appropriate were in the wavelength of 215 nm, for concentrations of 0.0001-0.026 M, of 481nm, 468 nm and 443 nm, for concentrations of 0.026-0.325 M, and of 589 nm, for concentrations of 0.026-0.65 M of the praseodymium. To these wavelengths the calibration curves were determined, which presented correlation coefficients between 0.9976 and 0.9999 except of the absorption of 589 nm that gave R{sup 2} = 0.9014. (Author)

Development of a low background test facility for the SPICA-SAFARI on-ground calibration

Science.gov (United States)

Dieleman, P.; Laauwen, W. M.; Ferrari, L.; Ferlet, M.; Vandenbussche, B.; Meinsma, L.; Huisman, R.

2012-09-01

SAFARI is a far-infrared camera to be launched in 2021 onboard the SPICA satellite. SAFARI offers imaging spectroscopy and imaging photometry in the wavelength range of 34 to 210 μm with detector NEP of 2•10-19 W/√Hz. A cryogenic test facility for SAFARI on-ground calibration and characterization is being developed. The main design driver is the required low background of a few attoWatts per pixel. This prohibits optical access to room temperature and hence all test equipment needs to be inside the cryostat at 4.5K. The instrument parameters to be verified are interfaces with the SPICA satellite, sensitivity, alignment, image quality, spectral response, frequency calibration, and point spread function. The instrument sensitivity is calibrated by a calibration source providing a spatially homogeneous signal at the attoWatt level. This low light intensity is achieved by geometrical dilution of a 150K source to an integrating sphere. The beam quality and point spread function is measured by a pinhole/mask plate wheel, back-illuminated by a second integrating sphere. This sphere is fed by a stable wide-band source, providing spectral lines via a cryogenic etalon.

Beer Law Constants and Vapor Pressures of HgI2 over HgI2(s,l)

Science.gov (United States)

Su, Ching-Hua; Zhu, Shen; Ramachandran, N.; Burger, A.

2002-01-01

Optical absorption spectra of the vapor phase over HgI2(s,l) were measured at sample temperatures between 349 and 610 K for wavelengths between 200 and 600 nm. The spectra show the samples sublimed congruently into HGI2 without any observed Hg or I2 absorption spectra. The Beer's Law constants for 15 wavelengths between 200 and 440 nm were derived. From these constants the vapor pressure of HgI2, P, was found to be a function of temperature for the liquid and the solid beta-phases: ln P(atm) = -7700/T(K) + 12.462 (liquid phase) and ln P(atm) = -10150/T(K) + 17.026 (beta-phase). The expressions match the enthalpies of vaporization and sublimation of 15.30 and 20.17 kcal/mole respectively, for the liquid and the beta-phase HgI2. The difference in the enthalpies gives an enthalpy of fusion of 4.87 kcal/mole, and the intersection of the two expressions gives a melting point of 537 K.

Drift-insensitive distributed calibration of probe microscope scanner in nanometer range: Virtual mode

Science.gov (United States)

Lapshin, Rostislav V.

2016-08-01

A method of distributed calibration of a probe microscope scanner is suggested. The main idea consists in a search for a net of local calibration coefficients (LCCs) in the process of automatic measurement of a standard surface, whereby each point of the movement space of the scanner can be characterized by a unique set of scale factors. Feature-oriented scanning (FOS) methodology is used as a basis for implementation of the distributed calibration permitting to exclude in situ the negative influence of thermal drift, creep and hysteresis on the obtained results. Possessing the calibration database enables correcting in one procedure all the spatial systematic distortions caused by nonlinearity, nonorthogonality and spurious crosstalk couplings of the microscope scanner piezomanipulators. To provide high precision of spatial measurements in nanometer range, the calibration is carried out using natural standards - constants of crystal lattice. One of the useful modes of the developed calibration method is a virtual mode. In the virtual mode, instead of measurement of a real surface of the standard, the calibration program makes a surface image ;measurement; of the standard, which was obtained earlier using conventional raster scanning. The application of the virtual mode permits simulation of the calibration process and detail analysis of raster distortions occurring in both conventional and counter surface scanning. Moreover, the mode allows to estimate the thermal drift and the creep velocities acting while surface scanning. Virtual calibration makes possible automatic characterization of a surface by the method of scanning probe microscopy (SPM).

SMAP RADAR Calibration and Validation

Science.gov (United States)

West, R. D.; Jaruwatanadilok, S.; Chaubel, M. J.; Spencer, M.; Chan, S. F.; Chen, C. W.; Fore, A.

2015-12-01

The Soil Moisture Active Passive (SMAP) mission launched on Jan 31, 2015. The mission employs L-band radar and radiometer measurements to estimate soil moisture with 4% volumetric accuracy at a resolution of 10 km, and freeze-thaw state at a resolution of 1-3 km. Immediately following launch, there was a three month instrument checkout period, followed by six months of level 1 (L1) calibration and validation. In this presentation, we will discuss the calibration and validation activities and results for the L1 radar data. Early SMAP radar data were used to check commanded timing parameters, and to work out issues in the low- and high-resolution radar processors. From April 3-13 the radar collected receive only mode data to conduct a survey of RFI sources. Analysis of the RFI environment led to a preferred operating frequency. The RFI survey data were also used to validate noise subtraction and scaling operations in the radar processors. Normal radar operations resumed on April 13. All radar data were examined closely for image quality and calibration issues which led to improvements in the radar data products for the beta release at the end of July. Radar data were used to determine and correct for small biases in the reported spacecraft attitude. Geo-location was validated against coastline positions and the known positions of corner reflectors. Residual errors at the time of the beta release are about 350 m. Intra-swath biases in the high-resolution backscatter images are reduced to less than 0.3 dB for all polarizations. Radiometric cross-calibration with Aquarius was performed using areas of the Amazon rain forest. Cross-calibration was also examined using ocean data from the low-resolution processor and comparing with the Aquarius wind model function. Using all a-priori calibration constants provided good results with co-polarized measurements matching to better than 1 dB, and cross-polarized measurements matching to about 1 dB in the beta release. During the

Is X-ray emissivity constant on magnetic flux surfaces?

International Nuclear Information System (INIS)

Granetz, R.S.; Borras, M.C.

1997-01-01

Knowledge of the elongations and shifts of internal magnetic flux surfaces can be used to determine the q profile in elongated tokamak plasmas. X-ray tomography is thought to be a reasonable technique for independently measuring internal flux surface shapes, because it is widely believed that X-ray emissivity should be constant on a magnetic flux surface. In the Alcator C-Mod tokamak, the X-ray tomography diagnostic system consists of four arrays of 38 chords each. A comparison of reconstructed X-ray contours with magnetic flux surfaces shows a small but consistent discrepancy in the radial profile of elongation. Numerous computational tests have been performed to verify these findings, including tests of the sensitivity to calibration and viewing geometry errors, the accuracy of the tomography reconstruction algorithms, and other subtler effects. We conclude that the discrepancy between the X-ray contours and the magnetic flux surfaces is real, leading to the conclusion that X-ray emissivity is not exactly constant on a flux surface. (orig.)

Astrometric Calibration and Performance of the Dark Energy Camera

Energy Technology Data Exchange (ETDEWEB)

Bernstein, G. M.; Armstrong, R.; Plazas, A. A.; Walker, A. R.; Abbott, T. M. C.; Allam, S.; Bechtol, K.; Benoit-Lévy, A.; Brooks, D.; Burke, D. L.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Cunha, C. E.; Costa, L. N. da; DePoy, D. L.; Desai, S.; Diehl, H. T.; Eifler, T. F.; Fernandez, E.; Fosalba, P.; Frieman, J.; García-Bellido, J.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; Gschwend, J.; Gutierrez, G.; Honscheid, K.; James, D. J.; Kent, S.; Krause, E.; Kuehn, K.; Kuropatkin, N.; Li, T. S.; Maia, M. A. G.; March, M.; Marshall, J. L.; Menanteau, F.; Miquel, R.; Ogando, R. L. C.; Reil, K.; Roodman, A.; Rykoff, E. S.; Sanchez, E.; Scarpine, V.; Schindler, R.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, M.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.

2017-05-30

We characterize the variation in photometric response of the Dark Energy Camera (DECam) across its 520~Mpix science array during 4 years of operation. These variations are measured using high signal-to-noise aperture photometry of $>10^7$ stellar images in thousands of exposures of a few selected fields, with the telescope dithered to move the sources around the array. A calibration procedure based on these results brings the RMS variation in aperture magnitudes of bright stars on cloudless nights down to 2--3 mmag, with <1 mmag of correlated photometric errors for stars separated by $\\ge20$". On cloudless nights, any departures of the exposure zeropoints from a secant airmass law exceeding >1 mmag are plausibly attributable to spatial/temporal variations in aperture corrections. These variations can be inferred and corrected by measuring the fraction of stellar light in an annulus between 6" and 8" diameter. Key elements of this calibration include: correction of amplifier nonlinearities; distinguishing pixel-area variations and stray light from quantum-efficiency variations in the flat fields; field-dependent color corrections; and the use of an aperture-correction proxy. The DECam response pattern across the 2-degree field drifts over months by up to $\\pm7$ mmag, in a nearly-wavelength-independent low-order pattern. We find no fundamental barriers to pushing global photometric calibrations toward mmag accuracy.

Primary calibration of TXRF in comparison with the standard droplet procedure

International Nuclear Information System (INIS)

Dobler, M.; Reus, U.; Knoth, J.; Schwenke, H.

2000-01-01

For the determination of contamination on wafer surfaces with total reflection x-ray fluorescence spectrometry (TXRF) normally external 1 ng Ni droplet standards were used for calibration. This method is based on several assumptions about the properties of the standard droplet which are strongly affected by the preparation of the samples. In this paper a study is resented which compares the external droplet method with a calibration procedure using the fundamental physical background of total reflection x-ray fluorescence spectrometry and the properties of Ni bulk material. The particular features of the two methods will be discussed and the obtained results compared to each other. It is demonstrated in this study that the calibration with Ni bulk material is a primary method which offers several advantages compared to the calibration based on droplet standards. These advantages are unique and enable a more reliable and reproducible quantification of contamination on wafer surfaces. This is caused by the fact that the method is standardless and only based on fundamental parameters and natural constants. It is also demonstrated that effects which could be caused by especial features of the measured samples (particle or film, e.g.) or by the degradation of the calibration sample could be excluded. (author)

Improved Regression Analysis of Temperature-Dependent Strain-Gage Balance Calibration Data

Science.gov (United States)

Ulbrich, N.

2015-01-01

An improved approach is discussed that may be used to directly include first and second order temperature effects in the load prediction algorithm of a wind tunnel strain-gage balance. The improved approach was designed for the Iterative Method that fits strain-gage outputs as a function of calibration loads and uses a load iteration scheme during the wind tunnel test to predict loads from measured gage outputs. The improved approach assumes that the strain-gage balance is at a constant uniform temperature when it is calibrated and used. First, the method introduces a new independent variable for the regression analysis of the balance calibration data. The new variable is designed as the difference between the uniform temperature of the balance and a global reference temperature. This reference temperature should be the primary calibration temperature of the balance so that, if needed, a tare load iteration can be performed. Then, two temperature{dependent terms are included in the regression models of the gage outputs. They are the temperature difference itself and the square of the temperature difference. Simulated temperature{dependent data obtained from Triumph Aerospace's 2013 calibration of NASA's ARC-30K five component semi{span balance is used to illustrate the application of the improved approach.

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

Science.gov (United States)

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.

Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations for solvent-based carbon capture. Part 2: Chemical absorption across a wetted wall column: Original Research Article: Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations

Energy Technology Data Exchange (ETDEWEB)

Wang, Chao [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Physical and Computational Sciences Directorate; Xu, Zhijie [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Physical and Computational Sciences Directorate; Lai, Kevin [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Physical and Computational Sciences Directorate; Whyatt, Greg [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Energy and Environment Directorate; Marcy, Peter W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sun, Xin [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Energy and Transportation Science Division

2017-10-24

Part 1 of this paper presents a numerical model for non-reactive physical mass transfer across a wetted wall column (WWC). In Part 2, we improved the existing computational fluid dynamics (CFD) model to simulate chemical absorption occurring in a WWC as a bench-scale study of solvent-based carbon dioxide (CO₂) capture. In this study, to generate data for WWC model validation, CO₂ mass transfer across a monoethanolamine (MEA) solvent was first measured on a WWC experimental apparatus. The numerical model developed in this work can account for both chemical absorption and desorption of CO₂ in MEA. In addition, the overall mass transfer coefficient predicted using traditional/empirical correlations is conducted and compared with CFD prediction results for both steady and wavy falling films. A Bayesian statistical calibration algorithm is adopted to calibrate the reaction rate constants in chemical absorption/desorption of CO₂ across a falling film of MEA. The posterior distributions of the two transport properties, i.e., Henry's constant and gas diffusivity in the non-reacting nitrous oxide (N₂O)/MEA system obtained from Part 1 of this study, serves as priors for the calibration of CO₂ reaction rate constants after using the N₂O/CO₂ analogy method. Finally, the calibrated model can be used to predict the CO₂ mass transfer in a WWC for a wider range of operating conditions.

High-accuracy measurements of snow Bidirectional Reflectance Distribution Function at visible and NIR wavelengths – comparison with modelling results

Directory of Open Access Journals (Sweden)

M. Dumont

2010-03-01

Full Text Available High-accuracy measurements of snow Bidirectional Reflectance Distribution Function (BRDF were performed for four natural snow samples with a spectrogonio-radiometer in the 500–2600 nm wavelength range. These measurements are one of the first sets of direct snow BRDF values over a wide range of lighting and viewing geometry. They were compared to BRDF calculated with two optical models. Variations of the snow anisotropy factor with lighting geometry, wavelength and snow physical properties were investigated. Results show that at wavelengths with small penetration depth, scattering mainly occurs in the very top layers and the anisotropy factor is controlled by the phase function. In this condition, forward scattering peak or double scattering peak is observed. In contrast at shorter wavelengths, the penetration of the radiation is much deeper and the number of scattering events increases. The anisotropy factor is thus nearly constant and decreases at grazing observation angles. The whole dataset is available on demand from the corresponding author.

Flux density measurements of radio sources at 2.14 millimeter wavelength

International Nuclear Information System (INIS)

Cogdell, J.R.; Davis, J.H.; Ulrich, B.T.; Wills, B.J.

1975-01-01

Flux densities of galactic and extragalactic sources, and planetary temperatures, have been measured at 2.14 mm wavelength (140 GHz). Results are presented for OJ 287; the galactic sources DR 21, W3, and Orion A; the extragalactic sources PKS 0106plus-or-minus01, 3C 84, 3C 120, BL Lac, 3C 216, 3C 273, 3C 279, and NGC 4151; and the Sun, Venus, Mars, and Jupiter. Also presented is the first measurement of the 2.14-mm temperature of Uranus. The spectra of some of these sources are discussed. The flux density scale was calibrated absolutely. The measurements were made with a new continuum receiver on the 4.88-m radio telescope of The University of Texas

Detector calibration measurements in CRESST

Energy Technology Data Exchange (ETDEWEB)

Westphal, W. [Technische Universitaet Muenchen, Physik Department E15, James-Franck-Strasse, D-85748 Garching (Germany)]. E-mail: westphal@ph.tum.de; Coppi, C. [Technische Universitaet Muenchen, Physik Department E15, James-Franck-Strasse, D-85748 Garching (Germany); Feilitzsch, F. von [Technische Universitaet Muenchen, Physik Department E15, James-Franck-Strasse, D-85748 Garching (Germany); Isaila, C. [Technische Universitaet Muenchen, Physik Department E15, James-Franck-Strasse, D-85748 Garching (Germany); Jagemann, T. [Eberhard Karls Universitaet Tuebingen, Physikalisches Institut I, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany); Jochum, J. [Eberhard Karls Universitaet Tuebingen, Physikalisches Institut I, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany); Koenig, J. [Technische Universitaet Muenchen, Physik Department E15, James-Franck-Strasse, D-85748 Garching (Germany); Lachenmaier, T. [Technische Universitaet Muenchen, Physik Department E15, James-Franck-Strasse, D-85748 Garching (Germany); Lanfranchi, J.-C. [Technische Universitaet Muenchen, Physik Department E15, James-Franck-Strasse, D-85748 Garching (Germany); Potzel, W. [Technische Universitaet Muenchen, Physik Department E15, James-Franck-Strasse, D-85748 Garching (Germany); Rau, W. [Technische Universitaet Muenchen, Physik Department E15, James-Franck-Strasse, D-85748 Garching (Germany); Stark, M. [Technische Universitaet Muenchen, Physik Department E15, James-Franck-Strasse, D-85748 Garching (Germany); Wernicke, D. [Technische Universitaet Muenchen, Physik Department E15, James-Franck-Strasse, D-85748 Garching (Germany); VeriCold Technologies GmbH, Bahnhofstrasse 21, D-85737 Ismaning (Germany)

2006-04-15

The CRESST dark matter experiment uses the simultaneous measurement of the scintillation light and the heat signal of a CaWO{sub 4} crystal to discriminate between background electron recoil and nuclear recoil events. At the Technical University of Munich calibration measurements have been performed to characterize the detectors. These measurements include the determination of the light output and scintillation time constants of CaWO{sub 4} at temperatures below 50 mK. The setup used in these measurements consist of a CaWO{sub 4} crystal, which is mounted in a reflective housing together with a silicon light detector carrying an Ir/Au transition edge sensor (TES) evaporated directly onto it.

Calibration of a neutron log in partially saturated media. Part II. Error analysis

International Nuclear Information System (INIS)

Hearst, J.R.; Kasameyer, P.W.; Dreiling, L.A.

1981-01-01

Four sources or error (uncertainty) are studied in water content obtained from neutron logs calibrated in partially saturated media for holes up to 3 m. For this calibration a special facility was built and an algorithm for a commercial epithermal neutron log was developed that obtains water content from count rate, bulk density, and gap between the neutron sonde and the borehole wall. The algorithm contained errors due to the calibration and lack of fit, while the field measurements included uncertainties in the count rate (caused by statistics and a short time constant), gap, and density. There can be inhomogeneity in the material surrounding the borehole. Under normal field conditions the hole-size-corrected water content obtained from such neutron logs can have an uncertainty as large as 15% of its value

Elongational flow of polymer melts at constant strain rate, constant stress and constant force

Science.gov (United States)

Wagner, Manfred H.; Rolón-Garrido, Víctor H.

2013-04-01

Characterization of polymer melts in elongational flow is typically performed at constant elongational rate or rarely at constant tensile stress conditions. One of the disadvantages of these deformation modes is that they are hampered by the onset of "necking" instabilities according to the Considère criterion. Experiments at constant tensile force have been performed even more rarely, in spite of the fact that this deformation mode is free from necking instabilities and is of considerable industrial relevance as it is the correct analogue of steady fiber spinning. It is the objective of the present contribution to present for the first time a full experimental characterization of a long-chain branched polyethylene melt in elongational flow. Experiments were performed at constant elongation rate, constant tensile stress and constant tensile force by use of a Sentmanat Extensional Rheometer (SER) in combination with an Anton Paar MCR301 rotational rheometer. The accessible experimental window and experimental limitations are discussed. The experimental data are modelled by using the Wagner I model. Predictions of the steady-start elongational viscosity in constant strain rate and creep experiments are found to be identical, albeit only by extrapolation of the experimental data to Hencky strains of the order of 6. For constant stress experiments, a minimum in the strain rate and a corresponding maximum in the elongational viscosity is found at a Hencky strain of the order of 3, which, although larger than the steady-state value, follows roughly the general trend of the steady-state elongational viscosity. The constitutive analysis also reveals that constant tensile force experiments indicate a larger strain hardening potential than seen in constant elongation rate or constant tensile stress experiments. This may be indicative of the effect of necking under constant elongation rate or constant tensile stress conditions according to the Considère criterion.

