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1

Skyshine spectra of gamma rays  

Microsoft Academic Search

A study of the spectra of gamma photons back-scattered in vertical direction by infinite air above ground (skyshine) is presented. The source for these measurements is a 650 Ci Cobalt-60 point-source and the skyshine spectra are reported for distances from 150 m to 325 m from the source, measured with a 5 cm NaI(T1) detector collimated with collimators of 12

J. Swarup

1980-01-01

2

GRABGAM Analysis of Ultra-Low-Level HPGe Gamma Spectra  

SciTech Connect

The GRABGAM code has been used successfully for ultra-low level HPGe gamma spectrometry analysis since its development in 1985 at Savannah River Technology Center (SRTC). Although numerous gamma analysis codes existed at that time, reviews of institutional and commercial codes indicated that none addressed all features that were desired by SRTC. Furthermore, it was recognized that development of an in-house code would better facilitate future evolution of the code to address SRTC needs based on experience with low-level spectra. GRABGAM derives its name from Gamma Ray Analysis BASIC Generated At MCA/PC.

Winn, W.G.

1999-07-28

3

Airborne Gamma-Spectrometry in Switzerland  

SciTech Connect

Airborne gamma-spectrometry is able to obtain fast radiological information over large areas. The airborne gamma-spectrometry unit deployed in Switzerland by the Swiss National Emergency Operations Centre (NEOC) consists of a Swiss army Super Puma helicopter equipped with four NaI-Detectors with a total volume of 17 liters, associated electronics and a real-time data evaluation and mapping unit developed by the Swiss Federal Institute of Technology (ETH) and the Paul Scherrer Institut (PSI). The operational readiness of the airborne gamma-spectrometry system is validated in annual exercises of one week duration. Data from 2005 and 2006 exercises are represented in maps of {sup 137}Cs activity concentration for two towns located in southern and western Switzerland. An indicator of man-made radioactivity (MMGC ratio) is demonstrated for an area with four different types of nuclear installations. The intercomparison between airborne gamma-spectrometry and ground measurements showed good agreement between both methods.

Butterweck, Gernot [Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Bucher, Benno [Swiss Federal Nuclear Safety Inspectorate, 5232 Villigen HSK (Switzerland); Rybach, Ladislaus [Swiss Federal Institute of Technology Zurich, Institute of Geophysics, 8093 Zurich (Switzerland)

2008-08-07

4

Covariance analysis of gamma ray spectra  

SciTech Connect

The covariance method exploits fluctuations in signals to recover information encoded in correlations which are usually lost when signal averaging occurs. In nuclear spectroscopy it can be regarded as a generalization of the coincidence technique. The method can be used to extract signal from uncorrelated noise, to separate overlapping spectral peaks, to identify escape peaks, to reconstruct spectra from Compton continua, and to generate secondary spectral fingerprints. We discuss a few statistical considerations of the covariance method and present experimental examples of its use in gamma spectroscopy.

Trainham, R.; Tinsley, J. [Special Technologies Laboratory of National Security Technologies, LLC, 5520 Ekwill Street, Santa Barbara, California 93111 (United States)

2013-01-15

5

Covariance Analysis of Gamma Ray Spectra  

SciTech Connect

The covariance method exploits fluctuations in signals to recover information encoded in correlations which are usually lost when signal averaging occurs. In nuclear spectroscopy it can be regarded as a generalization of the coincidence technique. The method can be used to extract signal from uncorrelated noise, to separate overlapping spectral peaks, to identify escape peaks, to reconstruct spectra from Compton continua, and to generate secondary spectral fingerprints. We discuss a few statistical considerations of the covariance method and present experimental examples of its use in gamma spectroscopy.

Trainham, R.; Tinsley, J.

2013-01-01

6

Comparison of gamma-ray coincidence and low-background gamma-ray singles spectrometry.  

PubMed

Aerosol samples have been studied under different background conditions using gamma-ray coincidence and low-background gamma-ray singles spectrometric techniques with High-Purity Germanium detectors. Conventional low-background gamma-ray singles counting is a competitive technique when compared to the gamma-gamma coincidence approach in elevated background conditions. However, measurement of gamma-gamma coincidences can clearly make the identification of different nuclides more reliable and efficient than using singles spectrometry alone. The optimum solution would be a low-background counting station capable of both singles and gamma-gamma coincidence spectrometry. PMID:22037206

Konki, J; Greenlees, P T; Jakobsson, U; Jones, P; Julin, R; Juutinen, S; Ketelhut, S; Hauschild, K; Kontro, R; Leppänen, A-P; Lopez-Martens, A; Mattila, A; Nieminen, P; Nyman, M; Peräjärvi, K; Peura, P; Rahkila, P; Ruotsalainen, P; Sarén, J; Scholey, C; Sorri, J; Toivonen, H; Turunen, J; Uusitalo, J

2012-02-01

7

Analysis of mass spectrometry data using sub-spectra  

Microsoft Academic Search

Background: Spectra resulting from Surface-Enhanced Laser Desorption\\/Ionisation (SELDI) mass spectrometry measurements are constructed by combining sub-spectra, each of which are the result of a single firing of the laser responsible for the process of desorption\\/ionisation. These firings are performed at different locations of the spot on which the sample is analysed. The final spectrum is then constructed by summing over

Wouter Meuleman; Judith Y. M. N. Engwegen; Marie-christine W. Gast; Lodewyk F. A. Wessels; Marcel J. T. Reinders

2009-01-01

8

Decomposition of ESR Spectra Using MALDI-TOF Mass Spectrometry  

E-print Network

-broadened component using a combination of optical and matrix-assisted laser desorp- tion/ionization-time-of-flight component and a doubly labeled, dipolar-broadened spectrum based on matrix-assisted laser de- sorption/ionization-time-of-flightArticles Decomposition of ESR Spectra Using MALDI-TOF Mass Spectrometry Werner L. Vos, Louic S

Hemminga, Marcus A.

9

A code to simulate nuclear reactor inventories and associated gamma-ray spectra.  

PubMed

A computer code has been developed to simulate the gamma-ray spectra that would be measured by airborne gamma spectrometry (AGS) systems from sources containing short-lived fission products. The code uses simple numerical methods to simulate the production and decay of fission products and generates spectra for sodium iodide (NaI) detectors using Monte Carlo codes. A new Monte Carlo code using a virtual array of detectors to reduce simulation times for airborne geometries is described. Spectra generated for a short irradiation and laboratory geometry have been compared with an experimental data set. The agreement is good. Spectra have also been generated for airborne geometries and longer irradiation periods. The application of this code to generate AGS spectra for accident scenarios and their uses in the development and evaluation of spectral analysis methods for such situations are discussed. PMID:11379065

Cresswell, A J; Allyson, J D; Sanderson, D C

2001-01-01

10

Gamma-ray spectra from neutron capture on Sr  

Microsoft Academic Search

The gamma-ray spectrum following neutron capture on Sr was measured at 3 neutron energies: E\\/sub n\\/ = thermal, 2 keV, and 24 keV. Gamma rays were detected in a three-crystal Ge(Li)-NaI-NaI pair spectrometer. Gamma-ray intensities deduced from these spectra by spectral unfolding are presented.

R. E. Sullivan; J. A. Becker; M. L. Stelts

1981-01-01

11

Resonant Compton scattering and gamma-ray burst continuum spectra  

NASA Technical Reports Server (NTRS)

The Thomson limit of resonant inverse Compton scattering in the strong magnetic fields of neutron stars is considered as a mechanism for producing gamma-ray burst continuum spectra. Photon production spectra and electron cooling rates are presented using the full magnetic Thomson cross-section. Model emission spectra are obtained as self-consistent solutions of a set of photon and electron kinetic equations, displaying spectral breaks and other structure at gamma-ray energies.

Baring, M. G.

1995-01-01

12

Variations of gamma radiation spectra during precipitations  

NASA Astrophysics Data System (ADS)

In the present paper results of prolonging studies of variations of a natural gamma (X-ray) radiation during precipitations registered at cosmic ray station in Apatity are presented. To the present time in the complex installation realizing monitoring of the near ground radiation, the detector is added on the basis of a scintillation crystal by size Ø150×100 mm. The special procedure of working out of the differential energy spectra obtained on the basis of this detector is designed. Due to this it is found, that increases are produced by an additional flux of radiation with the non-regular descending energy spectrum superimposed on a background radiation, having a power law energy spectrum. The clear upper energy limit of the additional radiation, accompanying with precipitations, is observed. It is 1.8-2.0 MeV. Any spectral lines, which could be produced by radionuclides, are not revealed in all researched gamut. It is concluded that these fluxes are produced by energetic charged particles during their passage through the atmosphere, i.e. Bremsstrahlung generation process. Based on the energy balance, the minimum field strength, which can cause a secondary increase, was performed.

Balabin, Yu V.; Germanenko, A. V.; Gvozdevsky, B. B.; Vashenyuk, E. V.

2013-02-01

13

Pulsar gamma-rays: Spectra luminosities and efficiencies  

NASA Technical Reports Server (NTRS)

The general characteristics of pulsar gamma ray spectra are presented for a model where the gamma rays are produced by curvature radiation from energetic particles above the polar cap and attenuated by pair production. The shape of the spectrum is found to depend on pulsar period, magnetic field strength, and primary particle energy. By a comparison of numerically calculated spectra with the observed spectra of the Crab and Vela pulsars, it is determined that primary particles must be accelerated to energies of about 3 x 10 to the 7th power mc sq. A genaral formula for pulsar gamma ray luminosity is determined and is found to depend on period and field strength.

Harding, A. K.

1980-01-01

14

GAMMA SPECTRA OF GROSS FISSION PRODUCTS FROM THERMAL REACTORS  

Microsoft Academic Search

Calculations of gamma spectra from products of thermal fission of U\\/sup ; 235\\/ are presented. The fission yield values and decay data used are taken from ; literature published up to April 1958. The calculations cover seven different ; irradiation times from one day to two years and continuous cooling times from one ; day to 1000 years. The gamma

J. Prawitz; K. Low; R. Bjornerstedt

1959-01-01

15

A COMPARISON OF GADRAS SIMULATED AND MEASURED GAMMA RAY SPECTRA  

SciTech Connect

Gamma-ray radiation detection systems are continuously being developed and improved for detecting the presence of radioactive material and for identifying isotopes present. Gamma-ray spectra, from many different isotopes and in different types and thicknesses of attenuation material and matrixes, are needed to evaluate the performance of these devices. Recently, a test and evaluation exercise was performed by the Savannah River National Laboratory that required a large number of gamma-ray spectra. Simulated spectra were used for a major portion of the testing in order to provide a pool of data large enough for the results to be statistically significant. The test data set was comprised of two types of data, measured and simulated. The measured data were acquired with a hand-held Radioisotope Identification Device (RIID) and simulated spectra were created using Gamma Detector Response and Analysis Software (GADRAS, Mitchell and Mattingly, Sandia National Laboratory). GADRAS uses a one-dimensional discrete ordinate calculation to simulate gamma-ray spectra. The measured and simulated spectra have been analyzed and compared. This paper will discuss the results of the comparison and offer explanations for spectral differences.

Jeffcoat, R.; Salaymeh, S.

2010-06-28

16

Monte Carlo simulations of plutonium gamma-ray spectra  

SciTech Connect

Monte Carlo calculations were investigated as a means of simulating the gamma-ray spectra of Pu. These simulated spectra will be used to develop and evaluate gamma-ray analysis techniques for various nondestructive measurements. Simulated spectra of calculational standards can be used for code intercomparisons, to understand systematic biases and to estimate minimum detection levels of existing and proposed nondestructive analysis instruments. The capability to simulate gamma-ray spectra from HPGe detectors could significantly reduce the costs of preparing large numbers of real reference materials. MCNP was used for the Monte Carlo transport of the photons. Results from the MCNP calculations were folded in with a detector response function for a realistic spectrum. Plutonium spectrum peaks were produced with Lorentzian shapes, for the x-rays, and Gaussian distributions. The MGA code determined the Pu isotopes and specific power of this calculated spectrum and compared it to a similar analysis on a measured spectrum.

Koenig, Z.M.; Carlson, J.B.; Wang, Tzu-Fang; Ruhter, W.D.

1993-07-16

17

Augmentation of ENDF/B fission product gamma-ray spectra by calculated spectra  

SciTech Connect

Gamma-ray spectral data of the ENDF/B-V fission product decay data file have been augmented by calculated spectra. The calculations were performed with a model using beta strength functions and cascade gamma-ray transitions. The calculated spectra were applied to individual fission product nuclides. Comparisons with several hundred measured aggregate gamma spectra after fission were performed to confirm the applicability of the calculated spectra. The augmentation was extended to a preliminary ENDF/B-VI file, and to beta spectra. Appendix C provides information on the total decay energies for individual products and some comparisons of measured and aggregate values based on the preliminary ENDF/B-VI files. 15 refs., 411 figs.

Katakura, J. (Japan Atomic Energy Research Inst., Tokai-mura, Naka-gun, Ibaraki-ken (Japan)) [Japan Atomic Energy Research Inst., Tokai-mura, Naka-gun, Ibaraki-ken (Japan); England, T.R. (Los Alamos National Lab., NM (United States)) [Los Alamos National Lab., NM (United States)

1991-11-01

18

Further development of IDGS: Isotope dilution gamma-ray spectrometry  

NASA Astrophysics Data System (ADS)

The isotope dilution gamma-ray spectrometry (IDGS) technique for determining the plutonium concentration and isotopic composition of highly radioactive spent-fuel dissolver solutions has been further developed. Both the sample preparation and the analysis have been improved. The plutonium isotopic analysis is based on high-resolution, low-energy gamma-ray spectrometry. The plutonium concentration in the dissolver solutions then is calculated from the measured isotopic differences among the spike, the dissolver solution, and the spiked dissolver solution. Plutonium concentrations and isotopic compositions of dissolver solutions analyzed from this study agree well with those obtained by traditional isotope dilution mass spectrometry (IDMS) and are consistent with the first IDGS experimental result. With the current detector efficiency, sample size, and a 100-min count time, the estimated precision is approximately 0.5 percent for Pu-239 and Pu-240 isotopic analyses and approximately 1 percent for the plutonium concentration analysis.

Li, T. K.; Parker, J. L.; Kuno, Y.; Sato, S.; Kamata, M.; Akiyama, T.

19

Imaging Neutron Activation Analysis and Multiplexed Gamma Ray Spectrometry.  

NASA Astrophysics Data System (ADS)

This work demonstrates for the first time the feasibility of Imaging Neutron Activation Analysis (Imaging NAA) and of multiplexed gamma-ray spectrometry. The two techniques are based on position sensitive beta -gamma coincidence measurement using a gamma-ray detector, a charged particle imaging detector and a coincidence system. Imaging NAA is a technique for determining the 2-dimensional elemental distributions in heterogeneous samples. With multiplexed gamma-ray spectrometry it is possible to count an array of samples simultaneously which results in a substantial reduction in total counting time and also low background because of the coincidence measurement. Two distinctly different charged particle imaging detectors were investigated for electron localization. They were: (1) an electron optics based system for low energy secondary electron imaging and (2) a Position Sensitive Photomultiplier Tube (PSPMT) coupled to a thin plastic scintillator for beta imaging. The secondary electron imaging system offers a spatial resolution of 30 ?m but its active imaging area is only 1 mm in diameter, and the beta detection efficiency is less than 10%. The PSPMT gives a spatial resolution of 2.5 mm FWHM with a 60 x 55 mm^2 active area and a beta detection efficiency of up to 36%. The secondary electron imaging system is suitable for element mapping of small continuous heterogeneous samples, while the PSPMT is suitable for multiplexed gamma-ray spectrometry of discrete samples. Results show that using the PSPMT it is possible to multiplex 100 samples, which results in up to a factor of 36 gain in total counting time compared to counting the samples individually. Experimental results that demonstrate the two techniques are presented for various radionuclides that undergo beta, alpha or EC decay followed by coincident gamma -ray emission.

Dewaraja, Yuni Kamalika

20

Seabed gamma-ray spectrometry: applications at IAEA-MEL.  

PubMed

The technique of underwater gamma-ray spectrometry has been developed to complement or replace the traditional sampling-sample analysis approach for applications with space-time constraints, e.g. large areas of investigation, emergency response or long-term monitoring. IAEA-MEL has used both high-efficiency NaI(Tl) and high-resolution HPGe spectrometry to investigate contamination with anthropogenic radionuclides in a variety of marine environments. Surveys at the South Pacific nuclear test sites of Mururoa and Fangataufa have been used to guide sampling in areas of high contamination around ground zero points. In the Irish Sea offshore from the Sellafield nuclear reprocessing plant, a gamma-ray survey of seabed sediment was carried out to obtain estimates of the distribution and subsequently, for the inventory of 137Cs in the investigated area. PMID:11379061

Osvath, I; Povinec, P P

2001-01-01

21

Automated gamma spectrometry and data analysis on radiometric neutron dosimeters  

Microsoft Academic Search

An automated gamma-ray spectrometry system was designed and implemented by the Westinghouse Hanford Company at the Hanford Engineering Development Laboratory (HEDL) to analyze radiometric neutron dosimeters. Unattended, automatic, 24 hour\\/day, 7 day\\/week operation with online data analysis and mainframe-computer compatible magnetic tape output are system features. The system was used to analyze most of the 4000-plus radiometric monitors (RM's) from

1983-01-01

22

Magnetic photon splitting and gamma ray burst spectra  

NASA Technical Reports Server (NTRS)

The splitting of photons into two photons becomes both possible and significant in magnetic fields in excess of 10(exp 12) Gauss. Below the threshold energy, 2m sub e c(exp 2) for single photon pair production, splitting can be an astronomically observable phenomenon evident in gamma ray burst spectra. In such circumstances, it was found that magnetic photon splitting reprocesses the gamma ray burst continuum by degrading the photon energy, with a net effect that is quite similar to pair cascade reprocessing of the spectrum. Results are presented for the spectral modifications due to splitting, taking into account the different probabilities for splitting for different polarization modes. Unpolarized and polarized pair cascade photon spectra form the input spectra for the model, which calculates the resulting splitting reprocessed spectra numerically by solving the photon kinetic equations for each polarization mode. This inclusion of photon polarizations is found to not alter previous predictions that splitting produce a significant flattening of the hard X ray continuum and a bump at MeV energies below a pair production turnover. The spectrum near the bump is always strongly polarized.

Baring, Matthew G.

1992-01-01

23

Computerized gamma spectrometry at the Helsinki University of Technology  

NASA Astrophysics Data System (ADS)

In this paper we describe our approach to designing a system for rapid and accurate processing of gamma spectra. Our measurements are done in a separate measuring station which consists of conventional equipment centered around a multichannel analyzer. The measured spectra are then transferred to a Nova 2 minicomputer based analysis station via a 70 m long cable at a 9600 baud rate with a special control program. Analyses can be performed with our new SAMPO80 code on the Nova or the data can be further transferred into the computer network of the University with another control program. Various aspects of the system design and development are discussed.

Aarnio, P. A.; Koskelo, M. J.

24

Airborne gamma spectrometry--towards integration of European operational capability.  

PubMed

Airborne gamma spectrometry is an excellent tool for finding out in a timely manner the extent and magnitude of the dispersion of radioactive materials resulting from a nuclear disaster. To utilise existing European airborne monitoring capabilities for multilateral assistance in an accident is a complex administrative and technical matter. Several international exercises have been organised demonstrating the capability to cooperate. However, efficient mutual assistance between European countries requires conceptual work, standards and harmonisation of software. A unified radiological vocabulary and data exchange format in XML need to be developed. A comprehensive database is essential for data assimilation. An operations centre is needed for management and planning of surveys. PMID:15238672

Toivonen, Harri

2004-01-01

25

Basic characterization of highly enriched uranium by gamma spectrometry  

E-print Network

Gamma-spectrometric methods suitable for the characterization of highly enriched uranium samples encountered in illicit trafficking of nuclear materials are presented. In particular, procedures for determining the 234U, 235U, 238U, 232U and 236U contents and the age of highly enriched uranium are described. Consequently, the total uranium content and isotopic composition can be calculated. For determining the 238U and 232U contents a low background chamber was used. In addition, age dating of uranium was also performed using low-background spectrometry.

Cong Tam Nguyen; Jozsef Zsigrai

2005-08-25

26

Gamma spectrometry of 234Th (238U) in environmental samples.  

PubMed

Environmental samples from a wide-range of aquatic and soil deposits, mainly of Scandinavian origin, were analysed for 234Th (238U) using low-level gamma-spectrometry. The diversity of the samples, in terms of composition and ages, allowed a detailed evaluation of the analytical problems associated with gamma-ray spectrometry with focus on the reliability of the 234Th peaks for absolute determination of the 234Th activities. The X-ray contributions in the 93 keV peak were compared with the corresponding self-absorption corrected activities of the 63 keV peak. These X-ray contributions were, also, correlated with the 238U, 232Th, 235U, 40K and 137Cs activities of the samples. Despite the difficulties imposed by the self-absorption corrections, the 63 keV peak is still the best option. Large variability in the 93 keV peak interferences, due to X-rays from Th, exists in sediment and soil samples. Only in the case of young ombrotrophic peat samples was it possible to conclude that the 93 keV peak is free from X-ray contributions and can be as good as the 63 keV Monte-Carlo self-absorption corrected peak. X-ray contributions in the samples correlated with the 238U and 232Th activities, only, in closed environmental systems where a secular equilibrium with the daughters of the U/Th series can occur. PMID:12173662

El-Daoushy, Farid; Hernández, Francisco

2002-07-01

27

Full-spectrum analysis of natural gamma-ray spectra.  

PubMed

In this paper, a new system to measure natural gamma-radiation in situ will be presented. This system combines a high-efficiency BGO scintillation detector with full-spectrum data analysis (FSA). This technique uses the (nearly) full spectral shape and the so-called 'standard spectra' to calculate the activity concentrations of 40K, 232Th and 238U present in a geological matrix (sediment, rock, etc.). We describe the FSA and the determination of the standard spectra. Standard spectra are constructed for various geometries and a comparison in intensity and shape will be made. The performance of such a system has been compared to a more traditional system, consisting of a NaI detector in combination with the 'windows' analysis. For count rates typically encountered in field experiments, the same accuracy is obtained 10-20 times faster using the new system. This allows for shorter integration times and hence shorter measurements or a better spatial resolution. The applicability of such a system will be illustrated via an example of an airborne experiment in which the new system produced results comparable to those of much larger traditional systems. This paper will conclude with a discussion of the current status of the system and an outlook for future research. PMID:11379063

Hendriks, P H; Limburg, J; de Meijer, R J

2001-01-01

28

Investigation of elemental analysis using neutron-capture gamma ray spectra  

E-print Network

This thesis evaluated the potential of neutron-capture gamma rays in elemental analysis. A large portion of the work was devoted to the development of a method for the analysis of weak peaks in gamma ray spectra. This was ...

Hamawi, John Nicholas

1969-01-01

29

The low energy spectra of gamma-ray bursts  

NASA Technical Reports Server (NTRS)

The implications of observed gamma-ray burst spectra for the physical conditions and geometries of the sources are examined. It is noted that an explanation of the continua in terms of optically thin thermal bremsstrahlung requires a relatively large area but a fairly shallow depth. On the other hand, a spectrum similar to that observed could be produced by rapid flickering of sources with less extreme geometries if each flicker emits a Comptonized thermal spectrum. Either field inhomogeneities or plasma motions are required to interpret the low energy features as cyclotron extinction. An alternative explanation is photoelectric absorption by heavy atoms; this requires a field strength high enough to make one-photon electron positron annihilation possible. Observational tests of these possibilities are proposed

Bussard, R. W.; Lamb, F. K.

1982-01-01

30

Understanding the Continuum Spectra of Short Soft Gamma Repeater Bursts  

NASA Technical Reports Server (NTRS)

The spectra of short soft gamma repeater (SGR) bursts at photon energies above -15 keV are often well described by an optically thin thermal bremsstrahlung model (i.e., F(E) - E^-1 * exp(-E/kT) ) with kT=20-40 keV. However, the spectral shape burst continuum at lower photon energies (down to -2 keV) is not well established. It is important to better understand the SGR burst spectral properties at lower energies since inadequate description of the burst spectral continuum could lead to incorrect conclusions, such as existence of spectral lines. Here, we present detailed spectral investigations (in 2-200 keV) of 163 bursts from SGR 1806-20, all detected with Rossi X-ray Timing Explorer during the 2004 active episode that included the giant flare on 27 December 2004. We find that the great majority of burst spectra are well represented by the combination of a blackbody plus a OTTB models.

Gogus, Ersin; Woods, Peter M.; Kouveliotou, Chryssa; Finger, Mark H.; Lenter, Geoffrey; Patel, Sandeep K.; Swank, Jean

2006-01-01

31

Contribution of a germanium detector in mobile gamma-ray spectrometry. Spectral analysis and performance  

NASA Astrophysics Data System (ADS)

The sensitivity of the germanium semi-conductor detector is 30 times lower than that of the sodium iodide (NaI) detectors frequently used in airborne spectrometry. Its energy resolution however, is 20 times better, giving more accurate identification of radionuclides, especially when complex spectra are involved. The use of the germanium detector in mobile gamma-ray spectrometry provides a large amount of qualitative and quantitative information. In post-accident situations a germanium detector will be sufficient, and should therefore be used in preference to a NaI detector. An algorithm for detecting the total absorption peaks by studying the variations in the spectral profile of germanium gamma-ray spectra has been developed at the CEA. The use of digital filters that take into account the characteristics of the absorption peaks reduces the statistical fluctuations, making possible detection based on the analysis of the first and second derivatives. The absorption peak is then estimated by subtracting the background noise modelled in the detection window. This method of analysis offers the advantage of not requiring prior knowledge of the number or nature of the radionuclides to be detected. A study has been carried out to assess the specific performances of this detection software in different situations: average background noise in France and detection of artificial sources with varying activity levels. This analysis showed that the performance of our detection algorithm is very close to the theoretical detection limits, for both natural and artificial radionuclides. This algorithm is therefore well suited to the germanium type of spectral profile and to low count rates.

Gutierrez, S.; Guillot, L.; Bourgeois, C.

2002-04-01

32

Continuous gamma-ray spectrometry in the Fast Flux Test Facility (FFTF)  

NASA Astrophysics Data System (ADS)

Gamma ray continua were measured at startup in the Fast Flux Test Facility (FFTF). A special FFTF insert, called the In-Reactor Thimble (IRT), provided an adequate environment for in situ operation of the gamma spectrometer. The IRT replaced a fuel assembly near core center (No. 2101) and measurements were conducted at three axial locations, namely midplane, the lower axial shield, and the upper axial reflector. Observations were carried out with Compton Recoil Gamma Ray Spectrometry at the state of the art. Advantage was thereby taken of the most recent advances, including extension of gamma ray spectrometry up to roughly 7 MeV with the new in situ Janus detector probe.

Gold, R.; Kaiser, B. J.; Moore, F. S., Jr.; Bunch, W. L.; McElroy, W. N.; Sheen, E. M.

1980-10-01

33

Cadium-Zinc-Telluride (CZT) Gamma Ray Spectrometry  

SciTech Connect

This report describes CZT crystals and their use in large arrays for generation of gamma ray spectra. Laboratory spectra will be shown together with spectra accumulated by various battery powered portable instruments (see Appendix A). One of these portable instruments was specifically constructed to minimize power consumption and yet provide reasonable isotope identification capability. Detailed data will be presented covering gamma energy resolution, gamma peak shapes, system background, and detector efficiency. Nearly all data were taken with very small crystals of CZT; cubes 5 mm on a side. A few spectra will be presented from cylindrical crystals of about the same size (see Appendix A). The small crystal size leads to low counting rates and extended counting times for reliable isotope identification. We have addressed this problem by using arrays of CZT crystals, initially two crystals and, at present, arrays of eight crystals. Data will be shown relating spectral parameters for these two arrays. System MDA is one way of combining resolution, efficiency, and background that will enable direct comparison of various detector types for individual isotope identification. We have calculated the MDA for an early dual crystal array and the current eight crystal array. Data derived from each array will be presented. In addition, it is possible to extrapolate the MDA methodology to much larger arrays. A 32-crystal array is under construction and extrapolations to 256 and 1024 crystals are considered possible. Estimated MDA values for these larger arrays are also presented. Several 8-crystal arrays have been constructed and versions have been incorporated into portable instruments. Descriptions of these small instruments are given covering physical size, weight, and general configuration. These instruments have been tested for shock and temperature effects and data will be presented on the results of these tests. The MDA concept will also allow extrapolation to large source to detector distances. The usual laboratory measurements are done with small sources at 20 to 50 cm ranges. Practical ranges for aerial work will be 50 to 100 meters or greater. These distances will require correction for air attenuation for most of the low energy isotopes. The approximations used in the present note for aerial measurements involve small diameter sources (diameter approximately equal to the altitude), a 1 kt pass, and a planar array with no aircraft attenuation material in the field of view. The array will have a collimator to limit the side-looking sensitivity to enable a more accurate extrapolation from the laboratory data. Large arrays will have significant physical size and weight compared to the small hand-held instruments thus far constructed. We estimate these parameters and extrapolate the power consumption to provide a realistic estimate of a suitable airborne system. In all cases these larger systems are lighter and physically more compact than the usual NaI or high purity Germanium (HPGe) systems used in aerial work. Thus deployment should be simple. The power consumption is much less as well.

William Quam

2001-09-01

34

Measured neutron and gamma spectra from californium-252 in a tissue-equivalent medium.  

PubMed

A method of experimentally obtaining both neutron and gamma-ray spectra in a scattering medium is described. The method utilizes a liquid-organic scintillator (NE-213) coupled with a pulse-shape discrimination circuit. This allows the separation of the neutron-induced pulse-height data from the gamma-ray pulse-height data. Using mathematical unfolding techniques, the two sets of pulse-height data were transformed to obtain the neutron and gamma-ray energy spectra. A small spherical detector was designed and constructed to reduce the errors incurred by attempting spectral measurements in a scattering medium. Demonstration of the utility of the system to obtain the neutron and gamma-ray spectra in a scattering medium was performed by characterizing the neutron and gamma-ray spectra at various sites about a 3.7-microgram (1.5 cm active length) californium-252 source in a tissue-equivalent medium. PMID:492077

Elson, H R; Stupar, T A; Shapiro, A; Kereiakes, J G

1979-01-01

35

Gamma spectrometry and plastic-scintillator inherent background  

Microsoft Academic Search

The authors measured the energy resolution for a linear dependence of light yield on gamma radiation energy of gamma spectrometers based on plastic scintillation detectors for several plastic scintillators. If there were several gamma lines from the source the line with the highest energy was used to eliminate distortion due to overlap from the Compton background from gamma radiation of

V. V. Pomerantsev; I. B. Gagauz; L. I. Mitsai; V. S. Pilipenko; V. M. Solomonov; V. V. Chernikov; Y. A. Tsirlin

1988-01-01

36

In-situ gamma spectrometry measurements of time-dependent Xenon-135 inventory in the TRIGA Mark II reactor Vienna  

E-print Network

In this work, it has been shown that the time dependent Xe-135 inventory in the TRIGA Mark II reactor in Vienna, Austria can be measured via gamma spectrometry even in the presence of strong background radiation. It is focussing on the measurement of (but not limited to) the nuclide Xe-135. The time dependent Xe-135 inventory of the TRIGA Mark II reactor Vienna has been measured using a temporary beam line between one fuel element of the core placed onto the thermal column after shutdown and a detector system located just above the water surface of the reactor tank. For the duration of one week, multiple gamma ray spectra were recorded automatically, starting each afternoon after reactor shutdown until the next morning. One measurement series has been recorded over the weekend. The Xe-135 peaks were extracted from a total of 1227 recorded spectra using an automated peak search algorithm and analyzed for their time-dependent properties. Although the background gamma radiation present in the core after shutdown was large especially in the lower energy range, the Xe-135 peak located at 249.8 keV could be extracted from the most spectra where present and could be compared to theoretical calculations.

Julia Riede; Helmuth Boeck

2013-07-29

37

Quantification of uranium-238 in environmental samples using gamma-ray spectrometry  

NASA Astrophysics Data System (ADS)

A large number of environmental samples are routinely measured world-wide using gamma-ray spectrometry some of its assets being easy sample preparation and comprehensive data for many radionu-clides in one analysis. Although other techniques can be considered more suitable for analysing 238U in environmental samples, it is also routinely done by gamma-ray spectrometry. One mainly uses ?-ray emissions following the decay of the first daughter, 234Th, for determining the 238U activity. However, the low-energy gamma-rays at 63 keV and 92.5 keV are very difficult to quantify in a robust way due to high attenuation and interferences. This paper quantifies parameters affecting the possibility of making robust quantification of 238U via 234Th using gamma-ray spectrometry. It addresses the use of correct decay data, suitable detectors, optimised sample size, enhanced spectral amplification, correction for peak interferences and control of background.

Hult, M.; Andreotti, E.; González de Orduña, R.; Pommé, S.; Yeltepe, E.

2012-04-01

38

Time-Integrated Gamma-Ray Burst Synchrotron Spectra from Blast Wave/Cloud Interactions  

E-print Network

We show that the spectral shape of the low energy tails found for the time-integrated spectra of gamma-ray bursts, even in the absence of strong synchrotron cooling, can be significantly softer than the $\

James Chiang

1998-10-15

39

Study of Total Gamma Spectra Correlation for Extending Identification Range over Photopeak Analysis.  

National Technical Information Service (NTIS)

This report shows that gamma spectra identification by total flux correlation can be used to extend identification range over photo peak methods. Identification was based on two decision rules both employing cross-correlation coefficients. The largest coe...

A. W. Dooley

1984-01-01

40

Spectra, fluxes, and observability of gamma rays from dark matter annihilation in the Galaxy  

NASA Technical Reports Server (NTRS)

Details of the physics of gamma-ray production by the annihilation of dark matter particles in the Galaxy are presented. Improved gamma-ray spectra and fluxes are calculated and compared with present observational data on cosmic gamma-ray fluxes at high Galactic latitudes. A comparison with the gamma-ray flux from cosmic-ray interactions is made. It is found that gamma-rays from dark matter annihilation are most potentially observable from patches of the sky at high Galactic latitudes in directions having an unusually low total column density of gas and from a dark matter core at the Galactic center.

Stecker, F. W.; Tylka, A. J.

1989-01-01

41

International Journal of Mass Spectrometry 258 (2006) 5873 SpectraMiner, an interactive data mining and visualization software for  

E-print Network

International Journal of Mass Spectrometry 258 (2006) 58­73 SpectraMiner, an interactive data mining and visualization software package we call SpectraMiner that makes it possible to handle hundreds that puts the classification aspect of SpectraMiner to the test. Twelve types of laboratory generated

Mueller, Klaus

42

Statistical methods for the chemical compound identification from neutron-induced gamma-ray spectra  

Microsoft Academic Search

The paper presents a list correlation method to identify specific high explosive (HE) compounds from the spectra derived from reconstructed images of a gamma- ray camera. The correlation method uses all the information of the characteristic gamma rays for the associated elements of a compound. We show that the method is able to identify HE material at the compound level

Randy C. Stevenson; Joonki Noh; Mark D. Hammig

2009-01-01

43

BATSE Observations of Gamma-Ray Burst Spectra. Part 3; Low-Energy Behavior of Time-Averaged Spectra  

NASA Technical Reports Server (NTRS)

We analyze time-averaged spectra from 86 bright gamma-ray bursts from the first 5 years of the Burst And Transient Source Experiment (BATSE) on board the Compton Gamma Ray Observatory to determine whether the lowest energy data are consistent with a standard spectra form fit to the data at all energies. The BATSE Spectroscopy Detectors have the capability to observe photons as low as 5 keV. Using the gamma-ray burst locations obtained with the BATSE Large Area Detectors, the Spectroscopy Detectors' low-energy response can be modeled accurately. This, together with a postlaunch calibration of the lowest energy Spectroscopy Detector discriminator channel, which can lie in the range 5-20 keV, allows spectral deconvolution over a broad energy range, approx. 5 keV to 2 MeV. The additional coverage allows us to search for evidence of excess emission, or for a deficit, below 20 keV. While no burst has a significant (greater than or equal to 3 sigma) deficit relative to a standard spectra model, we find that 12 bursts have excess low-energy emission, ranging between 1.2 and 5.8 times the model flux, that exceeds 5 sigma in significance. This is evidence for an additional low-energy spectral component in at least some bursts, or for deviations from the power-law spectral form typically used to model gamma-ray bursts at energies below 100 keV.

Preece, R. D.; Briggs, M. S.; Pendleton, G. N.; Paciesas, W. S.; Matteson, J. L.; Band, D. L.; Skelton, R. T.; Meegan, C. A.

1996-01-01

44

Portable microcomputer unit for the analysis of plutonium gamma-ray spectra  

SciTech Connect

A portable microcomputer has been developed for the IAEA to perform in-field analysis of plutonium gamma-ray spectra. The unit includes a 16-bit LSI-11/2 microprocessor, 32K words of memory, a 20-character display for user prompting, and a 20-character thermal printer for hardcopy output. Only the positions of the 148-keV Pu-241 and 208-keV U-237 peaks are required for spectral analysis. The unit was tested against gamma-ray spectra taken of NBS plutonium standards and IAEA spectra. Results obtained are presented.

Ruhter, W.D.; Camp, D.C.

1981-10-01

45

Decay heat of ²³U fission products by beta- and gamma-ray spectrometry  

Microsoft Academic Search

The fast-rabbit facilities of the ORRR were used to irradiate 1- to 10-..mu..g samples of ²³U for 1, 10, and 100 s. Released power is observed using nuclear spectroscopy to permit separate observations of emitted ..beta.. and ..gamma.. spectra in successive time intervals. The spectra were integrated over energy to obtain total decay heat and the ..beta..- and ..gamma..-ray results

J. K. Dickens; T. A. Love; J. W. McConnell; R. W. Peelle

1976-01-01

46

In-situ gamma spectrometry measurements of time-dependent Xenon-135 inventory in the TRIGA Mark II reactor Vienna  

E-print Network

In this work, it has been shown that the time dependent Xe-135 inventory in the TRIGA Mark II reactor in Vienna, Austria can be measured via gamma spectrometry even in the presence of strong background radiation. It is focussing on the measurement of (but not limited to) the nuclide Xe-135. The time dependent Xe-135 inventory of the TRIGA Mark II reactor Vienna has been measured using a temporary beam line between one fuel element of the core placed onto the thermal column after shutdown and a detector system located just above the water surface of the reactor tank. For the duration of one week, multiple gamma ray spectra were recorded automatically, starting each afternoon after reactor shutdown until the next morning. One measurement series has been recorded over the weekend. The Xe-135 peaks were extracted from a total of 1227 recorded spectra using an automated peak search algorithm and analyzed for their time-dependent properties. Although the background gamma radiation present in the core after shutdown...

Riede, Julia

2013-01-01

47

Small scale local gamma ray features. [galactic radiation spectra  

NASA Technical Reports Server (NTRS)

In order to draw implications from nearby gamma-ray emission, the different ways that can be used to obtain an estimate of the amount of matter on each line of sight are investigated. It is shown that, within present uncertainties, the cosmic ray intensity inside molecular clouds within 1 kpc from the sun is the same as the cosmic ray intensity measured at the sun. In the last part, what can be learned from a comparison of far infrared and gamma-ray data is discussed.

Puget, J. L.; Ryter, C.; Serra, G.

1977-01-01

48

QUALITY CONTROL FOR ENVIRONMENTAL MEASUREMENTS USING GAMMA-RAY SPECTROMETRY  

EPA Science Inventory

This report describes the quality control procedures, calibration, collection, analysis, and interpretation of data in measuring the activity of gamma ray-emitting radionuclides in environmental samples. Included in the appendices are basic data for selected gamma ray-emitting ra...

49

Taking borehole conditions algorithmically into account in the. gamma. spectrometry of rock  

SciTech Connect

In the present work, an analytical model permitting an operative algorithmic interpretation of the data of borehole gamma spectrometry is briefly described. The spectrometry of the natural gamma radiation of rock permits significant increase in the efficiency of solving problems of oil-gas geophysics associated with the surveying and exploitation of oil and gas deposits, calculation of the reserves, and increasing the petroleum output of beds. The meteorological parameters of the interpretational model are presented. The universal dependence of the bed value for a centered instrument and an instrument passed to the borehole wall on the dimensionless parameter is shown.

Kozhevnikov, D.A.

1987-01-01

50

Temperature dependence of gain shift in gamma-ray spectrometry system involving a long connecting cable.  

PubMed

This work demonstrates the possibility of a gain shift or a peak-shape-deterioration with changes in the temperature of a long connecting cable between a pre-amplifier and a main amplifier in a Ge gamma-ray spectrometry system. The tests were performed for 50m-long RG174/U and RG58C/U cables with and without the termination. Such a temperature effect may cause from the temperature dependence of the resistivity of a central copper wire. In order to minimize such temperature effects in a Ge gamma-ray spectrometry, use of a terminator should be avoided. PMID:20022513

Kawada, Y; Yamada, T; Nagai, A

2010-01-01

51

Total Absorption Gamma-ray Spectrometer (TAGS) Intensity Distributions from INL's Gamma-Ray Spectrometry Center  

DOE Data Explorer

A 252Cf fission-product source and the INL on-line isotope separator were used to supply isotope-separated fission-product nuclides to a total absorption -ray spectrometer. This spectrometer consisted of a large (25.4-cm diameter x 30.5-cm long) NaI(Tl) detector with a 20.3-cm deep axial well in which is placed a 300-mm2 x 1.0-mm Si detector. The spectra from the NaI(Tl) detector are collected both in the singles mode and in coincidence with the B-events detected in the Si detector. Ideally, this detector would sum all the energy of the B- rays in each cascade following the population of daughter level by B- decay, so that the event could be directly associated with a particular daughter level. However, there are losses of energy from attenuation of the rays before they reach the detector, transmission of rays through the detector, escape of secondary photons from Compton scattering, escape of rays through the detector well, internal conversion, etc., and the measured spectra are thus more complicated than the ideal case and the analysis is more complex. Analysis methods have been developed to simulate all of these processes and thus provide a direct measure of the B- intensity distribution as a function of the excitation energy in the daughter nucleus. These data yield more accurate information on the B- distribution than conventional decay-scheme studies for complex decay schemes with large decay energies, because in the latter there are generally many unobserved and observed but unplaced rays. The TAGS data have been analyzed and published [R. E. Greenwood et al., Nucl Instr. and metho. A390(1997)] for 40 fission product-nuclides to determine the B- intensity distributions. [Copied from the TAGS page at http://www.inl.gov/gammaray/spectrometry/tags.shtml]. Those values are listed on this page for quick reference.

Greenwood, R.E.

52

A simple method for the absolute determination of uranium enrichment by high-resolution gamma spectrometry.  

PubMed

A simple method for the determination of uranium enrichment using high-resolution gamma spectrometry is presented in this paper. The method relies solely on the gamma-ray emission probabilities of 235U and 234mPa, and an iterative procedure for the least squares fit of a polynomial to a set of experimentally determined data. To ensure the reliability of the 234mPa gamma-ray emission probabilities employed, a new determination of these probabilities was carried out using a combination of gamma spectrometry and Cerenkov counting of a purified 234Th solution. Using these new data, a maximum difference of approximately 5% has been found between the experimental and declared uranium enrichment in a set of solid and liquid samples containing uranium compounds. PMID:16311038

Korob, R O; Blasiyh Nuño, G A

2006-05-01

53

Measured neutron and gamma spectra from californium-252 in a tissue-equivalent medium  

Microsoft Academic Search

A method of experimentally obtaining both neutron and gamma-ray spectra in a scattering medium is described. The method utilizes a liquid-organic scintillator (NE-213) coupled with a pulse-shape discrimination circuit. This allows the separation of the neutron-induced pulse-height data from the gamma-ray pulse-height data. Using mathematical unfolding techniques, the two sets of pulse-height data were transformed to obtain the neutron and

Howard R. Elson; Terry A. Stupar; Alvin Shapiro; James G. Kereiakes

1979-01-01

54

A computer procedure for the resolution of gamma spectra having coincident peaks  

E-print Network

A COMPUTER PROCEDURE FOR THE RESOLUTION OF GAMMA SPECTRA HAVING COi NC'DENT PEAKS A Thesis By BARRY LYNN BATEMAN Submitted to the Graduate Col lege of the Texas AKIM Uni vers ity ! n partial fulfi Iment of the requirements for the degree... of MASTER OF SC'ENCE January 1967 Major Subject: Computer Science A COMPUTER PROCEDURE FOR THE RESOLUTION OF GAMMA SPECTRA HAVING COINCIDENT PEAKS A Thesis By BARRY LYNN BATEMAN Approved as to style and content by: (Chairman of Cormittee) ( Pad...

Bateman, Barry Lynn

2012-06-07

55

Continuum spectra for gamma-ray bursts: Suppressing the soft photons  

SciTech Connect

Gamma-ray bursts are observed to have very steep spectra below photon energy /approximately/100 keV; some have photon number spectra as steep as F /proportional to/ E/sup 0/. This property has been difficult to explain in terms of most radiation processes. The BATSE experiment on the Gamma Ray Observatory should be able to test how common this spectral property is and whether there are bursts with even steeper low-energy spectra. To explain this spectral steepness, we study a model in which the /gamma/ radiation is produced by inverse-Compton and cyclotron scattering of blackbody radiation from the surface of a neutron star by relativistic electrons. If the neutron star has negligible magnetic field, Compton scattering dominates in producing the observed gamma-ray burst spectra. If the field exceeds 10/sup 10/ G, cyclotron scattering is more important. In the low-magnetic-field case, steep spectra may be produced via the suppression of the low energy part of the ''cooling spectrum'' (the spectrum integrated over the radiation lifetime of an electron), as a result of the smaller and more collimated photon flux an electron sees as it moves away from the neutron star. In the high-magnetic-field case, low-energy suppression occurs because electrons with higher energies scatter the blackbody photons more efficiently due to the cyclotron resonance, preferentially producing high energy photons. 27 refs., 5 figs.

Ho, Cheng; Epstein, R.I.

1989-01-01

56

Pulser injection with subsequent removal for gamma-ray spectrometry  

DOEpatents

An improved system for gamma-ray spectroscopy characterized by an interface module that controls the injection of electronic pulses as well as separation logic that enables storage of pulser events in a region of the spectrum of a multichannel analyzer distinct from the region reserved for storage of gamma-ray events. The module accomplishes this by tagging pulser events (high or low) injected into the amplification circuitry, adding an offset to the events so identified at the time the events are at the output of the analog to digital converter, and storing such events in the upper portion of the spectrum stored in the multichannel analyzer. The module can be adapted for use with existing gamma-ray spectroscopy equipment to provide for automatic analyses of radioisotopes.

Hartwell, Jack K. (Idaho Falls, ID); Goodwin, Scott G. (Idaho Falls, ID); Johnson, Larry O. (Blackfoot, ID); Killian, E. Wayne (Idahoe Falls, ID)

1990-01-01

57

Study of total gamma spectra correlation for extending identification range over photopeak analysis. Master's thesis  

Microsoft Academic Search

This report shows that gamma spectra identification by total flux correlation can be used to extend identification range over photo peak methods. Identification was based on two decision rules both employing cross-correlation coefficients. The largest coefficient (first decision rule) matched the unknown spectra with the correct source thirty-seven out of thirty-eight trials. The proposed likelihood function (second decision rule) had

Dooley

1984-01-01

58

Study of total gamma spectra correlation for extending identification range over photopeak analysis  

Microsoft Academic Search

This report shows that gamma spectra identification by total flux correlation can be used to extend identification range over photo peak methods. Identification was based on two decision rules both employing cross-correlation coefficients. The largest coefficient (first decision rule) matched the unknown spectra with the correct source thirty-seven out of thirty-eight trials. The proposed likelihood function (second decision rule) had

A. W. Dooley

1984-01-01

59

Application of PERALS™ alpha spectrometry and gamma spectrometry for analysis and investigation of environmental spills at ISL uranium mining projects.  

PubMed

Radiation protection and environmental monitoring in mining requires effective and reliable radionuclide analysis at all stages of the mine project-prior to mining, during operation and through to remediation and decommissioning. The approach presented in this paper was specially developed for the monitoring of radioactive waste resulting from spills during mining and mineral processing operations and uses a combination of high resolution gamma spectrometry, and PERALS™ alpha spectrometry to identify and reliably quantify the activity of the major members of the U-238 decay chain at activities down to 10 mBq g(-1) by direct radionuclide counting and by assessment of the activity of their decay products. This approach has reduced sample preparation and analysis time while providing effective analysis and quantification of naturally occurring radionuclides in environmental samples. It has been successfully applied to several in situ leach (ISL) mining-related projects involving investigations of process material spill impacts and also to routine environmental monitoring. PMID:24270399

Borysenko, A; Ostrowski, A; Bellifemine, D; Palmer, G; Haigh, P; Johnston, A

2014-03-01

60

NOTE: Measurement and calculation of characteristic prompt gamma ray spectra emitted during proton irradiation  

NASA Astrophysics Data System (ADS)

In this paper, we present results of initial measurements and calculations of prompt gamma ray spectra (produced by proton-nucleus interactions) emitted from tissue equivalent phantoms during irradiations with proton beams. Measurements of prompt gamma ray spectra were made using a high-purity germanium detector shielded either with lead (passive shielding), or a Compton suppression system (active shielding). Calculations of the spectra were performed using a model of both the passive and active shielding experimental setups developed using the Geant4 Monte Carlo toolkit. From the measured spectra it was shown that it is possible to distinguish the characteristic emission lines from the major elemental constituent atoms (C, O, Ca) in the irradiated phantoms during delivery of proton doses similar to those delivered during patient treatment. Also, the Monte Carlo spectra were found to be in very good agreement with the measured spectra providing an initial validation of our model for use in further studies of prompt gamma ray emission during proton therapy.

Polf, J. C.; Peterson, S.; McCleskey, M.; Roeder, B. T.; Spiridon, A.; Beddar, S.; Trache, L.

2009-11-01

61

Measurement and calculation of characteristic prompt gamma ray spectra emitted during proton irradiation.  

PubMed

In this paper, we present results of initial measurements and calculations of prompt gamma ray spectra (produced by proton-nucleus interactions) emitted from tissue equivalent phantoms during irradiations with proton beams. Measurements of prompt gamma ray spectra were made using a high-purity germanium detector shielded either with lead (passive shielding), or a Compton suppression system (active shielding). Calculations of the spectra were performed using a model of both the passive and active shielding experimental setups developed using the Geant4 Monte Carlo toolkit. From the measured spectra it was shown that it is possible to distinguish the characteristic emission lines from the major elemental constituent atoms (C, O, Ca) in the irradiated phantoms during delivery of proton doses similar to those delivered during patient treatment. Also, the Monte Carlo spectra were found to be in very good agreement with the measured spectra providing an initial validation of our model for use in further studies of prompt gamma ray emission during proton therapy. PMID:19864704

Polf, J C; Peterson, S; McCleskey, M; Roeder, B T; Spiridon, A; Beddar, S; Trache, L

2009-11-21

62

Gamma spectrometry and calibration methods used in neutron dosimetry  

Microsoft Academic Search

Neutron activation rates are calculated from measured gamma-ray spectral data obtained from calibrated lithium drifted germanium (Ge(Li)) detectors. The calibration techniques, which include energy, efficiency, pulse height analyzer data reduction, and geometry factors, are discussed. Problems encountered when analyzing highly radioactive samples, specifically random coincidence summing, sample size, air absorption, and use of absorbers, are also discussed briefly. To illustrate

R. L. Malewicki; R. R. Heinrich; R. J. Popek

1979-01-01

63

Intercomparison of efficiency transfer software for gamma-ray spectrometry  

Microsoft Academic Search

The EUROMET project 428 examines efficiency transfer results for Ge gamma-ray spectrometers when the efficiency is known for a reference point source geometry. For this, different methods are used, such as Monte Carlo simulation or semi-empirical computation. The exercise compares the application of these methods to the same selected experimental cases to determine the usage limitations versus the requested accuracy.

