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1

Automatic analysis of Rutherford backscattering spectrometry spectra  

Microsoft Academic Search

It has been shown that Bayesian statistics is a powerful tool in the analysis of ion beam analysis (IBA) data. Past work has shown its applicability to the deconvolution of the detector response function from micro-Rutherford backscattering spectrometry (RBS) and micro-proton-induced X-ray emission (PIXE) spectra, subtraction of the background from PIXE spectra, the extraction of depth profiles from PIXE spectra

J. Padayachee; K. A. Meyer; V. M. Prozesky

2001-01-01

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

Continuous Energy gamma-Ray Spectrometry.  

National Technical Information Service (NTIS)

Compton recoil gamma-ray spectroscopy provides absolute measurements of continuous gamma-ray spectra. Peaks which possess sufficient intensity above the continuum level can be observed. Since the inception of this spectrometric method, this method has evo...

R. Gold B. J. Kaiser J. P. McNeece

1983-01-01

4

Low-level gamma-ray spectrometry  

SciTech Connect

Low-level gamma-ray spectrometry generally equates to high-sensitivity gamma-ray spectrometry that can be attained by background reduction, selective signal identification, or some combination of both. Various methods for selectively identifying gamma-ray events and for reducing the background in gamma-ray spectrometers are given. The relative magnitude of each effect on overall sensitivity and the relative cost'' for implementing them are given so that a cost/benefit comparison can be made and a sufficiently sensitive spectrometer system can be designed for any application without going to excessive or unnecessary expense. 10 refs., 8 figs.

Brodzinski, R.L.

1990-10-01

5

GAMANAL. Interpretation of Gamma-Ray Spectra  

Microsoft Academic Search

GAMANAL provides a complete qualitative and quantitative analysis of mixtures of radioactive species such as fission products by computer interpretation of high-resolution gamma-ray spectra. The program first determines and removes the background or Compton continuum under the peaks in a spectrum to locate the peak regions. This is done by examining the pulse-height spectrum data for background and peak regions

Gunnink

1986-01-01

6

Janus probe, a detection system for high energy reactor gamma-ray spectrometry  

SciTech Connect

In reactor environments, gamma-ray spectra are continuous and the absolute magnitude as well as the general shape of the gamma continuum are of paramount importance. Consequently, conventional methods of gamma-ray detection are not suitable for in-core gamma-ray spectrometry. To meet these specific needs, a method of continuous gamma-ray spectrometry, namely Compton Recoil Gamma-Ray Spectrometry, was developed for in-situ observations of reactor environments. A new gamma-ray detection system has been developed which extends the applicability of Compton Recoil Gamma-Ray Spectrometry up to roughly 7 MeV. This detection system is comprised of two separate Si(Li) detectors placed face-to-face. Hence this new detection system is called the Janus probe. Also shown is the block diagram of pulse processing instrumentation for the Janus probe. This new gamma probe not only extends the upper energy limit of in-core gamma-ray spectrometry, but in addition possesses other fundamental advantages.

Gold, R.; Kaiser, B.J.

1980-03-01

7

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

8

Covariance analysis of gamma ray spectra.  

PubMed

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. PMID:23387645

Trainham, R; Tinsley, J

2013-01-01

9

Covariance analysis of gamma ray spectra  

NASA Astrophysics Data System (ADS)

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

10

Gamma spectra and nuclide identification catalog. 2nd edition  

Microsoft Academic Search

This catalog contains an abbreviated listing of nuclides, gamma rays, and spectra frequently encountered in radiation measurements. Only the most prominent gamma rays for each nuclide are given. Part I is a nuclide index. Part II is intended for use in identifying nuclides from gamma energies observed in spectrum. Part III consists of examples of scintillation spectra. (RWR)

G. Gleason; B. H. Reed

1979-01-01

11

Parametric Studies for 233U Gamma Spectrometry  

SciTech Connect

Quantification of special nuclear material is a necessary aspect to assuring material accountability and is often accomplished using non-destructive gamma spectrometry. For 233U, gamma rays are affected by matrix and packaging attenuation and by a strong Compton continuum from decay products of 232U (inherently found in 233U) that obscure 233U gamma photopeaks. This project, based on current work at the national repository for separated 233U located at Oak Ridge National Laboratory (ORNL), explores the effects of various parameters on the quantification of 233U– including material form and geometry. Using an attenuation correction methodology for calculating the mass of 233U from NDA analysis, a bias of almost 75% less than the actual 233U mass was identified. The source of the bias needs to be understood at a more fundamental level for further use of this quantification method. Therefore, controlled experiments using well characterized packages of 233U were conducted at the repository and are presented in this paper.

Scheffing, C.C.; Krichinsky, A.

2004-01-01

12

Natural gamma-ray spectrometry as a tool for radiation dose and radon hazard modelling  

Microsoft Academic Search

We reviewed the calibration procedures of gamma-ray spectrometry with particular emphasis to factors that affect accuracy, detection limits and background radiation in field measurements for dosimetric and radon potential mapping. Gamma-ray spectra were acquired in western Liguria (Italy). The energy windows investigated are centred on the photopeaks of 214Bi (1.76MeV), 208Tl (2.62MeV) and 40K (1.46MeV). The inferred absorbed dose rate

M. Verdoya; P. Chiozzi; P. De Felice; V. Pasquale; M. Bochiolo; I. Genovesi

2009-01-01

13

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

14

Standardisation of Gas Containers Used in gamma Spectrometry.  

National Technical Information Service (NTIS)

The diversity of gamma spectrometry applications brings out the need to standardise the conditioning of samples (gas-liquid, etc ....). Such standardisation leads to better suited and reproducible geometries but also to reduced costs and higher quality ca...

T. Pineira H. Goenvec

1986-01-01

15

Analysis of gamma ray burst spectra with cyclotron lines.  

National Technical Information Service (NTIS)

Motivated by the recent developments in the cyclotron resonance upscattering of soft photons or CUSP model of Gamma Ray Burst (GRB) continuum spectra, we revisit a select database of GRBs with credible cyclotron absorption features. We measure the break e...

V. Kargatis E. P. Liang

1990-01-01

16

Cadium-Zinc-Telluride (CZT) Gamma Ray Spectrometry  

Microsoft Academic Search

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

William Quam

2001-01-01

17

Thunderstorm ground enhancements: Gamma ray differential energy spectra  

NASA Astrophysics Data System (ADS)

The shape and evolution of the energy spectra of the thunderstorm ground enhancement (TGE) electrons and gamma rays shed light on the origin of TGEs, on the relationship of modification of the energy spectra (MOS) and relativistic runaway electron avalanche processes, on the nature of the seed particles, and on the strength and elongation of an atmospheric electric field. However, till now the measurements of energy spectra of TGE electrons and gamma rays have been rather scarce. For the first time, we present differential energy spectra of gamma rays in the wide energy range 4-100 MeV for five TGE events detected in 2012-2013 at Aragats. We use the special technique of electron/gamma ray fraction determination to select TGE events with very small contamination of electrons. The network of large NaI spectrometers located 3200 m above sea level measured energy spectra of gamma rays. The power law indices of “small” TGEs are rather close to the background cosmic gamma ray spectrum (?˜-2); thus, we may deduce that these small events are due to MOS of cosmic ray electrons in the electric field of a thundercloud. Larger TGEs measured by the NaI network and the two largest TGE events earlier recovered from energy releases in a 60-cm-thick scintillator have much steeper energy spectra typical for the avalanche process in atmosphere. The classification of TGEs according to intensity and gamma ray spectral index pointed toward two main mechanisms of the TGE gamma ray origin: the runaway process and modification of electron energy spectra in the thunderstorm atmospheres.

Chilingarian, A.; Hovsepyan, G.; Kozliner, L.

2013-10-01

18

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

19

Efficient Simulation of ESEEM Spectra Using Gamma  

NASA Astrophysics Data System (ADS)

Using the Gamma class library for C++ it is possible to write very efficient time-domain simulation programs for echo-detected pulse EPR experiments, such as three-pulse ESEEM and HYSCORE. By grouping sections of time-invariant propagators, the initial density operator and the detection operator can be re-defined, and the simulation transforms to that of a free induction decay which can be evaluated very efficiently using elements from Gamma. Compared to a straightforward implementation, reductions in computing time of up to a factor of 673 have been found.

Shane, Johan J.; Liesum, Lorenz P.; Schweiger, Arthur

1998-09-01

20

Low-level gamma-ray spectrometry for environmental samples  

Microsoft Academic Search

Low-level gamma-ray spectrometry with large volume HPGe detectors has been widely used in analysis of environmental radionuclides.\\u000a The reasons are excellent energy resolution and high efficiency that permits selective and non-destructive analyses of several\\u000a radionuclides in composite samples. Although the most effective way of increasing the sensitivity of a gamma-ray spectrometer\\u000a is to increase counting efficiency and the amount of

P. P. Povinec

2008-01-01

21

CdWO4 crystal in gamma-ray spectrometry  

Microsoft Academic Search

The properties of CdWO4 (CWO) crystals in gamma spectrometry were studied. Several small samples of 10×10×3 mm size, typically used in CT X-ray detectors, were tested and then compared to the performance of a larger crystal of 20 mm in diameter and 20 mm in height. The light output, energy resolution, and non-proportionality of the CWO response versus gamma-ray energy,

M. Moszynski; M. Balcerzyk; M. Kapusta; A. Syntfeld; D. Wolski; G. Pausch; J. Stein; P. Schotanus

2004-01-01

22

Use of airborne gamma-ray spectrometry for kaolin exploration  

Microsoft Academic Search

Airborne gamma-ray spectrometry was used to define targets with kaolin potential in the Armorican Massif of Brittany, France. This exploration method is based on the principle that kaolinite, an aluminosilicate clay mineral constituting kaolin, is formed by the hydrolysis of potash feldspar with the elimination of potassium. Therefore, potassium contrast between favourable host-rock such as a leucogranite and kaolin occurrence

B. Tourliere; J. Perrin; P Le Berre; J. F Pasquet

2003-01-01

23

Gamma Rays in Spectra Measured by the Kaguya Gamma-Ray Spectrometer  

NASA Astrophysics Data System (ADS)

Of 200 peaks observed in spectra measured by the Kaguya Gamma Ray Spectrometer, the sources of 80% have been identified. Most are from the Ge detector, structural Al, and other local matter. Some gamma rays are from several elements in the Moon.

Reedy, R. C.; Hasebe, N.; Yamashita, N.; Karouji, Y.; Hareyama, M.; Kobayashi, S.; Okudaira, O.; Shibamura, E.; Kobayashi, M. N.; Kim, K. J.; D'Uston, C.; Diez, B.; Gasnault, O.; Forni, O.; Kaguya GRS Team

2009-03-01

24

GAMMA RAY ENERGY SPECTRA FROM THERMAL NEUTRON CAPTURE  

Microsoft Academic Search

Energy spectra of gamma rays resulting from thermal neutron capture are ; compiled for 48 elements. The data are presented in both graphical and tabular ; form. Thermal-neutron-capture cross sections, isotopic abundances, binding ; energies of the extra neutron in the isotopes, and weighted-average binding ; energies are also tabulated. (auth);

Deloume

1958-01-01

25

GAMMA RAY ENERGY SPECTRA FROM THERMAL NEUTRON CAPTURE  

Microsoft Academic Search

Energy spectra of gamma rays resulting from thermal neutron capture are ; compiled for forty-nine elements. The data are presented in both graphical and ; tabular form. Thermal neutron capture cross sections, isotopic abundances, ; binding energies of the extra neutron in the isotopes, and weighted average ; binding energies are also tabulated. (auth);

Deloume

1958-01-01

26

Statistical Theory of Gamma-Ray Spectra Following Nuclear Reactions  

Microsoft Academic Search

A theory predicting gamma-ray spectra following intermediate or high-energy nuclear reactions is derived on the basis of the statistical theory. The equations take a particularly simple form if the assumption is made that all radiative transitions are of the electric dipole type. The theory is applied to two specific reactions: inelastic neutron scattering and thermal neutron capture. Numerical calculations of

E. S. Troubetzkoy

1961-01-01

27

GAMMA AND INTERNAL CONVERSION ELECTRON SPECTRA IN Gd ISOTOPE (n,$gamma$) REACTION  

Microsoft Academic Search

S>A magnetic Compton spectrometer wtth 0.3% resolving power at E\\/sub ; gamma \\/ > 2 Mev and 0.6% at E\\/sub gamma \\/ = 1 Mev was used in an investigation ; of Gd¹⁵⁵ and Gd¹⁵⁷ gamma spectra at 0.4 to 9 Mev, The internal ; conversion electrons at 20 kev to 3 Mev were also studied. The measurements were ;

L. V. Groshev; A. M. Demidov; V. A. Ivanov; V. N. Lutsenko; V. I. Pelekhov

1962-01-01

28

Further development of IDGS: Isotope dilution gamma-ray spectrometry  

SciTech Connect

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% for {sup 239}Pu and {sup 240}Pu isotopic analyses and {approximately}1% for the plutonium concentration analysis. 5 refs., 2 figs., 7 tabs.

Li, T.K.; Parker, J.L. (Los Alamos National Lab., NM (United States)); Kuno, Y.; Sato, S.; Kamata, M.; Akiyama, T. (Power Reactor and Nuclear Fuel Development Corp., Tokai, Ibaraki (Japan))

1991-01-01

29

Inversion of neutron/gamma spectra from scintillator measurements  

NASA Astrophysics Data System (ADS)

The Radiation Assessment Detector (RAD) on-board NASA's Mars Science Laboratory (MSL) rover will measure charged particles as well as neutron and gamma radiation on the Martian surface. Neutral particles are an important contribution to this radiation environment. RAD measures them with a CsI (Tl) and a plastic scintillator, which are both surrounded by an anticoincidence. The incident neutron/gamma spectrum is obtained from the measurements using inversion methods which often fit a functional behavior, e.g., a power law, to the measured data applying the instrument response function and, e.g., a least-squares method. In situations where count rates are small, i.e., where the stochastic nature of the measurement is evident, maximum likelihood estimates with underlying Poissonian statistics improve the resulting spectra. We demonstrate the measurement and inversion of gamma/neutron spectra for a detector concept featuring one high-density scintillator and one high-proton-content scintillator. The applied inversion methods derive the original spectra without any strong assumptions of the functional behavior. Instrument response functions are obtained from Monte-Carlo simulations in matrix form with which the instrument response is treated as a set of linear equations. Using the response matrices we compare a constrained least-squares minimization, a chi-squared minimization and a maximum likelihood method with underlying Poissonian statistics. We make no assumptions about the incident particle spectrum and the methods intrinsically satisfy the constraint of non-negative counts. We analyzed neutron beam measurements made at the Physikalisch Technische Bundesanstalt (PTB) and inverted the measurement data for both neutron and gamma spectra. Monte-Carlo-generated measurements of the expected Martian neutron/gamma spectra were inverted as well, here the maximum likelihood method with underlying Poissonian statistics produces significantly better results.

Köhler, J.; Ehresmann, B.; Martin, C.; Böhm, E.; Kharytonov, A.; Kortmann, O.; Zeitlin, C.; Hassler, D. M.; Wimmer-Schweingruber, R. F.

2011-11-01

30

Gamma-ray spectrometry in light-water-reactor environments  

SciTech Connect

To satisfy the needs of the Light Water Reactor Pressure Vessel Surveillance Dosimetry Improvement Program, differential and integral measurements have been in a light water reactor (LWR) pressure vessel simulator (PVS) at the poolside critical assembly (PAC) in Oak Ridge National Laboratory (ORNL). Within this framework, continuous gamma-ray spectrometry was carried out using Compton recoil gamma-ray spectroscopy. Advances in the state-of-the-art of this method are described with special emphasis given to the capabilities of the new Janus spectrometer. This new Janus spectrometer possessses many advantages and most notably extends the domain of continuous gamma-ray spectrometry up to roughly 6 MeV. Three different configurations of the LWR-PVS in the PCA have been studied.

Gold, R.; Kaiser, B.J.; McNeece, J.P.

1982-02-16

31

Inversion of neutron/gamma spectra from scintillator measurements  

NASA Astrophysics Data System (ADS)

We demonstrate the measurement and inversion of gamma/neutron spectra for a detector concept featuring one high-density scintillator and one high-proton-content scintillator for the example of the Radiation Assessment Detector on-board NASA's Mars Science Laboratory. The applied inversion methods derive the original spectra without any strong assumptions of the functional behavior. Instrument response functions are obtained from Monte-Carlo simulations in matrix form with which the instrument response is treated as a set of linear equations. Using the response matrices we compare a constrained least squares minimization, a chi-squared minimization and a maximum likelihood method with underlying Poissonian statistics. We make no assumptions about the incident particle spectrum and the methods intrinsically satisfy the constraint of non-negative counts. We analyzed neutron beam measurements made at the Physikalisch Technische Bundesanstalt (PTB) and inverted the measurement data for both neutron and gamma spectra. Monte-Carlo-generated measurements of the expected Martian neutron/gamma spectra were inverted as well, here the maximum likelihood method with underlying Poissonian statistics produces significantly better results.