Genetic algorithm-based wavelength selection in multicomponent spectrophotometric determination by PLS: Application on sulfamethoxazole and trimethoprim mixture in bovine milk

Directory of Open Access Journals (Sweden)

Givianrad Hadi Mohammad

2013-01-01

Full Text Available The simultaneous determination of sulfamethoxazole (SMX and trimethoprim (TMP mixtures in bovine milk by spectrophotometric method is a difficult problem in analytical chemistry, due to spectral interferences. By means of multivariate calibration methods, such as partial least square (PLS regression, it is possible to obtain a model adjusted to the concentration values of the mixtures used in the calibration range. Genetic algorithm (GA is a suitable method for selecting wavelengths for PLS calibration of mixtures with almost identical spectra without loss of prediction capacity using the spectrophotometric method. In this study, the calibration model based on absorption spectra in the 200-400 nm range for 25 different mixtures of SMX and TMP Calibration matrices were formed form samples containing 0.25-20 and 0.3-21 μg mL-1 for SMX and TMP, at pH=10, respectively. The root mean squared error of deviation (RMSED for SMX and TMP with PLS and genetic algorithm partial least square (GAPLS were 0.242, 0.066 μgmL-1 and 0.074, 0.027 μg mL-1, respectively. This procedure was allowed the simultaneous determination of SMX and TMP in synthetic and real samples and good reliability of the determination was proved.

Calibration Transfer Between a Bench Scanning and a Submersible Diode Array Spectrophotometer for In Situ Wastewater Quality Monitoring in Sewer Systems.

Science.gov (United States)

Brito, Rita S; Pinheiro, Helena M; Ferreira, Filipa; Matos, José S; Pinheiro, Alexandre; Lourenço, Nídia D

2016-03-01

Online monitoring programs based on spectroscopy have a high application potential for the detection of hazardous wastewater discharges in sewer systems. Wastewater hydraulics poses a challenge for in situ spectroscopy, especially when the system includes storm water connections leading to rapid changes in water depth, velocity, and in the water quality matrix. Thus, there is a need to optimize and fix the location of in situ instruments, limiting their availability for calibration. In this context, the development of calibration models on bench spectrophotometers to estimate wastewater quality parameters from spectra acquired with in situ instruments could be very useful. However, spectra contain information not only from the samples, but also from the spectrophotometer generally invalidating this approach. The use of calibration transfer methods is a promising solution to this problem. In this study, calibration models were developed using interval partial least squares (iPLS), for the estimation of total suspended solids (TSS) and chemical oxygen demand (COD) in sewage from Ultraviolet-visible spectra acquired in a bench scanning spectrophotometer. The feasibility of calibration transfer to a submersible, diode array equipment, to be subsequently operated in situ, was assessed using three procedures: slope and bias correction (SBC); single wavelength standardization (SWS) on mean spectra; and local centering (LC). The results showed that SBC was the most adequate for the available data, adding insignificant error to the base model estimates. Single wavelength standardization was a close second best, potentially more robust, and independent of the base iPLS model. Local centering was shown to be inadequate for the samples and instruments used. © The Author(s) 2016.

Radioligand assays - methods and applications. IV. Uniform regression of hyperbolic and linear radioimmunoassay calibration curves

Energy Technology Data Exchange (ETDEWEB)

Keilacker, H; Becker, G; Ziegler, M; Gottschling, H D [Zentralinstitut fuer Diabetes, Karlsburg (German Democratic Republic)

1980-10-01

In order to handle all types of radioimmunoassay (RIA) calibration curves obtained in the authors' laboratory in the same way, they tried to find a non-linear expression for their regression which allows calibration curves with different degrees of curvature to be fitted. Considering the two boundary cases of the incubation protocol they derived a hyperbolic inverse regression function: x = a/sub 1/y + a/sub 0/ + asub(-1)y/sup -1/, where x is the total concentration of antigen, asub(i) are constants, and y is the specifically bound radioactivity. An RIA evaluation procedure based on this function is described providing a fitted inverse RIA calibration curve and some statistical quality parameters. The latter are of an order which is normal for RIA systems. There is an excellent agreement between fitted and experimentally obtained calibration curves having a different degree of curvature.

LHCb full-detector real-time alignment and calibration: latest developments and perspective

CERN Multimedia

Dziurda, Agnieszka

2018-01-01

A key ingredient of the data taking strategy used by the LHCb experiment at CERN in Run 2 is the novel real-time detector alignment and calibration. Data collected at the start of the fill are processed within minutes and used to update the alignment, while the calibration constants are evaluated hourly. This is one of the key elements which allow the reconstruction quality of the software trigger in Run-II to be as good as the offline quality of Run 1. The most recent developments of the real-time alignment and calibration paradigm enable the fully automated updates of the RICH detectors' mirror alignment and a novel calibration of the calorimeter systems. Both evolutions improve the particle identification performance stability resulting in higher purity selections. The latter leads also to an improvement in the energy measurement of neutral particles, resulting in a 15% better mass resolution of radiative b-hadron decays. A large variety of improvements has been explored for the last year of Run 2 data tak...

Predictive sensor based x-ray calibration using a physical model

International Nuclear Information System (INIS)

Fuente, Matias de la; Lutz, Peter; Wirtz, Dieter C.; Radermacher, Klaus

2007-01-01

Many computer assisted surgery systems are based on intraoperative x-ray images. To achieve reliable and accurate results these images have to be calibrated concerning geometric distortions, which can be distinguished between constant distortions and distortions caused by magnetic fields. Instead of using an intraoperative calibration phantom that has to be visible within each image resulting in overlaying markers, the presented approach directly takes advantage of the physical background of the distortions. Based on a computed physical model of an image intensifier and a magnetic field sensor, an online compensation of distortions can be achieved without the need of an intraoperative calibration phantom. The model has to be adapted once to each specific image intensifier through calibration, which is based on an optimization algorithm systematically altering the physical model parameters, until a minimal error is reached. Once calibrated, the model is able to predict the distortions caused by the measured magnetic field vector and build an appropriate dewarping function. The time needed for model calibration is not yet optimized and takes up to 4 h on a 3 GHz CPU. In contrast, the time needed for distortion correction is less than 1 s and therefore absolutely acceptable for intraoperative use. First evaluations showed that by using the model based dewarping algorithm the distortions of an XRII with a 21 cm FOV could be significantly reduced. The model was able to predict and compensate distortions by approximately 80% to a remaining error of 0.45 mm (max) (0.19 mm rms)

In-Flight Calibration of the MMS Fluxgate Magnetometers

Science.gov (United States)

Bromund, K. R.; Plaschke, F.; Strangeway, R. J.; Anderson, B. J.; Huang, B. G.; Magnes, W.; Fischer, D.; Nakamura, R.; Leinweber, H. K.; Russell, C. T.;

Read-out and calibration of a tile calorimeter for ATLAS

International Nuclear Information System (INIS)

Tardell, S.

1997-06-01

The read-out and calibration of scintillating tiles hadronic calorimeter for ATLAS is discussed. Tests with prototypes of FERMI, a system of read-out electronics based on a dynamic range compressor reducing the dynamic range from 16 to 10 bits and a 40 MHz 10 bits sampling ADC, are presented. In comparison with a standard charge integrating read-out improvements in the resolution of 1% in the constant term are obtained

Wavelength dependent pH optical sensor using the layer-by-layer technique

OpenAIRE

Raoufi, N.; Surre, F.; Sun, T.; Rajarajan, M.; Grattan, K. T. V.

2012-01-01

In this work, the design and characteristics of a wavelength-dependent pH optical sensor have been studied. To create the sensor itself, brilliant yellow (BY) as a pH indicator and poly (allylamine hydrochloride) [PAH] as a cross-linker have been deposited on the end of a bare silica core of an optical fibre by use of a ‘layer-by-layer’ technique. In the experiments carried out to characterize the sensor, it was observed that the value of pKa (the dissociation constant) of the thin film is de...

WAVELENGTH SELECTION OF HYPERSPECTRAL LIDAR BASED ON FEATURE WEIGHTING FOR ESTIMATION OF LEAF NITROGEN CONTENT IN RICE

Directory of Open Access Journals (Sweden)

L. Du

2016-06-01

Full Text Available Hyperspectral LiDAR (HSL is a novel tool in the field of active remote sensing, which has been widely used in many domains because of its advantageous ability of spectrum-gained. Especially in the precise monitoring of nitrogen in green plants, the HSL plays a dispensable role. The exiting HSL system used for nitrogen status monitoring has a multi-channel detector, which can improve the spectral resolution and receiving range, but maybe result in data redundancy, difficulty in system integration and high cost as well. Thus, it is necessary and urgent to pick out the nitrogen-sensitive feature wavelengths among the spectral range. The present study, aiming at solving this problem, assigns a feature weighting to each centre wavelength of HSL system by using matrix coefficient analysis and divergence threshold. The feature weighting is a criterion to amend the centre wavelength of the detector to accommodate different purpose, especially the estimation of leaf nitrogen content (LNC in rice. By this way, the wavelengths high-correlated to the LNC can be ranked in a descending order, which are used to estimate rice LNC sequentially. In this paper, a HSL system which works based on a wide spectrum emission and a 32-channel detector is conducted to collect the reflectance spectra of rice leaf. These spectra collected by HSL cover a range of 538 nm – 910 nm with a resolution of 12 nm. These 32 wavelengths are strong absorbed by chlorophyll in green plant among this range. The relationship between the rice LNC and reflectance-based spectra is modeled using partial least squares (PLS and support vector machines (SVMs based on calibration and validation datasets respectively. The results indicate that I wavelength selection method of HSL based on feature weighting is effective to choose the nitrogen-sensitive wavelengths, which can also be co-adapted with the hardware of HSL system friendly. II The chosen wavelength has a high correlation with rice LNC

Calibration and performance test of the Very-Front-End electronics for the CMS electromagnetic calorimeter

International Nuclear Information System (INIS)

Blaha, J.

2008-05-01

A Very-Front-End (VFE) card is an important part of the on-detector read-out electronics of the CMS (Compact Muon Solenoid) electromagnetic calorimeter that is made of ∼ 76.000 radiation hard scintillating crystals PbWO 4 and operates on the Large Hadron Collider (LHC) at CERN. Almost 16.000 VFE cards that shape, amplify and digitize incoming signals from photodetectors generated by interacting particles. Since any maintenance of any part of the calorimeter is not possible during the 10-year lifetime of the experiment, the extensive screening program was employed throughout the whole manufacture process. As a part of readout electronics quality assurance program, the systems for burn-in and precise calibration of the VFE boards were developed and successfully used at IPN Lyon. In addition to functionality tests, all relevant electrical properties of each card were measured and analyzed in detail to obtain their full characterization and to build a database with all required parameters which will serve for the initial calibration of the whole calorimeter. In order to evaluate the calorimeter performance and also to deliver the most precise calibration constants, several fully equipped super-modules were extensively studied and calibrated during the test beam campaigns at CERN. As an important part of these tests, accurate studies of the electronics noise and relative gains, which are needed for measurement in high energy range, were carried out to optimize amplitude reconstruction procedure and thus improve the precision of the calorimeter energy determination. The heart of the thesis consists of the calibration of all VFE boards, including optimization of the laboratory calibration system and precise analysis of measured values to delivered desired calibration constants. The second half of the thesis is focused on the accurate evaluation and optimization of the read-out electronics in real data taking conditions. The results obtained in the laboratory at IPN Lyon

Broadband multi-wavelength Brillouin lasers with an operating wavelength range of 1500–1600 nm generated by four-wave mixing in a dual wavelength Brillouin fiber laser cavity

Science.gov (United States)

Li, Q.; Jia, Z. X.; Weng, H. Z.; Li, Z. R.; Yang, Y. D.; Xiao, J. L.; Chen, S. W.; Huang, Y. Z.; Qin, W. P.; Qin, G. S.

2018-05-01

We demonstrate broadband multi-wavelength Brillouin lasers with an operating wavelength range of 1500–1600 nm and a frequency separation of ~9.28 GHz generated by four-wave mixing in a dual wavelength Brillouin fiber laser cavity. By using one continuous-wave laser as the pump source, multi-wavelength Brillouin lasers with an operating wavelength range of 1554–1574 nm were generated via cascaded Brillouin scattering and four-wave mixing. Interestingly, when pumped by two continuous-wave lasers with an appropriate frequency separation, the operating wavelength range of the multi-wavelength Brillouin lasers was increased to 1500–1600 nm due to cavity-enhanced cascaded four-wave mixing among the frequency components generated by two pump lasers in the dual wavelength Brillouin laser cavity.

Control over the resonance wavelength of fibre Bragg gratings using resistive coatings based on single-wall carbon nanotubes

Science.gov (United States)

Gladush, Yu. G.; Medvedkov, O. I.; Vasil'ev, S. A.; Kopylova, D. S.; Yakovlev, V. Ya.; Nasibulin, A. G.

2016-10-01

We demonstrate that a thin resistive coating based on single-wall carbon nanotubes applied to the lateral surface of an optical fibre allows it to be uniformly heated up to a temperature of ∼ 400 \\circ{\\text{C}} without damage to the coating. Using a fibre Bragg grating (FBG) as an example, we assess the efficiency of resonance wavelength thermal tuning and examine frequency characteristics that can be achieved using such coating. In particular, we show that the resonance wavelength of the FBG can be tuned over 3.2 {\\text{nm}} with an efficiency of 8.7 {\\text{nm}} {\\text{W}}-1 and time constant of ∼ 0.4 {\\text{s}}.

CALIBRATION PROCEDURES ON OBLIQUE CAMERA SETUPS

Directory of Open Access Journals (Sweden)

G. Kemper

2016-06-01

step with the help of the nadir camera and the GPS/IMU data, an initial orientation correction and radial correction were calculated. With this approach, the whole project was calculated and calibrated in one step. During the iteration process the radial and tangential parameters were switched on individually for the camera heads and after that the camera constants and principal point positions were checked and finally calibrated. Besides that, the bore side calibration can be performed either on basis of the nadir camera and their offsets, or independently for each camera without correlation to the others. This must be performed in a complete mission anyway to get stability between the single camera heads. Determining the lever arms of the nodal-points to the IMU centre needs more caution than for a single camera especially due to the strong tilt angle. Prepared all these previous steps, you get a highly accurate sensor that enables a fully automated data extraction with a rapid update of you existing data. Frequently monitoring urban dynamics is then possible in fully 3D environment.

Thermal power calibrations of the IPR-R1 TRIGA reactor by the calorimetric and the heat balance methods

International Nuclear Information System (INIS)

Mesquita, Amir Zacarias; Rezende, Hugo Cesar; Souza, Rose Mary Gomes do Prado

2009-01-01

Since the first nuclear reactor was built, a number of methodological variations have been evolved for the calibration of the reactor thermal power. Power monitoring of reactors is done by means of neutronic instruments, but its calibration is always done by thermal procedures. The purpose of this paper is to present the results of the thermal power calibration carried out on March 5th, 2009 in the IPR-R1 TRIGA reactor. It was used two procedures: the calorimetric and heat balance methods. The calorimetric procedure was done with the reactor operating at a constant power, with primary cooling system switched off. The rate of temperature rise of the water was recorded. The reactor power is calculate as a function of the temperature-rise rate and the system heat capacity constant. The heat balance procedure consists in the steady-state energy balance of the primary cooling loop of the reactor. For this balance, the inlet and outlet temperatures and the water flow in the primary cooling loop were measured. The heat transferred through the primary loop was added to the heat leakage from the reactor pool. The calorimetric method calibration presented a large uncertainty. The main source of error was the determination of the heat content of the system, due to a large uncertainty in the volume of the water in the system and a lack of homogenization of the water temperature. The heat balance calibration in the primary loop is the standard procedure for calibrating the power of the IPR-R1 TRIGA nuclear reactor. (author))

Estimation of optical constants of a bio-thin layer (onion epidermis), using SPR spectroscopy

International Nuclear Information System (INIS)

Rehman, Saif-ur-; Hayashi, Shinji; Sekkat, Zouheir; Mumtaz, Huma; Shaukat, S F

2014-01-01

We estimate the optical constants of a biological thin layer (Allium cepa) by surface plasmon resonance (SPR) spectroscopy. For this study, the fresh inner thin epidermis of an onion bulb was used and stacked directly on gold (Au) and silver (Ag) film surfaces in order to identify the shift in SPR mode of each metal film at an operating wavelength of 632.8 nm. The thickness and dielectric constants of the biological thin layer were determined by matching the experimental SPR curves to theoretical ones. The thickness and roughness of bare Au and Ag thin films were also measured by atomic force microscopy (AFM); the results of which are in good agreement with those obtained through experiment. Due to the high surface roughness of the natural onion epidermis layer, AFM could not measure the exact thickness of an onion epidermis. It is estimated that the value of the real part of the dielectric constant of an onion epidermis is between the dielectric constants of water and air. (paper)

Effective X-ray elastic constant measurement for in situ stress measurement of biaxially strained AA5754-O

International Nuclear Information System (INIS)

Iadicola, Mark A.; Gnäupel-Herold, Thomas H.

2012-01-01

Accurate measurement of stresses by X-ray diffraction requires accurate X-ray elastic constants. Calibration experiments are one method to determine these for a specific material in a specific condition. In this paper, uniaxial tension experiments are used to investigate the variation of these constants after uniaxial and equal-biaxial plastic deformation for an aluminum alloy (AA5754-O) of interest to the automotive industry. These data are critical for accurate measurement of the biaxial mechanical properties of the material using a recent experimental method combining specialized sheet metal forming equipment with portable X-ray diffraction equipment. The measured effective X-ray elastic constants show some minor variation with increased plastic deformation, and this behavior was found to be consistent for both uniaxially and equal-biaxially strained samples. The use of two average values for effective X-ray elastic constants, one in the rolling direction and one transverse to the rolling direction of the sheet material, is shown to be of sufficient accuracy for the combined tests of interest. Comparison of uniaxial data measured using X-ray diffraction and standard methods show good agreement, and biaxial stress–strain results show good repeatability. Additionally, the calibration data show some non-linear behavior, which is analyzed in regards to crystallographic texture and intergranular stress effects. The non-linear behavior is found to be the result of intergranular stresses based on comparison with additional measurements using other X-ray diffraction equipment and neutron diffraction.

Major constituent quantitative determination in uranium alloys by coupled plasma atomic emission spectrometry and X ray fluorescence wavelength dispersive spectrometry

International Nuclear Information System (INIS)

Oliveira, Luis Claudio de; Silva, Adriana Mascarenhas Martins da; Gomide, Ricardo Goncalves; Silva, Ieda de Souza

2013-01-01

A wavelength-dispersive X-ray fluorescence (WD-XRF) spectrometric method for determination of major constituents elements (Zr, Nb, Mo) in Uranium/Zirconium/Niobium and Uranium/Molybdenum alloy samples were developed. The methods use samples taken in the form of chips that were dissolved in hot nitric acid and precipitate particles melted with lithium tetraborate and dissolved in hot nitric acid and finally analyzed as a solution. Studies on the determination by inductively coupled plasma optic emission spectrometry (ICP OES) using matched matrix in calibration curve were developed. The same samples solution were analyzed in both methods. The limits of detection (LOD), linearity of the calibrations curves, recovery study, accuracy and precision of the both techniques were carried out. The results were compared. (author)

Estimating reaction rate constants from a two-step reaction: a comparison between two-way and three-way methods

NARCIS (Netherlands)

Bijlsma, S.; Smilde, A. K.