M. C. Lépy; T. Altzitzoglou; D. Arnold; F. Bronson; R. Capote Noy; M. Décombaz; F. De Corte; R. Edelmaier; E. Herrera Peraza; S. Klemola; M. Korun; M. Kralik; H. Neder; J. Plagnard; S. Pommé; J. de Sanoit; O. Sima; F. Ugletveit; L. Van Velzen; T. Vidmar

2001-01-01

64

Principal component analysis of low resolution energy spectra to identify gamma sources in moving vehicle traffic  

NASA Astrophysics Data System (ADS)

A system intended to detect, classify, and track radioactive sources in moving vehicle traffic is under development at Lawrence Livermore National Laboratory (LLNL). This system will fuse information from a network of sensor suites to provide real time tracking of the location of vehicles emitting gamma and/or neutron radiation. This work examined aspects of the source terms of interest and applicable gamma detection technologies for passive detection of emitted gamma radiation. The severe restriction placed on the length of count due to motion of the source is presented. Legitimate gamma sources expected in traffic are discussed. The requirement to accurately classify and discriminate against these "nuisance" sources and cost restraints dictate the choice of NaI(Tl) detectors for this application. The development of a capability to automatically analyze short duration, low signal-to-noise NaI(Tl) spectra collected from vehicles passing a large, stationary detector is reported. The analysis must reliably discriminate between sources commonly transported in motor vehicles and alert on the presence of sources of interest. A library of NaI(Tl) spectra for 33 gamma emitting sources was generated with MCNP4B Monte Carlo modeling. These simulated spectra were used as parent distributions, from which multiple realizations of short duration spectra were sampled. Principal component analysis (PCA) of this data set yielded eigenvectors that enable the conversion of unknown spectra into principal component space (PCS). An algorithm using least squares fitting of the positions of library sources in PCS as basis functions, capable of identifying library nuclides in unidentified spectra, is reported. Analysis results for experimental spectra are compared against those achieved using simulated spectra. A valuable characteristic of this method is its ability to identify sources despite unknown shielding geometries. The successful identification of radionuclides and false identification rates found were excellent for the signal levels involved. For many of the sources, identification performance against experimental spectra was somewhat poorer than found using simulated spectra. The results demonstrate that the PCA-based algorithm is capable of high success rates in identifying sources in short duration, low signal-to-noise NaI(Tl) spectra.

Keillor, Martin Eugene

2000-10-01

65

Calculation of neutron and gamma ray energy spectra for fusion reactor shield design: comparison with experiment  

Microsoft Academic Search

Integral experiments that measure the transport of approx. 14 MeV D-T neutrons through laminated slabs of proposed fusion reactor shield materials have been carried out. Measured and calculated neutron and gamma ray energy spectra are compared as a function of the thickness and composition of stainless steel type 304, borated polyethylene, and Hevimet (a tungsten alloy), and as a function

R. T. Santoro; R. G. Jr. Alsmiller; J. M. Barnes; G. T. Chapman

1980-01-01

66

LEAST-SQUARES RESOLUTION OF GAMMA-RAY SPECTRA IN ENVIRONMENTAL SAMPLES  

EPA Science Inventory

The use of ALPHA-M, a least squares computer program for analyzing NaI (Tl) gamma spectra of environmental samples, is evaluated. Included is a comprehensive set of program instructions, listings, and flowcharts. Two other programs, GEN4 and SIMSPEC, are also described. GEN4 is u...

67

On line gamma-ray spectrometry at open sea.  

PubMed

Set up and application of a stationary monitoring network for measuring specific gamma- activities in the Aegean Sea are described. Three NaI scintillator based spectrometers have been used to detect the gamma rays. The gross counting rate of each system was found to be nearly constant, when there was no rainfall. The volumetric activity of the natural gamma-ray emitter 40K in open sea varied from 12,200 to 13,000 Bq/m3. The counting rate for 1461 keV 40K radiation was measured by intercalibration with an appropriate salinity sensor mounted close to the NaI-detector system. A simple relation between the counting rate and the salt concentration has been observed. The amount of the artificial radioactivity from 137Cs was increased up to seven times higher after strong rainfall, compared to the radiation level as given in literature (3.5-5.5 Bq/m3), while the 214Bi counting rate was increased up to ten times compared to the data without rainfall. PMID:15498689

Tsabaris, C; Ballas, D

2005-01-01

68

Application of in-situ gamma spectrometry in the remediation of radioactively contaminated soil  

SciTech Connect

The Fernald Environmental Management Project (FEMP) is a US Department of Energy site that is undergoing total remediation and closure. Most of the remediation effort entails massive excavation of soil for disposal, both offsite and onsite, at an engineered disposal facility. In-situ gamma spectrometry is routinely used to support soil excavation operations to accurately and quickly identify soil areas as being above or below regulatory remediation criteria. Two different in-situ gamma spectrometry systems are used. The first is a sodium iodide (NaI) detector mounted either on a tractor or a jogging stroller, depending on the terrain to be measured. The NaI system allows the collection of a gamma energy spectrum which can be analyzed to identify and quantify radioactive isotopes which are present within the detector`s viewing area. Each energy spectrum is tagged by location coordinates provided by an on-board global positioning system (GPS) to precisely locate elevated contamination areas. The second is a tripod-mounted, high purity germanium detector (HPGe) gamma spectrometry system that is functionally similar to the NaI system. The principal advantage of the HPGe is its superior resolution, which allows much more accurate identification and quantification of radionuclide contaminants in soils. In order to effectively utilize the data quality objective process with these systems, three quality assurance (QA) elements had to be performed.

Sutton, C.; Yesso, J.D.; Danahy, R.J.; Cox, T.

1999-06-01

69

Effects of Compton scattering on the Gamma Ray Spectra of Solar flares  

E-print Network

Using fully relativistic GEANT4 simulation tool kit, the transport of energetic electrons generated in solar flares was Monte-Carlo simulated, and resultant bremsstrahlung gamma-ray spectra were calculated. The solar atmosphere was approximated by 10 vertically-stacked zones. The simulation took into account two important physical processes,that the bremsstrahlung photons emitted by precipitating relativistic electrons are strongly forward beamed toward the photosphere, and that the majority of these gamma-rays must be Compton back-scattered by the solar atmosphere in order to reach the observer. Then, the Compton degradation was found to make the observable gamma-ray spectra much softer than is predicted by simple analytic calculations. The gamma-ray signals were found to be enhanced by several conditions, including a broad pitch-angle distribution of the electrons, a near-limb flare longitude, and a significant tilt in the magnetic field lines if the flare longitude is rather small. These results successfully explain several important flare properties observed in the hard X-ray to gamma-ray range, including in particular those obtained with Yohkoh. A comparison of the Yohkoh spectrum from a GOES X3.7 class limb flare on 1998 November 22, with a simulation assuming a broad electron pitch-angle distribution, suggests that gamma-rays from this particular solar flare were a mixture of direct bremsstrahlung photons and their Comptonization.

Jun'ichi Kotoku; Kazuo Makishima; Yukari Matsumoto; Mitsuhiro Kohama; Yukikatsu Terada; Toru Tamagawa

2007-08-01

70

ON WEAK REDSHIFT DEPENDENCE OF GAMMA-RAY SPECTRA OF DISTANT BLAZARS  

SciTech Connect

Line-of-sight interactions of cosmic rays provide a natural explanation of the hard gamma-ray spectra of distant blazars, which are believed to be capable of producing both gamma rays and cosmic rays. For sources with redshifts z {approx}> 0.1, secondary gamma rays produced in cosmic-ray interactions with background photons close to an observer can dominate over primary gamma rays originating at the source. The transition from one component to another is accompanied by a change in the spectral index depending on the source redshift. We present theoretical predictions and show that they agree with the data from Fermi Large Area Telescope. This agreement, combined with the spectral data from Atmospheric Cherenkov Telescopes, provides evidence of cosmic-ray acceleration by active galactic nuclei and opens new opportunities for studying photon backgrounds and intergalactic magnetic fields.

Essey, Warren [International Center for Computer Science, University of California, Berkeley, CA 94720 (United States); Kusenko, Alexander [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States)

2012-05-20

71

Investigation of Failed TRISO Fuel Assay Using Gamma-Ray Spectrometry  

NASA Astrophysics Data System (ADS)

TRISO microsphere fuel is the fundamental fuel unit for Very High Temperature Reactors (VHTR). A single TRISO particle consists of an inner kernel of Uranium Oxycarbide surrounded by layers of pyrolytic carbon and silicon carbide. The silicon carbide serves as the primary barrier to the release of fission products into the core. If the silicon carbide layer fails, fission gas, especially Kr and Xe, will begin to escape the failed particle. In order to understand the behavior of TRISO fuel under in-core conditions, a series of experiments is being conducted by Idaho National Lab at the Advanced Test Reactor. AGR-1 is the first of these experiments. It will measure fission product release due to failed TRISO particles. Simulations of this experiment have been conducted at North Carolina State University to develop a method for the analysis of the results of the experiment. The ATR core was simulated using the Monte Carlo code MCNP to calculate the expected neutron energy spectrum for the AGR-1 experimental test train. This spectrum was used to create one-group cross sections for implementation in ORIGEN calculations of the amount of activity produced in the experiment. Several theoretical models have been developed to describe the phenomenon of gas release. While each model is based on similar physics, different models contain unique features that distinguish them from one another. These Release to Birth (R/B) models are developed and applied to the activity found in the ORIGEN calculations to create expected release activities. The release activity is used to create gamma-ray spectra that are representative of the different R/B models. Expected R/B due to a model can be calculated for comparison to the experiment with knowledge of the number of failed particles in the spectra. The comparison of measured to predicted R/B ratios gives insight into the physics of release and also helps validate specific models. Direct comparison is possible, but many of the uncertainties associated with direct comparison are nullified through the use of relative indicators. Each R/B model has a unique set of indicators that reflect the physical processes simulated in the model. Trends in the model indicators can be matched up with trends in indicators derived from the release spectra to validate either an entire model or validate the need to consider certain parameters in the creation of a complete and successful release to birth model. Gamma spectrometry is a useful tool for the understanding of fission gas release from failed TRISO particles. A better understanding of the processes that influence fission gas release will influence the fuel manufacturing and quality assurance protocols during the continued development of the VHTR. Future work in this area includes experiment in which the conditions can be better controlled to document the effects of temperature and fission rate in the fuel.

Harp, Jason Michael

72

Similarity analysis of spectra obtained via reflectance spectrometry in legal medicine.  

PubMed

In the present study, a series of reflectance spectra of postmortem lividity, pallor, and putrefaction-affected skin for 195 investigated cases in the course of cooling down the corpse has been collected. The reflectance spectrometric measurements were stored together with their respective metadata in a MySQL database. The latter has been managed via a scientific information repository. We propose similarity measures and a criterion of similarity that capture similar spectra recorded at corpse skin. We systematically clustered reflectance spectra from the database as well as their metadata, such as case number, age, sex, skin temperature, duration of cooling, and postmortem time, with respect to the given criterion of similarity. Altogether, more than 500 reflectance spectra have been pairwisely compared. The measures that have been used to compare a pair of reflectance curve samples include the Euclidean distance between curves and the Euclidean distance between derivatives of the functions represented by the reflectance curves at the same wavelengths in the spectral range of visible light between 380 and 750 nm. For each case, using the recorded reflectance curves and the similarity criterion, the postmortem time interval during which a characteristic change in the shape of reflectance spectrum takes place is estimated. The latter is carried out via a software package composed of Java, Python, and MatLab scripts that query the MySQL database. We show that in legal medicine, matching and clustering of reflectance curves obtained by means of reflectance spectrometry with respect to a given criterion of similarity can be used to estimate the postmortem interval. PMID:23897013

Belenki, Liudmila; Sterzik, Vera; Bohnert, Michael

2014-02-01

73

Simulation of gamma-ray spectra for a variety of user-specified detector designs  

NASA Technical Reports Server (NTRS)

The gamma-ray spectrum simulation program BSIMUL was designed to allow the operator to follow the path of a gamma-ray through a detector, shield and collimator whose dimensions are entered by the operator. It can also be used to simulate spectra that would be generated by a detector. Several improvements have been made to the program within the last few months. The detector, shield and collimator dimensions can now be entered through an interactive menu whose options are discussed below. In addition, spectra containing more than one gamma-ray energy can now be generated with the menu - for isotopes listed in the program. Adding isotopes to the main routine is also quite easy. Subroutines have been added to enable the operator to specify the material and dimensions of a collimator. This report details the progress made in simulating gamma-ray spectra for a variety of user-specified detector designs. In addition, a short discussion of work done in the related areas of pulse shape analysis and the spectral analysis is included. The pulse shape analysis and spectral analysis work is being performed pursuant to the requirements of contract F-94-C-0006, for the Advanced Research Projects Agency and the U.S. Air Force.

Rester, A. C., Jr.

1994-01-01

74

Anomaly Detection in Gamma-Ray Vehicle Spectra with Principal Components Analysis and Mahalanobis Distances  

SciTech Connect

The goal of primary radiation monitoring in support of routine screening and emergency response is to detect characteristics in vehicle radiation signatures that indicate the presence of potential threats. Two conceptual approaches to analyzing gamma-ray spectra for threat detection are isotope identification and anomaly detection. While isotope identification is the time-honored method, an emerging technique is anomaly detection that uses benign vehicle gamma ray signatures to define an expectation of the radiation signature for vehicles that do not pose a threat. Newly acquired spectra are then compared to this expectation using statistical criteria that reflect acceptable false alarm rates and probabilities of detection. The gamma-ray spectra analyzed here were collected at a U.S. land Port of Entry (POE) using a NaI-based radiation portal monitor (RPM). The raw data were analyzed to develop a benign vehicle expectation by decimating the original pulse-height channels to 35 energy bins, extracting composite variables via principal components analysis (PCA), and estimating statistically weighted distances from the mean vehicle spectrum with the mahalanobis distance (MD) metric. This paper reviews the methods used to establish the anomaly identification criteria and presents a systematic analysis of the response of the combined PCA and MD algorithm to modeled mono-energetic gamma-ray sources.

Tardiff, Mark F.; Runkle, Robert C.; Anderson, K. K.; Smith, L. E.

2006-01-23

75

Well Ge and semi-planar Ge (HP) detectors for low-level gamma-spectrometry  

NASA Astrophysics Data System (ADS)

Two gamma spectrometers, a well Ge and a semi-planar Ge (HP), are now installed and calibrated for measurements of environmental radioactivity with special attention being paid to the requirements needed for aquatic mass-balance studies, including isotope-particle dynamics and dating of recent deposits. These facilities will complement the previously developed isotope dilution alpha spectrometry (PIPS detectors) and radon emanation (ionization chambers) techniques for 210Pb dating. A careful evaluation of efficiencies and background of the Ge detectors, together with the influence of the sample's intrinsic activity on the lower limit of detection (LLD), allowed us to study the relative importance of detector and shield specifications on low level gamma spectrometry of environmental samples with various sizes and composition.

El-Daoushy, F.; Garcia-Tenorio, R.

1995-02-01

76

Magnetic properties and Mössbauer spectra of gamma ferric oxide and doped gamma ferric oxide  

Microsoft Academic Search

Magnetic hysteresis, Mössbauer spectra and temperature variation of initial magnetic susceptibility of thirteen samples of doped ?-Fe2O3 containing cobalt or gadolinium are determined. The samples containing more than 1.0% cobalt are found to have a multi-domain configuration, and undoped ?-Fe2O3, gadolinium-doped ?-Fe2O3 and doped ?-Fe2O3 containing less than 1.0% (except 0.3%) cobalt have a single domain configuration. Mössbauer spectra of

A. K. Nikumbh; Ganesh Khind

1990-01-01

77

gamma. -ray spectrometry for determination of radium-228 and radium-226 in natural waters  

Microsoft Academic Search

A technique has been developed for the measurement of ²²⁸Ra and ²²⁶Ra in both fresh- and seawater using Ge(Li) ..gamma..-ray spectrometry. Radium isotopes are preconcentrated in the field from 100 to 1000 L onto Mn-impregnated acrylic fiber cartridges, leached from the fiber and coprecipitated with BaSOâ. Lower limits of detection are controlled by the volume of water processed through the

Jacqueline. Michel; Willard S. Moore; Philip T. King

1981-01-01

78

Determination of plutonium in nuclear materials with the combination of alpha and gamma spectrometry  

NASA Astrophysics Data System (ADS)

Alpha-particle spectrometry (AS) and high-resolution gamma spectrometry (HRGS) are jointly used for the determination of plutonium concentration in various materials containing this element. With AS the alpha activity ratios of 238Pu/( 239Pu + 240Pu) in spiked and unspiked samples and with HRGS the isotopic composition of plutonium in unspiked samples have been measured. The plutonium concentrations are calculated from the isotope dilution formula and are compared with the results from isotope dilution mass spectrometry (IDMS). The relative differences between the results of both methods are within ± 1%. Several factors such as the quality of alpha sources, sample size and the errors in HRGS affect the results and they are discussed in detail.

Parus, J. L.; Raab, W.

1996-02-01

79

MCNPX evaluation of gamma spectrometry results in high radon concentration areas.  

PubMed

The radon concentration in underground workplaces may reach tens of thousands of Bq m(-3). A simple MCNPXTM Monte Carlo (MC) model of a cave was developed to estimate the influence of radon on the in situ gamma spectrometry results in various geometries and radon concentrations. The detector total count rate was obtained as the sum of the individual count rates due to 214Bi in the air, radon in the walls and deposition of radon daughters on surfaces. The MC model was then modified and used in the natural conditions of the Mlade? Caves, Czech Republic. The content of 226Ra was calculated from laboratory gamma spectrometry measurements, and the concentrations of unattached and attached 214Bi were measured using the FRITRA4 device (SMM-Prague). We present a comparison of the experimental results with results calculated by the MCNPXTM model of the Gamma Surveyor spectrometry probe (GF Instruments) with a 3?×3? NaI(Tl) detector and a 2?×2? BGO detector. PMID:24729561

Thinová, L; Solc, J

2014-07-01

80

Inclusive gamma-ray spectra from psi/3095/ and psi-prime/3684/ decays  

NASA Technical Reports Server (NTRS)

Inclusive gamma-ray experiments were carried out in a e(+)e(-) colliding-beam apparatus with NaI(Tl) arrays as detectors. The inclusive gamma-ray spectra, after cosmic-ray background subtraction, are shown as histograms for the decays of the psi(3095) and psi-prime(3684). The psi spectrum has no significant narrow structure, while the psi-prime spectrum shows at least four peaks. Three major radiative decays of the psi-prime(3684) are found, and their respective branching fractions are computed.

Biddick, C. J.; Burnett, T. H.; Masek, G. E.; Miller, E. S.; Smith, J. G.; Stronski, J. P.; Sullivan, M. K.; Vernon, W.; Badtke, D. H.; Barnett, B. A.

1977-01-01

81

Evaluation of TASTEX task H: measurement of plutonium isotopic abundances by gamma-ray spectrometry  

SciTech Connect

This report describes a computer-based gamma spectrometer system that was developed for measuring isotopic and total plutonium concentrations in nitric acid solutions. The system was installed at the Tokai reprocessing plant where it is undergoing testing and evaluation as part of the Tokai Advanced Safeguards Exercise (TASTEX). Objectives of TASTEX Task H, High-Resolution Gamma Spectrometer for Plutonium Isotopic Analysis, the methods and equipment used, the installation and calibration of the system, and the measurements obtained from several reprocessing campaigns are discussed and described. In general, we find that measurements for gamma spectroscopy agree well with those of mass spectrometry and of other chemical analysis. The system measures both freshly processed plutonium from the product accountability tank and aged plutonium solutions from storage tanks. 14 figures, 15 tables.

Gunnink, R.; Prindle, A.L.; Asakura, Y.; Masui, J.; Ishiguro, N.; Kawasaki, A.; Kataoka, S.

1981-10-01

82

Extragalactic background light absorption signal in the TeV gamma-ray spectra of blazars  

Microsoft Academic Search

Recent observations of the TeV gamma-ray spectra of the two closest active galactic nuclei (AGNs), Markarian 501 (Mrk 501) and Markarian 421 (Mrk 421), by the Whipple and HEGRA collaborations have stimulated efforts to estimate or limit the spectral energy density (SED) of extragalactic background light (EBL) which causes attenuation of TeV photons via pair-production when they travel cosmological distances.

V. V. Vassiliev

2000-01-01

83

Measurements of the Martian Gamma/Neutron Spectra with MSL/RAD  

NASA Astrophysics Data System (ADS)

The Radiation Assessment Detector (RAD) onboard Mars Science Laboratory's rover curiosity measures the energetic charged and neutral particle spectra and the radiation dose rate on the Martian surface. An important factor for determining the biological impact of the Martian surface radiation is the specific contribution of neutrons, which possess a high biological effectiveness. In contrast to charged particles, neutrons and gamma rays are generally only measured indirectly. Their measurement is the result of a complex convolution of the incident particle spectrum with the measurement process. We apply an inversion method to calculate the gamma/neutron spectra from the RAD neutral particle measurements. Here we show first measurements of the Martian gamma/neutron spectra and compare them to theoretical predictions. We find that the shape of the gamma spectrum is very similar to the predicted one, but with a ~50% higher intensity. The measured neutron spectrum agrees well with prediction up to ~100 MeV, but shows a considerably increased intensity for higher energies. The measured neutron spectrum translates into a radiation dose rate of 25 ?Gy/day and a dose equivalent rate of 106 ?Sv/day. This corresponds to 10% of the total surface dose rate, and 15% of the biological relevant surface dose equivalent rate on Mars. Measuring the Martian neutron spectra is an essential step for determining the mutagenic influences to past or present life at or beneath the Martian surface as well as the radiation hazard for future human exploration, including the shielding design of a potential habitat. The contribution of neutrons to the dose equivalent increases considerably with shielding thickness, so our measurements provide an important figure to mitigate cancer risk.

Kohler, J.; Zeitlin, C. J.; Ehresmann, B.; Wimmer-Schweingruber, R. F.; Hassler, D.; Reitz, G.; Brinza, D.; Weigle, E.; Boettcher, S.; Burmeister, S.; Guo, J.; Martin-Garcia, C.; Boehm, E.; Posner, A.; Rafkin, S. C.; Kortmann, O.

2013-12-01

84

Gamma ray spectra and sensitivities for 14 MeV neutron activation analysis  

Microsoft Academic Search

The purpose of this study was to define experimentally the sensitivity of determination for 63 different elements by 14 MeV\\u000a neutron activation, with a 150 kV Cockroft-Walton accelerator at a neutron flux of 2·108 n·cm?2·sec?1 on the sample. The obtained gamma ray spectra are given, and the origin of the photopeaks observed are explained. A maximum\\u000a irradiation time of five

M. Cuypers; J. Cuypers

1968-01-01

85

Phase-averaged gamma-ray spectra from rotation-powered millisecond pulsars  

NASA Astrophysics Data System (ADS)

Fermi Large Area Telescope (LAT) has detected pulsed gamma-ray emissions with high confidences from more than 40 millisecond pulsars (MSPs). Here we study the phase-averaged gamma-ray properties of MSPs by using revised version of a self-consistent outer gap model. In this model, a strong multipole magnetic field near the stellar surface for an MSP is assumed and such a field will be close to the surface magnetic fields (˜1011-1012 G) of young pulsars; the outer gap of an MSP is controlled by photon-photon pair production process, where the effects of magnetic inclination angle (?) and magnetic geometry have been taken into account. Therefore, the fractional size of the outer gap is a function of not only pulsar's period and magnetic field strength but also magnetic inclination angle and radial distance to the neutron star; the inner boundary of the outer gap can be estimated by the pair production process of the gamma-ray photons which are produced by the back-flowing particles through the null charge surface; inside the outer gap, a Gaussian distribution of the parallel electric field along the trans-field thickness is assumed, and the gamma-ray emission is represented by the emission from the average radial distance along the central field lines of the outer gap. Using this model, the phase-averaged gamma-ray spectra are calculated and compared with the observed spectra of 37 MSPs given by the second Fermi-LAT catalogue of gamma-ray pulsars; our results show that the Fermi-LAT results can be well explained by this model. The thermal X-ray emission properties from MSPs are also investigated.

Jiang, Z. J.; Chen, S. B.; Li, X.; Zhang, L.

2014-01-01

86

A Case Study Correlating Innovative Gamma Ray Scanning Detection Systems Data to Surface Soil Gamma Spectrometry Results - 13580  

SciTech Connect

HydroGeoLogic (HGL), Inc. completed a United States Environmental Protection Agency (USEPA) study to characterize radiological contamination at a site near Canoga Park, California. The characterized area contained 470 acres including the site of a prototype commercial nuclear reactor and other nuclear design, testing, and support operations from the 1950's until 1988 [1]. The site history included radiological releases during operation followed by D and D activities. The characterization was conducted under an accelerated schedule and the results will support the project remediation. The project has a rigorous cleanup to background agenda and does not allow for comparison to risk-based guidelines. To target soil sample locations, multiple lines of evidence were evaluated including a gamma radiation survey, geophysical surveys, historical site assessment, aerial photographs, and former worker interviews. Due to the time since production and decay, the primary gamma emitting radionuclide remaining is cesium-137 (Cs-137). The gamma ray survey covered diverse, rugged terrain using custom designed sodium iodide thallium-activated (NaI(Tl)) scintillation detection systems. The survey goals included attaining 100% ground surface coverage and detecting gamma radiation as sensitively as possible. The effectiveness of innovative gamma ray detection systems was tested by correlating field Cs-137 static count ratios to Cs-137 laboratory gamma spectrometry results. As a case study, the area encompassing the former location of the first nuclear power station in the U. S. was scanned, and second by second global positioning system (GPS)-linked gamma spectral data were evaluated by examining total count rate and nuclide-specific regions of interest. To compensate for Compton scattering from higher energy naturally occurring radionuclides (U-238, Th-232 and their progeny, and K-40), count rate ratios of anthropogenic nuclide-specific regions of interest to the total count rate were calculated. From the scanning data, locations with observed Cs-137 ratios exceeding six standard deviations above the mean ratio were mapped in high resolution [2]. Field teams returned to those locations to collect static count measurements using the same detection systems. Soil surface samples were collected at 30 locations and analyzed for Cs-137. An exponential correlation was identified between Cs-137 concentrations in surface soil and field-scanned Cs-137 ratios. The data indicate field minimum detectable concentration (MDC) of Cs-137 at 0.02 Bq/g (0.5 pCi/g) or lower depending on contaminant distribution in soil. (authors)

Thompson, Shannon; Rodriguez, Rene; Billock, Paul [HydroGeoLogic, Inc., 11107 Sunset Hills Road, Suite 400, Reston, VA 20190 (United States)] [HydroGeoLogic, Inc., 11107 Sunset Hills Road, Suite 400, Reston, VA 20190 (United States); Lit, Peter [Nomad Science Group, 7738 Nautilus Shell Street, Las Vegas, NV 89139 (United States)] [Nomad Science Group, 7738 Nautilus Shell Street, Las Vegas, NV 89139 (United States)

2013-07-01

87

Measurements of keV-neutron Capture Cross Sections and Capture Gamma-ray Spectra of Pd Isotopes  

NASA Astrophysics Data System (ADS)

The capture cross sections and capture gamma-ray spectra of 104,105,106,108,110Pd were measured in the neutron energy region from 15 to 100 keV. A neutron time-of-flight method was utilized by means of an anti-Compton NaI(Tl) spectrometer and a 1.5 nsec pulsed neutron source via the 7Li(p,n)7Be reaction. The capture yields were obtained by applying a pulse-height weighting technique to the net gamma-ray pulse-height spectra. The capture cross sections of 104,105,106,108,110Pd were determined with uncertainties of less than 6%, using the standard capture cross sections of 197Au. The capture gamma-ray spectra of 104,105,106,108,110Pd were also derived by unfolding the respective observed capture gamma-ray pulse-height spectra.

Terada, K.; Matsuhashi, T.; Hales, B.; Katabuchi, T.; Igashira, M.

2014-05-01

88

The Study of Equilibrium factor between Radon-222 and its Daughters in Bangkok Atmosphere by Gamma-ray Spectrometry  

NASA Astrophysics Data System (ADS)

To study the Equilibrium between radon-222 and its daughters in Bangkok atmosphere by Gamma-ray spectrometry, air sample were collected on 48 activated charcoal canister and 360 glass fiber filters by using a high volume jet-air sampler during December 2007 to November 2008.The Spectra of gamma-ray were measured by using a HPGe (Hyper Pure Germanium Detector). In the condition of secular equilibrium obtaining between Radon-222 and its decay products, radon-222 on activated charcoal canister and its daughters on glass fiber filters collected in the same time interval were calculated. The equilibrium factor (F) in the open air had a value of 0.38 at the minimum ,and 0.75 at the maximum. The average value of equilibrium factor (F) was 0.56±0.12. Based on the results, F had variations with a maximum value in the night to the early morning and decreased in the afternoon. In addition, F was higher in the winter than in the summer. This finding corresponds with the properties of the Earth atmosphere. The equilibrium factor (F) also depended on the concentration of dust in the atmosphere. People living in Bangkok were exposed to average value of 30 Bq/m3 of Radon-222 in the atmosphere. The equilibrium factor (0.56±0.12) and the average value of Radon-222 showed that people were exposed to alpha energy from radon-222 and its daughters decay at 0.005 WL(Working Level) which is lower than the safety standard at 0.02 WL. Keywords: Radon, Radon daughters , equilibrium factor, Gamma -ray spectrum analysis ,Bangkok ,Thailand

Rujiwarodom, Rachanee

2010-05-01

89

In situ gamma spectrometry of piping in a CANDU heat transport system -- Application during decontamination  

SciTech Connect

An in situ pipe gamma spectrometry technique was applied to determine the activity within piping during various stages of CANDU reactor decontaminations. Measurements were performed in general radiation fields up to {approximately}500 mR/h and required both the detector and the pipe being scanned to be appropriately shielded from other neighboring piping. Measured counts were interpreted using a pipe source efficiency calibration with due regard to its distance dependence. Cobalt-60 was the dominant radionuclide on the piping before the decontamination. Deposition of {sup 124}Sb occurred on out-core piping surfaces during the decontamination. The spectrometry measurements were supplemented with contact radiation field measurements, which were performed using survey detectors housed within specially designed pipe shields. Radiation fields estimated from measured radionuclide activities were compared with the measured radiation fields. On average, the ratio of measured to estimated fields was {approximately}72%. Reasons for this discrepancy are discussed.

Husain, A.; Breckenridge, C.E. [Ontario Hydro Technologies, Toronto, Ontario (Canada); Storey, D. [Ontario Hydro Nuclear, Toronto, Ontario (Canada)

1995-02-01

90

Experimental and MCNP simulated gamma-ray spectra for the UNCOSS neutron-based explosive detector  

NASA Astrophysics Data System (ADS)

In the frame of the FP7 UNCOSS project (Underwater Coastal Sea Surveyor), whose aim is to develop a neutron-based explosive detection system to identify unexploded ordnance (UXO) lying on the sea bottom, the choice of the gamma-ray detector is essential to reach the optimal performances. This paper presents comparative tests between the two candidates: NaI(Tl) and LaBr 3(Ce) detectors, in favour to the 3 in.×3 in. LaBr 3(Ce); thus, confirming the choice previously performed by numerical simulation because of its higher fast timing properties, spectral resolution, and efficiency per volume unit. The gamma-ray spectra produced by 14 MeV tagged neutron beams on the elements of interest (C, O, N, Al, Fe, Si, and Ca) have also been recorded with this detector in order to unfold the spectrum of the interrogated object into elementary contributions. A qualitative comparison with the gamma-ray spectra simulated with the MCNPX computer code and the ENDFB/VII.0 nuclear library has also been performed to validate the numerical model. An additional quantitative validation has been performed with an explosive-like material (ammonium acetate).

Eleon, C.; Perot, B.; Carasco, C.; Sudac, D.; Obhodas, J.; Valkovic, V.

2011-02-01

91

A convenient method for discriminating between natural and depleted uranium by gamma-ray spectrometry.  

PubMed

A convenient method for discriminating between natural and depleted uranium reagent was developed by measuring and analyzing the gamma-ray spectra of some reagents with no standard source. The counting rates (R) of photoelectric peaks of gamma-rays from nuclides with the same radioactivity divided by their emission probability (B) are expressed as a function of gamma-ray energy. The radioactivities of 234Th and 234mPa and 21.72 times that of 235U are equal to the radioactivity of 235U in natural uranium. Therefore, the plot of 21.72-fold R/B for 235U should be on a curve fitted to the points for 234Th and 234mPa in natural uranium. Depleted uranium with a 235U isotopic composition of less than 0.68% could be discriminated from natural uranium in the case of a reagent containing 4.0 g of uranium. PMID:11393763

Shoji, M; Hamajima, Y; Takatsuka, K; Honoki, H; Nakajima, T; Kondo, T; Nakanishi, T

2001-08-01

92

Measuring the radium quartet (228Ra, 226Ra, 224Ra, 223Ra) in seawater samples using gamma spectrometry.  

PubMed

Radium isotopes are widely used in marine studies (eg. to trace water masses, to quantify mixing processes or to study submarine groundwater discharge). While 228Ra and 226Ra are usually measured using gamma spectrometry, short-lived Ra isotopes (224Ra and 223Ra) are usually measured using a Radium Delayed Coincidence Counter (RaDeCC). Here we show that the four radium isotopes can be analyzed using gamma spectrometry. We report 226Ra, 228Ra, 224Ra, 223Ra activities measured using low-background gamma spectrometry in standard samples, in water samples collected in the vicinity of our laboratory (La Palme and Vaccarès lagoons, France) but also in seawater samples collected in the plume of the Amazon river, off French Guyana (AMANDES project). The 223Ra and 224Ra activities determined in these samples using gamma spectrometry were compared to the activities determined using RaDeCC. Activities determined using the two techniques are in good agreement. Uncertainties associated with the 224Ra activities are similar for the two techniques. RaDeCC is more sensitive for the detection of low 223Ra activities. Gamma spectrometry thus constitutes an alternate method for the determination of short-lived Ra isotopes. PMID:20106569

van Beek, P; Souhaut, M; Reyss, J-L

2010-07-01

93

Contribution of atmospherical radon to in-situ scintillation gamma spectrometry data.  

PubMed

In-situ gamma spectrometry can be used for monitoring and determining natural and man-made radionuclide concentrations in the environment. The low detection limit of potential contaminants depends on the natural background variations, including variations in the atmospheric concentrations of radon and its decay products. The scintillation spectrometer response for atmospheric radon was simulated by the Monte Carlo method, and the results were compared with the experimental measurements over large water surfaces. The contributions of atmospheric radon to the natural background were assessed. PMID:21129988

Kluso?, J; Thinová, L

2011-08-01

94

Radioactivity measurements in the aquatic environment using in-situ and laboratory gamma-ray spectrometry.  

PubMed

The in-situ underwater gamma-ray spectrometry method is validated by inter-comparison with laboratory method. Deployments of the spectrometer KATERINA on a submarine spring and laboratory measurements of water samples with HPGe detector were performed. Efficiency calibrations, Monte Carlo simulations and the Minimum Detectable Activity (MDA) estimations were realized. MDAs varied from 0.19 to 10.4 (lab) and 0.05 to 0.35 (in-situ) Bq/L, while activity concentrations differed from 7% (for radon progenies) up to 10% (for (40)K), between the two methods. PMID:24103707

Eleftheriou, G; Tsabaris, C; Androulakaki, E G; Patiris, D L; Kokkoris, M; Kalfas, C A; Vlastou, R

2013-12-01

95

Nuclear chemistry of returned lunar samples: Nuclide analysis by gamma-ray spectrometry  

NASA Technical Reports Server (NTRS)

Primordial and cosmogenic radionuclide concentrations are determined nondestructively by gamma-ray spectrometry in soil and rock samples from the returned Apollo 17 sample collection from Taurus-Littrow and Descartes. Geochemical evidence in support of field geology speculation concerning layering of the subfloor basalt flows is demonstrated along with a possible correlation of magmatic fractionation of K/U as a function of depth. The pattern of radionuclide concentrations observed in these samples is distinct due to proton bombardment by the intense solar flares of August 4-9, 1972. Such radionuclide determinations are used in determining lunar sample orientation and characterizing solar flare activity.

Okelley, G. D.

1975-01-01

96

Technologically enhanced levels of natural radioactivity studied by gamma-ray spectrometry  

NASA Astrophysics Data System (ADS)

The pollution of the environment arising from sources emitting preconcentrated natural radionuclides was studied using low-level gamma-spectrometry. Along the upper stream of the river Sava in Slovenia (Yugoslavia) many sources with enhanced concentrations of natural radionuclides contribute to the pollution of the river. The pollution of air is usually limited to the vicinity of the sources. A planar Ge(HP) detector with a large surface showed improved sensitivity for 210Pb, U, and Ra in comparison to the 116 cm 3 Ge(Li) coaxial detector.

Brajnik, D.; Kobal, I.; Korun, M.; Miklavži?, U.

1986-11-01

97

Superluminal cascade spectra of TeV {gamma}-ray sources  

SciTech Connect

Astrophysical radiation sources are scrutinized in search of superluminal {gamma}-rays. The tachyonic spectral densities generated by ultra-relativistic electrons in uniform motion are fitted to the high-energy spectra of Galactic supernova remnants, such as RX J0852.0-4622 and the pulsar wind nebulae in G0.9+0.1 and MSH 15-52. The superluminal spectral maps of the unidentified TeV {gamma}-ray sources HESS J1303-631, TeV J2032+4130 and HESS J1825-137 are inferred from EGRET, HEGRA and HESS data. Tachyonic cascade spectra are quite capable of generating the spectral curvature seen in double-logarithmic plots, as well as the extended spectral plateaus defined by EGRET flux points in the GeV band. The curvature of the TeV spectra is intrinsic, caused by the Boltzmann factor in the source densities. The spectral averaging with thermal and exponentially cut power-law electron densities can be done in closed form, and systematic high- and low-temperature expansions of the superluminal spectral densities are derived. Estimates on the electron/proton populations generating the tachyon flux are obtained from the spectral fits, such as power-law indices, temperature and source counts. The cutoff temperatures of the source densities suggest ultra-high-energy protons in MSH 15-52, HESS J1825-137 and TeV J2032+4130.

Tomaschitz, Roman [Department of Physics, Hiroshima University, 1-3-1 Kagami-yama, Higashi-Hiroshima 739-8526 (Japan)]. E-mail: tom@geminga.org

2007-03-15

98

GEANT4 Calibration of Gamma Spectrometry Efficiency for Measurements of Airborne Radioactivity on Filter Paper.  

PubMed

A simple method of efficiency calibration for gamma spectrometry was performed. This method, which focused on measuring airborne radioactivity collected on filter paper, was based on Monte Carlo simulations using the toolkit GEANT4. Experimentally, the efficiency values of an HPGe detector were calculated for a multi-gamma disk source. These efficiency values were compared to their counterparts produced by a computer code that simulated experimental conditions. Such comparison revealed biases of 24, 10, 1, 3, 7, and 3% for the radionuclides (photon energies in keV) of Ce (166), Sn (392), Cs (662), Co (1,173), Co (1,333), and Y (1,836), respectively. The output of the simulation code was in acceptable agreement with the experimental findings, thus validating the proposed method. PMID:25271933

Alrefae, Tareq

2014-11-01

99

Radioactivity Levels and Gamma-Ray Dose Rate in Soil Samples from Kohistan (Pakistan) Using Gamma-Ray Spectrometry  

NASA Astrophysics Data System (ADS)

The analysis of naturally occurring radionuclides (226Ra, 232Th and 40K) and an anthropogenic radionuclide 137Cs is carried out in some soil samples collected from Kohistan district of N.W.F.P. (Pakistan), using gamma-ray spectrometry. The gamma spectrometry is operated using a high purity Germanium (HPGe) detector coupled with a computer based high resolution multi channel analyzer. The specific activity in soil ranges from 24.72 to 78.48Bq·kg-1 for 226Ra, 21.73 to 75.28Bq·kg-1 for 232Th, 7.06 to 14.9Bq·kg-1 for 137Cs and 298.46 to 570.77Bq·kg-1 for 40K with the mean values of 42.11, 43.27, 9.5 and 418.27Bq·kg-1, respectively. The radium equivalent activity in all the soil samples is lower than the safe limit set in the OECD report (370Bq·kg-1). Man-made radionuclide 137Cs is also present in detectable amount in all soil samples. Presence of 137Cs indicates that the samples in this remote area also receive some fallout from nuclear accident in Chernobyl power plant in 1986. The internal and external hazard indices have the mean values of 0.48 and 0.37 respectively. Absorbed dose rates and effective dose equivalents are also determined for the samples. The concentration of radionuclides found in the soil samples during the present study is nominal and does not pose any potential health hazard to the general public.

Hasan, M. Khan; Ismail, M.; K., Khan; Akhter, P.

2011-01-01

100

Hints of the existence of axionlike particles from the gamma-ray spectra of cosmological sources  

SciTech Connect

Axionlike particles (ALPs) are predicted to couple with photons in the presence of magnetic fields. This effect may lead to a significant change in the observed spectra of gamma-ray sources such as active galactic nuclei (AGNs). Here we carry out a detailed study that for the first time simultaneously considers in the same framework both the photon/axion mixing that takes place in the gamma-ray source and that one expected to occur in the intergalactic magnetic fields. An efficient photon/axion mixing in the source always means an attenuation in the photon flux, whereas the mixing in the intergalactic medium may result in a decrement and/or enhancement of the photon flux, depending on the distance of the source and the energy considered. Interestingly, we find that decreasing the value of the intergalactic magnetic field strength, which decreases the probability for photon/axion mixing, could result in an increase of the expected photon flux at Earth if the source is far enough. We also find a 30% attenuation in the intensity spectrum of distant sources, which occurs at an energy that only depends on the properties of the ALPs and the intensity of the intergalactic magnetic field, and thus independent of the AGN source being observed. Moreover, we show that this mechanism can easily explain recent puzzles in the spectra of distant gamma-ray sources, like the possible detection of TeV photons from 3C 66A (a source located at z=0.444) by MAGIC and VERITAS, which should not happen according to conventional models of photon propagation over cosmological distances. Another puzzle is the recent published lower limit to the extragalactic background light intensity at 3.6 {mu}m (which is almost twice larger as the previous one), which implies very hard spectra for some detected TeV gamma-ray sources located at z=0.1-0.2. The consequences that come from this work are testable with the current generation of gamma-ray instruments, namely Fermi (formerly known as GLAST) and imaging atmospheric Cherenkov telescopes like CANGAROO, HESS, MAGIC, and VERITAS.

Sanchez-Conde, M. A.; Prada, F. [Instituto de Astrofisica de Andalucia (CSIC), E-18008, Granada (Spain); Paneque, D.; Bloom, E. [Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), SLAC National Accelerator Center, Sand Hill Road 2575, Menlo Park, California 94025 (United States); Dominguez, A. [Instituto de Astrofisica de Andalucia (CSIC), E-18008, Granada (Spain); Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla, E-41012, Sevilla (Spain)

2009-06-15

101

VAXGAP: A code for the routine analysis of gamma-ray pulse-height spectra on a VAX computer  

SciTech Connect

VAXGAP (VAX Gamma-ray Analysis Package) is a collection of computer programs for the analysis of pulse height spectra acquired on Ge detector-based spectrometers. VAXGAP was written to provide the operators of a radiation measurements laboratory with the necessary software tools for routine analysis of radioactive samples through the analysis of gamma-ray pulse-height spectra. A detailed description of the algorithms used in VAXGAP is presented elsewhere. This paper summarizes the unique features and the organization of VAXGAP which makes it of particular value in the routine analysis of spectra. 1 ref., 3 figs., 1 tab.

Killian, E.W.; Hartwell, J.K.

1988-01-01

102

Models for the Transition Regions of gamma Draconis and Capella based on Hubble GHRS Spectra  

NASA Astrophysics Data System (ADS)

We have analyzed Goddard High Resolution Spectrometer observations of the hybrid-chromosphere star gamma Draconis (K5 III) and the long-period RS CVn system alpha Aurigae (Capella, G8 III + G0 III) observed at phase 0.26. Here we discuss the low resolution spectra obtained with the G140L grating that cover the 1057--1943 Angstroms region for gamma Dra and the 1161--1710 Angstroms region for Capella. We identify the emission lines and tabulate their observed fluxes and surface fluxes. Assuming that most of the emission line flux from Capella is produced by the G0 III star, we find that the surface fluxes of the transition region lines are typically 400 times larger than for the Sun and only a factor of 4 below the saturation limit. By contrast, the surface fluxes of the transition region lines for gamma Dra are a factor of 40 times smaller than for the Sun and are the smallest values ever detected for a star. We have derived models for the transition regions of gamma Dra and the Capella G0 III star covering the temperature range 20,000--150,000 K by an emission measure analysis of the emission line surface fluxes. One interpretation of the gamma Dra model is that the high-temperature material occurs in magnetically heated active regions that cover ~ 10(-4) by area of the surface. Another interpretation is that the very small amount of hot material occurs in a few very strong shock waves that can occur when there is a stochastic distribution of acoustic wave periods. This work is supported by NASA Interagency Transfer S-56500-D to the National Institute of Standards and Technology. (1) Staff member, Quantum Physics Division, National Institute of Standards and Technology.

Linsky, J. L.; Andrulis, C.; Brown, A.

1992-12-01

103

Cyclotron resonant scattering in the spectra of gamma-ray bursts  

NASA Technical Reports Server (NTRS)

Fits of theoretical spectra from Monte Carlo radiation-transfer calculations to dips at approximately 20 and 40 keV in a spectrum of the gamma-ray burst source GB 880 205 give best-fit values and 68 percent-confidence intervals for the magnetic field of (1.71 + or - 0.07) x 10 to the 12th G, the electron density of (1.2 + or - 0.6) x 10 to the 21st electrons/cm-squared, and the cosine of the viewing angle relative to the field of 0.31 + or - 0.05. The dips observed at approximately 20 keV in the spectra are interpreted as cyclotron resonant scattering, in which electrons undergo radiative 0 to 1 to 0 Landau transitions initiated by photons near the first harmonic. Physical self-consistency fixes the temperature, and the equilibrium temperature equals 5.3 + 0.3 or - 0.2 keV. These results suggest that this gamma-ray burst and many others which exhibit a low-energy dip originate from strongly magnetic neutron stars and are galactic in origin.

Wang, J. C. L.; Lamb, D. Q.; Loredo, T. J.; Wasserman, I. M.; Salpeter, E. E.

1989-01-01

104

Gamma-ray spectra of methane in the positron-electron annihilation process  

E-print Network

Bound electron contribution to the Doppler-shift of gamma-ray spectra in the positron-electron annihilation process of molecular methane has been studied in gas phase. Two accurate ab initio quantum mechanical schemes, i.e. the delocalized molecular orbital (MO) and the localized natural bond orbital (NBO) schemes, are applied to study the multi-centred methane molecule. The present ab initio calculations of methane indicate that the C-H bonds are polarized with the partial negative charge of -0.36 a.u. on the carbon atom and the partial positive charge of +0.09 a.u. on each of the hydrogen atoms. The positively charged hydrogen atoms produce repulsive Coulomb potentials to a positron. Both the MO and NBO schemes further reveal that the 2a1 electrons of methane, that is, the 2a1 electron component of the C-H bonds rather than the whole C-H bonds of methane, predominates the positron-electron annihilation gamma-ray spectra of the molecule. Electrons of a molecule which are dominant the positron-electron annihi...

Ma, Xiaoguang

2012-01-01

105

Gamma-ray spectra of methane in the positron-electron annihilation process  

E-print Network

Bound electron contribution to the Doppler-shift of gamma-ray spectra in the positron-electron annihilation process of molecular methane has been studied in gas phase. Two accurate ab initio quantum mechanical schemes, i.e. the delocalized molecular orbital (MO) and the localized natural bond orbital (NBO) schemes, are applied to study the multi-centred methane molecule. The present ab initio calculations of methane indicate that the C-H bonds are polarized with the partial negative charge of -0.36 a.u. on the carbon atom and the partial positive charge of +0.09 a.u. on each of the hydrogen atoms. The positively charged hydrogen atoms produce repulsive Coulomb potentials to a positron. Both the MO and NBO schemes further reveal that the 2a1 electrons of methane, that is, the 2a1 electron component of the C-H bonds rather than the whole C-H bonds of methane, predominates the positron-electron annihilation gamma-ray spectra of the molecule. Electrons of a molecule which are dominant the positron-electron annihilation processes are called positrophilic electrons in the present study. It is further shown that the negative electrostatic potential (ESP) of methane facilitates with the density of the positrophilic 2a1 electrons of methane. Other valence electrons (e.g. 1t2) in the C-H bonds play a minor spectator role in the annihilation process of methane.

Xiaoguang Ma; Feng Wang

2012-11-02

106

Spectra  

NSDL National Science Digital Library

Learners construct a spectroscope out of a shoe box or mailing tube, diffraction grating, and other simple materials. They then use their spectroscope to observe spectra, the colors that make up light. Learners compare the spectra of various light sources. Use this activity to introduce learners to basic principles of light and color. Also, look at a related page about auroras to understand how distinguishing spectra of different atoms helps scientists understand the universe.

Exploratorium, The

2012-06-26

107

Spectra  

NSDL National Science Digital Library

Spectra is a very informative website about how astronomers use spectra to understand what stars are made of, their structures, and their evolution. The page begins with an introduction to the electromagnetic spectrum and then goes into great detail about the properties of light. Then it talks about how matter both creates and destroys radiation. Then it discusses how to interpret absorption and emission lines. The website ends with how astronomers use spectra to understand stars, galaxies, other objects in the universe.