Koehler, J.; Ehresmann, B.; Martin, C.; Böhm, E.; Kharytonov, A.; Kortmann, O.; Zeitlin, C. J.; Hassler, D. M.; Wimmer-Schweingruber, R. F.

2011-12-01

32

A dedicated LIMS for routine gamma-ray spectrometry.  

PubMed

We developed a Microsoft(®) Access-based LIMS (Laboratory Information and Management Systems), ?-LIMS, for the management of our gamma-spectrometry laboratory, in which thousands of routine, but high-quality analyses are performed each year. This paper explains the main features of the ?-LIMS and puts special attention on the interfacing methods and solutions for using the Genie™2000 spectrometry software in conjunction with the EFFTRAN package, which serves for efficiency transfer calculations, coincidence summing corrections and a procedure for uncertainty estimation. PMID:24332338

Bruggeman, M; Verheyen, L; Vidmar, T

2014-05-01

33

Gamma-ray spectrometry of LDEF samples  

SciTech Connect

A total of 31 samples from the Long Duration Exposure Facility (LDEF), including materials of aluminum, vanadium, and steel trunnions were analyzed by ultra-low-level gamma spectroscopy. The study quantified particle induced activations of (sup 22)Na, {sup 46}Sc, {sup 51}Cr, {sup 54}Mn, {sup 56}Co, {sup 57}Co, {sup 58}Co, and {sup 60}Co. The samples of trunnion sections exhibited increasing activity toward the outer end of the trunnion and decreasing activity toward its radial center. The trunnion sections did not include end pieces, which have been reported to collect noticeable {sup 7}Be on their leading surfaces. No significant {sup 7}Be was detected in the samples analyzed. The Underground Counting Facility at Savannah River Laboratory (SRL) was used in this work. The facility is 50 ft. underground, constructed with low-background shielding materials, and operated as a clean room. The most sensitive analyses were performed with a 90%-efficient HPGe gamma-ray detector, which is enclosed in a purged active/passive shield. Each sample was counted for one to six days in two orientations to yield more representative average activities for the sample. The non-standard geometries of the LDEF samples prompted the development of a novel calibration method, whereby the efficiency about the samples surfaces (measured with point sources) predicted the efficiency for the bulk sample.

Winn, W.G.

1991-12-31

34

Gamma-ray spectrometry of LDEF samples  

SciTech Connect

A total of 31 samples from the Long Duration Exposure Facility (LDEF), including materials of aluminum, vanadium, and steel trunnions were analyzed by ultra-low-level gamma spectroscopy. The study quantified particle induced activations of (sup 22)Na, {sup 46}Sc, {sup 51}Cr, {sup 54}Mn, {sup 56}Co, {sup 57}Co, {sup 58}Co, and {sup 60}Co. The samples of trunnion sections exhibited increasing activity toward the outer end of the trunnion and decreasing activity toward its radial center. The trunnion sections did not include end pieces, which have been reported to collect noticeable {sup 7}Be on their leading surfaces. No significant {sup 7}Be was detected in the samples analyzed. The Underground Counting Facility at Savannah River Laboratory (SRL) was used in this work. The facility is 50 ft. underground, constructed with low-background shielding materials, and operated as a clean room. The most sensitive analyses were performed with a 90%-efficient HPGe gamma-ray detector, which is enclosed in a purged active/passive shield. Each sample was counted for one to six days in two orientations to yield more representative average activities for the sample. The non-standard geometries of the LDEF samples prompted the development of a novel calibration method, whereby the efficiency about the samples surfaces (measured with point sources) predicted the efficiency for the bulk sample.

Winn, W.G.

1991-01-01

35

Report of the Department of Energy, Office of Environmental Management, Gamma Spectrometry Data Validation Program  

SciTech Connect

This report represents the results of analyses received on or before August 15, 1996 for the first annual Gamma Spectrometry Data Validation Program (May 1996) designed to assess the capability of DOE laboratories and DOE contractors in performing routine gamma spectra analyses. Data reduction of gamma spectra are normally performed with computer codes supplied by commercial manufacturers or are developed in house. Earlier evaluations of commercial codes gave spurious results for complex spectrum. A calibration spectrum, a background spectrum and three sample spectra of increasing complexity were included for each format. The calibration spectrum contained nuclides covering the energy range from 59.5 keV to 1836 keV. The first two samples contained fallout nuclides with halflives of over 30 days. Naturally occurring nuclides were also present. The third sample contained both short and long lived fission product nuclides. The participants were asked to report values and uncertainties as Becquerel per sample with no decay correction. Sixteen software packages were evaluated. In general, the results do not appear to be dependent on the software used. Based on the control limits established for the Program for the three sample spectra, 62%, 63% and 53%, respectively, of the reported results were evaluated as acceptable.

Decker, K.; Sanderson, C.G.; Greenlaw, P.

1996-11-01

36

Espectrometria Gama de Geometria 4 pi Infinita (Gamma Ray Spectrometry of Infinite 4 pi Geometry).  

National Technical Information Service (NTIS)

Because of the weak absorption of gamma radiation by matter, gamma-ray spectrometry may be applied to samples of great volume. A very interesting case is that of the gamma-ray spectrometry applied with 4-pi geometry around the detector on a sample assumed...

D. J. R. Nordemann

1987-01-01

37

Nondestructive measurement of neutron exposure in the BR-3 pressure vessel by continuous gamma-ray spectrometry  

SciTech Connect

Continuous gamma-ray spectrometry was used in the instrument tube of the BR-3 reactor water shield tank in an attempt to quantify the neutron exposure of the pressure vessel. A hybrid lead-natural uranium collimator-shield was used to surround the Si(Li) detectors of the Janus gamma-ray spectrometry probe. This hybrid collimator provided sufficient attenuation of the gamma field to reduce count rates to tolerable levels. Measurements were carried out at different elevations near midplane, from approximately 20 cm above to 10 cm below midplane. The dominant structure observed in these gamma-ray spectra was that of WCo, whereas the search for the VUMn gamma-ray (0.835 MeV) did not reveal any intensity above statistical fluctuations in the data. The absolute flux of WCo gamma-rays observed with the Janus probe is in good agreement with the calculated WCo flux. These calculations are based on the well-defined neutronic exposure of the BR-3 pressure vessel environment, which has been characterized on the basis of surveillance capsule dosimetry, dedicated thermal shield dosimetry sampling, and transport theory calculations. In light of this good agreement, the general applicability of continuous gamma-ray spectrometry for non-destructive neutron exposure measurements of light water reactor pressure vessels is discussed.

McNeece, J.P.; Gold, R.; Fabry, A.; DeLeeuw, S.; Gubel, P.

1984-07-01

38

Analysis of gamma-ray burst spectra with cyclotron lines  

NASA Technical Reports Server (NTRS)

Motivated by the recent developments in the cyclotron resonance upscattering of soft photons or CUSP model of Gamma Ray Burst (GBR) continuum spectra, we revisit a select database of GRBs with credible cyclotron absorption features. We measure the break energy of the continuum, the slope below the break and deduce the soft photon energy or the electron beam Lorentz factor cutoff. We study the correlation (or lack of) between various parameters in the context of the CUSP model. One surprise result is that there appears to be marginal correlation between the break energy and the spectral index below the break.

Kargatis, Vincent; Liang, Edison P.

1992-01-01

39

Basic characterization of highly enriched uranium by gamma spectrometry  

NASA Astrophysics Data System (ADS)

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.

Nguyen, Cong Tam; Zsigrai, József

2006-05-01

40

Gamma ray spectrometry of LDEF samples at SRL  

NASA Technical Reports Server (NTRS)

A total of 31 samples from the Long Duration Exposure Facility (LDEF), including materials of aluminum, vanadium, and steel trunnions were analyzed by ultra-low-level gamma spectrometry. The study quantified particle induced activations of Na-22, Sc-46, Cr-51, Mn-54, Co-56, Co-57, Co-58, and Co-60. The samples of trunnion sections exhibited increasing activity toward the outer end of the trunnion and decreasing activity toward its radial center. The trunnion sections did not include end pieces, which were reported to collect noticeable Be-7 on their leading surfaces. No significant Be-7 was detected in the samples analyzed.

Winn, Willard G.

1992-01-01

41

Gamma ray spectrometry of LDEF samples at SRS  

NASA Technical Reports Server (NTRS)

A total of 31 samples from Long Duration Exposure Facility (LDEF), including materials of Al, V, and steel trunnions were analyzed by ultralow level gamma spectrometry. The study quantified particle induced activations of Na-22, Sc-46, Cr-51, Mn-54, Co-56, Co-57, Co-58, and Co-60. The samples of trunnion sections exhibited increasing activity toward the outer end of the trunnion and decreasing activity toward its radial center. The trunnion sections did not include an end piece that collects noticeable Be-7 on its leading surface. No significant Be-7 was detected in the samples analyzed. The most sensitive analyses were performed with a 90 pct. efficient HPGe gamma ray detector, which is enclosed in a purged active/passive active shield.

Winn, Willard G.

1991-01-01

42

Initial recommendations for restricting gamma-ray spectrometry measurements of radionuclides for on-site inspections  

SciTech Connect

The US paper ?Radionuclide Sampling, Sample Handling and Analytical Laboratory Equipment for Comprehensive Test Ban Treaty On-Site Inspections,? CTBT/PC/V/OSI/WSII/PR/29 identified the radionuclides of interest to an OS1 as 144Ce, 147Nd, 141Ce, 149Ba140La), 95 Zr(95Nb), 131mXe, 133mXe, 133gXe, 135gXe, and 37Ar. All of these nuclides (except 37Ar) can be measured via some form of conventional or coincidence-based gamma-ray spectrometry. The non-gaseous radionuclides [144Ce, 147Nd, 141Ce, 140Ba(140La), and 95Zr(95Nb)] can be measured via conventional high-resolution gamma-ray spectrometry using a shielded, high-purity germanium (HPGe) detector. The gaseous radionuclides 131mXe, 133mXe, 133gXe, and 135gXe are best measured (after separation from their homologous elements) via a gamma & beta/electron coincidence technique such as that described in CTBT/WGB/TL-11/5 which could utilize either a HPGe or low-resolution (NaI(TI)) gamma-ray spectrometer to detect the gamma-ray/x-ray and a plastic scintillator to detect the beta particle/electron from the decay of the various Xe isotopes. The US paper CTBT/PC/V/IOSI/WSII/PR/29 (and other papers) identified a need to limit the information that can be extracted from high-resolution gamma-ray spectra to ensure that only information relevant to an OSI is accessible. The term ?blinding? has been used to describe the need to limit the information available to the Inspection Team from the high-resolution gamma-ray measurement. A better term is ?measurement restriction?; the need for restricting the information is particularly relevant to conventional high-resolution gamma-ray spectrometry measurements, but not to the gamma & beta/electron coincidence-type measurements envisioned for Xe isotopes because the separation process for these radionuclides will likely eliminate any other observables. The purpose of this paper is to define functional requirements for restricting measurements via conventional high- resolution gamma-ray spectrometry systems to ensure that only the nuclides of interest to an OSI can be identified and quantified. Options discussed below include 1) acquisition and analysis of the entire high-resolution gamma-ray spectrum combined with a limited reporting mechanism, and 2) restricting of the gamma-ray spectrum prior to acquisition and analysis/reporting based upon only the limited portion of the spectrum. It is well recognized that the results should be as accurate as possible, but the analytical work must be performed in a manner consistent with the purposes of an OSI.

Buckley, W. F.; Kreek, S. A.; Wild, J. F.

1998-11-06

43

Broadband Turbulent Spectra in Gamma-Ray Burst Light Curves  

NASA Astrophysics Data System (ADS)

Broadband power density spectra offer a window to understanding turbulent behavior in the emission mechanism and, at the highest frequencies, in the putative inner engines powering long gamma-ray bursts (GRBs). We describe a chirp search method alongside Fourier analysis for signal detection in the Poisson noise-dominated, 2 kHz sampled, BeppoSAX light curves. An efficient numerical implementation is described in O(Nnlog n) operations, where N is the number of chirp templates and n is the length of the light-curve time series, suited for embarrassingly parallel processing. For the detection of individual chirps over a 1 s duration, the method is one order of magnitude more sensitive in signal-to-noise ratio than Fourier analysis. The Fourier-chirp spectra of GRB 010408 and GRB 970816 show a continuation of the spectral slope with up to 1 kHz of turbulence identified in low-frequency Fourier analysis. The same continuation is observed in an average spectrum of 42 bright, long GRBs. An outlook on a similar analysis of upcoming gravitational wave data is included.

van Putten, Maurice H. P. M.; Guidorzi, Cristiano; Frontera, Filippo

2014-05-01

44

Magnetic spectrometry of deuteron spectra in NX2 plasma focus  

Microsoft Academic Search

Summary form only given. Magnetic spectrometry using polymer nuclear track detectors is used for high-resolution measurement of the energy spectrum of deuterons (> 250 keV) emitted from the pinch-column of the NX2 plasma focus (PF). The spectrum is measured for single PF shots. A 25 mum pinhole images the deuteron source on the spectrometer. This pinhole enables differential vacuum to

M. V. Roshan; A. R. Talebitaher; R. S. Rawat; P. Lee; S. V. Springham

2009-01-01

45

High-resolution gamma-ray spectrometry in uranium exploration  

USGS Publications Warehouse

Sedimentary-type uranium deposits accumulate at favorable sites along a migration path which may be kilometers in length. Their source is a large volume of rock from which the uranium has been leached. The geochemical mobilities and half lives of uranium and its daughter products vary widely so that they are transported from the source rocks, at different rates, along the migration path to their ultimate site. The radioactive disequilibrium resulting from this process has been well documented in the immediate vicinity of ore deposits, and disequilibrium is commonly recorded on gamma-ray logs up the hydraulic gradient from uranium ore. Little is known about the state of secular equilibrium in the leached host rocks, which often represent the only part of the migration path that is at or near the surface and is thus most accessible to the exploration geophysicist. High-resolution gamma-ray spectrometry provides a means of investigating the disequilibrium associated with uranium leaching and migration. Direct measurement of uranium can be made by this method, and the equivalent weight percents can be determined for six of the seven daughter-product decay groups that characterize the state of radioactive equilibrium. The technique has been used quantitatively in laboratory studies, where the results compare favorably with radiochemical analyses; field experiments suggest that semi-quantitative data may be obtained at the outcrop.

Moxham, Robert M.; Tanner, Allan B.

1977-01-01

46

Basic characterization of 233U: Determination of age and 232U content using sector field ICP-MS, gamma spectrometry and alpha spectrometry  

NASA Astrophysics Data System (ADS)

The possibility to determine the age, i.e. the time since the last chemical separation, of 233U was studied using two fundamentally different measurement techniques: inductively coupled plasma mass spectrometry (ICP-MS) and gamma spectrometry. Moreover, the isotope ratio 232U/ 233U was measured using both alpha spectrometry and gamma spectrometry. For the two materials analysed, all measurement results were in agreement, i.e. consistent within the combined uncertainties. One of the materials was also measured using gamma spectrometry under field conditions. This measurement was also in agreement with the other results on this material.

Ramebäck, H.; Nygren, U.; Lagerkvist, P.; Verbruggen, A.; Wellum, R.; Skarnemark, G.

2008-03-01

47

Analysis Software for gamma Spectrometry Developed on an IN96 Inter-Technique Multichannel Analyser.  

National Technical Information Service (NTIS)

An analysis software for gamma spectrometry has been developed and implemented on an INTERTECHNIQUE multichannel analyser (IN96). This software makes the analyser standard programs easier to use and gives solutions to several other analysis problems. Spec...

T. De Bruyne M. Silly A. Adam J. Laurec

1985-01-01

48

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

49

The continuous detection of gamma (X-ray) spectra registered during atmospheric precipitations  

NASA Astrophysics Data System (ADS)

Monitoring of a gamma radiation in a ground atmosphere layer has revealed systematic increases during precipitations (rains, snowfalls). We have designed the instrument for the continuous detecting of differential spectra of a gamma radiation on the basis of spectrometers with sizes of scintillation crystals (Ø62×20 mm) and (Ø150× 100 mm). Registration of spectra of a gamma radiation is made with high resolution by means of the 4096-channel pulse-height analyzer over the energy range from 200 keV up to 4 MeV. Responses of crystals (effectiveness of detecting) to entering radiation have been calculated with the help of GEANT4 package. Instruments posed on the continuous registration of differential spectra of a gamma-ray background. In the present paper the preliminary results of observations carried out by the new instrument are presented. Measuring of spectra during increases of the gamma (X-rays) happening during precipitations, has shown absence in the spectra the characteristic lines of any radio nuclides in all the effective range. Spectra of a X-ray radiation over the range 20-400 keV, obtained earlier on the basis of crystal Ø63×20 mm, are well compounded with the data obtained with the crystal Ø150×100 mm and simulations by GEANT4 package. Joining of two detectors gives a possibility to study spectra of a gamma (X - ray) background and their variations from 20 keV up to 4 MeV.