2000-01-01

In this paper, two different spectral datasets are used in order to estimate reaction rate constants using different algorithms. Dataset 1 consists of short-wavelength near-infrared (SW NIR) spectra taken in time of the two-step epoxidation of 2,5-di-tert-butyl-1,4-benzoquinone using tert-butyl

Another look at volume self-calibration: calibration and self-calibration within a pinhole model of Scheimpflug cameras

International Nuclear Information System (INIS)

Cornic, Philippe; Le Besnerais, Guy; Champagnat, Frédéric; Illoul, Cédric; Cheminet, Adam; Le Sant, Yves; Leclaire, Benjamin

2016-01-01

We address calibration and self-calibration of tomographic PIV experiments within a pinhole model of cameras. A complete and explicit pinhole model of a camera equipped with a 2-tilt angles Scheimpflug adapter is presented. It is then used in a calibration procedure based on a freely moving calibration plate. While the resulting calibrations are accurate enough for Tomo-PIV, we confirm, through a simple experiment, that they are not stable in time, and illustrate how the pinhole framework can be used to provide a quantitative evaluation of geometrical drifts in the setup. We propose an original self-calibration method based on global optimization of the extrinsic parameters of the pinhole model. These methods are successfully applied to the tomographic PIV of an air jet experiment. An unexpected by-product of our work is to show that volume self-calibration induces a change in the world frame coordinates. Provided the calibration drift is small, as generally observed in PIV, the bias on the estimated velocity field is negligible but the absolute location cannot be accurately recovered using standard calibration data. (paper)

Development of theoretical oxygen saturation calibration curve based on optical density ratio and optical simulation approach

Science.gov (United States)

Jumadi, Nur Anida; Beng, Gan Kok; Ali, Mohd Alauddin Mohd; Zahedi, Edmond; Morsin, Marlia

2017-09-01

The implementation of surface-based Monte Carlo simulation technique for oxygen saturation (SaO2) calibration curve estimation is demonstrated in this paper. Generally, the calibration curve is estimated either from the empirical study using animals as the subject of experiment or is derived from mathematical equations. However, the determination of calibration curve using animal is time consuming and requires expertise to conduct the experiment. Alternatively, an optical simulation technique has been used widely in the biomedical optics field due to its capability to exhibit the real tissue behavior. The mathematical relationship between optical density (OD) and optical density ratios (ODR) associated with SaO2 during systole and diastole is used as the basis of obtaining the theoretical calibration curve. The optical properties correspond to systolic and diastolic behaviors were applied to the tissue model to mimic the optical properties of the tissues. Based on the absorbed ray flux at detectors, the OD and ODR were successfully calculated. The simulation results of optical density ratio occurred at every 20 % interval of SaO2 is presented with maximum error of 2.17 % when comparing it with previous numerical simulation technique (MC model). The findings reveal the potential of the proposed method to be used for extended calibration curve study using other wavelength pair.

Suomi-NPP VIIRS Day-Night Band On-Orbit Calibration and Performance

Science.gov (United States)

Chen, Hongda; Xiong, Xiaoxiong; Sun, Chengbo; Chen, Xuexia; Chiang, Kwofu

2017-01-01

The Suomi national polar-orbiting partnership Visible Infrared Imaging Radiometer Suite (VIIRS) instrument has successfully operated since its launch in October 2011. The VIIRS day-night band (DNB) is a panchromatic channel covering wavelengths from 0.5 to 0.9 microns that is capable of observing Earth scenes during both daytime and nighttime at a spatial resolution of 750 m. To cover the large dynamic range, the DNB operates at low-, middle-, and high-gain stages, and it uses an on-board solar diffuser (SD) for its low-gain stage calibration. The SD observations also provide a means to compute the gain ratios of low-to-middle and middle-to-high gain stages. This paper describes the DNB on-orbit calibration methodology used by the VIIRS characterization support team in supporting the NASA Earth science community with consistent VIIRS sensor data records made available by the land science investigator-led processing systems. It provides an assessment and update of the DNB on-orbit performance, including the SD degradation in the DNB spectral range, detector gain and gain ratio trending, and stray-light contamination and its correction. Also presented in this paper are performance validations based on Earth scenes and lunar observations, and comparisons to the calibration methodology used by the operational interface data processing segment.

Constant physics and characteristics of fundamental constant

International Nuclear Information System (INIS)

Tarrach, R.

1998-01-01

We present some evidence which supports a surprising physical interpretation of the fundamental constants. First, we relate two of them through the renormalization group. This leaves as many fundamental constants as base units. Second, we introduce and a dimensional system of units without fundamental constants. Third, and most important, we find, while interpreting the units of the a dimensional system, that is all cases accessible to experimentation the fundamental constants indicate either discretization at small values or boundedness at large values of the corresponding physical quantity. (Author) 12 refs

Calibration voltage test of non invasive meter for radiodiagnostic on equipment of constant potential X-ray

International Nuclear Information System (INIS)

Ramos, Manoel M.O.; Peixoto, J. Guilherme P.; Pereira, Marco A.G.S.

2009-01-01

This work evaluates the utilization of the non invasive voltage meter PTW Diavolt Universal in industrial X ray equipment of constant potential. With the performed measurements, the conclusion is that conclusion is possible, once his use limits are identified

Calibration of TLD cards to beta ray spectra of 32P

International Nuclear Information System (INIS)

Ben-Shachar, B.; German, U.; Naim, E.

1994-01-01

The results of the evaluation of TLD chips are received in nC, and we need to transform these values to mGy, in order to obtain the penetrating and the non-penetrating dose. The calibration factors were determined experimentally by irradiation the TLD chips with an uranium source. Beta rays having other spectra can cause incorrect values when estimating the non-penetrating dose. If the spectrum of the beta source is known, a specific evaluation of the calibration factor can be performed. In this report, the estimation of the calibration factor for a 32 P source is presented. LiF:Ti,Mg TLD cards were irradiated calibrated source of 90 Sr/ 90 Y and 204 Tl and non-calibrated source of 32 P, in order to find the beta correction factor for the spectrum of 32 P. Calculations of the beta correction factor were performed too, by applying the Loevinger equations to the geometry of the TLD chips used in our routine measurements. The calculated values of the beta correction factors are lower than the experimental ones. When comparing the ratios, between the beta factors of 32 P and 90 Sr/ 90 Y received from the experiments and from the calculation, we found them to be constant up to ±5%. (authors) 15 refs, 2 figs, 6 tabs

On the calibration of rectangular atomic force microscope cantilevers modified by particle attachment and lamination

International Nuclear Information System (INIS)

Bowen, James; Zhang, Zhibing; Adams, Michael J; Cheneler, David; Ward, Michael C L; Walliman, Dominic; Arkless, Stuart G

2010-01-01

A simple but effective method for estimating the spring constant of commercially available atomic force microscope (AFM) cantilevers is presented, based on estimating the cantilever thickness from knowledge of its length, width, resonant frequency and the presence or absence of an added mass, such as a colloid probe at the cantilever apex, or a thin film of deposited material. The spring constant of the cantilever can then be estimated using standard equations for cantilever beams. The results are compared to spring constant calibration measurements performed using reference cantilevers. Additionally, the effect of the deposition of Cr and Ti thin films onto rectangular Si cantilevers is investigated

A method for calibration of Soleil-Babinet compensator using a spectrophotometer

Science.gov (United States)

Wang, Jun; Chen, Lei; Li, Bo; Shi, Lili; Luo, Ting

2010-06-01

A method using a spectrophotometer for calibrating Soleil-Babinet compensator is proposed. It is based on the spectroscopic method which utilizes the relation between transmittance and wavelength to obtain retardation. By placing a multiple order half wave plate behind the Soleil-Babinet compensator, zero-order retardation can be measured, which is difficult to accomplish by spectroscopic method. In the experiment, the retardations of the compensator in the range 0- λ are measured. It is demonstrated that the precision of retardation is 0.45 nm at the position 0 and λ while the maximum error is less than 1 nm between the two positions.

Gravimetric method for in vitro calibration of skin hydration measurements.

Science.gov (United States)

Martinsen, Ørjan G; Grimnes, Sverre; Nilsen, Jon K; Tronstad, Christian; Jang, Wooyoung; Kim, Hongsig; Shin, Kunsoo; Naderi, Majid; Thielmann, Frank

2008-02-01

A novel method for in vitro calibration of skin hydration measurements is presented. The method combines gravimetric and electrical measurements and reveals an exponential dependency of measured electrical susceptance to absolute water content in the epidermal stratum corneum. The results also show that absorption of water into the stratum corneum exhibits three different phases with significant differences in absorption time constant. These phases probably correspond to bound, loosely bound, and bulk water.

A Synthesis of Star Calibration Techniques for Ground-Based Narrowband Electron-Multiplying Charge-Coupled Device Imagers Used in Auroral Photometry

Science.gov (United States)

Grubbs, Guy II; Michell, Robert; Samara, Marilia; Hampton, Don; Jahn, Jorg-Micha

2016-01-01

A technique is presented for the periodic and systematic calibration of ground-based optical imagers. It is important to have a common system of units (Rayleighs or photon flux) for cross comparison as well as self-comparison over time. With the advancement in technology, the sensitivity of these imagers has improved so that stars can be used for more precise calibration. Background subtraction, flat fielding, star mapping, and other common techniques are combined in deriving a calibration technique appropriate for a variety of ground-based imager installations. Spectral (4278, 5577, and 8446 A ) ground-based imager data with multiple fields of view (19, 47, and 180 deg) are processed and calibrated using the techniques developed. The calibration techniques applied result in intensity measurements in agreement between different imagers using identical spectral filtering, and the intensity at each wavelength observed is within the expected range of auroral measurements. The application of these star calibration techniques, which convert raw imager counts into units of photon flux, makes it possible to do quantitative photometry. The computed photon fluxes, in units of Rayleighs, can be used for the absolute photometry between instruments or as input parameters for auroral electron transport models.

Study on Relationship between Dielectric Constant and Water Content of Rock-Soil Mixture by Time Domain Reflectometry

Directory of Open Access Journals (Sweden)

Daosheng Ling

2016-01-01

Full Text Available It is important to test water content of rock-soil mixtures efficiently and accurately to ensure both the quality control of compaction and assessment of the geotechnical engineering properties. To overcome time and energy wastage and probe insertion problems when using the traditional calibration method, a TDR coaxial test tube calibration arrangement using an upward infiltration method was designed. This arrangement was then used to study the influence of dry density, pore fluid conductivity, and soil/rock ratio on the relationship between water content and the dielectric constant of rock-soil mixtures. The results show that the empirical calibration equation forms for rock-soil mixtures can be the same as for soil materials. The effect of dry density on the calibration equation has the most significance and the influence of pore fluid conductivity can be ignored. The impact of variation of the soil/rock ratio can be neutralized by considering the effect of dry density in the calibration equation for the same kind of soil and rock. The empirical equations proposed by Zhao et al. show a good accuracy for rock-soil mixtures, indicating that the TDR method can be used to test gravimetric water content conveniently and efficiently without calibration in the field.

Calibration uncertainty

DEFF Research Database (Denmark)

Heydorn, Kaj; Anglov, Thomas

2002-01-01

Methods recommended by the International Standardization Organisation and Eurachem are not satisfactory for the correct estimation of calibration uncertainty. A novel approach is introduced and tested on actual calibration data for the determination of Pb by ICP-AES. The improved calibration...

Design, Performance, and Calibration of the CMS Hadron-Outer Calorimeter

CERN Document Server

Abdullin, Salavat; Acharya, Bannaje Sripathi; Adam, Nadia; Adams, Mark Raymond; Akchurin, Nural; Akgun, Ugur; Albayrak, Elif Asli; Anderson, E Walter; Antchev, Georgy; Arcidy, M; Ayan, S; Aydin, Sezgin; Aziz, Tariq; Baarmand, Marc M; Babich, Kanstantsin; Baden, Drew; Bakirci, Mustafa Numan; Banerjee, Sunanda; Banerjee, Sudeshna; Bard, Robert; Barnes, Virgil E; Bawa, Harinder Singh; Baiatian, G; Bencze, Gyorgy; Beri, Suman Bala; Berntzon, Lisa; Bhatnagar, Vipin; Bhatti, Anwar; Bodek, Arie; Bose, Suvadeep; Bose, Tulika; Budd, Howard; Burchesky, Kyle; Camporesi, Tiziano; Cankocak, Kerem; Carrell, Kenneth Wayne; Cerci, Salim; Chendvankar, Sanjay; Chung, Yeon Sei; Clarida, Warren; Cremaldi, Lucien Marcus; Cushman, Priscilla; Damgov, Jordan; De Barbaro, Pawel; Debbins, Paul; Deliomeroglu, Mehmet; Demianov, A; de Visser, Theo; Deshpande, Pandurang Vishnu; Díaz, Jonathan; Dimitrov, Lubomir; Dugad, Shashikant; Dumanoglu, Isa; Duru, Firdevs; Efthymiopoulos, I; Elias, John E; Elvira, D; Emeliantchik, Igor; Eno, Sarah Catherine; Ershov, Alexander; Erturk, Sefa; Esen, Selda; Eskut, Eda; Fenyvesi, Andras; Fisher, Wade Cameron; Freeman, Jim; Ganguli, Som N; Gaultney, Vanessa; Gamsizkan, Halil; Gavrilov, Vladimir; Genchev, Vladimir; Gleyzer, Sergei V; Golutvin, Igor; Goncharov, Petr; Grassi, Tullio; Green, Dan; Gribushin, Andrey; Grinev, B; Gurtu, Atul; Murat Güler, A; Gülmez, Erhan; Gümüs, K; Haelen, T; Hagopian, Sharon; Hagopian, Vasken; Halyo, Valerie; Hashemi, Majid; Hauptman, John M; Hazen, Eric; Heering, Arjan Hendrix; Heister, Arno; Hunt, Adam; Ilyina, N; Ingram, D; Isiksal, Engin; Jarvis, Chad; Jeong, Chiyoung; Johnson, Kurtis F; Jones, John; Kaftanov, Vitali; Kalagin, Vladimir; Kalinin, Alexey; Kalmani, Suresh Devendrappa; Karmgard, Daniel John; Kaur, Manjit; Kaya, Mithat; Kaya, Ozlem; Kayis-Topaksu, A; Kellogg, Richard G; Khmelnikov, Alexander; Kim, Heejong; Kisselevich, I; Kodolova, Olga; Kohli, Jatinder Mohan; Kolossov, V; Korablev, Andrey; Korneev, Yury; Kosarev, Ivan; Kramer, Laird; Krinitsyn, Alexander; Krishnaswamy, Marthi Ramaswamy; Krokhotin, Andrey; Kryshkin, V; Kuleshov, Sergey; Kumar, Arun; Kunori, Shuichi; Laasanen, Alvin T; Ladygin, Vladimir; Laird, Edward; Landsberg, Greg; Laszlo, Andras; Lawlor, C; Lazic, Dragoslav; Lee, Sang Joon; Levchuk, Leonid; Linn, Stephan; Litvintsev, Dmitri; Lobolo, L; Los, Serguei; Lubinsky, V; Lukanin, Vladimir; Ma, Yousi; Machado, Emanuel; Maity, Manas; Majumder, Gobinda; Mans, Jeremy; Marlow, Daniel; Markowitz, Pete; Martínez, German; Mazumdar, Kajari; Merlo, Jean-Pierre; Mermerkaya, Hamit; Mescheryakov, G; Mestvirishvili, Alexi; Miller, Michael; Möller, A; Mohammadi-Najafabadi, M; Moissenz, P; Mondal, Naba Kumar; Mossolov, Vladimir; Nagaraj, P; Narasimham, Vemuri Syamala; Norbeck, Edwin; Olson, Jonathan; Onel, Yasar; Onengüt, G; Ozkan, Cigdem; Ozkurt, Halil; Ozkorucuklu, Suat; Ozok, Ferhat; Paktinat, S; Pal, Andras; Patil, Mandakini Ravindra; Penzo, Aldo; Petrushanko, Sergey; Petrosian, A; Pikalov, Vladimir; Piperov, Stefan; Podrasky, V; Polatoz, A; Pompos, Arnold; Popescu, Sorina; Posch, C; Pozdnyakov, Andrey; Qian, Weiming; Ralich, Robert; Reddy, L; Reidy, Jim; Rogalev, Evgueni; Roh, Youn; Rohlf, James; Ronzhin, Anatoly; Ruchti, Randy; Ryazanov, Anton; Safronov, Grigory; Sanders, David A; Sanzeni, Christopher; Sarycheva, Ludmila; Satyanarayana, B; Schmidt, Ianos; Sekmen, Sezen; Semenov, Sergey; Senchishin, V; Sergeyev, S; Serin, Meltem; Sever, Ramazan; Singh, B; Singh, Jas Bir; Sirunyan, Albert M; Skuja, Andris; Sharma, Seema; Sherwood, Brian; Shumeiko, Nikolai; Smirnov, Vitaly; Sogut, Kenan; Sonmez, Nasuf; Sorokin, Pavel; Spezziga, Mario; Stefanovich, R; Stolin, Viatcheslav; Sudhakar, Katta; Sulak, Lawrence; Suzuki, Ichiro; Talov, Vladimir; Teplov, Konstantin; Thomas, Ray; Tonwar, Suresh C; Topakli, Huseyin; Tully, Christopher; Turchanovich, L; Ulyanov, A; Vanini, A; Vankov, Ivan; Vardanyan, Irina; Varela, F; Vergili, Mehmet; Verma, Piyush; Vesztergombi, Gyorgy; Vidal, Richard; Vishnevskiy, Alexander; Vlassov, E; Vodopiyanov, Igor; Volobouev, Igor; Volkov, Alexey; Volodko, Anton; Wang, Lei; Werner, Jeremy Scott; Wetstein, Matthew; Winn, Dave; Wigmans, Richard; Whitmore, Juliana; Wu, Shouxiang; Yazgan, Efe; Yetkin, Taylan; Zálán, Peter; Zarubin, Anatoli; Zeyrek, Mehmet

2008-01-01

The CMS hadron calorimeter is a sampling calorimeter with brass absorber and plastic scintillator tiles with wavelength shifting fibres for carrying the light to the readout device. The barrel hadron calorimeter is complemented with an outer calorimeter to ensure high energy shower containment in the calorimeter. Fabrication, testing and calibration of the outer hadron calorimeter are carried out keeping in mind its importance in the energy measurement of jets in view of linearity and resolution. It will provide a net improvement in missing $\\et$ measurements at LHC energies. The outer hadron calorimeter will also be used for the muon trigger in coincidence with other muon chambers in CMS.

Estimation of active pharmaceutical ingredients content using locally weighted partial least squares and statistical wavelength selection.

Science.gov (United States)

Kim, Sanghong; Kano, Manabu; Nakagawa, Hiroshi; Hasebe, Shinji

2011-12-15

Development of quality estimation models using near infrared spectroscopy (NIRS) and multivariate analysis has been accelerated as a process analytical technology (PAT) tool in the pharmaceutical industry. Although linear regression methods such as partial least squares (PLS) are widely used, they cannot always achieve high estimation accuracy because physical and chemical properties of a measuring object have a complex effect on NIR spectra. In this research, locally weighted PLS (LW-PLS) which utilizes a newly defined similarity between samples is proposed to estimate active pharmaceutical ingredient (API) content in granules for tableting. In addition, a statistical wavelength selection method which quantifies the effect of API content and other factors on NIR spectra is proposed. LW-PLS and the proposed wavelength selection method were applied to real process data provided by Daiichi Sankyo Co., Ltd., and the estimation accuracy was improved by 38.6% in root mean square error of prediction (RMSEP) compared to the conventional PLS using wavelengths selected on the basis of variable importance on the projection (VIP). The results clearly show that the proposed calibration modeling technique is useful for API content estimation and is superior to the conventional one. Copyright © 2011 Elsevier B.V. All rights reserved.