Kaler, James

2004-07-16

108

Examination of level density prescriptions in the interpretation of high energy gamma-ray spectra  

E-print Network

High energy $\\gamma$-ray spectra measured by our group involving the compound nuclei (CN) $^{63}$Cu at excitation energy ($E^*$) $\\sim$ 36 MeV with average angular momentum ($J$) = 12 - 17 $\\hbar$, $^{97}$Tc at $E^* \\sim$ 29 - 50 MeV with $J$ = 12 - 14 $\\hbar$, $^{113}$Sb at $E^*$ = 109 MeV and 121 MeV with $J$ = 49 - 59 $\\hbar$ and $^{201}$Tl at $E^*$ = 39.5, 47.5 MeV with $J$ = 18 - 24 $\\hbar$ have been analyzed utilizing the level density prescriptions of (i)Ignatyuk, Smirenkin and Tishin (IST), (ii)Budtz-Jorgensen and Knitter (BJK), and (iii) Kataria, Ramamurthy and Kapoor (KRK). These three prescriptions have been tested for correct statistical model description of high energy $\\gamma$-rays in the light of extracting the giant dipole resonance (GDR) parameters at low excitation energy and spin where shell effects might play an important role as well as at high excitation energy where shell effects have melted. Interestingly, only the IST level density prescription could explain the high energy $\\gamma$-r...

Bhattacharya, Srijit; Dey, Balaram; Mondal, Debasish; Mukhopadhyay, S; Pal, Surajit; De, A; Banerjee, S R

2014-01-01

109

Low-level gamma spectrometry for pollution assessment in San Simón Bay (Vigo, Spain)  

NASA Astrophysics Data System (ADS)

A gamma spectrometer with HPGe detector of 50% relative efficiency and 1 cps total background has been dedicated to the measurement of an intertidal sediment core from a coastal environment at the Ría de Vigo (Spain). The area is affected by lead pollution and the source identification needs of a precise dating of the sediment core. Such a precise dating requires the measurement not only of the radionuclides directly involved in time calculation, as 210Pb and 226Ra, but also of ancillary radionuclides which inform about the dating model to apply and about the validity of its time estimation. Gamma spectrometry with Ge detectors performs a simultaneous measurement of the full content in ?-emitters of the sample. However, its use is limited by its high spectral background. We present the characteristics of our lowlevel background gamma spectrometer and also of Galea, the computing tool for the expert analysis of natural radionuclides. Both make possible to get the proper experimental results to reach a suitable dating. The results allowed us to detect a change in the sedimentation dynamics in the area under study, to verify the impact of lead pollution in the 210Pb level, to obtain a sedimentation rate by using the CF:CS model with a suitable correction factor and, finally, to validate the sediment dating.

Quintana, B.; Álvarez-Iglesias, P.; Santamaría, R.; Rubio, B.; Pérez-Arlucea, M.

2006-05-01

110

The time evolution of GRB spectra by a precessing lighthouse $\\gamma$ jet  

E-print Network

Inverse Compton Scattering (ICS) by a relativistic electron beam jet at GeV energies (emitted by a compact object as a NS, BH,...), a NSJ, onto thermal BBR photons (from a nearby stellar companion) may originate a collinear gamma jet (GJ). Due to the binary system interaction the GJ precession would blaze suddenly toward the observer leading to a GRB event. The internal GJ cone structure is ruled by relativistic kinematics into a concentric onion-like sequence of photon rings, the softer in the external boundaries, the harder in the inner cone. The pointing and the crossing of such different GJ photon rings to the detector lead to a GRB hardness spectra evolution nearly corresponding to most observed ones. Moreover expected time integral spectra are also comparable with known GRB spectra. The total energy input of tens of thousands of such NSJ in an extended galactic halo, mainly cosmic rays electrons, should be reflected into the recent observational evidence (COMPTEL) of a diffused relic extended halo. Evid...

Fargion, D

1996-01-01

111

Examination of Count-starved Gamma Spectra Using the Method of Spectral Comparison Ratios  

SciTech Connect

We discuss the determination of energy bin boundaries and decision metrics for gamma-ray spectra, acquired using a mid-resolution detector, that are useful in the detection of illicit sources at low total counts. The bins are designed to produce the lowest minimum detectable counts (MDC) using a spectral comparison ratio technique at a given false positive rate, for a specified population of benign-source spectra. Spectra from the benign source population consist of observations taken by a detector on a moving vehicle, as would be obtained during a search for a missing or hidden source. Raw counts in bins are transformed into a vector of background-corrected count differences. Bin boundaries are determined to yield large values of a standardized length of this vector for benign-plus-benchmark sources by the application of an optimization technique. The objective function includes penalties for overlap with the spectral features of naturally occurring radioactive materials. We compare estimated MDC values for such bins applied to depleted uranium and barium-133 sources with those based on gross counting, and we examine the effect of nuisance potassium-, radium- and thorium-dominated sources. We demonstrate that, using this methodology, energy bins may be designed for sensitivity to special nuclear materials, improving the likelihood of detection in low-count or masked-source searches.

Pfund, David M.; Runkle, Robert C.; Anderson, Kevin K.; Jarman, Kenneth D.

2007-08-01

112

The time evolution of GRB spectra by a precessing lighthouse Gamma Jet  

E-print Network

Inverse Compton Scattering (ICS) by a relativistic electron beam jet at GeV energies (emitted by a compact object as a NS, BH,...), a NSJ, onto thermal BBR photons (from a nearby stellar companion) may originate a collinear gamma jet (GJ). Due to the binary system interaction the GJ precession would blaze suddenly toward the observer leading to a GRB event. The internal GJ cone structure is ruled by relativistic kinematics into a concentric onion-like sequence of photon rings, the softer in the external boundaries, the harder in the inner cone. The pointing and the crossing of such different GJ photon rings to the detector lead to a GRB hardness spectra evolution nearly corresponding to most observed ones. Moreover expected time integral spectra are also comparable with known GRB spectra. The total energy input of tens of thousands of such NSJ in an extended galactic halo, mainly cosmic rays electrons, should be reflected into the recent observational evidence (COMPTEL) of a diffused relic extended halo. Evidences of such precessing jets are offered by the discover of galactic superluminal sources, recent HH jets, SN1987A outer rings, Hourglass Nebula, planetary Egg Nebula, GROJ1744-28 binary X-rays pulsar.

D. Fargion; A. Salis

1996-05-28

113

Radon fixation for determination of 224Ra, 226Ra and 228Ra via gamma-ray spectrometry  

Microsoft Academic Search

The aim of this work is the improvement of the procedure for the determination of radium isotopes activities in water, which is done through radiochemical separation and subsequent gamma-ray spectrometry. In addition, radon gas retention is studied using different activated carbon materials. The results of the IAEA Proficiency test: “Determination of radium and uranium radionuclides in water” of December 2002

M. Herranz; R. Idoeta; A. Abelairas; F. Legarda

2006-01-01

114

Spectra of X-ray and Gamma-ray Bursts Produced by Stepping Lightning Leaders  

NASA Astrophysics Data System (ADS)

Terrestrial gamma-ray flashes (TGFs) are bursts of high-energy photons originating from the Earth's atmosphere in association with thunderstorm activity. TGFs were serendipitously discovered by BATSE detector aboard the Compton Gamma-Ray Observatory originally launched to perform observations of celestial gamma-ray sources [Fishman et al., Science, 264, 1313, 1994]. These events have also been detected by the RHESSI satellite [Smith et al., Science, 307, 1085, 2005], the AGILE satellite [Marisaldi et al., JGR, 115, A00E13, 2010], and the Fermi Gamma-ray Space Telescope [Briggs et al., JGR, 115, A07323, 2010]. Moreover, measurements have correlated TGFs with initial development stages of normal polarity intra-cloud lightning that transports negative charge upward (+IC) [e.g, Lu et al., JGR, 116, A03316, 2011]. Photon spectra corresponding to well-established model of relativistic runaway electron avalanches (RREAs) usually provide a very good agreement with satellite observations [Dwyer and Smith, GRL, 32, L22804, 2005]. However, it has been suggested that high-potential +IC lightning leaders could produce a sufficient number of energetic electrons to explain TGFs [Celestin and Pasko, JGR, 116, A03315, 2011] and Xu et al. [GRL, 39, L08801, 2012] have shown that this mechanism could explain the TGF spectrum for lightning potentials higher than 100 MV. In addition to TGFs, X-ray bursts are produced by negative lightning leaders in association with stepping processes and are observed from the ground [Dwyer et al., GRL, 32, L01803, 2005]. However, the energy spectrum of X-ray bursts from lightning is still poorly known, mainly due to the low fluence detected from the ground. In this work, we use Monte Carlo models to study the acceleration of runaway electrons in the electric field produced around lightning leader tip and the associated bremsstrahlung photon spectra observed by low-orbit satellites in the case of high potential +IC discharges and from the ground in the case of negative cloud-to-ground discharges. We particularly investigate the variability of the photon spectrum with the lightning electric potential.

Celestin, Sebastien; Xu, Wei; Pasko, Victor

2013-04-01

115

Use of HPGe gamma-ray spectrometry to assess the isotopic compositiion of uranium in soils.  

PubMed

Gamma-ray spectrometry was used to determine uranium activity and investigate the presence of depleted uranium in soil samples collected from camping sites of the Greek expeditionary force in Kosovo. Assessment of 238U concentrations was based on measurements of the 63.3 keV and 92.38 keV emissions of its first daughter nuclide, 234Th. To determine the isotopic ratio of 238U/235U, secular equilibrium along the two radioactive series was first ensured and thereby the contribution of 235U under the 186 keV peak was deduced. The uranium activity in the samples varied from 48 to 112 Bq kg(-1), whereas the activity ratio of 238U/235U averaged 23.1+/-4.3. PMID:12500805

Papachristodoulou, C A; Assimakopoulos, P A; Patronis, N E; Ioannides, K G

2003-01-01

116

Optical and FTIR spectra of NdF3-doped borophosphate glasses and effect of gamma irradiation  

NASA Astrophysics Data System (ADS)

UV-visible, FTIR absorption spectra of some prepared undoped and NdF3-doped borophosphate glasses with varying dopant contents were studied before and after gamma irradiation. The base undoped borophosphate glass exhibits strong UV absorption which is related to the presence of unavoidable trace iron impurities within the chemicals used for the preparation of such glass. NdF3-doped samples show characteristic bands specifically at high concentration which are attributed to the Nd3+ ions. Gamma irradiation on the undoped borophosphate glass causes no obvious induced defects. On the other hand, the low NdF3 content glass produces extended UV absorption together with the resolution of an extra induced visible at about 500 nm. On increasing the NdF3 content, gamma irradiation retains the characteristic bands due to Nd3+ ions. Infrared absorption spectra of undoped and NdF3-doped glasses reveal characteristic IR vibrational bands due to the combination of both phosphate and borate groups (BO3 and BO4) with the first phosphate partner dominating in response to the high percent (50 mol%). The introduction of NdF3 within the dopant level (1.5-6%) produces no distinct effect on the FTIR spectra. Gamma irradiation is observed to cause no obvious effects on the FTIR spectra which is related to the stability of mixed phosphate and borate units causing the compactness and resistance towards gamma irradiation.

ElBatal, F. H.; Ibrahim, S.; Abdelghany, A. M.

2012-12-01

117

Standardization of 222Rn by LSC and comparison with alpha- and gamma-spectrometry.  

PubMed

Liquid scintillation counting (LSC) was used for the measurement of 222Rn in equilibrium with its daughters, with detection efficiency close to 5. The appropriate corrections were considered, including one related to the probability that the 165-micros half-life 214Po decays during the dead time of the counter initiated by the disintegration of his parent nuclide, 214Bi. The dead-time determination of a commercial LS counter is also presented using a 222Rn standard source. The LSC 222Rn sources were prepared by transfer of 222Rn produced by a solid 226Ra source into LSC cocktail frozen at 77K, flame-sealed afterwards. They were measured using the LNHB triple coincidence counter with adjustable extending-type dead-time unit, between 8 and 100 micros; two different procedures were used to calculate an effective dead time and then to deduce the counting rate extrapolated to zero dead-time value. The LSC results were compared with those obtained by cryogenic alpha-particle spectrometry (LNHB system) and by gamma-ray spectrometry for the same radon source in the LSC vial; the geometry transfer coefficient was calculated using the ETNA software. Measurement results and uncertainties are discussed. PMID:16876423

Cassette, P; Sahagia, M; Grigorescu, L; Lépy, M C; Picolo, J L

2006-01-01

118

Effective absorbing column density in the gamma-ray burst afterglow X-ray spectra  

E-print Network

We investigate the scaling relation between the observed amount of absorption in the X-ray spectra of Gamma Ray Burst (GRB) afterglows and the absorber redshift. Through dedicated numerical simulations of an ideal instrument, we establish that this dependence has a power law shape with index 2.4. However, for real instruments, this value depends on their low energy cut-off, spectral resolution and on the detector spectral response in general. We thus provide appropriate scaling laws for specific instruments. Finally, we discuss the possibility to measure the absorber redshift from X-ray data alone. We find that 10^5-10^6 counts in the 0.3-10 keV band are needed to constrain the redshift with 10% accuracy. As a test case we discuss the XMM-Newton observation of GRB 090618 at z=0.54. We are able to recover the correct redshift of this burst with the expected accuracy.

Campana, S; Braito, V; Cusumano, G; D'Avanzo, P; D'Elia, V; Ghirlanda, G; Ghisellini, G; Melandri, A; Salvaterra, R; Tagliaferri, G; Vergani, S D

2014-01-01

119

GRABGAM: A Gamma Analysis Code for Ultra-Low-Level HPGe SPECTRA  

SciTech Connect

The GRABGAM code has been developed for analysis of ultra-low-level HPGe gamma spectra. The code employs three different size filters for the peak search, where the largest filter provides best sensitivity for identifying low-level peaks and the smallest filter has the best resolution for distinguishing peaks within a multiplet. GRABGAM basically generates an integral probability F-function for each singlet or multiplet peak analysis, bypassing the usual peak fitting analysis for a differential f-function probability model. Because F is defined by the peak data, statistical limitations for peak fitting are avoided; however, the F-function does provide generic values for peak centroid, full width at half maximum, and tail that are consistent with a Gaussian formalism. GRABGAM has successfully analyzed over 10,000 customer samples, and it interfaces with a variety of supplementary codes for deriving detector efficiencies, backgrounds, and quality checks.

Winn, W.G.

1999-07-28

120

Effective absorbing column density in the gamma-ray burst afterglow X-ray spectra  

NASA Astrophysics Data System (ADS)

We investigate the scaling relation between the observed amount of absorption in the X-ray spectra of gamma-ray burst afterglows and the absorber redshift. Through dedicated numerical simulations of an ideal instrument, we establish that this dependence has a power-law shape with index 2.4. However, for real instruments, this value depends on their low-energy cut-off, spectral resolution and on the detector spectral response in general. We thus provide appropriate scaling laws for specific instruments. Finally, we discuss the possibility to measure the absorber redshift from X-ray data alone. We find that 105-106 counts in the 0.3-10 keV band are needed to constrain the redshift with 10 per cent accuracy. As a test case, we discuss the XMM-Newton observation of GRB 090618 at z = 0.54. We are able to recover the correct redshift of this burst with the expected accuracy.

Campana, S.; Bernardini, M. G.; Braito, V.; Cusumano, G.; D'Avanzo, P.; D'Elia, V.; Ghirlanda, G.; Ghisellini, G.; Melandri, A.; Salvaterra, R.; Tagliaferri, G.; Vergani, S. D.

2014-07-01

121

Investigation of the soil-plant transfer of primordial radionuclides in tomatoes by low-level gamma-ray spectrometry.  

PubMed

The paper presents actual data from investigations of the soil-plant transfer of the primordial radionuclides 40K, 238U, 226Ra, 210Pb and 227Ac for tomatoes growing at soils from former uranium mining areas. The analysis were carried out using low-level gamma-ray spectrometry in a 47 m deep underground laboratory. For tomato fruits transfer factors of (0.0007 +/- 0.0006) for 235U, (0.0021 +/- 0.0017) for 226Ra, (0.0015 +/- 0.0009) for 210Pb and (0.0018 +/- 0.0012) for 227Ac were obtained. The investigation of the soil-plant transfer by low-level gamma-ray spectrometry is often limited by the Compton-continuum from the always present high-energy gamma-ray emitter 40K. PMID:10879862

Köhler, M; Gleisberg, B; Niese, S

2000-01-01

122

Performance of UniSampo-Shaman with gamma-ray spectra containing known traces of fission products  

Microsoft Academic Search

A set of 100 gamma-ray spectra with known traces of anthropogenic nuclides was utilized in the First System-Wide Performance\\u000a Test (SPT1) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) in June 2005. The spectrum set was very realistic,\\u000a since it is based on real measured spectra. Yet, the correct spectrum contents are known, when anthropogenic peaks with known\\u000a areas have been

P. A. Aarnio; J. J. Ala-Heikkilä; T. T. Hakulinen

2008-01-01

123

Modeling of Gamma-ray Spectra to Direct Efficient Chemical Separations  

SciTech Connect

In an age of heightened national security regarding nuclear terrorist threats, reliable and rapid analytical methods for the quantification of radionuclides in fission product samples are needed to provide forensic information and sample characterization. Measurement of characteristic gamma-ray emissions by high-purity germanium spectrometers offers one means of analysis. Due to the high-activity and complex nature of samples, chemical separations are necessary to reduce background continuum levels and instances of spectral interference. A project has been initiated at Pacific Northwest National Laboratory (PNNL) to model singles and coincident gamma-ray spectra that would result from various chemical separation strategies. The goal is to use these complementary counting techniques to tailor a series of efficient chemical separations that allow the rapid quantification of signature isotopes in samples. Modeling enables probable instances of spectral interference to be identified and aids in defining the temporal window of detection for radionuclides of interest following a given chemical separation. These data will help future analysts prioritize analytes of interest and separation strategies in the processing of real samples. A description of results to date is described here, demonstrating the utility of this approach for improved processing and analysis of fission product samples.

Douglas, Matthew; Friese, Judah I.; Warren, Glen A.; Bachelor, Paula P.; Farmer, Orville T.; Choiniere, Andrea D.; Schulte, Shannon M.; Aalseth, Craig E.

2008-06-15

124

ON THE X-RAY SPECTRA OF ANOMALOUS X-RAY PULSARS AND SOFT GAMMA REPEATERS  

SciTech Connect

We revisit the apparent correlation between soft X-ray band photon index and spin-down rate {nu}-dot previously reported for Anomalous X-ray Pulsars (AXPs) and Soft Gamma Repeaters (SGRs) by Marsden and White. Our analysis, improved thanks to new source discoveries, better spectral parameter measurements in previously known sources, and the requirement of source quiescence for parameter inclusion, shows evidence for the previously noted trend, although with greater scatter. This trend supports the twisted magnetosphere model of magnetars although the scatter suggests that factors other than {nu}-dot are also important. We also note possible correlations involving the spectra of AXPs and SGRs in the hard X-ray band. Specifically, the hard-band photon index shows a possible correlation with inferred {nu}-dot and B, as does the degree of spectral turnover. If the former trend is correct, then the hard-band photon index for AXP 1E 1048.1 - 5937 should be {approx}0-1. This may be testable with long integrations by the International Gamma-Ray Astrophysics Laboratory, or by the upcoming focusing hard X-ray mission NuSTAR.

Kaspi, V. M.; Boydstun, K. [Department of Physics, Rutherford Physics Building, McGill University, 3600 University Street, Montreal, Quebec, H3A 2T8 (Canada)], E-mail: vkaspi@physics.mcgill.ca

2010-02-20

125

The time evolution of GRB spectra by a precessing lighthouse gamma jet  

NASA Astrophysics Data System (ADS)

Inverse Compton Scattering (ICS) by a relativistic electron beam jet at GeV energies (emitted by a compact object as a NS, BH,...), a NSJ, onto thermal BBR photons (from a nearby stellar companion) may originate a collinear gamma jet (GJ). Due to the binary system interaction the GJ precession would blaze suddenly toward the observer leading to a GRB event. The internal GJ cone structure is ruled by relativistic kinematics into a concentric onion-like sequence of photon rings, the softer in the external boundaries, the harder in the inner cone. The pointing and the crossing of such different GJ photon rings to the detector lead to GRB hardness spectral evolution nearly corresponding to that typically observed. Moreover, the expected time integral spectra are also comparable with observed GRB spectra. The total energy input of tens of thousands of such NSJ in an extended galactic halo, mainly cosmic rays electrons, should be reflected into the recent observational evidence (COMPTEL) of a diffuse relic extended halo. Evidences of such precessing jets are offered by the discovery of galactic superluminal sources, HH jets, the outer rings of SN1987A, the Hourglass Nebula, the planetary Egg Nebula, and the binary X-ray pulsar GROJ1744-28.

Fargion, Daniele; Salis, Andrea

1996-08-01

126

Spectral information enhancement using wavelet-based iterative filtering for in vivo gamma spectrometry.  

PubMed

Use of wavelet transformation in stationary signal processing has been demonstrated for denoising the measured spectra and characterisation of radionuclides in the in vivo monitoring analysis, where difficulties arise due to very low activity level to be estimated in biological systems. The large statistical fluctuations often make the identification of characteristic gammas from radionuclides highly uncertain, particularly when interferences from progenies are also present. A new wavelet-based noise filtering methodology has been developed for better detection of gamma peaks in noisy data. This sequential, iterative filtering method uses the wavelet multi-resolution approach for noise rejection and an inverse transform after soft 'thresholding' over the generated coefficients. Analyses of in vivo monitoring data of (235)U and (238)U were carried out using this method without disturbing the peak position and amplitude while achieving a 3-fold improvement in the signal-to-noise ratio, compared with the original measured spectrum. When compared with other data-filtering techniques, the wavelet-based method shows the best results. PMID:22887117

Paul, Sabyasachi; Sarkar, P K

2013-04-01

127

\\Gamma\\Gamma \\Gamma\\Gamma  

E-print Network

\\Gamma\\Gamma @@@ @@@ ### ### ### ### \\Gamma\\Gamma\\Gamma \\Gamma\\Gamma\\Gamma @@@ @@@ ### ### ### ### \\Gamma\\Gamma\\Gamma \\Gamma\\Gamma\\Gamma yyy yyy \\Gamma\\Gamma@@####\\Gamma\\Gamma@@####\\Gamma\\Gamma@@####\\Gamma\\Gamma@@####\\Gamma\\Gamma@@####\\Gamma\\Gamma\\Gamma @@@ @@@ ### ### ### ### \\Gamma\\Gamma\\Gamma \\Gamma\\Gamma\\Gamma @@@ @@@ ### ### ### ### \\Gamma\\Gamma\\Gamma \\Gamma\\Gamma\\Gamma yyy

Laske, Gabi

128

Impact of secondary acceleration on the neutrino spectra in gamma-ray bursts  

NASA Astrophysics Data System (ADS)

Context. The observation of charged cosmic rays with energies up to 1020 eV shows that particle acceleration must occur in astrophysical sources. Acceleration of secondary particles like muons and pions, produced in cosmic ray interactions, are usually neglected, however, when calculating the flux of neutrinos from cosmic ray interactions. Aims: Here, we discuss the acceleration of secondary muons, pions, and kaons in gamma-ray bursts (GRBs) within the internal shock scenario, and their impact on the neutrino fluxes. Methods: We introduce a two-zone model consisting of an acceleration zone (the shocks) and a radiation zone (the plasma downstream the shocks). The acceleration in the shocks, which is an unavoidable consequence of efficient proton acceleration, requires efficient transport from the radiation back to the acceleration zone. On the other hand, stochastic acceleration in the radiation zone can enhance the secondary spectra of muons and kaons significantly if there is a sufficiently large turbulent region. Results: Overall, it is plausible that neutrino spectra can be enhanced by up to a factor of two at the peak by stochastic acceleration, that an additional spectral peak appears from shock acceleration of the secondary muons and pions, and that the neutrino production from kaon decays is enhanced. Conclusions: Depending on the GRB parameters, the general conclusions concerning the limits to the internal shock scenario obtained by recent IceCube and ANTARES analyses may be affected by up to a factor of two by secondary acceleration. Most of the changes occur at energies above 107 GeV, so the effects for next-generation radio-detection experiments will be more pronounced. In the future, however, if GRBs are detected as high-energy neutrino sources, the detection of one or several pronounced peaks around 106 GeV or higher energies could help to derive the basic properties of the magnetic field strength in the GRB.

Winter, W.; Becker Tjus, J.; Klein, S. R.

2014-09-01

129

Inter-pulse high-resolution gamma-ray spectra using a 14 MeV pulsed neutron generator  

USGS Publications Warehouse

A neutron generator pulsed at 100 s-1 was suspended in an artificial borehole containing a 7.7 metric ton mixture of sand, aragonite, magnetite, sulfur, and salt. Two Ge(HP) gamma-ray detectors were used: one in a borehole sonde, and one at the outside wall of the sample tank opposite the neutron generator target. Gamma-ray spectra were collected by the outside detector during each of 10 discrete time windows during the 10 ms period following the onset of gamma-ray build-up after each neutron burst. The sample was measured first when dry and then when saturated with water. In the dry sample, gamma rays due to inelastic neutron scattering, neutron capture, and decay were counted during the first (150 ??s) time window. Subsequently only capture and decay gamma rays were observed. In the wet sample, only neutron capture and decay gamma rays were observed. Neutron capture gamma rays dominated the spectrum during the period from 150 to 400 ??s after the neutron burst in both samples, but decreased with time much more rapidly in the wet sample. A signal-to-noise-ratio (S/N) analysis indicates that optimum conditions for neutron capture analysis occurred in the 350-800 ??s window. A poor S/N in the first 100-150 ??s is due to a large background continuum during the first time interval. Time gating can be used to enhance gamma-ray spectra, depending on the nuclides in the target material and the reactions needed to produce them, and should improve the sensitivity of in situ well logging. ?? 1984.

Evans, L.G.; Trombka, J.I.; Jensen, D.H.; Stephenson, W.A.; Hoover, R.A.; Mikesell, J.L.; Tanner, A.B.; Senftle, F.E.

1984-01-01

130

Fieldable computer system for determining gamma-ray pulse-height distributions, flux spectra, and dose rates from Little Boy  

SciTech Connect

Our system consists of a LeCroy 3500 data acquisition system with a built-in CAMAC crate and eight bismuth-germanate detectors 7.62 cm in diameter and 7.62 cm long. Gamma-ray pulse-height distributions are acquired simultaneously for up to eight positions. The system was very carefully calibrated and characterized from 0.1 to 8.3 MeV using gamma-ray spectra from a variety of radioactive sources. By fitting the pulse-height distributions from the sources with a function containing 17 parameters, we determined theoretical repsonse functions. We use these response functions to unfold the distributions to obtain flux spectra. A flux-to-dose-rate conversion curve based on the work of Dimbylow and Francis is then used to obtain dose rates. Direct use of measured spectra and flux-to-dose-rate curves to obtain dose rates avoids the errors that can arise from spectrum dependence in simple gamma-ray dosimeter instruments. We present some gamma-ray doses for the Little Boy assembly operated at low power. These results can be used to determine the exposures of the Hiroshima survivors and thus aid in the establishment of radation exposure limits for the nuclear industry.

Moss, C.E.; Lucas, M.C.; Tisinger, E.W.; Hamm, M.E.

1984-01-01

131

F-GAMMA: On the phenomenological classification of continuum radio spectra variability patterns of Fermi blazars  

NASA Astrophysics Data System (ADS)

The F-GAMMA program is a coordinated effort to investigate the physics of Active Galactic Nuclei (AGNs) via multi-frequency monitoring of Fermi blazars. In the current study we show and discuss the evolution of broad-band radio spectra, which are measured at ten frequencies between 2.64 and 142 GHz using the Effelsberg 100-m and the IRAM 30-m telescopes. It is shown that any of the 78 sources studied can be classified in terms of their variability characteristics in merely 5 types of variability. It is argued that these can be attributed to only two classes of variability mechanisms. The first four types are dominated by spectral evolution and can be described by a simple two-component system composed of: (a) a steep quiescent spectral component from a large scale jet and (b) a time evolving flare component following the "Shock-in-Jet" evolutionary path. The fifth type is characterised by an achromatic change of the broad band spectrum, which could be attributed to a different mechanism, likely involving differential Doppler boosting caused by geometrical effects. Here we present the classification, the assumed physical scenario and the results of calculations that have been performed for the spectral evolution of flares.

Angelakis, E.; Fuhrmann, L.; Nestoras, I.; Fromm, C. M.; Perucho-Pla, M.; Schmidt, R.; Zensus, J. A.; Marchili, N.; Krichbaum, T. P.; Ungerechts, H.; Sievers, A.; Riquelme, D.; Pavlidou, V.

2012-07-01

132

Effects induced by gamma-irradiation and thermal treatment on the infrared spectra of ferrocene in its disordered state  

NASA Astrophysics Data System (ADS)

Lattice, rotation and intramolecular vibrations of ferrocene, Fe(C5H5)(2), crystallites of the C-2h(5) factor group in the disordered phase are calculated using the correlation theorem based on group theory. The correlation between the species of the C-1 site symmetry occupied by cyclopentadienyl molecules and those of the factor group C-2h, of the crystal are calculated. The number of lattice vibrations of the cyclopentadienyl molecules is found to be 12. with active modes in Raman and infrared (IR) spectra. The same number of rotations for the cyclopentadienyl molecules is expected to be allowed in both spectra. The active number of intramolecular vibrations for the cyclopentadienyl molecules having D-5 molecular symmetry is expected to be 80 vibrations in both the Raman and the IR spectra. The effect of gamma-irradiation with different doses and heat treatment at different temperatures on the IR spectra of ferrocene in the energy range 4000-200 cm(-1) is discussed. A number of bands continuously shifted their position, and a decrease in intensity with increasing gamma-dose is observed. New bands appeared in this spectral region for different annealing temperatures and different gamma-doses. These changes are discussed in terms of intermolecular interactions between molecules within the unit cell.

Gaffar, M. A.; Abd-Elrahman, M. I.

2004-10-01

133

A NEW METHDOLOGY FOR DETERMINING FISSILE MASS IN INDIVIDUAL ACCOUNTING ITEMS WITH THE USE OF GAMMA-RAY SPECTROMETRY.  

SciTech Connect

In the safeguards, arms control, and nonproliferation regimes measurements are required which give the quantity of fissile material in an accounting item, e.g., a standard container of plutonium or uranium oxide. Because of the complexity of modeling the absorption of gamma rays in high-Z materials, gamma-ray spectrometry is not customarily used for this purpose. Gamma-ray measurements can be used to determine the fissile mass when two conditions are met: (1) The material is in a standard container, and (2) The material is finely divided, or a solid item with a reproducible shape. The methodology consists of: (A) Measurement of the emitted gamma rays, and (B) Measurement of the transmission through the item of the high-energy gamma rays of Co-60 and Th-228. We have demonstrated that items containing nuclear materials possess a characteristic ''fingerprint'' of gamma rays which depends not only on the nuclear properties, but also on the mass, density, shape, etc.. The material's spectrum confirms its integrity, homogeneity, and volume as well. While there is attenuation of radiation from the interior, the residual radiation confirms the homogeneity of the material throughout the volume. Transmission measurements, where the attenuation depends almost entirely on Compton scattering, determine the material mass. With well-characterized standards, this methodology can provide an accurate measure of the contained fissile material.

KANE,W.R.; VANIER,P.E.; ZUHOSKI,P.B.; LEMLEY,J.R.

2000-07-16

134

Thermospray liquid-chromatography mass spectrometry of thiol radioprotective agents: Characteristics spectra. Scientific report  

SciTech Connect

Ethiofos (S-2(3-aminopropylamino)ethylphosphorothioic acid or WR-2721) is currently being evaluated in clinical radiotherapy trials (Kligerman et al., 1980) because of its potential for enhancing the efficacy of radiotherapy (Kligerman et al., 1980; Yuhas and Storer, 1969). For proper drug usage and pharmacological studies, it is necessary to assess the stability of the aminothiol and the presence of impurities or decomposition products. In addition, monitoring the plasma levels of WR-2721 and its metabolites should improve the therapeutic usefulness of WR-2721. Several high-performance liquid chromatography (HPLC) methodologies have been developed that are applicable for routine analysis of aminothiols and endogeneous cellular thiols (Newton et al., 1981; Swynnerton et al., 1984). One of these methodologies, electrochemical detection, permits the simultaneous detection of the free thiol and the disulfides (Swynnerton et al. 1984). Mass spectrometry (MS) is a sensitive technique that can confirm purity and provide useful structural information. Using a thermospray interface, samples can be introduced into the mass spectrometer from a liquid chromatograph (LC) (Vestal, 1984). The interface thermally nebulizes the eluant into a high-pressure region of the mass spectrometer where a variety of soft-ionization techniques may be used to ionize the analyte molecules. The feasibility of LC coupled to MS-detection was studied for the analysis of thiol-containing radioprotective agents, including glutathione, WR-2721, and WR-1065, the dephosphorylated sulfhydryl form of WR-2721, which has been shown to be its active radioprotective metabolite (Calabro-Jones et al., 1983).

Walden, T.L.; Buchner, J.; Pizzitola, V.; Blakeley, W.F.

1988-01-01

135

Cosmic-ray spectra of primary protons and high altitude muons deconvolved from observed atmospheric gamma rays  

E-print Network

We have observed atmospheric gamma rays from 30GeV to 8TeV, using emulsion chambers at balloon altitudes, accumulating the largest total exposure in this energy range to date, SOT ~ 6.66m^2.sr.day. At very high altitudes, with residual overburden only a few g/cm^2, atmospheric gamma rays are mainly produced by a single interaction of primary cosmic rays with overlying atmospheric nuclei. Thus, we can use these gamma rays to study the spectrum of primary cosmic rays and their products in the atmosphere. From the observed atmospheric gamma ray spectrum, we deconvolved the primary cosmic-ray proton spectrum, assuming appropriate hadronic interaction models. Our deconvolved proton spectrum covers the energy range from 200GeV to 50TeV, which fills a gap in the currently available primary cosmic-ray proton spectra. We also estimated the atmospheric muon spectrum above 30GeV at high altitude from our gamma-ray spectrum, almost without reference to the primary cosmic rays, and compared the estimated flux with direct muon observations below 10GeV.

K. Yoshida; R. Ohmori; T. Kobayashi; Y. Komori; Y. Sato; J. Nishimura

2006-09-30

136

Gamma spectra from ²³³U, ²³⁵U, and ²³⁹Pu during thermal neutron irradiation. [Reaction mechanisms not distinguished  

Microsoft Academic Search

The gamma spectra from three fissionable isotopes, ²³³U, ²³⁵U, and ²³⁹Pu, were measured during neutron irradiation in the thermal column of the Omega West Reactor. The measurements were preceded by a neutron irradiation of at least 20,000 s to build up a near-equilibrium concentration of the shorter half-life fission products. The measurements provide the total gamma spectra and do not

P. J. Bendt; E. T. Jurney

1978-01-01

137

Analysis pipeline for air filter gamma-ray spectra from the CTBT verification network  

Microsoft Academic Search

Summary  Some environmental xenon sampling like the Automated Radioxenon Sampler-Analyzer (ARSA) and the Swedish Automated Noble Gas Unit (SAUNA), use &bgr;-&ggr; coincidence detectors that are energy dispersive on both the &ggr; and &bgr; axes. Applying conventional region-of-interest (ROI) analysis algorithms to such 3-D spectra is problematic due to spectral interferences in the low-resolution spectra. Deconvolving the 3-D sample spectra into the

P. A. Aarnio; J. J. Ala-Heikkilä; T. K. Ansaranta; T. T. Hakulinen

2005-01-01

138

Identification of filamentous fungi isolates by MALDI-TOF mass spectrometry: clinical evaluation of an extended reference spectra library.  

PubMed

The identification of filamentous fungi by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) relies mainly on a robust and extensive database of reference spectra. To this end, a large in-house library containing 760 strains and representing 472 species was built and evaluated on 390 clinical isolates by comparing MALDI-TOF MS with the classical identification method based on morphological observations. The use of MALDI-TOF MS resulted in the correct identification of 95.4% of the isolates at species level, without considering LogScore values. Taking into account the Brukers' cutoff value for reliability (LogScore >1.70), 85.6% of the isolates were correctly identified. For a number of isolates, microscopic identification was limited to the genus, resulting in only 61.5% of the isolates correctly identified at species level while the correctness reached 94.6% at genus level. Using this extended in-house database, MALDI-TOF MS thus appears superior to morphology in order to obtain a robust and accurate identification of filamentous fungi. A continuous extension of the library is however necessary to further improve its reliability. Indeed, 15 isolates were still not represented while an additional three isolates were not recognized, probably because of a lack of intraspecific variability of the corresponding species in the database. PMID:25349253

Becker, Pierre T; de Bel, Annelies; Martiny, Delphine; Ranque, Stéphane; Piarroux, Renaud; Cassagne, Carole; Detandt, Monique; Hendrickx, Marijke

2014-11-01

139

Cyclotron resonant scattering in the spectra of gamma-ray bursts  

NASA Technical Reports Server (NTRS)

Data on the GB880205 gamma-ray bursts are presented that have implications for the nature of gamma-ray burst sources. It is shown that cyclotron resonant scattering and Raman scattering account well for the positions, strengths, and shapes of the relative strengths of the first and second harmonics and their narrow widths. These results imply the existence of a superstrong (B of about 2 x 10 to the 12th G) magnetic field in the vicinity of the X-ray emission region of GB880205. Such a superstrong magnetic field points to a strongly magnetic neutron star as the origin of gamma-ray bursts, and to the fact that the gamma-ray sources belong to the Galaxy.

Lamb, D. Q.; Wang, J. C. L.; Loredo, T. J.; Wasserman, I.; Fenimore, E. E.

1989-01-01

140

A Compton filter to improve photopeak intensity evaluation in gamma ray spectra  

Microsoft Academic Search

A procedure for filtering the photopeak intensity from the Compton continuum interference is described. A continuum energy region of up to 0.478 and the 0.662 MeV photopeak are well defined in a cesium-137 theoretical spectrum. The filter was applied to a high intensity Compton region in the gamma spectrum obtained by the attenuation measurements in laboratory experiments. A Cs-137 (gamma=0.662

P. C. L. da Costa; C. C. Dantas; C. A. B. O. Lira; V. A. Dos Santos

2004-01-01

141

Neutron Capture Cross Sections and Gamma Emission Spectra from Neutron Capture on 234,236,238U Measured with DANCE  

NASA Astrophysics Data System (ADS)

A new measurement of the 238U(n, ?) cross section using a thin 48 mg/cm2 target was made using the DANCE detector at LANSCE over the energy range from 10 eV to 500 keV. The results confirm earlier measurements. Measurements of the gamma-ray emission spectra were also made for 238U(n, ?) as well as 234,236U(n, ?). These measurements help to constrain the radiative strength function used in the cross-section calculations.

Ullmann, J. L.; Mosby, S.; Bredeweg, T. A.; Couture, A. J.; Haight, R. C.; Jandel, M.; Kawano, T.; O'Donnell, J. M.; Rundberg, R. S.; Vieira, D. J.; Wilhelmy, J. B.; Wu, C.-Y.; Becker, J. A.; Chyzh, A.; Baramsai, B.; Mitchell, G. E.; Krticka, M.

2014-05-01

142

SINGLE- AND TWO-COMPONENT GAMMA-RAY BURST SPECTRA IN THE FERMI GBM-LAT ENERGY RANGE  

SciTech Connect

Most Fermi gamma-ray burst spectra appear as either a broken power law extending to GeV energies or as a broken power with a separate GeV power-law component. Here we show that such spectra can be understood in terms of magnetically dominated relativistic jets where a dissipative photosphere produces the prompt MeV emission, which is extended into the GeV range by inverse Compton scattering in the external shock, with possible contributions from a reverse shock as well. The bulk Lorentz factors required in these models are in the range of 300-600, and the MeV-GeV time delays arise naturally. In some cases an optical flash and a sub-dominant thermal component are also present.

Veres, P.; Meszaros, P., E-mail: veresp@psu.edu, E-mail: nnp@astro.psu.edu [Department of Astronomy and Astrophysics, Department of Physics, and Center for Particle Astrophysics, 525 Davey Lab., Pennsylvania State University, University Park, PA 16802 (United States)

2012-08-10

143

Rapid analysis of phthalic acid esters in environmental water using fast elution gas chromatography with mass spectrometry and adaptive library spectra.  

PubMed

A method for the fast determination of the components in a complex sample by using gas chromatography with mass spectrometry was developed and used for the quantitative analysis of phthalic acid esters in environmental water. In the method, the adaptively corrected mass spectra were used to compensate for the differences between the library spectra and the measured ones in the experiment. The correction was obtained by the iterative transformation of the library spectra using iterative target transformation factor analysis, and the resolution was performed by non-negative immune algorithm using the corrected spectra. Rapid analysis of 16 phthalic acid esters in water samples was achieved using fast elution gas chromatography with mass spectrometry measurements. The results show that the mass spectra and chromatographic profiles of the phthalic acid esters can be obtained from the overlapping signal of 13 min elution, and accurate quantitative analysis can be obtained. The recoveries of the phthalic acid esters obtained by standard addition are between 90.3 and 107.4%, and the relative standard deviations obtained in repeated measurements are less than 9%. PMID:24737593

Li, Pao; Mei, Zhen; Cai, Wensheng; Shao, Xueguang

2014-07-01

144

Simultaneous determination of Ra and Th nuclides, 238U and 227Ac in uranium mining waters by gamma-ray spectrometry  

PubMed

For the investigation of flooding processes in uranium mines, Ra and Th nuclides as well as 238U and 227Ac activities in waters were simultaneous analyzed by gamma-ray spectrometry. The activities of 227Ac and 228Th, not directly determinable by gamma-ray spectrometry, can be calculated from two consecutive measurements (approximately 25 d delay) of the progeny 227Th and 224Ra. For the short-lived radionuclides 234Th, 227Th, 223Ra and 224Ra a correction of the results to the sampling date is necessary. PMID:10724431

Kohler; Niese; Gleisberg; Jenk; Nindel

2000-03-01

145

Gamma-Ray Spectra of Fission Products observed with Li-Drifted Germanium Detectors, (II)  

Microsoft Academic Search

The ?-ray spectra of short-lived fission products from thermal neutron irradiation of highly enriched U were observed with an encapsulated Li-drifted Ge ?-ray spectrometer. The spectra at various periods—10 min, 30 min, 1,2,5,10 and 20 hr—after irradiation were measured up to about 1 meV. The relative activities of fission products at various periods after irradiation (10 min–20 hr) were calculated

Noboru ?I; Isami TANABE; Yasuyoshi MATSUSHIMA

1967-01-01

146

IR spectra simulation as auxiliary tool for gas chromatography-Fourier transform IR spectroscopy-mass spectrometry identification of unknown compounds: comparison between several semi-empirical methods  

Microsoft Academic Search

A set of the semi-empirical methods supplied by the HyperChem™ package has been tested to find the best auxiliary tool for the gas chromatography-Fourier transform IR spectroscopy-mass spectrometry identification of cyclic amide-type compounds. The method MINDO3 has been found to be the most advantageous since: (1) as a rule, the IR spectra simulated by this method best match the experimental

Vladimir A. Basiuk

1999-01-01

147

Nondestructive and quantitative characterization of TRU and LLW mixed-waste using active and passive gamma-ray spectrometry and computed tomography  

Microsoft Academic Search

The technology being proposed by LLNL is an Active and Passive Computed Tomography (A P CT) Drum Scanner for contact-handled (CH) wastes. It combines the advantages offered by two well-developed nondestructive assay technologies: gamma-ray spectrometry and computed tomography (CT). Coupled together, these two technologies offer to nondestructively and quantitatively characterize mixed- wastes forms. Gamma-ray spectroscopy uses one or more external

D. C. Camp; H. E. Martz

1991-01-01

148

Determination of Vanadium by Instrumental Neutron Activation Analysis in Conjunction with Compton Suppression Gamma-Ray Spectrometry  

SciTech Connect

The toxicity of vanadium has been known for a long time. It is only recently that vanadium has been recognized as an essential trace element. The determination of vanadium with high precision and accuracy in tissues, foods, and other biological materials is needed for the purpose of studying its effect on human nutrition and health. Several techniques such as spectrophotometry, atomic absorption, X-ray fluorescence, and neutron activation analysis (NAA) can be used for its determination. Vanadium can be determined by NAA through its short-lived nuclide {sup 52}V produced via the {sup 51}V(n, {gamma}){sup 52}V reaction; it has a 1434.2-keV gamma ray and a half-life of 3.74 min. It has been reported that {sup 52}V has sufficient sensitivity for its measurement down to nanogram levels. However, it is seldom assayed in practice by instrumental NAA (INAA) in conjunction with conventional gamma-ray spectrometry, in particular for low vanadium content in high-salt biological materials, due to the Compton background interference from nuclides such as {sup 28}Al, {sup 38}Cl, {sup 56}Mn, and {sup 24}Na. Alternatively, radiochemical NAA or preconcentration NAA methods are used to separate vanadium from the major and interfering elements. A Compton suppression counting technique can be beneficially used under such situations. One of the objectives of this work was to fully explore the advantages of Compton suppression counting for the determination of vanadium in biological samples.

W. H. Zhang; A. Chatt

2000-11-12

149

A method for the comparison of performance of gamma-ray spectrometry calibration cocktails.  

PubMed

In order to make quantitative assessments about the usefulness of different gamma-ray emitting radionuclide cocktails to carry out efficiency calibrations of gamma-ray spectrometers, a method has been developed that allows the comparison of their different performances and to optimize the choice of gamma energy lines for the radionuclides within a specific cocktail. The method has been applied to compare different cocktail configurations obtained from measurements made in the laboratory with monoenergetic radionuclides, and their relative performances are presented and discussed. PMID:14987701

Legarda, F; Los Arcos, J M; Herranz, M

2004-01-01

150

The time evolution of GRB spectra by a precessing lighthouse gamma jet  

Microsoft Academic Search

Inverse Compton Scattering (ICS) by a relativistic electron beam jet at GeV energies (emitted by a compact object as a NS, BH,...), a NSJ, onto thermal BBR photons (from a nearby stellar companion) may originate a collinear gamma jet (GJ). Due to the binary system interaction the GJ precession would blaze suddenly toward the observer leading to a GRB event.

Daniele Fargion; Andrea Salis

1996-01-01

151

Toward a More Standardized Candle Using Gamma?Ray Burst Energetics and Spectra  

Microsoft Academic Search

ABSTRACT The use of gamma-ray burst (GRB) energetics for cosmography,has long been advanced as a means to probe out to high redshifts, to the epoch of deceleration. However, although relatively immune tosystematic biases from dust extinction, the prompt energy release in GRBs, even when corrected for jetting geometry, is far from being a standard candle. In this work we explore

Andrew S. Friedman; Joshua S. Bloom

2005-01-01

152

Effect of positron-atom interactions on the annihilation gamma spectra of molecules  

NASA Astrophysics Data System (ADS)

Calculations of ?-spectra for positron annihilation on a selection of molecules, including methane and its fluoro-substitutes, ethane, propane, butane and benzene are presented. The annihilation ?-spectra characterise the momentum distribution of the electron-positron pair at the instant of annihilation. The contribution to the ?-spectra from individual molecular orbitals is obtained from electron momentum densities calculated using modern computational quantum chemistry density functional theory tools. The calculation, in its simplest form, effectively treats the low-energy (thermalised, room-temperature) positron as a plane wave and gives annihilation ?-spectra that are about 40% broader than experiment, although the main chemical trends are reproduced. We show that this effective ‘narrowing’ of the experimental spectra is due to the action of the molecular potential on the positron, chiefly, due to the positron repulsion from the nuclei. It leads to a suppression of the contribution of small positron-nuclear separations where the electron momentum is large. To investigate the effect of the nuclear repulsion, as well as that of short-range electron-positron and positron-molecule correlations, a linear combination of atomic orbital description of the molecular orbitals is employed. It facilitates the incorporation of correction factors which can be calculated from atomic many-body theory and account for the repulsion and correlations. Their inclusion in the calculation gives ?-spectrum linewidths that are in much better agreement with experiment. Furthermore, it is shown that the effective distortion of the electron momentum density, when it is observed through positron annihilation ?-spectra, can be approximated by a relatively simple scaling factor.

Green, D. G.; Saha, S.; Wang, F.; Gribakin, G. F.; Surko, C. M.

2012-03-01

153

Determination of gamma radioactivity levels and associated dose rates of soil samples of the Akkuyu/Mersin using high-resolution gamma-ray spectrometry.  

PubMed

In this study several soil samples were collected from the Büyükeceli district where Turkey's first nuclear power plant will be built and radioactivity concentrations of (226)Ra, (232)Th, (40)K and (137)Cs were determined by gamma spectrometry using a high-purity germanium detector. The measured activity concentrations in soil samples ranged from 9.8 ± 0.7 to 258.6 ± 15.8, 11.7 ± 0.9 to 85.6 ± 5.0, 173.8 ± 2.1 to 1949.5 ± 14.7 and 0.4 ± 0.1 to 72.2 ± 2.2 Bq kg(-1) for (226)Ra, (232)Th, (40)K and (137)Cs, respectively. Findings are in good agreement with the published results of neighbouring areas. The absorbed gamma dose rate (D) in air and the annual effective dose of soil samples were calculated to be 80.2 nGy h(-1) and 98.3 mSv y(-1), respectively. The results show that the radiation hazard in the Büyükeceli district is insignificant. The data presented in this study would be very useful to determine the future effects of the nuclear power plant to the environment. PMID:24214909

Ozmen, S F; Boztosun, I; Yavuz, M; Tunç, M R

2014-03-01

154

The VHE gamma-ray spectra of several hard-spectrum blazars from long-term observations with the VERITAS telescope array  

NASA Astrophysics Data System (ADS)

Analysis is presented on VERITAS observations of the very high energy gamma-ray spectra of five high frequency peaked BL Lac objects over a range of redshifts. Each object has an unusually hard intrinsic GeV spectrum, and is expected to produce TeV gamma-ray emission into the optically- thick regime of the universe's diffuse extragalactic background light (EBL). Hard spectrum HBLs have recently emerged as an effective tool for measurement of the EBL spectrum, due to extinction of gamma-ray signals from blazars via the pair production interaction gamma-TeVgamma EBL ? e+e -. The VERITAS collaboration has approved long term observations on several of these sources, with the specific intent of studying their spectra to probe for absorption features resulting from these interactions. An introduction to the field of particle astrophysics is presented, followed by an overview of the EBL and its relation to the evolution of the universe. The VERITAS gamma-ray telescope is described in detail, followed by a full overview of the analysis techniques used to derive gamma-ray spectra from VERITAS data. The analyses of the blazars themselves are presented, followed by a discussion of their application to further constraints of the EBL. Each blazar is de-absorbed with an assumed EBL spectrum. In each case the intrinsic TeV spectrum is consistent with lower-energy gamma-ray emission in the optically-thin regime of the EBL.

Madhavan, Arun

155

Cosmic Infrared Background From Population III Stars and Its Effect on Spectra of High-z Gamma-Ray Bursts  

NASA Technical Reports Server (NTRS)

We discuss the contribution of Population III stars to the near-IR (NIR) cosmic infrared background (CIB) and its effect on spectra of high-z, high-energy gamma-ray bursts (GRBs) and other sources. It is shown that if Population III is composed of massive stars, the claimed NIR CIB excess will be reproduced if only approx. 4% plus or minus 2% of all baryons went through these stars. Regardless of the precise amount of the NIR CIB due to them, they likely left enough photons to provide a large optical depth for high-energy photons from distant GRBs. Observations of such GRBs are expected following the planned launch of NASA's GLAST mission. Detecting such damping in the spectra of high-z GRBs will then provide important information on the emissions from the Population III epoch, and the location of this cutoff may serve as an indicator of the GRBs' redshifts. We also point out the difficulty of unambiguously detecting the CIB part originating from Population III in spectra of low-z blazars.