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

2013-02-01

50

The reference peak areas of the 1995 IAEA test spectra for gamma-ray spectrum analysis programs are absolute and traceable  

Microsoft Academic Search

A previously validated algorithm for absolute peak area determination was used to verify the reference peak areas supplied with the 1995 IAEA test spectra for gamma-ray spectrometry. These reference peak areas turn out to be absolute and traceable to a precision of 0.9%: The reference peak areas are possibly too low by a factor 0.992±0.009. It is proposed to employ

Menno Blaauw

1999-01-01

51

Dosimetrical analysis of reactor leakage gamma-rays by means of scintillation spectrometry  

Microsoft Academic Search

Exposure rates due to leakage gamma-rays from operating reactors TRIGA ; Mark II and III were measured in a horizontal plane by means of scintillation ; spectrometry using a 3'' x 3'' cylindrical NaI(Tl) detector associated with a 400 ; channel pulse height analyzer under varied conditions of reactor operation. In ; determining exposure rate due to the leakage gamma-rays

Jun

1973-01-01

52

Plutonium Isotopic Composition by gamma Spectrometry. A Code for Automatic Analysis.  

National Technical Information Service (NTIS)

This document describes an automatic analysis code for the measurement of plutonium isotopic composition by gamma spectrometry. This code is operational on a gamma analysis system (22 K Mots - 16 bits); it is used for the measurement of samples of differe...

J. Morel M. Vallee B. Chauvenet

1982-01-01

53

Recovery and reanalysis of archived airborne gamma spectrometry data from the 1991 Dounreay survey.  

PubMed

Archived Airborne Gamma Spectrometry (AGS) data from the 1991 NIREX characterisations of Caithness have been recovered. The separate gamma spectrometry and positional data streams for approximately 120,000 measurements have been combined into a single data stream using the European Radiometrics and Spectrometry (ERS) data format. An analysis using working calibration coefficients and spectral stripping procedure has verified that the original survey recorded high quality data. The converted data stream is in a format more accessible to future research use, including evaluation of environmental change in the Caithness region. PMID:21798750

Cresswell, A J

2012-01-01

54

Variations in Spectra of Resonance Neutron Capture Gamma Rays in Indium  

Microsoft Academic Search

Measurements are reported of the 0-350 kev portion of the gamma-ray spectra following neutron capture in the 1.46-, 3.86-, and 9.10-ev resonances of the 49In115 target nucleus. The prominent features of the spectra are significantly different for the three resonances as indicated by the ratios of relative intensities of the 67-, 98-, 188-, and 280-kev gamma rays. The 0-1600 kev

J. E. Draper; C. A. Fenstermacher; H. L. Schultz

1958-01-01

55

PC based analysis of gamma-ray spectra  

Microsoft Academic Search

New sophisticated gamma spectral analysis software makes a personal computer based gamma spectroscopy system more capable. The personal computer employs 512 kbytes of RAM and a 20 Mbyte hard disk. Spectral analysis uses algorithms adapted from a minicomputer version of the GAUSS V code and optimized for use on a personal computer. particular care was taken to optimize the peak

T. C. Chapman

1988-01-01

56

Waste Characterization Using Gamma Ray Spectrometry with Automated Efficiency Optimization - 13404  

SciTech Connect

Gamma ray spectrometry using High Purity Germanium (HPGe) detectors is commonly employed in assaying radioactive waste streams from a variety of sources: nuclear power plants, Department of Energy (DOE) laboratories, medical facilities, decontamination and decommissioning activities etc. The radioactive material is typically packaged in boxes or drums (for e.g. B-25 boxes or 208 liter drums) and assayed to identify and quantify radionuclides. Depending on the origin of the waste stream, the radionuclides could be special nuclear materials (SNM), fission products, or activation products. Efficiency calibration of the measurement geometry is a critical step in the achieving accurate quantification of radionuclide content. Due to the large size of the waste items, it is impractical and expensive to manufacture gamma ray standard sources for performing a measurement based calibration. For well over a decade, mathematical efficiency methods such as those in Canberra's In Situ Object Counting System (ISOCS) have been successfully employed in the efficiency calibration of gamma based waste assay systems. In the traditional ISOCS based calibrations, the user provides input data such as the dimensions of the waste item, the average density and fill height of the matrix, and matrix composition. As in measurement based calibrations, the user typically defines a homogeneous matrix with a uniform distribution of radioactivity. Actual waste containers can be quite nonuniform, however. Such simplifying assumptions in the efficiency calibration could lead to a large Total Measurement Uncertainty (TMU), thus limiting the amount of waste that can be disposed of as intermediate or low activity level waste. To improve the accuracy of radionuclide quantification, and reduce the TMU, Canberra has developed the capability to optimize the efficiency calibration using the ISOCS method. The optimization is based on benchmarking the efficiency shape and magnitude to the data available in the analyzed gamma ray spectra. Data from measurements of a given item in multiple counting geometries are among the powerful benchmarks that could be used in the optimization. Also, while assaying a waste stream with fission products and activation products emitting gamma lines of multiple energies, optimizing the efficiency on the basis of line activity consistency is very effective. In the present paper, the ISOCS- based optimization methodology is applied to measurement scenarios involving multiple counting geometries, and multi-gamma-line radionuclides. Results will be presented along with accuracy and precision estimates for each measurement. (authors)

Bosko, A.; Venkataraman, R.; Bronson, F.L.; Ilie, G.; Russ, W.R. [Canberra Industries, 800 Research Parkway, Meriden, CT 06450 (United States)] [Canberra Industries, 800 Research Parkway, Meriden, CT 06450 (United States)

2013-07-01

57

Gamma-ray burst spectra and time histories from 2 to 400 keV  

Microsoft Academic Search

The Gamma-Ray burst detector on Ginga consisted of a proportional counter to observe the x-rays and a scintillation counter to observe the gamma-rays. It was ideally suited to study the x-rays associated with gamma-ray bursts (GRBs). Ginga detected ? 120 GRBs and 22 of them had sufficient statistics to determine spectra from 2 to 400 keV. Although the Ginga and

E. E. Fenimore

1999-01-01

58

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

59

Low-frequency spectra of gamma-ray bursts  

Microsoft Academic Search

Particles with energies below the mean energy E0 in relativistic shocked plasmas should assume an equilibrium energy distribution. This leads to a synchrotron spectrum Fnu proportional to nu1\\/3 up to approximately the critical frequency nu0 of an electron with the energy E0. Application to gamma-ray bursts (GRBs) implies that a burst with 10-5 ergs\\/sq cm\\/s of soft gamma rays and

J. I. Katz

1994-01-01

60

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

Microsoft Academic Search

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

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

61

Improved computerized acquisition and analysis of gamma ray spectra  

Microsoft Academic Search

A new minicomputer based gamma spectroscopy system supports concurrent operation of up to four detectors, with 8k channels per detector. The minicomputer employs 896 kilobytes of RAM and a 25 megabyte hard disk, and runs under a multiuser operating system. Spectral analyses use algorithms adapted from the GAUSS V computer code and optimized for use on a minicomputer. Major improvements

T. C. Chapman; J. M. Gross

1984-01-01

62

Gamma spectrometry and plastic-scintillator inherent background  

SciTech Connect

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 higher energy. Attenuation lengths were calculated. The tests were based on three modes of interaction between the gamma radiation and the scintillator: Compton scattering, the photoelectric effect, and pair formation. The contribution from light collection was also considered. The scintillators tested included polystyrene, polymethyl methacrylate, cesium iodide, and sodium iodide. Gamma sources included cesium 137, sodium 22, potassium 40, yttrium 88, thorium 232, and plutonium-beryllium.

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

1988-02-01

63

Procedures to analyse (gamma)-ray spectra obtained from the ORTEC or nuclear data ND-680 system by ORTEC's analysis software packages incorporated into a separate IBM-PC computer.  

National Technical Information Service (NTIS)

A detailed description is presented for processing (gamma)-spectra produced by means of Ortec or Nuclear Data spectrometry systems on an off-line IBM-PC. The ORTEC analysis software packages were transferred to and implemented on the PC A/T, and the diffe...

Zhang Xiu Zhen

1990-01-01

64

ADONIS, high count-rate HP-Ge {gamma} spectrometry algorithm: Irradiated fuel assembly measurement  

SciTech Connect

ADONIS is a digital system for gamma-ray spectrometry, developed by CEA. This system achieves high count-rate gamma-ray spectrometry with correct dynamic dead-time correction, up to, at least, more than an incoming count rate of 3.10{sup 6} events per second. An application of such a system at AREVA NC's La Hague plant is the irradiated fuel scanning facility before reprocessing. The ADONIS system is presented, then the measurement set-up and, last, the measurement results with reference measurements. (authors)

Pin, P. [AREVA NC La Hague - Nuclear Measurement Team, 50444 Beaumont-Hague Cedex (France); Barat, E.; Dautremer, T.; Montagu, T. [CEA - Saclay, LIST, Electronics and Signal Processing Laboratory, 91191 Gif sur Yvette (France); Normand, S. [CEA - Saclay, LIST, Sensors and Electronic Architectures Laboratory, 91191 Gif sur Yvette (France)

2011-07-01

65

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.

66

CdWO\\/sub 4\\/ crystal in gamma-ray spectrometry  

Microsoft Academic Search

The properties of CdWO4 (CWO) crystals in gamma spectrometry were studied. Several small samples of 10times10times3 mm size, typically used in CT X-ray detectors, were tested and then compared to the performance of a larger crystal of 20 mm in diameter and 20 mm in height. The light output, energy resolution, and nonproportionality of the CWO response versus gamma-ray energy,

M. Moszynski; M. Balcerzyk; M. Kapusta; A. Syntfeld; D. Wolski; G. Pausch; J. Stein; P. Schotanus

2005-01-01

67

On the spectra and pulse profiles of gamma-ray pulsars  

NASA Technical Reports Server (NTRS)

We model spectra and pulse profiles of gamma-ray pulsars assuming that the pulsar's magnetic axis is nearly aligned with its rotation axis. In this model, the nonthermal energy of electrons flowing outward along field lines connected to the light cylinder is efficiently converted to gamma rays via magnetic Compton scattering of optical and soft X-ray photons. The hard photons initiate a pair cascade in the pulsar magnetosphere through magnetic pair production followed by synchrotron emission. The calculated spectra are used to fit gamma-ray pulsar observations. This model produces a hollow cone of emission which can reproduce both the broad single-peaked and narrow double-peaked pulse profiles observed from gamma-ray pulsars.

Sturner, Steven J.; Dermer, Charles D.

1994-01-01

68

Transmitted photon spectra of gamma rays through a soil medium  

SciTech Connect

The transmitted photon spectra of [sup 133]Ba, [sup 137]Cs, and [sup 60]Co sources are measured through different thicknesses of a soil medium. A multiple-scatter peak is observed at an energy of 100 keV independent of incident photon energy and thickness of the medium. A linear relationship between the effective atomic number of the medium and the multiple-scatter peak energy is observed.

Singh, M.; Brar, G.S.; Mudahar, G.S. (Punjabi Univ., Patiala (India). Dept. of Physics)

1993-07-01

69

Pulse profiles and spectra of gamma ray pulsars in the polar cap model  

Microsoft Academic Search

We investigate predictions for pulse profiles and spectra of gamma-ray pulsars in the polar cap curvature radiation-initiated cascade model. In this model, the gamma-ray beam is a hollow cone centered on the magnetic pole, producing either double-peaked or single-peaked pulse profiles depending on observer orientation. We have computed simulated distributions of pulse peak phase separation seen by observers at random

Alice K Harding; Joseph K Daugherty

1998-01-01

70

Gamma-ray pulsars: the pulse profiles and phase-resolved spectra of Geminga  

Microsoft Academic Search

We present a calculation of a three-dimensional pulsar magnetosphere model to explain high-energy emission from the Geminga pulsar with a thick outer gap. High-energy gamma-rays are produced by primary accelerated particles with a power-law energy distribution through curvature radiation inside the outer gap. We also calculate the emission pattern, pulse profile and phase-resolved spectra of high-energy gamma-rays of the Geminga

L. Zhang; K. S. Cheng

2001-01-01

71

Consistency of time dilation in temporal profiles and spectra of gamma-ray bursts  

NASA Technical Reports Server (NTRS)

If gamma-ray bursters are at cosmological distances-a possibility suggested by their isotropic distribution and spatial inhomogeneity-then the temporal profiles and spectra of more distant sources will be time dilated compared to those of relatively nearby sources. Analyses of bright and dim Burst and Transient Source Experiment (BATSE) gamma-ray bursts yield a relative time-dilation factor of 2.3 on timescales of pulses and event durations. We redshift the spectra of time intervals near the intensity peaks of the bright sample on a trial grid and compare with spectra of the dim sample. A redshift factor of order two-with wide latitude permitted-brings the spectra of the two brightness groups into alignment. Thus there is coarse agreement with the time-dilation factor found in the temporal domain.

Noriss, J. P.; Nemiroff, R. J.; Bonnell, J. T.; Scargle, J. D.; Davis, S. P.; Kouveliotou, C.; Pendleton, G.; Fishman, G. J.; Meegan, C. A.; Paciesas, W. S.

1995-01-01

72

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

Microsoft Academic Search

We discuss the determination of energy region (bin) boundaries and decision metrics for gamma-ray spectra, acquired using a mid-resolution detector, that are useful for detecting illicit sources at low total counts. The bins are designed to produce the lowest minimum detectable counts using a spectral comparison ratio technique at a given false-positive rate for a specified population of benign-source spectra.

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

2007-01-01

73

VARIATIONS IN SPECTRA OF RESONANCE NEUTRON CAPTURE GAMMA RAYS IN INDIUM  

Microsoft Academic Search

Measurements are reported of the 0 to 350 kev portion of the gamma-ray ; spectra following neutron capture in the 1.46-, 3.86-, and 9.10-ev resonances of ; the ââIn¹¹⁵ target nucleus. The prominent features of the spectra ; are significantly different for the three resonances as indicated by the ratios ; of relative intensities of the 67-, 98-, 188-. and

J. E. Draper; C. A. Fenstermacher; H. L. Schultz

1958-01-01

74

Analysis for naturally occuring radionuclides at environmental concentrations by gamma spectrometry  

Microsoft Academic Search

The analytical potential of low level, high resolution gamma-ray spectrometry for naturally occurring radionuclides at environmental levels is described, with particular emphasis on detector background levels and sensitivity. Comparisons are drawn between the performance of a specially designed low background detector system, and that of standard off the shelf devices. Sample characteristics, calibration procedures and checks, are described, and empirical

A. S. Murray; R. Marten; A. Johnston; P. Martin

1987-01-01

75

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

76

Spatially-Aware Temporal Anomaly Mapping of Gamma Spectra  

NASA Astrophysics Data System (ADS)

For security, environmental, and regulatory purposes it is useful to continuously monitor wide areas for unexpected changes in radioactivity. We report on a temporal anomaly detection algorithm which uses mobile detectors to build a spatial map of background spectra, allowing sensitive detection of any anomalies through many days or months of monitoring. We adapt previously-developed anomaly detection methods, which compare spectral shape rather than count rate, to function with limited background data, allowing sensitive detection of small changes in spectral shape from day to day. To demonstrate this technique we collected daily observations over the period of six weeks on a 0.33 square mile research campus and performed source injection simulations.

2014-06-01

77

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

78

Concurrent Measurement of Individual Gamma-Ray Spectra During and Between Fast Neutron Pulses  

Microsoft Academic Search

A fast commercial digital multi-channel analyzer (DMCA) with a 40 MHz sampling frequency, was modified for concurrent acquisition during the same data collection run, of two separate gamma-ray spectra induced during and between fast neutron pulses. The DMCA was programmed to monitor the incoming and observed count rates, and the resulting real times and dead times separately for each spectrum.

S. Mitra; L. Wielopolski; H. Tan; A. Fallu-Labruyere; W. Hennig; W. K. Warburton

2007-01-01

79

Analyses of uranium and actinium gamma spectra: an application to measurements of environmental contamination  

Microsoft Academic Search

A system for the reduction of the complex gamma spectra of nuclides in the uranium, actinium, and thorium series, tailored to calculation of line intensities, analyses of errors, and identification of nuclides is described. This system provides an efficient technique for characterizing contamination in the environs of uranium mines and mills. Identification of the nuclides and calculation of their concentrations

Momeni

1981-01-01

80

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

Microsoft Academic Search

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

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

2006-01-01

81

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...

82

Gamma dose rate calculation and mapping of piemonte (North-West Italy) from gamma spectrometry soil data.  

PubMed

In this study the air gamma dose rate map of Piemonte, a region in the North-West of Italy, was produced from gamma spectrometry soil data. Soil samples collected in 110 different sites of Piemonte were analysed with Hyperpure Germanium (HPGe) detectors (30% relative efficiency), which allow the evaluation of the activity concentrations of natural radionuclides and (137)Cs. Then, using the available mathematical models, the gamma absorbed dose rate in air due to radionuclides was calculated. The contribution of the cosmic radiation to the total absorbed dose rate, which depend on the site altitude was also evaluated and added to the soil contribution. Finally, the map of the whole region was obtained by fitting the dose rate values of the different sites with kriging algorithms. PMID:15550714

Losana, M C; Magnoni, M; Bertino, S; Procopio, S; Facchinelli, A; Sacchi, E

2004-01-01

83

Irregularity in gamma ray source spectra as a signature of axionlike particles  

NASA Astrophysics Data System (ADS)

Oscillations from high-energy photons into light pseudoscalar particles in an external magnetic field are expected to occur in some extensions of the standard model. It is usually assumed that those axionlike particles (ALPs) could produce a drop in the energy spectra of gamma ray sources and possibly decrease the opacity of the Universe for TeV gamma rays. We show here that these assumptions are in fact based on an average behavior that cannot happen in real observations of single sources. We propose a new method to search for photon-ALP oscillations, taking advantage of the fact that a single observation would deviate from the average expectation. Our method is based on the search for irregularities in the energy spectra of gamma ray sources. We predict features that are unlikely to be produced by known astrophysical processes and a new signature of ALPs that is easily falsifiable.