On the response of electronic personal dosimeters in constant potential and pulsed X-ray beams

Energy Technology Data Exchange (ETDEWEB)

Guimaraes, Margarete C.; Silva, Teogenes; Silva, Claudete R.E., E-mail: margaretecristinag@gmail.com [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Oliveira, Paulo Marcio C. de [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Anatomia e Imagem

2015-07-01

Electronic personal dosimeters (EPDs) based on solid state detectors have widely been used but some deficiencies in their response in pulsed radiation beams have been reported. Nowadays, there is not an international standard for pulsed X-ray beams for calibration or type testing of dosimeters. Irradiation conditions for testing the response of EPDs in both the constant potential and pulsed X-ray beams were established in CDTN. Three different types of EPDs were tested in different conditions in similar ISO and IEC X-ray qualities. Results stressed the need of performing additional checks before using EPDs in constant potential or pulsed X-rays. (author)

Cross-Calibration of Secondary Electron Multiplier in Noble Gas Analysis

Science.gov (United States)

Santato, Alessandro; Hamilton, Doug; Deerberg, Michael; Wijbrans, Jan; Kuiper, Klaudia; Bouman, Claudia

2015-04-01

The latest generation of multi-collector noble gas mass spectrometers has decisively improved the precision in isotopic ratio analysis [1, 2] and helped the scientific community to address new questions [3]. Measuring numerous isotopes simultaneously has two significant advantages: firstly, any fluctuations in signal intensity have no effect on the isotope ratio and secondly, the analysis time is reduced. This particular point becomes very important in static vacuum mass spectrometry where during the analysis, the signal intensity decays and at the same time the background increases. However, when multi-collector analysis is utilized, it is necessary to pay special attention to the cross calibration of the detectors. This is a key point in order to have accurate and reproducible isotopic ratios. In isotope ratio mass spectrometry, with regard to the type of detector (i.e. Faraday or Secondary Electron Multiplier, SEM), analytical technique (TIMS, MC-ICP-MS or IRMS) and isotope system of interest, several techniques are currently applied to cross-calibrate the detectors. Specifically, the gain of the Faraday cups is generally stable and only the associated amplifier must be calibrated. For example, on the Thermo Scientific instrument control systems, the 1011 and 1012 ohm amplifiers can easily be calibrated through a fully software controlled procedure by inputting a constant electric signal to each amplifier sequentially [4]. On the other hand, the yield of the SEMs can drift up to 0.2% / hour and other techniques such as peak hopping, standard-sample bracketing and multi-dynamic measurement must be used. Peak hopping allows the detectors to be calibrated by measuring an ion beam of constant intensity across the detectors whereas standard-sample bracketing corrects the drift of the detectors through the analysis of a reference standard of a known isotopic ratio. If at least one isotopic pair of the sample is known, multi-dynamic measurement can be used; in this

Development of Web Tools for the automatic Upload of Calibration Data into the CMS Condition Data

Science.gov (United States)

di Guida, Salvatore; Innocente, Vincenzo; Pierro, Antonio

2010-04-01

This article explains the recent evolution of Condition Database Application Service. The Condition Database Application Service is part of the condition database system of the CMS experiment, and it is used for handling and monitoring the CMS detector condition data, and the corresponding computing resources like Oracle Databases, storage service and network devices. We deployed a service, the offline Dropbox service, that will be used by Alignment and Calibration Group in order to upload from the offline network (GPN) the calibration constants produced by running offline analysis.

Improved wavelengths for the 1s2s3S1-1s2p3P0,2 transitions in helium-like Si12+

International Nuclear Information System (INIS)

Armour, I.A.; Myers, E.G.; Silver, J.D.; Traebert, E.; Oxford Univ.

1979-01-01

The wavelengths of the 1s2s 3 S 1 -1s2p 3 P 0 , 2 transitions in He-like Si 12+ have been remaesured to be 87.86 +- 0.01 nm and 81.48 +- 0.01 nm. The use of Rydberg lines for the calibration of fast beam spectra is discussed. (orig.)

Calibration of the Electromagnetic Calorimeter of the ATLAS Experiment and Application to the Measurement of (BE)H Boson Couplings in the Diphoton Channel with Run 2 Data of the LHC

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00436282

The discovery of the Higgs boson was a major success of the run 1 of the LHC. The era of precision measurements began as any deviation from the expected Standard Model (SM) value would be an indirect hint of new physics Beyond the Standard Model (BSM). This is important since no direct evidence was found. This thesis has a first focus on the calibration of the electromagnetic calorimeter of the ATLAS experiment. The final step of this calibration uses the knowledge of the lineshape of the Z boson in order to correct the measured energy of electrons and photons. Recommendations for the beginning of run 2 have been given to provide calibration constants for early analyses. Run 2 calibration constants have been computed and the performances of run 1 have been reached and improved : the systematic uncertainty on the resolution constant term of the electromagnetic calorimeter, which was dominant for the Higgs boson couplings measurement at run 1, has been divided by a factor 3. The measurement of the H boson coupl...

Visible and Mid-Infrared Gypsum Optical Constants for Modeling of Martian Deposits

Science.gov (United States)

Roush, Ted L.; Esposito, Francesca; Rossmann, George R.; Colangeli, Luigi

2007-08-01

Introduction: Recent and on-going remote and in situ observations indicate that sulfates are present in significant abundances at various locations on Mars [1-7]. The Mars Reconnaissance Orbiter (MRO) imaging spectrometer (CRISM) is returning hyperspectral data at higher spatial resolution [8] than the OMEGA instrument on the Mars Express Mission [3]. Data from both OMEGA and CRISM have provided spectral evidence for the presence of gypsum and various hydrated sulfates on the Martian surface [e.g. 3-7] Thus, the optical properties of sulfates, in general, are of interest to quantitative interpretation of this increasing volume of remotely sensed data. This is because optical constants describe how a material interacts with electromagnetic radiation and represent the fundamental values used in radiative transfer calculations describing a variety of physical environments. Such environments include atmospheres where aerosols are present, planetary and satellite regoliths, and circumstellar dust clouds. Here we focus upon gypsum because of its applicability due to its identification on Mars. Also, gypsum is a mineral that is readily available in samples sizes that are suitable for study using a variety of spectral measurements. In the infrared (>5 μm) several studies reporting the optical constants of gypsum can be used in evaluating the approach used here. Most importantly, there is a general lack of data regarding the optical constants for gypsum at visible and mid-infrared wavelengths (0.4-5 μm) that are being observed by OMEGA and CRISM. Background: In the infrared, there have been several studies focused at determining the optical constants of gypsum using classical dispersion models [9-11]. These have used a variety of samples including; crystals, compressed pellets of pure materials, and grains suspended in a KBr matrix. Spectral measurements of gypsum, and other sulfates, have existed for about 100 years at visible and mid-infrared wavelengths (0.4-5 μm) [e

Towards short wavelengths FELs workshop

International Nuclear Information System (INIS)

Ben-Zvi, I.; Winick, H.

1993-01-01

This workshop was caged because of the growing perception in the FEL source community that recent advances have made it possible to extend FEL operation to wavelengths about two orders of magnitude shorter than the 240 nm that has been achieved to date. In addition short wavelength FELs offer the possibilities of extremely high peak power (several gigawatts) and very short pulses (of the order of 100 fs). Several groups in the USA are developing plans for such short wavelength FEL facilities. However, reviewers of these plans have pointed out that it would be highly desirable to first carry out proof-of-principle experiments at longer wavelengths to increase confidence that the shorter wavelength devices will indeed perform as calculated. The need for such experiments has now been broadly accepted by the FEL community. Such experiments were the main focus of this workshop as described in the following objectives distributed to attendees: (1) Define measurements needed to gain confidence that short wavelength FELs will perform as calculated. (2) List possible hardware that could be used to carry out these measurements in the near term. (3) Define a prioritized FEL physics experimental program and suggested timetable. (4) Form collaborative teams to carry out this program

Towards short wavelengths FELs workshop

Science.gov (United States)

Ben-Zvi, I.; Winick, H.

1993-11-01

This workshop was caged because of the growing perception in the FEL source community that recent advances have made it possible to extend FEL operation to wavelengths about two orders of magnitude shorter than the 240 nm that has been achieved to date. In addition short wavelength FEL's offer the possibilities of extremely high peak power (several gigawatts) and very short pulses (of the order of 100 fs). Several groups in the USA are developing plans for such short wavelength FEL facilities. However, reviewers of these plans have pointed out that it would be highly desirable to first carry out proof-of-principle experiments at longer wavelengths to increase confidence that the shorter wavelength devices will indeed perform as calculated. The need for such experiments has now been broadly accepted by the FEL community. Such experiments were the main focus of this workshop as described in the following objectives distributed to attendees: (1) Define measurements needed to gain confidence that short wavelength FEL's will perform as calculated. (2) List possible hardware that could be used to carry out these measurements in the near term. (3) Define a prioritized FEL physics experimental program and suggested timetable. (4) Form collaborative teams to carry out this program.

Enhanced Deformation of Azobenzene-Modified Liquid Crystal Polymers under Dual Wavelength Exposure: A Photophysical Model

Science.gov (United States)

Liu, Ling; Onck, Patrick R.

2017-08-01

Azobenzene-embedded liquid crystal polymers can undergo mechanical deformation in response to ultraviolet (UV) light. The natural rodlike trans state azobenzene absorbs UV light and isomerizes to a bentlike cis state, which disturbs the order of the polymer network, leading to an anisotropic deformation. The current consensus is that the magnitude of the photoinduced deformation is related to the statistical building up of molecules in the cis state. However, a recent experimental study [Liu and Broer, Nat. Commun. 6 8334 (2015)., 10.1038/ncomms9334] shows that a drastic (fourfold) increase of the photoinduced deformation can be generated by exposing the samples simultaneously to 365 nm (UV) and 455 nm (visible) light. To elucidate the physical mechanism that drives this increase, we develop a two-light attenuation model and an optomechanical constitutive relation that not only accounts for the statistical accumulation of cis azobenzenes, but also for the dynamic trans-cis-trans oscillatory isomerization process. Our experimentally calibrated model predicts that the optimal single-wavelength exposure is 395 nm light, a pronounced shift towards the visible spectrum. In addition, we identify a range of optimal combinations of two-wavelength lights that generate a favorable response for a given amount of injected energy. Our model provides mechanistic insight into the different (multi)wavelength exposures used in experiments and, at the same time, opens new avenues towards enhanced, multiwavelength optomechanical behavior.

The Near-infrared Tip of the Red Giant Branch. I. A Calibration in the Isolated Dwarf Galaxy IC 1613

Science.gov (United States)

Madore, Barry F.; Freedman, Wendy L.; Hatt, Dylan; Hoyt, Taylor J.; Monson, Andrew J.; Beaton, Rachael L.; Rich, Jeffrey A.; Jang, In Sung; Lee, Myung Gyoon; Scowcroft, Victoria; Seibert, Mark

2018-05-01

Based on observations from the FourStar near-infrared camera on the 6.5 m Baade-Magellan telescope at Las Campanas, Chile, we present calibrations of the JHK luminosities of stars defining the tip of the red giant branch (TRGB) in the halo of the Local Group dwarf galaxy IC 1613. We employ metallicity-independent (rectified) T-band magnitudes—constructed using J-, H-, and K-band magnitudes and both (J ‑ H) and (J ‑ K) colors to flatten the upward-sloping red giant branch tips as otherwise seen in their apparent color–magnitude diagrams. We describe and quantify the advantages of working at these particular near-infrared wavelengths, which are applicable to both the Hubble Space Telescope (HST) and the James Webb Space Telescope (JWST). We also note that these same wavelengths can be accessed from the ground for an eventual tie-in to Gaia for absolute astrometry and parallaxes to calibrate the intrinsic luminosity of the TRGB. Adopting the color terms derived from the IC 1613 data, as well as the zero points from a companion study of the Large Magellanic Cloud, whose distance is anchored to the geometric distances of detached eclipsing binaries, we find a true distance modulus of 24.32 ± 0.02 (statistical) ±0.05 mag (systematic) for IC 1613, which compares favorably with the recently published multi-wavelength, multi-method consensus modulus of 24.30 ± 0.05 mag by Hatt et al.

Calibrating and preserving the energy scale of the Tile Calorimeter cells during four years of LHC data-taking

CERN Document Server

Dubreuil, E; The ATLAS collaboration

2013-01-01

TileCal is the hadronic calorimeter covering the most central region of ATLAS experiment at the LHC. This sampling calorimeter uses iron plates as absorber and plastic scintillating tiles as the active material. Scintillation light produced in the tiles is transmitted by wavelength shifting fibers to photomultipliers tubes (PMTs). The resulting electronic signals from the approximatively 10000 PMTs are measured and digitized every 25 ns before being transferred to off-detector data-acquisition systems. A set of calibration systems allow to monitor and equalize the calorimeter at each stage of the signal production, from scintillation light to digitization. This calibration suite is based on signal generation from different sources: A Cs radioactive source, laser light, charge injection and charge integration over thousands of bunch crossings of minimum bias events produced in proton-proton collisions. This contribution presents a brief description of the different TileCal calibration systems and their perform...

Exposure-rate calibration using large-area calibration pads

International Nuclear Information System (INIS)

Novak, E.F.

1988-09-01

The US Department of Energy (DOE) Office of Remedial Action and Waste Technology established the Technical Measurements Center (TMC) at the DOE Grand Junction Projects Office (GJPO) in Grand Junction, Colorado, to standardize, calibrate, and compare measurements made in support of DOE remedial action programs. A set of large-area, radioelement-enriched concrete pads was constructed by the DOE in 1978 at the Walker Field Airport in Grand Junction for use as calibration standards for airborne gamma-ray spectrometer systems. The use of these pads was investigated by the TMC as potential calibration standards for portable scintillometers employed in measuring gamma-ray exposure rates at Uranium Mill Tailings Remedial Action (UMTRA) project sites. Data acquired on the pads using a pressurized ionization chamber (PIC) and three scintillometers are presented as an illustration of an instrumental calibration. Conclusions and recommended calibration procedures are discussed, based on the results of these data

SeaWiFS calibration and validation plan, volume 3

International Nuclear Information System (INIS)

Hooker, S.B.; Firestone, E.R.; Mcclain, C.R.; Esaias, W.E.; Barnes, W.; Guenther, B.; Endres, D.; Mitchell, B.G.; Barnes, R.

1992-09-01

The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) will be the first ocean-color satellite since the Nimbus-7 Coastal Zone Color Scanner (CZCS), which ceased operation in 1986. Unlike the CZCS, which was designed as a proof-of-concept experiment, SeaWiFS will provide routine global coverage every 2 days and is designed to provide estimates of photosynthetic concentrations of sufficient accuracy for use in quantitative studies of the ocean's primary productivity and biogeochemistry. A review of the CZCS mission is included that describes that data set's limitations and provides justification for a comprehensive SeaWiFS calibration and validation program. To accomplish the SeaWiFS scientific objectives, the sensor's calibration must be constantly monitored, and robust atmospheric corrections and bio-optical algorithms must be developed. The plan incorporates a multi-faceted approach to sensor calibration using a combination of vicarious (based on in situ observations) and onboard calibration techniques. Because of budget constraints and the limited availability of ship resources, the development of the operational algorithms (atmospheric and bio-optical) will rely heavily on collaborations with the Earth Observing System (EOS), the Moderate Resolution Imaging Spectrometer (MODIS) oceans team, and projects sponsored by other agencies, e.g., the U.S. Navy and the National Science Foundation (NSF). Other elements of the plan include the routine quality control of input ancillary data (e.g., surface wind, surface pressure, ozone concentration, etc.) used in the processing and verification of the level-0 (raw) data to level-1 (calibrated radiances), level-2 (derived products), and level-3 (gridded and averaged derived data) products

A new calibration method for tri-axial field sensors in strap-down navigation systems

International Nuclear Information System (INIS)

Li, Xiang; Li, Zhi

2012-01-01

This paper presents a novel calibration method for tri-axial field sensors, such as magnetometers and accelerometers, in strap-down navigation systems. Strap-down tri-axial sensors have been widely used as they have the advantages of small size and low cost, but they need to be calibrated in order to ensure their accuracy. The most commonly used calibration method for a tri-axial field sensor is based on ellipsoid fitting, which has no requirement for external references. However, the self-calibration based on ellipsoid fitting is unable to determine and compensate the mutual misalignment between different sensors in a multi-sensor system. Therefore, a novel calibration method that employs the invariance of the dot product of two constant vectors is introduced in this paper. The proposed method, which is named dot product invariance method, brings a complete solution for the error model of tri-axial field sensors, and can solve the problem of alignment in a multi-sensor system. Its effectiveness and superiority over the ellipsoid fitting method are illustrated by numerical simulations, and its application on a digital magnetic compass shows significant enhancement of the heading accuracy. (paper)

The "+" for CRIRES: enabling better science at infrared wavelength and high spectral resolution at the ESO VLT

Science.gov (United States)

Dorn, Reinhold J.; Follert, Roman; Bristow, Paul; Cumani, Claudio; Eschbaumer, Siegfried; Grunhut, Jason; Haimerl, Andreas; Hatzes, Artie; Heiter, Ulrike; Hinterschuster, Renate; Ives, Derek J.; Jung, Yves; Kerber, Florian; Klein, Barbara; Lavaila, Alexis; Lizon, Jean Louis; Löwinger, Tom; Molina-Conde, Ignacio; Nicholson, Belinda; Marquart, Thomas; Oliva, Ernesto; Origlia, Livia; Pasquini, Luca; Paufique, Jérôme; Piskunov, Nikolai; Reiners, Ansgar; Seemann, Ulf; Stegmeier, Jörg; Stempels, Eric; Tordo, Sebastien

2016-08-01

The adaptive optics (AO) assisted CRIRES instrument is an IR (0.92 - 5.2 μm) high-resolution spectrograph was in operation from 2006 to 2014 at the Very Large Telescope (VLT) observatory. CRIRES was a unique instrument, accessing a parameter space (wavelength range and spectral resolution) up to now largely uncharted. It consisted of a single-order spectrograph providing long-slit (40 arcsecond) spectroscopy with a resolving power up to R=100 000. However the setup was limited to a narrow, single-shot, spectral range of about 1/70 of the central wavelength, resulting in low observing efficiency for many scientific programmes requiring a broad spectral coverage. The CRIRES upgrade project, CRIRES+, transforms this VLT instrument into a cross-dispersed spectrograph to increase the simultaneously covered wavelength range by a factor of ten. A new and larger detector focal plane array of three Hawaii 2RG detectors with 5.3 μm cut-off wavelength will replace the existing detectors. For advanced wavelength calibration, custom-made absorption gas cells and an etalon system will be added. A spectro-polarimetric unit will allow the recording of circular and linear polarized spectra. This upgrade will be supported by dedicated data reduction software allowing the community to take full advantage of the new capabilities offered by CRIRES+. CRIRES+ has now entered its assembly and integration phase and will return with all new capabilities by the beginning of 2018 to the Very Large Telescope in Chile. This article will provide the reader with an update of the current status of the instrument as well as the remaining steps until final installation at the Paranal Observatory.

Radiolytic modelling of spent fuel oxidative dissolution mechanism. Calibration against UO2 dynamic leaching experiments

International Nuclear Information System (INIS)

Merino, J.; Cera, E.; Bruno, J.; Quinones, J.; Casas, I.; Clarens, F.; Gimenez, J.; Pablo, J. de; Rovira, M.; Martinez-Esparza, A.

2005-01-01

Calibration and testing are inherent aspects of any modelling exercise and consequently they are key issues in developing a model for the oxidative dissolution of spent fuel. In the present work we present the outcome of the calibration process for the kinetic constants of a UO 2 oxidative dissolution mechanism developed for using in a radiolytic model. Experimental data obtained in dynamic leaching experiments of unirradiated UO 2 has been used for this purpose. The iterative calibration process has provided some insight into the detailed mechanism taking place in the alteration of UO 2 , particularly the role of · OH radicals and their interaction with the carbonate system. The results show that, although more simulations are needed for testing in different experimental systems, the calibrated oxidative dissolution mechanism could be included in radiolytic models to gain confidence in the prediction of the long-term alteration rate of the spent fuel under repository conditions

A current-steering self-calibration 14-bit 100-MSPs DAC

International Nuclear Information System (INIS)

Qiu Dong; Fang Sheng; Li Ran; Xie Renzhong; Yi Ting; Hong Zhfflang

2010-01-01

This paper presents the design and implementation of a 14-bit, 100 MS/s CMOS digital-to-analog converter (DAC). Analog background self-calibration based on the concept of analog current trimming is introduced. A constant clock load switch driver, a calibration period randomization circuit and a return-to-zero output stage have been adopted to improve the dynamic performance. The chip has been manufactured in a SMIC 0.13-μm process and occupies 1.33 x 0.97 mm 2 of the core area. The current consumption is 50 mA under 1.2/3.3 V dual power supplies for digital and analog, respectively. The measured differential and integral nonlinearity is 3.1 LSB and 4.3 LSB, respectively. The SFDR is 72.8 dB at a 1 MHz signal and a 100 MHz sampling frequency. (semiconductor integrated circuits)

Making Displaced Holograms At Two Wavelengths

Science.gov (United States)

Witherow, William K.; Ecker, Andreas

1989-01-01

Two-wavelength holographic system augmented with pair of prisms to introduce small separation between holograms formed simultaneously at two wavelengths on holographic plate. Principal use in study of flows. Gradients in index of refraction of fluid caused by variations in temperature, concentration, or both. Holography at one wavelength cannot be used to distinguish between two types of variations. Difference between spacings of fringes in photographs reconstructed from holograms taken simultaneously at two different wavelengths manipulated mathematically to determine type of variation.