Kashlinsky, A.

2005-01-01

156

Alpha-Particle and Gamma-Ray Spectra of the U230 Decay Series  

Microsoft Academic Search

The radiations of the U230 family have been investigated with an electromagnetic alpha-particle spectrograph and gamma-ray scintillation counters. The following alpha groups were found: U230-5.884 (67.2%), 5.813 (32.1%), 5.658 (0.7%); Th226-6.330 (79%), 6.220 (19%), 6.095 (1.7%), 6.029 (0.6%); Ra222-6.551 Em218-7.127 Mev. The following gamma rays were seen: U230-72 (0.75%), 158 (0.33%); 232 (0.24%); Th226-112 (4.8%); 131 (0.4%), 197 (0.40%), 242

Frank Asaro; I. Perlman

1956-01-01

157

A Compton filter to improve photopeak intensity evaluation in gamma ray spectra  

NASA Astrophysics Data System (ADS)

A procedure for filtering the photopeak intensity from the Compton continuum interference is described. A continuum energy region of up to 0.478 and the 0.662 MeV photopeak are well defined in a cesium-137 theoretical spectrum. The filter was applied to a high intensity Compton region in the gamma spectrum obtained by the attenuation measurements in laboratory experiments. A Cs-137 ( ? = 0.662 MeV) source, of 4 m Ci, steel tubes and a NaI detector was utilized for measuring the catalyst density in a collimated gamma beam. Such an assembly simulates the measuring conditions for gamma tomography in the riser of a FCC-fluid catalyst cracking unit. A Canberra multichannel data acquisition, records the gamma spectrum whose data file is exported to the Matlab software. Following the spectrum reconstruction, the peak area evaluation in both systems, shows a good agreement. Based on the Fourier transform equation, a filtering method for the photopeak, using Matlab functions, was developed. By means of a lowpass filter that lets the low frequencies pass, but not the high frequencies. The filtering results in a significant reduction in the interference from the Compton effect on the photopeak. For little interference and also for a high continuum background under a nonsymmetrical photopeak the filtering works. After the filtering process the peak becomes fairly similar to a Gaussian curve and the liquid counts are enhanced. The associated standard deviation decreases by a factor of 4, while the resolution of the 0.662 MeV photopeak, is kept within detector characteristics.

da Costa, P. C. L.; Dantas, C. C.; Lira, C. A. B. O.; dos Santos, V. A.

2004-11-01

158

A Compton filter to improve photopeak intensity evaluation in gamma ray spectra  

Microsoft Academic Search

A procedure for filtering the photopeak intensity from the Compton continuum interference is described. A continuum energy region of up to 0.478 and the 0.662 MeV photopeak are well defined in a cesium-137 theoretical spectrum. The filter was applied to a high intensity Compton region in the gamma spectrum obtained by the attenuation measurements in laboratory experiments. A Cs-137 (?=0.662

P. C. L. da Costa; C. C. Dantas; C. A. B. O. Lira; V. A. dos Santos

2004-01-01

159

Self-Correction of Lanthanum-Cerium Halide Gamma Spectra (pre-print)  

Microsoft Academic Search

Lanthanum-cerium halide detectors generally exhibit superior energy resolutions for gamma radiation detection compared with conventional sodium iodide detectors. However, they are also subject to self-activities due to lanthanum-138 decay and contamination due to beta decay in the low-energy region and alpha decay in the high-energy region. The detectors self-activity and crystal contamination jointly contribute a significant amount of uncertainties to

Ding Yuan; Paul Guss; Sanjoy Mukhopadhyay

2009-01-01

160

Pair Production Absorption Troughs in Gamma-Ray Burst Spectra: A Potential Distance Discriminator  

Microsoft Academic Search

In order to explain the emergence of a high-energy continuum in gamma-ray bursts detected by EGRET, relativistic bulk motion with large Lorentz factors has recently been inferred for these sources regardless of whether they are of Galactic or cosmological origin. This conclusion results from calculations of internal pair production opacities in bursts that usually assume an infinite power-law source spectrum

Matthew G. Baring; Alice K. Harding

1997-01-01

161

Pair Production Absorption Troughs in Gamma-Ray Burst Spectra: A Potential Distance Discriminator  

Microsoft Academic Search

Relativistic bulk motion with large Lorentz factors has recently been\\u000ainferred for gamma-ray bursts regardless of whether they are of galactic or\\u000acosmological origin. This conclusion results from calculations of internal pair\\u000aproduction transparency in bursts that usually assume an infinite power-law\\u000asource spectrum for simplicity, an approximation that is quite adequate for\\u000asome bursts detected by EGRET. However, for

Matthew G. Baring; Alice K. Harding

1997-01-01

162

Pair Production Absorption Troughs in Gamma-Ray Burst Spectra: A Potential Distance Discriminator  

E-print Network

Relativistic bulk motion with large Lorentz factors has recently been inferred for gamma-ray bursts regardless of whether they are of galactic or cosmological origin. This conclusion results from calculations of internal pair production transparency in bursts that usually assume an infinite power-law source spectrum for simplicity, an approximation that is quite adequate for some bursts detected by EGRET. However, for a given bulk Lorentz factor \\teq{\\Gamma}, photons above the EGRET range can potentially interact with sub-MeV photons in such calculations. Hence it is essential to accurately address the spectral curvature in bursts seen by BATSE. In this paper we present the major properties induced in photon-photon opacity considerations by such spectral curvature. The observed spectral breaks around 1 MeV turn out to be irrelevant to opacity in cosmological bursts, but are crucial to estimates of source transparency in the 1 GeV -- 1 TeV range for sources located in the galactic halo. We find that broad absorption troughs can arise at these energies for suitable bulk motion parameters \\teq{\\Gamma}. Such troughs are probably an unambiguous signature of a galactic halo population, and if observed by experiments such as Whipple, MILAGRO and GLAST, would provide powerful evidence that such bursts are not at cosmological distances.

Matthew G. Baring; Alice K. Harding

1997-04-10

163

Spatially-Dependent Measurements of Surface and Near-Surface Radioactive Material Using In situ Gamma Ray Spectrometry (ISGRS) For Final Status Surveys  

SciTech Connect

In-situ, high-resolution gamma-ray spectrometry (ISGRS) measurements were conducted at the Oak Ridge Institute for Science and Education (ORISE) field laboratory in Oak Ridge, Tennessee. The purpose of these tests was to provide analytical data for assessing how “fit for use” this technology is for detecting discrete particles in soil.

J. A. Chapman, A. J. Boerner, E. W. Abelquist

2006-11-15

164

Spectra of $gamma$-rays from capture of 2 eV to 9 x 10 eV neutrons by ¹¹Ta  

Microsoft Academic Search

Using new experimental techniques, the spectra of $gamma$-rays from the ; capture of neutrons by ¹¹Ta were measured at the Livermore 100-MeV linac ; for neutrons from 2 eV to 9 x 10 eV with a (Ge(Li)-NaI) three-crystal ; spectrometer. Individual primary $gamma$-ray lines were resolved to 1778-keV ; excitation in ¹²Ta. Neutron resonances were resolved to 200-eV neutron ;

Stelts

1976-01-01

165

Effects of Gamma-Ray Damage on Energy Spectra and Polarization of a CdTe Detector With the Schottky Barrier for Imaging Equipment  

Microsoft Academic Search

Effects of gamma-ray radiation damage on energy spectra and polarization of the CdTe radiation detector with the Schottky barrier are demonstrated for application to the gamma-ray imaging equipment in diagnostic nuclear medicine. In particular, the polarization recovery mechanism by momentary bias-off (bias refreshment) is incorporated into the detector system, and the effect of radiation damage on the bias refreshment is

S. Kominami; K. Yokoi; K. Tsuchiya; T. Seino; H. Kitaguchi

2006-01-01

166

Mathematical model of gamma-ray spectrometry borehole logging for quantitative analysis  

USGS Publications Warehouse

A technique for analyzing gamma-ray spectral-logging data has been developed, in which a digital computer is used to calculate the effects of gamma-ray attentuation in a borehole environment. The computer model allows for the calculation of the effects of lithology, porosity, density, and the thickness of a horizontal layer of uniformly distributed radioactive material surrounding a centralized probe in a cylindrical borehole. The computer program also contains parameters for the calculation of the effects of well casing, drilling fluid, probe housing, and losses through the sodium-iodide crystal. Errors associated with the commonly used mathematical assumption of a point detector are eliminated in this model. (USGS)

Schimschal, Ulrich

1981-01-01

167

The Application of High-Resolution Gamma-Ray Spectrometry (HRGS) to Nuclear Safeguards, Nonproliferation, and Arms Control Activities  

SciTech Connect

While well-developed methodologies exist for the employment of high- resolution gamma ray spectrometry (HRGS) in determining the isotopic composition of plutonium samples, the potential capabilities of such measurements in determining the properties of nuclear materials otherwise remain largely unexploited. These measurements contain information sufficiently detailed such that not only can the isotopic composition of uranium and plutonium materials be determined, but the details of the spectrum obtained will depend reproducibly upon other factors including the total mass, density, chemical composition, and geometrical configuration of the material, and for certain materials, the elapsed time since chemical processing. The potential thus exists to obtain a `gamma-ray fingerprint` for typical containers or assemblies of nuclear material which will then serve to identify that class of item in a later confirmatory measurement. These measurements have the additional advantage that, by comparison with active interrogation techniques which usually require the introduction of some extraneous form of radiation or other intrusive activity, they are totally passive, and thus impose only minimal additional safety or regulatory burdens on the operators. In the application of these measurements to the verification of treaty-limited items, where the information acquired may be sensitive in nature, the use of the CIVET (Controlled Intrusiveness Verification Technique) approach, where a computer-based interface is employed to limit access to the information obtained, may be followed.

Kane, Walter R.; Lemley, James R.; Forman, Leon

1997-12-31

168

Application of electrospray ionization product ion spectra for identification with atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry - a case study with seized drugs.  

PubMed

Product ion spectra obtained with liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI/MS/MS) were applied to the identification of seized drug samples from atmospheric pressure matrix-assisted laser desorption/ionization product ion spectra (AP-MALDI-MS/MS spectra). Data acquisition was performed in the information-dependent acquisition (IDA) mode, and the substance identification was based on a spectral library previously created with LC-ESI/MS/MS using protonated molecules as precursor ions. A total of 39 seized drug samples were analyzed with both AP-MALDI and LC-ESI techniques using the same triple-quadrupole instrument (AB Sciex 4000QTRAP). The study shows that ESI-MS/MS spectra can be directly utilized in AP-MALDI-MS/MS measurements as the average fit and purity score percentages with AP-MALDI were 90% and 85%, respectively, being similar to or even better than those obtained with the reference LC/ESI-MS/MS method. This fact enables the possibility to use large ESI spectral libraries, not only to ESI analyses but also to analyses with other ionization techniques which produce protonated molecules as the base peak. The data obtained shows that spectral library search works also for analytical techniques which produce multi-component mass spectra, such as AP-MALDI, unless isobaric compounds are encountered. The spectral library search was successfully applied to rapid identification of confiscated drugs by AP-MALDI-IDA-MS/MS. PMID:22987621

Östman, Pekka; Ketola, Raimo A; Ojanperä, Ilkka

2013-02-01

169

Measurement of Danube sediment radioactivity in Serbia and Montenegro using gamma ray spectrometry  

Microsoft Academic Search

The radionuclide content of 54 sediment samples collected from 18 locations distributed along the Vojvodina part of the Danube was determined by means of low-level, high-resolution gamma-spectroscopy. Beside the members of the natural radioactive chains of 238U, 232Th and the natural 40K, 137Cs content of Chernobyl origin was also detected. The data obtained are compared with those collected during four

I. Bikit; J. Slivka; M. Veskovi?; E. Varga; N. Žiki?-Todorovi?; D. Mr?a; S. Forkapi?

2006-01-01

170

Study of medical isotope production facility stack emissions and noble gas isotopic signature using automatic gamma-spectra analysis platform  

NASA Astrophysics Data System (ADS)

The nuclear industry emissions of the four CTBT (Comprehensive Nuclear-Test-Ban Treaty) relevant radioxenon isotopes are unavoidably detected by the IMS along with possible treaty violations. Another civil source of radioxenon emissions which contributes to the global background is radiopharmaceutical production companies. To better understand the source terms of these background emissions, a joint project between HC, ANSTO, PNNL and CRL was formed to install real-time detection systems to support 135Xe, 133Xe, 131mXe and 133mXe measurements at the ANSTO and CRL 99Mo production facility stacks as well as the CANDU (CANada Deuterium Uranium) primary coolant monitoring system at CRL. At each site, high resolution gamma spectra were collected every 15 minutes using a HPGe detector to continuously monitor a bypass feed from the stack or CANDU primary coolant system as it passed through a sampling cell. HC also conducted atmospheric monitoring for radioxenon at approximately 200 km distant from CRL. A program was written to transfer each spectrum into a text file format suitable for the automatic gamma-spectra analysis platform and then email the file to a server. Once the email was received by the server, it was automatically analysed with the gamma-spectrum software UniSampo/Shaman to perform radionuclide identification and activity calculation for a large number of gamma-spectra in a short period of time (less than 10 seconds per spectrum). The results of nuclide activity together with other spectrum parameters were saved into the Linssi database. This database contains a large amount of radionuclide information which is a valuable resource for the analysis of radionuclide distribution within the noble gas fission product emissions. The results could be useful to identify the specific mechanisms of the activity release. The isotopic signatures of the various radioxenon species can be determined as a function of release time. Comparison of 133mXe and 133Xe activity ratios showed distinct differences between the closed CANDU primary coolant system and radiopharmaceutical production releases. According to the concept proposed by Kalinowski and Pistner (2006), the relationship between different isotopic activity ratios based on three or four radioxenon isotopes was plotted in a log-log diagram for source characterisation (civil vs. nuclear test). The multiple isotopic activity ratios were distributed in three distinct areas: HC atmospheric monitoring ratios extended to far left; the CANDU primary coolant system ratios lay in the middle; and 99Mo stack monitoring ratios for ANSTO and CRL were located on the right. The closed CANDU primary coolant has the lowest logarithmic mean ratio that represents the nuclear power reactor operation. The HC atmospheric monitoring exhibited a broad range of ratios spreading over several orders of magnitude. In contrast, the ANSTO and CRL stack emissions showed the smallest range of ratios but the results indicate at least two processes involved in the 99Mo productions. Overall, most measurements were found to be shifted towards the reactor domain. The hypothesis is that this is due to an accumulation of the isotope 131mXe in the stack or atmospheric background as it has the longest half-life and extra 131mXe emissions from the decay of 131I. The contribution of older 131mXe to a fresh release shifts the ratio of 133mXe/131mXe to the left. It was also very interesting to note that there were some situations where isotopic ratios from 99Mo production emissions fell within the nuclear test domain. This is due to operational variability, such as shorter target irradiation times. Martin B. Kalinowski and Christoph Pistner, (2006), Isotopic signature of atmospheric xenon released from light water reactors, Journal of Environmental Radioactivity, 88, 215-235.

Zhang, Weihua; Hoffmann, Emmy; Ungar, Kurt; Dolinar, George; Miley, Harry; Mekarski, Pawel; Schrom, Brian; Hoffman, Ian; Lawrie, Ryan; Loosz, Tom

2013-04-01

171

Natural radioactivity and radiological hazard assessment of soil using gamma-ray spectrometry.  

PubMed

Natural radioactivity in soil samples collected from different places of Bulandshahr, Hapur and Meerut city of Uttar Pradesh, India, using a low-level counting multichannel gamma-ray spectrometer system comprising an NaI(Tl) crystal. The range of (238)U, (232)Th and (40)K activity concentrations varied from 29.6 to 69.2, from 34.9 to 93.8 and from 438.2 to 719.9 , respectively. The activity concentrations of (232)Th are higher than those of (238)U in all the samples. The absorbed dose rate ranges from 53.18 to 110.95 . The values of the annual effective dose indoors are found to vary from 0.26 to 0.54 , whereas outdoors are found to vary from 0.07 to 0.14 . The annual effective dose is marginally below the international recommended value of 1 for the general public. The external and internal hazard indexes of the soil samples are below the recommended limits. The values of the gamma index in soil samples varied from 0.41 to 0.88. The values of the alpha index varied from 0.15 to 0.35. All these values of and are <1.0. It is observed from the results that there is no significant radiation hazard due to natural radionuclides of the soil samples in the studied areas. PMID:23427204

Zubair, Mohd; Verma, Deepak; Azam, Ameer; Roy, Sukanta

2013-08-01

172

Rapid non-destructive quantitative estimation of urania/thoria in mixed thorium uranium di-oxide pellets by high-resolution gamma-ray spectrometry.  

PubMed

A non-destructive technique using high-resolution gamma-ray spectrometry has been standardised for quantitative estimation of uranium/thorium in mixed (ThO2-UO2) fuel pellets of varying composition. Four gamma energies were selected; two each from the uranium and thorium series and the time of counting has been optimised. This technique can be used for rapid estimation of U/Th percentage in a large number of mixed fuel pellets from a production campaign. PMID:11300408

Shriwastwa, B B; Kumar, A; Raghunath, B; Nair, M R; Abani, M C; Ramachandran, R; Majumdar, S; Ghosh, J K

2001-06-01

173

Quantification of gamma-aminobutyric acid in Sri Lankan tea by means of ultra performance tandem mass spectrometry.  

PubMed

Gamma-Aminobutyric acid (GABA), an important bioactive component of tea, acts as a major inhibitory neurotransmitter and is considered to influence other physiological processes in human as well as in planta. In the hereby presented study, the content of this valuable metabolite was investigated in two novel types of Ceylon Tea, explicitly "Silver Tips" and "White Tea", originating from minimally processed buds of the unique cultivar, "TRI 2043". The samples were subjected to hot water infusion, equivalent to the traditional beverage preparation procedure, and analyzed by means of hydrophilic interaction ultra performance liquid chromatography coupled to tandem mass spectrometry (HILIC LC-MS/MS). The registered GABA levels were compared with those obtained for the classic "Black Tea" and "Green Tea" samples from Sri Lanka. A high variation of GABA content was observed among the different tea types, especially in the case of "Silver Tips" and "White Tea", indicating the crucial influence of the manufacturing procedure (processing extent) on the final abundance of the bioactive component of interest. Furthermore, "White Tea" samples boasted the highest GABA concentration reported for this type of tea so far, reaching up to 50% of that characteristic of the high-priced "GABA Tea". Therefore, "White Tea" and "Silver Tips" were proved to be high quality tea with amounts of gamma-aminobutyric acid comparable with those described for similar types before. To our knowledge, this is the first report on HILIC LC-MS/MS application for the quantification of GABA and for in-depth characterization of teas from Sri Lanka. PMID:24868875

Carvalho, Elisabete; Punyasiri, P A Nimal; Somasiri, H P P Sudarshana; Abeysinghe, I Sarath B; Martens, Stefan

2014-04-01

174

Detection of frozen salt in pipes using gamma-ray spectrometry of potassium self-activity  

SciTech Connect

Solar plants that use molten salts as heat transfer fluid need careful control to avoid the freezing of the salt in the pipes; if such a problem occurs, a diagnostic instrument to localize where is the frozen salt plug and to determine its length is useful. If the salt contains potassium (as is the case of the most common mixture used in solar plants, NaNO{sub 3}/KNO{sub 3} 60/40% by weight), the gamma decay of the natural unstable isotope {sup 40}K can be exploited to detect the frozen salt in a non-invasive way. Simulations and experimental results regarding the detectability of such plugs with different masses/lengths are presented. (author)

Grena, Roberto; Scafe, Raffaele; Pisacane, Fabrizio; Pilato, Renzo; Crescenzi, Tommaso; Mazzei, Domenico [ENEA, Casaccia Research Centre, via Anguillarese 301, 00123 S. Maria di Galeria, Rome (Italy)

2010-01-15

175

Determination of Copper by Neutron Activation Analysis in Conjunction with Compton Suppression Gamma Spectrometry  

SciTech Connect

Copper is considered to be an essential element. Its accurate determination in tissues, foods, and other biological materials is needed to study the effect of copper on human nutrition and health. Using and Advance Prediction Computer Program, it has been shown that short-lived {sup 66}Cu (half-life = 5.09 min) can be used to determine copper in biological materials by instrumental neutron activation analysis (INAA). However, it is seldom done in practice-in particular, for low copper content in high-salt biological materials-because of the Compton background interference from nuclides such as {sup 28}Al, {sup 38}Cl, and {sup 24}Na. To eliminate the Compton interference, a preconcentration NAA method has recently been developed in our laboratory using reversed-phase extraction chromatography of copper followed by short irradiation and conventional gamma-spectrometric counting of {sup 66}Cu; the detection limit is {approx}5 ppb.

W. H. Zhang; A. Chatt

2000-06-04

176

Survey of the {sup 137}Cs contamination in Belgium by in-situ gamma spectrometry, a decade after the Chernobyl accident  

SciTech Connect

The residual radiocesium concentration, nearly 10 y after the Chernobyl accident, is measured at different sites on the Belgian territory by means of in-situ gamma-spectrometry. A possible link between the rainfall at the beginning of May 1986 and the actual cesium concentration is investigated. The radiological impact of this contamination, even in the most affected regions in the Ardennes, is very small (<6 {mu}Sv y{sup -1}). 6 refs., 4 figs., 1 tab.

Uyttenhove, J. [Univ. of Gent (Belgium); Pomme, S.; Hardenman, F. [Belgian Nuclear Research Centre, Boeretang (Belgium); Culot, J.P. [A.V. Nuclear, Brussels (Belgium)] [and others

1997-10-01

177

Development and application of Marinelli beaker standards for monitoring radioactivity in Dairy-Products by gamma-ray spectrometry.  

PubMed

Marinelli (reentrant) beakers are recommended for measurement of low-activity radioactive environmental samples, in both liquid and solid phase. The preparation of Marinelli beaker standards of milk powder containing 232ThO2 at secular equilibrium with its daughter radionuclides was studied. Standards were prepared by mixing of known amounts of solid ThO2 and milk powder. The densities of the standards were 0.5-0.7 kg dm(-3). Measurements of calibrated Marinelli beaker standards with HPGe detector showed that the energy dependence of the efficiency is similar to that of a point source, i.e. an almost linear dependence of log-efficiency vs. log-energy in the 200-2000 keV range, however the parabolic correlation fits better. The validity of these standards was checked by comparison with certified standard reference material IAEA-152-Milk powder containing radiocesium and radiopotassium. The results obtained were found to be in a good agreement with the published certified data. The limit of detection for the determination of radiocesium by gamma ray spectrometry under the prevailing experimental conditions is 0.03 Bq (i.e. 0.8 pCi), for samples of dairy products having lower densities of 0.7 kg dm(-1). PMID:15388145

Lavi, N; Alfassi, Z B

2004-12-01

178

International Workshop on Gamma Spectrometry Analysis Codes for U and Pu Isotopics: Workshop Results and Next Steps  

SciTech Connect

In November 2008, the Institute of Nuclear Materials Management (INMM) and the European Safeguards Research and Development Association (ESARDA) co-hosted the International Workshop on Gamma Spectrometry Analysis Codes for U and Pu Isotopics at the Oak Ridge National Laboratory (ORNL). This workshop was conducted in response to needs expressed by the international safeguards community to understand better the capabilities and limitations of the codes; to ensure these codes are sustained; and to ensure updates or revisions are performed in a controlled manner. The workshop was attended by approximately 100 participants. The participants included code developers, code suppliers, safeguards specialists, domestic and international inspectors, process operators, regulators, and programme sponsors from various government agencies. The workshop provided a unique opportunity for code developers, commercial distributors and end users to interact in a hands-on laboratory environment to develop solutions for programmatic and technical issues associated with the various codes. The workshop also provided an international forum for discussing development of an internationally accepted standard test method. This paper discusses the organization of the workshop, its goals and objectives and feedback received from the participants. The paper also describes the significance of the working group's contribution to improving codes that are commonly used during inspections to verify that nuclear facilities are compliant with treaty obligations that ensure nuclear fuel cycle facilities are used for peaceful purposes.

McGinnis, Brent R [ORNL; Solodov, Alexander A [ORNL; Shipwash, Jacqueline L [ORNL; Zhernosek, Alena V [ORNL; McKinney, Teressa L [ORNL; Pickett, Chris A [ORNL; Peerani, Paolo [ORNL

2009-01-01

179

In situ gamma-spectrometry several years after deposition of radiocesium. Part I. Approximation of depth distributions by the Lorentz function.  

PubMed

Several years after the deposition of fallout-radiocesium, the maximal activity of this radionuclide will not remain at the soil surface but be found rather in deeper layers. In order to estimate the total radiocesium contamination of a large area and the resulting gamma-dose rate by in-situ spectrometry, it is necessary to approximate the vertical distribution of this radionuclide by an analytical function. Observations at ten undisturbed grassland soils and Bavaria, Germany, show that the resulting depth distributions can be approximated closely by a three-parameter Lorentz function. This function characterises the observed distributions in all three critical sections, i.e. the surface layer, the distribution around the maximal concentration, and the tail at greater depth. It is also shown that the observed total activity per unit area of the soil due to 137Cs agrees very well with the corresponding value obtained from the integrated Lorentz function. The two coefficients of the Lorentz function, which characterise the location (depth) and width of the maximum in the activity distribution, are shown to be correlated. In part II of this study, it will be shown how the parameters of the Lorentz function can also be obtained by in-situ gamma-ray spectrometry. As a result, it is possible to use in-situ gamma-ray spectrometry to obtain the total 137Cs activity per unit area also for sites where the vertical distribution of this radionuclide in the soil is no longer exponential. PMID:9008007

Hillmann, U; Schimmack, W; Jacob, P; Bunzl, K

1996-11-01

180

Portable microcomputer for the analysis of plutonium gamma-ray spectra. Volume I. Data analysis methodology and hardware description  

SciTech Connect

A portable microcomputer has been developed and programmed for the International Atomic Energy Agency (IAEA) to perform in-field analysis of plutonium gamma-ray spectra. The unit includes a 16-bit LSI-11/2 microprocessor, 32-K words of memory, a 20-character display for user prompting, a numeric keyboard for user responses, and a 20-character thermal printer for hard-copy output of results. The unit weights 11 kg and had dimensions of 33.5 x 30.5 x 23.0 cm. This compactness allows the unit to be stored under an airline seat. Only the positions of the 148-keV /sup 241/Pu and 208-keV /sup 237/U peaks are required for spectral analysis that gives plutonium isotopic ratios and weight percent abundances. Volume I of this report provides a detailed description of the data analysis methodology, operation instructions, hardware, and maintenance and troubleshooting. Volume II describes the software and provides software listings.

Ruhter, W.D.

1984-05-01

181

Portable microcomputer for the analysis of plutonium gamma-ray spectra. Volume II. Software description and listings. [IAEAPU  

SciTech Connect

A portable microcomputer has been developed and programmed for the International Atomic Energy Agency (IAEA) to perform in-field analysis of plutonium gamma-ray spectra. The unit includes a 16-bit LSI-11/2 microprocessor, 32-K words of memory, a 20-character display for user prompting, a numeric keyboard for user responses, and a 20-character thermal printer for hard-copy output of results. The unit weights 11 kg and has dimensions of 33.5 x 30.5 x 23.0 cm. This compactness allows the unit to be stored under an airline seat. Only the positions of the 148-keV /sup 241/Pu and 208-keV /sup 237/U peaks are required for spectral analysis that gives plutonium isotopic ratios and weight percent abundances. Volume I of this report provides a detailed description of the data analysis methodology, operation instructions, hardware, and maintenance and troubleshooting. Volume II describes the software and provides software listings.

Ruhter, W.D.

1984-05-01

182

Optical and infrared absorption spectra of 3d transition metal ions-doped sodium borophosphate glasses and effect of gamma irradiation  

NASA Astrophysics Data System (ADS)

Undoped and transition metals (3d TM) doped sodium borophosphate glasses were prepared. UV-visible absorption spectra were measured in the region 200-900 nm before and after gamma irradiation. Experimental optical data indicate that the undoped sodium borophosphate glass reveals before irradiation strong and broad UV absorption and no visible bands could be identified. Such UV absorption is related to the presence of unavoidable trace iron impurities within the raw materials used for preparation of this base borophosphate glass. The TMs-doped glasses show absorption bands within the UV and/or visible regions which are characteristic to each respective TM ion in addition to the UV absorption observed from the host base glass. Infrared absorption spectra of the undoped and TMs-doped glasses reveal complex FTIR consisting of extended characteristic vibrational bands which are specific for phosphate groups as a main constituent but with the sharing of some vibrations due to the borate groups. This criterion was investigated and approved using DAT (deconvolution analysis technique). The effects of different TMs ions on the FTIR spectra are very limited due to the low doping level (0.2%) introduced in the glass composition. Gamma irradiation causes minor effect on the FTIR spectra specifically the decrease of intensities of some bands. Such behavior is related to the change of bond angles and/or bond lengths of some structural building units upon gamma irradiation.

Abdelghany, A. M.; ElBatal, F. H.; Azooz, M. A.; Ouis, M. A.; ElBatal, H. A.

2012-12-01

183

Optical and infrared absorption spectra of 3d transition metal ions-doped sodium borophosphate glasses and effect of gamma irradiation.  

PubMed

Undoped and transition metals (3d TM) doped sodium borophosphate glasses were prepared. UV-visible absorption spectra were measured in the region 200-900nm before and after gamma irradiation. Experimental optical data indicate that the undoped sodium borophosphate glass reveals before irradiation strong and broad UV absorption and no visible bands could be identified. Such UV absorption is related to the presence of unavoidable trace iron impurities within the raw materials used for preparation of this base borophosphate glass. The TMs-doped glasses show absorption bands within the UV and/or visible regions which are characteristic to each respective TM ion in addition to the UV absorption observed from the host base glass. Infrared absorption spectra of the undoped and TMs-doped glasses reveal complex FTIR consisting of extended characteristic vibrational bands which are specific for phosphate groups as a main constituent but with the sharing of some vibrations due to the borate groups. This criterion was investigated and approved using DAT (deconvolution analysis technique). The effects of different TMs ions on the FTIR spectra are very limited due to the low doping level (0.2%) introduced in the glass composition. Gamma irradiation causes minor effect on the FTIR spectra specifically the decrease of intensities of some bands. Such behavior is related to the change of bond angles and/or bond lengths of some structural building units upon gamma irradiation. PMID:22995547

Abdelghany, A M; ElBatal, F H; Azooz, M A; Ouis, M A; ElBatal, H A

2012-12-01

184

Mass spectrometry.  

NASA Technical Reports Server (NTRS)

Review of the current state of mass spectrometry, indicating its unique importance for advanced scientific research. Mass spectrometry applications in computer techniques, gas chromatography, ion cyclotron resonance, molecular fragmentation and ionization, and isotope labeling are covered. Details are given on mass spectrometry applications in bio-organic chemistry and biomedical research. As the subjects of these applications are indicated alkaloids, carbohydrates, lipids, terpenes, quinones, nucleic acid components, peptides, antibiotics, and human and animal metabolisms. Particular attention is given to the mass spectra of organo-inorganic compounds, inorganic mass spectrometry, surface phenomena such as secondary ion and electron emission, and elemental and isotope analysis. Further topics include mass spectrometry in organic geochemistry, applications in geochronology and cosmochemistry, and organic mass spectrometry.

Burlingame, A. L.; Johanson, G. A.

1972-01-01

185

Pile-up reconstruction algorithm for high count rate gamma-ray spectrometry  

NASA Astrophysics Data System (ADS)

In high count rate ?-ray spectrometry, the pile-up phenomenon turns out to be an important problem with respect to energy resolution and detection efficiency. Pile-up effects occur when two events are detected so close in time that instrumentation cannot properly extract information from both of them. Because this kind of data is incorrect and marginally useful, such data had to be rejected in traditional pulse processors. In times of digital pulse processing however, one can reconstruct piled-up pulse amplitudes by special algebraic approaches. In fully digital signal acquisition, the moving window deconvolution (MWD) method is commonly used. This method requires two parameters to be carefully set, namely the flattop time (dictated by the maximum rise time of the signal) and the shaping time, to accomplish the best possible energy resolution. In this way, the maximum energy resolution is accomplished, but a lot of piled-up events are rejected, reducing detection efficiency. We propose a method that restores some of the pile-up events, using a parallel block MWD implementation where the shaping time parameter differs for every MWD block. Careful detection of as many true events as possible, as well as determining their exact occurrence in time (their respective timestamps) is the key in getting the most out of the measured signal. With proper analysis logic we get more experimental information through reduced dead time, at the cost of controlled and selectively worsened energy resolution, on an event-by-event basis, achieving better overall detection efficiency. This method was tested on real experimental data where the detection efficiency of our method is higher, by a factor of 4.4(9), than the efficiency of a standard method with pile-up rejection at 500 kcps count rate.

Petrovi?, T.; Vencelj, M.; Lipoglavšek, M.; Novak, R.; Savran, D.

2013-04-01

186

An analytic function fit to Monte-Carlo X- and gamma-ray spectra from Thomson thick thermal/nonthermal hybrid plasmas  

E-print Network

We suggest a simple fitting formula to represent Comptonized X- and gamma-ray spectra from a hot ($kT_e \\gtrsim 10$ keV), Thomson thick ($\\tau_T \\gtrsim 5$) hybrid thermal/nonthermal plasma in spherical geometry with homogeneous soft-photon injection throughout the Comptonizing region. We have used this formula to fit a large data base of Monte-Carlo generated photon spectra, and provide correlations between the physical parameters of the plasma and the fit parameters of our analytic fit function. These allow us to construct Thomson thick Comptonization spectra without performing computer intensive Monte Carlo simulations of the high-Thomson-depth hybrid-plasma Comptonization problem. Our formulae can easily be used in data analysis packages such as XSPEC, thus rendering rapid $\\chi^2$ fitting of such spectra to real data feasible.

M. Boettcher; R. Saxena; A. W. Crider

2001-02-16

187

Data acquisition ATCA system for neutron and gamma-rays spectrometries  

SciTech Connect

Digital pulse processing (DPP) systems are known to have better performance than analog ones for neutron and/or gamma-ray pulses. DPP can synthesize almost any pulse response shape without the associated signal degradation which happens in a complex analog path. Measuring techniques involving detectors/spectrometers for fusion diagnostics rely on real-time algorithms, implemented in field programmable gate array (FPGA), for pulse height analysis, pulse shape discrimination, and pileup rejection of digitized pulses in real time for reduced data throughput, monitoring, and control. This article describes a data acquisition system for real-time pulse analysis based on ATCA and contains a 6 GFLPOS ix86-based control unit and a number of transient recorder (TR) modules interconnected through PCI Express links. Each TR module features (i) eight channels of 12 bit resolution with accuracy equal or higher than 10 bits, (ii) 200 Msamples/s of sampling rate achieving 400 Msamples/s in an interleaved architecture, (iii) 2 or 4 Gbytes of local memory, and (iv) two field FPGAs able to perform real-time processing algorithms.

Pereira, R.; Fernandes, A. G.; Sousa, J.; Varandas, C. A. F. [Associacao EURATOM/IST Centro de Fusao Nuclear, Instituto Superior Tecnico, 1049-001 Lisbon (Portugal)

2006-10-15

188

UV-visible and infrared absorption spectra of gamma irradiated CuO-doped lithium phosphate, lead phosphate and zinc phosphate glasses: A comparative study  

NASA Astrophysics Data System (ADS)

Undoped and CuO-doped lithium phosphate, lead phosphate and zinc phosphate glasses were prepared. UV-visible and infrared absorption spectra of the prepared samples were measured before and after successive gamma irradiation. Experimental optical spectra of the undoped samples reveal strong UV absorption bands, which are attributed to the presence of trace iron impurities in both the lithium and zinc phosphate glasses while the lead phosphate glass exhibits broad UV bands due to combined absorption of trace iron impurities and divalent lead ions. The CuO-doped glasses reveal an extra broad visible band due to Cu 2+ ions in octahedral coordination. The effects of gamma irradiation have been analyzed for both the sharing of all constituent components including trace iron impurities. Infrared absorption spectra of the prepared samples were investigated by the KBr disk technique. The FTIR spectra reveal main characteristic absorption bands due to different phosphate groups. The IR spectra are observed to be slightly affected by the increase of CuO in the doping level (0.2-3%) indicating the stability of the main network units.

ElBatal, H. A.; Abdelghany, A. M.; ElBatal, F. H.; ElBadry, Kh. M.; Moustaffa, F. A.

2011-10-01

189

Verification of Monte Carlo Calculations by Means of Neutron and Gamma Fluence Spectra Measurements behind and inside of Iron-Water Configurations  

SciTech Connect

Neutron and gamma spectra were measured behind and inside of modules consisting of variable iron and water slabs that were installed in radial beams of the zero-power training and research reactors AKR of the Technical University Dresden and ZLFR of the University of Applied Sciences Zittau/Goerlitz. The applied NE-213 scintillation spectrometer did allow the measurement of gamma and neutron fluence spectra in the energy regions 0.3-10 MeV for photons and 1.0-20 MeV for neutrons. The paper describes the experiments and presents important results of the measurements. They are compared with the results of Monte Carlo transport calculations made by means of the codes MCNP and TRAMO on an absolute scale of fluences.

Boehmer, Bertram; Konheiser, Joerg; Noack, Klaus; Rogov, Anatoli [FZ Rossendorf, Institut fuer Sicherheitsforschung, PF 510119, D-01314 Dresden (Germany); Grantz, Martin; Mehner, Hans-Christoph [HS Zittau/Goerlitz, FB Maschinenwesen, Theodor-Koerner-Allee 16, D-02763 Zittau (Germany); Hansen, Wolfgang; Stephan, Ingrid [Technische Universitaet Dresden, Institut fuer Energietechnik, D-01062 Dresden (Germany); Hinke, Dietmar; Unholzer, Siegfried [Technische Universitaet Dresden, Institut fuer Kern- und Teilchenphysik, D-01062 Dresden (Germany)

2005-05-24

190

ROLE OF LINE-OF-SIGHT COSMIC-RAY INTERACTIONS IN FORMING THE SPECTRA OF DISTANT BLAZARS IN TeV GAMMA RAYS AND HIGH-ENERGY NEUTRINOS  

SciTech Connect

Active galactic nuclei (AGNs) can produce both gamma rays and cosmic rays. The observed high-energy gamma-ray signals from distant blazars may be dominated by secondary gamma rays produced along the line of sight by the interactions of cosmic-ray protons with background photons. This explains the surprisingly low attenuation observed for distant blazars, because the production of secondary gamma rays occurs, on average, much closer to Earth than the distance to the source. Thus, the observed spectrum in the TeV range does not depend on the intrinsic gamma-ray spectrum, while it depends on the output of the source in cosmic rays. We apply this hypothesis to a number of sources and, in every case, we obtain an excellent fit, strengthening the interpretation of the observed spectra as being due to secondary gamma rays. We explore the ramifications of this interpretation for limits on the extragalactic background light and for the production of cosmic rays in AGNs. We also make predictions for the neutrino signals, which can help probe the acceleration of cosmic rays in AGNs.

Essey, Warren; Kusenko, Alexander [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States); Kalashev, Oleg [Institute for Nuclear Research, 60th October Anniversary Prospect 7a, Moscow 117312 (Russian Federation); Beacom, John F. [Center for Cosmology and Astro-Particle Physics, Ohio State University, Columbus, OH 43210 (United States)

2011-04-10

191

Role of line-of-sight cosmic ray interactions in forming the spectra of distant blazars in TeV gamma rays and high-energy neutrinos  

E-print Network

Active galactic nuclei (AGN) can produce both gamma rays and cosmic rays. The observed high-energy gamma-ray signals from distant blazars may be dominated by secondary gamma rays produced along the line of sight by the interactions of cosmic-ray protons with background photons. This explains the surprisingly low attenuation observed for distant blazars, because the production of secondary gamma rays occurs, on average, much closer to Earth than the distance to the source. Thus the observed spectrum in the TeV range does not depend on the intrinsic gamma-ray spectrum, while it depends on the output of the source in cosmic rays. We apply this hypothesis to a number of sources and, in every case, we obtain an excellent fit, strengthening the interpretation of the observed spectra as being due to secondary gamma rays. We explore the ramifications of this interpretation for limits on the extragalactic background light and for the production of cosmic rays in AGN. We also make predictions for the neutrino signals, which can help probe acceleration of cosmic rays in AGN.

Warren Essey; Oleg Kalashev; Alexander Kusenko; John F. Beacom

2010-11-29

192

Measurements and calculations of the electron recoil spectra from gamma rays emitted by nitrogen for a 14MeV neutron source  

Microsoft Academic Search

The electron recoil spectra from gamma rays produced by the interaction of 14-MeV neutrons with 0.5, 1.0, 3.0, and 7.0 mean-free-paths (mfps) of nitrogen have been measured with NE-213 scintillators positioned at 26, 30, and 120 deg at distances ranging between 7 and 10 m. Thin wall spherical Dewars filled with liquid nitrogen, with radii dimensions equivalent to the above

L. F. Hansen; T. Komoto; E. F. Plechaty; B. A. Pohl; G. S. Sidhu; C. Wong

1977-01-01

193

Derivation of a Relation for the Steepening of TeV Selected Blazar Gamma-Ray Spectra with Energy and Redshift  

NASA Technical Reports Server (NTRS)

We derive a relation for the steepening of blazar gamma-ray spectra between the multi-GeV Fermi energy range and the TeV energy range observed by atmospheric Cerenkov telescopes. The change in spectral index is produced by two effects: (1) an intrinsic steepening, independent of redshift, owing to the properties of emission and absorption in the source, and (2) a redshift-dependent steepening produced by intergalactic pair production interactions of blazar gamma-rays with low energy photons of the "intergalactic background light" (IBL). Given this relation, with good enough data on the mean gamma-ray SED of TeV Selected BL Lacs, the redshift evolution of the IBL can, in principle, be determined independently of stellar evolution models. We apply our relation to the results of new Fermi observations of TeV selected blazars.

Stecker, F.

2010-01-01

194

MSClust: a tool for unsupervised mass spectra extraction of chromatography-mass spectrometry ion-wise aligned data  

Microsoft Academic Search

Mass peak alignment (ion-wise alignment) has recently become a popular method for unsupervised data analysis in untargeted metabolic profiling. Here we present MSClust—a software tool for analysis GC–MS and LC–MS datasets derived from untargeted profiling. MSClust performs data reduction using unsupervised clustering and extraction of putative metabolite mass spectra from ion-wise chromatographic alignment data. The algorithm is based on the

Y. M. Tikunov; S. Laptenok; R. D. Hall; A. G. Bovy; Vos de C. H

2012-01-01

195

Gamma-rays interactions on optical, FTIR absorption and ESR spectra of 3d transition metals-doped sodium silicophosphate glasses  

NASA Astrophysics Data System (ADS)

Glasses of the basic composition mol% 50%P2O5·30%SiO2·20%Na2O together with samples containing one of 3d transition metal oxides (TiO2 ? CuO) were prepared. Combined optical and FTIR absorption spectra of the prepared glasses were measured before and after gamma irradiation with a dose of 8 Mrad (8 × 104 Gy). Undoped sodium phosphosilicate glass reveals strong UV absorption with a peak at 225 nm but with no visible bands. Such UV absorption is related to the presence of unavoidable trace iron impurities contaminated with the chemicals used for preparation of this glass. 3d-transition metal ions-doped glasses exhibit characteristic absorption bands extended in the UV/Vis regions which are characteristics for the specific TM ions. Gamma irradiation causes broadness of the UV absorption bands in the spectrum of the undoped glass and the resolution of three peaks at about 250, 310 and 340 nm beside the appearance of an induced broad visible band centered at about 450 nm. Glasses doped with 3d TM ions reveal variations in their response towards gamma irradiation. FTIR absorption spectra show extended broad vibrational bands which are related to the presence of both vibrational modes due to silicate and phosphate groups but the later groups are predominant due to the high percent of P2O5 (50%). The presence of TM ions within the dopant level (0.2%) causes no obvious changes in the number and position of the IR structural vibrational bands. ESR spectra of 3d TM-ions-doped glasses reveal quite distinct spin resonance after gamma irradiation indicating that unpaired electrons increase through the capturing or releasing of energetic electrons during the irradiation process.

Abdelghany, A. M.; ElBatal, H. A.

2014-06-01

196

Gamma-ray spectrometry method used for radioactive waste drums characterization for final disposal at National Repository for Low and Intermediate Radioactive Waste--Baita, Romania.  

PubMed

The Radioactive Waste Management Department from IFIN-HH, Bucharest, performs the conditioning of the institutional radioactive waste in concrete matrix, in 200 l drums with concrete shield, for final disposal at DNDR - Baita, Bihor county, in an old exhausted uranium mine. This paper presents a gamma-ray spectrometry method for the characterization of the radioactive waste drums' radionuclides content, for final disposal. In order to study the accuracy of the method, a similar concrete matrix with Portland cement in a 200 l drum was used. PMID:24331854

Done, L; Tugulan, L C; Dragolici, F; Alexandru, C

2014-05-01

197

A mass spectrometric analysis of {gamma}-GPS films  

SciTech Connect

{gamma}-glycidoxypropyltrimethoxysilane ({gamma}-GPS) is used for pre-treatment of grit-blasted aluminum before adhesive bonding. This paper discusses analysis of non-reflective grit-blasted surfaces using mass spectrometry of species that were either sputtered off using an ion beam or thermally desorbed as neutrals using a pulsed laser and then post-ionized using a secondary laser. Results show that fragmentation is excessive and structural information is difficult to obtain from the spectra.

Dillingham, R.G.; Boerio, F.J.; Bertelsen, C. [Cincinnati Univ., OH (United States). Dept. of Materials Science and Engineering; Savina, M.R.; Lykke, K.R.; Calaway, W.F. [Argonne National Lab., IL (United States)

1996-06-01

198

Empirical classification of VLT/Giraffe stellar spectra in the wavelength range 6440-6810 A in the gamma Vel cluster, and calibration of spectral indices  

E-print Network

We study spectral diagnostics available from optical spectra with R=17000 obtained with the VLT/Giraffe HR15n setup, using observations from the Gaia-ESO Survey, on the gamma Vel young cluster, in order to determine the fundamental parameters of these stars. We define a set of spectroscopic indices, sampling TiO bands, H-alpha core and wings, and many temperature- and gravity-sensitive lines. Combined indices tau (gamma) are also defined as Teff (log g) indicators over a wide spectral-type range. H-alpha emission-line indices are also chromospheric activity or accretion indicators. A metallicity-sensitive index is also defined. These indices enable us to find a clear difference between gravities of main-sequence and pre-main-sequence stars (as well as giant stars): the (gamma,tau) diagram is thus argued to be a promising distance-independent age measurement tool for young clusters. Our indices were quantitatively calibrated by means of photometry and literature reference spectra (from UVES-POP and ELODIE 3.1 ...

Damiani, F; Micela, G; Randich, S; Gilmore, G; Drew, J E; Jeffries, R D; Frémat, Y; Alfaro, E J; Bensby, T; Bragaglia, A; Flaccomio, E; Lanzafame, A C; Pancino, E; Recio-Blanco, A; Sacco, G G; Smiljanic, R; Jackson, R J; de Laverny, P; Morbidelli, L; Worley, C C; Hourihane, A; Costado, M T; Jofré, P; Lind, K; Maiorca, E

2014-01-01

199

Measurement of cross sections for the ²⁷Al(n,n'. gamma. )²⁷Al reaction near threshold. [Gamma spectra cross section ratios  

Microsoft Academic Search

Cross-section ratios for production of 0.843-, 1.013-, and 2.209-MeV gamma rays at 55° by the ²⁷Al(n,n'..gamma..)²⁷Al reaction relative to fast-neutron fission of ²³⁵U have been measured at intervals of approx. 0.05 MeV from threshold up to approx. 2.5 MeV, with an average neutron energy resolution of approx. 0.08 MeV. These ratios and ENDF\\/B-IV fission cross sections were used to compute

1979-01-01

200

Gamma  

NSDL National Science Digital Library

The Geometric Algorithms for Modeling, Motion, and Animation (GAMMA) research group is part of the Department of Computer Science at the University of North Carolina. Some of the topics of research include haptics, "robot motion planning," collision detection, and "real-time interaction with virtual environments." There are several projects that are described in detail for each of the main areas of investigation. Many recent papers are offered that describe the progress and findings of the group's research. Additionally, there is a large collection of videos demonstrating computer animation, simulation, and interactive applications. Some software can also be downloaded for the GAMMA Web site; however, access to a few of the titles must first be approved by the system administrator.

2007-07-28

201

Characterization by combined optical and FT infrared spectra of 3d-transition metal ions doped-bismuth silicate glasses and effects of gamma irradiation.  

PubMed

Optical and infrared absorption spectral measurements were carried out for binary bismuth silicate glass and other derived prepared samples with the same composition and containing additional 0.2% of one of 3d transition metal oxides. The same combined spectroscopic properties were also measured after subjecting the prepared glasses to a gamma dose of 8 Mrad. The experimental optical spectra reveal strong UV-near visible absorption bands from the base and extended to all TMs-doped samples and these specific extended and strong UV-near visible absorption bands are related to the contributions of absorption from both trace iron (Fe(3+)) ions present as contaminated impurities within the raw materials and from absorption of main constituent trivalent bismuth (Bi(3+)) ions. The strong UV-near visible absorption bands are observed to suppress any further UV bands from TM ions. The studied glasses show obvious resistant to gamma irradiation and only small changes are observed upon gamma irradiation. This observed shielding behavior is related to the presence of high Bi(3+) ions with heavy mass causing the observed stability of the optical absorption. Infrared absorption spectra of the studied glasses reveal characteristic vibrational bands due to both modes from silicate network and the sharing of Bi-O linkages and the presence of TMs in the doping level (0.2%) causes no distinct changes within the number or position of the vibrational modes. The presence of high Bi2O3 content (70 mol%) appears to cause stability of the structural building units towards gamma irradiation as revealed by FTIR measurements. PMID:24326262

ElBatal, F H; Abdelghany, A M; ElBatal, H A

2014-03-25

202

Gamma Emission Spectra from Neutron Resonances in 234,236,238U Measured Using the Dance Detector at Lansce  

NASA Astrophysics Data System (ADS)

An accurate knowledge of the radiative strength function and level density is needed to calculate of neutron-capture cross sections. An additional constraint on these quantities is provided by measurements of ?-ray emission spectra following capture. We present ?-emission spectra from several neutron resonances in 234,236,238U, measured using the DANCE detector at LANSCE. The measurements are compared to preliminary calculations of the cascade. It is observed that the generalized Lorentzian form of the E1 strength function cannot reproduce the shape of the emission spectra, but a better description is made by adding low-lying M1 Lorentzian strength.