Wouters, Denis; Brun, Pierre

2012-08-01

84

Gamma-ray spectra and decay heat following U-235 thermal neutron fission  

NASA Astrophysics Data System (ADS)

Gamma-ray energy spectra have been measured for aggregate fission products resulting from the thermal neutron- induced fission of 235Su. The measurements were performed using a well shielded 5/prime' x 5/prime' NaI(Tl) spectrometer in conjunction with beta-gamma gating for background reduction and for precise definition of the delay times spanning a range 0.25-14000s, with approximately three mean delay times per decade. Fission products were transferred to the detectors by a helium-jet/tape transport system, providing the capability for measurements at much shorter delay times than have been previously reported. Gamma-ray spectra were unfolded using a library of measured spectrometer response functions and the programs NGRC and CRSUP, developed as part of this project, to obtain the gamma-ray energy distribution for each delay time. The relative gamma-ray decay heat was determined from the average energy of each distribution in combination with the measured gamma-to-beta activity ratio and the relative beta activity as a function of delay time. This decay heat has been compared with summation calculations using the CINDER10 program and ENDF/B-VI fission-product data, as well as with the results of previous studies.

Nguyen, Hung Van

1997-09-01

85

Some applications of gamma absorptiometry and spectrometry for the control of nuclear materials  

NASA Astrophysics Data System (ADS)

In nuclear fuels, and neutrons absorbers used in control rods, the thermal power generated is locally dependent on the concentration of the fissile or absorbing nucleus. In order to control the homogeneity of such materials, non-destructive methods using either gamma absorptiometry or gamma spectrometry were developed; some applications of these methods are presented in this paper. The fuel of the High Temperature Reactor (HTR) is frequently composed of UO 2 and ThO 2 spherical particles dispersed in a carbon matrix; the axial distribution of the particles along the fuel rods can be controlled in two ways: with gamma absorptiometry the heavy elements atoms (U+Th) can be detected but without discrimination between U and Th; with gamma spectrometry, separate distributions of uranium and thorium, deduced from the intensity of characteristic gamma rays are obtained. In nuclear power plants (PWR, FBR) the control rods are made usually with boron carbide (B 4C) pellets. By mean of gamma absorptiometry scanning the density distribution along the axis and the radius of the pellets are obtained. The originality of the method consists in the use of a self-calibration process, then the knowledge of the mass absorption coefficient is not required to perform the examinations. A computerized apparatus has been developed for these controls.

Guery, M.

1991-02-01

86

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

87

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

88

Measurement of Branching Fractions and Mass Spectra of B to K pi pi gamma  

SciTech Connect

The authors present a measurement of the partial branching fractions and mass spectra of the exclusive radiative penguin processes B {yields} K{pi}{pi}{gamma} in the range m{sub K{pi}{pi}} < 1.8 GeV/c{sup 2}. They reconstruct four final states: K{sup +}{pi}{sup -}{pi}{sup +}{gamma}, K{sup +}{pi}{sup -}{pi}{sup 0}{gamma}, K{sub S}{sup 0}{pi}{sup -}{pi}{sup +}{gamma}, and K{sub S}{sup 0}{pi}{sup +}{pi}{sup 0}{gamma}, where K{sub S}{sup 0} {yields} {pi}{sup +}{pi}{sup -}. Using 232 million e{sup +}e{sup -} {yields} B{bar B} events recorded by the BABAR experiment at the PEP-II asymmetric-energy storage ring, they measure the branching fractions {Beta}(B{sup +} {yields} K{sup +}{pi}{sup -}{pi}{sup +}{gamma}) = (2.95 {+-} 0.13(stat.) {+-} 0.20(syst)) x 10{sup -5}, {Beta}(B{sup 0} {yields} K{sup +}{pi}{sup -}{pi}{sup 0}{gamma}) = (4.07 {+-} 0.22(stat.) {+-} 0.31(syst.)) x 10{sup -5}, {Beta}(B{sup 0} {yields} K{sup 0}{pi}{sup +}{pi}{sup -}{gamma}) = (1.85 {+-} 0.21(stat.) {+-} 0.12(syst.)) x 10{sup -5}, and {Beta}(B{sup +} {yields} K{sup 0}{pi}{sup +}{pi}{sup 0}{gamma}) = (4.56 {+-} 0.42(stat.) {+-} 0.31(syst.)) x 10{sup -5}.

Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Tisserand, V.; Zghiche, A.; /Annecy, LAPP; Grauges, E.; /Barcelona, IFAE; Palano, A.; Pappagallo, M.; Pompili, A.; /Bari U. /INFN, Bari; Chen, J.C.; Qi, N.D.; Rong, G.; Wang, P.; Zhu, Y.S.; /Beijing, Inst. High Energy Phys.; Eigen, G.; Ofte, I.; Stugu, B. /Bergen U. /LBL, Berkeley /UC, Berkeley /Birmingham U. /Ruhr U., Bochum /Bristol U. /British Columbia U. /Brunel U. /Novosibirsk, IYF /UC, Irvine /UCLA /UC, Riverside /UC, San Diego /UC, Santa Barbara /UC, Santa Cruz /Caltech /Cincinnati U. /Colorado U. /Colorado State U. /Dortmund U. /Dresden, Tech. U. /Ecole Polytechnique /Edinburgh U. /Ferrara U. /INFN, Ferrara /Frascati /Genoa U. /INFN, Genoa /Harvard U. /Heidelberg U. /Imperial Coll., London /Iowa U. /Iowa State U. /Orsay, LAL /LLNL, Livermore /Liverpool U. /Queen Mary, U. of London /Royal Holloway, U. of London /Louisville U. /Manchester U. /Maryland U. /Massachusetts U., Amherst /MIT, LNS /McGill U. /Milan U. /INFN, Milan /Mississippi U. /Montreal U. /Mt. Holyoke Coll. /Naples U. /INFN, Naples /NIKHEF, Amsterdam /Notre Dame U. /Ohio State U. /Oregon U. /INFN, Padua /Padua U. /Paris U., VI-VII /Pennsylvania U. /Perugia U. /INFN, Perugia /Pisa U. /Pisa, Scuola Normale Superiore /INFN, Pisa /Prairie View A-M /Princeton U. /Rome U. /INFN, Rome /Rostock U. /Rutherford /DAPNIA, Saclay /South Carolina U. /SLAC /Stanford U., Phys. Dept. /SUNY, Albany /Tennessee U. /Texas U. /Texas U., Dallas /Turin U. /INFN, Turin /Trieste U. /INFN, Trieste /Valencia U., IFIC /Vanderbilt U. /Victoria U. /Warwick U. /Wisconsin U., Madison /Yale U.

2005-07-12

89

Development of isotope dilution gamma-ray spectrometry for plutonium analysis  

SciTech Connect

We are studying the feasibility of determining the plutonium concentration and isotopic distribution of highly radioactive, spent-fuel dissolver solutions by employing high-resolution gamma-ray spectrometry. The study involves gamma-ray plutonium isotopic analysis for both dissolver and spiked dissolver solution samples, after plutonium is eluted through an ion-exchange column and absorbed in a small resin bead bag. The spike is well characterized, dry plutonium containing {approximately}98% of {sup 239}Pu. By using measured isotopic information, the concentration of elemental plutonium in the dissolver solution can be determined. Both the plutonium concentration and the isotopic composition of the dissolver solution obtained from this study agree well with values obtained by traditional isotope dilution mass spectrometry (IDMS). Because it is rapid, easy to operate and maintain, and costs less, this new technique could be an alternative method to IDMS for input accountability and verification measurements in reprocessing plants. 7 refs., 4 figs., 4 tabs.

Li, T.K.; Parker, J.L. (Los Alamos National Lab., NM (United States)); Kuno, Y.; Sato, S.; Kurosawa, A.; Akiyama, T. (Power Reactor and Nuclear Fuel Development Corp., Tokai, Ibaraki (Japan))

1991-01-01

90

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

91

Correction for radon distribution in solid/liquid and air phases in gamma-ray spectrometry.  

PubMed

The effect of radon diffusion and distribution between a (226)Ra matrix and the top air gap inside sample containers for gamma-ray spectrometry was studied. Containers filled at almost 100% or just 70% of total capacity yielded correction factors of about 7% and 20% respectively. Applying these correction factors allowed activity values calculated from (226)Ra or radon decay products to agree within 2%. PMID:22476014

Carconi, P; Cardellini, F; Cozzella, M L; De Felice, P; Fazio, A

2012-09-01

92

Epithermal neutron activation analysis of uranium by neptunium-239 using high resolution gamma-spectrometry  

Microsoft Academic Search

The possibility to use the most intensive gamma-peak of239Np for INAA of uranium with epithermal neutrons and high resolution Ge(Li)-spectrometry is evaluated. A way for calculation\\u000a of the peak area of overlapping peaks of153Sm and239Np is proposed. This can be used in other similar cases in the practice of NAA. On this basis a scheme for NAA of uranium\\u000a in

I. Kuleff; K. Kostadinov

1981-01-01

93

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

94

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

SciTech Connect

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 of detector position behind these materials. The measured data were obtained using a NE-213 liquid scintillator using pulse-shape discrimination methods to resolve neutron and gamma ray pulse height data and spectral unfolding methods to convert these data to energy spectra. The calculated data were obtained using two-dimensional discrete ordinates radiation transport methods in a complex calculational network that takes into account the energy-angle dependence of the D-T neutrons and the nonphysical anomalies of the S/sub n/ method.

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

1980-08-01

95

The spectra program library: A PC based system for gamma-ray spectra analysis and INAA data reduction  

USGS Publications Warehouse

A PC based system has been developed for the analysis of gamma-ray spectra and for the complete reduction of data from INAA experiments, including software to average the results from mulitple lines and multiple countings and to produce a final report of analysis. Graphics algorithms may be called for the analysis of complex spectral features, to compare the data from alternate photopeaks and to evaluate detector performance during a given counting cycle. A database of results for control samples can be used to prepare quality control charts to evaluate long term precision and to search for systemic variations in data on reference samples as a function of time. The entire software library can be accessed through a user-friendly menu interface with internal help.

Baedecker, P. A.; Grossman, J. N.

1995-01-01

96

NMIS With Gamma Spectrometry for Attributes of Pu and HEU, Explosives and Chemical Agents  

SciTech Connect

The concept for the system described herein is an active/passive Nuclear Materials Identification System{sup 2} (NMIS) that incorporates gamma ray spectrometry{sup 3}. This incorporation of gamma ray spectrometry would add existing capability into this system. This Multiple Attribute System can determine a wide variety of attributes for Pu and highly enriched uranium (HEU) of which a selected subset could be chosen. This system can be built using commercial off the shelf (COTS) components. NMIS systems are at All-Russian Scientific Research Institute of Experimental Physics (VNIIEF) and Russian Federal Nuclear Center Institute of Technical Physics, (VNIITF) and measurements with Pu have been performed at VNIIEF and analyzed successfully for mass and thickness of Pu. NMIS systems are being used successfully for HEU at the Y-12 National Security Complex. The use of active gamma ray spectrometry for high explosive HE and chemical agent detection is a well known activation analysis technique, and it is incorporated here. This report describes the system, explains the attribute determination methods for fissile materials, discusses technical issues to be resolved, discusses additional development needs, presents a schedule for building from COTS components, and assembly with existing components, and discusses implementation issues such as lack of need for facility modification and low radiation exposure.

Mihalczo, J. T.; Mattingly, J. K.; Mullens, J. A.; Neal, J. S.

2002-05-10

97

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 MCNPX(TM) 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 (214)Bi 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 (226)Ra was calculated from laboratory gamma spectrometry measurements, and the concentrations of unattached and attached (214)Bi were measured using the FRITRA4 device (SMM-Prague). We present a comparison of the experimental results with results calculated by the MCNPX(TM) 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

98

Use of Gamma Spectrometry Method for Environmental Monitoring in the area of NPP  

NASA Astrophysics Data System (ADS)

It is generally not possible to correctly determine the long and short term impact of human activity upon the environment, without thorough processing of data, obtained through monitoring. It was confirmed that such impact on the environment must be monitored over a long time period. The data obtained must be of high quality, an attribute assured by present state of scientific knowledge. One of the well established methods for monitoring atmospheric deposition of radionuclides in the environment is laboratory and in situ gamma spectrometry. With the aim to monitor an occurrence of a one-time escape or persistent release of fission products into the air, resulting from an operation of a nuclear plant, two types of monitoring are performed: i/ measurement of samples from the environment (Schreber moss, forest humus, pine bark, mushrooms and forest berries) using laboratory gamma spectrometry method in the range up to 3 MeV (those data are used for the trend analysis and for the construction of the contaminationmaps); ii/ in situ gama spectrometry for assessment dosimetry and spectrometry characteristic of photon-fields (those data are used for the dose rate calculation).

Thinova, L.; Cechak, T.; Kluson, J.; Trojek, T.

2006-05-01

99

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

Microsoft Academic Search

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

Winn

1999-01-01

100

The nature of absorption features in the spectra of gamma-ray bursts  

Microsoft Academic Search

The nature of the observed absorption features in the spectra of gamma-ray bursts of energy epsilon = 30-60 keV is discussed. It is supposed that their formation is connected with photoabsorption near the K-threshold of heavy elements (e.g. Ba, I) thrown out after a nuclear explosion as a result of the fission of superheavy nuclei. An attempt is made to

G. S. Bisnovatyi-Kogan; A. F. Illarionov

1989-01-01

101

Measurement of TeV gamma-ray spectra with the Cherenkov imaging technique  

Microsoft Academic Search

In this paper, we seek to establish reliable methods for extracting energy spectra for TeV gamma-ray sources observed using the atmospheric Cherenkov Imaging Technique. Careful attention has been paid to the calculation of the telescope gain, and we obtain good agreement between direct measurements, with a statistical error of about 10%, and an absolute calibration from the background cosmic-ray trigger

G. Mohanty; S. Biller; D. A. Carter-Lewis; D. J. Fegand; A. M. Hillas; R. C. Lamb; T. C. Weekes; J. Zweerink

1998-01-01

102

Use of MCNP + GADRAS in Generating More Realistic Gamma-Ray Spectra for Plutonium and HEU Objects  

SciTech Connect

The ability to accurately simulate high-resolution gamma spectra from materials that emit both neutrons and gammas is very important to the analysis of special nuclear materials (SNM), e.g., uranium and plutonium. One approach under consideration has been to combine MCNP and GADRAS. This approach is expected to generate more accurate gamma ray spectra for complex three-dimensional geometries than can be obtained from one-dimensional deterministic transport simulations (e.g., ONEDANT). This presentation describes application of combining MCNP and GADRAS in simulating plutonium and uranium spectra.

Rawool-Sullivan, Mohini [Los Alamos National Laboratory; Mattingly, John [North Carolina State University; Mitchell, Dean [Sandia National Laboratory

2012-08-07

103

Gamma-ray burst spectra and the hardness-intensity correlation  

NASA Astrophysics Data System (ADS)

We have performed a global study of gamma-ray burst spectra using the moderate time and energy resolution CONT data from BATSE. These data have 2 s temporal resolution in 16 energy channels that span the range of approximately 20 keV to 1.8 MeV. Spectral fits were created for a large ensemble of gamma-ray bursts. We present distributions of the peak energies in ??, and discuss the burst hardness-intensity correlation. To analyze this correlation, bursts must be ranked according to their intensity. We have investigated the effect of how the intensity definition influences the resulting correlation by using the peak flux on several timescales as the definition of burst intensity. It is shown that longer timescales tend to weaken the hardness-intensity correlation, although the correlation remains for all definitions of intensity that were examined, and is consistent with the effect expected from a cosmological distribution of gamma-ray bursts.

Mallozzi, Robert S.; Pendleton, Geoffrey N.; Paciesas, William S.; Preece, Robert D.; Briggs, Michael S.

1998-05-01

104

Gamma-Ray Spectra Due to Cosmic-Ray Interactions with Dense Gas Clouds  

NASA Astrophysics Data System (ADS)

Gamma-ray spectra from cosmic-ray proton and electron interactions with dense gas clouds have been calculated using a Monte Carlo event simulation code, GEANT4. Such clouds are postulated as a possible form of baryonic dark matter in the universe. The simulation fully tracks the cascade and transport processes that are important in a dense medium, and the resulting gamma-ray spectra are computed as a function of cloud column density. These calculations are used for predicting the Galactic diffuse gamma-ray spectrum that may be contributed by baryonic dark matter; the results are compared with data from the EGRET instrument and used to constrain the fraction of Galactic dark matter that may be in the form of dense gas clouds. In agreement with previous authors, we find useful constraints on the fraction of Galactic dark matter that may be in the form of low column density clouds (?<~10gcm-2). However, this fraction rises steeply in the region of ?~102gcm-2, and for ?>~200gcm-2 we find that baryonic dark matter models are virtually unconstrained by the existing gamma-ray data.