PTB’s radiometric scales for UV and VUV source calibration based on synchrotron radiation

Science.gov (United States)

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

2018-06-01

The radiant intensity of synchrotron radiation can be accurately calculated with classical electrodynamics. This primary realization of the spectral radiant intensity has been used by PTB at several electron storage rings which have been optimized to be operated as primary source standards for the calibration of transfer sources in the spectral range of UV and VUV for almost 30 years. The transfer sources are compared to the primary source standard by means of suitable wavelength-dispersive transfer stations. The spectral range covered by deuterium lamps, which represent transfer sources that are easy to handle, is of particular relevance in practice. Here, we report on developments in the realization and preservation of the radiometric scales for spectral radiant intensity and spectral radiance in the wavelength region from 116 nm to 400 nm, based on a set of deuterium reference lamps, over the last few decades. An inside view and recommendations on the operation of the D2 lamps used for the realization of the radiometric scale are presented. The data has been recently compiled to illustrate the chronological behaviour at various wavelengths. Moreover, an overview of the internal and external validation measurements and intercomparisons is given.

Wavelength dependence of interstellar polarization

International Nuclear Information System (INIS)

Mavko, G.E.

1974-01-01

The wavelength dependence of interstellar polarization was measured for twelve stars in three regions of the Milky Way. A 120A bandpass was used to measure the polarization at a maximum of sixteen wavelengths evenly spaced between 2.78μ -1 (3600A) and 1.28μ -1 (7800A). For such a wide wavelength range, the wavelength resolution is superior to that of any previously reported polarization measurements. The new scanning polarimeter built by W. A. Hiltner of the University of Michigan was used for the observations. Very broad structure was found in the wavelength dependence of the polarization. Extensive investigations were carried out to show that the structure was not caused by instrumental effects. The broad structure observed is shown to be in agreement with concurrent extinction measurements for the same stars. Also, the observed structure is of the type predicted when a homogeneous silicate grain model is fitted to the observed extinction. The results are in agreement with the hypothesis that the very broad band structure seen in the extinction is produced by the grains. (Diss. Abstr. Int., B)

The cost of uniqueness in groundwater model calibration

Science.gov (United States)

Moore, Catherine; Doherty, John

2006-04-01

Calibration of a groundwater model requires that hydraulic properties be estimated throughout a model domain. This generally constitutes an underdetermined inverse problem, for which a solution can only be found when some kind of regularization device is included in the inversion process. Inclusion of regularization in the calibration process can be implicit, for example through the use of zones of constant parameter value, or explicit, for example through solution of a constrained minimization problem in which parameters are made to respect preferred values, or preferred relationships, to the degree necessary for a unique solution to be obtained. The "cost of uniqueness" is this: no matter which regularization methodology is employed, the inevitable consequence of its use is a loss of detail in the calibrated field. This, in turn, can lead to erroneous predictions made by a model that is ostensibly "well calibrated". Information made available as a by-product of the regularized inversion process allows the reasons for this loss of detail to be better understood. In particular, it is easily demonstrated that the estimated value for an hydraulic property at any point within a model domain is, in fact, a weighted average of the true hydraulic property over a much larger area. This averaging process causes loss of resolution in the estimated field. Where hydraulic conductivity is the hydraulic property being estimated, high averaging weights exist in areas that are strategically disposed with respect to measurement wells, while other areas may contribute very little to the estimated hydraulic conductivity at any point within the model domain, this possibly making the detection of hydraulic conductivity anomalies in these latter areas almost impossible. A study of the post-calibration parameter field covariance matrix allows further insights into the loss of system detail incurred through the calibration process to be gained. A comparison of pre- and post-calibration

The laser-based calibration system of delta spectrometer

Energy Technology Data Exchange (ETDEWEB)

Malakhov, A.I. [Veksler and Baldin Laboratory of High Energies, JINR, Dubna (Russian Federation); Anisimov, Yu.S. [Veksler and Baldin Laboratory of High Energies, JINR, Dubna (Russian Federation); Gmuca, S. [Inst. of Physics, SAS, Bratislava (Slovakia); Kizka, V.A. [Veksler and Baldin Laboratory of High Energies, JINR, Dubna (Russian Federation); Kliman, J. [Veksler and Baldin Laboratory of High Energies, JINR, Dubna (Russian Federation); Inst. of Physics, SAS, Bratislava (Slovakia); Krasnov, V.A. [Veksler and Baldin Laboratory of High Energies, JINR, Dubna (Russian Federation); Kurepin, A.B. [Inst. for Nuclear Research RAS, Moscow (Russian Federation); Kuznetsov, S.N. [Veksler and Baldin Laboratory of High Energies, JINR, Dubna (Russian Federation); Livanov, A.N. [Veksler and Baldin Laboratory of High Energies, JINR, Dubna (Russian Federation); Matousek, V. [Inst. of Physics, SAS, Bratislava (Slovakia); Morhac, M. [Inst. of Physics, SAS, Bratislava (Slovakia)]. E-mail: Miroslav.Morhac@savba.sk; Turzo, I. [Inst. of Physics, SAS, Bratislava (Slovakia)

2006-10-15

We present a report on a laser calibration system of DELTA spectrometer that has been designed and developed in the Laboratory of High Energies, JINR, Dubna. The system is intended for monitoring and continuous stabilization of the outputs of the detectors of the spectrometer. The UV nitrogen pulse laser along with optical filters, collection of optical fibers and plastic scintillators serving for conversion of UV light pulses to longer wavelength and for diffusion of the light beam to illuminate 300 photomultipliers are used. We stabilize the positions of laser peaks by corrections of high voltages of the corresponding photomultipliers. The proposed system allows one to accomplish the stabilization during the experiment with the use of the same electronics. The control software together with the first results from test runs are described as well.

The JANA calibrations and conditions database API

International Nuclear Information System (INIS)

Lawrence, David

2010-01-01

Calibrations and conditions databases can be accessed from within the JANA Event Processing framework through the API defined in its JCalibration base class. The API is designed to support everything from databases, to web services to flat files for the backend. A Web Service backend using the gSOAP toolkit has been implemented which is particularly interesting since it addresses many modern cybersecurity issues including support for SSL. The API allows constants to be retrieved through a single line of C++ code with most of the context, including the transport mechanism, being implied by the run currently being analyzed and the environment relieving developers from implementing such details.

The JANA calibrations and conditions database API

Energy Technology Data Exchange (ETDEWEB)

Lawrence, David, E-mail: davidl@jlab.or [12000 Jefferson Ave., Suite 8, Newport News, VA 23601 (United States)

2010-04-01

Calibrations and conditions databases can be accessed from within the JANA Event Processing framework through the API defined in its JCalibration base class. The API is designed to support everything from databases, to web services to flat files for the backend. A Web Service backend using the gSOAP toolkit has been implemented which is particularly interesting since it addresses many modern cybersecurity issues including support for SSL. The API allows constants to be retrieved through a single line of C++ code with most of the context, including the transport mechanism, being implied by the run currently being analyzed and the environment relieving developers from implementing such details.

Measurement of the Boltzmann constant by Johnson noise thermometry using a superconducting integrated circuit

Science.gov (United States)

Urano, C.; Yamazawa, K.; Kaneko, N.-H.

2017-12-01

We report on our measurement of the Boltzmann constant by Johnson noise thermometry (JNT) using an integrated quantum voltage noise source (IQVNS) that is fully implemented with superconducting integrated circuit technology. The IQVNS generates calculable pseudo white noise voltages to calibrate the JNT system. The thermal noise of a sensing resistor placed at the temperature of the triple point of water was measured precisely by the IQVNS-based JNT. We accumulated data of more than 429 200 s in total (over 6 d) and used the Akaike information criterion to estimate the fitting frequency range for the quadratic model to calculate the Boltzmann constant. Upon detailed evaluation of the uncertainty components, the experimentally obtained Boltzmann constant was k=1.380 6436× {{10}-23} J K-1 with a relative combined uncertainty of 10.22× {{10}-6} . The value of k is relatively -3.56× {{10}-6} lower than the CODATA 2014 value (Mohr et al 2016 Rev. Mod. Phys. 88 035009).

Cosmological Hubble constant and nuclear Hubble constant

International Nuclear Information System (INIS)

Horbuniev, Amelia; Besliu, Calin; Jipa, Alexandru

2005-01-01

The evolution of the Universe after the Big Bang and the evolution of the dense and highly excited nuclear matter formed by relativistic nuclear collisions are investigated and compared. Values of the Hubble constants for cosmological and nuclear processes are obtained. For nucleus-nucleus collisions at high energies the nuclear Hubble constant is obtained in the frame of different models involving the hydrodynamic flow of the nuclear matter. Significant difference in the values of the two Hubble constant - cosmological and nuclear - is observed

Topology optimised wavelength dependent splitters

DEFF Research Database (Denmark)

Hede, K. K.; Burgos Leon, J.; Frandsen, Lars Hagedorn

A photonic crystal wavelength dependent splitter has been constructed by utilising topology optimisation1. The splitter has been fabricated in a silicon-on-insulator material (Fig. 1). The topology optimised wavelength dependent splitter demonstrates promising 3D FDTD simulation results....... This complex photonic crystal structure is very sensitive against small fabrication variations from the expected topology optimised design. A wavelength dependent splitter is an important basic building block for high-performance nanophotonic circuits. 1J. S. Jensen and O. Sigmund, App. Phys. Lett. 84, 2022...

Simultaneous estimation of diet composition and calibration coefficients with fatty acid signature data

Science.gov (United States)

Bromaghin, Jeffrey F.; Budge, Suzanne M.; Thiemann, Gregory W.; Rode, Karyn D.

2017-01-01

Knowledge of animal diets provides essential insights into their life history and ecology, although diet estimation is challenging and remains an active area of research. Quantitative fatty acid signature analysis (QFASA) has become a popular method of estimating diet composition, especially for marine species. A primary assumption of QFASA is that constants called calibration coefficients, which account for the differential metabolism of individual fatty acids, are known. In practice, however, calibration coefficients are not known, but rather have been estimated in feeding trials with captive animals of a limited number of model species. The impossibility of verifying the accuracy of feeding trial derived calibration coefficients to estimate the diets of wild animals is a foundational problem with QFASA that has generated considerable criticism. We present a new model that allows simultaneous estimation of diet composition and calibration coefficients based only on fatty acid signature samples from wild predators and potential prey. Our model performed almost flawlessly in four tests with constructed examples, estimating both diet proportions and calibration coefficients with essentially no error. We also applied the model to data from Chukchi Sea polar bears, obtaining diet estimates that were more diverse than estimates conditioned on feeding trial calibration coefficients. Our model avoids bias in diet estimates caused by conditioning on inaccurate calibration coefficients, invalidates the primary criticism of QFASA, eliminates the need to conduct feeding trials solely for diet estimation, and consequently expands the utility of fatty acid data to investigate aspects of ecology linked to animal diets.

Influence of Poisson's ratio variation on lateral spring constant of atomic force microscopy cantilevers

International Nuclear Information System (INIS)

Yeh, M.-K.; Tai, N.-Ha; Chen, B.-Y.

2008-01-01

Atomic force microscopy (AFM) can be used to measure the surface morphologies and the mechanical properties of nanostructures. The force acting on the AFM cantilever can be obtained by multiplying the spring constant of AFM cantilever and the corresponding deformation. To improve the accuracy of force experiments, the spring constant of AFM cantilever must be calibrated carefully. Many methods, such as theoretical equations, the finite element method, and the use of reference cantilever, were reported to obtain the spring constant of AFM cantilevers. For the cantilever made of single crystal, the Poisson's ratio varies with different cantilever-crystal angles. In this paper, the influences of Poisson's ratio variation on the lateral spring constant and axial spring constant of rectangular and V-shaped AFM cantilevers, with different tilt angles and normal forces, were investigated by the finite element analysis. When the cantilever's tilt angle is 20 deg. and the Poisson's ratio varies from 0.02 to 0.4, the finite element results show that the lateral spring constants decrease 11.75% for the rectangular cantilever with 1 μN landing force and decrease 18.60% for the V-shaped cantilever with 50 nN landing force, respectively. The influence of Poisson's ratio variation on axial spring constant is less than 3% for both rectangular and V-shaped cantilevers. As the tilt angle increases, the axial spring constants for rectangular and V-shaped cantilevers decrease substantially. The results obtained can be used to improve the accuracy of the lateral force measurement when using atomic force microscopy

The Upgraded Calibration System for the Scintillator-PMT Tile Hadronic Calorimeter of the ATLAS experiment at CERN/LHC

CERN Document Server

Chakraborty, Dhiman; The ATLAS collaboration

2017-01-01

The ATLAS Tile Calorimeter (TileCal) is the central section of the hadronic calorimeter of the ATLAS experiment and provides important information for reconstruction of hadrons, jets, hadronic decays of tau leptons and missing transverse energy in highest energy proton-proton and heavy-ion collisions at CERN’s Large Hadron Collider. This sampling calorimeter uses steel plates as absorber and scintillating tiles as active medium. The light produced by the passage of charged particles is transmitted by wavelength shifting fibres to photomultiplier tubes (PMTs) located on the outside of the calorimeter. The readout is segmented into about 5000 cells (longitudinally and transversally), each read out by two PMTs in parallel. A multi-component calibration system is employed to calibrate and monitor the stability and performance of each part of the readout chain during data taking. The TileCal calibration system comprises Cesium radioactive sources, laser and charge injection elements and it allows to monitor and ...

The upgraded calibration system for the scintillator-PMT Tile Hadronic Calorimeter of the ATLAS experiment at CERN/LHC

CERN Document Server

Chakraborty, Dhiman; The ATLAS collaboration

2017-01-01

The ATLAS Tile Calorimeter (TileCal) is the central section of the hadronic calorimeter of the ATLAS experiment and provides important information for reconstruction of hadrons, jets, hadronic decays of tau leptons and missing transverse energy in highest energy proton-proton and heavy-ion collisions at CERN’s Large Hadron Collider. This sampling calorimeter uses steel plates as absorber and scintillating tiles as active medium. The light produced by the passage of charged particles is transmitted by wavelength shifting fibres to photomultiplier tubes (PMTs) located on the outside of the calorimeter. The readout is segmented into about 5000 cells (longitudinally and transversally), each read out by two PMTs in parallel. A multi-component calibration system is employed to calibrate and monitor the stability and performance of each part of the readout chain during data taking. The TileCal calibration system comprises Cesium radioactive sources, laser and charge injection elements and it allows to monitor and ...

Variable Acceleration Force Calibration System (VACS)

Science.gov (United States)

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

The propagation of ionization waves - influenced by irradiation of suitable wavelength

International Nuclear Information System (INIS)

Weltmann, K.D.; Deutsch, H.; Schmeissel, J.; Wilke, C.

1995-01-01

The impact of external irradiation mainly at metastable transitions on the propagation of ionization waves in the positive column of a neon a low discharge is investigated. Effects of hysteresis, regions of existence of moving striations and the static current/voltage characteristic depending on the external circuit and on the axial location of the applied irradiation are observed experimentally. The many published experimental contributions show that the presence of striations - either standing or moving - is the normal situation in the diffusion range of pressure and that the homogeneous (i.e. striation free) positive column is the exception existing only for a limited range of currents and pressures. A slight change of one or the other of these parameters results in a transition from the homogeneous column to one containing moving striations or vice versa. Different types of moving striations are known (p-,r- and s- waves) which differ in the product of wavelength λ and the electric field strength E (Novak-constant). It is assumed, that the metastable atoms are responsible for the appearance of p-waves and therefore the discharge was operated at a pressure of p 0 = 1,7 Torr-cm and dc-discharge currents i 0 = 1-20 mA. The length of the glass discharge tube was 1 = 500 mm with radius r 0 = 1 cm. A hollow cathode and a plane electrode were used. The external resistance was varied between 20 kOhm and 1 MOhm additionally. The radiation of suitable wavelength was generated by a second discharge tube with emissive electrodes operated at a pressure of about 5 Torr-cm and discharge currents between 0,5A and 2A. Two hollow mirrors where the open-quote radiation-tube close-quote was centered between, guaranteed a constant light intensity around the investigated tube

Quantitative analysis of titanium concentration using calibration-free laser-induced breakdown spectroscopy (LIBS)

Science.gov (United States)

Zaitun; Prasetyo, S.; Suliyanti, M. M.; Isnaeni; Herbani, Y.

2018-03-01

Laser-induced breakdown spectroscopy (LIBS) can be used for quantitative and qualitative analysis. Calibration-free LIBS (CF-LIBS) is a method to quantitatively analyze concentration of elements in a sample in local thermodynamic equilibrium conditions without using available matrix-matched calibration. In this study, we apply CF-LIBS for quantitative analysis of Ti in TiO2 sample. TiO2 powder sample was mixed with polyvinyl alcohol and formed into pellets. An Nd:YAG pulsed laser at a wavelength of 1064 nm was focused onto the sample to generate plasma. The spectrum of plasma was recorded using spectrophotometer then compared to NIST spectral line to determine energy levels and other parameters. The value of plasma temperature obtained using Boltzmann plot is 8127.29 K and electron density from calculation is 2.49×1016 cm-3. Finally, the concentration of Ti in TiO2 sample from this study is 97% that is in proximity with the sample certificate.

Calibration of Raman lidar water vapor profiles by means of AERONET photometer observations and GDAS meteorological data

Science.gov (United States)

Dai, Guangyao; Althausen, Dietrich; Hofer, Julian; Engelmann, Ronny; Seifert, Patric; Bühl, Johannes; Mamouri, Rodanthi-Elisavet; Wu, Songhua; Ansmann, Albert

2018-05-01

We present a practical method to continuously calibrate Raman lidar observations of water vapor mixing ratio profiles. The water vapor profile measured with the multiwavelength polarization Raman lidar class="text">PollyXT is calibrated by means of co-located AErosol RObotic NETwork (AERONET) sun photometer observations and Global Data Assimilation System (GDAS) temperature and pressure profiles. This method is applied to lidar observations conducted during the Cyprus Cloud Aerosol and Rain Experiment (CyCARE) in Limassol, Cyprus. We use the GDAS temperature and pressure profiles to retrieve the water vapor density. In the next step, the precipitable water vapor from the lidar observations is used for the calibration of the lidar measurements with the sun photometer measurements. The retrieved calibrated water vapor mixing ratio from the lidar measurements has a relative uncertainty of 11 % in which the error is mainly caused by the error of the sun photometer measurements. During CyCARE, nine measurement cases with cloud-free and stable meteorological conditions are selected to calculate the precipitable water vapor from the lidar and the sun photometer observations. The ratio of these two precipitable water vapor values yields the water vapor calibration constant. The calibration constant for the class="text">PollyXT Raman lidar is 6.56 g kg-1 ± 0.72 g kg-1 (with a statistical uncertainty of 0.08 g kg-1 and an instrumental uncertainty of 0.72 g kg-1). To check the quality of the water vapor calibration, the water vapor mixing ratio profiles from the simultaneous nighttime observations with Raman lidar and Vaisala radiosonde sounding are compared. The correlation of the water vapor mixing ratios from these two instruments is determined by using all of the 19 simultaneous nighttime measurements during CyCARE. Excellent agreement with the slope of 1.01 and the R2 of 0.99 is found. One example is presented to demonstrate the full potential of a well-calibrated Raman

The time-walk of analog constant fraction discriminators using very fast scintillator detectors with linear and non-linear energy response

Energy Technology Data Exchange (ETDEWEB)

Regis, J.-M., E-mail: regis@ikp.uni-koeln.de [Institut fuer Kernphysik der Universitaet zu Koeln, Zuelpicher Str. 77, 50937 Koeln (Germany); Rudigier, M.; Jolie, J.; Blazhev, A.; Fransen, C.; Pascovici, G.; Warr, N. [Institut fuer Kernphysik der Universitaet zu Koeln, Zuelpicher Str. 77, 50937 Koeln (Germany)

2012-08-21

The electronic {gamma}-{gamma} fast timing technique allows for direct nuclear lifetime determination down to the few picoseconds region by measuring the time difference between two coincident {gamma}-ray transitions. Using high resolution ultra-fast LaBr{sub 3}(Ce) scintillator detectors in combination with the recently developed mirror symmetric centroid difference method, nuclear lifetimes are measured with a time resolving power of around 5 ps. The essence of the method is to calibrate the energy dependent position (centroid) of the prompt response function of the setup which is obtained for simultaneously occurring events. This time-walk of the prompt response function induced by the analog constant fraction discriminator has been determined by systematic measurements using different photomultiplier tubes and timing adjustments of the constant fraction discriminator. We propose a universal calibration function which describes the time-walk or the combined {gamma}-{gamma} time-walk characteristics, respectively, for either a linear or a non-linear amplitude versus energy dependency of the scintillator detector output pulses.