Ullmann, J. L.; Bredeweg, T. A.; Couture, A. J.; Haight, R. C.; Jandel, M.; Kawano, T.; Keksis, A. L.; O'Donnell, J. M.; Rundberg, R. S.; Vieira, D. J.; Wouters, J. M.; Wilhelmy, J. B.; Wu, C. Y.; Becker, J. A.; Chyzh, A.; Baramsai, B.; Mitchell, G. E.; Krticka, M.

2013-03-01

203

Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Identification of Yeasts Is Contingent on Robust Reference Spectra  

PubMed Central

Background Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for yeast identification is limited by the requirement for protein extraction and for robust reference spectra across yeast species in databases. We evaluated its ability to identify a range of yeasts in comparison with phenotypic methods. Methods MALDI-TOF MS was performed on 30 reference and 167 clinical isolates followed by prospective examination of 67 clinical strains in parallel with biochemical testing (total n?=?264). Discordant/unreliable identifications were resolved by sequencing of the internal transcribed spacer region of the rRNA gene cluster. Principal Findings Twenty (67%; 16 species), and 24 (80%) of 30 reference strains were identified to species, (spectral score ?2.0) and genus (score ?1.70)-level, respectively. Of clinical isolates, 140/167 (84%) strains were correctly identified with scores of ?2.0 and 160/167 (96%) with scores of ?1.70; amongst Candida spp. (n?=?148), correct species assignment at scores of ?2.0, and ?1.70 was obtained for 86% and 96% isolates, respectively (vs. 76.4% by biochemical methods). Prospectively, species-level identification was achieved for 79% of isolates, whilst 91% and 94% of strains yielded scores of ?1.90 and ?1.70, respectively (100% isolates identified by biochemical methods). All test scores of 1.70–1.90 provided correct species assignment despite being identified to “genus-level”. MALDI-TOF MS identified uncommon Candida spp., differentiated Candida parapsilosis from C. orthopsilosis and C. metapsilosis and distinguished between C. glabrata, C. nivariensis and C. bracarensis. Yeasts with scores of <1.70 were rare species such as C. nivariensis (3/10 strains) and C. bracarensis (n?=?1) but included 4/12 Cryptococcus neoformans. There were no misidentifications. Four novel species-specific spectra were obtained. Protein extraction was essential for reliable results. Conclusions MALDI-TOF MS enabled rapid, reliable identification of clinically-important yeasts. The addition of spectra to databases and reduction in identification scores required for species-level identification may improve its utility. PMID:22022438

Pinto, Angie; Halliday, Catriona; Zahra, Melissa; van Hal, Sebastian; Olma, Tom; Maszewska, Krystyna; Iredell, Jonathan R.; Meyer, Wieland; Chen, Sharon C.-A.

2011-01-01

204

Systematic Measurements of keV-NEUTRON Capture Cross Sections and Capture Gamma-Ray Spectra of pd Isotopes  

NASA Astrophysics Data System (ADS)

The capture cross sections and capture ?-ray spectra of 104,105Pd were measured in the neutron energy region of 15-100 keV as a part of systematic series of measurements. A neutron time-of-flight method was adopted, using a ns pulsed neutron source via the 7Li(p, n)7Be reaction. The capture ?-rays from the samples were measured with an anti-Compton NaI(Tl) spectrometer. The capture yields were obtained by applying a pulse-height weighting technique to the net capture ?-ray pulse-height spectra. The capture cross sections of 104,105Pd were derived with errors less than 5%, using the standard capture cross sections of 197Au. The capture ?-ray spectra of 104,105Pd were also derived by un-folding the respective observed capture ?-ray pulse-height spectra.

Terada, K.; Igashira, M.; Matsuhashi, T.; Katabuchi, T.; Anh, T. T.

2013-03-01

205

Measurements of keV-NEUTRON Capture Cross Section and Gamma-Ray Spectra of 142Nd  

NASA Astrophysics Data System (ADS)

The neutron capture cross section and capture ?-ray spectra of 142Nd in the neutron energy ranges from 15 to 95 keV, and around 550 keV have been measured by the time-of-flight method. Capture ?-rays were detected with an anti-Compton NaI(Tl) spectrometer, and the pulse-height weighting technique was applied to derive the neutron capture cross section. The capture ?-ray spectra were obtained by unfolding the detector pulse-height spectra with the detector response matrix. The results were compared with previous measurements and cross section data in the evaluated nuclear data libraries, JENDL-4.0 and ENDF/B-VII.0.

Katabuchi, T.; Igashira, M.; Tajika, M.; Nakamura, Y.; Kamada, S.; Terada, K.

2013-03-01

206

Intercomparison of inductively coupled plasma mass spectrometry, quantitative neutron capture radiography, and prompt gamma activation analysis for the determination of boron in biological samples.  

PubMed

Boron determination in blood and tissue samples is a crucial task especially for treatment planning, preclinical research, and clinical application of boron neutron capture therapy (BNCT). Comparison of clinical findings remains difficult due to a variety of analytical methods, protocols, and standard reference materials in use. This paper addresses the comparability of inductively coupled plasma mass spectrometry, quantitative neutron capture radiography, and prompt gamma activation analysis for the determination of boron in biological samples. It was possible to demonstrate that three different methods relying on three different principles of sample preparation and boron detection can be validated against each other and yield consistent results for both blood and tissue samples. The samples were obtained during a clinical study for the application of BNCT for liver malignancies and therefore represent a realistic situation for boron analysis. PMID:22918535

Schütz, C L; Brochhausen, C; Hampel, G; Iffland, D; Kuczewski, B; Otto, G; Schmitz, T; Stieghorst, C; Kratz, J V

2012-10-01

207

Construction and Testing of a Neutron and Gamma Spectrometry System Using Pulse Shape Discrimination with an Organic Scintillator.  

National Technical Information Service (NTIS)

The goal of this thesis was to construct and test a neutron detector to measure the energy spectrum of 1 to 14-MeV neutrons in the presence of gammas. A spectrometer based on the process of pulse shape discrimination (PSD) was constructed, in which the sc...

R. S. Pope

1993-01-01

208

Nondestructive and quantitative characterization of TRU and LLW mixed-waste using active and passive gamma-ray spectrometry and computed tomography  

SciTech Connect

The technology being proposed by LLNL is an Active and Passive Computed Tomography (A P CT) Drum Scanner for contact-handled (CH) wastes. It combines the advantages offered by two well-developed nondestructive assay technologies: gamma-ray spectrometry and computed tomography (CT). Coupled together, these two technologies offer to nondestructively and quantitatively characterize mixed- wastes forms. Gamma-ray spectroscopy uses one or more external radiation detectors to passively and nondestructively measure the energy spectrum emitted from a closed container. From the resulting spectrum one can identify most radioactivities detected, be they transuranic isotopes, mixed-fission products, activation products or environmental radioactivities. Spectral libraries exist at LLNL for all four. Active (A) or transmission CT is a well-developed, nondestructive medical and industrial technique that uses an external-radiation beam to map regions of varying attenuation within a container. Passive (P) or emission CT is a technique mainly developed for medical application, e.g., single-photon emission CT. Nondestructive industrial uses of PCT are under development and just coming into use. This report discuses work on the A P CT Drum Scanner at LLNL.

Camp, D.C.; Martz, H.E.

1991-11-12

209

UV-visible and infrared absorption spectra of Bi2O3 in lithium phosphate glasses and effect of gamma irradiation  

NASA Astrophysics Data System (ADS)

Ultraviolet and visible absorption spectra of prepared undoped lithium phosphate glass and samples of the same nominal composition with additional Bi2O3 contents were measured before and after being subjected to gamma doses of 3 and 6 Mrad. The base undoped lithium phosphate glass exhibits strong charge transfer ultraviolet absorption bands, which are related to unavoidable presence of trace iron impurities within the raw materials for the preparation of this glass. Bi2O3-containing glasses show the extension of UV absorption beside the resolution of visible bands at 400, 450, and 700 nm with the increase of Bi2O3 content due the sharing of absorption of Bi3+ ions. Gamma irradiation of the base glass reveals extended induced bands; the UV bands are related to the conversion of some Fe2+ to Fe3+ through photochemical reactions during the irradiation process. The visible induced bands are related to the formation of positive hole centers from the host phosphate glass. Glasses containing Bi2O3 are observed to show some shielding behavior, which is attributed to the presence of heavy weight and large atomic number of Bi3+ ions. Infrared absorption spectral measurements of the base lithium phosphate glass show characteristic vibrational modes which are related to specific phosphate groups. The addition of Bi2O3 in measurable percent produces additional vibrational bands due to the introduction of Bi-O groups such as BiO3 and BiO6.

Marzouk, M. A.; ElBatal, F. H.

2014-06-01

210

Measurement of the 238U neutron-capture cross section and gamma-emission spectra from 10 eV to 100 keV using the DANCE detector at LANSCE  

SciTech Connect

A careful new measurement of the {sup 238}U(n,{gamma}) cross section from 10 eV to 100 keV has been made using the DANCE detector at LANSCE. DANCE is a 4{pi} calorimetric scintillator array consisting of 160 BaF{sub 2} crystals. Measurements were made on a 48 mg/cm{sup 2} depleted uranium target. The cross sections are in general good agreement with previous measurements. The gamma-ray emission spectra, as a function of gamma multiplicity, were also measured and compared to model calculations.

Ullmann, John L [Los Alamos National Laboratory; Couture, A J [Los Alamos National Laboratory; Keksis, A L [Los Alamos National Laboratory; Vieira, D J [Los Alamos National Laboratory; O' Donnell, J M [Los Alamos National Laboratory; Jandel, M [Los Alamos National Laboratory; Haight, R C [Los Alamos National Laboratory; Rundberg, R S [Los Alamos National Laboratory; Kawano, T [Los Alamos National Laboratory; Chyzh, A [NORTH CAROLINA STATE UNIV; Baramsai, B [NORTH CAROLINA STATE UNIV; Wu, C Y [LLNL; Mitchell, G E [NORTH CAROLINA STATE UNIV; Becker, J A [LLNL; Krticka, M [CHARLES UNIV

2010-01-01

211

Gamma Spectroscopy  

NSDL National Science Digital Library

Students use NaI/PMT gamma detectors to gather spectra of several radioactive sources. The full-enrgy peak, Compton edge, Compton shelf and backscatter peaks are identified. The physics of the detection process is emphasized.

Bistrow, Van

2009-01-05

212

In situ gamma-spectrometry several years after deposition of radiocesium. II. Peak-to-valley method.  

PubMed

A new method is introduced for deriving radiocesium soil contaminations and kerma rates in air from in situ gamma-ray spectrometric measurements. The approach makes use of additional information about gamma-ray attenuation given by the peak-to-valley ratio, which is the ratio of the count rates for primary and forward scattered photons. In situ measurements are evaluated by comparing the experimental data with the results of Monte Carlo simulations of photon transport and detector response. The influence of photons emitted by natural radionuclides on the calculation of the peak-to-valley ratio is carefully analysed. The new method has been applied to several post-Chernobyl measurements and the results agreed well with those of soil sampling. PMID:10052678

Gering, F; Hillmann, U; Jacob, P; Fehrenbacher, G

1998-12-01

213

The use of the bulk properties of gamma-ray burst prompt emission spectra for the study of cosmology  

NASA Astrophysics Data System (ADS)

The study of bulk spectral properties of Gamma-Ray Bursts (GRBs) is important to understanding the physics behind these powerful explosions and may even be an aide in studying cosmology. The prompt emission spectral properties have long been studied by a growing community of researchers, and many theories have been developed since the discovery of GRBs. Even though the exact physics of these phenomena is not completely understood, GRBs have been proposed to give insight on other astrophysical phenomena from dark matter to the expansion of the universe. Obviously, using GRBs to study cosmology requires a large sample size to adequately constrain results and provide confident conjectures. For this reason, BATSE and GBM results are paramount to the study of the prompt emission of GRBs. Using results from both instruments, I study the bulk spectral properties of GRBs and describe analysis techniques that can be used to study cosmology.

Goldstein, Adam

214

Pileup Correction Algorithms for Very-High-Count-Rate Gamma-Ray Spectrometry With NaI(Tl) Detectors  

Microsoft Academic Search

In this paper, we propose algorithms that are suitable for gamma-ray spectrometric systems with Nal(Tl) detector that support pileup correction at extremely high count rates of 4 ?? 106 pulses\\/s. The following two algorithms are presented: 1) an algorithm based on modified phase-only correlation (MPOC) for the detection of the beginning of pulses and maximum likelihood estimation (MLE) for the

Miodrag Bolic; Vujo Drndarevic; Wail Gueaieb

2010-01-01

215

F-GAMMA program: Unification and physical interpretation of the radio spectra variability patterns in Fermi blazars and detection of radio jet emission from NLSY1 galaxies  

NASA Astrophysics Data System (ADS)

The F-GAMMA program aims at understanding the physics at work in AGN via a multi-frequency monitoring approach. A number of roughly 65 Fermi-GST detectable blazars are being monitored monthly since January 2007 at radio wavelengths. The core program relies on the 100-m Effelsberg telescope operating at 8 frequencies between 2.6 and 43 GHz, the 30-m IRAM telescope observing at 86, 145 and 240 GHz and the APEX 12-m telescope at 345 GHz. For the targeted sources the LAT instrument onboard Fermi-GST provides gamma-ray light curves sampled daily. Here we discuss two recent findings: A). On the basis of their variability pattern, the observed quasi-simultaneous broad-band spectra can be classified to merely 5 classes. The variability for the first 4 is clearly dominated by spectral-evolution. Sources of the last class vary self-similarly with almost no apparent shift of the peak frequency. The former classes can be attributed to a two-component principal system made of a quiescent optically thin spectrum and a super-imposed flaring event. The later class must be interpreted in terms of a completely different mechanism. The apparent differences among the classes are explained in terms of a redshift modulus and an intrinsic-source/flare parameters modulus. Numerical simulations have shown that a shock-in-jet model can very well describe the observed behavior. It is concluded therefore that only two mechanisms seem to be producing variability. None of the almost 90 sources used for this study show a switch of class indicating that the variability mechanism is either (a) a finger-print of the source, or (b) remains stable on timescales far longer than the monitoring period of almost 4 years. B). Recently it has been disclosed that Narrow Line Seyfert 1 galaxies show gamma-ray emission. Within the F-GAMMA program radio jet emission has been detected from 3 such sources challenging the belief that jets are associated with elliptical galaxies. The recent findings in this area will be discussed.

Angelakis, E.

2012-01-01

216

Analysis of Mass Spectrometry Data for Protein Identification  

E-print Network

.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.2 Mass Spectrometry Pipeline . . . . . . . . . . . . . . . . . . . 8 2.2.1 Tandem Mass Spectrometry (MS/MS) . . . . . . . . . 9 2.3 From Spectra to Proteins

Mohri, Mehryar

217

Rapid determination of radon daughters and of artificial radionuclides in air by online gamma-ray spectrometry.  

PubMed

For the determination of airborne radionuclide concentrations in real time, a fixed filter device was constructed which fits directly onto a germanium detector with standard nuclear electronics and a multichannel analyzer buffer connected via a data line to a personal computer for remote control and on-line spectrum evaluation. The on-line gamma-ray spectrometer was applied to the study of radon decay product concentrations in ground-level air and to the rapid detection of any contamination of the environmental air by artificial radionuclides. At Munich-Neuherberg, depending on the meterological conditions, the measured air concentrations of 214Pb, the first gamma-ray-emitting member of the 222Rn decay series, varied from about 1 to 50 Bq m-3. For the artificial radionuclides 60Co, 131I and 137Cs the detection limits were determined as a function of the varying natural radon daughter concentrations at sampling and counting times of 1 h or 1 day. For these radionuclides minimum detectable air activity concentrations of 0.3 or 0.001 Bq m-3, respectively, were obtained at low radon daughter levels. At high radon daughter levels the respective detection limits were found to be higher by a factor of only about 2. PMID:8393198

Hötzl, H; Winkler, R

1993-01-01

218

Iron and titanium distribution on the moon from orbital gamma ray spectrometry with implications for crustal evolutionary models  

NASA Technical Reports Server (NTRS)

A set of Fe and Ti maps and regional values are obtained from the Apollo 15 and 16 orbital gamma ray data by energy band analysis. High-Ti basalts predominate the early and late stages of mare volcanism with high-Fe basaltic volcanism in the interim. The first evidence of a high-Ti-KREEP basalt association is found in the Aristarchus region. A N-S asymmetry for Fe and Ti in the east limb and farside highlands complicates the E-W asymmetry for Th but substantiates crustal inhomogeneity. The observed crustal inhomogeneity adds an additional objection to the primitive source model for crustal evolution. The high-Ti-KREEP basalt association and the general trend of decreasing mare basalt Ti with time lend support to the cumulate source model; however, this model cannot account for young, high-Ti maria. The dynamic assimilation model better accounts for chemical variations observed on the moon.

Davis, P. A., Jr.

1980-01-01

219

Iron and titanium distribution on the moon from orbital gamma ray spectrometry with implications for crustal evolutionary models  

NASA Astrophysics Data System (ADS)

A set of Fe and Ti maps and regional values are obtained from the Apollo 15 and 16 orbital gamma ray data by energy band analysis. High-Ti basalts predominate the early and late stages of mare volcanism with high-Fe basaltic volcanism in the interim. The first evidence of a high-Ti-KREEP basalt association is found in the Aristarchus region. A N-S asymmetry for Fe and Ti in the east limb and farside highlands complicates the E-W asymmetry for Th but substantiates crustal inhomogeneity. The observed crustal inhomogeneity adds an additional objection to the primitive source model for crustal evolution. The high-Ti-KREEP basalt association and the general trend of decreasing mare basalt Ti with time lend support to the cumulate source model; however, this model cannot account for young, high-Ti maria. The dynamic assimilation model better accounts for chemical variations observed on the moon.

Davis, P. A.

1980-06-01

220

Determination of total fluorine in five coal reference materials by proton-induced gamma-ray emission spectrometry.  

PubMed

The direct non-destructive proton-induced gamma-ray emission (PIGE) technique with a germanium detector was applied to the determination of total fluorine concentration in five coal reference materials (BCR 40, NIST 1632b, NIST 1635, SARM 20 and USGS CLB-1). Duplicate analyses were made from five randomly selected bottles of each coal. Individual data are presented and some problems (calibration, proton stopping power, effects of sample heating by the proton beam, background estimation) which were encountered during this study are discussed. Sensitivity and reproducibility of the determinations, and homogeneity of the coal samples with respect to fluorine contents by analysis of variance were investigated. The present data are also compared with the few published values for these reference samples, including other PIGE data. The use of synthetic standards and spiked samples in the present study suggested that the PIGE method was more accurate than other techniques. PMID:18966506

Roelandts, I; Robaye, G; Delbrouck-Habaru, J M; Weber, G

1996-03-01

221

Effect of small potassium-rich dykes on regional gamma-spectrometry image of a potassium-poor volcanic complex: A case from the Doupovské hory Volcanic Complex, NW Czech Republic  

NASA Astrophysics Data System (ADS)

Basaltic rocks with low K, U and Th contents dominate the entire Volcanic Complex of the Doupovské hory Mts. Significant potassium anomaly exceeding 1.5 atomic wt.% of potassium over an area of 4 × 8 km and 2 atomic wt.% of potassium over an area of 2 × 6 km was defined by airborne gamma-ray spectrometry above the central part of the Doupovské hory Volcanic Complex. The following detailed field study, supported by field and laboratory gamma-spectrometry measurements and geochemical analyses of rock samples, resulted in discovery of a swarm of potassium-rich trachytic dykes. The existence of such highly-differentiated rocks in the volcanic complex was unknown till present. These dykes are commonly less than 1 m wide, but their potassium content varies between 4 and 8 atomic wt.%. Owing to this high-K composition and relative abundance of dykes, the dyke rocks significantly modify the regional pattern of gamma-spectrometry data. The potassium anomaly cannot be explained by the presence of Flurbühl intrusive body dominated by ijolites and essexites, as all these rocks are poor in K, with potassium typically not exceeding 1.5 wt.%. On the other hand, much more extensive intermediate trachybasaltic lavas with K content varying within the range 1.8-3 wt.% cause only minor or undetectable anomalies.

Zuzana, Skácelová; Vladislav, Rapprich; Bed?ich, Ml?och

2009-10-01

222

Spectra from Space  

NSDL National Science Digital Library

This site from the Exploratorium provides information on telescopes and observatories such as the Hubble Space Telescope that are being used to study spectra from space. Gamma-ray, x-ray, ultraviolet, and infrared spectra are all examined. The purpose and discoveries made by each observatory are included along with related hands-on activities like a liquid crystal IR detector activity.

Felter, Neil

2008-05-13

223

A method for determining the analytical form of a radionuclide depth distribution using multiple gamma spectrometry measurements.  

PubMed

When characterizing environmental radioactivity, whether in the soil or within concrete building structures undergoing remediation or decommissioning, it is highly desirable to know the radionuclide depth distribution. This is typically modeled using continuous analytical expressions, whose forms are believed to best represent the true source distributions. In situ gamma ray spectroscopic measurements are combined with these models to fully describe the source. Currently, the choice of analytical expressions is based upon prior experimental core sampling results at similar locations, any known site history, or radionuclide transport models. This paper presents a method, employing multiple in situ measurements at a single site, for determining the analytical form that best represents the true depth distribution present. The measurements can be made using a variety of geometries, each of which has a different sensitivity variation with source spatial distribution. Using non-linear least squares numerical optimization methods, the results can be fit to a collection of analytical models and the parameters of each model determined. The analytical expression that results in the fit with the lowest residual is selected as the most accurate representation. A cursory examination is made of the effects of measurement errors on the method. PMID:21482447

Dewey, Steven Clifford; Whetstone, Zachary David; Kearfott, Kimberlee Jane

2011-06-01

224

Radionuclides in the ground-level atmosphere in Vilnius, Lithuania, in March 2011, detected by gamma-ray spectrometry.  

PubMed

This study presents the ground-level air monitoring results obtained in Vilnius, the capital of Lithuania, on 14 March-14 April 2011 after the recent earthquake and subsequent Tsunami having a crucial impact on Japanese nuclear reactors at the Fukushima Daiichi Nuclear Power Plant (NPP) on 11 March 2011. To collect representative diurnal aerosol samples a powerful sampling system ensuring the air filtration rate of 5500 m(3) h(-1) was used. The following artificial gamma-ray emitting radionuclides have been determined: (129m)Te, (132)Te (in equilibrium with its daughter (132)I), (131)I, (134)Cs, (136)Cs and (137)Cs. Activity concentration of the globally distributed fission product (137)Cs has increased from a background value of 1.6 ?Bq m(-3) to the value of 0.9 mBq m(-3) at the beginning of April. The activity ratio (134)Cs/(137)Cs was found to be close to 1, with a slightly higher activity of (134)Cs. The maximum aerosol-associated (131)I activity concentration of 3.45 mBq m(-3) was by four orders of magnitude lower than that measured at the same location in April-May 1986 as a consequence of the Chernobyl NPP accident. The estimated gaseous fraction of iodine-131 constituted about 70% of the total (131)I activity. PMID:22541992

Gudelis, A; Druteikien?, R; Lujanien?, G; Maceika, E; Plukis, A; Remeikis, V

2012-07-01

225

Determination of thermal neutron capture gamma yields.  

E-print Network

A method of analysing Ge(Li) thermal neutron capture gamma spectra to obtain total gamma yields has been developed. Tie method determines both the yields from the well resolved gamma peaks in a spectrum as well as the gamma ...

Harper, Thomas Lawrence

1969-01-01

226

Determination of thermal neutron capture gamma yields  

E-print Network

A method of analysing Ge(Li) thermal neutron capture gamma spectra to obtain total gamma yields has been developed. Tie method determines both the yields from the well resolved gamma peaks in a spectrum as well as the gamma ...

Harper, Thomas Lawrence

1969-01-01

227

HOTSPUR: gamma ray emission from spheres pulsed with D-T neutrons. I. Calibration of improved NE213 detector assembly. II. Comparison of TART/SANDYL electron recoil spectra to experiment; preliminary results  

SciTech Connect

The NE213 scintillator detector was modified so that the pulse height would be linear with electron energy over the full range of interest - up to 7.1 MeV. Absolute calibration was done with four different calibrated gamma sources. An average correction factor is obtained which normalizes SANDYL calculations with respect to the calibration experiments. The procedure for calculating neutron-induced gamma-ray output and electron recoil spectra is described, and experimental data from a number of spherical assemblies are given and compared to TART/SANDYL calculations. (LEW)

Goldberg, E.; Hansen, L.F.; Komoto, T.T.; Pohl, B.A.

1986-09-01

228

Measurement of radionuclides and absorbed dose rates in soil samples of Peshawar, Pakistan, using gamma ray spectrometry.  

PubMed

The analysis of gamma-emitting radionuclides in nature, i.e. (226)Ra, (232)Th, (40)K and (137)Cs, has been carried out in soil samples collected from Peshawar University Campus and surrounding areas using a high purity germanium detector coupled with a computer-based high-resolution multichannel analyser. The activity concentrations in soil ranged from 30.20±0.65 to 61.90±0.95, 50.10±0.54 to 102.80±1.04, 373.60±4.56 to 1082±11.38 and 9.50±0.11 to 46.60±0.42 Bq kg(-1) for (226)Ra, (232)Th, (40)K and (137)Cs, with a mean value of 45±7.70, 67±12.50, 878±180 and 19±9.20 Bq kg(-1), respectively. The radium equivalent activity, internal and external hazard indices have mean values of 203.40±29.40 Bq kg(-1), 0.56 and 0.68, respectively. The mean values of outdoor and indoor absorbed dose rates in air and the annual effective dose equivalents were found to be 106.50 and 128 nGy h(-1) and 0.19 and 0.54 mSv y(-1), respectively. In the present study, (40)K was the major radionuclide present in soil samples. The presence of (137)Cs indicates that this area also received some fallout from the nuclear accident of the Chernobyl power plant in 1986. The activity concentrations of radionuclides found in soil samples during the current investigation were nominal. Therefore, they are not associated with any potential source of health hazard to the public. PMID:22397699

Khan, Hasan M; Ismail, Muhammad; Zia, Muhammad Abid; Khan, Khalid

2012-06-01

229

Matched filtering with background suppression for improved quality of base peak chromatograms and mass spectra in liquid chromatography–mass spectrometry  

Microsoft Academic Search

A time domain filter that combines the properties of matched filtering and two-fold differentiation is presented. The filter coefficients are given by the second derivative of a Gaussian model peak, controlled by the setting of two parameters related to the chromatographic system. The fundamental characteristics of the filter were derived, and its applicability demonstrated for real liquid chromatography–mass spectrometry (LC–MS)

Rolf Danielsson; Dan Bylund; Karin E Markides

2002-01-01

230

Open Mass Spectrometry Search Algorithm  

Microsoft Academic Search

Large numbers of MS\\/MS peptide spectra generated in proteomics experiments require efficient, sensitive and specific algorithms for peptide identification. In the Open Mass Spectrometry Search Algorithm [OMSSA], specificity is calculated by a classic probability score using an explicit model for matching experimental spectra to sequences. At default thresholds, OMSSA matches more spectra from a standard protein cocktail than a comparable

Lewis Y. Geer; Sanford P. Markey; Jeffrey A. Kowalak; Lukas Wagner; Ming Xu; Dawn M. Maynard; Xiaoyu Yang; Wenyao Shi; Stephen H. Bryant

2004-01-01

231

Inner valence molecular orbitals and the structure of X-ray O{sub 4,5}(U) emission spectra of uranium in oxides UO{sub 2} and {gamma}-UO{sub 3}  

SciTech Connect

The efficient participation of the relatively low-lying U6p, 6s and Lns atomic orbitals (AOs) of the neighboring ions and ligands (L) in the formation of outer valence and inner valence molecular orbitals (OVMOs and IVMOs, respectively) was first found when interpreting the fine structure of the X-ray photoelectron spectra. However, the first X-ray O{sub 4,5}(U) emission spectra of uranium in oxides, which could prove the formation of IVMO in them, were low-resolution. In this work, the authors obtained, for the first time, high-resolution emission spectra for uranium in dioxide UO{sub 2} and trioxide {gamma}-UO{sub 3} with the aim of interpreting the fine structure using the results of X-ray photoelectron spectroscopy on the IVMOs in these oxides.

Teterin, Yu.A.; Ivanov, K.E. [Kurchatov Institute Russian Research Center, Moscow (Russian Federation); Terekhov, V.A. [Voronezh State Univ. (Russian Federation)

1995-11-01

232

NDA technology for uranium resource evaluation. Progress report, July 1September 30, 1977. [Gamma ray spectra calculations; disequilibrium probe; photoneutron probe  

Microsoft Academic Search

The work is focused on gamma-ray calculations and computer code modifications in support of borehole logging measurements and surface gamma-ray surveys. The Phase II calculations deal with gamma-ray surface and airborne surveys. The ONETRAN direct fluxes agree very well with those of MCNG for both high (2.65 MeV) and low (450 keV) photon energies. However, the sky-shine fluxes of ONETRAN

1978-01-01

233

Formation and reactions of negative ions relevant to chemical ionization mass spectrometry. I. Cl mass spectra of organic compounds produced by F? reactions  

PubMed Central

A systematic study of the negative-ion chemical ionization mass spectra produced by the reaction of F? with a wide variety of organic compounds has been accomplished. A time-of-flight mass spectrometer fitted with a modified high pressure ion source was employed for these experiments. The F? reagent ion was generated from CF3H or NF3, typically at an ion source pressure of 100 ?m. In pure NF3, F? is the major ion formed and constitutes more than 90% of the total ion intensity. While F? is also the major primary ion formed in pure CF3H, it undergoes rapid ion-molecule reactions at elevated source pressures, yielding (HF)nF? (n = 1?3) ions, which makes CF3H less suitable as a chemical ionization reagent gas. Among the organic compounds investigated were carboxylic acids, ketones, aldehydes, esters, alcohols, phenols, halides, nitriles, nitrobenzene, ethers, amines and hydrocarbons. An intense (M ? 1)? ion was observed in the F? chemical ionization mass spectra of carboxylic acids, ketones, aldehydes and phenols. Alcohols yield only (M + F)? ions upon reaction with F?. A weaker (M + F)? ion was also detected in the F? chemical ionization spectra of carboxylic acids, aldehydes, ketones and nitriles. The F? chemical ionization mass spectra of esters, halides, nitriles, nitrobenzene and ethers are characterized primarily by the ions, RCOO?, X?, CN?, NO2?, and OR?, respectively. In addition, esters show a very weak (M ? 1)? ion (except formates). In the F? chemical ionization spectra of some aliphatic alkanes and o-xylene, a very weak (M + F)? ion was observed. Amines and aliphatic alkenes exhibit only insignificant fragment ions under similar conditions, while aromatic hydrocarbons, such as benzene and toluene are not reactive at all with the F? ion. The mechanisms of the various reactions mentioned are discussed, and several experimental complications are noted. In still other studies, the effects of varying several experimental parameters, including source pressure, relative proportions of the reagent and analyte, and other ion source parameters, on the observed chemical ionization mass spectra were also investigated. In a mixture of NF3 and n-butanol, for example, the ratio of the intensities of the ions characteristic of the alcohol to that of the (HF)nF? ion was found to decrease with increasing sample pressure, with increasing NF3 pressure, and with increasing electron energy. No significant effects on the spectra were observed to result from variation of the source repeller field or the source temperature. The addition of argon to the source as a potential moderator did not alter the F? chemical ionization spectrum significantly, but the use of oxygen appears to inhibit formation of the (HF)nF? cluster ion. The advantages of using F? as a chemical ionization reagent are discussed, and comparisons are made with other reagent ions. PMID:7428746

Tiernan, T. O.; Chang, C.; Cheng, C. C.

1980-01-01

234

Chemical-modification rescue assessed by mass spectrometry demonstrates that gamma-thia-lysine yields the same activity as lysine in aldolase.  

PubMed

The role of active site residues in fructose 1,6-bisphosphate aldolase is investigated by chemical-modification rescue. An active-site mutation, K107C, is constructed in a background where the four solvent-accessible cysteine residues are converted to alanine. The resulting mutant, tetK107C, when reacted with bromoethylamine (BrEA), shows a 40-fold increase in activity (to 80% that of wild type). Determination of the sites and their degree of modification using electrospray ionization Fourier transform mass spectrometry (ESI-FTMS) is developed, allowing correlation of activity after chemical modification rescue to the degree of modification. The stoichiometry of the reaction is 2.5 aminoethylations per subunit, as measured by ESI-FTMS. Protein modification with a double-labeled mix (1:1) of natural abundance isotope (d(0)-BrEA) and 2-bromoethyl-1,1,2,2-d4-amine hydrobromide (d(4)-BrEA), followed by dialysis and trypsin digestion, shows aminoethylated peptides as "twin peptides" separated by four mass units in ESI-FTMS analysis. Using this detection procedure under nondenaturing (native) conditions, C107 is aminoethylated, whereas the four buried thiols remain unlabeled. Aminoethylation of other residues is observed, and correlates with those peptides containing histidine, methionine, and/or the amino terminus. Quantification of the aminoethylation reaction is achieved by labeling with nondeuterated d(0)-BrEA under denaturing conditions following double labeling under native conditions. In addition to complete labeling all five thiols, the intensity of the d(0)-BrEA peak for C107 containing peptides increases, and the change in the d(0)/d(4) ratio between native and denaturing conditions shows 82 +/- 4.5% aminoethylation at C107. This correlation of modification with the recovered activity, indicates that gamma-thia-lysine replaces lysine in the catalytic mechanism. Kinetic constants measured for the rescued K107C mutant enzyme with the substrates fructose 1-phosphate and fructose 1,6-bisphosphate are consistent with the role of the positively charged lysine binding to the C6-phosphate. ESI-FTMS, combined with this double-labeling procedure, allows precise identification of sites and measurement of degree of protein modification. PMID:12070312

Hopkins, Christopher E; O'Connor, Peter B; Allen, Karen N; Costello, Catherine E; Tolan, Dean R

2002-07-01

235

Exposure Dose Reconstruction from EPR Spectra of Tooth Enamel Exposed to the Combined Effect of X-rays and Gamma Radiation  

NASA Astrophysics Data System (ADS)

We have used EPR dosimetry on tooth enamel to show that the combined effect of x-rays with effective energy 34 keV and gamma radiation with average energy 1250 keV leads to a significant increase in the reconstructed absorbed dose compared with the applied dose from a gamma source or from an x-ray source or from both sources of electromagnetic radiation. In simulation experiments, we develop an approach to estimating the contribution of diagnostic x-rays to the exposure dose formed in the tooth enamel by the combined effect of x-rays and gamma radiation.

Kirillov, V. A.; Kuchuro, J. I.

2014-09-01

236

Convenient identification of desulfoglucosinolates on the basis of mass spectra obtained during liquid chromatography-diode array-electrospray ionisation mass spectrometry analysis: method verification for sprouts of different Brassicaceae species extracts.  

PubMed

Over the past decade, glucosinolates (GLs) present in different tissues of Brassicaceae and their breakdown products, especially isothiocyanates formed after myrosinase catalyzed hydrolysis, have been regarded as not only environment friendly biopesticides for controlling soilborne pathogens, but most importantly as promising anticarcinogenic compounds. For these reasons, the identification and quantitative determination of the content of individual glucosinolates in plant material is of great interest. Among the different analytical approaches available today for determining GLs in brassica plant samples, HPLC analysis of their desulfo derivatives (DS-GLs) according to ISO 9167-1, 1992, method is the most widely used. However, the notorious lack of commercially available standards limits its usefulness. To overcome these limitations, liquid chromatography-electrospray ionisation-mass spectrometry was investigated as a potential method for the identification of DS-GLs. The characteristic pattern of fragmentation either in positive or negative ionisation was established based on mass spectra of 11 DS-GL standards, then proposed for additional over 30 most common desulfated GLs. The applicability of MS detection of DS-GLs was verified for real plant samples, the extracts of 14 kinds of brassica sprouts. The results indicated that this methodology combines a convenient identification of DS-GLs with the well established analytical procedure preferred by many researchers. Thus, incorporation of MS detection into popular ISO method seems to result in an improved and more reliable approach to GLs determination. PMID:23352826

Kusznierewicz, Barbara; Iori, Renato; Piekarska, Anna; Namie?nik, Jacek; Bartoszek, Agnieszka

2013-02-22

237

Mass Spectra Alignments and their Significance  

E-print Network

Mass Spectra Alignments and their Significance Sebastian B¨ocker1, Hans-Michael Kaltenbach2 1 Research, Universit¨at Bielefeld B¨ocker, Kaltenbach Mass Spectra Alignments CPM 2005 #12;Overview Mass¨ocker, Kaltenbach Mass Spectra Alignments CPM 2005 #12;Overview Mass Spectrometry in Proteomics Protein

Lonardi, Stefano

238

The role of mass spectrometry in medicinal plant research.  

PubMed

In phytochemical and chemotaxonomic research work mass spectrometry plays an outstandingly important role. Using gas chromatography/mass spectrometry (GC/MS) we established the chemotaxa of Tanacetum vulgare L. Chemotypes with essential oils containing 60-90% of artemisia ketone, carveol, dihydrocarvone, myrtenol, umbellulone, terpinen-4-ol, davanone, and Tagetes species containing various essential oils can be clearly distinguished by their spectra; we examined many variations of Tagetes erecta, T. lucida, T. minuta, T. patula and T. tenuifolia. We have identified alpha-beta-pinene-, 1,8-cineol-, linalool-, camphor-, nerol-, geraniol- and gamma-gurjonene as components of Achillea distans L. Injecting the essential oil direct from the oil-secreting organs of T. minuta plants we identified using GC/MS 6-10 and 16% eugenol from the involucral bract and hypsophyll, respectively, as well as beta-ocimene, dihydrotagetone, tagetone, Z- and E-ocimenones. In the course of studies on essential fatty acids Borago officinalis and Lappula squarrosa were selected from 70 species of the family Boraginaceae to obtain seed oil as a source of gamma-linolenic acid, and for the PG synthesis we isolated several grams of gamma-linolenic acid, as well as C18:4, i.e. octadecatetraenic acid, from L. squarrosa on the basis of the mass spectra. From the seed oil of Aquilegia vulgaris C18:3 (5) from the oil of Limnanthes dougloasii C20:1 (5) and from the seed oils of Delphinium consolida and of Tropaeolum species (T. majus, T. minus, T. peregrinum) C20:1 (11) fatty acids were identified on the basis of spectra. PMID:2962668

Héthelyi, E; Tétényi, P; Dabi, E; Dános, B

1987-11-01

239

A system for low-level the cosmogenic 22 Na radionuclide measurement by gamma–gamma coincidence method using BGO detectors  

Microsoft Academic Search

In this study, a gamma–gamma coincidence spectrometry was developed and examined for environmental low-level cosmogenic 22Na monitoring purposes. The spectrometry consists of two bismuth germanate scintillators (BGO) and XIA LLC Digital Gamma Finder\\u000a (DGF)\\/Pixie-4 software and card package. The developed spectrometry was optimized according to the considerations of output\\u000a count rate and gamma peak energy resolution. This spectrometry provides a

Weihua ZhangJing; Jing Yi; Pawel Mekarski; Ian Hoffman; Kurt Ungar; Ari-Pekka Leppänen

2011-01-01

240

Effect of gamma rays absorbed doses and heat treatment on the optical absorption spectra of silver ion-exchanged silicate glass  

NASA Astrophysics Data System (ADS)

Samples of a commercial silicate glass have been subjected to ion exchange at 320 °C in a molten mixture of AgNO3 and NaNO3 with molar ratio of 1:99 and 5:95 for 60 min. The ion exchange process was followed by gamma irradiation in the dose range of 1-250 kGy and heating at the temperature of 550 °C for different time periods ranging from 10 to 582 min. The spectral absorption in UV-Vis range of the Ag-Na ion exchanged glass was measured and used to determine the states of silver prevailing in the glass during the ion exchange, the gamma irradiation and the heat treatment. The gamma irradiation induced holes and electrons in the glass structure leading to the creation of a brown colour, and silver ions trapped electrons to form silver atoms. We observed the first stage of aggregation after irradiation, as well as after heating. The silver atoms diffused and then aggregated to form nanoclusters after heating at 550 °C. A characteristic band at about 430 nm was induced. The surface Plasmon absorption of silver nanoclusters in the glass indicated that the nanoclusters radius grew between 0.9 and 1.43 nm with increasing of annealing time from 10 to 242 min and then saturated. We also found that the size of aggregates depends on the value of gamma radiation absorbed dose. Contrary to what was expected, we found that 20 kGy is the optimal absorbed dose corresponding to the larger size of the aggregates which decreases for absorbed doses above 20 kGy.

Farah, Khaled; Hosni, Faouzi; Mejri, Arbi; Boizot, Bruno; Hamzaoui, Ahmed Hichem; Ben Ouada, Hafedh

2014-03-01

241

Determination of neptunium in plutonium and mixed uranium-plutonium samples by isotope dilution gamma-spectrometry with 243 Am as a spike  

Microsoft Academic Search

A method was developed for isolating neptunium from Pu, U or mixed oxide (MOX) samples and its determination by isotope dilution -spectrometry (IDGS) using239Np (243Am) as a spike. Extraction chromatography with trilaurylamine fixed on a SGX-C18 support was used for the isolation of Np. The decontamination factors for U, Pu, Am and Pa vary between 1000–2000 and 100, respectively. The

F. Sus; J. L. Parus; W. Raab

1996-01-01

242

Using Gamma Spectrometry to Determine U, Th, and K Signatures in Cap Carbonates of the Death Valley Region and Their Relation to Other Carbonates  

Microsoft Academic Search

We collected spectral gamma data (K, U, Th) and measured sections in cap carbonates (Noonday dolomite) and cap-like carbonates (Beck Spring dolomite) of the Death Valley region in order to explore elemental changes in the post-snowball oceans. The Snowball Earth theory of Hoffman et al. (1998) proposes dramatic post-glacial chemical weathering as large concentrations of carbon were removed from the

M. Hannon; J. Lindberg; C. Barrie; T. Johnson; A. Donatelle; J. Goeden; S. Holter; T. Hickson; K. Theissen; M. Lamb

2004-01-01

243

FRAM (Fixed Energy, Response Function Analysis with Multiple Efficiency): A new, versatile gamma-ray spectrometry code for measuring the isotopic composition of plutonium  

SciTech Connect

We describe the characteristics and features and demonstrate the performance of a new code (FRAM) for determining the isotopic composition of plutonium using gamma-ray spectroscopy. This versatile code can measure an extremely wide range of isotopic compositions and is extremely easy to tailor to specialized measurement conditions. Measurement precision, accuracy, and throughput are significantly improved over previous Los Alamos National Laboratory (LANL) codes. 13 refs., 2 figs., 4 tabs.

Sampson, T.E.; Nelson, G.W.; Kelley, T.A.

1990-01-01

244

MSDash: mass spectrometry database and search.  

PubMed

Along with the wide application of mass spectrometry in proteomics, more and more mass spectrometry data are becoming publicly available. Several public mass spectrometry data repositories have been built on the Internet. However, most of these repositories are devoid of effective searching methods. In this paper we describe a new mass spectrometry data library, and a novel method to efficiently index and search in the library for spectra that are similar to a query spectrum. A public online server have been set up and demonstrated outstanding speed and scalability of our methods. Together with the mass spectrometry library, our searching method can improve the protein identification confidence by comparing a spectrum with the ones that are already characterized in the database. The searching method can also be used alone to cluster the similar spectra in a mass spectrometry dataset together, in order to to improve the speed and accuracy of the protein identification or quantification. PMID:19642269

Wu, Zhan; Lajoie, Gilles; Ma, Bin

2008-01-01

245

Plasma Desorption Mass Spectrometry: Coming of Age.  

ERIC Educational Resources Information Center

Discusses the history and development of Plasma Desorption Mass Spectrometry to determine molecular weights and structures of proteins and polymers. Outlines theory, instrumentation, and sample preparation commonly used. Gives several examples of resulting spectra. (ML)

Cotter, Robert J.

1988-01-01

246

Fast and accurate approach to gamma-spectrum modelling: a validation study with a shielded/unshielded voluminous uranium sample.  

PubMed

gamma-Spectrometry is a basic and widely applied method in nuclear security and nuclear safeguards areas. For addressing the growing needs in education and training, in research and development as well as in practical gamma-spectrometry in these areas, Monte Carlo based web-accessible gamma-spectrum modelling tools have been developed for the European Commission's Nucleonica portal at www.nucleonica.net. A recent validation study has demonstrated a good performance of the implemented simulation approach for modelling realistic gamma-spectra from shielded and unshielded point-like sources. In the present work this approach has been further tested with the use of a 0.2kg voluminous 4.46wt% enriched uranium reference material and a portable 10% HPGe detector. The simulations for shielded and unshielded measurement conditions revealed a good agreement with the experimentally acquired gamma-spectra, both for the detection efficiency values and for the overall spectrum shape and intensity in the energy range up to 2.6MeV. PMID:20385501

Berlizov, A N; Mayer, K

2010-09-01

247

Formation of the 0.511.-MeV line in solar flares. [statistical mechanics of line spectra for gamma rays  

NASA Technical Reports Server (NTRS)

The gamma-ray line produced at 0.51-MeV was studied and is shown to be the result of either of free annihilation of positrons with electrons or of the decay of positronium by 2-photon emission. Positron annihilation from the bound state of positronium may also proceed by 3-photon emission, resulting in a continuum with energies up to 0.51-MeV. Accurate calculations of the rates of free annihilation and positronium formation in a solar-flare plasma are presented. Estimates of the positronium-formulation rates by charge exchange and the rates of dissociation and quenching are also considered. The temperature and density dependence of the ratio of 3-photon to 2-photon emission was obtained. It is shown that when the ratio of free electrons to neutral atoms in the plasma is approximately unity or greater, the Doppler width of the 0.51-MeV line is a function of the temperature of the annihilation region. For the small ion densities characteristics of the photosphere, the width is predominantly a function of the density.

Crannell, C. J.; Joyce, G.; Ramaty, R.; Werntz, C.

1976-01-01

248

Improvement in the determination of 238U, 228-234Th, 226-228Ra, 210Pb, and 7Be by gamma spectrometry on evaporated fresh water samples.  

PubMed

For the U-Th series radionuclides investigation in natural freshwater, a simple, fast, and not laboratory intensive method which consists of evaporating the water samples to dryness in the presence of carriers is presented. The small volume of the residue (1-2 cm3) leads to a good efficiency for gamma counting and limits the self-absorption effect for the low energy gamma rays (less than 200 keV). The best efficiency is obtained with a well-type Ge detector. To determine the evaporation yields a river with a common uranium content, the Seine river (France), was selected. By using internal spikes and more conventional techniques of investigation, we demonstrate that the evaporation is quantitative for U, Th, Ra, Pb, and Be. The residue of a 3 L, standard superficial freshwater, evaporated sample was analyzed in a high efficiency, low background Ge detector, which leads to a sufficient precision for most environmental studies. The method has been applied to rain, river, and lake waters to study the impact of disused uranium mine water inputs on the 238U, 228-234Th, 226-228Ra, 210Pb, and 7Be river and lake contents in the U mining area of Limoges (France). PMID:14620828

Cazala, C; Reyss, J L; Decossas, J L; Royer, A

2003-11-01

249

Combinatorial Approaches for Mass Spectra Recalibration  

Microsoft Academic Search

Mass spectrometry has become one of the most popular analysis techniques in Proteomics and Systems Biology. With the creation of larger datasets, the automated recalibration of mass spectra becomes important to ensure that every peak in the sample spectrum is correctly assigned to some peptide and protein. Algorithms for recalibrating mass spectra have to be robust with respect to wrongly

Sebastian Böcker; Veli Mäkinen

2005-01-01

250

Deuterium/hydrogen ratio analysis of thymol, carvacrol, gamma-terpinene and p-cymene in thyme, savory and oregano essential oils by gas chromatography-pyrolysis-isotope ratio mass spectrometry.  

PubMed

Isotope ratio mass spectrometry online coupled with capillary gas chromatography (GC-Py-IRMS) on column INNOWAX is used in the origin specific analysis and the authenticity control of the phenolic essential oils (EOs). Isotopic data delta(2)H(V-SMOW) of thymol and carvacrol in natural essential oils were evidently more depleted than synthetic products (from -49 to 7 per thousand for thymol and -61 per thousand for carvacrol). delta(2)H(V-SMOW) values of p-cymene, gamma-terpinene and thymol in authentic thyme oils (Thymus vulgaris L. and Thymus zygis L.) were found from -300 to -270 per thousand, from -285 to -248 per thousand and from -259 to -234 per thousand, respectively. delta(2)H(V-SMOW) values of carvacrol and p-cymene in authentic oregano oils (Origanum heracleoticum L., Coridothymus capitatus L. and Origanum compactum L.) varied from -223 to -193 per thousand and from -284 to -259 per thousand, respectively. For authentic Satureja montana subsp. montana essential oils, the mean delta(2)H(V-SMOW) value for aromatic compounds were found to be the following: gamma-terpinene -273 per thousand (SD=4.6 per thousand) and p-cymene -283 per thousand (SD=3.0 per thousand), thymol -245 per thousand (SD=1.8 per thousand) and carvacrol -226 per thousand (SD=1.7 per thousand). In addition, p-cymene was previously found as a precursor of the biosynthesis of thymol and carvacrol in thyme oil, thus, we considered p-cymene as an endogenous reference compound (ERC) for D/H ratio analysis. The isotopic fractionation factors alpha(thymol/p-cymene)=1.05 and alpha(carvacrol/p-cymene)=1.08 were obtained and also used to control the authenticity of the phenolic EOs. PMID:16945376

Nhu-Trang, Tran-Thi; Casabianca, Hervé; Grenier-Loustalot, Marie-Florence

2006-11-01

251

Potential of natural gamma-ray spectrometry for mapping and environmental monitoring of black-sand beach deposits on the northern coast of Sinai, Egypt.  