Ohishi, Michiko; Mori, Masaki; Walker, Mark

2004-08-01

105

Gamma-Ray Spectra due to Cosmic-Ray Interactions with Dense Gas Clouds  

NASA Astrophysics Data System (ADS)

Gamma-ray spectra from cosmic-ray proton and electron interactions with dense gas clouds have been calculated using a Monte Carlo event simulation code, GEANT4. Such clouds are postulated as a possible form of baryonic dark matter in the Universe. The simulation fully tracks the cascade and transport processes which are important in a dense medium, and the resulting gamma-ray spectra are computed as a function of cloud column-density. These calculations are used for predicting the Galactic diffuse gamma-ray spectrum which may be contributed by baryonic dark matter; the results are compared with data from the EGRET instrument, and used to constrain the fraction of Galactic dark matter which may be in the form of dense gas clouds. In agreement with previous authors, we find useful constraints on the fraction of Galactic dark matter which may be in the form of low column-density clouds (?<~10 g cm-2). However, this fraction rises steeply in the region ? ~ 102 g cm-2, and for ?>~200 g cm-2 we find that baryonic dark matter models are virtually unconstrained by the existing gamma-ray data.

Ohishi, Michiko; Mori, Masaki; Walker, Mark

2005-02-01

106

Use of delayed gamma spectra for detection of actinides (U,Pu) by photofission  

NASA Astrophysics Data System (ADS)

The development of non-destructive methods to inspect nuclear waste containers is important for radioactive waste management and non proliferation purposes. Among methods using nuclear radiation as a probe, instrumental photon activation analysis (IPAA) seems to be a promising way forward. We have previously developed an IPAA method to determine the mass of actinides in radioactive waste sealed in concrete by counting the delayed neutron emission after photofission. This method does not determine the nature of the actinides detected. Such additional useful information may, however, be derived from analysis of the delayed gamma emission spectrum. The main topic of this paper is to show how analysis of the delayed gamma spectra may overcome some of the limitations of delayed neutron analysis. Target samples of 93% and 25% enriched 235U and Pu were irradiated with bremsstrahlung gamma-rays produced by 15-MeV electrons from a linear accelerator. The gamma-rays spectra for each of the two uranium isotopes studied reveals a distinctive intensity distribution which is the consequence of modification of light-wing fission products distribution.

Gmar, M.; Capdevila, J. M.

1999-02-01

107

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

108

Intercomparison of efficiency transfer software for gamma-ray spectrometry.  

PubMed

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. For carefully examining these results and trying to derive information for improving the computation codes, this study was limited to a few simple cases. The first part concerns the simplest case of geometry transfer, i.e., using point sources for 3 source-to-detector distances: 2, 5 and 20 cm; the second part deals with transfer from point source geometry to cylindrical geometry with three different matrices. The general conclusion is that the deviations between the computed results and the measured efficiencies are mostly within 10%. The quality of the results is rather inhomogeneous and shows that these codes cannot be used directly for metrological purposes. However, most of them are operational for routine measurements when efficiency uncertainties of 5-10% can be sufficient. PMID:11545502

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

2001-10-01

109

Combinatorial approach for large-scale identification of linked peptides from tandem mass spectrometry spectra.  

PubMed

The combination of chemical cross-linking and mass spectrometry has recently been shown to constitute a powerful tool for studying protein-protein interactions and elucidating the structure of large protein complexes. However, computational methods for interpreting the complex MS/MS spectra from linked peptides are still in their infancy, making the high-throughput application of this approach largely impractical. Because of the lack of large annotated datasets, most current approaches do not capture the specific fragmentation patterns of linked peptides and therefore are not optimal for the identification of cross-linked peptides. Here we propose a generic approach to address this problem and demonstrate it using disulfide-bridged peptide libraries to (i) efficiently generate large mass spectral reference data for linked peptides at a low cost and (ii) automatically train an algorithm that can efficiently and accurately identify linked peptides from MS/MS spectra. We show that using this approach we were able to identify thousands of MS/MS spectra from disulfide-bridged peptides through comparison with proteome-scale sequence databases and significantly improve the sensitivity of cross-linked peptide identification. This allowed us to identify 60% more direct pairwise interactions between the protein subunits in the 20S proteasome complex than existing tools on cross-linking studies of the proteasome complexes. The basic framework of this approach and the MS/MS reference dataset generated should be valuable resources for the future development of new tools for the identification of linked peptides. PMID:24493012

Wang, Jian; Anania, Veronica G; Knott, Jeff; Rush, John; Lill, Jennie R; Bourne, Philip E; Bandeira, Nuno

2014-04-01

110

Direct Exposure Probe/Mass Spectrometry and Pyrolysis-Gas Chromatography/Mass Spectrometry Study of the Effect of Gamma Radiation Exposure on the Thermal Degradation Products of Natural Rubber Polycaprolactone Mixtures.  

National Technical Information Service (NTIS)

This report describes the results of direct exposure probe-mass spectrometry and pyrolysis gas chromatography/mass spectrometry studies of the effect of gamma radiation exposure on the thermal degradation products of natural rubber, polycaprolactone, 70-3...

J. A. Hiltz T. Foster

1995-01-01

111

Application of a simple peak shape function for the evaluation of gamma and X-ray spectra  

Microsoft Academic Search

The computational method for the rapid evaluation of gamma and X-ray spectra observed by semiconductor detectors in radiometric\\u000a analysis in presented using a simple peak shape function. The computer programme includes a minimizing routine based on the\\u000a modified Newton-Raphson method giving a minimized vector of the parameters more rapidly than the conventional approach. The\\u000a spectra of some gamma-ray emitting fission

T. ?ó?towski; J. Kierzek; J. Parus; R. Brzoza-Brzezina

1976-01-01

112

alpha-Particle and gamma-ray spectrometry of a plutonium solution for impurity determination.  

PubMed

A highly enriched (240)Pu solution was measured by alpha-particle and gamma-ray spectrometry to determine other radionuclides present in the material as impurities. Low activities of (238)Pu, (241)Am, (243)Cm and (244)Cm were determined by measuring thin sources, made from the original solution, in a high-resolution alpha-particle spectrometer. The sources were prepared by evaporating the plutonium solution on quartz plates in a vacuum chamber. From the ingrowth of (241)Am in the original solution, the amount of (241)Pu could be calculated. After radiochemical separation of (241)Am, the plutonium was measured by high-efficiency alpha-particle spectrometry to determine the amount of (238)Pu. The enriched (240)Pu material was also measured by high-resolution gamma-ray spectrometry, using two different HPGe detectors to determine the impurities of (239)Pu and (241)Am. The preparation of the sources and the measurement methods are described and discussed. The measured impurities, given in % of the (240)Pu activity, are compared with the values on the certificate. PMID:18356064

Sibbens, G; Altzitzoglou, T; Benedik, L; Pommé, S; Van Ammel, R

2008-01-01

113

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

114

Assay for uranium and determination of disequilibrium by means of in situ high resolution gamma-ray spectrometry  

USGS Publications Warehouse

Two sealed sondes, using germanium gamma-ray detectors cooled by melting propane, have been field tested to depths of 79 m in water-filled boreholes at the Pawnee Uranium Mine in Bee Co., Texas. When, used as total-count devices, the sondes are comparable in logging speed and counting rate with conventional scintillation detectors for locating zones of high radioactivity. When used with a multichannel analyzer, the sondes are detectors with such high resolution that individual lines from the complex spectra of the uranium and thorium series can be distinguished. Gamma rays from each group of the uranium series can be measured in ore zones permitting determination of the state of equilibrium at each measurement point. Series of 10-minute spectra taken at 0.3- to 0.5-m intervals in several holes showed zones where maxima from the uranium group and from the 222Rn group were displaced relative to each other. Apparent excesses of 230Th at some locations suggest that uranium-group concentrations at those locations were severalfold greater some tens of kiloyears, ago. At the current state of development a 10-minute count yields a sensitivity of about 80 ppm U308. Data reduction could in practice be accomplished in about 5 minutes. The result is practically unaffected by disequilibrium or radon contamination. In comparison with core assay, high-resolution spectrometry samples a larger volume; avoids problems due to incomplete core recovery, loss of friable material to drilling fluids, and errors in depth and marking; and permits use of less expensive drilling methods. Because gamma rays from the radionuclides are accumulated simultaneously, it also avoids the problems inherent in trying to correlate logs made in separate runs with different equipment. Continuous-motion delayed-gamma activation by a 163-?g 252Cf neutron source attached to the sonde yielded poor sensitivity. A better neutron-activation method, in which the sonde is moved in steps so as to place the detector at the previous activation point, could not be evaluated because of equipment failure.

Tanner, Allan B.; Moxham, Robert M.; Senftle, F. E.

1977-01-01

115

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

116

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

117

Measurement of gamma radiation levels in soil samples from Thanjavur using gamma-ray spectrometry and estimation of population exposure.  

PubMed

This study assesses the level of terrestrial gamma radiation and associated dose rates from the naturally occurring radionuclides (232)Th, (238)U and (40)K in 10 soil samples collected from Thanjavur (Tamil Nadu, India) using gamma-ray spectrometry. The activity profile of radionuclides has clearly showed the existence of low level activity in Thanjavur. The geometric mean activity concentrations of (232)Th, (238)U and (40)K is 42.9+/-9.4 Bq.kg(-1), 14.7+/-1.7 Bq.kg(-1) and 149.5+/-3.1 Bq.kg(-1) respectively are derived from all the soil samples studied. The activity concentration of (232)Th, (238)U and (40)K in soil is due to the presence of metamorphic rocks like shale, hornblende-biotite gneiss and quartzofeldspathic gneiss in these areas. Gamma absorbed dose rates in air outdoors were calculated to be in the range between 32 nGy.h(-1) and 59.1 nGy.h(-1) with an arithmetic mean of 43.3 +/-9 nGy.h(-1). This value is lesser than the population weighted world-averaged of 60 nGy.h(-1). Inhabitants of Thanjavur are subjected to external gamma radiation exposure (effective dose) ranging between 39.2 and 72.6 muSv.y(-1) with an arithmetic mean of 53.1+/-11 muSv.y(-1). The values of the external hazard index determined from the soil radioactivity of the study area are less than the recommended safe levels. PMID:20177570

Senthilkumar, B; Dhavamani, V; Ramkumar, S; Philominathan, P

2010-01-01

118

Experiences with area specific spectrum stripping of NaI(Tl) gamma spectra.  

PubMed

Processing of airborne and carborne gamma-ray spectra (AGS and CGS) often includes the stripping (elimination) of the signals from natural radioactivity. Hereby the net result becomes the signals from man-made radioactivity or other radiation anomalies. The parameters needed for spectrum stripping are dependent on detector size and quality as well as on the energy windows. In addition they depend on the environmental geometry including the vehicle carrying the detector. For AGS the altitude also influences the parameters. In general the stripping parameters are determined from tedious laboratory or field measurements with known sources of natural radioactivity. Stripping parameters may, however, often be calculated from the actual survey data or from data from a similar area. Both post-processing and real-time processing are possible. The technique is useful for gamma source search, for detection of radiation anomalies and for mapping of contamination levels. The use of the technique is illustrated with field exercise data. PMID:16488919

Aage, H K; Korsbech, U; Bargholz, K; Bystöm, S; Wedmark, M; Thorshaug, S

2006-01-01

119

The Imprint of the Extragalactic Background Light in the Gamma-Ray Spectra of Blazars  

NASA Astrophysics Data System (ADS)

The light emitted by stars and accreting compact objects through the history of the universe is encoded in the intensity of the extragalactic background light (EBL). Knowledge of the EBL is important to understand the nature of star formation and galaxy evolution, but direct measurements of the EBL are limited by galactic and other foreground emissions. Here, we report an absorption feature seen in the combined spectra of a sample of gamma-ray blazars out to a redshift of z ˜ 1.6. This feature is caused by attenuation of gamma rays by the EBL at optical to ultraviolet frequencies and allowed us to measure the EBL flux density in this frequency band.

Ackermann, M.; Ajello, M.; Allafort, A.; Schady, P.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Bottacini, E.; Bouvier, A.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chaves, R. C. G.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; D'Ammando, F.; de Palma, F.; Dermer, C. D.; Digel, S. W.; do Couto e Silva, E.; Domínguez, A.; Drell, P. S.; Drlica-Wagner, A.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grove, J. E.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Hayashida, M.; Hays, E.; Jackson, M. S.; Jogler, T.; Kataoka, J.; Knödlseder, J.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Mazziotta, M. N.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Mizuno, T.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Tramacere, A.; Nuss, E.; Greiner, J.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reyes, L. C.; Ritz, S.; Rau, A.; Romoli, C.; Roth, M.; Sánchez-Conde, M.; Sanchez, D. A.; Scargle, J. D.; Sgrò, C.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Stawarz, ?ukasz; Suson, D. J.; Takahashi, H.; Tanaka, T.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Waite, A. P.; Winer, B. L.; Wood, K. S.; Wood, M.

2012-11-01

120

Expected gamma-ray emission spectra from the lunar surface as a function of chemical composition  

NASA Technical Reports Server (NTRS)

The gamma rays emitted from the moon or any similar body carry information on the chemical composition of the surface layer. The elements most easily measured are K, U, Th and major elements such as O, Si, Mg, and Fe. The expected fluxes of gamma ray lines were calculated for four lunar compositions and one chondritic chemistry from a consideration of the important emission mechanisms: natural radioactivity, inelastic scatter, neutron capture, and induced radioactivity. The models used for cosmic ray interactions were those of Reedy and Arnold and Lingenfelter. The areal resolution of the experiment was calculated to be around 70 to 140 km under the conditions of the Apollo 15 and 16 experiments. Finally, a method was described for recovering the chemical information from the observed scintillation spectra obtained in these experiments.

Reedy, R. C.; Arnold, J. R.; Trombka, J. I.

1973-01-01

121

The probability of detecting absorption features in gamma-ray burst spectra  

NASA Technical Reports Server (NTRS)

It has recently been suggested that several mechanisms for the primary release of energy in gamma-ray bursts may result in the excitation of magnetospheric plasma oscillations (MPO) above the polar cap of a neutron star. The basic MPO idea is refined by determining the soft photon source (which damps the particle motion via inverse Compton scattering interactions) self-consistently by means of a Monte Carlo simulation for the deposition of back-scattered gamma-ray energy below the stellar photosphere. The observed fraction of bursts displaying low-energy absorption features may be understood in the context of a model wherein the overall spectrum changes with inclination angle due to the superposition of several components with different angular distributions. GRB spectra should display these cyclotron lines about 18 percent of the time, which is consistent with the KONUS and Ginga sets of data.

Melia, F.

1989-01-01

122

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

123

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

124

Calibration of an air monitor prototype for a radiation surveillance network based on gamma spectrometry.  

PubMed

The objective of this work is to present the improvements that have been made in quasi-real-time air radioactivity concentration monitors which were initially based on overall activity determinations, by incorporating gamma spectrometry into the current prototype. To this end it was necessary to develop a careful efficiency calibration procedure for both the particulate and the gaseous fractions of the air being sampled. The work also reports the values of the minimum detectable activity calculated for different isotopes and acquisition times. PMID:24355305

Baeza, A; Caballero, J M; Corbacho, J Á; Ontalba-Salamanca, M Á; Vasco, J

2014-05-01

125

Low Background Gamma-Ray Spectrometry in the 'Laboratoire Souterrain de Modane'  

SciTech Connect

Most of the underground experiments in physics and many studies in geology, biology or environmental sciences face a common requirement with the necessity of using experimental devices with ultra-low background radioactivity. Many developments involving many different techniques have been used in order to be able to measure extremely low levels of radioactivity in materials. This report will focus on low background gamma-ray spectrometry and will describe the work which has been carried out over the last fifteen years in the 'Laboratoire Souterrain de Modane' (LSM)

Hubert, Ph.; Hubert, F. [Centre d'Etudes Nucleaires de Bordeaux Gradignan, BP 120, Le Haut Vigneau, 33175 Gradignan Cedex (France)

2007-03-28

126

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

127

Precipitation correction of airborne gamma-ray spectrometry data using monitoring profiles: methodology and case study  

NASA Astrophysics Data System (ADS)

Variations of soil moisture content caused by precipitation often complicate the interpretation of airborne gamma-ray spectrometry data. This is particularly the case in repeated surveys designed to monitor the change of near surface abundances of radioactive elements or in large and time-consuming surveys. To counter this precipitation effect we propose a correction method based on repeated survey flights over a monitoring profile. Assuming that the weather and the soil conditions at the monitoring profile are representative for the survey area, the weather dependent effect of soil moisture can be observed and sufficiently corrected.