Comparison of methods of calibration of a neutron probe by gravimetry or neutron-capture model

International Nuclear Information System (INIS)

Vachaud, G.; Royer, J.M.; Cooper, J.D.

1977-01-01

This paper presents a systematic analysis of two methods used for determining calibration curves of neutron probes. The uncertainties resulting from the use of the gravimetric method, with a linear correlation between count rates and water content of soil samples, are considered first. Particular care is given to the determination of errors in the values of water content and count rates, and to the difficulties arising from the choice of the correlation technique. The neutron-calibration curve of the soil was also obtained with a technique based on the determination of neutron thermal adsorption and diffusion constants. The importance of errors associated with this method is also analyzed. Different field examples are then presented. It appears that the neutron-capture technique should be particularly well suited for determining the calibration curve of clay soils or heterogeneous materials for which the gravimetric calibration technique cannot be applied with confidence. On the other hand, it is also shown that for a soil with a very well-defined gravimetric calibration curve, the neutron-capture technique gives results still at least as good as with the former method

Characteristics of prepared gamma-ray calibration sources for radioactivity measurement of environmental and radiation control samples

International Nuclear Information System (INIS)

Samat, S.B.; Oi, Yoshihiro; Taki, Mitsumasa; Manabe, Iwao; Yoshida, Makoto; Minami, Kentaro

1995-03-01

Several types of calibration source having different density were prepared using one or combinations of those materials, namely foam cement, liquid, glass beads, polystyrene foam bead and hard plastic bead for gamma-ray spectrometry of the samples with different densities and shapes(variable height with constant base area). For each type of the source, a few sources were prepared to examine characteristics in such cases as (a) different heights but constant density, and (b) constant height and constant density. For the foam cement source, several sources with different densities and a constant height were prepared. All the sources were measured with a gamma-ray spectrometry system and the results were discussed. This report also presents the results obtained from the experiments for the evaluation of (1) the variation of detector efficiency-energy with gamma-ray energy, and (2) the variation of detector efficiency with density of the sources. (author)

Observed solar near UV variability: A contribution to variations of the solar constant

International Nuclear Information System (INIS)

London, J.; Pap, J.; Rottman, G.J.

1989-01-01

Continuous Measurements of the Solar UV have been made by an instrument on the Solar Mesosphere Explorer (SME) since October 1981. The results for the wavelength interval 200 to 300 nm show an irradiance decrease to a minimum in early 1987 and a subsequent increase to mid-April 1989. The observed UV changes during part of solar cycles 21 to 22 represent approx. 35 percent (during the decreasing phase) and 25 percent (during the increasing phase) of the observed variations of the solar constant for the same time period as the SME measurements

A robust calibration technique for acoustic emission systems based on momentum transfer from a ball drop

Science.gov (United States)

McLaskey, Gregory C.; Lockner, David A.; Kilgore, Brian D.; Beeler, Nicholas M.

2015-01-01

We describe a technique to estimate the seismic moment of acoustic emissions and other extremely small seismic events. Unlike previous calibration techniques, it does not require modeling of the wave propagation, sensor response, or signal conditioning. Rather, this technique calibrates the recording system as a whole and uses a ball impact as a reference source or empirical Green’s function. To correctly apply this technique, we develop mathematical expressions that link the seismic moment $M_{0}$ of internal seismic sources (i.e., earthquakes and acoustic emissions) to the impulse, or change in momentum $\\Delta p $, of externally applied seismic sources (i.e., meteor impacts or, in this case, ball impact). We find that, at low frequencies, moment and impulse are linked by a constant, which we call the force‐moment‐rate scale factor $C_{F\\dot{M}} = M_{0}/\\Delta p$. This constant is equal to twice the speed of sound in the material from which the seismic sources were generated. Next, we demonstrate the calibration technique on two different experimental rock mechanics facilities. The first example is a saw‐cut cylindrical granite sample that is loaded in a triaxial apparatus at 40 MPa confining pressure. The second example is a 2 m long fault cut in a granite sample and deformed in a large biaxial apparatus at lower stress levels. Using the empirical calibration technique, we are able to determine absolute source parameters including the seismic moment, corner frequency, stress drop, and radiated energy of these magnitude −2.5 to −7 seismic events.

Calibration of the OPAL jet chamber with UV laser beams. Measurement of the beam position with position-sensitive silicon diodes (PSD)

International Nuclear Information System (INIS)

Koch, J.

1990-03-01

The OPAL jet chamber is calibrated with tracks produced by UV laser beams. Lateral effect diodes are used for monitoring the laser beam location in the detector. These position sensitive detectors locate the point of impact in two dimensions by the charge division method. Measurements on several diodes were carried out in order to calibrate these devices and to investigate to observed pin-cushion distortion. Using the telegraphers equation suitable expressions were obtained for describing the observed behaviour. It was shown that the magnetic field of OPAL as well as the UV laser wavelength and puls duration had no influence on the position information. (orig.)

A current-steering self-calibration 14-bit 100-MSPs DAC

Energy Technology Data Exchange (ETDEWEB)

Qiu Dong; Fang Sheng; Li Ran; Xie Renzhong; Yi Ting; Hong Zhfflang, E-mail: yiting@fudan.edu.cn [State Key Laboratory of ASIC and System, Fudan University, Shanghai 201203 (China)

2010-12-15

This paper presents the design and implementation of a 14-bit, 100 MS/s CMOS digital-to-analog converter (DAC). Analog background self-calibration based on the concept of analog current trimming is introduced. A constant clock load switch driver, a calibration period randomization circuit and a return-to-zero output stage have been adopted to improve the dynamic performance. The chip has been manufactured in a SMIC 0.13-{mu}m process and occupies 1.33 x 0.97 mm{sup 2} of the core area. The current consumption is 50 mA under 1.2/3.3 V dual power supplies for digital and analog, respectively. The measured differential and integral nonlinearity is 3.1 LSB and 4.3 LSB, respectively. The SFDR is 72.8 dB at a 1 MHz signal and a 100 MHz sampling frequency. (semiconductor integrated circuits)

Calibration of a Microwave Imaging System Using a Known Scatterer

DEFF Research Database (Denmark)

Rubæk, Tonny; Zhurbenko, Vitaliy

2010-01-01

the transmission and receiving channels inside of the transceiver modules has been detected. This is most likely caused by the lessthan- perfect isolation of the switches in the modules as well as leakage through the PCB itself. Since the presence of such a leakage signal in the measurements seriously influence...... that the low-amplitude RF signals, available at the terminals of the antennas, only need to travel a very short distance to get to the low-noise amplifier, while the RF as well as the IF signals running to and from the transceiver modules all have significant amplitudes. However, some leakage between...... the imaging capability of the system, it is of interest to remove it. In this work, a calibration procedure capable of removing a constant offset, i.e., the leakage, from the measured signals is presented. The calibration procedure is based on a comparison between the relative change observed between...

Validation of a densimeter calibration procedure for a secondary calibration laboratory

International Nuclear Information System (INIS)

Alpizar Herrera, Juan Carlos

2014-01-01

A survey was conducted to quantify the need for calibration of a density measurement instrument at the research units at the Sede Rodrigo Facio of the Universidad de Costa Rica. A calibration procedure was documented for the instrument that presented the highest demand in the survey by the calibration service. A study of INTE-ISO/IEC 17025: 2005 and specifically in section 5.4 of this standard was done, to document the procedure for calibrating densimeters. Densimeter calibration procedures and standards were sought from different national and international sources. The method of hydrostatic weighing or Cuckow method was the basis of the defined procedure. Documenting the calibration procedure and creating other documents was performed for data acquisition log, intermediate calculation log and calibration certificate copy. A veracity test was performed using as reference laboratory a laboratory of calibration secondary national as part of the validation process of the documented procedure. The results of the E_n statistic of 0.41; 0.34 and 0.46 for the calibration points 90%, 50% and 10% were obtained for the densimeter scale respectively. A reproducibility analysis of the method was performed with satisfactory results. Different suppliers were contacted to estimate the economic costs of the equipment and materials, needed to develop the documented method of densimeter calibration. The acquisition of an analytical balance was recommended, instead of a precision scale, in order to improve the results obtained with the documented method [es

Light polarization management via reflection from arrays of sub-wavelength metallic twisted bands

Science.gov (United States)

Nawrot, M.; Haberko, J.; Zinkiewicz, Ł.; Wasylczyk, P.

2017-12-01

With constant progress of nano- and microfabrication technologies, photolithography in particular, a number of sub-wavelength metallic structures have been demonstrated that can be used to manipulate light polarization. Numerical simulations of light propagation hint that helical twisted bands can have interesting polarization properties. We use three-dimensional two-photon photolithography (direct laser writing) to fabricate a few-micrometer-thick arrays of twisted bands and coat them uniformly with metal. We demonstrate that circular polarization can be generated from linear polarization upon reflection from such structures over a broad range of frequencies in the mid infrared.

Calibration technique and study on metrological characteristics of a high-voltage inverse square-law function generator

International Nuclear Information System (INIS)

Popov, V.P.; Semenov, A.L.

1987-01-01

The calibration technique is described, and the metrological characteristics of a high-voltage generator of the inverse-quadratic function (HGF), being a functional unit of the diagnostic system of an electrodynamic analyser of a ionic component of a laser plasma, is analysed. The results of HGF testing in the range of time constants of the τ=(5-25)μs function are given. Analysis of metrologic and experimental characteristics shows, that HGF with automatic calibration has quite high accurate parameters. The high accuracy of function generation is provided with the possibility of calibration and adjustment conduction under experimental working conditions. Increase of the generated pulse amplitude to several tens of kilovelts is possible. Besides, the possibility of timely function adjustment to the necessary parameter (τ) increases essentially the HGF functional possibilities

Preliminary Results of BTDF Calibration of Transmissive Solar Diffusers for Remote Sensing

Science.gov (United States)

Georgiev, Georgi T.; Butler, James J.; Thome, Kurt; Cooksey, Catherine; Ding, Leibo

2016-01-01

Satellite instruments operating in the reflected solar wavelength region require accurate and precise determination of the optical properties of their diffusers used in pre-flight and post-flight calibrations. The majority of recent and current space instruments use reflective diffusers. As a result, numerous Bidirectional Reflectance Distribution Function (BRDF) calibration comparisons have been conducted between the National Institute of Standards and Technology (NIST) and other industry and university-based metrology laboratories. However, based on literature searches and communications with NIST and other laboratories, no Bidirectional Transmittance Distribution Function (BTDF) measurement comparisons have been conducted between National Measurement Laboratories (NMLs) and other metrology laboratories. On the other hand, there is a growing interest in the use of transmissive diffusers in the calibration of satellite, air-borne, and ground-based remote sensing instruments. Current remote sensing instruments employing transmissive diffusers include the Ozone Mapping and Profiler Suite instrument (OMPS) Limb instrument on the Suomi-National Polar-orbiting Partnership (S-NPP) platform,, the Geostationary Ocean Color Imager (GOCI) on the Korea Aerospace Research Institute's (KARI) Communication, Ocean, and Meteorological Satellite (COMS), the Ozone Monitoring Instrument (OMI) on NASA's Earth Observing System (EOS) Aura platform, the Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument and the Geostationary Environmental Monitoring Spectrometer (GEMS).. This ensemble of instruments requires validated BTDF measurements of their on-board transmissive diffusers from the ultraviolet through the near infrared. This paper presents the preliminary results of a BTDF comparison between the NASA Diffuser Calibration Laboratory (DCL) and NIST on quartz and thin Spectralon samples.

Preliminary results of BTDF calibration of transmissive solar diffusers for remote sensing

Science.gov (United States)

Georgiev, Georgi T.; Butler, James J.; Thome, Kurt; Cooksey, Catherine; Ding, Leibo

2016-09-01

Satellite instruments operating in the reflected solar wavelength region require accurate and precise determination of the optical properties of their diffusers used in pre-flight and post-flight calibrations. The majority of recent and current space instruments use reflective diffusers. As a result, numerous Bidirectional Reflectance Distribution Function (BRDF) calibration comparisons have been conducted between the National Institute of Standards and Technology (NIST) and other industry and university-based metrology laboratories. However, based on literature searches and communications with NIST and other laboratories, no Bidirectional Transmittance Distribution Function (BTDF) measurement comparisons have been conducted between National Measurement Laboratories (NMLs) and other metrology laboratories. On the other hand, there is a growing interest in the use of transmissive diffusers in the calibration of satellite, air-borne, and ground-based remote sensing instruments. Current remote sensing instruments employing transmissive diffusers include the Ozone Mapping and Profiler Suite instrument (OMPS) Limb instrument on the Suomi-National Polar-orbiting Partnership (S-NPP) platform,, the Geostationary Ocean Color Imager (GOCI) on the Korea Aerospace Research Institute's (KARI) Communication, Ocean, and Meteorological Satellite (COMS), the Ozone Monitoring Instrument (OMI) on NASA's Earth Observing System (EOS) Aura platform, the Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument and the Geostationary Environmental Monitoring Spectrometer (GEMS).. This ensemble of instruments requires validated BTDF measurements of their onboard transmissive diffusers from the ultraviolet through the near infrared. This paper presents the preliminary results of a BTDF comparison between the NASA Diffuser Calibration Laboratory (DCL) and NIST on quartz and thin Spectralon samples.

The Monitoring and Calibration Web Systems for the ATLAS Tile Calorimeter Data Quality Analysis

International Nuclear Information System (INIS)

Sivolella, A; Maidantchik, C; Ferreira, F

2012-01-01

The Tile Calorimeter (TileCal) is one of the ATLAS sub-detectors. The read-out is performed by about 10,000 PhotoMultiplier Tubes (PMTs). The signal of each PMT is digitized by an electronic channel. The Monitoring and Calibration Web System (MCWS) supports the data quality analysis of the electronic channels. This application was developed to assess the detector status and verify its performance. It can provide to the user the list of TileCal known problematic channels, that is stored in the ATLAS condition database (COOL DB). The bad channels list guides the data quality validator in identifying new problematic channels and is used in data reconstruction and the system allows to update the channels list directly in the COOL database. MCWS can generate summary results, such as eta-phi plots and comparative tables of the masked channels percentage. Regularly, during the LHC (Large Hadron Collider) shutdown a maintenance of the detector equipments is performed. When a channel is repaired, its calibration constants stored in the COOL database have to be updated. Additionally MCWS system manages the update of these calibration constants values in the COOL database. The MCWS has been used by the Tile community since 2008, during the commissioning phase, and was upgraded to comply with ATLAS operation specifications. Among its future developments, it is foreseen an integration of MCWS with the TileCal control Web system (DCS) in order to identify high voltage problems automatically.

PROSPECTING IN LATE-TYPE DWARFS: A CALIBRATION OF INFRARED AND VISIBLE SPECTROSCOPIC METALLICITIES OF LATE K AND M DWARFS SPANNING 1.5 dex

Energy Technology Data Exchange (ETDEWEB)

Mann, Andrew W.; Hilton, Eric J. [Institute for Astronomy, University of Hawai' i, 2680 Woodlawn Dr, Honolulu, HI 96822 (United States); Brewer, John M. [Department of Astronomy, Yale University, New Haven, CT 06511 (United States); Gaidos, Eric [Department of Geology and Geophysics, University of Hawai' i, 1680 East-West Road, Honolulu, HI 96822 (United States); Lepine, Sebastien [Department of Astrophysics, American Museum of Natural History, New York, NY 10024 (United States)

2013-02-01

Knowledge of late K and M dwarf metallicities can be used to guide planet searches and constrain planet formation models. However, the determination of metallicities of late-type stars is difficult because visible wavelength spectra of their cool atmospheres contain many overlapping absorption lines, preventing the measurement of equivalent widths. We present new methods, and improved calibrations of existing methods, to determine metallicities of late K and M dwarfs from moderate resolution (1300 < R < 2000) visible and infrared spectra. We select a sample of 112 wide binary systems that contain a late-type companion to a solar-type primary star. Our sample includes 62 primary stars with previously published metallicities, as well as 50 stars with metallicities determined from our own observations. We use our sample to empirically determine which features in the spectrum of the companion are best correlated with the metallicity of the primary. We find {approx_equal}120 features in K and M dwarf spectra that are useful for predicting metallicity. We derive metallicity calibrations for different wavelength ranges, and show that it is possible to get metallicities reliable to <0.10 dex using either visible, J-, H-, or K-band spectra. We find that the most accurate metallicities derived from visible spectra requires the use of different calibrations for early-type (K5.5-M2) and late-type (M2-M6) dwarfs. Our calibrations are applicable to dwarfs with metallicities of -1.04 < [Fe/H] <+0.56 and spectral types from K7 to M5. Lastly, we use our sample of wide binaries to test and refine existing calibrations to determine M dwarf metallicities. We find that the {zeta} parameter, which measures the ratio of TiO can CaH bands, is correlated with [Fe/H] for super-solar metallicities, and {zeta} does not always correctly identify metal-poor M dwarfs. We also find that existing calibrations in the K and H bands are quite reliable for stars with [Fe/H] >-0.5, but are less useful

The S-NPP VIIRS Day-Night Band On-Orbit Calibration/Characterization and Current State of SDR Products

Directory of Open Access Journals (Sweden)

Shihyan Lee

2014-12-01

Full Text Available The launch of VIIRS on-board the Suomi-National Polar-orbiting Partnership (S-NPP on 28 October 2011, marked the beginning of the next chapter on nighttime lights observation started by the Defense Meteorological Satellite Program’s (DMSP OLS sensor more than two decades ago. The VIIRS observes the nighttime lights on Earth through its day-night band (DNB, a panchromatic channel covering the wavelengths from 500 nm to 900 nm. Compared to its predecessors, the VIIRS DNB has a much improved spatial/temporal resolution, radiometric sensitivity and, more importantly, continuous calibration using on-board calibrators (OBCs. In this paper, we describe the current state of the NASA calibration and characterization methodology used in supporting mission data quality assurance and producing consistent mission-wide sensor data records (SDRs through NASA’s Land Product Evaluation and Analysis Tool Element (Land PEATE. The NASA calibration method utilizes the OBCs to determine gains, offset drift and sign-to-noise ratio (SNR over the entire mission. In gain determination, the time-dependent relative spectral response (RSR is used to correct the optical throughput change over time. A deep space view acquired during an S-NPP pitch maneuver is used to compute the airglow free dark offset for DNB’s high gain stage. The DNB stray light is estimated each month from new-moon dark Earth surface observations to remove the excessive stray light over the day-night terminators. As the VIIRS DNB on-orbit calibration is the first of its kind, the evolution of the calibration methodology is evident when the S-NPP VIIRS’s official calibrations are compared with our latest mission-wide reprocessing. In the future, the DNB calibration methodology is likely to continue evolving, and the mission-wide reprocessing is a key to providing consistently calibrated DNB SDRs for the user community. In the meantime, the NASA Land PEATE provides an alternative source to obtain

Compactly packaged monolithic four-wavelength VCSEL array with 100-GHz wavelength spacing for future-proof mobile fronthaul transport.