PubMed

The concentrations and distributions of naturally occurring radioactive materials were studied with the aim of detecting and mapping radioactive anomalies as well as monitoring the environment for black-sand beach deposits in Northern Sinai, Egypt. For this purpose, ground gamma-ray spectrometric surveys were conducted using a portable GS-512 spectrometer, with an NaI (Tl) detector, on an area 77.5 km(2) in surface area located between the cities of Rafah and Elareish on the Mediterranean Sea coast. The results revealed that the black-sand beach deposits could be differentiated according to their total-count (TC) radioactivity into five normally distributed interpreted radiometric lithologic (IRL) units denoted by U1, U2, U3, U4 and U5. The computed characteristic TC radiometric statistics of these five IRL units range from 4.67  to 9.96 Ur for their individual arithmetic means. The computed arithmetic means for the three radioelements K, eU and eTh reach 0.46 %, 2.25 and 6.17 ppm, respectively for the whole study area. Monitoring the environmental effects of radioelement concentrations on the study area showed that the mean natural equivalent radiation dose rate from the terrestrial gamma-radiation of the whole area attains 0.33 mSv y(-1). This average value remains on the safe side and within the maximum permissible safe radiation dose (<1.0 mSv y(-1)) without harm to the individual, except at three scattered points reaching more than these values. Some of the local inhabitants in the region sometimes use black sands as a building material. Consequently, they are not recommended for use as building materials, because the inhabitants will, then, receive a relatively high radioactive dose generated mainly by monazite and zircon minerals, two of the main constituents of black sands. PMID:22869819

Aboelkhair, Hatem; Zaaeimah, Mostafa

2013-04-01

252

{\\\\rtf1\\\\ansi\\\\ansicpg1250\\\\deff0\\\\deflang1038\\\\deflangfe1038\\\\deftab708{\\\\fonttbl{\\\\f0\\\\froman\\\\fprq2\\\\fcharset238{\\\\*\\\\fname Times New Roman;}Times New Roman CE;}}\\\\viewkind4\\\\uc1\\\\pard\\\\f0\\\\fs24 Automated analysis of off-line measured gamma-spectra using \\\\scaps UniSampo\\\\scaps0 gamma-ray spectrum analysis software including criterias for alarming systems\\\\par }  

Microsoft Academic Search

Summary  {\\\\rtf1\\\\ansi\\\\ansicpg1250\\\\deff0\\\\deflang1038\\\\deflangfe1038\\\\deftab708{\\\\fonttbl{\\\\f0\\\\froman\\\\fprq2\\\\fcharset238{\\\\*\\\\fname Times New Roman;}Times New Roman CE;}}\\u000a\\\\viewkind4\\\\uc1\\\\pard\\\\lang2057\\\\f0\\\\fs24 In many laboratories the number of measured routine gamma-spectra can be significant and the labour work to review all the data is time consuming and expensive task. In many cases the routine sample does not normally contain radiation above a detectable level, and still the review of the spectra has to be

M. T. Nikkinen

2005-01-01

253

Spatial mapping of soil and radioactivity redistribution at the hillslope scale using in-situ gamma spectrometry, terrestrial laser scanning and RFID tags after the Fukushima nuclear accident fallout.  

NASA Astrophysics Data System (ADS)

In March 2011, the Fukushima Daiichi Nuclear Power Plant disaster, triggered by the Tohoku earthquake and the consequent tsunami, released a large amount of radionuclides in the environment. To provide a rapid assessment of the soil contamination and its potential redistribution, intensive scientific monitoring has been conducted since July 2011 in our study site, located in the Yamakiya district of Kawamata town, in Fukushima prefecture, Japan, about 37 km from the power plant. In this paper, we summarize and analyze a dataset combining multiple innovative methods deployed inside a 5m x 22m bounded hillslope plot. In addition to runoff volumes and sediments radiocesium concentrations, each major rainfall event was followed by in situ gamma spectrometry measurements. In 2012, to trace the complex behavior of sediments inside the plot, about 300 RFID (Radio-Frequency IDentification) tags representing coarse sediments were scattered and their spatial position was periodically checked using a total station. Finally, several high resolutions Digital Elevation Models were acquired with a terrestrial laser scanner to assess the surface structure and changes. The observed processes at the event scale include interrill and rill erosion, as well as local deposition and remobilization phenomenon. Not only do they directly provide information on the erosion spatio-temporal variability and the associated radionuclides transfers, but combined together they can constitute a solid basis to improve and challenge process-based distributed erosion models.

Patin, Jeremy; Onda, Yuichi; Noguchi, Takehiro; Parsons, Anthony

2013-04-01

254

Detection of pulsed, bremsstrahlung-induced, prompt neutron capture gamma-rays with HPGe detector  

SciTech Connect

The Idaho National Engineering Laboratory (INEL) is developing a novel photoneutron-based nondestructive evaluation technique which uses a pulsed, high-energy (up to 8-MeV) electron accelerator and gamma-ray spectrometry. Highly penetrating pulses of bremsstrahlung photons are produced by each pulse of electrons. Interrogating neutrons are generated by the bremsstrahlung photons interacting within a photoneutron source material. The interactions of the neutrons within a target result in the emission of elemental characteristic gamma-rays. Spectrometry is performed by analyzing the photoneutron-induced prompt gamma-rays acquired between accelerator pulses with a unique, high-purity germanium (HPGe) gamma-ray detection system using a modified transistor reset preamplifier. The detection system, the experimental configuration, and the accelerator operation used to characterize the detection system performance are described. Using a 6.5 MeV electron accelerator and a beryllium metal photoneutron source, gamma-ray spectra were successfully acquired for Al, Cu, polyethylene, NaC1, and depleted uranium targets as soon as 30 {mu}s after each bremsstrahlung (or x-ray) flash.

Jones, J.L.

1996-08-01

255

Small Scale Assessment of Spatial and Vertical Redistribution of Fukushima Fallouts Radiocaesium in Contaminated Soil Using in-situ HPGe Gamma Ray Spectrometry  

NASA Astrophysics Data System (ADS)

After Tohoku earthquake on March 11th 2011, the subsequent tsunami and the resulting Fukushima Daiichi Nuclear Power Plant disaster, gamma emitting particles, first release into the atmosphere, were quickly deposited on the soil surface, with potentially harmful level in the surroundings of the nuclear power plant. Thus, the evaluation of soil deposition pattern, depth migration and afterward radionuclides redistribution and export by erosion and hydrological processes is fundamental for contamination assessments and to plan future actions. Our study site is located 37km from Fukushima power plant, inside the evacuated zone. In this study, we used a bounded erosion plot of 22.1m x 5m to assess global export of sediments and 137Cs. This plot, previously cropped with tobacco, is morphologically divided into inter-rill areas separated by rills that formed into former wheel tracks. The bottom of the plot is subject to deposition of sediments. In order to determine and quantify the internal processes responsible of the export of sediment, the depth distribution of 137Cs is estimated using a portable High Purity Germanium (HPGe) detector. Such a portable device, associated to the high radiation levels, allow an acquisition of spatially distributed data within the plot in a reasonable time (1 min/sample). At the same time, depth distribution of 137Cs are measured using the scrapper plate technique, adapted to obtain a fine resolution in the first, highly contaminated, centimeters of soil. Finally, 137Cs depth profiles, associated with in situ and laboratory gamma spectrums acquired with the portable detector, allow for the detector calibration. Although the initial deposit can reasonably be supposed homogeneous at the plot scale, the dataset obtained 3 months later shows high spatial and temporal variability due to erosion processes. Measurements with the portable HPGe detector proved to be useful at this small scale, avoiding the needs of a large number of soil samples, and our results are promising to understand erosion at larger scale where horizontal patterns of deposition and redistribution are usually supposed homogeneous over quite larger areas.

Patin, J.; Onda, Y.; Yoda, H.; Kato, H.

2011-12-01

256

Spatial distribution of gamma radiation levels in surface soils from Jaduguda uranium mineralization zone, Jharkhand, India, using ?-ray spectrometry, and determination of outdoor dose to the population  

PubMed Central

The concentrations of natural radionuclides in surface soil samples around selected villages of Jaduguda were investigated and compared with the radioactivity level in the region. Concentrations of 238U, 232Th, and 40K were determined by a gamma ray spectrometer using the HPGe detector with 50% relative efficiency, and the radiation dose to the local population was estimated. The average estimated activity concentrations of 238U, 232Th, and 40K in the surface soil were 53.8, 44.2 and 464.2 Bq kg?1 respectively. The average absorbed dose rate in the study area was estimated to be 72.5 nGy h-1, where as the annual effective dose to the population was 0.09 mSv y-1. A correlation analysis was made between measured dose rate and individual radionuclides, in order to delineate the contribution of the respective nuclides towards dose rate. The radio-elemental concentrations of uranium, thorium and potassium estimated for the soils, in the study area, indicated the enrichment of uranium series nuclide. The results of the present study were subsequently compared with international and national recommended values. PMID:21170189

Maharana, Mandakini; Krishnan, Narayani; Sengupta, D.

2010-01-01

257

Characterization of gamma-irradiated polyethylene terephthalate by liquid-chromatography mass-spectrometry (LC MS) with atmospheric-pressure chemical ionization (APCI)  

NASA Astrophysics Data System (ADS)

Low-molecular-weight (low-MW) constituents of polyethylene terephthalate (PET), irradiated with 60Co gamma rays at 25 and 50 kGy, were analyzed by HPLC-MS with atmospheric-pressure chemical ionization (APCI). Consistent with earlier results, the concentrations of the major compounds that are present in the non-irradiated PET do not change perceptibly. However, we find a small but significant increase in terephthalic acid ethylester, from less than 1 mg/kg in the non-irradiated control to ca. 2 mg/kg after 50 kGy, which has not been described before. The finding is important because it gives an impression of the sensitivity of the analytical method. Additionally, it shows that even very radiation-resistant polymers can form measurable amounts of low-MW radiolysis products. The potential and limitations of LC-MS for the analysis of radiolysis products and unidentified migrants are briefly discussed in the context of the question: How can we validate our analytical methods for unknown analytes?

Buchalla, Rainer; Begley, Timothy H.

2006-01-01

258

Neutron sources and spectra from cold fusion  

Microsoft Academic Search

Deterministic methods are used to calculate the neutron and photon sources and spectra that would develop if fusion reactions were occurring in cold fusion experimental devices. The results from the calculations give the neutron and gamma spectra resulting from a 2.45-MeV and a 14.1 MeV neutron source. The neutron source strength from certain (gamma,n) and (alpha,n) reactions are also determined.

T. A. Parish; R. T. Perry; W. B. Wilson

1990-01-01

259

Raman Spectrometry.  

ERIC Educational Resources Information Center

Reviews mainly quantitative analytical applications in the field of Raman spectrometry. Includes references to other reviews, new and analytically untested techniques, and novel sampling and instrument designs. Cites 184 references. (CS)

Gardiner, Derek J.

1980-01-01

260

An attempt to use aerial gamma-ray spectrometry results in petrochemical assessments of the volcanic and plutonic associations of Central Anatolia (Turkey)  

NASA Astrophysics Data System (ADS)

Volcanic and magmatic rocks of Central Anatolia are fairly rich in radioelement concentrations. The aerial gamma-ray spectrometric survey data, gathered for the purpose of radioactive mineral exploration were utilized as an additional tool for the petrochemical classification of the volcanic and magmatics rocks and their environments. The survey data on acidic intrusions (e.g. granite, monzonite and syenite) have revealed radioelement concentrations to occur in wide ranges to be 2-6 wt per cent for potassium (K), 3-15 ppm for uranium (U) and 10-52 ppm for thorium (Th). The chain-like high and moderately high potassium, uranium and thorium anomalies on acid intrusives of the entire area show a halo-shaped feature. Locations and lithological compositions of the volcanic rocks namely lavas, tuffs, ignimbrites and basalts, appear to be reasonably effective on their radioelement concentrations. The highest potassium, uranium and thorium concentrations of the volcanic rocks are around 4 wt per cent, 10 ppm and 35 ppm, respectively. Consequently, depending on the location and composition, volcanics show a very wide range of air absorbed dose rate. The lowest rates, which vary between 10 and 120 nGy/hr, were calculated in the ophiolitic group, thick cultivated soil covering areas, particularly at the centre of the aerial survey area, metamorphosed rocks in the north and young basalts mostly in the Kayseri district. Their average radioelement concentrations were found to be very low, that is, 1.2 wt per cent, 2.3 ppm and 10 ppm for K, U and Th, respectively. Because of the accumulation of soluble uranium isotopes, air absorbed rates stemming from radioactivity of these isotopes at the vicinity of the Kozakl? hot spring reach 440 nGy/hr and exceed 150 nGy/hr at the vicinity of the Nev?ehir geothermal field.

Aydin, ?brahim; Aydo?an, M. Selman; Oksum, Erdinç; Koçak, Ali

2006-11-01

261

International Journal of Mass Spectrometry 229 (2003) 5560 High resolution mass spectrometry using a  

E-print Network

their mass spectra with high resolution. The instrument is compared to time-of-flight mass, as well as to ion of the earliest types of mass spectrometers is the time-of-flight mass spectrometer (TOFMS) [1,2]. AlthoughInternational Journal of Mass Spectrometry 229 (2003) 55­60 High resolution mass spectrometry using

Savin, Daniel Wolf

262

Extracting Salient Information from Mass Spectra of Prostate Cancer  

Microsoft Academic Search

This paper presents an application of multilevel wavelet analysis for high dimensional mass spectrometry data. Low frequency (approximation) coefficients, which contain major information contents of the mass spectra data, are extracted. Approximation of the spectra is reconstructed based on orthogonal wavelet approximation coefficients for locating the key m\\/z values of the mass spectra. Genetic algorithm is then used to select

Yihui Liu; Li Bai

2008-01-01

263

Neutron spectrometry in mixed fields: proportional counter spectrometers.  

PubMed

Proton recoil proportional counters have been successfully used in many laboratories worldwide for more than 30 years in order to measure high-resolution neutron energy spectra. The method is well elaborated and understood, nevertheless high expertise is required for its proper application. Table 4.1 summarises typical basic data for proton recoil proportional counters and the requirements for their application. It is noteworthy that any limiting parameter can vary to a certain degree depending on the quality of the detectors used (design, gas purity, response functions, etc) and their response matrices, the data analysis and the unfolding procedures applied with a correct evaluation of the uncertainties involved. It is also important to lend a critical eye to details during measurements (e.g. environmental and electronics problems) as well as in subsequent analysis and unfolding (e.g. oscillations due to unfolding artefacts or inadequacies in detector response matrices). It is recommended that any spectrometry system (procedures for measurement and data evaluation) should be tested and validated in well-known neutron fields e.g. 252Cf standard fission or 241Am-Be. One should, however, expect that, due to different room scatter conditions, deviations from the ISO spectra may occur, especially for low neutron energies. In order to demonstrate the capability of the recoil proton counter technique, two examples of typical neutron spectra are shown in Figures 4.20 and 4.21, both measured in mixed neutron-gamma fields at nuclear research reactors. PMID:14756169

Tagziria, H; Hansen, W

2003-01-01

264

Atomic Spectra  

NSDL National Science Digital Library

This page from Hyperphysics contains images depicting the light emitted by several elements and their respective spectra. The page also provides a description of how the size of a holographic image scales with the wavelength of the light used to observe it.

Nave, Carl R.

2010-03-12

265

Atomic Spectra  

NSDL National Science Digital Library

This well-illustrated page from Hyperphysics contains the light emitted by several elements and their respective spectra as well. The page also provides a description of how the size of a holographic image scales with the wavelength of the light used to observe it.

Nave, Carl R.

2007-12-20

266

Atomic Spectra  

NSDL National Science Digital Library

In this Flash animation the user can view the atomic emission spectra (400-700nm) of eight different elements. A dragable marker allows the user to approximate the wavelength of the various spectral lines. The effect of resolution can be examined in the sodium spectrum in the region 550-600nm.

267

Gamma-ray burst observations  

Microsoft Academic Search

Gamma-ray bursts (GRBs) are the most luminous known objects in the Universe. Their brief, random appearance in the gamma-ray region had made their study difficult since their discovery, over thirty years ago. There is a rich diversity in the duration and morphology of GRB time profiles. The spectra are characterized by a smooth continuum, usually peaking in the range from

Gerald J. Fishman

2000-01-01

268

atomic spectra 1 Atomic Spectra  

E-print Network

. Eisberg and Resnick: Quantum Physics of Atoms, Molecules, Solids, Nuclei and Particles, pp. 95-119, p286 Physics, pp. 88-93 (Rutherford nuclear model), 93-106 (atomic structure and electron spectra) 2. D. W. Preston and E. R. Dietz: The Art of Experimental Physics, pp. 397- 399, resolution of optical instruments

Glashausser, Charles

269

A Grid Service for Pattern Extraction from Mass Spectrometry Data  

Microsoft Academic Search

The paper presents a Grid Service allowing to detect and extract the longest common sub-spectrum among a set of mass spectrometry spectra data. The service is based on a novel pattern extraction algorithm named LCSS (Longest Common Spectra SubString) that adapts a very popular string matching technique based on Suffix Trees to spectra data. The core of the algorithm and

Mario Cannataro; Pierangelo Veltri

2006-01-01

270

EPR study of free radicals in non- and gamma-irradiated nutritive supplements containing anthocyanins concentrate from lyophilized red wine  

NASA Astrophysics Data System (ADS)

Nutritive supplements Enoviton, Enoviton C and Enoviton CE containing standardized anthocyanins from lyophilized red wine, vitamins (some of them) and excipients were investigated by EPR spectrometry before and after gamma-irradiation. Non-irradiated samples exhibit one singlet line with g=2.0039±0.0002, most probably due to free radicals from anthocyanins. After irradiation with 10 kGy gamma-rays, tablets of ?noviton, ?noviton ? and ?noviton ??, all exhibit complex EPR signals centered at a g-value of g=2.0034. The EPR spectrum of irradiated Enoviton is different from that of ?noviton ? or ?noviton ?? due to the overlap of the spectra of microcrystalline cellulose and the background singlet spectrum present in all tablets with the EPR resonance due to irradiated ascorbic acid (in ?noviton ? and ?noviton ??). Gamma-induced free radicals exhibit long time stability—for a six months period the intensity of central peak decrease with 30-40%.

Mladenova, Ralitsa B.; Firzov, Cyril; Yordanov, Nicola D.

2010-09-01

271

Mass spectrometry of aerospace materials  

NASA Technical Reports Server (NTRS)

Mass spectrometry is used for chemical analysis of aerospace materials and contaminants. Years of analytical aerospace experience have resulted in the development of specialized techniques of sampling and analysis which are required in order to optimize results. This work has resulted in the evolution of a hybrid method of indexing mass spectra which include both the largest peaks and the structurally significant peaks in a concise format. With this system, a library of mass spectra of aerospace materials was assembled, including the materials responsible for 80 to 90 percent of the contamination problems at Goddard Space Flight Center during the past several years.

Colony, J. A.

1976-01-01

272

Broadband Analysis of Bioagents by Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Mass spectrometry was first reported to provide analysis of intact metabolite biomarkers from whole cells in 1975.1 Since then advances in ionization techniques have extended our capabilities to polar lipids and, eventually, to proteins.2, 3 Mass spectrometry provides a broadband detection system, which, however, has great specificity. Bioinformatics plays an important role in providing flexible and rapid characterization of species, based on protein and peptide mass spectra collected in the field.

Fenselau, Catherine; Wynne, Colin; Edwards, Nathan

273

Characterization of carbonitrided and oxidized layers on low-carbon steel by conversion electron Moessbauer spectrometry, X-ray diffractometry, and X-ray photoelectron spectrometry  

SciTech Connect

The structures of low-carbon steel oxidized in an aqueous saline bath at 403 K and a fused salt bath at 673 K after carbonitriding were studied using conversion electron Moessbauer spectrometry (CEMS), x-ray diffractometry (XRD), and x-ray photoelectron spectrometry (XPS). Only a doublet peak caused by poor crystallinity of iron oxyhydroxides (FeOOH) or fine particles of iron oxides such as magnetite (Fe{sub 3}O{sub 4}) and maghemite ({gamma}-Fe{sub 2}O{sub 3}) was detected in the CEMS spectra of the surface of the carbonitrided steel oxidized in the aqueous saline bath. Corrosion resistance of the carbonitrided specimens was increased by oxidizing. The oxidized layers produced in the aqueous saline bath were superior to those produced in the fused salt bath as a result of pores in the carbonitrided zone being filled with finer particles of iron oxides and the production of tight, thick oxide layers of amorphous iron oxyhydroxides or fine iron oxides. Deformation of iron nitride ({gamma}{prime}-Fe{sub 4}N) crystals in the carbonitrided zone could not be detected by oxidizing in the aqueous saline bath but were detected in the fused salt bath at 673 K.

Kurosawa, K.; Li, H.L.; Ujihira, Y.; Nomura, K. [Univ. of Tokyo (Japan)

1999-03-01

274

Probing the mechanisms of electron capture dissociation mass spectrometry with nitrated peptides† †Electronic supplementary information (ESI) available: CID MS/MS spectra of N-acetylated peptides; CID experimental data. See DOI: 10.1039/c0cp00623h  

PubMed Central

Previously we have shown that the presence of 3-nitrotyrosine within a peptide sequence severely depletes the peptide backbone fragments typically observed following electron capture dissociation (ECD) mass spectrometry. Instead, ECD of nitrated peptides is characterised by abundant losses of small neutrals (hydroxyl radicals, water and ammonia). Here, we investigate the origin of ammonia loss by comparing the ECD behaviour of lysine- and arginine-containing nitrated peptides, and their N-acetylated counterparts, and nitrated peptides containing no basic amino acid residues. The results reveal that ammonia loss derives from the N-terminus of the peptides, however, the key finding of this work is the insight provided into the hierarchy of various proposed ECD mechanisms: the Utah-Washington mechanism, the electron predator mechanism and the Oslo mechanism. PMID:20830387

Jones, Andrew W.

2010-01-01

275

Gamma ray line shapes from cadmium zinc telluride detectors: An interim report.  

National Technical Information Service (NTIS)

CdZn telluride (CZT) gamma ray detectors, operating at ambient temperatures, are potentially useful for safeguards applications such as assay and isotopic analysis of nuclear materials in the field. To analyze the complex gamma spectra, the gamma line sha...

M. N. Namboodiri, A. D. Lavietes, J. H. McQuaid

1995-01-01

276

SAMPI: Protein Identification with Mass Spectra Alignments  

Microsoft Academic Search

Background: Mass spectrometry based peptide mass fingerprints (PMFs) offer a fast, efficient, and robust method for protein identification. A protein is digested (usually by trypsin) and its mass spectrum is compared to simulated spectra for protein sequences in a database. However, existing tools for analyzing PMFs often suffer from missing or heuristic analysis of the significance of search results and

Hans-michael Kaltenbach; Andreas Wilke; Sebastian Böcker

2007-01-01

277

Mass Spectra Alignments and Their Significance  

Microsoft Academic Search

Mass Spectrometry has become one of the most popular analysis techniques in Genomics and Systems Biology. We investigate a general framework that allows the alignment (or matching) of any two mass spectra. In particular, we examine the alignment of a reference mass spectrum generated in silico from a database, with a measured sample mass spectrum. In this context, we assess

Sebastian Böcker; Hans-michael Kaltenbach

2005-01-01

278

Mass spectra alignments and their significance  

Microsoft Academic Search

Mass Spectrometry has become one of the most popular analysis techniques in Genomics and Systems Biology. We investigate a general framework that allows the alignment (or matching) of any two mass spectra. In particular, we examine the alignment of a reference mass spectrum generated in silico from a database, with a measured sample mass spectrum. In this context, we assess

Sebastian Böcker; Hans-michael Kaltenbach

2007-01-01

279

Gamma Ray Pulsars: Observations  

NASA Technical Reports Server (NTRS)

High-energy gamma rays are a valuable tool for studying particle acceleration and radiation in the magnetospheres of energetic pulsars. The six or more pulsars seen by CGRO/EGRET show that: the light curves usually have double-peak structures (suggesting a broad cone of emission); gamma rays are frequently the dominant component of the radiated power; and all the spectra show evidence of a high-energy turnover. Unless a new pulsed component appears at higher energies, progress in gamma-ray pulsar studies will be greatest in the 1-20 GeV range. Ground-based telescopes whose energy ranges extend downward toward 10 GeV should make important measurements of the spectral cutoffs. The Gamma-ray Large Area Space Telescope (GLAST), now in planning for a launch in 2005, will provide a major advance in sensitivity, energy range, and sky coverage.

Thompson, David J.; White, Nicholas E. (Technical Monitor)

2000-01-01

280

Infrared spectra of U.S. automobile original finishes (post - 1989). VIII: In situ identification of bismuth vanadate using extended range FT-IR spectroscopy, Raman spectroscopy, and X-ray fluorescence spectrometry.  

PubMed

Chrome Yellow (PbCrO4 ·xPbSO4 ) was a common pigment in U.S. automobile OEM finishes for more than three decades, but in the early 1990s its use was discontinued. One of its main replacements was Bismuth Vanadate (BiVO4 ·nBi2 MoO6 , n = 0-2), which was commercially introduced in 1985, as this inorganic pigment also produces a very bright hue and has excellent outdoor durability. This paper describes the in situ identification of Bismuth Vanadate in automotive finishes using FT-IR and dispersive Raman spectroscopy and XRF spectrometry. Some differentiation of commercial formulations of this pigment is possible based on far-infrared absorptions, Raman data, and elemental analysis. The spectral differences arise from the presence or absence of molybdenum, the use of two crystal polymorphs of BiVO4 , and differences in pigment stabilizers. Bismuth Vanadate is usually not used alone, and it is typically found with Isoindoline Yellow, hydrous ferric oxide, rutile, Isoindolinone Yellow 3R, or various combinations of these. PMID:24261821

Suzuki, Edward M

2014-03-01

281

Infrared Spectra of U.S. Automobile Original Finishes (1998-2000). IX. Identification of Bismuth Oxychloride and Silver/White Mica Pearlescent Pigments Using Extended Range FT-IR Spectroscopy, XRF Spectrometry, and SEM/EDS Analysis.  

PubMed

Bismuth oxychloride (BiOCl) was the first viable synthetic pearl pigment developed 50 years ago. It was only used for a limited time period in automotive paint (model years 1998-2000), serving to produce luster for a single Chrysler black metallic color. Identification of this pigment in an unknown automotive paint can thus facilitate determination of the vehicle of origin. Bismuth oxychloride imparts effects similar to those produced by silver/white mica pearlescent pigments, and such a pigment was used together with bismuth oxychloride in at least one original equipment manufacturer (OEM) basecoat. Silver/white micas are now used primarily in white pearl tricoat systems. This article describes the identification of bismuth oxychloride and silver/white mica pearlescent pigments in automotive finishes using FT-IR spectroscopy, X-ray fluorescence (XRF) spectrometry, and SEM/EDS analysis. Data for some cadmium pigments, which were used in automotive paint several decades ago, are also presented as they produce infrared absorptions similar to that of bismuth oxychloride. PMID:24646090

Suzuki, Edward M

2014-09-01

282

Spectra Luminescence of Extraterrestrial Calcium Phosphates in Mexican Chondrites  

Microsoft Academic Search

Merrillite and apatite crystals from four historical Mexican chondrites were studied by Environmental Scanning Electron Microscopy (ESEM), Energy Dispersive Spectrometry (EDS), Back-scattering (BS), Spectra cathodoluminescence (CL), and Micro-Raman Spectroscopy (MRS). CL is a powerful technique for exciting light emission from intrinsic relaxations, impurities, and imperfections in the outer few microns of the surface of minerals. The spectra CL patterns of

Leticia Alba Aldave; Javier García Guinea; Laura Tormo

2011-01-01

283

Tokamak Fusion Test Reactor charge exchange atom spectrometry using a natural diamond detector  

NASA Astrophysics Data System (ADS)

Natural diamond detectors (NDD) developed in Russia were used for fast charge exchange H0 atom spectrometry and flux dynamic measurements during Tokamak Fusion Test Reactor (TFTR) H+ minority ion cyclotron resonance heating (ICRH) experiments in deuterium plasma. For selected NDDs, the high energy resolution (˜2%-3%) and radiation resistance (5×1014n/cm2) and low sensitivity to neutrons and gammas enable spectrometry of fast (0.2-3 MeV) atoms in TFTR radiation conditions. The NDD compact housing (˜2 cm+3) allowed noninterfering insertion into the particle charge exchange flight tube giving both systems similar views which allows comparison of their spectra and fluxes. A small NDD was chosen to limit count rates to 7×105s-1. A spectroscopy amplifier operating with pileup inspection at such rates was developed, enabling measurement of the dependence of fast perpendicular proton energy spectra on ICRH heating power during sawtooth-free and sawtooth-crash times. The results agree with a model developed for sawtooth redistribution of fast particles.

Krasilnikov, A. V.; Medley, S. S.; Gorelenkov, N. N.; Budny, R. V.; Ignatyev, O. V.; Kaschuck, Yu A.; Petrov, M. P.; Roquemore, A. L.

1999-01-01

284

MAGIC-LC\\/FT-IR spectrometry  

Microsoft Academic Search

The development of a new high performance liquid chromatography (HPLC) interface with Fourier transform infrared (FT-IR) spectrometry is currently being studied. This interface removes HPLC solvents prior to infrared detection. The solvent elimination properties of this interface make it possible to obtain spectra from reverse phase chromatography with no interferences from residual solvent.

Raymond M. Robertson; James A. de Haseth; Richard F. Browner

1988-01-01

285

Matej Mayer RBS -Rutherford Backscattering Spectrometry  

E-print Network

118 (1996) 52 #12;© Matej Mayer 2003 4 History Sir Ernest Rutherford (1871 - 1937) · 1911: Rutherford#12;#12;© Matej Mayer 2003 1 RBS - Rutherford Backscattering Spectrometry M. Mayer Max and kinematics · Rutherford cross section and limitations · RBS spectra from thin and thick films · Stopping

Smith, Richard J.

286

Hadamard Transform Time-of-Flight Mass Spectrometry: A High-Speed Detector for  

E-print Network

spectra s-1 Hadamard transform time-of-flight mass spectrometry (HT-TOFMS) is a promising detector for anyHadamard Transform Time-of-Flight Mass Spectrometry: A High-Speed Detector for Capillary of a Hadamard convolution/deconvolution scheme, the name Hadamard transform time-of-flight mass spectrometry (HT

Zare, Richard N.

287

Preliminary results from the first satellite of a high-resolution germanium gamma-ray spectrometer: Description of instrument, some activation lines encountered, and studies of the diffuse spectra  

NASA Technical Reports Server (NTRS)

Gamma radiation from terrestrial and extraterrestrial sources were investigated with a high resolution Ge(Li) spectrometer-cryogen system flown onboard a low altitude, spin stabilized, polar orbiting satellite. A brief description is given of the instrument and preliminary results obtained from earth orbit are discussed. Attempts were made to use angular distributions and geomagnetic latitude spectral variations to determine diffuse background spectrum, detect gamma ray line emissions from solar flares, and search for positron annihilation radiation coming from the direction of the galactic center.

Nakano, G. H.; Imhof, W. L.; Reagan, J. B.; Johnson, R. G.

1973-01-01

288

{gamma} ray astronomy with muons  

SciTech Connect

Although {gamma} ray showers are muon poor, they still produce a number of muons sufficient to make the sources observed by GeV and TeV telescopes observable also in muons. For sources with hard {gamma} ray spectra there is a relative {open_quotes}enhancement{close_quotes} of muons from {gamma} ray primaries as compared to that from nucleon primaries. All shower {gamma} rays above the photoproduction threshold contribute to the number of muons N{sub {mu}}, which is thus proportional to the primary {gamma} ray energy. With {gamma} ray energy 50 times higher than the muon energy and a probability of muon production by the {gamma}{close_quote}s of about 1{percent}, muon detectors can match the detection efficiency of a GeV satellite detector if their effective area is larger by 10{sup 4}. The muons must have enough energy for sufficiently accurate reconstruction of their direction for doing astronomy. These conditions are satisfied by relatively shallow neutrino detectors such as AMANDA and Lake Baikal, and by {gamma} ray detectors such as MILAGRO. TeV muons from {gamma} ray primaries, on the other hand, are rare because they are only produced by higher energy {gamma} rays whose flux is suppressed by the decreasing flux at the source and by absorption on interstellar light. We show that there is a window of opportunity for muon astronomy with the AMANDA, Lake Baikal, and MILAGRO detectors. {copyright} {ital 1997} {ital The American Physical Society}

Halzen, F. [Department of Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States)] [Department of Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States); Stanev, T. [Bartol Research Institute, University of Delaware, Newark, Delaware 19716 (United States)] [Bartol Research Institute, University of Delaware, Newark, Delaware 19716 (United States); Yodh, G.B. [Department of Physics and Astronomy, University of California, Irvine, California 92715 (United States)] [Department of Physics and Astronomy, University of California, Irvine, California 92715 (United States)

1997-04-01

289

Assessment of ftir spectrometry for pesticide screening of aqueous samples  

Microsoft Academic Search

This article assesses the potential of Fourier transform infrared spectrometry (FTIR) to be used in pesticide screening and determination of selected pyrethroid and organochlorine pesticides in fresh water. FTIR spectra of 28 single pesticides in the dry state were recorded on a horizontal diamond attenuated total reflection (ATR) element. Hierachical cluster analysis of the recorded FTIR spectra (spectral range: 4000–500?cm)

Almudena ColumÉ; Josef Diewok; Bernhard Lendl

2004-01-01

290

Antagonistic properties of a natural product – Bicuculline with the gamma-aminobutyric acid receptor: Studied through electrostatic potential mapping, electronic and vibrational spectra using ab initio and density functional theory  

Microsoft Academic Search

(+)-Bicuculline (hereinafter referred to as bicuculline), a phthalide isoquinoline alkaloid is of current interest as an antagonist of gamma-aminobutyric acid (GABA). Its inhibitor properties have been studied through molecular electrostatic potential (MEP) mapping of this molecule and GABA receptor. The hot site on the potential surface of bicuculline, which is also isosteric with GABA receptor, has been used to interpret

Anubha Srivastava; Poonam Tandon; Sudha Jain; B. P. Asthana

2011-01-01

291

(2/94)(9-11/95)(1-4/00) Neuman Chapter 5 Organic Spectrometry  

E-print Network

Hexane Exact Mass Values M+1 Peaks and Isotopes Mass Spectra of Hexane Structural Isomers (5.2D) 5-5 Mass Spectrometry (MS) Nuclear Magnetic Resonance Spectrometry (NMR) Infrared Spectrometry (IR Spectrometry 5-26 The NMR Spectrometer (5.4A) 5-26 1H and 13C are NMR Active Nuclei (5.4B) 5-27 5.5 13C NMR

Reed, Christopher A.

292

Galaxy and Stellar Spectra  

NSDL National Science Digital Library

In this activity students learn that galaxies shine on the basis of their intergrated stellar population, therefore, adding together different stellar spectra should reproduce the spectra of a galaxy. This activity contains an applet which allows one to add spectra of up to four different stars to produce a resultant spectra. To reproduce qualitatively a spectra of a galaxy one can add together and F main sequence star and a K Giant. The spectra are normalized by V-band luminosity.

Department, University O.

2005-06-17

293

Analysis of High-Fold Gamma Data  

SciTech Connect

Historically, {gamma}-{gamma} and {gamma}-{gamma}-{gamma} coincidence spectra were utilized to build nuclear level schemes. With the development of large detector arrays, it has became possible to analyze higher fold coincidence data sets. This paper briefly reports on software to analyze 4-fold coincidence data sets that allows creation of 4-fold histograms (hypercubes) of at least 1024 channels per side (corresponding to a 43 gigachannel data space) that will fit onto a few gigabytes of disk space, and extraction of triple-gated spectra in a few seconds. Future detector arrays may have even higher efficiencies, and detect an many as 15 or 20 {gamma} rays simultaneously; such data will require very different algorithms for storage and analysis. Difficulties inherent in the analysis of such data are discussed, and two possible new solutions are presented, namely adaptive list-mode systems and list-list-mode storage.

Beyer, C.J.; Cromaz, M.; Radford, D.C.

1998-08-10

294

Towards de novo identification of metabolites by analyzing tandem mass spectra  

Microsoft Academic Search

Motivation: Mass spectrometry is among the most widely used technologies in proteomics and metabolomics. Being a high- throughput method, it produces large amounts of data that necessitates an automated analysis of the spectra. Clearly, database search methods for protein analysis can easily be adopted to analyze metabolite mass spectra. But for metabolites, de novo interpretation of spectra is even more

Sebastian Böcker; Florian Rasche

2008-01-01

295

Classification of High-Resolution NMR Spectra Based on Complex Wavelet Domain Feature Selection and Kernel-  

E-print Network

Classification of High-Resolution NMR Spectra Based on Complex Wavelet Domain Feature Selection spectra based on the selected features. Our experiments with real NMR spectra showed that the proposed signal. In [6], decimated discrete wavelet transform was employed to analyze mass spectrometry data

Wang, Zhou

296

Detection of low levels of plutonium in natural environments from gamma-ray spectra with advanced methods in robust fitting 1 This work is supported in part by the Department of Defense Nuclear Treaty Programs Office through the United States Army Space and Missile Defense Command agent for the Defense Advanced Research Projects Agency and performed at the Pinellas Science, Technology, and Research Center under Grant DASG-609-610-007. 1  

Microsoft Academic Search

A newly developed spectral analysis methodology, RobWin, is experimentally tested for its ability to identify plutonium in highly background-dominated gamma-ray spectra. The method, which builds upon nonlinear robust fitting techniques from RobFit spectral analysis software, emphasizes gradually adding structure to the entire spectrum background shape function after accounting for re-optimized combinations of entire-spectrum photopeak response functions from a user-defined set

G. P Lasche; R. L Coldwell; J. A Nobel

1999-01-01

297

Deconvolution of Alpha Spectra From Hot Particles  

Microsoft Academic Search

A computer code known as AASIFIT is developed to unfold complex alpha spectra. Peak shapes used in the fitting are obtained\\u000a from the simulations. In addition to activities of the nuclides present in the sample, the code can provide source characterization.\\u000a AASIFIT is applied for a nuclear bomb particle collected in Thule, Greenland. It is shown that direct alpha spectrometry

Roy Pöllänen; Tero Karhunen; Teemu Siiskonen; Harri Toivonen; Andreas Pelikan

298

Advanced simulation code for alpha spectrometry  

E-print Network

A Monte Carlo code, known as AASI, is developed for simulating energy spectra in alpha spectrometry. The code documented here is a comprehensive package where all the major processes affecting the spectrum are included. A unique feature of the code is its ability to take into account coincidences between the particles emitted from the source. Simulations and measurements highlight the importance of coincidences in high-resolution alpha spectrometry. To show the validity of the simulated results, comparisons with measurements and other simulation codes are presented.

T. Siiskonen; R. Pollanen

2005-05-04

299

Environmental gamma-ray dose rate in Aomori Prefecture, Japan.  

PubMed

Japan's first commercial nuclear fuel cycling facilities, including a spent nuclear fuel reprocessing plant, are now under construction in Rokkasho, Aomori Prefecture (prefecture--an area of administration similar to a county in the U.S.). The reprocessing plant is due to be completed by 2004. We surveyed indoor and outdoor environmental gamma-ray dose rates throughout Aomori Prefecture from 1992 to 1996 to get background data before operation of the plant. Glass dosimeters were used to measure cumulative gamma-ray dose rate. The outdoor gamma-ray dose rates were measured at 109 locations in the prefecture. The indoor gamma-ray dose rates were measured at 81 locations, which were generally in a dwelling near the location of an outdoor measurement. The contribution of radionuclides in the ground to the outdoor dose rate was estimated by using in-situ gamma-ray spectrometry with a germanium detector. The spectra were measured at 20 locations used for the glass dosimeter measurements. The outdoor gamma-ray dose rate was higher in the Tsugaru area (western part of the prefecture) than in the Nanbu area (eastern part). Means of the dose rate were 28, 31, and 25 nGy h(-1) for the whole prefecture and Tsugaru and Nanbu areas, respectively. The dose rates in winter were lower than those in the other seasons due to the shielding effect of snow on the ground. Mean contributions of uranium series, thorium series and 40K to the dose rates were 7.7, 8.2, and 9.3 nGy h(-1), respectively. The indoor dose rate was generally higher than the outdoor one, and the mean ratio of indoor to outdoor dose rates was 1.42. Means of indoor gamma-ray dose rate were 41, 37, and 43 nGy h(-1) for the whole prefecture and Tsugaru and Nanbu areas, respectively. The average effective dose rate to people in the prefecture was estimated to be 0.24 mSv y(-1). PMID:11906142

Iyogi, Takashi; Ueda, Shinji; Hisamatsu, Shunichi; Kondo, Kunio; Haruta, Hideto; Katagiri, Hiromi; Kurabayashi, Mizumi; Nakamura, Yuji; Tsuji, Nobuo

2002-04-01

300

Gamma-ray peak shapes from cadmium zinc telluride detectors  

SciTech Connect

We report the results of a study of the peak shapes in the gamma spectra measured using several 5 x 5 x 5 mm{sup 3} cadmium zinc telluride (CZT) detectors. A simple parameterization involving a Gaussian and an exponential low energy tail describes the peak shapes sell. We present the variation of the parameters with gamma energy. This type of information is very useful in the analysis of complex gamma spectra consisting of many peaks.

Namboodiri, M.N.; Lavietes, A.D.; McQuaid, J.H.

1996-09-01

301

Fast atom bombardment tandem mass spectrometry of carotenoids  

SciTech Connect

Positive ion fast atom bombardment (FAB) tandem mass spectrometry (MS-MS) using a double-focusing mass spectrometer with linked scanning at constant B/E and high-energy collisionally activated dissociation (CAD) was used to differentiate 17 different cartenoids, including {beta}-apo-8{prime}- carotenal, astaxanthin, {alpha}-carotene, {beta}-carotene, {gamma}-carotene, {zeta}-carotene, canthaxanthin, {beta}-cryptoxanthin, isozeaxanthin bis (pelargonate), neoxanthin, neurosporene, nonaprene, lutein, lycopene, phytoene, phytofluene, and zeaxanthin. The carotenoids were either synthetic or isolated from plant tissues. The use of FAB ionization minimized degradation or rearrangement of the carotenoid structures due to the inherent thermal instability generally ascribed to these compounds. Instead of protonated molecules, both polar xanthophylls and nonpolar carotenes formed molecular ions, M{sup {center_dot}+}, during FAB ionization. Following collisionally activated dissociation, fragment ions of selected molecular ion precursors showed structural features indicative of the presence of hydroxyl groups, ring systems, ester groups, and aldehyde groups and the extent of aliphatic polyene conjugation. The fragmentation patterns observed in the mass spectra herein may be used as a reference for the structural determination of carotenoids isolated from plant and animal tissues. 18 refs., 4 figs.

van Breeman, R.B. [Univ. of Illinois, Chicago, IL (United States); Schmitz, H.H.; Schwartz, S.J. [North Carolina State Univ., Raleigh, NC (United States)

1995-02-01

302

The Universe Viewed in Gamma-Rays 1 Galactic Diffuse Gamma-ray Spectrum from Cosmic-ray In-  

E-print Network

The Universe Viewed in Gamma-Rays 1 Galactic Diffuse Gamma-ray Spectrum from Cosmic-ray In- teractions with Gas Clouds Michiko OHISHI and Masaki MORI Institute for Cosmic Ray Research, University, Australia Abstract Gamma-ray spectra from cosmic-ray proton and electron interactions with gas clouds have

Mori, Masaki

303

Beamstrahlung spectra in next generation linear colliders  

SciTech Connect

For the next generation of linear colliders, the energy loss due to beamstrahlung during the collision of the e{sup +}e{sup {minus}} beams is expected to substantially influence the effective center-of-mass energy distribution of the colliding particles. In this paper, we first derive analytical formulae for the electron and photon energy spectra under multiple beamstrahlung processes, and for the e{sup +}e{sup {minus}} and {gamma}{gamma} differential luminosities. We then apply our formulation to various classes of 500 GeV e{sup +}e{sup {minus}} linear collider designs currently under study.

Barklow, T.; Chen, P. (Stanford Linear Accelerator Center, Menlo Park, CA (United States)); Kozanecki, W. (DAPNIA-SPP, CEN-Saclay (France))

1992-04-01

304

Processing and classification of protein mass spectra.  

PubMed

Among the many applications of mass spectrometry, biomarker pattern discovery from protein mass spectra has aroused considerable interest in the past few years. While research efforts have raised hopes of early and less invasive diagnosis, they have also brought to light the many issues to be tackled before mass-spectra-based proteomic patterns become routine clinical tools. Known issues cover the entire pipeline leading from sample collection through mass spectrometry analytics to biomarker pattern extraction, validation, and interpretation. This study focuses on the data-analytical phase, which takes as input mass spectra of biological specimens and discovers patterns of peak masses and intensities that discriminate between different pathological states. We survey current work and investigate computational issues concerning the different stages of the knowledge discovery process: exploratory analysis, quality control, and diverse transforms of mass spectra, followed by further dimensionality reduction, classification, and model evaluation. We conclude after a brief discussion of the critical biomedical task of analyzing discovered discriminatory patterns to identify their component proteins as well as interpret and validate their biological implications. PMID:16463283

Hilario, Melanie; Kalousis, Alexandros; Pellegrini, Christian; Müller, Markus

2006-01-01

305

Single-protein nanomechanical mass spectrometry in real time  

PubMed Central

Nanoelectromechanical systems (NEMS) resonators can detect mass with exceptional sensitivity. Previously, mass spectra from several hundred adsorption events were assembled in NEMS-based mass spectrometry using statistical analysis. Here, we report the first realization of single-molecule NEMS-based mass spectrometry in real time. As each molecule in the sample adsorbs upon the NEMS resonator, its mass and the position-of-adsorption are determined by continuously tracking two driven vibrational modes of the device. We demonstrate the potential of multimode NEMS-based mass spectrometry by analyzing IgM antibody complexes in real-time. NEMS-MS is a unique and promising new form of mass spectrometry: it can resolve neutral species, provides resolving power that increases markedly for very large masses, and allows acquisition of spectra, molecule-by-molecule, in real-time. PMID:22922541

Hanay, M.S.; Kelber, S.; Naik, A.K.; Chi, D.; Hentz, S.; Bullard, E.C.; Colinet, E.; Duraffourg, L.; Roukes, M.L.

2012-01-01

306

Degree Spectra of Alexandra A.  

E-print Network

Degree Spectra of Structures Alexandra A. Soskova DEGREE SPECTRA OF STRUCTURES CO-SPECTRA OF STRUCTURES PROPERTIES OF THE DEGREE SPECTRA AND CO-SPECTRA RELATIVE SPECTRA OF STRUCTURES PROPERTIES OF RELATIVE SPECTRA Degree Spectra of Structures Alexandra A. Soskova Faculty of Mathematics and Computer

Haase, Markus

307

Gamma-Ray Burst Lines  

E-print Network

The evidence for spectral features in gamma-ray bursts is summarized. As a guide for evaluating the evidence, the properties of gamma-ray detectors and the methods of analyzing gamma-ray spectra are reviewed. In the 1980's, observations indicated that absorption features below 100 keV were present in a large fraction of bright gamma-ray bursts. There were also reports of emission features around 400 keV. During the 1990's the situation has become much less clear. A small fraction of bursts observed with BATSE have statistically significant low-energy features, but the reality of the features is suspect because in several cases the data of the BATSE detectors appear to be inconsistent. Furthermore, most of the possible features appear in emission rather than the expected absorption. Analysis of data from other instruments has either not been finalized or has not detected lines.

Michael S. Briggs

1999-10-20

308

Night Spectra Quest.  

ERIC Educational Resources Information Center

Presents the Night Spectra Quest, a pocket-sized chart that identifies in color the spectra of all the common night lights and has an integrally mounted, holographic diffraction grating to look through. (JRH)

Jacobs, Stephen

1995-01-01

309

Automatic Quality Assessment of Peptide Tandem Mass Spectra  

Microsoft Academic Search

Motivation: A powerful proteomics methodology couples high-performance liquid chromatography (HPLC) with tandem mass spectrometry and database-search software, such as SEQUEST. Such a set-up, however, produces a large num- ber of spectra, many of which are of too poor quality to be useful. Hence a filter that eliminates poor spectra before the database search can significantly improve throughput and robustness. Moreover,

Marshall W. Bern; David Goldberg; W. Hayes Mcdonald; John R. Yates III

2004-01-01

310

DEGREE SPECTRA OF STRUCTURES JOINT SPECTRA OF STRUCTURES  

E-print Network

DEGREE SPECTRA OF STRUCTURES JOINT SPECTRA OF STRUCTURES MINIMAL PAIRS QUASI-MINIMAL DEGREE Minimal for Joint Spectra #12;DEGREE SPECTRA OF STRUCTURES JOINT SPECTRA OF STRUCTURES MINIMAL PAIRS QUASI-MINIMAL DEGREE DEGREE SPECTRA OF STRUCTURES Degree Spectra of Structures Let A = (N; R1, . . . , Rk

Soskova, Alexandra A.

311

DEGREE SPECTRA OF STRUCTURES JOINT SPECTRA OF STRUCTURES  

E-print Network

DEGREE SPECTRA OF STRUCTURES JOINT SPECTRA OF STRUCTURES PROPERTIES OF JOINT SPECTRA Properties of the Joint Spectra of Sequence of Structures Alexandra A. Soskova Department of Mathematics and Computer of Structures #12;DEGREE SPECTRA OF STRUCTURES JOINT SPECTRA OF STRUCTURES PROPERTIES OF JOINT SPECTRA

Soskova, Alexandra A.

312

before and after gamma irradiation  

NASA Astrophysics Data System (ADS)

A series of samples of HoFe1- x Ni x O3 ( x = 0.0, 0.1, 0.3) were prepared using the solid-state reaction technique to understand the structural, dielectric and conductivity properties before and after gamma irradiation of accumulated dose of 625 KGy. The X-ray diffraction confirms that all the samples exist in single-phase orthorhombic structure having space group Pbnm. With increasing dopant Ni, the unit cell volume and lattice parameters undergo small change. X-ray analysis show change in the interplanar spacing and full width at half maximum values after gamma irradiation. The Raman spectra of the samples show modifications after gamma irradiation. It can be easily seen that after gamma irradiation intensity, peak width are completely altered by gamma-absorbed dose. Measurement of dielectric loss and dielectric constant at room temperature was performed before and after gamma irradiation in the frequency range of 20 Hz-1 MHz. It is observed that the value of dielectric constant decreases after irradiation. The ac conductivity is estimated from the dielectric constant and loss tangent. Exposure to gamma radiation results in substantial modification in the physical properties of the Ni-doped Ho-based orthoferrites.

Habib, Zubida; Ikram, M.; Majid, Kowsar; Asokan, K.

2014-09-01

313

Peak Height Precision in Hadamard Transform Time-of-Flight Mass Spectra  

E-print Network

Peak Height Precision in Hadamard Transform Time-of-Flight Mass Spectra Joel R. Kimmel,* Oh Kyu University, Stanford, California, USA Hadamard transform (HT) time-of-flight mass spectrometry (TOFMS­1130) © 2005 American Society for Mass Spectrometry H adamard transform time-of-flight mass spec- trometry (HT

Zare, Richard N.

314

Fast Kernel Discriminant Analysis for Classification of Liver Cancer Mass Spectra  

Microsoft Academic Search

The classification of serum samples based on mass spectrometry (MS) has been increasingly used for monitoring disease progression and for diagnosing early disease. However, the classification task in mass spectrometry data is extremely challenging due to the very huge size of peaks (features) on mass spectra. Linear discriminant analysis (LDA) has been widely used for dimension reduction and feature extraction

Jung Hun Oh; Jean Gao

2011-01-01

315

Cosmic gamma-ray bursts  

NASA Technical Reports Server (NTRS)

A review of the cosmic gamma-ray burst phenomenon is presented. Both the light curves and the energy spectra of these short transient events display a great diversity. However, rapid rise times and periodicities sometimes observed in the light curves suggest a compact object origin. Similarly, absorption and emission features in the energy spectra argue strongly in favor of this interpretation. Counterparts to gamma-bursters in other energy ranges, such as optical and sort x-ray, have still not been identified, however, leading to a large uncertainty in the distances to bursters. Although gamma-ray burst sources have not yet been observed to repeat, numerous bursts from three objects which may be related to the gamma-bursters, called Soft Gamma Repeaters, have been recorded; there is weak evidence that they may be relatively distant on a galactic scale. Future missions, particularly those emphasizing high energy, time, and/or spatial resolution, as well as a multiwavelength approach, are likely to advance our understanding of this enigmatic phenomenon.