Ahl, Andreas; Motschka, Klaus; Slapansky, Peter

2014-08-01

128

Comparison of digital signal processing modules in gamma-ray spectrometry.  

PubMed

Commercial digital signal-processing modules have been tested for their applicability to gamma-ray spectrometry. The tests were based on the same n-type high purity germanium detector. The spectrum quality was studied in terms of energy resolution and peak area versus shaping parameters, using a Eu-152 point source. The stability of a reference peak count rate versus the total count rate was also examined. The reliability of the quantitative results is discussed for their use in measurement at the metrological level. PMID:24315086

Lépy, Marie-Christine; Cissé, Ousmane Ibrahima; Pierre, Sylvie

2014-05-01

129

Monte Carlo simulation by GEANT 4 and GESPECOR of in situ gamma-ray spectrometry measurements.  

PubMed

The application of GEANT 4 and GESPECOR Monte Carlo simulation codes for efficiency calibration of in situ gamma-ray spectrometry was studied. The long computing time required by GEANT 4 prevents its use in routine simulations. Due to the application of variance reduction techniques, GESPECOR is much faster. In this code specific procedures for incorporating the depth profile of the activity were implemented. In addition procedures for evaluating the effect of non-homogeneity of the source were developed. The code was validated by comparison with test simulations carried out with GEANT 4 and by comparison with published results. PMID:23566809

Chirosca, Alecsandru; Suvaila, Rares; Sima, Octavian

2013-11-01

130

Development and calibration of a real-time airborne radioactivity monitor using direct gamma-ray spectrometry with two scintillation detectors.  

PubMed

The implementation of in-situ gamma-ray spectrometry in an automatic real-time environmental radiation surveillance network can help to identify and characterize abnormal radioactivity increases quickly. For this reason, a Real-time Airborne Radioactivity Monitor using direct gamma-ray spectrometry with two scintillation detectors (RARM-D2) was developed. The two scintillation detectors in the RARM-D2 are strategically shielded with Pb to permit the separate measurement of the airborne isotopes with respect to the deposited isotopes.In this paper, we describe the main aspects of the development and calibration of the RARM-D2 when using NaI(Tl) or LaBr3(Ce) detectors. The calibration of the monitor was performed experimentally with the exception of the efficiency curve, which was set using Monte Carlo (MC) simulations with the EGS5 code system. Prior to setting the efficiency curve, the effect of the radioactive source term size on the efficiency calculations was studied for the gamma-rays from (137)Cs. Finally, to study the measurement capabilities of the RARM-D2, the minimum detectable activity concentrations for (131)I and (137)Cs were calculated for typical spectra at different integration times. PMID:24607535

Casanovas, R; Morant, J J; Salvadó, M

2014-07-01

131

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

132

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

SciTech Connect

A technique has been developed for the measurement of /sup 228/Ra and /sup 226/Ra 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 BaSO/sub 4/. Lower limits of detection are controlled by the volume of water processed through the Mn fibers. In a 1-day count, samples as low as 10 dpm are measured to +-10% uncertainty. This Mn-fiber-..gamma..-ray technique is shown to be more accurate than the /sup 228/Ac methods recommended by the Environmental Protection Agency and as accurate but more rapid than the /sup 228/Th-Ingrowth procedure.

Michel, J.; Moore, W.S.; King, P.T.

1981-10-01

133

BATSE observations of gamma-ray burst spectra. I - Spectral diversity  

NASA Technical Reports Server (NTRS)

We studied the time-averaged gamma-ray burst spectra accumulated by the spectroscopy detectors of the Burst and Transient Source Experiment. The spectra are described well at low energy by a power-law continuum with an exponential cutoff and by a steeper power law at high energy. However, the spectral parameters vary from burst to burst with no universal values. The break in the spectrum ranges from below 100 keV to more than 1 MeV, but peaks below 200 keV with only a small fraction of the spectra breaking above 400 keV; it is therefore unlikely that a majority of the burst spectra are shaped directly by pair processes, unless bursts originate from a broad redshift range. The correlations among burst parameters do not fulfill the predictions of the cosmological models of burst origin. No correlations with burst morphology or the spatial distribution were found. We demonstrate the importance of using a complete spectral description even if a partial description (e.g., a model without a high-energy tail) is statistically satisfactory.

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

1993-01-01

134

The Gamma-Ray Spectra of Supernova Remnants Arising from SNe of Various Types  

NASA Astrophysics Data System (ADS)

Supernovae (SNe) are generally classified into Type I and Type II. Most SNe, including all those of Type II and Ib/c, arise from the core-collapse of massive stars. During their lifetime, mass-loss from these stars considerably modifies the medium around the stars. When the stars explode as SNe, the resulting shock wave will expand in this wind-modified medium, and the gamma-ray spectra are due to particle acceleration in this medium. In contrast, Type Ia SNe will expand in a relatively uniform medium, but the dynamics are different from those of core-collapse SNe. In this work we compute the spectra of accelerated particles, and the surface brightness distribution at very high energies, for SNRs of various types. We use high-resolution numerical simulations to study the expansion of the SN shock wave in the complicated medium; consider transport of frozen-in magnetic field by the plasma flow within the remnant; calculate cosmic-ray acceleration by solving the cosmic-ray transport equation in the test particle limit; include contributions from both forward and reverse shocks; and trace escaped particles out to about 50 SNR radii. We find that the complex environment, the reverse shock, and plasma-flow profiles all contribute to shaping the particle spectra. Our results show softer spectra for young supernova remnants that are consistent with recent results from Fermi and ground-based telescope arrays.

Dwarkadas, Vikram; Telezhinsky, I.; Pohl, M.

2013-04-01

135

Gamma-ray spectra of hexane (C6H14) in positron–electron annihilation process  

NASA Astrophysics Data System (ADS)

Theoretical gamma-ray spectra of molecule hexane have been calculated and compared with the experimental results in both gas (Iwata et al., 1997a) and liquid (Kerr et al., 1965) phases. The present study reveals that in gas phase not all valence electrons of hexane contribute the same degree in the electron–positron annihilation of hexane. The electrons which dominate the positron–electron annihilation of molecules are called positrophilic electrons. The positrophilic electrons are predominately found to involve the electrons on the lowest occupied valence orbital (LOVO) of a free molecule in gas phase. When hexane is confined in liquid phase, however, the intermolecular interactions ultimately eliminate the free molecular orientation and selectivity for the positrophilic electrons in the gas phase. As a result, the gamma-ray spectra of hexane become an "averaged" contribution from all valence electrons, which is again in agreement with liquid phase measurement. The roles of valence electrons in annihilation process for gas and liquid phases of hexane have been recognized for the first time in the present study.

Ma, Xiaoguang; Wang, Feng

2013-08-01

136

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

137

The signature of the cosmological redshift in population studies of gamma-ray burst spectra  

NASA Technical Reports Server (NTRS)

The slope of a gamma-ray burst spectrum determines how the burst flux decreases as the cosmological redshift z increases. This provides a test for the presence of a cosmological redshift in a sample of gamma-ray bursts. Many bursts have spectra characterized by a frequency-dependent power-law index, so a burst subset can be created by requiring that each subset member have a power-law index of the given value at a low frequency and an index of a different given value at a high frequency. If all bursts in this subset are at z much less than 0.1, then the flux at low frequency will change proportionally with the flux at high frequency. If, however, z greater than 0.1 for most bursts, then the linear dependence of the high-frequency flux on the low-frequency flux disappears at the flux characterizing the spatial cutoff in the log N-log C(max)/C(min) diagram. This signature of the cosmological redshift generally persists when gamma-ray bursts are given a broad distribution of intrinsic fluxes and spectral shapes. The characteristics that a burst distribution must have to mask the cosmological redshift are discussed. The limitations of this test are observational, arising primarily from errors in measuring the photon flux and in determining the spectral index of the burst spectrum.

Brainerd, J. J.

1993-01-01

138

Modeling Gamma-Ray Attenuation in High Redshift GeV Spectra  

NASA Astrophysics Data System (ADS)

We present two models for the cosmological UV background light, and calculate the opacity of GeV gamma-rays out to redshift 9. The contributors to the background include 2 possible quasar emissivities, and output from star-forming galaxies as determined by recent a semi-analytic model (SAM) of structure formation. The SAM used in this work is based upon a hierarchical build-up of structure in a ?CDM universe and is highly successful in reproducing a variety of observational parameters. Above 1 Rydberg energy, ionizing radiation is subject to reprocessing by the IGM, which we treat using our radiative transfer code, CUBA. The two models for quasar emissivity differing above z = 2.3 are chosen to match the ionization rates observed using flux decrement analysis and the higher values of the line-of-sight proximity effect. We also investigate the possibility of aflat star formation rate density at z>5. We conclude that observations of gamma-rays from 10 to 100 GeV by Fermi (GLAST) and the next generation of ground based experiments should confirm a strongly evolving opacity from 1spectra of gamma-ray bursts at higher redshift could constrain emission of UV radiation at these early times, either from a flat or increasing star-formation density or an unobserved population of sources.

Gilmore, Rudy C.; Madau, Piero; Primack, Joel R.; Somerville, Rachel S.

2008-12-01

139

Identification and Quantification of Plutonium and Uranium from Fission Product Gamma-Ray Spectra.  

NASA Astrophysics Data System (ADS)

A technique has been developed to distinguish between ^{239}Pu and ^{235}U by observing fission product delayed gamma-rays produced by fissions induced by an external neutron source. If the number of induced fissions per source neutron per unit mass can be determined from Monte Carlo simulation, the material can also be quantified. Trials were performed with yellowcake, HEU-metal, and Pu-metal samples using a TRIGA reactor and a large ^{252}Cf source as neutron sources. Fission product gamma-ray spectra were collected using a high-resolution hpGe detector over time intervals ranging from 60 s to 3000 s following the end of irradiation. By virtue of being greatly overdetermined, the identity of the Special Nuclear Material (SNM) can be unambiguously determined with a high degree of confidence in all cases by applying a set of Figure of Merit functions. Identification can be made without regard to the properties of the matrix provided a sufficient number of fissions can be induced within the sample to permit observation of the fission product gamma-rays. Once identified, the SNM can be quantified with an accuracy determined mainly by the ability to accurately model the fission response of the system using Monte Carlo simulation, within 3.8 percent in this study.

Beddingfield, David Harris

140

EPR spectra induced by gamma-irradiation of some dry medical herbs  

NASA Astrophysics Data System (ADS)

The radiation-induced EPR spectra in some medical herbs are reported. The samples studied are: (i) leaves of nettle, common balm, peppermint and thyme; (ii) stalks of common balm, thyme, milfoil, yarrow and marigold; (iii) blossoms of yarrow and marigold; (iv) blossoms and leaves of hawthorn and tutsan; and (v) roots of common valerian, nettle, elecampane (black and white), restharrows and carlina. Before irradiation all samples exhibit one weak anisotropic singlet EPR line with effective g-value of 2.0050±0.0002. The radiation-induced spectra fall into three groups. EPR spectra of irradiated blossoms of yarrow and marigold, stalks of common balm, thyme, tutsan and yarrow as well as roots of common valerian, nettle and elecampane (black and white) show "cellulose-like" EPR spectrum typical for irradiated plants. It is characterized by one intense central line with g=2.0050±0.0005 and two weak satellite lines situated ca. 30 G left and right to it. EPR spectra of gamma-irradiated restharrows and carlina are complex. They may be represented by one triplet corresponding to the "cellulose-like" EPR spectrum, one relatively intense singlet, situated in the center of the spectrum, and five weak additional satellite lines left and right to the center. The last spectrum was assigned as "carbohydrate-like" type. Only one intense EPR singlet with g=2.0048±0.0005 was recorded after irradiation of leaves of nettle and common balm. The lifetime of the radiation-induced EPR spectra was followed for a period of 3 months.

Yordanov, N. D.; Lagunov, O.; Dimov, K.

2009-04-01

141

Application of blind source separation to gamma ray spectra acquired by GRaND around Vesta  

NASA Astrophysics Data System (ADS)

The bismuth germinate (BGO) scintillator is one of the sensors of the gamma ray and neutron detector (GRaND)1 on board the Dawn spacecraft, that has spent just over one year in orbit around the asteroid 4-Vesta. The BGO detector is excited by energetic gamma-rays produced by galactic cosmic rays (GCR) or energetic solar particles interacting either with Vesta and/or the Dawn spacecraft. In detail, during periods of quiet solar activity, gamma ray spectra produced by the scintillator can be considered as consisting of three signals: i) a contribution of gamma-rays from Vesta produced by GCR interactions at the asteroid's surface, ii) a contribution from the spacecraft excited by neutrons coming from Vesta, and iii) a contribution of the spacecraft excited by local interaction with galactic cosmic rays. While the first two contributions should be positive functions of the solid angle of Vesta in the field of view during acquisition, the last one should have a negative dependence because Vesta partly shields the spacecraft from GCR. This theoretical mix can be written formally as: S=a?SV+b?SSCNV+c(4?-?)SSCGCR (1) where S is the series of recorded spectra, ? is the solid angle, SV is the contribution of gamma rays coming from Vesta, SSCNV is the contribution of gamma rays coming from the spacecraft excited by the neutron coming from Vesta and SSCGCR is the contribution of gamma rays coming from the spacecraft excited by GCR. A blind source separation method called independent component analysis enables separating additive subcomponents supposing the mutual statistical independence of the non-Gaussian source signals2. Applying this method to BGO spectra acquired during the first three months of the low-altitude measurement orbit (LAMO) reveals two main independent components. The first one is dominated by the positron electron annihilation peak and is positively correlated to the solid angle. The second is negatively correlated to the solid angle and displays peaks of elements present in the spacecraft, of energy in the range 1 to 3.5 MeV. At energy >3.5 MeV, the dominant independent component highlighted by this method has no significant peaks, suggesting that it is not influenced by Vesta itself which is known to have a strong signal associated with iron at 7.6 MeV. Our method therefore represents a first step in retrieving the contribution of the spacecraft that could be used in conjunction with the mixing equation (1) to determine the contribution from the planet itself. 1 : Prettyman, T. H., Mcsween, Jr., H. Y., Feldman, W. C., JUN 2010. Dawn's GRaND to map the chemical composition of asteroids Vesta and Ceres. Geochimica and Cosmochimica Acta 74 (12, 1), A832, Con- ference on Goldschmidt 2010 - Earth, Energy, and the Environment, Knoxville, TN, JUN 13-18, 2010. 2 : Hyvarinen, A., Oja, E., May-Jun 2000. Independent component analysis: algorithms and applications. Neural Networks 13 (4-5), 411-430.

Mizzon, H.; Toplis, M. J.; Forni, O.; Prettyman, T. H.; Raymond, C. A.; Russell, C. T.

2012-12-01

142

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

143

Photon and neutrino spectra of time-dependent photospheric models of gamma-ray bursts  

NASA Astrophysics Data System (ADS)

Thermal photons from the photosphere may be the primary source of the observed prompt emission of gamma-ray bursts (GRBs). In order to produce the observed non-thermal spectra, some kind of dissipation mechanism near the photosphere is required. In this paper we numerically simulate the evolution of the photon spectrum in a relativistically expanding shell with a time-dependent numerical code. We consider two basic models. One is a leptonic model, where a dissipation mechanism heats the thermal electrons maintaining their high temperature. The other model involves a cascade process induced by pp(pn)-collisions which produce high-energy electrons, modify the thermal spectrum, and emit neutrinos. The qualitative properties of the photon spectra are mainly determined by the optical depth at which the dissipation mechanism sets in. Too large optical depths lead to a broad and curved spectrum contradicting the observations, while for optical depths smaller than unity the spectral hardness becomes softer than observed. A significant shift of the spectral peak energy to higher energies due to a large energy injection can lead to an overly broad spectral shape. We show ideal parameter ranges for which these models are able to reproduce the observed spectra. For the pn-collision model, the neutrino fluence in the 10-100 GeV range is well above the atmospheric neutrino fluence, but its detection is challenging for presently available detectors.

Asano, K.; Mészáros, P.

2013-09-01

144

Absorption spectra of gamma-irradiation TM-doped cabal glasses  

NASA Astrophysics Data System (ADS)

The UV-visible absorption spectra of nominally pure and transition metals-doped (Ti ? Cu 0.1%) cabal glasses were measured from 200 to 1000 nm before and after successive gamma irradiation. The absorption spectra of the undoped glass exhibit charge transfer bands due to iron trace impurities which eventually affect the induced absorption due to some transition metals and that due to the host base glass in the UV region. The intensity of the radiation-induced bands depends on the number of intrinsic defects and the rate of formation of the different induced color centers. Also, the possible photochemical processes due to the effect of radiation on the transition metal ions are observed to affect the overall induced spectra. The growth behavior of the repetitive induced bands in the undoped and TM-doped glasses reveals a fast increase at first dose and the growth rate decreases or approaches saturation afterwards and different possible assumptions are given to interpret this behavior.

Marzouk, Samir Y.; Elbatal, Fatma H.; Salem, A. M.; Abo-Naf, S. M.