Science.gov (United States)

Lee, Eun-Gu; Mun, Sil-Gu; Lee, Sang Soo; Lee, Jyung Chan; Lee, Jong Hyun

2015-01-12

We report a cost-effective transmitter optical sub-assembly using a monolithic four-wavelength vertical-cavity surface-emitting laser (VCSEL) array with 100-GHz wavelength spacing for future-proof mobile fronthaul transport using the data rate of common public radio interface option 6. The wavelength spacing is achieved using selectively etched cavity control layers and fine current adjustment. The differences in operating current and output power for maintaining the wavelength spacing of four VCSELs are fiber without any dispersion-compensation techniques.

Development and operational performance of a single calibration chamber for radon detectors

International Nuclear Information System (INIS)

Lopez-Coto, I.; Bolivar, J.P.; Mas, J.L.; Garcia-Tenorio, R.; Vargas, A.

2007-01-01

This work shows the design, setup and performance of a new single radon detector calibration chamber developed at the University of Huelva (Environmental Radioactivity Group). This system is based on a certified radon source and a traceable reference radon detector, which allows radon concentrations inside the chamber radon to be obtained in steady-state conditions within a range of 400-22 000 Bq m -3 with associated uncertainties in the range of 4%. In addition, the development of a new ad hoc calibration protocol (UHU-RC/01/06 'Rachel'), which is based on the modelling of radon concentration within the chamber, allows it to be used without the reference detector. To do that, a complete characterization and calibration of the different leakage constants and the flow meter reading have been performed. The accuracy and general performance of both working methods for the same chamber (i.e., with and without the reference detector) have been tested by means of their participation in an intercomparison exercise involving five active radon monitors

Calibration of the hadronic calorimeter prototype for a future lepton collider

Energy Technology Data Exchange (ETDEWEB)

Schroeder, Sarah; Garutti, Erika [Institute for Experimental Physics, Hamburg University, Luruper Chaussee 149, D-22761 Hamburg (Germany); Collaboration: CALICE-D-Collaboration

2016-07-01

The CALICE AHCAL technological prototype is a hadronic calorimeter prototype for a future e{sup +}e{sup -} - collider. It is designed as a sampling calorimeter alternating steel absorber plates and active readout layers, segmented in single plastic scintillator tiles of 3 x 3 x 0.3 cm{sup 3} volume. Each tile is individually coupled to a silicon photomultiplier, read out by a dedicated ASIC with energy measurement and time stamping capability. The high granularity is meant to enable imaging and separation of single showers, for a Particle Flow approach to the jet energy measurement. The prototype aims to establish a scalable solution for an ILC detector. A total of 3456 calorimeter cells need to be inter-calibrated, for this the response to muons is used. The calibration procedure is presented, and the statistic and systematic uncertainties are discussed, which have a direct impact on the constant term of the calorimeter energy resolution. Additionally, the MIP yield in number of fired SiPM pixels can be compared betw een the muon calibration and a test bench calibrations obtained using a Sr sourc e on the single tiles before the assembly of the calorimeter. A good correlation would enable pre-calibation of the single channels on the test bench to be port able to the assemble detector. This hypothesis is checked with the present work.

AWG Filter for Wavelength Interrogator

Science.gov (United States)

Black, Richard J. (Inventor); Costa, Joannes M. (Inventor); Faridian, Fereydoun (Inventor); Moslehi, Behzad (Inventor); Sotoudeh, Vahid (Inventor)

2015-01-01

A wavelength interrogator is coupled to a circulator which couples optical energy from a broadband source to an optical fiber having a plurality of sensors, each sensor reflecting optical energy at a unique wavelength and directing the reflected optical energy to an AWG. The AWG has a detector coupled to each output, and the reflected optical energy from each grating is coupled to the skirt edge response of the AWG such that the adjacent channel responses form a complementary pair response. The complementary pair response is used to convert an AWG skirt response to a wavelength.

A Consistent EPIC Visible Channel Calibration Using VIIRS and MODIS as a Reference.

Science.gov (United States)

Haney, C.; Doelling, D. R.; Minnis, P.; Bhatt, R.; Scarino, B. R.; Gopalan, A.

2017-12-01

The Earth Polychromatic Imaging Camera (EPIC) aboard the Deep Space Climate Observatory (DSCOVR) satellite constantly images the sunlit disk of Earth from the Lagrange-1 (L1) point in 10 spectral channels spanning the UV, VIS, and NIR spectrums. Recently, the DSCOVR EPIC team has publicly released version 2 dataset, which has implemented improved navigation, stray-light correction, and flat-fielding of the CCD array. The EPIC 2-year data record must be well-calibrated for consistent cloud, aerosol, trace gas, land use and other retrievals. Because EPIC lacks onboard calibrators, the observations made by EPIC channels must be calibrated vicariously using the coincident measurements from radiometrically stable instruments that have onboard calibration systems. MODIS and VIIRS are best-suited instruments for this task as they contain similar spectral bands that are well-calibrated onboard using solar diffusers and lunar tracking. We have previously calibrated the EPIC version 1 dataset by using EPIC and VIIRS angularly matched radiance pairs over both all-sky ocean and deep convective clouds (DCC). We noted that the EPIC image required navigations adjustments, and that the EPIC stray-light correction provided an offset term closer to zero based on the linear regression of the EPIC and VIIRS ray-matched radiance pairs. We will evaluate the EPIC version 2 navigation and stray-light improvements using the same techniques. In addition, we will monitor the EPIC channel calibration over the two years for any temporal degradation or anomalous behavior. These two calibration methods will be further validated using desert and DCC invariant Earth targets. The radiometric characterization of the selected invariant targets is performed using multiple years of MODIS and VIIRS measurements. Results of these studies will be shown at the conference.

ORNL calibrations facility

International Nuclear Information System (INIS)

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

Absolute sensitivity calibration from 20 A to 430 A of a grazing incidence spectrometer with a multi-element spectral detector

International Nuclear Information System (INIS)

Terry, J.L.; Manning, H.L.; Marmar, E.S.

1986-07-01

Two methods which together allow sensitivity calibration from 20 A to 430 A are described in detail. The first method, useful up to 120 A, uses a low power source to generate Kα x-rays which are alternately viewed by an absolute detector (a proportional counter) and the spectrometer. The second method extends that calibration to 430 A. It relies on the 2:1 brightness ratio of bright doublet lines from impurity ions which have a single outer shell electron and which are present in hot, magnetically confined plasmas. It requires that the absolute sensitivity of the spectrometer be known at one wavelength point, and in practice requires a multi-element spectral detector

Passively synchronized dual-wavelength Q-switched lasers

DEFF Research Database (Denmark)

Janousek, Jiri; Tidemand-Lichtenberg, Peter; Mortensen, Jesper Liltorp

We present a simple and efficient way of generating synchronized Q-switched pulses at wavelengths hundreds of nanometers apart. This principle can result in new pulsed all-solid-state light sources at new wavelengths based on SFG.......We present a simple and efficient way of generating synchronized Q-switched pulses at wavelengths hundreds of nanometers apart. This principle can result in new pulsed all-solid-state light sources at new wavelengths based on SFG....

CALIBRATION ERRORS IN THE CAVITY BEAM POSITION MONITOR SYSTEM AT THE ATF2

CERN Document Server

Cullinan, F; Joshi, N; Lyapin, A

2011-01-01

It has been shown at the Accelerator Test Facility at KEK, that it is possible to run a system of 37 cavity beam position monitors (BPMs) and achieve high working resolution. However, stability of the calibration constants (position scale and radio frequency (RF) phase) over a three/four week running period is yet to be demonstrated. During the calibration procedure, random beam jitter gives rise to a statistical error in the position scale and slow orbit drift in position and tilt causes systematic errors in both the position scale and RF phase. These errors are dominant and have been evaluated for each BPM. The results are compared with the errors expected after a tested method of beam jitter subtraction has been applied.

Calibration Efforts and Unique Capabilities of the HST Space Telescope Imaging Spectrograph

Science.gov (United States)

Monroe, TalaWanda R.; Proffitt, Charles R.; Welty, Daniel; Branton, Doug; Carlberg, Joleen K.; debes, John Henry; Lockwood, Sean; Riley, Allyssa; Sohn, Sangmo Tony; Sonnentrucker, Paule G.; Walborn, Nolan R.; Jedrzejewski, Robert I.

2018-01-01

The Space Telescope Imaging Spectrograph (STIS) continues to offer the astronomy community the ability to carry out innovative UV and optical spectroscopic and imaging studies, two decades after its deployment on the Hubble Space Telescope (HST). Most notably, STIS provides spectroscopy in the FUV and NUV, including high spectral resolution echelle modes, imaging in the FUV, optical spectroscopy, and coronagraphic capabilities. Additionally, spatial scanning on the CCD with the long-slits is now possible to enable very high S/N spectroscopic observations without saturation while mitigating telluric and fringing concerns in the far red and near-IR. This new mode may especially benefit the diffuse interstellar bands and exoplanet transiting communities. We present recent calibration efforts for the instrument, including work to optimize the calibration of the echelle spectroscopic modes by improving the flux agreement of overlapping spectral orders affected by changes in the grating blaze function since HST Servicing Mission 4. We also discuss considerations to maintain the wavelength precision of the spectroscopic modes, and the current capabilities of CCD spectroscopic spatial trails.

SCIAMACHY Level 1 data: calibration concept and in-flight calibration

Science.gov (United States)

Lichtenberg, G.; Kleipool, Q.; Krijger, J. M.; van Soest, G.; van Hees, R.; Tilstra, L. G.; Acarreta, J. R.; Aben, I.; Ahlers, B.; Bovensmann, H.; Chance, K.; Gloudemans, A. M. S.; Hoogeveen, R. W. M.; Jongma, R. T. N.; Noël, S.; Piters, A.; Schrijver, H.; Schrijvers, C.; Sioris, C. E.; Skupin, J.; Slijkhuis, S.; Stammes, P.; Wuttke, M.

2006-11-01

The calibration of SCIAMACHY was thoroughly checked since the instrument was launched on-board ENVISAT in February 2002. While SCIAMACHY's functional performance is excellent since launch, a number of technical difficulties have appeared, that required adjustments to the calibration. The problems can be separated into three types: (1) Those caused by the instrument and/or platform environment. Among these are the high water content in the satellite structure and/or MLI layer. This results in the deposition of ice on the detectors in channels 7 and 8 which seriously affects the retrievals in the IR, mostly because of the continuous change of the slit function caused by scattering of the light through the ice layer. Additionally a light leak in channel 7 severely hampers any retrieval from this channel. (2) Problems due to errors in the on-ground calibration and/or data processing affecting for example the radiometric calibration. A new approach based on a mixture of on-ground and in-flight data is shortly described here. (3) Problems caused by principal limitations of the calibration concept, e.g. the possible appearance of spectral structures after the polarisation correction due to unavoidable errors in the determination of atmospheric polarisation. In this paper we give a complete overview of the calibration and problems that still have to be solved. We will also give an indication of the effect of calibration problems on retrievals where possible. Since the operational processing chain is currently being updated and no newly processed data are available at this point in time, for some calibration issues only a rough estimate of the effect on Level 2 products can be given. However, it is the intention of this paper to serve as a future reference for detailed studies into specific calibration issues.

Effect of plastic deformation and strain history on X-ray elastic constants

International Nuclear Information System (INIS)

Iadicola, Mark A.; Foecke, Tim

2005-01-01

The use of X-ray diffraction to measure residual stress in a crystalline material is well known. This method is currently being reapplied to the surface measurement of in situ stresses during biaxial straining of sheet metal specimens. This leads to questions of precision and calibration of the method through plastic deformation. Little is known of the change, with plastic work, in the X-ray elastic constants (XECs) that are required by the technique for stress measurement. Experiments to determine the formability of various materials using this stress measurement technique in conjunction with a typical Marciniak test (with the Raghavan variation of specimen shapes) have been performed assuming a constant value for XECs. New results of calibration experiments are presented which admit the possibility of variation of the XECs with plastic strain history and initial texture of the material. Adjustment of the data from the previously performed formability experiments is shown. Additionally, various phenomena are captured including initial yielding, change of XECs with plastic strain level (both with uniaxial and biaxial strain histories), and some of the effects of texture on the technique. This technique has potential application in verification of the assumptions made during other standard testing methods (in-plane biaxial specimen geometries and bulge testing), verifying stress predictions from finite element analyses (i.e. benchmarking experiments such as BM3), analysis of stress states in localized deformation (yield point effects), and tracking of the effect of prestraining on material formability through the process of multistage forming

Status of ionization chambers calibration for radiation therapy in Brazil

Science.gov (United States)

Gonçalves, M.; Joana, G.; Leal, P.; Vasconcelos, R.; do Couto, N.; Teixeira, F. C.; Soares, A. D.; Santini, E. S.; Salata, C.

2018-03-01

CNEN makes a constant effort to keep updated with international standards and national needs to strengthen the radiological protection status of the country. The guidelines related to radiation treatment facilities have been revised in the last five years in order to take in consideration the most relevant aspects of the growing technology as well as to mitigate the accidents or incidents observed in practice. Hence, clinical dosimeters have gained special importance as significant items in Brazilian regulation. In the present work we discuss the importance of inspections from the point of view of equipment dosimetry and instruments quality control. The dosimeter sets based on thimble and well ionization chambers need periodic calibration, and this calibration becomes a fundamental task in order to guarantee the dose prescribed-delivered to patients. Thus Brazilian guidelines enforce the need of at least two sets of clinical dosimeters with thimble chambers calibrated and one set of electrometer with well ionization chamber for hdr equipment. We call attention to the fact that inspections are a very valuable tool in order to enforce the application of guidelines around the country both by enlightening the weaker aspects of facilities concerning radiological protection and by stating in loco that reasons which lead the regulatory body to enforce such guidelines items.

Spitzer/JWST Cross Calibration: IRAC Observations of Potential Calibrators for JWST

Science.gov (United States)

Carey, Sean J.; Gordon, Karl D.; Lowrance, Patrick; Ingalls, James G.; Glaccum, William J.; Grillmair, Carl J.; E Krick, Jessica; Laine, Seppo J.; Fazio, Giovanni G.; Hora, Joseph L.; Bohlin, Ralph

2017-06-01

We present observations at 3.6 and 4.5 microns using IRAC on the Spitzer Space Telescope of a set of main sequence A stars and white dwarfs that are potential calibrators across the JWST instrument suite. The stars range from brightnesses of 4.4 to 15 mag in K band. The calibration observations use a similar redundancy to the observing strategy for the IRAC primary calibrators (Reach et al. 2005) and the photometry is obtained using identical methods and instrumental photometric corrections as those applied to the IRAC primary calibrators (Carey et al. 2009). The resulting photometry is then compared to the predictions based on spectra from the CALSPEC Calibration Database (http://www.stsci.edu/hst/observatory/crds/calspec.html) and the IRAC bandpasses. These observations are part of an ongoing collaboration between IPAC and STScI investigating absolute calibration in the infrared.

Bayesian Estimation of the Active Concentration and Affinity Constants Using Surface Plasmon Resonance Technology.

Directory of Open Access Journals (Sweden)

Feng Feng

Full Text Available Surface plasmon resonance (SPR has previously been employed to measure the active concentration of analyte in addition to the kinetic rate constants in molecular binding reactions. Those approaches, however, have a few restrictions. In this work, a Bayesian approach is developed to determine both active concentration and affinity constants using SPR technology. With the appropriate prior probabilities on the parameters and a derived likelihood function, a Markov Chain Monte Carlo (MCMC algorithm is applied to compute the posterior probability densities of both the active concentration and kinetic rate constants based on the collected SPR data. Compared with previous approaches, ours exploits information from the duration of the process in its entirety, including both association and dissociation phases, under partial mass transport conditions; do not depend on calibration data; multiple injections of analyte at varying flow rates are not necessary. Finally the method is validated by analyzing both simulated and experimental datasets. A software package implementing our approach is developed with a user-friendly interface and made freely available.

Energy Levels, wavelengths and hyperfine structure measurements of Sc II

Science.gov (United States)

Hala, Fnu; Nave, Gillian

2018-01-01

Lines of singly ionized Scandium (Sc II) along with other Iron group elements have been observed [1] in the region surrounding the massive star Eta Carinae [2,3] called the strontium filament (SrF). The last extensive analysis of Sc II was the four-decade old work of Johansson & Litzen [4], using low-resolution grating spectroscopy. To update and extend the Sc II spectra, we have made observation of Sc/Ar, Sc/Ne and Sc/Ge/Ar hollow cathode emission spectrum on the NIST high resolution FT700 UV/Vis and 2 m UV/Vis/IR Fourier transform spectrometers (FTS). More than 850 Sc II lines have been measured in the wavelength range of 187 nm to 3.2 μm. connecting a total of 152 energy levels. The present work also focuses to resolve hyperfine structure (HFS) in Sc II lines. We aim to obtain accurate transition wavelengths, improved energy levels and HFS constants of Sc II. The latest results from work in progress will be presented.Reference[1] Hartman H, Gull T, Johansson S and Smith N 2004 Astron. Astrophys. 419 215[2] Smith N, Morse J A and Gull T R 2004 Astrophys. J. 605 405[3] Davidson K and Humphreys R M 1997 Annu. Rev. Astron. Astrophys. 35[4] Johansson S and Litzén U 1980 Phys. Scr. 22 49

Potential constants and centrifugal distortion constants of octahedral hexafluoride molecules

Energy Technology Data Exchange (ETDEWEB)

Manivannan, G [Government Thirumagal Mill' s Coll., Gudiyattam, Tamil Nadu (India)

1981-04-01

The kinetic constants method outlined by Thirugnanasambandham (1964) based on Wilson's (1955) group theory has been adapted in evaluating the potential constants for SF/sub 6/, SeF/sub 6/, WF/sub 6/, IrF/sub 6/, UF/sub 6/, NpF/sub 6/, and PuF/sub 6/ using the experimentally observed vibrational frequency data. These constants are used to calculate the centrifugal distortion constants for the first time.

Simultaneous calibration phantom commission and geometry calibration in cone beam CT

Science.gov (United States)

Xu, Yuan; Yang, Shuai; Ma, Jianhui; Li, Bin; Wu, Shuyu; Qi, Hongliang; Zhou, Linghong

2017-09-01

Geometry calibration is a vital step for describing the geometry of a cone beam computed tomography (CBCT) system and is a prerequisite for CBCT reconstruction. In current methods, calibration phantom commission and geometry calibration are divided into two independent tasks. Small errors in ball-bearing (BB) positioning in the phantom-making step will severely degrade the quality of phantom calibration. To solve this problem, we propose an integrated method to simultaneously realize geometry phantom commission and geometry calibration. Instead of assuming the accuracy of the geometry phantom, the integrated method considers BB centers in the phantom as an optimized parameter in the workflow. Specifically, an evaluation phantom and the corresponding evaluation contrast index are used to evaluate geometry artifacts for optimizing the BB coordinates in the geometry phantom. After utilizing particle swarm optimization, the CBCT geometry and BB coordinates in the geometry phantom are calibrated accurately and are then directly used for the next geometry calibration task in other CBCT systems. To evaluate the proposed method, both qualitative and quantitative studies were performed on simulated and realistic CBCT data. The spatial resolution of reconstructed images using dental CBCT can reach up to 15 line pair cm-1. The proposed method is also superior to the Wiesent method in experiments. This paper shows that the proposed method is attractive for simultaneous and accurate geometry phantom commission and geometry calibration.

SPRT Calibration Uncertainties and Internal Quality Control at a Commercial SPRT Calibration Facility

Science.gov (United States)

Wiandt, T. J.