Hurley, K.

1991-01-01

316

Feature Extraction and Analysis of Ovarian Cancer Proteomic Mass Spectra  

Microsoft Academic Search

The use of mass spectrometry(MS) as a analytical tool in proteomics is poised to revolutionize early cancer detection and biomarker identification. Although proteomic mass spectra has shown the promising potential of finding disease-related protein patterns, key challenges remain in the processing of them especially for the curse of dimensionality. In the present study, an alternative approach to feature extraction from

Hui Meng; Wenxue Hong; Jialin Song; Liqiang Wang

2008-01-01

317

Gamma Knife  

MedlinePLUS

... Gamma Knife® and its associated computerized treatment planning software enable physicians to locate and irradiate relatively small ... that the imaging and treatment planning computers and software are correct and acceptable. The mechanical functions of ...

318

High-Resolution Fast-Neutron Spectrometry for Arms Control and Treaty Verification  

SciTech Connect

Many nondestructive nuclear analysis techniques have been developed to support the measurement needs of arms control and treaty verification, including gross photon and neutron counting, low- and high-resolution gamma spectrometry, time-correlated neutron measurements, and photon and neutron imaging. One notable measurement technique that has not been extensively studied to date for these applications is high-resolution fast-neutron spectrometry (HRFNS). Applied for arms control and treaty verification, HRFNS has the potential to serve as a complimentary measurement approach to these other techniques by providing a means to either qualitatively or quantitatively determine the composition and thickness of non-nuclear materials surrounding neutron-emitting materials. The technique uses the normally-occurring neutrons present in arms control and treaty verification objects of interest as an internal source of neutrons for performing active-interrogation transmission measurements. Most low-Z nuclei of interest for arms control and treaty verification, including 9Be, 12C, 14N, and 16O, possess fast-neutron resonance features in their absorption cross sections in the 0.5- to 5-MeV energy range. Measuring the selective removal of source neutrons over this energy range, assuming for example a fission-spectrum starting distribution, may be used to estimate the stoichiometric composition of intervening materials between the neutron source and detector. At a simpler level, determination of the emitted fast-neutron spectrum may be used for fingerprinting 'known' assemblies for later use in template-matching tests. As with photon spectrometry, automated analysis of fast-neutron spectra may be performed to support decision making and reporting systems protected behind information barriers. This paper will report recent work at Idaho National Laboratory to explore the feasibility of using HRFNS for arms control and treaty verification applications, including simulations and experiments, using fission-spectrum neutron sources to assess neutron transmission through composite low-Z attenuators.

David L. Chichester; James T. Johnson; Edward H. Seabury

2012-07-01

319

The use of low-level liquid scintillation spectrometry for rapid measurement and decision making  

SciTech Connect

Liquid scintillation spectrometry (LSC) has proved over the last fifteen years to be an excellent tool for low-level counting of beta- and alpha-particle emitters. Using low-level instruments the determination of, for instance {sup 90}Sr, could be considerably simplified in the laboratory, saving time and also money for chemicals and manpower. Furthermore, low-level instruments have been successfully used for measurements when fast analysis was required. The four instruments (Quantulus, Wallac Oy), that the author uses, have not only very low background, which cuts measurement time considerably; but from the pulse- height spectra much information about the nature of the radionuclides present and the absence of specific radionuclides can be extracted. From the absence of high-energy beta-particle activity in the pulse-height spectra of precipitation in the first days after the Chernobyl accident the author could draw the conclusion, that practically no {sup 90}Y was present and therefore only small amounts of {sup 90}Sr, if any, could be expected in precipitation and later in food. This enabled them to make the decision not to waste time with a large number of {sup 90}Sr analyses. Large numbers of drinking water samples could be screened for contamination much more sensitively and faster than by gamma-ray spectrometry. More examples will be presented of cases where rapid information was needed; how contamination and nuclear installations can be easily checked and how LSC helped to cut down the time required, the manpower and the costs for radon measurements and environmental surveillance.

Schoenhofer, F. [Federal Inst. for Food Control and Research (Austria)

1998-12-31

320

Physical constraints on models of gamma-ray bursters  

SciTech Connect

This report deals with the constraints that can be placed on models of gamma-ray burst sources based on only the well-established observational facts and physical principles. The premise is developed that the very hard x-ray and gamma-ray continua spectra are well-established aspects of gamma-ray bursts. Recent theoretical work on gamma-ray bursts are summarized with emphasis on the geometrical properties of the models. Constraints on the source models which are implied by the x-ray and gamma-ray spectra are described. The allowed ranges for the luminosity and characteristic dimension for gamma-ray burst sources are shown. Some of the deductions and inferences about the nature of the gamma-ray burst sources are summarized. 67 refs., 3 figs.

Epstein, R.I.

1985-01-01

321

International Journal of Mass Spectrometry 248 (2006) 18 Molecular hydrogen ion elimination from alkyl iodides  

E-print Network

is studied by means of time-of-flight mass spectrometry. The study has been performed by using 60 fs ( = 800 alkyl iodides by means of time-of-flight (TOF) mass spectrometry under strong (1016 W cm-2) femtosecond hydrogen ion (H2 +) in the mass spectra of many organic compounds under strong laser irradia- tion has been

Strathclyde, University of

322

International Journal of Mass Spectrometry 292 (2010) 3847 Contents lists available at ScienceDirect  

E-print Network

desorption ionization time-of-flight (MALDI-TOF) mass spectra were obtained in a new matrix, 4International Journal of Mass Spectrometry 292 (2010) 38­47 Contents lists available at ScienceDirect International Journal of Mass Spectrometry journal homepage: www.elsevier.com/locate/ijms ESI and MALDI mass

323

RAPID COMMUNICATIONS IN MASS SPECTROMETRY Rapid Commun. Mass Spectrom. 2005; 19: 24812487  

E-print Network

of matrix-assisted laser desorption/ ionization photodissociation tandem time-of-flight mass spectra time-of- flight (TOF) mass spectrometry of ions generated by matrix-assisted laser desorption compatible with tandem time-of-flight (TOF) mass spectrometry for ions generated by matrix-assisted laser

Kim, Myung Soo

324

MALDI-TOF Mass Spectrometry Analysis of Amphipol-Trapped Membrane Proteins  

E-print Network

by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI in mass spectra. Thus, the combination of MP stabilization by APols and MS analyses providesMALDI-TOF Mass Spectrometry Analysis of Amphipol-Trapped Membrane Proteins Cherine Bechara

325

PepHMM: A Hidden Markov Model Based Scoring Function for Mass Spectrometry Database Search  

E-print Network

of mass spectrometry data is essential for all applications that are based on this techniquePepHMM: A Hidden Markov Model Based Scoring Function for Mass Spectrometry Database Search Yunhu. Although many mathematical models have been proposed to score peptides against tandem mass spectra, our

Chen, Ting

326

Nuclear Magnetic Resonance Spectrometry.  

ERIC Educational Resources Information Center

Reviews current research in NMR spectrometry, in the areas of apparatus and techniques, spectral analysis, computer applications, analytical applications, and selected organic and inorganic systems. Various aspects of NMR spectrometry are presented in tabular form, with 133 references. Listed also are 124 references from the discussions in the…

Wasson, John R.; Salinas, Jorge E.

1980-01-01

327

Gas Chromatography -Mass Spectrometry  

E-print Network

GCMS - 1 Gas Chromatography - Mass Spectrometry GC-MS ANALYSIS OF ETHANOL AND BENZENE IN GASOLINE Last updated: June 17, 2014 #12;GCMS - 2 Gas Chromatography - Mass Spectrometry GC-MS ANALYSIS). The goal of this experiment is to separate the components in a sample of gasoline using Gas Chromatography

Nizkorodov, Sergey

328

DEGREE SPECTRA OF STRUCTURES RELATIVE SPECTRA OF STRUCTURES  

E-print Network

DEGREE SPECTRA OF STRUCTURES RELATIVE SPECTRA OF STRUCTURES PROPERTIES OF RELATIVE SPECTRA Degree Spectra of Structures Alexandra A. Soskova Faculty of Mathematics and Computer Science Sofia University Leeds Logic Seminar Alexandra A. Soskova Degree Spectra of Structures #12;DEGREE SPECTRA OF STRUCTURES

Soskova, Alexandra A.

329

Spectra of stable sonoluminescence  

NASA Astrophysics Data System (ADS)

The continuous emission of picosecond pulses of light has been observed to originate from a bubble trapped at the pressure antinode of a resonant sound field in water and in water/glycerin mixtures. The spectra of this light in several solutions has been measured with a scanning monochrometer/photomultiplier detector system. The spectra are broadband and show strong emission in the UV region. A comparison of this measurement to two other independently produced spectra is made. The spectra are also modeled by a blackbody radiation distribution to determine an effective blackbody temperature and a size is deduced as if Sonoluminescence were characterized by blackbody radiation.

Lewis, Stephen D.

1992-12-01

330

Study of gamma-ray strength functions  

SciTech Connect

The use of gamma-ray strength function systematics to calculate neutron capture cross sections and capture gamma-ray spectra is discussed. The ratio of the average capture width, GAMMA/sub ..gamma../-bar, to the average level spacing, D/sub obs/, both at the neutron separation energy, can be derived from such systematics with much less uncertainty than from separate systematics for values of GAMMA/sub ..gamma../-bar and D/sub obs/. In particular, the E1 gamma-ray strength function is defined in terms of the giant dipole resonance (GDR). The GDR line shape is modeled with the usual Lorentzian function and also with a new energy-dependent, Breit-Wigner (EDBW) function. This latter form is further parameterized in terms of two overlapping resonances, even for nuclei where photonuclear measurements do not resolve two peaks. In the mass ranges studied, such modeling is successful for all nuclei away from the N = 50 closed neutron shell. Near the N = 50 shell, a one-peak EDBW appears to be more appropriate. Examples of calculated neutron capture excitation functions and capture gamma-ray spectra using the EDBW form are given for target nuclei in the mass-90 region and also in the Ta-Au mass region. 20 figures.

Gardner, D.G.; Gardner, M.A.; Dietrich, F.S.

1980-08-07

331

Gamma-Ray Spectrometric Characterization of Overpacked CC104\\/107 RH-TRU Wastes: Surrogate Tests  

Microsoft Academic Search

Development of the gamma-ray spectrometric technique termed GSAK (Gamma-Ray Spectrometry with Acceptable Knowledge) for the characterization of CC104\\/107 remote-handled transuranic (RH-TRU) wastes continued this year. Proof-of-principle measurements have been completed on the surrogate RH-TRU waste drums configured earlier this year. The GSAK technique uses conventional gamma-ray spectrometry to quantify the detectable fission product content of overpacked RH-TRU drums. These results

J. K. Hartwell; R. T. Klann; M. E. McIlwain

2000-01-01

332

Reproducibility of Temperature-Selected Mass Spectra in Matrix-Assisted Laser Desorption Ionization of Peptides  

E-print Network

desorption ionization (MALDI)1-4 combined with time-of-flight (TOF) mass spectrometry is one of the mostReproducibility of Temperature-Selected Mass Spectra in Matrix- Assisted Laser Desorption experiment, a set of mass spectra was collected by repetitive irradiation of a spot on a sample. Even though

Kim, Myung Soo

333

Modeling and simulation of infrared reflectance spectra of deep trench structures of DRAM  

Microsoft Academic Search

This paper proposes a nondestructive technique for measuring deep trench structures of DRAM using infrared reflectance spectrometry. By processing layered-film optical model equivalents of various trench array structures with effective medium theory, the reflectance spectra of optical models are accurately simulated with Fresnel's reflection equations, and the relationships between modeled spectra and trench geometric parameters are analyzed. It is fully

Chuanwei Zhang; Shiyuan Liu; Tielin Shi; Huayong Gu

2008-01-01

334

Charge state determination of peptide tandem mass spectra using support vector machine (SVM)  

Microsoft Academic Search

A single mass spectrometry experiment could produce hundreds of thousands of tandem mass spectra. Several search engines have been developed to interpret tandem mass spectra. All search engines need to determine the masses of peptide ions from mass\\/charge ratios of ions. Unfortunately, mass spectrometers do not detect the charges of ions. A current strategy is to search candidate peptides multiply

An-min Zou; Jiarui Ding; Jin-hong Shi; Fang-xiang Wu

2008-01-01

335

Charge state determination of peptide tandem mass spectra using support vector machine (SVM)  

Microsoft Academic Search

A single mass spectrometry experiment could produce hundreds of thousands of tandem mass spectra. Several search engines have been developed to interpret tandem mass spectra. All search engines need to determine the masses of peptide ions from their mass\\/charge ratios. Unfortunately, mass spectrometers do not detect the charges of ions. A current strategy is to search candidate peptides multiple times,

An-Min Zou; Jin-Hong Shi; Jiarui Ding; Fang-Xiang Wu

2010-01-01

336

The influence of structural features on facile McLafferty-type, even-electron rearrangements in tandem mass spectra of carboxylate anions.  

PubMed

In contrast to the well-described McLafferty rearrangement in odd-electron cations, relatively little has been reported on comparable rearrangements in even-electron ions, especially negative ions. This work reports a systematic study using tandem mass spectrometry (MS/MS) fragment ion spectra of carboxylate anions having a suitably acidic proton in the gamma position. The rearrangement process was studied in both ion trap and triple quadrupole mass spectrometers; characteristic enolate anions and stable neutral products were formed at low collision energies. The process has diagnostic and analytical potential in, for example, the analysis of peptides having C-terminal serine residues and of 3-hydroxy- or 3-aminocarboxylic acids in complex mixtures. PMID:16628561

Grossert, J Stuart; Cook, Matthew C; White, Robert L

2006-01-01

337

High LET, passive space radiation dosimetry and spectrometry  

Microsoft Academic Search

The development of high linear energy transfer (LET), passive radiation dosimetry and spectrometry is needed for the purpose of accurate determination of equivalent doses and assessment of health risks to astronauts on long duration missions. Progress in the following research areas is summerized: intercomparisons of cosmic ray equivalent dose and LET spectra measurements between STS missions and between astronauts; increases

E. V. Benton; A. L. Frank; E. R. Benton; R. P. Keegan; L. A. Frigo; D. Sanner; V. Rowe

1995-01-01

338

Hyphenation of chromatography and FT-IR spectrometry  

SciTech Connect

The challenge of establishing the identities of environmental samples has been met by a combination of chromatography and FT-IR spectrometry. The separative powers of chromatography combined with the very large library of IR spectra yields both qualitative and quantitative information. The advent of microcomputers has advanced significantly the computational powers of modestly prices systems.

Griffiths, P.R.; Pentoney, S.L. Jr.; Giorgetti, A.; Shafer, K.H.

1986-11-01

339

JOURNAL OF MASS SPECTROMETRY J. Mass Spectrom. 2003; 38: 277282  

E-print Network

-capture dissociation; FTICR, Fourier transform ion cyclotron resonance; Q-TOF, quadrupole time-of-flight nanoelectrospray ionization tandem mass spectra. Owing to the accurate molecular mass of the intact proteinJOURNAL OF MASS SPECTROMETRY J. Mass Spectrom. 2003; 38: 277­282 Published online 24 January 2003

Manstein, Dietmar J.

340

Atmospheric Pressure Molecular Imaging by Infrared MALDI Mass Spectrometry  

E-print Network

was developed for an orthogonal acceleration time-of-flight mass spectrometer and utilized to analyze peptides to the ultraviolet laser shots, spatially correlated mass spectra are acquired. Application of MALDI imaging to largeAtmospheric Pressure Molecular Imaging by Infrared MALDI Mass Spectrometry Yue Li, Bindesh Shrestha

Vertes, Akos

341

Libraries of Stellar Spectra  

NSDL National Science Digital Library

This is a guide to online and abstract libraries of stellar spectra. This reference list also includes information about the spectra of Late-M, L, and T Dwarf stars, Morgan-Keenan spectral classification, the solar spectrum, spectrophotometric atlases, and automated and neural network classification.

2005-04-25

342

Combinatorial Approaches for Mass Spectra Recalibration  

Microsoft Academic Search

Mass spectrometry has become one of the most popular analysis techniques\\u000d\\u000a\\u0009in Proteomics and Systems Biology. With the creation of larger datasets,\\u000d\\u000a\\u0009the automated recalibration of mass spectra becomes important to\\u000d\\u000a\\u0009ensure that every peak in the sample spectrum is correctly assigned\\u000d\\u000a\\u0009to some peptide and protein. Algorithms for recalibrating mass spectra\\u000d\\u000a\\u0009have to be robust with respect to wrongly

Sebastian Bocker; Veli Makinen

2008-01-01

343

Action spectra again?  

PubMed

Action spectroscopy has a long history and is of central importance to photobiological studies. Action spectra were among the first assays to point to chlorophyll as the molecule most responsible for plant growth and to DNA as the genetic material. It is useful to construct action spectra early in the investigation of new areas of photobiological research in an attempt to determine the wavelength limits of the radiation region causing the studied response. But due to the severe absorption of ultraviolet (UV) radiation by biological samples, UV action spectra were first limited to small cells (bacteria and fungi). Advances in techniques (e.g. single cell culture) and analysis allowed accurate action spectra to be reported even for mammalian cells. But precise analytical action spectra are often difficult to obtain when large, pigmented, or groups of cells are investigated. Here some action spectra are limited in interpretation and merely supply a wavelength vs effect curve. When polychromatic sources are employed, the interpretation of action spectra is even more complex and formidable. But such polychromatic action spectra can be more directly related to ambient responses. Since precise action spectra usually require the completion of a relatively large number of careful experiments using somewhat sophisticated equipment over a range of at least six wavelengths, they are often not pursued. But they remain central to the elucidation of the effect being studied. The worldwide community has agreed that stratospheric ozone is depleting, with the possibility of a consequent rise in the amount of UV-B (290-320 nm) reaching the earth's surface. It is therefore essential that new action spectra be completed for UV-B effects on a large variety of responses of human, animal, and aquatic plant systems. Combining these action spectra with the known amounts of UV-B reaching the biosphere can give rise to solar UV effectiveness spectra that, in turn, can give rise to estimates of effect. Preliminary estimates suggest that ozone layer depletion may seriously impact such important biological end-points as skin cancer, cataracts, the immune system, crop yields, and oceanic phytoplankton. So action spectra continue to play a central role in important photobiological research. PMID:1798760

Coohill, T P

1991-11-01

344

Targeted quantitation of proteins by mass spectrometry.  

PubMed

Quantitative measurement of proteins is one of the most fundamental analytical tasks in a biochemistry laboratory, but widely used immunochemical methods often have limited specificity and high measurement variation. In this review, we discuss applications of multiple-reaction monitoring (MRM) mass spectrometry, which allows sensitive, precise quantitative analyses of peptides and the proteins from which they are derived. Systematic development of MRM assays is permitted by databases of peptide mass spectra and sequences, software tools for analysis design and data analysis, and rapid evolution of tandem mass spectrometer technology. Key advantages of MRM assays are the ability to target specific peptide sequences, including variants and modified forms, and the capacity for multiplexing that allows analysis of dozens to hundreds of peptides. Different quantitative standardization methods provide options that balance precision, sensitivity, and assay cost. Targeted protein quantitation by MRM and related mass spectrometry methods can advance biochemistry by transforming approaches to protein measurement. PMID:23517332

Liebler, Daniel C; Zimmerman, Lisa J

2013-06-01

345

Standardization and denoising algorithms for mass spectra to classify whole-organism bacterial specimens  

Microsoft Academic Search

Motivation: Application of mass spectrometry in proteomics is a breakthrough in high-throughput analyses. Early appli- cations have focused on protein expression profiles to differ- entiate among various types of tissue samples (e.g. normal versus tumor). Here our goal is to use mass spectra to differ- entiate bacterial species using whole-organism samples. The raw spectra are similar to spectra of tissue

Glen A. Satten; Somnath Datta; Hercules Moura; Adrian R. Woolfitt; Maria Da G. Carvalho; George M. Carlone; Barun K. De; Antonis Pavlopoulos; John R. Barr

2004-01-01

346

The gamma 1 and gamma 3 bands of (16)O3: Line positions and intensities  

NASA Technical Reports Server (NTRS)

Using 0.005/cm-resolution Fourier transform spectra of samples of ozone, the gamma 1 and gamma 3 bands of (16)O3 have been reanalyzed to obtain accurate line positions and an extended set of upper state rotational levels (J up to 69, K sub a up to 20). Combined with the available microwave data, these upper state rotational levels were satisfactorily fitted using a Hamiltonian which takes explicitly into account the strong Coriolis interaction affecting the rotational levels of these two interacting states. In addition, 350 relative line intensities were measured from which the rotational expansions of the transition moment operators for the gamma 1 and gamma 3 states have been deduced. Finally, a complete listing of line positions, intensities, and lower state energies of the gamma 1 and gamma 3 bands of (16)O3 has been generated.

Flaud, J.-M.; Camy-Peyret, C.; Devi, V. Malathy; Rinsland, C. P.; Smith, M. A. H.

1988-01-01

347

[Gamma knife].  

PubMed

The term "radiosurgery" was defined by Lars Leksell, a Swedish neurosurgeon, as the closed-skull destruction of a precisely defined intracranial target using high-dose radiation with stereotactic technique in a single session. For this purpose, the Gamma Knife was developed in 1968. It was equipped with multiple cobalt 60 sources and delivered collimated narrow radiation beams precisely concentrated to the focus. The dose gradient in the periphery of the treatment volume is extremely steep, so a high dose can be delivered to the small target volume sparing the surrounding normal tissue. Treatment planning was directed using a computer program developed for Gamma Knife and stereotactically obtained imaging database. The treatment procedure may be completed in only one day. The Gamma Knife makes it possible to treat deep-seated and surgically inaccessible lesions with low mortality and morbidity, and to control conventionally radioresistant lesions. Up to now, over 10,000 patients have undergone radiosurgery with a Gamma Knife around the world. The indications were primarily functional disorders, then expanded to include arterio-venous malformation (AVM), benign and a few malignant brain tumors. Excellent results were noted in the treatment of AVM. The two-year total obliteration rate of the nidus was 71-87%, and the adverse effect rate was 3-12%. The control rates of acoustic tumors was reportedly 85-89% with a lower incidence of facial nerve injury and a higher rate of hearing preservation. Gamma Knife radiosurgery has also been used to treat meningioma, pituitary adenoma and metastatic brain tumors. Its application for the treatment of malignant glial tumors or other tumors is developing. The capability of this technique is growing, and radiosurgery will be one of the important treatment modalities for selected neurosurgical or other pathological conditions. PMID:8239677

Terahara, A

1993-11-01

348

Discrimination of multilocus sequence typing-based Campylobacter jejuni subgroups by MALDI-TOF mass spectrometry  

PubMed Central

Background Campylobacter jejuni, the most common bacterial pathogen causing gastroenteritis, shows a wide genetic diversity. Previously, we demonstrated by the combination of multi locus sequence typing (MLST)-based UPGMA-clustering and analysis of 16 genetic markers that twelve different C. jejuni subgroups can be distinguished. Among these are two prominent subgroups. The first subgroup contains the majority of hyperinvasive strains and is characterized by a dimeric form of the chemotaxis-receptor Tlp7m+c. The second has an extended amino acid metabolism and is characterized by the presence of a periplasmic asparaginase (ansB) and gamma-glutamyl-transpeptidase (ggt). Results Phyloproteomic principal component analysis (PCA) hierarchical clustering of MALDI-TOF based intact cell mass spectrometry (ICMS) spectra was able to group particular C. jejuni subgroups of phylogenetic related isolates in distinct clusters. Especially the aforementioned Tlp7m+c+ and ansB+/ ggt+ subgroups could be discriminated by PCA. Overlay of ICMS spectra of all isolates led to the identification of characteristic biomarker ions for these specific C. jejuni subgroups. Thus, mass peak shifts can be used to identify the C. jejuni subgroup with an extended amino acid metabolism. Conclusions Although the PCA hierarchical clustering of ICMS-spectra groups the tested isolates into a different order as compared to MLST-based UPGMA-clustering, the isolates of the indicator-groups form predominantly coherent clusters. These clusters reflect phenotypic aspects better than phylogenetic clustering, indicating that the genes corresponding to the biomarker ions are phylogenetically coupled to the tested marker genes. Thus, PCA clustering could be an additional tool for analyzing the relatedness of bacterial isolates. PMID:24195572

2013-01-01

349

Statistics and Its Interface Volume 2 (2009) 329340 Alignment of protein mass spectrometry data by  

E-print Network

Statistics and Its Interface Volume 2 (2009) 329­340 Alignment of protein mass spectrometry data of the misalignment spectra by a factor of around 75%. Most alignment algorithms align spectra by clustering neighbor-axis of a spectrum is the inten- sity (relative abundance) of protein/peptide, the x-axis the mass-to-charge ratio

Feng, Yang

350

Algorithmen in der Massenspektrometrie-basierten Proteomforschung Algorithms in mass spectrometry based proteomics  

E-print Network

- mental methods and important concepts. 2. Initial data processing of mass spectra and LC-MS data and proteins 2 Isotope distributions This exposition is based on: · R. Martin Smith: Understanding Mass Spectra. Mass spectrometry (and liquid chromatography) based methods in proteomics. Introduction to experi

Spang, Rainer

351

Very High Energy Gamma Ray Extension of GRO Observations  

NASA Technical Reports Server (NTRS)

The membership, progress, and invited talks, publications, and proceedings made by the Whipple Gamma Ray Collaboration is reported for june 1990 through May 1994. Progress was made in the following areas: the May 1994 Markarian Flare at Whipple and EGRET (Energetic Gamma Ray Experiment Telescope) energies; AGN's (Active Galactic Nuclei); bursts; supernova remnants; and simulations and energy spectra.

Weekes, Trevor C.

1994-01-01

352

The particle-gamma coincidence method: A brief introduction  

SciTech Connect

Excitation energy information from particle detectors can significantly improve the analysis process of {gamma}-ray spectra and result in more detailed nuclear structure information. Therefore, a new setup at the HORUS {gamma}-ray spectrometer at the University of Cologne has been installed, housing silicon particle detectors at up to eight positions.

Mayer, J.; Derya, V.; Endres, J.; Hennig, A.; Netterdon, L.; Pascu, S.; Pickstone, S. G.; Sauerwein, A.; Scholz, P.; Spieker, M.; Streit, T.-M.; Zilges, A. [Institute for Nuclear Physics, University of Cologne (Germany)

2013-06-10

353

Spectra over complex terrain  

SciTech Connect

Spectra have been measured over land downwind of a water surface, over hilltops and escarpments, and over rolling farmland. The following hypotheses can be used to explain the differences between these spectra. (1) For wavelengths short compared to the fetch over the new terrain, spectral densities are in equilibrium with the new terrain. (2) For wavelengths long compared to this fetch, spectral densities remain unchanged if the ground is horizontal. If the flow is over a steep hill, the low-frequency structure is modified by distortion of the mean flow, with the longitudinal component losing energy relative to the lateral and vertical components. Because vertical-velocity spectra contain relatively less low-frequency energy than horizontal-velocity spectra, energetic vertical-velocity fluctuations tend to be in equilibrium with local terrain.

Panofsky, H.A.; Larko, D.; Lipschutz, R.; Stone, G.

1981-01-01

354

Recommended standards for gamma-ray energy calibration  

Microsoft Academic Search

A consistent set of gamma-ray energies, generally with uncertainties of less than 10ppm, has been prepared for use in the energy calibration of gamma-ray spectra. The energy scale used for the previously recommended standards (1979) has been modified to take into account subsequent adjustments in the fundamental constants (-7.71ppm) and in the gamma-ray wavelengths deduced from a revised estimate of

R. G. Helmer; C. van der Leun

1999-01-01

355

Recommended standards for gamma-ray energy calibration (1999)  

Microsoft Academic Search

A consistent set of gamma-ray energies, generally with uncertainties of less than 10ppm, is recommended for use in the energy calibration of gamma-ray spectra. The energy scale used for the previously recommended standards (1979) has been modified to take into account subsequent adjustments in the fundamental constants (-7.71ppm) and in the gamma-ray wavelengths deduced from a revised estimate of the

R. G. Helmer; C. van der Leun

2000-01-01

356

Neutron-Capture gamma Rays from Various Elements  

Microsoft Academic Search

Neutron-capture gamma-ray spectra have been measured in the energy range 0.3 to 3 Mev by means of a two-crystal Compton scintillation spectrometer. The efficiency of the instrument as a function of energy was determined experimentally. The uniqueness of the 2.23-Mev gamma ray following capture of a neutron by hydrogen has been confirmed, and this gamma ray was used as a

T. H. Braid

1956-01-01

357

Non-thermal radiative pair plasmas: processes and spectra  

E-print Network

We study the emission and absorption spectra due to various photon and pair processes in a non-equilibrium pair plasma containing a significant density of photons. We present here some preliminary results from Monte-Carlo simulations. These investigations are likely to be useful in understanding the radiation and relaxation mechanisms in non-thermal gamma-ray sources in astrophysics.

Ravi P. Pilla; Jacob Shaham

1995-05-17

358

Measurement of the {sup 157}Gd(n,{gamma}) reaction with the DANCE {gamma} calorimeter array  

SciTech Connect

The {sup 157}Gd(n,{gamma}) reaction was measured with the DANCE {gamma} calorimeter (consisting of 160 BaF{sub 2} scintillation detectors) at the Los Alamos Neutron Science Center. The multiplicity distributions of the {gamma} decay were used to determine the resonance spins up to E{sub n}=300 eV. The {gamma}-ray energy spectra for different multiplicities were measured for the s-wave resonances. The shapes of these spectra were compared with simulations based on the use of the DICEBOX statistical model code. Simulations showed that the scissors mode is required not only for the ground-state transitions but also for transitions between excited states.

Chyzh, A.; Dashdorj, D. [North Carolina State University, Raleigh, North Carolina 27695, USA, andTriangle Universities Nuclear Laboratory, Durham, North Carolina 27708 (United States); Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Baramsai, B.; Mitchell, G. E.; Walker, C. L. [North Carolina State University, Raleigh, North Carolina 27695 (United States) andTriangle Universities Nuclear Laboratory, Durham, North Carolina 27708 (United States); Becker, J. A.; Parker, W.; Wu, C. Y. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Becvar, F.; Kroll, J.; Krticka, M. [Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, CZ-180 00 Prague 8 (Czech Republic); Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2011-07-15

359

Computational mass spectrometry for small molecules  

PubMed Central

The identification of small molecules from mass spectrometry (MS) data remains a major challenge in the interpretation of MS data. This review covers the computational aspects of identifying small molecules, from the identification of a compound searching a reference spectral library, to the structural elucidation of unknowns. In detail, we describe the basic principles and pitfalls of searching mass spectral reference libraries. Determining the molecular formula of the compound can serve as a basis for subsequent structural elucidation; consequently, we cover different methods for molecular formula identification, focussing on isotope pattern analysis. We then discuss automated methods to deal with mass spectra of compounds that are not present in spectral libraries, and provide an insight into de novo analysis of fragmentation spectra using fragmentation trees. In addition, this review shortly covers the reconstruction of metabolic networks using MS data. Finally, we list available software for different steps of the analysis pipeline. PMID:23453222

2013-01-01

360

Computational mass spectrometry for small molecules.  

PubMed

: The identification of small molecules from mass spectrometry (MS) data remains a major challenge in the interpretation of MS data. This review covers the computational aspects of identifying small molecules, from the identification of a compound searching a reference spectral library, to the structural elucidation of unknowns. In detail, we describe the basic principles and pitfalls of searching mass spectral reference libraries. Determining the molecular formula of the compound can serve as a basis for subsequent structural elucidation; consequently, we cover different methods for molecular formula identification, focussing on isotope pattern analysis. We then discuss automated methods to deal with mass spectra of compounds that are not present in spectral libraries, and provide an insight into de novo analysis of fragmentation spectra using fragmentation trees. In addition, this review shortly covers the reconstruction of metabolic networks using MS data. Finally, we list available software for different steps of the analysis pipeline. PMID:23453222

Scheubert, Kerstin; Hufsky, Franziska; Böcker, Sebastian

2013-01-01

361

Multiphoton effects in coherent radiation spectra  

NASA Astrophysics Data System (ADS)

At measurements of the spectra of intense gamma radiation produced by ultrarelativistic electrons in periodic structures, pileup of arrivals to the detector of several photons from one electron can cause significant deviations of the measured spectrum from the classically evaluated one. The description of experiments then requires summation of all multiphoton contributions. We describe the corresponding resummation procedure for the photon spectral intensity, as well as for the photon multiplicity spectrum, and apply it to the study of radiation spectra with a mix of coherent and incoherent contributions. The impact of multiphoton effects on the radiation spectrum shape is investigated. The limit of high photon multiplicity for the coherent part of the radiation is explored in detail. A method for reconstruction of the underlying single-photon spectrum from the multiphoton one is formulated.

Bondarenco, M. V.

2014-07-01

362

A Grid Service Based on Suffix Trees for Pattern Extraction from Mass Spectrometry Proteomics Data  

Microsoft Academic Search

The paper presents a Grid Service allowing to detect and extract the longest common sub-spectrum among a set of mass spectrometry\\u000a spectra data. The system uses a novel pattern extraction algorithm named LCSS (Longest Common Spectra SubString) that adapts\\u000a a very popular string matching technique based on Suffix Trees to spectra data. The basic LCSS algorithm made available as\\u000a a

Mario Cannataro; Pierangelo Veltri

2006-01-01

363

A gamma-gamma coincidence/anticoincidence spectrometer for low-level cosmogenic (22)Na/(7)Be activity ratio measurement.  

PubMed

In this study, a digital gamma-gamma coincidence/anticoincidence spectrometer was developed and examined for low-level cosmogenic (22)Na and (7)Be in air-filter sample monitoring. The spectrometer consists of two bismuth germanate scintillators (BGO) and an XIA LLC Digital Gamma Finder (DGF)/Pixie-4 software and card package. The spectrometer design allows a more selective measurement of (22)Na with a significant background reduction by gamma-gamma coincidence events processing. Hence, the system provides a more sensitive way to quantify trace amounts of (22)Na than normal high resolution gamma spectrometry providing a critical limit of 3 mBq within a 20 h count. The use of a list-mode data acquisition technique enabled simultaneous determination of (22)Na and (7)Be activity concentrations using a single measurement by coincidence and anticoincidence mode respectively. PMID:24412563

Zhang, Weihua; Ungar, Kurt; Stukel, Matthew; Mekarski, Pawel

2014-04-01

364

Fourier Transform Mass Spectrometry  

PubMed Central

This article provides an introduction to Fourier transform-based mass spectrometry. The key performance characteristics of Fourier transform-based mass spectrometry, mass accuracy and resolution, are presented in the view of how they impact the interpretation of measurements in proteomic applications. The theory and principles of operation of two types of mass analyzer, Fourier transform ion cyclotron resonance and Orbitrap, are described. Major benefits as well as limitations of Fourier transform-based mass spectrometry technology are discussed in the context of practical sample analysis, and illustrated with examples included as figures in this text and in the accompanying slide set. Comparisons highlighting the performance differences between the two mass analyzers are made where deemed useful in assisting the user with choosing the most appropriate technology for an application. Recent developments of these high-performing mass spectrometers are mentioned to provide a future outlook. PMID:21742802

Scigelova, Michaela; Hornshaw, Martin; Giannakopulos, Anastassios; Makarov, Alexander

2011-01-01

365

Nevan Krogan: Mass Spectrometry  

NSDL National Science Digital Library

This lecture from the iBioSeminars project, presented by Nevan Krogan of the Department of Cellular and Molecular Pharmacology at UC-San Francisco, covers mass spectrometry and its application to molecular biology. Mass spectrometry is a powerful tool for elucidating the elemental composition of a sample or molecule. More recently, it has been used to characterize biological material, in particular proteins and protein complexes, in a variety of organisms. This lecture will review the underlying principles of how a mass spectrometer works, discuss up to date instrumentation that is presently being used in the biological research setting and provide specific examples of how mass spectrometry is being used to reveal functional insight into different biological systems. The video runs 27:36 and can be downloaded in a number of formats: QuickTime, MP4, M4V, and PPT. The video can also be streamed through YouTube or iTunes U.

Krogan, Nevan

2013-07-12

366

Target-decoy search strategy for increased confidence in large-scale protein identifications by mass spectrometry  

Microsoft Academic Search

Liquid chromatography and tandem mass spectrometry (LC-MS\\/MS) has become the preferred method for conducting large-scale surveys of proteomes. Automated interpretation of tandem mass spectrometry (MS\\/MS) spectra can be problematic, however, for a variety of reasons. As most sequence search engines return results even for 'unmatchable' spectra, proteome researchers must devise ways to distinguish correct from incorrect peptide identifications. The target-decoy

Joshua E Elias; Steven P Gygi

2007-01-01

367

WebSpectra  

NSDL National Science Digital Library

This site, created by Barry C. Fam and Craig A. Merlic of the University of California - Los Angeles, was established to provide chemistry students with a library of spectroscopy problems. Interpretation of spectra is a technique that requires practice - this site provides 1H NMR and 13C NMR, DEPT, COSY and IR spectra of various compounds for students to interpret. Hopefully, these problems will provide a useful resource to better understand spectroscopy. The page was given a "Top 5% Chemistry Site" award for its usefulness and content. This is a great resource for anyone interested in either biochemistry or chemistry.

Fam, Barry C.; Merlic, Craig A.

2009-05-07

368

Analysis of deteriorated rubber-based pressure sensitive adhesive by pyrolysis-gas chromatography\\/mass spectrometry and attenuated total reflectance Fourier transform infrared spectrometry  

Microsoft Academic Search

Rubber-based pressure sensitive adhesives of three packing tapes were exposed to sunlight for 6 months to accelerate the oxidation of the adhesives. The exposed adhesives and the unexposed adhesives were analyzed by attenuated total reflectance Fourier transform infrared spectrometry (ATR\\/FT-IR) and pyrolysis-gas chromatography\\/mass spectrometry (Py-GC\\/MS). The ATR\\/FT-IR spectra and the pyrograms changed drastically after the exposure. The pyrolyzate peaks of

Y. Kumooka

2006-01-01

369

B American Society for Mass Spectrometry, 2011 DOI: 10.1007/s13361-011-0115-y  

E-print Network

­806, Korea Abstract Time-of-flight (TOF) mass spectra for a peptide (Y6) were obtained by utilizing matrix (MALDI) [1­ 5]/time-of-flight (TOF) mass spectrometry is useful for labile biological moleculesB American Society for Mass Spectrometry, 2011 DOI: 10.1007/s13361-011-0115-y J. Am. Soc. Mass

Kim, Myung Soo

370

Electrons and protons separation in the GAMMA-400 experiment  

NASA Astrophysics Data System (ADS)

The GAMMA-400 gamma-ray telescope is intended to measure the fluxes of gamma-rays and cosmic-ray electrons and positrons in the energy range from 100 MeV to several TeV. Such measurements concern with the following scientific tasks: search for signatures of dark matter, investigation of point sources of gamma-rays, studies of the energy spectra of Galactic and extragalactic diffuse emission, studies of gamma-ray bursts and gamma-ray emission from the Sun, as well as high precision measurements of spectra of high-energy electrons and positrons, protons and nuclei up to the knee. The main components of cosmic rays are protons and helium nuclei, whereas the part of lepton component in total flux is ~10^-3 for high energies. In present paper the capability of the GAMMA-400 gamma-ray telescope to distinguish electrons and positrons from protons in cosmic rays is investigated. The separate investment in proton rejection is studied for each detector system of the GAMMA-400 gamma-ray telescope. Using combined information from all detector systems allow us to provide rejection from protons with factor of ~4×10^5 for vertical incident particles and ~3×10^5 for particles with initial inclination of 30 deg.

Leonov, Alexey

371

Development of {gamma}-ray detectors for {sup 16}O(p,p'{gamma}) experiment  

SciTech Connect

The {gamma} ray production in neutral-current (NC) neutrino-oxygen interaction is very important to the detection of neutrinos from supernova explosion in a neutrino experiment, since those {gamma} rays can become extra signals or unexpected background in the energy region from 5 MeV to 30 MeV. We propose the experiment to measure {gamma} rays in {sup 16}O(p,p') reaction at Research Center for Nuclear Physics (RCNP, Osaka) to provide good information on the {gamma}-ray emission spectra in neutrino-oxygen reactions. We present the design of {gamma}-ray detectors (NaI, CsI, HPGe), which will be used in proposed experiment.

Mori, T.; Izumi, T.; Ou, I.; Yano, T.; Sakuda, M.; Tamii, A.; Suzuki, T.; Yosoi, M. [Department of physiscs, Okayama University, Okaymaa 700-8530 (Japan); Research Center for Nuclear Physics (RCNP), Ibaraki, Osaka 567-0047 (Japan)

2012-11-12

372

Investigation of {gamma} radiation from {sup 178}Hf in the respective (n, n Prime {gamma}) reaction  

SciTech Connect

The spectra and angular distributions of gamma rays were measured in the reaction {sup 178}Hf(n, n Prime {gamma}) induced by a beam of fast reactor neutrons. Data onmultipole mixtures in gamma transitions and a lot of new information about gamma transitions of energy 1.5 to 3.0 MeV were obtained. A comparison of these results with information known from the respective (n, {gamma}) reaction made it possible to refine the schemes of deexcitation of {sup 178}Hf levels at energies above 1.5 MeV, to determine more precisely features of these levels, and to introduce new levels and rotation bands at excitation energies of about 2MeV.

Govor, L. I.; Demidov, A. M.; Kurkin, V. A., E-mail: kurkin@polyn.kiae.su; Mikhailov, I. V. [National Research Center Kurchatov Institute (Russian Federation)

2012-12-15

373

Gamma, Beta, Erf  

NSDL National Science Digital Library

This page includes the encyclopedia entries for gamma, beta and erf functions including factorials, binomials, gamma functions and inverses, differentiated gamma functions, beta functions and inverses, probability integrals and inverses, Frensnel integrals and exponential integrals.

374

Mass Spectrometry Primer  

NSDL National Science Digital Library

This website developed by Waters Corporation provides a brief primer on mass spectrometry which includes information on instrumentation, a discussion of mass accuracy, resolution, and LC-MS. As such the site should be a valuable resource for both students and faculty.

2011-06-13

375

Fourier Transform Mass Spectrometry.  

ERIC Educational Resources Information Center

Discusses the nature of Fourier transform mass spectrometry and its unique combination of high mass resolution, high upper mass limit, and multichannel advantage. Examines its operation, capabilities and limitations, applications (ion storage, ion manipulation, ion chemistry), and future applications and developments. (JN)

Gross, Michael L.; Rempel, Don L.

1984-01-01

376

Feature Extraction for Classification of Proteomic Mass Spectra: A Comparative Study  

Microsoft Academic Search

To satisfy the ever growing need for effective screening and diagnostic tests, medical practitioners have turned their attention\\u000a to high resolution, high throughput methods. One approach is to use mass spectrometry based methods for disease diagnosis.\\u000a Effective diagnosis is achieved by classifying the mass spectra as belonging to healthy or diseased individuals. Unfortunately,\\u000a the high resolution mass spectrometry data contains

Ilya Levner; Vadim Bulitko; Guohui Lin

377

MASS SPECTROMETRY IN ENVIRONMENTAL SCIENCES  

EPA Science Inventory

This review covers applications of mass spectrometry to the environmental sciences. From the early applications of mass spectrometry to environmental research in the 1960s and 1970s, mass spectrometry has played an important role in aiding our understanding of environmental poll...

378

Solar flare gamma-ray line shapes  

NASA Technical Reports Server (NTRS)

A computer code has been developed which is used to calculate ab initio the laboratory shapes and energy shifts of gamma-ray lines from (C-12)(p, gamma/4.438/)p-prime(C-12) and (O-16)(p, gamma/6.129/)p-prime(O-16) reactions and to calculate the expected shapes of these lines from solar flares. The sensitivity of observable solar flare gamma-ray line shapes to the directionality of the incident particles is investigated for several projectile angular distributions. Shapes of the carbon and oxygen lines are calculated assuming realistic proton energy spectra for particles in circular orbits at the mirror points of magnetic loops, for particle beams directed downward into the photosphere, and for isotropic particle distributions. Line shapes for flare sites near the center of the sun and on the limb are shown for both thin-target and thick-target interaction models.

Werntz, C.; Kim, Y. E.; Lang, Frederick L.

1990-01-01

379

Spectral measurements of direct and scattered gamma radiation at a boiling-water reactor site  

Microsoft Academic Search

Quantitative surveys of direct and scattered gamma radiation emitted from the steam-power conversion systems of a boiling-water reactor and other on-site radiation sources were made using a directionally shielded HPGe gamma spectrometry system. The purpose of this study was to obtain data on the relative contributions and energy distributions of direct and scattered gamma radiation in the site environs. The

R. C. Block; I. L. Preiss; R. M. Ryan; G. J. Vargo

1990-01-01

380

ICRM intercomparison of the relative gamma-ray emission probabilities of 75Se  

Microsoft Academic Search

There are a number of discrepancies in the reported gamma-ray emission probabilities of 75Se. An international work programme was proposed and agreed by members of the Beta- and Gamma-ray Spectrometry Working Group (SWG) of the International Committee for Radionuclide Metrology (ICRM) to study these data. The first step has been the measurement and intercomparison of the relative gamma-ray emission rates,

R. Jedlovszky; L. Sz'´ucs; Á. Szörényi

1990-01-01

381

Photon-photon absorption and the uniqueness of the spectra of active galactic nuclei  

NASA Technical Reports Server (NTRS)

The effects of the feedback of e(+)-e(-) pair reinjection in a plasma due to photon-photon absorption of its own radiation was examined. Under the assumption of continuous electron injection with a power law spectrum E to the minus gamma power and Compton losses only, it is shown that for gamma 2 the steady state electron distribution function has a unique form independent of the primary injection spectrum. This electron distribution function can, by synchrotron emission, reproduce the general characteristics of the observed radio to optical active galactic nuclei spectra. Inverse Compton scattering of the synchrotron photons by the same electron distribution can account for their X-ray spectra, and also implies gamma ray emission from these objects. This result is invoked to account for the similarity of these spectra, and it is consistent with observations of the diffuse gamma ray background.

Kazanas, D.

1984-01-01

382

Extracting Efficient Fuzzy If-Then Rules from Mass Spectra of Blood Samples to Early Diagnosis of Ovarian Cancer  

Microsoft Academic Search

Among the many applications of mass spectrometry, biomarker pattern discovery from protein mass spectra has aroused huge interest in the recent years. While research efforts have raised hopes of early and less invasive diagnosis, they have also brought to light the many issues to be tackled before mass-spectra-based proteomic patterns become routine clinical tools. Undoubtedly, biomarker selection among the high

Amin Assareh; Mohammad Hassan Moradi

2007-01-01

383

Localization of inclusions in multiple prompt gamma ray analysis: a feasibility study  

NASA Astrophysics Data System (ADS)

We investigate the feasibility of using low energy gamma rays from neutron capture to localize slabs inside samples. A new system based on two gamma ray detectors with 2D collimators to be tested at the INES beamline at the pulsed neutron source ISIS (Oxford, UK) is described. The system provides a localization of slabs inside extended samples by using gamma ray self-absorption. Geant4 Monte Carlo simulations of the beamline were carried out to model gamma spectra from test samples.

Miceli, A.; Festa, G.; Senesi, R.; Gorini, G.; Andreani, C.

2013-12-01

384

On the origin of the particle fluxes from the thunderclouds: Energy spectra analysis  

NASA Astrophysics Data System (ADS)

Simultaneous measurements of the gamma ray differential energy spectra, electric field disturbances, and meteorological conditions provided by experimental facilities located at Mt. Aragats in Armenia allows to establish the model of particle acceleration and propagation in thunderstorm atmosphere. We present comparisons of measured and modeled thunderstorm ground enhancements (TGEs). The origin of the majority of TGEs is the MOS process —the modification of energy spectra of cosmic ray electrons in the atmospheric electric fields. The gamma ray differential energy spectra are well described by the power law function with indexes in the range -1.5\\div-2.5 for the electric field strengths 0.8-1.5 kV/cm at altitudes of 3400-5000 m a.s.l. The good agreement of the characteristics of experimental and simulated TGEs gives hope to estimate the intracloud electric field by the observed parameters of TGE gamma ray energy spectra.

Chilingarian, A.; Hovsepyan, G.; Vanyan, L.

2014-06-01

385

Low background germanium planar detector for gamma-ray spectrometry  

NASA Astrophysics Data System (ADS)

A new ultra-low background planar germanium spectrometer has been developed. The planar geometry improves the sensitivity and energy resolution below 600 keV. The integral background counting rate in the Laboratoire Souterrain de Modane (4800 m water equivalent) in the energy range from 20 to 1500 keV for the planar Ge (mass=800 g) is 140 count/day. After 40 days of statistics, the background counting rates for all expected single lines are below 0.5 count/day with the exception of 210Pb(46-keV line) which was measured to be (1.76±0.25) count/day. Monte Carlo simulations have been performed to explain the origin of the remaining background and to calculate the detection efficiencies. Sensitivities around 1 mBq/kg are obtained within few days of statistics for 226Ra and 228Th. The main achievement is the high sensitivities for 210Pb (46-keV line) and 238U ( 234Th: 63 and 93 keV lines). For an aluminium sample (mass=1 kg) the limits obtained in 15 days are 210Pb<9 mBq/kg and 238U<3 mBq/kg.

Loaiza, P.; Chassaing, C.; Hubert, Ph.; Nachab, A.; Perrot, F.; Reyss, J.-L.; Warot, G.