2007-07-01

145

The 124Sb activity standardization by gamma spectrometry for medical applications  

NASA Astrophysics Data System (ADS)

This work describes a metrological activity determination of 124Sb, which can be used as radiotracer, applying gamma spectrometry methods with hyper pure germanium detector and efficiency curves. This isotope with good activity and high radionuclidic purity is employed in the form of meglumine antimoniate (Glucantime) or sodium stibogluconate (Pentostam) to treat leishmaniasis. 124Sb is also applied in animal organ distribution studies to solve some questions in pharmacology. 124Sb decays by ?-emission and it produces several photons (X and gamma rays) with energy varying from 27 to 2700 keV. Efficiency curves to measure point 124Sb solid sources were obtained from a 166mHo standard that is a multi-gamma reference source. These curves depend on radiation energy, sample geometry, photon attenuation, dead time and sample-detector position. Results for activity determination of 124Sb samples using efficiency curves and a high purity coaxial germanium detector were consistent in different counting geometries. Also uncertainties of about 2% ( k=2) were obtained.

de Almeida, M. C. M.; Iwahara, A.; Delgado, J. U.; Poledna, R.; da Silva, R. L.

2010-07-01

146

Nondestructive characterization of radioactive waste drums by gamma spectrometry: a Monte Carlo technique for efficiency calibration.  

PubMed

A semi-empirical non-destructive technique to assay radioactive waste drums is presented. The technique is based on gamma spectrometry performed using a portable NaI detector and Monte Carlo simulations using the MCNP code in order to derive the gamma ray detector efficiency for the volume source. The derivation of detector efficiency was performed assuming homogeneous distribution of the source activity within the matrix material. Moreover, the MCNP model was used to examine the effect of inhomogeneities in activity distribution, variation of matrix material density, and drum filling height on the accuracy of the technique, and to estimate the measurement bias. The technique was verified by estimating radioactivity levels in 25 drums containing ion exchange resin waste, and comparing the results of the non-destructive method against the analytical results of samples obtained from each drum. Satisfactory agreement between the two assay techniques was observed. The discussed technique represents a cost effective technology that can be used to assay low-activity, low-density waste drums provided the contribution to the gamma ray spectrum can be resolved. PMID:18049246

Tzika, Faidra; Savidou, Anastasia; Stamatelatos, Ion E

2007-11-01

147

Cosmic veto gamma-spectrometry for Comprehensive Nuclear-Test-Ban Treaty samples  

NASA Astrophysics Data System (ADS)

The Comprehensive Nuclear-Test-Ban Treaty (CTBT) is supported by a global network of monitoring stations that perform high-resolution gamma-spectrometry on air filter samples for the identification of 85 radionuclides. At the UK CTBT Radionuclide Laboratory (GBL15), a novel cosmic veto gamma-spectrometer has been developed to improve the sensitivity of station measurements, providing a mean background reduction of 80.8% with mean MDA improvements of 45.6%. The CTBT laboratory requirement for a 140Ba MDA is achievable after 1.5 days counting compared to 5-7 days using conventional systems. The system consists of plastic scintillation plates that detect coincident cosmic-ray interactions within an HPGe gamma-spectrometer using the Canberra LynxTM multi-channel analyser. The detector is remotely configurable using a TCP/IP interface and requires no dedicated coincidence electronics. It would be especially useful in preventing false-positives at remote station locations (e.g. Halley, Antarctica) where sample transfer to certified laboratories is logistically difficult. The improved sensitivity has been demonstrated for a CTBT air filter sample collected after the Fukushima incident.

Burnett, J. L.; Davies, A. V.

2014-05-01

148

EMISSION FROM HOT DUST IN THE INFRARED SPECTRA OF GAMMA-RAY BRIGHT BLAZARS  

SciTech Connect

A possible source of {gamma}-ray photons observed from the jets of blazars is inverse Compton scattering by relativistic electrons of infrared seed photons from a hot, dusty torus in the nucleus. We use observations from the Spitzer Space Telescope to search for signatures of such dust in the infrared spectra of four {gamma}-ray bright blazars, the quasars 4C 21.35, CTA102, and PKS 1510-089, and the BL Lacertae object ON231. The spectral energy distribution (SED) of 4C 21.35 contains a prominent infrared excess indicative of dust emission. After subtracting a non-thermal component with a power-law spectrum, we fit a dust model to the residual SED. The model consists of a blackbody with temperature {approx}1200 K, plus a much weaker optically thin component at {approx}660 K. The total luminosity of the thermal dust emission is 7.9 {+-} 0.2 x 10{sup 45} erg s{sup -1}. If the dust lies in an equatorial torus, the density of infrared photons from the torus is sufficient to explain the {gamma}-ray flux from 4C 21.35 as long as the scattering occurs within a few parsecs of the central engine. We also report a tentative detection of dust in the quasar CTA102, in which the luminosity of the infrared excess is 7 {+-} 2 x 10{sup 45} erg s{sup -1}. However, in CTA102 the far-infrared spectra are too noisy to detect the 10 {mu}m silicate feature. Upper limits to the luminosity from thermal emission from dust in PKS 1510-089, and ON231, are 2.3 x 10{sup 45}, and 6.6 x 10{sup 43} erg s{sup -1}, respectively. These upper limits do not rule out the possibility of inverse Compton upscattering of infrared photons to {gamma}-ray energies in these two sources. The estimated covering factor of the hot dust in 4C 21.35, 22%, is similar to that of non-blazar quasars; however, 4C 21.35 is deficient in cooler dust.

Malmrose, Michael P.; Marscher, Alan P.; Jorstad, Svetlana G. [Institute for Astrophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States); Nikutta, Robert; Elitzur, Moshe [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506-0055 (United States)

2011-05-10

149

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

150

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

Microsoft Academic Search

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

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

2009-01-01

151

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

152

An iterative approach for TRIGA fuel burn-up determination using nondestructive gamma-ray spectrometry.  

PubMed

The purpose of this work is to establish a method for evaluating the burn-up values of the rod-type TRIGA spent fuel by using gamma-ray spectrometry of the short-lived fission products 97Zr/97Nb, 132I, and 140La. Fuel irradiation history is not needed in this method. Short-lived fission-product activities were established by reirradiating the spent fuels in a nuclear reactor. Based on the measured activities, 235U burn-up values can be deduced by iterative calculations. The complication caused by 239Pu production and fission is also discussed in detail. The burn-up values obtained by this method are in good agreement with those deduced from the conventional method based on long-lived fission products 137Cs, 134Cs/137Cs ratio and 106Ru/137Cs ratio. PMID:10670930

Wang, T K; Peir, J J

2000-01-01

153

Initial recommendations for restricting gamma-ray spectrometry measurements of radionuclides for on-site inspections  

Microsoft Academic Search

The US paper �Radionuclide Sampling, Sample Handling and Analytical Laboratory Equipment for Comprehensive Test Ban Treaty On-Site Inspections,� CTBT\\/PC\\/V\\/OSI\\/WSII\\/PR\\/29 identified the radionuclides of interest to an OS1 as 144<\\/sup>Ce, 147<\\/sup>Nd, 141<\\/sup>Ce, 149<\\/sup>Ba140<\\/sup>La), 95<\\/sup> Zr(95<\\/sup>Nb), 131m<\\/sup>Xe, 133m<\\/sup>Xe, 133g<\\/sup>Xe, 135g<\\/sup>Xe, and 37<\\/sup>Ar. All of these nuclides (except 37<\\/sup>Ar) can be measured via some form of conventional or coincidence-based gamma-ray spectrometry. The non-gaseous

W. F. Buckley; S. A. Kreek; J. F. Wild

1998-01-01

154

Summary of gamma spectrometry on local air samples from 1985--1995  

SciTech Connect

This report summarizes the 1985--1995 results of low-level HPGe gamma spectrometry analysis of high-volume air samples collected at the Aiken Airport, which is about 25 miles north of SRS. The author began analyzing these samples with new calibrations using the newly developed GRABGAM code in 1985. The air sample collections were terminated in 1995, as the facilities at the Aiken Airport were no longer available. Air sample measurements prior to 1985 were conducted with a different analysis system (and by others prior to 1984), and the data were not readily available. The report serves to closeout this phase of local NTS air sample studies, while documenting the capabilities and accomplishments. Hopefully, the information will guide other applications for this technology, both locally and elsewhere.

Winn, W.G.

1997-04-02

155

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

156

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

157

Isotopic Identification of Neutron Resonances of Cd, Sb, Os, and Pt from Capture Gamma-Ray Spectra  

Microsoft Academic Search

The Argonne fast chopper has been used in conjunction with a 3-variable magnetic-tape recording system to demonstrate the high efficiency and sensitivity of isotopic identification of neutron resonances by observation of capture gamma rays. A discussion of features of capture spectra which can be useful in isotopic assignment is presented as well as results for resonances in natural Cd, Sb,

H. E. Jackson; L. M. Bollinger

1961-01-01

158

A Concept for the Measurement of Gamma-Ray Spectra from Pulsed Reactors or Flash X-Ray Machines.  

National Technical Information Service (NTIS)

The report describes a concept for the measurement of gamma-ray spectra using fixed-energy variable-angle Compton electrons. The choice of a single electron energy eliminates variations in detector response and it can also eliminate the need for variation...

W. R. Van Antwerp

1970-01-01

159

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

160

BATSE observations of gamma-ray burst spectra. 2: Peak energy evolution in bright, long bursts  

NASA Technical Reports Server (NTRS)

We investigate spectral evolution in 37 bright, long gamma-ray bursts observed with the Burst and Transient Source Experiment (BATSE) spectroscopy detectors. High-resolution spectra are chracterized by the energy of the peak of nu F(sub nu), and the evolution of this quantity is examined relative to the emission intensity. In most cases it is found that this peak energy either rises with or slightly precedes major intensity increases and softens for the remainder of the pulse. Interpulse emission is generally harder early in the burst. For bursts with multiple intensity pulses, later spikes tend to be softer than earlier ones, indicating that the energy of the peak of nu F(sub nu) is bounded by an envelope which decays with time. Evidence is found that bursts in which the bulk of the flux comes well after the event which triggers the instrument tend to show less peak energy variability and are not as hard as several bursts in which the emission occurs promptly after the trigger. Several recently proposed burst models are examined in light of these results and no qualitative conflicts with the observations presented here are found.

Ford, L. A.; Band, D. L.; Matteson, J. L.; Briggs, M. S.; Pendleton, G. N.; Preece, R. D.; Paciesas, W. S.; Teegarden, B. J.; Palmer, D. M.; Schaefer, B. E.

1995-01-01

161

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

162

Power Density Spectra of Gamma-Ray Burst Light Curves: Implications on Theory and Observation  

NASA Astrophysics Data System (ADS)

We investigate statistical properties of gamma-ray burst (GRB) light curves by comparing the reported characteristics in the power density spectra (PDSs) of the observed GRBs with those that we model and discuss implications on interpretations of the PDS analysis results. Results of PDS analysis of observed GRBs suggest that the averaged PDS of GRBs follows a power law over about two decades of frequency with the power-law index, -5/3, and the distribution of individual power follows an exponential distribution. Although an attempt to identify the most sensitive physical parameter has been made on the basis of the internal shock model, we demonstrate that conclusions of this kind of approach should be derived with due care. We show that the reported slope and the distribution can be reproduced by adjusting the sampling interval in the time domain for a given decaying timescale of individual pulse in a specific form of GRB light curve. In particular, given that the temporal feature is modeled by a two-sided exponential function, the power-law behavior with the index of -5/3 and the exponential distribution of the observed PDS is recovered at the 64 ms trigger timescale when the decaying timescale of individual pulses is ~1 s, provided that the pulse sharply rises. Another way of using the PDS analysis is an application of the same method to individual long bursts in order to examine a possible evolution of the decaying timescale in a single burst.

Chang, Heon-Young; Yi, Insu

2000-10-01

163

Hydride formation and thermal desorption spectra of hydrogen of cathodically charged single-phase gamma titanium aluminide  

SciTech Connect

The authors have previously reported thermal desorption spectra of hydrogen obtained from cathodically charged two-phase (Ti{sub 3}Al ({alpha}{sub 2}) + TiAl ({gamma})) titanium aluminides by means of thermal desorption spectroscopy (TDS), in which hydrogen ion current (H{sub 2}{sup +}) corresponding to hydrogen evolution rate during heating was measured by a quadrupole mass spectrometer in an ultra-high vacuum condition. Several accelerated hydrogen evolutions (TDS peak temperatures) have been observed in a series of TDS measurement, and then the authors have suggested that these peaks were dependent on the microstructures ({alpha}{sub 2} and {gamma} phases) as well as dissociation of the hydride phase which formed during cathodic charging. A comparison with the TDS spectra from other series of titanium aluminides, such as a single-phase {gamma} alloy, might give clearer views of the microstructural dependence on hydrogen evolution kinetics. In this paper, hydride formation, hydrogen uptake and hydrogen evolution kinetic of a cathodically charged single-phase {gamma} titanium aluminide are investigated, and these results are compared with the previous ones obtained in two-phase ({alpha}{sub 2} + {gamma}) titanium aluminides.

Takasaki, Akito [Shibaura Inst. of Tech., Omiya, Saitama (Japan)] [Shibaura Inst. of Tech., Omiya, Saitama (Japan); Furuya, Yoshio [Nagasaki Univ. (Japan)] [Nagasaki Univ. (Japan)

1999-02-05

164

Application of low-background gamma-ray spectrometry to monitor radioactivity in the environment and food.  

PubMed

The results are described of an upgrade of the low-background gamma-ray spectrometry laboratory at New York State Department of Health by acquiring sensitivity to low-energy gamma rays. Tuning of the spectrometer and its low-energy response characteristics are described. The spectrometer has been applied to monitor the environment by measuring aerosols and water in New York State contaminated by the 2011 Fukushima accident plume. In addition, the spectrometer has been used to monitor radioactivity in food by performing a study of cesium in Florida milk. PMID:24836905

Khan, A J; Semkow, T M; Beach, S E; Haines, D K; Bradt, C J; Bari, A; Syed, U-F; Torres, M; Marrantino, J; Kitto, M E; Menia, T; Fielman, E

2014-08-01

165

Gamma-ray spectrometry of radon in water and the role of radon to representatively sample aquifers.  

PubMed

Measurement of radon in water by gamma-ray spectrometry using a HPGe detector has been investigated to determine aquifer characteristics. The radon activity concentration is determined by taking the weighted average of the concentrations derived from gamma-ray lines associated with (214)Pb and (214)Bi decay. The role of accurate radon data to representatively sample aquifers was also investigated by studying a semi-cased borehole. A simplified physical model describing the change of radon concentration with the pumping time, reproduces the data and predicts the time for representative sampling of the aquifer. PMID:18515121

Talha, S A; Lindsay, R; Newman, R T; de Meijer, R J; Maleka, P P; Hlatshwayo, I N; Mlwilo, N A; Mohanty, A K

2008-11-01

166

Method of Evaluating Quantities of Plutonium by Gamma Spectrometry Applied to Measurement of Retention Monitoring of Wastes and Surveillance of Facility Dismantling.  

National Technical Information Service (NTIS)

The gamma spectrometry method of measuring quantities of plutonium has now been developed in different fields of nuclear work to enable reliable balance management to be carried out, to ensure safety requirements are met and to make better discharge monit...

J. Morel B. Chauvenet M. Etcheverry J. Monier Y. Labernede

1987-01-01

167

Implementation of gamma-ray spectrometry in two real-time water monitors using NaI(Tl) scintillation detectors.  

PubMed

In this study, the implementation of gamma-ray spectrometry in two real-time water monitors using 2 in. × 2 in. NaI(Tl) scintillation detectors is described. These monitors collect the water from the river through a pump and it is analyzed in a vessel, which is shielded with Pb. The full calibration of the monitors was performed experimentally, except for the efficiency curve, which was set using validated Monte Carlo simulations with the EGS5 code system. After the calibration, the monitors permitted the identification and quantification of the involved isotopes in a possible radioactive increment and made it possible to discard possible leaks in the nuclear plants. As an example, a radiological increment during rain is used to show the advantages of gamma-ray spectrometry. To study the capabilities of the monitor, the minimum detectable activity concentrations for (131)I, (137)Cs and (40)K are presented for different integration times. PMID:23827508

Casanovas, R; Morant, J J; Salvadó, M

2013-10-01

168

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

PubMed

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 microSv y(-1)). PMID:9314225

Uyttenhove, J; Pommé, S; Van Waeyenberge, B; Hardeman, F; Buysse, J; Culot, J P

1997-10-01

169

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

Microsoft Academic Search

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

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

2010-01-01

170

sup 6\\/LiI(Eu) in neutron and \\/spl gamma\\/-ray spectrometry - a high sensitive thermal neutron detector  

Microsoft Academic Search

Europium activated 6LiI crystal (enriched to 96% 6Li) has been studied in neutron and gamma-ray spectrometry. Two crystals of Oslash50 mm times 5 mm and Oslash30 mm times 3 mm size coupled to a calibrated Photonis XP5200 photomultiplier were tested. A response of 6LiI(Eu) to neutrons emitted from a paraffin moderated Pu-Be source has been investigated and the thermal neutron

A. Syntfeld; M. Moszynski; R. Arlt; M. Balcerzyk; M. Kapusta; M. Majorov; R. Marcinkowski; P. Schotanus; M. Swoboda; D. Wolski

2004-01-01

171

Using gamma ray spectrometry for fingerprinting sources of estuarine and coastal sediment in Mukawa coast, Hokkaido, northern Japan  

NASA Astrophysics Data System (ADS)

To seek the geological tracers of environmental radionuclide for fingerprinting sources of estuarine and coastal sediment, the gamma ray spectrometry was conducted for the soil and sediment samples collected from subcatchments, rivers, estuaries and coast in Mukawa and Sarugawa river watersheds and Mukawa coast, Hokkaido, northern Japan. Gamma ray spectrometry was conducted to determine the activities of environmental radionuclides associated with each soil and sediment samples using HP Ge well-type detector. Gamma ray spectrometry could determine 15 environmental radionuclides, including U-series, Th-series, cesium-137 and potassium-40. Lead-210 excess was also determined by subtracting the activities of Pb-214 from that of Pb-210. The Kruskal-Wallis H test was conducted to assess the ability of each tracer property to discriminate between surface soil samples from the categories divided by subcatchment, geological era and period, suggesting that more than 11 tracer properties were available. Subsequently, the stepwise discriminant function analysis was conducted to identify which combination of tracer properties provides the best composite fingerprint for differentiating source materials on the basis of subcatchment and geology source groups. This analysis suggested that the composite fingerprints of Pb-212, Ac-228 and K-40 can classify the geology into 6 groups based on rock type. Using these tracer properties, the contribution of rock to estuarine and coastal sediment can be evaluated with the multivariate sediment mixing model.