2008-06-01

The Hart Scientific Division of the Fluke Corporation operates two accredited standard platinum resistance thermometer (SPRT) calibration facilities, one at the Hart Scientific factory in Utah, USA, and the other at a service facility in Norwich, UK. The US facility is accredited through National Voluntary Laboratory Accreditation Program (NVLAP), and the UK facility is accredited through UKAS. Both provide SPRT calibrations using similar equipment and procedures, and at similar levels of uncertainty. These uncertainties are among the lowest available commercially. To achieve and maintain low uncertainties, it is required that the calibration procedures be thorough and optimized. However, to minimize customer downtime, it is also important that the instruments be calibrated in a timely manner and returned to the customer. Consequently, subjecting the instrument to repeated calibrations or extensive repeated measurements is not a viable approach. Additionally, these laboratories provide SPRT calibration services involving a wide variety of SPRT designs. These designs behave differently, yet predictably, when subjected to calibration measurements. To this end, an evaluation strategy involving both statistical process control and internal consistency measures is utilized to provide confidence in both the instrument calibration and the calibration process. This article describes the calibration facilities, procedure, uncertainty analysis, and internal quality assurance measures employed in the calibration of SPRTs. Data will be reviewed and generalities will be presented. Finally, challenges and considerations for future improvements will be discussed.

Calibration of the DSCOVR EPIC Visible and NIR Channels using MODIS Terra and Aqua Data and EPIC Lunar Observations

Science.gov (United States)

Geogdzhayev, Igor V.; Marshak, Alexander

2018-01-01

The unique position of the Deep Space Climate Observatory (DSCOVR) Earth Polychromatic Imaging Camera (EPIC) at the Lagrange 1 point makes an important addition to the data from currently operating low Earth orbit observing instruments. EPIC instrument does not have an onboard calibration facility. One approach to its calibration is to compare EPIC observations to the measurements from polar-orbiting radiometers. Moderate Resolution Imaging Spectroradiometer (MODIS) is a natural choice for such comparison due to its well-established calibration record and wide use in remote sensing. We use MODIS Aqua and Terra L1B 1km reflectances to infer calibration coefficients for four EPIC visible and NIR channels: 443, 551, 680 and 780 nm. MODIS and EPIC measurements made between June 2015 and 2016 are employed for comparison. We first identify favorable MODIS pixels with scattering angle matching temporarily collocated EPIC observations. Each EPIC pixel is then spatially collocated to a subset of the favorable MODIS pixels within 25 km radius. Standard deviation of the selected MODIS pixels as well as of the adjacent EPIC pixels is used to find the most homogeneous scenes. These scenes are then used to determine calibration coefficients using a linear regression between EPIC counts/sec and reflectances in the close MODIS spectral channels. We present thus inferred EPIC calibration coefficients and discuss sources of uncertainties. The lunar EPIC observations are used to calibrate EPIC O2 absorbing channels (688 and 764 nm), assuming that there is a small difference between moon reflectances separated by approx.10 nm in wavelength provided the calibration factors of the red (680 nm) and near-IR (780 nm) are known from comparison between EPIC and MODIS.

Short wavelength FELs using the SLAC linac

International Nuclear Information System (INIS)

Winick, H.; Bane, K.; Boyce, R.

1993-08-01

Recent technological developments have opened the possibility to construct a device which we call a Linac Coherent Light Source (LCLS); a fourth generation light source, with brightness, coherence, and peak power far exceeding other sources. Operating on the principle of the free electron laser (FEL), the LCLS would extend the range of FEL operation to much aborter wavelength than the 240 mn that has so far been reached. We report the results of studies of the use of the SLAC linac to drive an LCLS at wavelengths from about 3-100 nm initially and possibly even shorter wavelengths in the future. Lasing would be achieved in a single pass of a low emittance, high peak current, high energy electron beam through a long undulator. Most present FELs use an optical cavity to build up the intensity of the light to achieve lasing action in a low gain oscillator configuration. By eliminating the optical cavity, which is difficult to make at short wavelengths, laser action can be extended to shorter wavelengths by Self-Amplified-Spontaneous-Emission (SASE), or by harmonic generation from a longer wavelength seed laser. Short wavelength, single pass lasers have been extensively studied at several laboratories and at recent workshops

Mechanics of log calibration

International Nuclear Information System (INIS)

Waller, W.C.; Cram, M.E.; Hall, J.E.

1975-01-01

For any measurement to have meaning, it must be related to generally accepted standard units by a valid and specified system of comparison. To calibrate well-logging tools, sensing systems are designed which produce consistent and repeatable indications over the range for which the tool was intended. The basics of calibration theory, procedures, and calibration record presentations are reviewed. Calibrations for induction, electrical, radioactivity, and sonic logging tools will be discussed. The authors' intent is to provide an understanding of the sources of errors, of the way errors are minimized in the calibration process, and of the significance of changes in recorded calibration data

Precise Wavelengths and Energy Levels for the Spectra of Cr I, Mn I, and Mn III, and Branching Fractions for the Spectra of Fe II and Cr II

Science.gov (United States)

Nave, Gillian

I propose to measure wavelengths and energy levels for the spectra of Cr I, Mn I, and Mn III covering the wavelength range 80 nm to 5500 nm, and oscillator strengths for Fe II and Cr II in the region 120 nm to 2500 nm. I shall also produce intensity calibrated atlases and linelists of the iron-neon and chromium-neon hollow cathode lamps that can be compared with astrophysical spectra. The spectra will be obtained from archival data from spectrometers at NIST and Kitt Peak National Observatory and additional experimental observations as necessary from Fourier transform (FT) and grating spectrometers at NIST. The wavelength uncertainty of the strong lines will be better than 1 part in 10^7. The radiometric calibration of the spectra will be improved in order to reduce the uncertainty of measured oscillator strengths in the near UV region and extend the wavelength range of these measurements down to 120 nm. These will complement and support the measurements of lifetimes and branching fractions by J. E. Lawler in the near UV region. An intensive effort by NIST and Imperial College London that was partly funded by previous NASA awards has resulted in comprehensive analyses of the spectra of Fe II, Cr II and Cu II, with similar analyses of Mn II, Ni II, and Sc II underway. The species included in this proposal will complete the analysis of the first two ionization stages of the elements titanium through nickel using the same techniques, and add the spectrum of Mn III - one of the most important doubly-ionized elements. The elements Cr I and Mn I give large numbers of spectral lines in spectra of cool stars and important absorption lines in the interstellar medium. The spectrum of Mn III is important in chemically peculiar stars and can often only be studied in the UV region. Analyses of many stellar spectra depend on comprehensive analyses of iron-group elements and are hampered by incomplete spectroscopic data. As a result of many decades of work by the group at the

Calibration of the Super-Kamiokande detector

Energy Technology Data Exchange (ETDEWEB)

Abe, K. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Gifu 506-1205 (Japan); Hayato, Y. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Gifu 506-1205 (Japan); Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Iida, T.; Iyogi, K.; Kameda, J. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Gifu 506-1205 (Japan); Kishimoto, Y. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Gifu 506-1205 (Japan); Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Koshio, Y., E-mail: koshio@fphy.hep.okayama-u.ac.jp [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Gifu 506-1205 (Japan); Marti, Ll.; Miura, M. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Gifu 506-1205 (Japan); Moriyama, S.; Nakahata, M. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Gifu 506-1205 (Japan); Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Nakano, Y.; Nakayama, S.; Obayashi, Y.; Sekiya, H. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Gifu 506-1205 (Japan); Shiozawa, M.; Suzuki, Y. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Gifu 506-1205 (Japan); Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Takeda, A.; Takenaga, Y.; Tanaka, H. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Gifu 506-1205 (Japan); and others

2014-02-11

Procedures and results on hardware-level detector calibration in Super-Kamiokande (SK) are presented in this paper. In particular, we report improvements made in our calibration methods for the experimental phase IV in which new readout electronics have been operating since 2008. The topics are separated into two parts. The first part describes the determination of constants needed to interpret the digitized output of our electronics so that we can obtain physical numbers such as photon counts and their arrival times for each photomultiplier tube (PMT). In this context, we developed an in situ procedure to determine high-voltage settings for PMTs in large detectors like SK, as well as a new method for measuring PMT quantum efficiency and gain in such a detector. The second part describes modeling of the detector in Monte Carlo simulations, including, in particular, the optical properties of the water target and their variability over time. Detailed studies on water quality are also presented. As a result of this work, we have achieved a precision sufficient for physics analyses over a wide energy range (from a few MeV to above 1 TeV). For example, charge determination was at the level of 1%, and the timing resolution was 2.1 ns at the one-photoelectron charge level and 0.5 ns at the 100-photoelectron charge level.

Sub-wavelength plasmon laser

Science.gov (United States)

Bora, Mihail; Bond, Tiziana C.

2016-04-19

A plasmonic laser device has resonant nanocavities filled with a gain medium containing an organic dye. The resonant plasmon frequencies of the nanocavities are tuned to align with both the absorption and emission spectra of the dye. Variables in the system include the nature of the dye and the wavelength of its absorption and emission, the wavelength of the pumping radiation, and the resonance frequencies of the nanocavities. In addition the pumping frequency of the dye is selected to be close to the absorption maximum.

The wavelength frame multiplication chopper system for the ESS test beamline at the BER II reactor—A concept study of a fundamental ESS instrument principle

International Nuclear Information System (INIS)

Strobl, M.; Bulat, M.; Habicht, K.

2013-01-01

Contributing to the design update phase of the European Spallation Source ESS–scheduled to start operation in 2019–a test beamline is under construction at the BER II research reactor at Helmholtz Zentrum Berlin (HZB). This beamline offers experimental test capabilities of instrument concepts viable for the ESS. The experiments envisaged at this dedicated beamline comprise testing of components as well as of novel experimental approaches and methods taking advantage of the long pulse characteristic of the ESS source. Therefore the test beamline will be equipped with a sophisticated chopper system that provides the specific time structure of the ESS and enables variable wavelength resolutions via wavelength frame multiplication (WFM), a fundamental instrument concept beneficial for a number of instruments at ESS. We describe the unique chopper system developed for these purposes, which allows constant wavelength resolution for a wide wavelength band. Furthermore we discuss the implications for the conceptual design for related instrumentation at the ESS

Scientific Impact of MODIS C5 Calibration Degradation and C6+ Improvements

Science.gov (United States)

Lyapustin, A.; Wang, Y.; Xiong, X.; Meister, G.; Platnick, S.; Levy, R.; Franz, B.; Korkin, S.; Hilker, T.; Tucker, J.;

STUDIES OF NGC 6720 WITH CALIBRATED HST/WFC3 EMISSION-LINE FILTER IMAGES. I. STRUCTURE AND EVOLUTION ,

International Nuclear Information System (INIS)

O'Dell, C. R.; Ferland, G. J.; Henney, W. J.; Peimbert, M.

2013-01-01

We have performed a detailed analysis of the Ring Nebula (NGC 6720) using Hubble Space Telescope WFC3 images and derived a new three-dimensional model. Existing high spectral resolution spectra played an important supplementary role in our modeling. It is shown that the Main Ring of the nebula is an ionization-bounded irregular non-symmetric disk with a central cavity and perpendicular extended lobes pointed almost toward the observer. The faint outer halos are determined to be fossil radiation, i.e., radiation from gas ionized in an earlier stage of the nebula when it was not ionization bounded. The narrowband WFC3 filters that isolate some of the emission lines are affected by broadening on their short wavelength side and all the filters were calibrated using ground-based spectra. The filter calibration results are presented in an appendix.

Analysis of subsystems in wavelength-division-multiplexing networks

DEFF Research Database (Denmark)

Liu, Fenghai

2001-01-01

Wavelength division multiplexing (WDM) technology together with optical amplification has created a new era for optical communication. Transmission capacity is greatly increased by adding more and more wavelength channels into a single fiber, as well as by increasing the line rate of each channel...... in semiconductor optical amplifiers (SOAs), and dispersion managed fiber sections. New subsystems are also proposed in the thesis: a modular 2×2 multiwavelength cross-connect using wavelength switching blocks, a wavelength converter based on cross phase modulation in a semiconductor modulator, a wavelength...

Shared robotic system: automated pipette calibration and pipette tip filter assembly

International Nuclear Information System (INIS)

Addison, J.H. Jr.; Dyches, G.M.

1985-01-01

At the Savannah River Laboratory a Zymate Laboratory Automation System has been developed to perform two completely independent tasks within one work cell. One operation is the precise calibration of pipettes; the other is the assembly of a filter in a pipette tip. Since neither task requires full robot time, the shared system is an economical means of robotizing both processes. These are tedious, repetitive, time consuming tasks; and human operators fail to yield constant results. Automation insures a repeatable process which increases product quality

Scanner calibration revisited

Directory of Open Access Journals (Sweden)

Pozhitkov Alexander E

2010-07-01

Full Text Available Abstract Background Calibration of a microarray scanner is critical for accurate interpretation of microarray results. Shi et al. (BMC Bioinformatics, 2005, 6, Art. No. S11 Suppl. 2. reported usage of a Full Moon BioSystems slide for calibration. Inspired by the Shi et al. work, we have calibrated microarray scanners in our previous research. We were puzzled however, that most of the signal intensities from a biological sample fell below the sensitivity threshold level determined by the calibration slide. This conundrum led us to re-investigate the quality of calibration provided by the Full Moon BioSystems slide as well as the accuracy of the analysis performed by Shi et al. Methods Signal intensities were recorded on three different microarray scanners at various photomultiplier gain levels using the same calibration slide from Full Moon BioSystems. Data analysis was conducted on raw signal intensities without normalization or transformation of any kind. Weighted least-squares method was used to fit the data. Results We found that initial analysis performed by Shi et al. did not take into account autofluorescence of the Full Moon BioSystems slide, which led to a grossly distorted microarray scanner response. Our analysis revealed that a power-law function, which is explicitly accounting for the slide autofluorescence, perfectly described a relationship between signal intensities and fluorophore quantities. Conclusions Microarray scanners respond in a much less distorted fashion than was reported by Shi et al. Full Moon BioSystems calibration slides are inadequate for performing calibration. We recommend against using these slides.

Correlation of retention of lanthanide and actinide complexes with stability constants and their speciation

Energy Technology Data Exchange (ETDEWEB)

Datta, A.; Sivaraman, N.; Viswanathan, K.S.; Ghosh, Suddhasattwa; Srinivasan, T.G.; Vasudeva Rao, P.R. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Chemistry Group

2013-03-01

The present study describes a correlation that is developed from retention of lanthanide and actinide complexes with the stability constant. In these studies, an ion-pairing reagent, camphor-10-sulphonic acid (CSA) was used as the modifier and organic acids such as {alpha}-hydroxy isobutyric acid ({alpha}-HIBA), mandelic acid, lactic acid and tartaric acid were used as complexing reagent for elution. From these studies, a correlation has been established between capacity factor of a metal ion, concentration of ion-pairing reagent and complexing agent with the stability constant of metal complex. Based on these studies, it has been shown that the stability constant of lanthanide and actinide complexes can be estimated using a single lanthanide calibrant. Validation of the method was carried out with the complexing agents such as {alpha}-HIBA and lactic acid. It was also demonstrated that data from a single chromatogram can be used for estimation of stability constant at various ionic strengths. These studies also demonstrated that the method can be applied for estimation of stability constant of actinides with a ligand whose value is not reported yet, e.g., ligands of importance in the lanthanide-actinide separations, chelation therapy etc. The chromatographic separation method is fast and the estimation of stability constant can be done in a very short time, which is a significant advantage especially in dealing with radioactive elements. The stability constant data was used to derive speciation data of plutonium in different oxidation states as well as that of americium with {alpha}-HIBA. The elution behavior of actinides such as Pu and Am from reversed phase chromatographic technique could be explained based on these studies. (orig.)

Characteristics of Viscoelastic Crustal Deformation Following a Megathrust Earthquake: Discrepancy Between the Apparent and Intrinsic Relaxation Time Constants

Science.gov (United States)

Fukahata, Yukitoshi; Matsu'ura, Mitsuhiro

2018-02-01

The viscoelastic deformation of an elastic-viscoelastic composite system is significantly different from that of a simple viscoelastic medium. Here, we show that complicated transient deformation due to viscoelastic stress relaxation after a megathrust earthquake can occur even in a very simple situation, in which an elastic surface layer (lithosphere) is underlain by a viscoelastic substratum (asthenosphere) under gravity. Although the overall decay rate of the system is controlled by the intrinsic relaxation time constant of the asthenosphere, the apparent decay time constant at each observation point is significantly different from place to place and generally much longer than the intrinsic relaxation time constant of the asthenosphere. It is also not rare that the sense of displacement rate is reversed during the viscoelastic relaxation. If we do not bear these points in mind, we may draw false conclusions from observed deformation data. Such complicated transient behavior can be explained mathematically from the characteristics of viscoelastic solution: for an elastic-viscoelastic layered half-space, the viscoelastic solution is expressed as superposition of three decaying components with different relaxation time constants that depend on wavelength.

Laboratory for the Dosimetric Equipment Calibration at the Institute of Nuclear Physics in Cracow

International Nuclear Information System (INIS)

Bilski, P.; Budzanowski, M.; Horwacik, T.; Marczewska, B.; Nowak, T.; Olko, P.; Ryba, E.; Zbroja, K.

2000-12-01

A new calibration laboratory has been developed at the INP, Cracow, Poland. The laboratory is located in a hall of dimension 9 m (length) x 4 m (wide) x 4.5 m (height). For calibration purposes the Cs-137 source of activity 185 MBq / 5 Ci / is applied, placed in the 16 cm thick lead capsule. The beam is collimated using a collimator with a constant opening of 20 o . The source is placed 2 m above the ground to avoid albedo scattering. This source covers a dose rate range from 17 mGy/h to 290 μGy/h. For low-dose calibration 0.05 Ci source is applied. The positioning of the source and opening of the collimator is pneumatically controlled. The dosimeters to be calibrated are placed onto a vehicle with DC motor positioned by PC computer. The vehicle is remotely positioned with the precision of one millimetre at the distance from the source between 1 and 7 meters. The vehicle positioning is controlled electronically and additionally checked via TV-camera. Exact dosimeter positioning is performed with a medical cross-laser and with a telescope device. The construction of the vehicle allows for performing of angular irradiations. On the axis of the vehicle 320 keV Phillips X-ray tube is installed which may be used as an irradiation source. UNIDOS dosimeter with PTW ionisation chambers is used for determination of the dose rate. This calibration stand is designed for calibration of personal dosimeters, calibration of active devices for radiation protections and for research on the newly developed thermoluminescent materials. (author)

The lick-index calibration of the Gemini multi-object spectrographs

International Nuclear Information System (INIS)

Puzia, Thomas H.; Miller, Bryan W.; Trancho, Gelys; Basarab, Brett; Mirocha, Jordan T.; Butler, Karen

2013-01-01

We present the calibration of the spectroscopic Lick/IDS standard line-index system for measurements obtained with the Gemini Multi-Object Spectrographs known as GMOS-North and GMOS-South. We provide linear correction functions for each of the 25 standard Lick line indices for the B600 grism and two instrumental setups, one with 0.''5 slit width and 1 × 1 CCD pixel binning (corresponding to ∼2.5 Å spectral resolution) and the other with 0.''75 slit width and 2 × 2 binning (∼4 Å). We find small and well-defined correction terms for the set of Balmer indices Hβ, Hγ A , and Hδ A along with the metallicity sensitive indices Fe5015, Fe5270, Fe5335, Fe5406, Mg 2 , and Mgb that are widely used for stellar population diagnostics of distant stellar systems. We find other indices that sample molecular absorption bands, such as TiO 1 and TiO 2 , with very wide wavelength coverage or indices that sample very weak molecular and atomic absorption features, such as Mg 1 , as well as indices with particularly narrow passband definitions, such as Fe4384, Ca4455, Fe4531, Ca4227, and Fe5782, which are less robustly calibrated. These indices should be used with caution.

Compact Optical Technique for Streak Camera Calibration

International Nuclear Information System (INIS)

Bell, P; Griffith, R; Hagans, K; Lerche, R; Allen, C; Davies, T; Janson, F; Justin, R; Marshall, B; Sweningsen, O

2004-01-01