2011-04-01

386

Recent progress in low-level gamma imaging  

SciTech Connect

The CEA's Aladin gamma imaging system has been operated successfully for several years in nuclear plants and during decommissioning projects with additional tools such as gamma spectrometry detectors and dose rate probes. The radiological information supplied by these devices is becoming increasingly useful for establishing robust and optimized decommissioning scenarios. Recent technical improvements allow this gamma imaging system to be operated in low-level applications and with shorter acquisition times suitable for decommissioning projects. The compact portable system can be used in places inaccessible to operators. It is quick and easy to implement, notably for onsite component characterization. Feasibility trials and in situ measurements were recently carried out under low-level conditions, mainly on waste packages and glove boxes for decommissioning projects. This paper describes recent low-level in situ applications. These characterization campaigns mainly concerned gamma emitters with {gamma} energy < 700 keV. In many cases, the localization of hot spots by gamma camera was confirmed by additional measurements such as dose rate mapping and gamma spectrometry measurements. These complementary techniques associated with advanced calculation codes (MCNP, Mercure 6.2, Visiplan and Siren) offer a mobile and compact tool for specific assessment of waste packages and glove boxes. (authors)

Mahe, C.; Girones, Ph.; Lamadie, F.; Le Goaller, C. [CEA/DEN/DDCO/SDSP, CEA/Valrho, BP 17171, 30207 Bagnols sur Ceze Cedex (France)

2007-07-01

387

On the capabilities of isotope dilution alpha spectrometry in the determination of plutonium concentration  

NASA Astrophysics Data System (ADS)

The determination of plutonium in spent fuel solution by isotope dilution alpha spectrometry (IDAS) is described. Two aliquots of spent fuel solution were separately spiked with well characterized solutions of 238Pu and 239Pu. The pure spiked and unspiked plutonium solutions were obtained using a partition chromatographic technique. The alpha activity ratios of {238Pu}/{(239Pu+240Pu)} have been measured by alpha spectrometry and the concentration of plutonium calculated using isotopic composition data from mass spectrometry measurements. In parallel, the plutonium concentration was also determined by isotope dilution mass spectrometry (IDMS). The main aim of this experiment was to show the capability of IDAS compared to IDMS. Therefore the factors affecting the precision and accuracy of the IDAS method are discussed in detail. Also the outline of IDAS based exclusively on radiometric measurements (isotopic composition of plutonium by gamma spectrometry) is presented and its capabilities discussed.

Parus, J.; Raab, W.; Swietly, H.; Cappis, J.; Deron, S.

1992-02-01

388

Parmeterization of spectra  

NASA Technical Reports Server (NTRS)

Following reception and analog to digital conversion (A/D) conversion, atmospheric radar backscatter echoes need to be processed so as to obtain desired information about atmospheric processes and to eliminate or minimize contaminating contributions from other sources. Various signal processing techniques have been implemented at mesosphere-stratosphere-troposphere (MST) radar facilities to estimate parameters of interest from received spectra. Such estimation techniques need to be both accurate and sufficiently efficient to be within the capabilities of the particular data-processing system. The various techniques used to parameterize the spectra of received signals are reviewed herein. Noise estimation, electromagnetic interference, data smoothing, correlation, and the Doppler effect are among the specific points addressed.

Cornish, C. R.

1983-01-01

389

Measurement of Grüneisen parameter of tissue by photoacoustic spectrometry  

NASA Astrophysics Data System (ADS)

The Grüneisen parameter of tissue is a constitutive parameter in photoacoustic tomography. Here, we applied photoacoustic spectrometry (PAS) to directly measure the Grüneisen parameter. In our PAS system, laser pulses at wavelengths between 460 and 1600 nm were delivered to tissue samples, and photoacoustic signals were detected by a 20 MHz flat water-immersion ultrasonic transducer. By fitting photoacoustic spectra to light absorption spectra, we found that the Grüneisen parameter was 0.73 for porcine subcutaneous fat tissue, and 0.15 for oxygenated bovine red blood cells at room temperature (24°C).

Yao, Da-Kang; Wang, Lihong V.

2013-03-01

390

Observations of Gamma-Ray Bursts  

NASA Technical Reports Server (NTRS)

Some basic observed properties of gamma-ray bursts are reviewed. Although some properties were known 25 years ago, new and more detailed observations have been made by the Compton Observatory in the past three years. The new observation with the greatest impact has been the observed isotropic distribution of bursts along with a deficiency of weak bursts which would be expected from a homogeneous burst distribution. This is not compatible with any known Galactic population of objects. Gamma-ray bursts show an enormous variety of burst morphologies and a wide spread in burst durations. The spectra of gamma-ray bursts are characterized by rapid variations and peak power which is almost entirely in the gamma-ray energy range. Delayed gamma-ray burst photons extending to GeV energies have been detected for the first time. A time dilation effect has also been reported to be observed in gamma-ray, bursts. The observation of a gamma-ray burst counterpart in another wavelength region has yet to be made.

Fishman, G. J.

1995-01-01

391

The essence on mass spectrometry based microbial diagnostics.  

PubMed

In recent years, matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometry has become an important bioanalytical method to detect profiles of proteins and peptides derived from whole bacterial cells. This accurate molecular-phenotypic method can be easily applied to robustly detect bacteria on the genus, species and in some cases on the subspecies level. Standardised laboratory protocols for the preparation of abundant bacterial proteins and the development of tailored data analysis software, as well as high-quality databases of microbial reference mass spectra, made the procedure attractive to replace phenotypic or biochemical procedures for identification of bacteria and other microorganisms. Moreover, genotypic and functional mass spectrometry based methods to detect for example bacterial strains or antibiotic resistance may become useful in the coming years. In general, mass spectrometry is a powerful tool to facilitate routine microbial diagnostics. PMID:22410108

Kliem, Magdalena; Sauer, Sascha

2012-06-01

392

High energy gamma ray astronomy  

NASA Technical Reports Server (NTRS)

The SAS-2 gamma ray experiment and its detection of celestial gamma rays are described. Data also cover intensity of high energy gamma rays, gamma ray distribution, gamma ray origin, and diffuse radiation.

Fichtel, C. E.

1974-01-01

393

Cross sections and differential spectra for reactions of 2-20 MeV neutrons of /sup 27/Al  

SciTech Connect

This report summarizes product yields, secondary n,p and ..cap alpha.. spectra, and ..gamma..-ray spectra calculated for incident neutrons of 2-20 MeV on /sup 27/Al targets. Results are all from the code ALICE, using the version ALISO which does weighting of results for targets which are a mix of isotopes. Where natural isotopic targets are involved, yields and n,p,..cap alpha.. spectra will be reported weighted over isotopic yields. Gamma-ray spectra, however, will be reported for the most abundant isotope.

Blann, M.; Komoto, T.T.

1988-01-01

394

Beamstrahlung spectra in next generation linear colliders. Revision  

SciTech Connect

For the next generation of linear colliders, the energy loss due to beamstrahlung during the collision of the e{sup +}e{sup {minus}} beams is expected to substantially influence the effective center-of-mass energy distribution of the colliding particles. In this paper, we first derive analytical formulae for the electron and photon energy spectra under multiple beamstrahlung processes, and for the e{sup +}e{sup {minus}} and {gamma}{gamma} differential luminosities. We then apply our formulation to various classes of 500 GeV e{sup +}e{sup {minus}} linear collider designs currently under study.

Barklow, T.; Chen, P. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Kozanecki, W. [DAPNIA-SPP, CEN-Saclay (France)

1992-04-01

395

Neutron and photon spectrometry in monoenergetic neutron fields  

Microsoft Academic Search

In monoenergetic neutron fields (144keVspectrometry was performed for prompt photons as well as for scattered neutrons and for neutrons produced by nuclear reactions. Time-of-flight (TOF) experiments with NE213 scintillation detectors were carried out, and spectral fluences were obtained from the unfolding of the measured pulse height spectra. Doses of the prompt photons were calculated and compared with those obtained

S. Neumann; R. Böttger; S. Guldbakke; M. Matzke; W. Sosaat

2002-01-01

396

Ground-based passive FT-IR spectrometry  

Microsoft Academic Search

Absorbance and transmittance spectra were acquired with ground-based passive FT-IR spectrometry for industrial stack evaluations and open-air controlled vapor generation experiments. The industrial stack effluents of sulfur dioxide and nitrous oxide were detected from a coal-burning power plant and an acid plant, respectively, with both MWIR and LWIR passive sensors. The controlled open-air experiments relied on only a LWIR sensor.

Robert B. Knapp; Roger J. Combs; Robert T. Kroutil

2002-01-01

397

IR and NIR spectrometry characterizations of LGS crystal and family  

Microsoft Academic Search

Middle and near infrared (MIR\\/NIR) spectrometry has been used to characterize series of samples of LGx family and GaPO{4}. Since OH impurities influence the material properties, their spectroscopy is investigated in detail. The [190 3200 nm] region is measured in transmission. Furthermore, the study of spectra made at Nitrogen liquid temperature is used to follow the modification in the signature

M. Assoud; J. J. Boy; K. Yamni; A. Albizane

2005-01-01

398

Charge Prediction of Lipid Fragments in Mass Spectrometry  

SciTech Connect

An artificial neural network is developed for predicting which fragment is charged and which fragment is neutral for lipid fragment pairs produced from a liquid chromatography tandem mass spectrometry simulation process. This charge predictor is integrated into software developed at PNNL for in silico spectra generation and identification of metabolites known as Met ISIS. To test the effect of including charge prediction in Met ISIS, 46 lipids are used which show a reduction in false positive identifications when the charge predictor is utilized.

Schrom, Brian T.; Kangas, Lars J.; Ginovska, Bojana; Metz, Thomas O.; Miller, John H.

2011-12-18

399

Criteria for the identification of compounds by liquid chromatography–mass spectrometry and liquid chromatography–multiple mass spectrometry in forensic toxicology and doping analysis  

Microsoft Academic Search

In contrast to GC–MS, many factors are influencing mass spectra of organic compounds when analyzed by LC–MS. In-source or transport collision-induced dissociation by electrospray ionization or atmospheric pressure chemical ionization demonstrate the need for experimental condition standardization when building-up a library of reference spectra. Magnetic sector, quadrupole, ion trap or time-of-flight filters placed on single or multiple mass spectrometry instruments

Laurent Rivier

2003-01-01

400

Biological Cluster Mass Spectrometry  

PubMed Central

This article reviews the new physics and new applications of secondary ion mass spectrometry using cluster ion probes. These probes, particularly C60, exhibit enhanced molecular desorption with improved sensitivity owing to the unique nature of the energy-deposition process. In addition, these projectiles are capable of eroding molecular solids while retaining the molecular specificity of mass spectrometry. When the beams are microfocused to a spot on the sample, bioimaging experiments in two and three dimensions are feasible. We describe emerging theoretical models that allow the energy-deposition process to be understood on an atomic and molecular basis. Moreover, experiments on model systems are described that allow protocols for imaging on biological materials to be implemented. Finally, we present recent applications of imaging to biological tissue and single cells to illustrate the future directions of this methodology. PMID:20055679

Winograd, Nicholas; Garrison, Barbara J.

2010-01-01

401

Underwater gamma surveys of Mururoa and Fangataufa lagoons.  

PubMed

Underwater gamma-ray spectrometry is an effective alternative or complement to traditional sampling and laboratory analyses for applications such as contamination assessment in emergency situations, long-term monitoring of radioactive releases or investigation of sunken radioactive objects. This technique was recently used in a seabed contamination study undertaken at the South Pacific nuclear weapons test sites of the Mururoa and Fangataufa atolls in order to guide and focus sediment core sampling in the areas with highest gamma-emitting radionuclide levels. 60Co inventories estimated on the basis of the underwater gamma-ray spectrometry survey were in good agreement with results previously obtained by traditional sediment sampling and laboratory analysis. PMID:10568282

Osvath, I; Povinec, P; Huynh-Ngoc, L; Comanducci, J F

1999-09-30

402

Direct analysis of cannabis samples by desorption atmospheric pressure photoionization-mass spectrometry.  

PubMed

Fast analysis of cannabis samples without prior sample preparation or chromatography was performed using desorption atmospheric pressure photoionization-mass spectrometry (DAPPI-MS). The MS(2) spectra of the molecular ions of tetrahydrocannabinol (THC) and cannabidiol (CBD) formed in DAPPI-MS showed distinct product ions, unlike the protonated molecules formed with other ambient mass spectrometry techniques, making possible the reliable identification of THC from cannabis samples. PMID:22977002

Kauppila, Tiina J; Flink, Anu; Laakkonen, Ulla-Maija; Aalberg, Laura; Ketola, Raimo A

2013-03-01

403

Probabilistic Disease Classification of Expression-Dependent Proteomic Data from Mass Spectrometry of Human Serum  

Microsoft Academic Search

We have developed an algorithm called Q5 for probabilistic classification of healthy vs. disease whole serum samples using mass spectrometry. The algorithm employs Principal Components Analysis (PCA) followed by Linear Discriminant Analysis (LDA) on whole spectrum Surface- Enhanced Laser Desorption\\/Ionization Time of Flight (SELDI-TOF) Mass Spectrometry (MS) data, and is demonstrated on four real datasets from complete, complex SELDI spectra

Ryan H. Lilien; Hany Farid; Bruce Randall Donald

2003-01-01

404

A method to correct differential nonlinearities in subranging analog-to-digital converters used for digital gamma-ray spectroscopy  

E-print Network

The influence on $\\gamma$-ray spectra of differential nonlinearities (DNL) in subranging, pipelined analog-to-digital converts (ADCs) used for digital $\\gamma$-ray spectroscopy was investigated. The influence of the DNL error on the $\\gamma$-ray spectra, depending on the input count-rate and the dynamic range has been investigated systematically. It turned out, that the DNL becomes more significant in $\\gamma$-ray spectra with larger dynamic range of the spectroscopy system. An event-by-event offline correction algorithm was developed and tested extensively. This correction algorithm works especially well for high dynamic ranges.

Hennig, A; Hennig, W; Pascovici, G; Warr, N; Weinert, M; Zilges, A

2014-01-01

405

A method to correct differential nonlinearities in subranging analog-to-digital converters used for digital gamma-ray spectroscopy  

E-print Network

The influence on $\\gamma$-ray spectra of differential nonlinearities (DNL) in subranging, pipelined analog-to-digital converts (ADCs) used for digital $\\gamma$-ray spectroscopy was investigated. The influence of the DNL error on the $\\gamma$-ray spectra, depending on the input count-rate and the dynamic range has been investigated systematically. It turned out, that the DNL becomes more significant in $\\gamma$-ray spectra with larger dynamic range of the spectroscopy system. An event-by-event offline correction algorithm was developed and tested extensively. This correction algorithm works especially well for high dynamic ranges.

A. Hennig; C. Fransen; W. Hennig; G. Pascovici; N. Warr; M. Weinert; A. Zilges

2014-06-04

406

Investigation of {gamma}/{gamma}{prime} lattice mismatch in the polycrystalline nickel-base superalloy IN738LC: Influence of heat treatment and creep deformation  

SciTech Connect

The {gamma}/{gamma}{prime} lattice misfit in the polycrystalline nickel-base superalloy IN738LC has been determined by convergent beam electron diffraction (CBED) technique in a transmission electron microscope (TEM). The influence of heat treatment and creep deformation on the misfit was investigated. The chemical compositions of the {gamma} and {gamma}{prime} phases were analyzed with the help of Energy Dispersive Spectrometry (EDS). The influence of different heat treatments on the {gamma}/{gamma}{prime} misfit can be explained in terms of the dependence of the chemical compositions of {gamma} and {gamma}{prime} phases on the heat treatments. The creep deformation causes a tetragonal distortion in {gamma}{prime} precipitates and leads to considerable changes in the misfit. The tetragonality in {gamma}{prime} phase and the evolution of the misfit during creep process can be understood on the basis of a dislocation model. An estimation of the local internal stress in {gamma}{prime} phase generated by {gamma}/{gamma}{prime} interfacial dislocations formed during creep deformations shows it to be higher than the applied stress.

Li, J.; Wahi, R.P. [Hahn-Meitner-Inst. Berlin GmbH (Germany)] [Hahn-Meitner-Inst. Berlin GmbH (Germany)

1995-02-01

407

A Novel Preprocessing Method Using Hilbert Huang Transform for MALDI-TOF and SELDI-TOF Mass Spectrometry Data  

Microsoft Academic Search

MotivationMass spectrometry is a high throughput, fast, and accurate method of protein analysis. Using the peaks detected in spectra, we can compare a normal group with a disease group. However, the spectrum is complicated by scale shifting and is also full of noise. Such shifting makes the spectra non-stationary and need to align before comparison. Consequently, the preprocessing of the

Li-Ching Wu; Hsin-Hao Chen; Jorng-Tzong Horng; Chen Lin; Norden E. Huang; Yu-Che Cheng; Kuang-Fu Cheng; William C. S. Cho

2010-01-01

408

IMPLEMENTING THE STANDARD SPECTRUM METHOD FOR ANALYSIS OF ?-? COINCIDENCE SPECTRA  

SciTech Connect

The standard deconvolution analysis tool (SDAT) algorithms were developed and tested at the University of Texas at Austin. These algorithms utilize the standard spectrum technique for spectral analysis of {beta}-{gamma} coincidence spectra for nuclear explosion monitoring. Work has been conducted under this contract to implement these algorithms into a useable scientific software package with a graphical user interface. Improvements include the ability to read in PHD formatted data, gain matching, and data visualization. New auto-calibration algorithms were developed and implemented based on 137Cs spectra for assessment of the energy vs. channel calibrations. Details on the user tool and testing are included.

Biegalski, S.; Flory, Adam E.; Schrom, Brian T.; Ely, James H.; Haas, Derek A.; Bowyer, Ted W.; Hayes, James C.

2011-09-14

409

Multiparameter liquid scintillation spectrometry  

NASA Astrophysics Data System (ADS)

Multiparameter analog to digital conversion and multichannel pulse height analyses, enabling simultaneous acquisition of four different 1024 ch energy spectra, enhance the accuracy of low-level counting of 3H and 14C. The new LS spectrometer, the QUANTULUS, is based on the concept of "total optimisation" where all known factors enabling reduction of background and data validation have been considered. These involve: special counting vials, random access — variable time base — sequential counting, electronic background reduction, and a " master spectra" library with continuous monitoring of user selected validity parameters by high resolution MCA.

Polach, Henry; Kojola, Hannu; Nurmi, Jarmo; Soini, Erkki

1984-11-01

410

Spectra From Space : Main Menu  

NSDL National Science Digital Library

On-line science lesson (grades 7 - 9) - students learn about satellite spectra research, electromagnetic spectrum, do hands-on activities. In this lesson students investigate satellite missions operating in four electromagnetic bands. Students learn about spectra and why satellites gather certain kinds of spectra from space by using the Internet and doing hands-on activities. From the University of California, Berkeley.

1997-01-01

411

Relationship between in-source and post-source fragment ions in the matrix-assisted laser desorption (ionization) mass spectra of carbohydrates recorded with reflectron time-of-flight mass spectrometers 1 1 Dedicated to Brian Green for his many innovative contributions to mass spectrometry instrument development and for his tireless help in teaching us how to take advantage of them  

Microsoft Academic Search

The reflectron matrix-assisted laser desorption (ionization) [MALD(I)] mass spectra of many complex carbohydrates (and other compounds) recorded with time-of-flight (TOF) instruments fitted with time-lag focusing (delayed extraction) contain focused fragment ions resulting from fragmentation within the ion source, together with unfocused (metastable) fragments derived from post-source decay. The latter ions are particularly abundant from carbohydrates containing sialic acids as the

David J Harvey; Ann P Hunter; Robert H Bateman; Jeff Brown; Glen Critchley

1999-01-01

412

Characterisation of product ions in high-energy tandem mass spectra of protonated oligonucleotides formed by electrospray ionisation 3 3 Dedicated to Professor J. Morrison on the occasion of his 75th birthday in recognition of his distinguished contributions to mass spectrometry  

Microsoft Academic Search

Tandem mass spectra of positively charged ions of a range of small oligonucleotides (6–10 mers) have been examined in detail using a hybrid magnetic sector time-of-flight mass spectrometer. This has a higher range of collision energies (up to Elab400 eV) and a different timescale of dissociation compared to triple quadrupole and quadrupole ion trap instruments. Under these conditions loss of

Allan Weimann; Paula Iannitti-Tito; Margaret M Sheil

2000-01-01

413

Assessment of gamma radiolytic degradation in waste lubricating oil by GC/MS and UV/VIS  

NASA Astrophysics Data System (ADS)

The hydrocarbons degradation by gamma irradiation of the waste automotive lubricating oil at different absorbed doses has was investigated. The waste automotive oil in a Brazilian oil recycling company was collected. This sample was fractioned and 50% and 70% (v/v) Milli-Q water were added. Each sample was irradiated with 100, 200 and 500 kGy doses using a gamma source Co-60—GAMMACELL type, with 5×10 3 Ci total activity. Gas chromatography-mass spectrometry (GC/MS) was used to identify degraded organic compounds. The mass spectra were analyzed using the mass spectral library from NIST, installed in the spectrometer. The sample irradiated at 500 kGy dose with 70% (v/v) Milli-Q water addition formed eight degradation products, namely diethanolmethylamine (C 5H 13NO), diethyldiethylene glycol (C 8H 18O 3), 1-octyn-3-ol, 4-ethyl (C 10H 18O) and 1.4-pentanediamine, N1, N1-diethyl (C 9H 22N 2). The color changing of the waste lubricating oil, for different absorbed doses, was determined by UV/VIS spectrophotometer. The related sample showed the lowest absorbance value evidencing the formation of 2-ethoxyethyl ether (C 8H 18O 3) compound.

Scapin, Marcos A.; Duarte, Celina L.; Bustillos, José Oscar W. V.; Sato, Ivone M.

2009-07-01

414

Cosmic Ray Spectra in Nambu-Goldstone Dark Matter Models  

E-print Network

We discuss the cosmic ray spectra in annihilating/decaying Nambu-Goldstone dark matter models. The recent observed positron/electron excesses at PAMELA and Fermi experiments are well fitted by the dark matter with a mass of 3TeV for the annihilating model, while with a mass of 6 TeV for the decaying model. We also show that the Nambu-Goldstone dark matter models predict a distinctive gamma-ray spectrum in a certain parameter space.

Masahiro Ibe; Hitoshi Murayama; Satoshi Shirai; Tsutomu T. Yanagida

2009-08-25

415

A? STRUCTURES ON SOME SPECTRA RELATED TO MORAVA K THEORIES  

Microsoft Academic Search

. Let p denote an odd prime. We show that the spectrum [ E(n), the In -adic completion ofJohnson and Wilson's E(n), admits a unique topological A1 structure compatible with its canonicalring spectrum structure. Furthermore, the canonical morphism of ring spectra [ E(n) \\\\Gamma! K(n) admitsan A1 structure whichever of the uncountably many A1 structures of A. Robinson is imposed

ANDREW BAKER

1991-01-01

416

Combustion diagnostics by laser spectrometry  

NASA Astrophysics Data System (ADS)

We have developed three different types of visualization methods for energy conversion systems by means of laser spectrometry. (1) Laser-induced fluorescence (LIF) spectroscopy and (2) laser ionization mass spectrometry (LIMS) have been applied to visualization of chemical species in combustion fields of flames. (3) Near-infrared laser absorption spectroscopy has been used for visualization of water in a polymer electrolyte fuel cell (PEFC). Complex physicochemical processes in the energy conversion systems have been revealed by laser spectrometry.

Kitagawa, Kuniyuki; Morita, Shigeaki; Kodama, Kenji; Matsumoto, Kozo

2009-03-01

417

Time-of-flight secondary ion mass spectrometry with transmission of energetic primary cluster ions through foil targets  

NASA Astrophysics Data System (ADS)

We developed time-of-flight (TOF) secondary ion (SI) mass spectrometry that provides informative SI ion mass spectra without needing a sophisticated ion beam pulsing system. In the newly developed spectrometry, energetic large cluster ions with energies of the order of sub MeV or greater are used as primary ions. Because their impacts on the target surface produce high yields of SIs, the resulting SI mass spectra are informative. In addition, the start signals necessary for timing information on primary ion incidence are provided by the detection signals of particles emitted from the rear surface of foil targets upon transmission of the primary ions. This configuration allows us to obtain positive and negative TOF SI mass spectra without pulsing system, which requires precise control of the primary ions to give the spectra with good mass resolution. We also successfully applied the TOF SI mass spectrometry with energetic cluster ion impacts to the chemical structure characterization of organic thin film targets.

Hirata, K.; Saitoh, Y.; Chiba, A.; Yamada, K.; Matoba, S.; Narumi, K.

2014-03-01

418

Multi-Epoch Multiwavelength Spectra and Models for Blazar 3C 279  

NASA Technical Reports Server (NTRS)

Of the blazars detected by EGRET in GeV gamma-rays, 3C 279 is not only the best-observed by EGRET, but also one of the best-monitored at lower frequencies. We have assembled eleven spectra, from GHz radio through GeV gamma-rays, from the time intervals of EGRET observations. Although some of the data have appeared in previous publications, most are new, including data taken during the high states in early 1999 and early 2000. All of the spectra show substantial gamma-ray contribution to the total luminosity of the object; in a high state, the gamma-ray luminosity dominates over that at all other frequencies by a factor of more than 10. There is no clear pattern of time correlation; different bands do not always rise and fall together, even in the optical, X-ray, and gamma-ray bands. The spectra are modeled using a leptonic jet, with combined synchrotron self-Compton + external Compton gamma-ray production. Spectral variability of 3C 279 is consistent with variations of the bulk Lorentz factor of the jet, accompanied by changes in the spectral shape of the electron distribution. Our modeling results are consistent with the UV spectrum of 3C 279 being dominated by accretion disk radiation during times of low gamma-ray intensity.

Hartman, R. C.; Boettcher, M.; Aldering, G.; Aller, H.; Aller, M.; Backman, D. E.; Balonek, T. J.; Bertsch, D. L.; Bloom, S. D.; Bock, H.; White, Nicholas E. (Technical Monitor)

2001-01-01

419

Multiparameter liquid scintillation spectrometry  

Microsoft Academic Search

Multiparameter analog to digital conversion and multichannel pulse height analyses, enabling simultaneous acquisition of four different 1024 ch energy spectra, enhance the accuracy of low-level counting of 3H and 14C. The new LS spectrometer, the QUANTULUS, is based on the concept of ``total optimisation'' where all known factors enabling reduction of background and data validation have been considered. These involve:

Henry Polach; Hannu Kojola; Jarmo Nurmi; Erkki Soini

1984-01-01

420

Unthermalized positrons in gamma ray burst sources  

NASA Technical Reports Server (NTRS)

The spectra of the broadening 0.511 MeV annihilation line produced by high temperatures was calculated in the case of unthermalized plasma; i.e., T sub e(+) is not = T sub e(-). The flattening in the spectrum of the annihilation lines for large differences of electron and positron temperatures is a strong indication that the observed features of the hard tailed spectrum of the gamma bursts can be well described by annihilation of unthermalized positrons. It is proposed that the charge separation occurring in Eddington limited accretion onto a neutron star or the one photon pair production in strong magnetic fields as a mechanism for the production of unthermalized positrons in the sources of gamma bursts. From the best fit of experimental spectra by the model, the parameters of sources for which the regions with different plasma temperatures can exist is evaluated.

Tkaczyk, W.; Karakula, S.

1992-01-01

421

Positron annihilation spectra and core-electron enhancement factors  

E-print Network

$\\gamma$-spectra for positron annihilation with core and valence electrons in the noble gases are calculated using many-body theory (MBT). We show that proper inclusion of core annihilation is crucial to accurately describe the measured spectra [Phys. Rev. Lett. 79, 39 (1997)]. We use the MBT to calculate `exact' enhancement factors $\\bar{\\gamma}_{n\\ell}$ for annihilation on individual $n\\ell$ subshells. They parameterize the important effects of (non-local) short-range electron-positron correlations, including the non-perturbative process of virtual positronium formation. We show that they follow a simple and physically motivated scaling with the subshell ionization energy $I_{n\\ell}$: $\\bar{\\gamma}_{n\\ell}=1+\\sqrt{A/I_{n\\ell}}+(B/I_{n\\ell})^{\\beta}$, where $A$, $B$ and $\\beta$ are positive constants. We suggest that this formula can be used with relatively simple independent-particle-approximation calculations to determine accurate core-annihilation spectra for atoms across the periodic table and in condens...

Green, D G

2014-01-01

422

Gamma-ray albedo of the moon  

E-print Network

We use the GEANT4 Monte Carlo framework to calculate the gamma-ray albedo of the Moon due to interactions of cosmic ray (CR) nuclei with moon rock. Our calculation of the albedo spectrum agrees with the EGRET data. We show that the spectrum of gamma rays from the Moon is very steep with an effective cutoff around 4 GeV (600 MeV for the inner part of the Moon disc). Apart from other astrophysical sources, the albedo spectrum of the Moon is well understood, including its absolute normalisation; this makes it a useful "standard candle" for gamma-ray telescopes, such as the forthcoming Gamma Ray Large Area Space Telescope (GLAST). The albedo flux depends on the incident CR spectrum which changes over the solar cycle. Therefore, it is possible to monitor the CR spectrum using the albedo gamma-ray flux. Simultaneous measurements of CR proton and helium spectra by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA), and observations of the albedo gamma rays by the GLAST Large Area Telescope (LAT), can be used to test the model predictions and will enable the GLAST LAT to monitor the CR spectrum near the Earth beyond the lifetime of PAMELA.

Igor V. Moskalenko; Troy A. Porter

2007-05-25

423

Mass Spectrometry of Glycans  

PubMed Central

Powerful new strategies based on mass spectrometry are revolutionizing the structural analysis and profiling of glycans and glycoconjugates. We survey here the major biosynthetic pathways that underlie the biological diversity in glycobiology, with emphasis on glycoproteins, and the approaches that can be used to address the resulting heterogeneity. Included among these are derivatizations, on- and off-line chromatography, electrospray and matrix-assisted laser desorption/ionization, and a variety of dissociation methods, the recently introduced electron-based techniques being of particular interest. PMID:24010834

Han, Liang; Costello, Catherine E.

2014-01-01

424

Quantitative biomedical mass spectrometry  

NASA Astrophysics Data System (ADS)

The scope of this contribution is an illustration of the capabilities of isotope dilution mass spectrometry (IDMS) for quantification of target substances in the biomedical field. After a brief discussion of the general principles of quantitative MS in biological samples, special attention will be paid to new technological developments or trends in IDMS from selected examples from the literature. The final section will deal with the use of IDMS for accuracy assessment in clinical chemistry. Methodological aspects considered crucial for avoiding sources of error will be discussed.

de Leenheer, Andrép; Thienpont, Linda M.

1992-09-01

425

Continuum Fitting HST QSO Spectra  

NASA Technical Reports Server (NTRS)

The Principal Component Analysis (PCA) method which we are using to fit and describe QSO spectra relies upon the fact that QSO continuum are generally very smooth and simple except for emission and absorption lines. To see this we need high signal-to-noise (S/N) spectra of QSOs at low redshift which have relatively few absorption lines in the Lyman-a forest. We need a large number of such spectra to use as the basis set for the PCA analysis which will find the set of principal component spectra which describe the QSO family as a whole. We have found that too few HST spectra have the required S/N and hence we need to supplement them with ground based spectra of QSOs at higher redshift. We have many such spectra and we have been working to make them suitable for this analysis. We have concentrated on this topic since 12/15/01.

Tytler, David; Oliversen, Ronald J. (Technical Monitor)

2002-01-01

426

Simultaneous analysis of butene isomer mixtures using process mass spectrometry.  

PubMed

The feasibility of simultaneous analysis of mixtures containing two to four butene isomers and up to six total components using process mass spectrometry is assessed. As for typical (nonisomeric) applications of process mass spectrometry, simultaneous analysis is based on the assumption that the electron ionization mass spectra of mixtures are linear combinations of the spectra of the individual constituents. Limits of detection for binary isomer mixtures are on the order of 0.1% to 10%, limited by the ability to distinguish small differences between similar spectra. As spectral and mixture complexity increase, both accuracy and precision decrease. Not surprisingly the similarity of the spectra of stereoisomers cis- and trans-2-butene is greater than that of the other (nonstereoisomeric) isomer pairs, and mixtures containing both cis- and trans-2-butene are the most difficult to quantitate. However, even for mixtures of all four butenes, accuracy (root-mean-square error = 2.43%), precision (average coefficient of variation = 6.72%), and linearity (correlation coefficient of a plot of measured versus actual concentration r2 = 0.985 +/- 0.002) are reasonably good. PMID:11118115

Bennett, K H; Cook, K D; Seebach, G L

2000-12-01

427

Afterglows as Diagnostics of Gamma Ray Burst Beaming  

E-print Network

If gamma ray bursts are highly collimated, radiating into only a small fraction of the sky, the energy requirements of each event may be reduced by several (up to 4 - 6) orders of magnitude, and the event rate increased correspondingly. The large Lorentz factors (Gamma > 100) inferred from GRB spectra imply relativistic beaming of the gamma rays into an angle 1/Gamma. We are at present ignorant of whether there are ejecta outside this narrow cone. Afterglows allow empirical tests of whether GRBs are well-collimated jets or spherical fireballs. The bulk Lorentz factor decreases and radiation is beamed into an ever increasing solid angle as the burst remnant expands. It follows that if gamma ray bursts are highly collimated, many more optical and radio transients should be observed without associated gamma rays than with them. In addition, a burst whose ejecta are beamed into angle zeta undergoes a qualitative change in evolution when Gamma < 1/zeta: Before this, Gamma ~ r^{-3/2}, while afterwards, Gamma decays exponentially with r. This change results in a potentially observable break in the afterglow light curve. Successful application of either test would eliminate the largest remaining uncertainty in the energy requirements and space density of gamma ray bursters.

James E. Rhoads

1997-12-03

428

Gamma rays from the Crab and Vela pulsars  

NASA Technical Reports Server (NTRS)

Gamma ray pulsed emission from the Crab and Vela pulsars are discussed. Emphasis is placed on use of current and future Gamma Ray Observatory observations as diagnostics to examine and constrain theoretical models. Issues on the spectra and pulse profile are discussed. Specifically, the absence and possibly significant time variability of pulsed emission below 10 MeV from the Vela pulsar represents a serious challenge to current astronomical models. Theoretical implication of this 'peculiarity' is addressed.

Ho, Cheng

1992-01-01

429

A systematic nomenclature for carbohydrate fragmentations in FAB-MS\\/MS spectra of glycoconjugates  

Microsoft Academic Search

A summary of the ion types observed in the Fast Atom Bombardment Mass Spectrometry (FAB-MS) and collision induced decomposition (CID) MS\\/MS spectra of glycoconjugates (glycosphingolipids, glycopeptides, glycosides and carbohydrates) is presented. The variety of product ion types that arise by cleavages within the carbohydrate moieties has prompted us to introduce a systematic nomenclature to designate these ions. The proposed nomenclature

Bruno Domon; Catherine E Costello

1988-01-01

430

Multispectra CWT-Based Algorithm (MCWT) in Mass Spectra for Peak Extraction  

Microsoft Academic Search

An important objective in mass spectrometry (MS) is to identify a set of biomarkers that can be used to potentially distinguish patients between distinct treatments (or conditions) from tens or hundreds of spectra. A common two-step approach involving peak extraction and quantification is employed to identify the features of scientific interest. The selected features are then used for further investigation

Huey-Miin Hsueh; Hsun-chih Kuo; Chen-An Tsai

2008-01-01

431

Identification of Differentially Expressed Proteins Using MALDI-TOF Mass Spectra  

E-print Network

and therapeutic strategies for lung cancer, matrix-assisted laser desorption/ionization time- of-flight mass Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry hasIdentification of Differentially Expressed Proteins Using MALDI-TOF Mass Spectra Qiuhua Liu,1

Hartemink, Alexander

432

A scale space approach for unsupervised feature selection in mass spectra classification for ovarian cancer detection  

Microsoft Academic Search

BACKGROUND: Mass spectrometry spectra, widely used in proteomics studies as a screening tool for protein profiling and to detect discriminatory signals, are high dimensional data. A large number of local maxima (a.k.a. peaks) have to be analyzed as part of computational pipelines aimed at the realization of efficient predictive and screening protocols. With this kind of data dimensions and samples

Michele Ceccarelli; Antonio d'Acierno; Angelo Facchiano

2009-01-01

433

Determination of vibration-rotation lines intensities from absorption Fourier spectra  

NASA Technical Reports Server (NTRS)

The method presented allows the line intensities to be calculated from either their equivalent widths, heights, or quantities deduced from spectra obtained by Fourier spectrometry. This method has proven its effectiveness in measuring intensities of 60 lines of the molecule H2O with a precision of 10%. However, this method cannot be applied to isolated lines.

Mandin, J. Y.

1979-01-01

434

Analysis of Proteomic Mass Spectra Based on Multivariate Feature Fusion Visualization  

Microsoft Academic Search

Protein mass spectrometry (MS) pattern recognition has recently emerged as a new method for cancer diagnosis. Application of proteomic mass spectra coupled with pattern classification techniques to discover novel biomarkers has been successfully used for the predictive diagnoses of several cancer diseases. However, the extraction of good features that can represent the identities of different classes plays the frontal critical

Hui Meng; Wenxue Hong; Jialin Song; Liqiang Wang

2008-01-01

435

A chemometric study on human breath mass spectra for biomarker identification in cystic fibrosis  

Microsoft Academic Search

Alveolar breath samples from a small case-control study population have been collected and measured via ion-molecule reaction mass spectrometry, and a constructive statistical approach to the identification of volatile biomarkers has been formulated by applying multivariate statistical methods on the mass spectra. The nature of the data is such that the number of variables largely exceeds the observations, representing a

L. Bennett; L. Ciaffoni; W. Denzer; G. Hancock; A. D. Lunn; R. Peverall; S. Praun; G. A. D. Ritchie

2009-01-01

436

Differential mobility spectrometry-driven shotgun lipidomics.  

PubMed

The analysis of lipids by mass spectrometry (MS) can provide in-depth characterization for many forms of biological samples. However, such workflows can also be hampered by challenges like low chromatographic resolution for lipid separations and the convolution of mass spectra from isomeric and isobaric species. To address these issues, we describe the use of differential mobility spectrometry (DMS) as a rapid and predictable separation technique within a shotgun lipidomics workflow, with a special focus on phospholipids (PLs). These analytes, ionized by electrospray ionization (ESI), are filtered using DMS prior to MS analysis. The observed separation (measured in terms of DMS compensation voltage) is affected by several factors, including the m/z of the lipid ion, the structure of an individual ion, and the presence of chemical modifiers in the DMS cell. Such DMS separations can simplify the analysis of complex extracts in a robust and reproducible manner, independent of utilized MS instrumentation. The predictable separation achieved with DMS can facilitate correct lipid assignments among many isobaric and isomeric species independent of the resolution settings of the MS analysis. This leads to highly comprehensive and quantitative lipidomic outputs through rapid profiling analyses, such as Q1 and MRM scans. The ultimate benefit of the DMS separation in this unique shotgun lipidomics workflow is its ability to separate many isobaric and isomeric lipids that by standard shotgun lipidomics workflows are difficult to assess precisely, for example, ether and diacyl species and phosphatidylcholine (PC) and sphingomyelin (SM) lipids. PMID:25160652

Lintonen, Tuulia P I; Baker, Paul R S; Suoniemi, Matti; Ubhi, Baljit K; Koistinen, Kaisa M; Duchoslav, Eva; Campbell, J Larry; Ekroos, Kim

2014-10-01

437

Mass Spectrometry of Proteins in Liquids  

NASA Astrophysics Data System (ADS)

Infrared matrix assisted laser desorption/ionization mass spectrometry (IR-MALDI) is an effective technique for mass identification and structural analysis of biomolecules. We are using liquid glycerol/water matrices in a reflectron time-of-flight mass spectrometer equipped with a liquid nitrogen cooled sample stage to provide a more natural environment for biomolecules. An Er:YAG laser (2.94 ?m) and also a tunable free electron laser (2-9 ?m) are used to induce desorption and ionization by exciting the O-H and CH2 stretching vibrations in the glycerol. This vibrationally enhanced ionization makes IR-MALDI very efficient, as observed in the mass spectra of small peptides. This work is a first step toward using mass spectrometry to study noncovalently bound protein complexes in vitro and to study proteins in their cellular environment. Supported by the Medical Free Electron Laser Program of the Office of Naval Research and the Vanderbilt Molecular Biophysics Training Grant of the National Institutes of Health

Baltz-Knorr, Michelle; Papantonakis, Michael; Ermer Haglund, David, Jr.

1999-11-01

438

Measurement of ²²?Ra in soil from oil field: advantages of ?-ray spectrometry and application to the IAEA-448 CRM.  

PubMed

The analytical performance of gamma-ray spectrometry for the measurement of (226)Ra in TENORM (Technically Enhanced Naturally Occurring Radioactive Material) soil was investigated by the IAEA. Fast results were obtained for characterization and certification of a new TENORM Certified Reference Material (CRM), identified as IAEA-448 (soil from oil field). The combined standard uncertainty of the gamma-ray spectrometry results is of the order of 2-3% for massic activity measurement values ranging from 16500 Bq kg(-1) to 21500 Bq kg(-1). Methodologies used for the production and certification of the IAEA-448 CRM are presented. Analytical results were confirmed by alpha spectrometry. The "t" test showed agreement between alpha and gamma results at 95% confidence level. PMID:24332337

Ceccatelli, A; Katona, R; Kis-Benedek, G; Pitois, A

2014-05-01

439

Isotope Ratio Mass Spectrometry.  

PubMed

Isotope Ratio Mass Spectrometry (IRMS) is a specialized technique used to provide information about the geographic, chemical, and biological origins of substances. The ability to determine the source of an organic substance stems from the relative isotopic abundances of the elements which comprise the material. Because the isotope ratios of elements such as carbon, hydrogen, oxygen, sulfur, and nitrogen can become locally enriched or depleted through a variety of kinetic and thermodynamic factors, measurement of the isotope ratios can be used to differentiate between samples which otherwise share identical chemical compositions. Several sample introduction methods are now available for commercial isotope ratio mass spectrometers. Combustion is most commonly used for bulk isotopic analysis, whereas gas and liquid chromatography are predominately used for the real-time isotopic analysis of specific compounds within a mixture. Here, highlights of advances in instrumentation and applications within the last three years are provided to illustrate the impact of this rapidly growing area of research. Some prominent new applications include authenticating organic food produce, ascertaining whether or not African elephants are guilty of night-time raids on farmers' crops, and linking forensic drug and soil samples from a crime scene to a suspected point of origin. For the sake of brevity, we focus this Minireview on the isotope ratio measurements of lighter-elements common to organic sources; we do not cover the equally important field of inorganic isotope ratio mass spectrometry. PMID:19173039

Muccio, Zeland; Jackson, Glen P

2009-02-01

440

Mass Spectrometry Video  

NSDL National Science Digital Library

This video, distributed on YouTube by the Royal Society of Chemistry is on the basic principles of mass spectrometry, using a magnetic sector instrument to demonstrate how specific m/z ratios can be selected. The theory and operation of MS, including the chemistry of ionization and fragmentation is described at an introductory level. There is also an excellent example of the use of high resolution MS to differentiate between nominal mass and actual mass. The video does a very good job of explaining the concept such that only a little background knowledge is required. The video is short enough (6 mins), that it would be very useful in a class setting or for students outside of class. The ultimate strength of this video is the general nature of the content that makes it appealing to a wide audience. The video may be most appropriate in a lower-level general education science course (i.e forensic science) or as a quick orientation video for instrumental analysis students prior to introducing mathematical or operational concepts. This video would also be helpful for a lay science person who wishes to learn more about mass spectrometry from a general interest perspective.

2011-06-08

441

Toward understanding the ionization of biomarkers from micrometer particles by bio-aerosol mass spectrometry  

Microsoft Academic Search

The appearance of informative signals in the mass spectra of laser-ablated bio-aerosol particles depends on the effective\\u000a ionization probabilities (EIP) of individual components during the laser ionization process. This study investigates how bio-aerosol\\u000a chemical composition governs the EIP values of specific components and the overall features of the spectra from the bio-aerosol\\u000a mass spectrometry (BAMS). EIP values were determined for

Scott C. Russell; Gregg Czerwieniec; Carlito Lebrilla; Herbert Tobias; David P. Fergenson; Paul Steele; Maurice Pitesky; Joanne Horn; Abneesh Srivastava; Matthias Frank; Eric E. Gard

2004-01-01

442

Gamma-rigid solution of the Bohr Hamiltonian for gamma = 30 degrees compared to the E(5) critical point symmetry  

E-print Network

A gamma-rigid solution of the Bohr Hamiltonian for gamma = 30 degrees is derived, its ground state band being related to the second order Casimir operator of the Euclidean algebra E(4). Parameter-free (up to overall scale factors) predictions for spectra and B(E2) transition rates are in close agreement to the E(5) critical point symmetry, as well as to experimental data in the Xe region around A=130.

Dennis Bonatsos; D. Lenis; D. Petrellis; P. A. Terziev; I. Yigitoglu

2005-07-08

443

Gamma rays interaction with copper doped lithium phosphate glasses  

NASA Astrophysics Data System (ADS)

Undoped and copper-doped lithium phosphate glasses were prepared. CuO-doped glasses possess characteristic greenish color which deepens with the increase of CuO content. Experimental optical absorption spectra of the undoped lithium phosphate glasses reveal strong ultraviolet absorption bands and no visible bands are observed. These strong UV bands are assumed to originate from unavoidable trace iron ions contamination within the chemicals used for the preparation of the glass. The optical absorption spectra of the CuO-doped phosphate glasses reveal the same UV absorption as observed in the undoped samples beside an extra broad visible absorption band which splits to some component peaks. Such visible spectra are related to the presence of divalent copper (Cu2+) ions in distorted octahedral coordination. Gamma irradiation of the undoped sample produces induced defects generated through the liberation of pairs of electrons and positive holes. CuO-doped glasses show some shielding behavior towards successive gamma irradiation especially at high CuO contents. FTIR absorption spectra of the studied glasses indicate the appearance of characteristic vibrational bands due to phosphate groups. Gamma irradiation causes minor effects on the FTIR spectra, but the bands due to water molecules are strongly affected by gamma irradiation because of loose bonding within the glass network.

ElBatal, Hatem A.; ElMandouh, Zeinab E.; Zayed, Hamdia A.; Marzouk, Samir Y.; Elkomy, Gihan M.; Hosny, Ahmed

2013-12-01

444

Gamma-Gamma Physics at LEP2  

E-print Network

This report is an overview of the gamma-gamma physics capabilities of LEP2, and covers the following topics: structure functions, equivalent photon approximation, tagging conditions etc, soft and semihard physics, large-$p_t$ processes, heavy-quark physics, and exclusive channels.

P. Aurenche; G. A. Schuler; A. Bawa; E. Boudinov; A. Buijs; M. Cacciari; A. Corsetti; W. Da Silva; M. Dubinin; R. Engel; F. Erne; J. Field; A. Finch; J. Forshaw; R. Godbole; J. Ph. Guillet; S. R. Hou; F. Kapusta; B. Kennedy; M. N. Kienzle; M. Kraemer; P. Kroll; E. Laenen; M. Lehto; L. Lonnblad; D. Miller; G. Pancheri; J. Parisi; D. Perret-Gallix; J. Ranft; T. van Rhee; S. Riemersma; V. Serbo; M. H. Seymour; Y. Shimizu; T. Sjostrand; S. Soldner-Rembold; M. Stratmann; I. Tyapkin; A. Vogt; J. Ward; B. Wilkens; A. Wright; N. I. Zimin

1996-01-23

445

Degradation pathways of PCB upon gamma irradiation  

SciTech Connect

In order to understand the modifications of the chromatographic profile of Aroclor 1260 upon gamma irradiation, a total of 14 pure polychlorinated biphenyl (PCB) congeners were separately irradiated in solution. Dechlorination was observed, and the generated products were investigated by gas chromatography and mass spectrometry. Degradation proceeds more rapidly in methanol/water mixture than in petroleum ether, but the relative amount of ortho-dechlorinated congeners formed upon irradiation was smaller in the former solvent Ortho chlorines are preferentially lost in petroleum ether except when they are involved in a 2,5 (or 3,6) substitution pattern, in which case para dechlorination becomes predominant. The precursors of some toxicologically important congeners such as congeners 77, 118, 167, and 189 have been identified. These data are useful to rationalize the modifications of the chromatographic profile of PCB complex mixture upon gamma irradiation.

Lepine, F. (Institut Armand-Frappier, Laval, Quebec (Canada)); Masse, R. (Institut National de la Recherche Scientifique, Pointe-Claire, Quebec (Canada))

1990-11-01

446

Novel beta-gamma coincidence measurements using phoswich detectors  

Microsoft Academic Search

Summary  We have developed an analysis pipeline for air filter gamma-ray spectra, utilizing the software packages UniSampo for peak analysis and Shaman for nuclide identification. In an automated usage mode, spectra that are received via e-mail are processed into a directory tree, analyzed with UniSampo and Shaman, and finally categorized on the basis of the analysis results. Alarms are generated if

James H. Ely; Craig E. Aalseth; Justin I. McIntyre

2005-01-01

447

Cosmology from quasar spectra  

NASA Astrophysics Data System (ADS)

High resolution spectroscopy of high redshift quasar spectra enables us to investigate the properties of the intergalactic medium (IGM) and measure cosmological parameters from the Lya forest. Toward high precision cosmology, this dissertation presents the following four topics. (1) Principal Component Analysis (PCA) on quasar spectrum: We introduce the PCA to describe quasar emission lines and continua quantitatively, and we attempt to make a prediction of the continuum shape in the Lya forest using wavelengths redward of Lya emission. (2) Flux calibration of Keck HIRES data: On our way to achieve high accuracy measurement, it was necessary to develop new calibration schemes and explore the origin of systematic errors. My contribution includes the following and is discussed throughout the thesis: (i) the development of the flux calibration scheme, (ii) the discovery of three emission lines in the Lya forest, (iii) the establishment of high resolution standard star spectra, and (iv) the identification of ozone lines in the spectrum. (3) D/H measurement: We present precise measurements of the primordial deuterium to hydrogen ratio (D/ H) toward two quasars, HS0105+1619 and Q1243+3047, which constrains the baryon to photon ratio e = 5.9 +/- 0.5 x 10 -10 or the baryon density O b h 2 = 0.0214 +/- 0.0020 via the Big Bang Nucleosynthesis theory. (4) Studies of the Lya forest at z ~ 2: We also present the measurements of the total amount of neutral hydrogen absorption in the IGM. We compare our observed data with hydrodynamic simulations and find good agreement when we use the following cosmological parameters: H o = 71 kin s -1 Mpc -1 , O L = 0.73, O m = 0.27, O b = 0.044, the amplitude of the power spectrum s 8 = 0.9, and the photoinization rate G 912 = (1.44 +/- 0.11) x 10 -12 s -1 . We conclude that the measurements of the cosmological parameters from our primordial D/H measurements, recent WMAP satellite observation of the cosmic microwave background, and our the total amount of neutral hydrogen in the IGM at z ~ 2 are in a concordance with the LCDM model.

Suzuki, Nao

2005-11-01

448

Isotope dilution mass spectrometry  

NASA Astrophysics Data System (ADS)

In the past isotope dilution mass spectrometry (IDMS) has usually been applied using the formation of positive thermal ions of metals. Especially in calibrating other analytical methods and for the certification of standard reference materials this type of IDMS became a routine method. Today, the progress in this field lies in the determination of ultra trace amounts of elements, e.g. of heavy metals in Antarctic ice and in aerosols in remote areas down to the sub-pg g-1 and sub-pg m-3 levels respectively, in the analysis of uranium and thorium at concentrations of a few pg g-1 in sputter targets for the production of micro- electronic devices or in the determination of sub-picogram amounts of230Th in corals for geochemical age determinations and of226Ra in rock samples. During the last few years negative thermal ionization IDMS has become a f