Mizugaki, S.; Ohtsuka, J.; Murakami, Y.; Ishiya, T.; Hamamoto, S.

2010-12-01

172

Assessment of radiological hazards of Lawrencepur sand, Pakistan using gamma spectrometry.  

PubMed

The Lawrencepur sand had remained refrigerated during a long period of glaciations in the study area. Owing to its derivation from the granitic rocks of the Himalayas and its preservation under glacial environment, the sand grains are still fresh and may contain high level of primordial radioactivity. For that reason, radiological hazards of Lawrencepur sand were assessed using a high-purity germanium gamma spectrometry technique. The average activity concentrations of (226)Ra, (232)Th and (40)K were found to be 15.97±3.05, 27.98±4.89 and 498.20±15.91 Bq kg(-1), respectively. These values are higher than those of the sands of many countries of the world but lower than those of some of the Pakistani, Indian and Egyptian sands. The outdoor and indoor hazard indices and annual effective doses of the Lawrencepur sand are higher than those of some of the sand deposits of European, African and American countries but lower than those of nearby Pakistani and Indian sands. However, the hazard indices and annual effective doses of the Lawrencepur sand are within the safe limits. Overall, the Lawrencepur sand does not pose any radiological health hazard as a building material. PMID:23630384

Qureshi, Aziz Ahmed; Ali, Muhammad; Waheed, Abdul; Manzoor, Shahid; Siddique, Rehan Ul Haq; Ahmed Khan, Hameed

2013-11-01

173

Low-background gamma-ray spectrometry in the Garching underground laboratory  

NASA Astrophysics Data System (ADS)

We describe two setups that were built for low-background gamma-ray spectrometry in the Garching Underground Laboratory (~ 10 m.w.e.). Both setups are based on HPGe detectors surrounded by several layers of passive shielding as well as an active muon veto. The first setup (GEM) comprises a single HPGe detector surrounded by a NaI(Tl) scintillation detector that serves as anti-Compton veto. The second setup (LoAx) consists of two smaller HPGe detectors which are arranged face-to-face to cover a large solid angle around the sample. The detection efficiency of both systems is determined using a calibrated Monte-Carlo simulation. The count rate finally achieved in the energy range 40-2700keV is 10250+/-26cts/day for the GEM setup, and 5258+/-27cts/day and 6876+/-31cts/day between 20-1500keV for the two detectors of the LoAx setup. This leads to detection sensitivities of a few mBq/kg for U and Th at both screening stations.

Hofmann, M.; Mannel, T.; Sivers, M. V.

2013-08-01

174

Detection of /sup 210/Pb in the lungs of smokers by in-vivo gamma spectrometry  

SciTech Connect

Since mainstream smoke is highly enriched in /sup 210/Pb, alpha radiation from inhaled cigarette smoke particles has been proposed as a cancer-producing agent in cigarette smokers. /sup 210/Po and /sup 210/Pb have been observed in tobacco, cigarette smoke and in the lungs of smokers. Since /sup 210/Pb is highly enriched in mainstream smoke, there have been estimates of yearly excesses of /sup 210/Pb in the lungs of one-pack-a-day smokers of 3 to 10 pCi (0.11 to 0.37 Bq). The ORNL Whole Body Counter was used to verify this estimate by the methodology of high-resolution, in vivo gamma spectrometry. Measurements were made on 113 adult male non-radiation workers who have either smoked at least one pack of cigarettes per day for at least five years, or have never smoked cigarettes. An analysis-of-variance table was generated based on the Pb-ratio for each individual which revealed that there was no statistically significant increase in the amount of /sup 210/Pb in the lungs of smokers over those of non-smokers. Sources of error are also discussed.

Berger, C.D.; Lane, B.H.

1982-09-01

175

Performance of cerium-doped Gd3Al2Ga3O12 (GAGG:Ce) scintillator in gamma-ray spectrometry  

NASA Astrophysics Data System (ADS)

Performance of cerium-doped Gd3Al2Ga3O12 (GAGG:Ce) scintillator in gamma-ray spectrometry has been investigated. The measurements of two samples of GAGG:Ce cover the tests of emission spectra (maximum of emission at about 530 nm), light output, non-proportionality, energy resolution, time resolution and decay time of light pulses. We compare the results with commonly known scintillators, such as NaI(Tl), LSO, LuAG etc. The results show that GAGG:Ce has a high light yield of about 33000 ph/MeV as measured with Hamamatsu S3590-18 Si PiN photodiode [1]. The total energy resolution for 662 keV gamma-rays from 137Cs source is equal to about 6%, whereas intrinsic resolution is equal to 5.2%. Additionally, we made basic measurements of photoelectron yield, non-proportionality and total energy resolution of small sample (5×5×5 mm3) of GAGG:Ce crystal coupled to Hamamatsu MPPC array (6×6 mm2). The results show that the performance of GAGG:Ce measured with the MPPC array are similar to those measured with the PMT.

Iwanowska, Joanna; Swiderski, Lukasz; Szczesniak, Tomasz; Sibczynski, Pawel; Moszynski, Marek; Grodzicka, Martyna; Kamada, Kei; Tsutsumi, Kousuke; Usuki, Yoshiyuki; Yanagida, Takayuki; Yoshikawa, Akira

2013-06-01

176

Determination of Hafnium in Zirconium Standard Samples (JAERI-Z15,-Z16) by Neutron Activation and gamma-Ray Spectrometry of Sup(179M)Hf.  

National Technical Information Service (NTIS)

Trace amounts of hafnium in zirconium standard samples (JAERI-Z15,-Z16) were determined by neutron activation and gamma-ray spectrometry where 214.3 keV gamma-ray emitted from sup(179m)Hf (T sub(1/2) = 18.6 sec) are counted by a Ge(Li) detector. The zirco...

C. Yonezawa K. Takashima

1979-01-01

177

Gamma-Ray Spectra of Fission Products Observed with Lithium Drifted Germanium Detectors  

Microsoft Academic Search

The ?-ray spectra of fission products from thermal neutron irradiation of natural U were observed with an encapsulated Ii-drift-Ge ?-ray spectrometer. The spectra were recorded at various periods after irradiation—1, 2, 5, 12, 30, 250 days and 3 years. The ?-ray spectra of eight individual fission products including Np were also studied. Due to the high resolution obtained with the

Sei-ichi TAKAYANAGI; Noboru OI; Tetsuji KOBAYASHI; Tohru SUGITA

1966-01-01

178

Neutron-capture gamma-ray data for obtaining elemental abundances from planetary spectra.  

SciTech Connect

Determination of elemental abundances is a top scientific priority of most planetary missions. Gamma-ray spectroscopy is an excellent method to determine elemental abundances using gamma rays made by nuclear reactions induced by cosmic-ray particles and by the decay of radioactive nuclides [Re73,Re78]. Many important planetary gamma rays are made by neutron-capture reactions. However, much of the data for the energies and intensities of neutron-capture gamma rays in the existing literature [e.g. Lo81] are poor [RF99,RF00]. With gamma-ray spectrometers having recently returned data from Lunar Prospector and NEAR and soon to be launch to Mars, there is a need for good data for neutron-capture gamma rays.

Reedy, Robert; Frankle, S. C. (Stephanie C.)

2001-01-01

179

Gamma-ray burst spectra and time histories from 2 to 400 keV  

Microsoft Academic Search

The Gamma-Ray burst detector on Ginga consisted of a proportional counter to observe the x-rays and a scintillation counter to observe the gamma-rays. Both instrument recorded the time histories in phase with each other and with 0.03125 s temporal resolution. The author compares the average of 21 gamma-ray bursts to determine the delay, in any, between the peak of the

Fenimore

1998-01-01

180

Accurate gamma-ray spectrometry measurements of the half-life of 92Sr.  

PubMed

Studies of the nuclear fuel cycle require an accurate knowledge of the energy release from the decay of radioactive nuclides produced in a reactor, including precise half-life data for the short-lived radionuclides. Moreover, short-lived fission products are crucial for fission rate distribution measurements performed in low-power facilities, such as EOLE and MINERVE of CEA Cadarache [Fougeras, P., 2005. EOLE, MINERVE and MASURCA facilities and their associated neutron experimental programs. In: 13th International Conference on Nuclear Engineering, Beijing, China, 16-20 May 2005], and their nuclear decay data need to be known to high precision. For these reasons, the half-life of (92)Sr has been measured to solve a recently observed inconsistency identified with the quoted value in the main nuclear applications libraries (including JEFF3.1): T(1/2)=2.71+/-0.01 h [Parsa, B., Ashari, A., Goolvard, L., Nobar, Y.M., 1971. Decay scheme of 2.71 h (92)Sr. Nucl. Phys. A 175, 629-640]. An overestimation of 4.5% has been identified in this work, based on two independent methods. Specific gamma-ray spectrometry measurements on activated fissile foils have been carried out, using two HPGe detectors. Influencing factors such as net area measurements of photopeaks, pulse pile-up accuracy and dead time corrections in the presence of decaying activity are discussed. A new value has been obtained by combining eight series of measurements: T(1/2)=2.594+/-0.006 h. The uncertainty has been reduced by a factor of two with respect to previous evaluations. This measured value also shows good agreement with the most recent studies of T(1/2)=2.627+/-0.009 h [Nir-El, Y., 2003. Private Communications. Soreq Research Centre, Yavne, Israel]. PMID:18456504

Leconte, P; Hudelot, J P; Antony, M

2008-10-01

181

Neutron-Capture Gamma-Ray Data for Obtaining Elemental Abundances from Planetary Spectra  

NASA Astrophysics Data System (ADS)

Newly compiled and evaluated energies and intensities of gamma rays made by the capture of thermal neutrons by elements from H to Zn plus Ge, Sm, and Gd are reported for use in determining elemental composition by planetary gamma-ray spectroscopy.

Reedy, R. C.; Frankle, S. C.

2001-03-01

182

Gamma-ray burst spectra and time histories from 2 to 400 keV  

SciTech Connect

The Gamma-Ray burst detector on Ginga consisted of a proportional counter to observe the x-rays and a scintillation counter to observe the gamma-rays. Both instrument recorded the time histories in phase with each other and with 0.03125 s temporal resolution. The author compares the average of 21 gamma-ray bursts to determine the delay, in any, between the peak of the x-rays and the peak of the gamma-rays. The delay is less than or about equal to 30 msec. Thus, models must content with two average features of the temporal behavior. First, as a function of energy, the time structure scales as {approximately}E{sup {minus}0.45}. Second, the x-rays are not appreciable delayed relative to the gamma-rays. Some cooling models might have difficulties explaining these features.

Fenimore, E.E.

1998-07-01

183

Detection of in vitro kinase generated protein phosphorylation sites using gamma[18O4]-ATP and mass spectrometry.  

PubMed

A novel stable-isotope labeling approach for identification of phosphopeptides that utilizes adenosine triphosphate, in which four oxygen-16 atoms attached to the terminal phosphate group are substituted with oxygen-18 [gamma((18)O4)-ATP], has been developed. The ability to use gamma((18)O4)-ATP to monitor phosphorylation modification within various proteins was conducted by performing in vitro kinase reactions in the presence of a 1:1 mixture of gamma((18)O4)-ATP and normal isotopic abundance ATP (ATP). After tryptic digestion, the peptides were analyzed using mass spectrometry (MS). Phosphorylated peptides are easily recognized within the MS spectrum owing to the presence of doublets separated by 6.01 Da; representing versions of the peptide modified by ATP and gamma((18)O4)-ATP. Standard peptides phosphorylated using gamma((18)O4)-ATP via in vitro kinase reactions showed no exchange loss of (18)O with (16)O. The identity of these doublets as phosphorylated peptides could be readily confirmed using tandem MS. The method described here provides the first direct stable-isotope labeling method to definitely detect phosphorylation sites within proteins. PMID:17877366

Zhou, Ming; Meng, Zhaojing; Jobson, Andrew G; Pommier, Yves; Veenstra, Timothy D

2007-10-15

184

Use of an iterative convolution approach for qualitative and quantitative peak analysis in low resolution gamma-ray spectra  

NASA Astrophysics Data System (ADS)

In many applications, low resolution gamma-ray spectrometers, such as sodium iodide scintillation detectors, are widely used primarily due to their relatively low cost and high detection efficiency. There is widespread interest in improved methods for analyzing spectral data acquired with such devices, using inverse analysis. Peak means and peak areas in gamma- and X-ray spectra are needed for both qualitative and quantitative analysis. This paper introduces the PEAKSI code package that was developed at the Center for Engineering Applications of Radioisotopes (CEAR). The basic approach described here is to use accurate forward models and iterative convolution instead of direct deconvolution. Rather than smoothing and differentiation a combination of linear regression and non-linear searching is used to minimize the reduced chi-square, since this approach retains the capability of establishing uncertainties in the estimated peak parameters. The PEAKSI package uses a Levenberg-Marquardt (LM) non-linear search method combined with multiple linear regression (MLR) to minimize the reduced chi-square value for fitting single or multiple overlapping peaks to determine peak parameters, including peak means, peak standard deviations or full width at half maximum (FWHM), net peak counts, and background counts of peaks in experimental gamma-ray spectra. This approach maintains the natural error structure so that parameter uncertainties can be estimated. The plan is to release this code to the public in the near future.

Gardner, Robin P.; Ai, Xianyun; Peeples, Cody R.; Wang, Jiaxin; Lee, Kyoung; Peeples, Johanna L.; Calderon, Adan

2011-10-01

185

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

186

A new variant of the gamma subunit of renal Na,K-ATPase. Identification by mass spectrometry, antibody binding, and expression in cultured cells.  

PubMed

The gamma subunit is a specific regulator of Na,K-ATPase expressed mainly in kidney. On SDS-polyacryylamide gel electrophoresis, gamma runs as a doublet, but the origin and significance of the doublet is obscure. Mass spectrometry of the gamma chains of rat kidney Na, K-ATPase shows that gamma(a) (upper) has a mass of 7184.0 +/- 1 Da (carbamidomethyl cysteine), corresponding closely to that for the published sequence without the initiator methionine, while gamma(b) (lower) has a mass of 7337.9 +/- 1Da. Tryptic peptide mapping and sequencing by mass spectrometry reveals that the seven N-terminal residues of gamma(a), TELSANH, are replaced by Ac-MDRWYL in gamma(b), but otherwise the chains are identical. Antibodies raised against peptides TELSANHC and MDRWYLC recognize either gamma(a) or gamma(b) of the Na,K-ATPase, respectively. gamma(a) or gamma(b) cDNAs have been expressed in human embryonic kidney and HeLa cells. The major bands expressed correspond to gamma(a) or gamma(b) of renal Na, K-ATPase. Additional minor bands seen after transfection, namely gamma(a)' in human embryonic kidney and gamma(b)' in HeLa, are presumably cell-specific modifications. The present work clarifies earlier uncertainty regarding doublets seen in kidney and in transfected cells. In particular, the results show that renal Na, K-ATPase contains two variants of the gamma subunit with different sequences but otherwise are unmodified. We discuss the possible functional significance of the two variants. PMID:10748024

Kuster, B; Shainskaya, A; Pu, H X; Goldshleger, R; Blostein, R; Mann, M; Karlish, S J

2000-06-16

187

Calculated gamma-ray spectra for keV neutron capture in ²⁴°Pu, ²⁴²Pu, and ²³⁸U  

Microsoft Academic Search

Capture gamma-ray spectra of ²⁴°Pu, ²⁴²Pu, and ²³⁸U were calculated in the framework of the spherical optical model and the statistical model. A consistent set of input parameters was determined from available experimental information or from model-guided systematics. The complete gamma-ray cascades were calculated considering all possible transitions up to multiplicity seven. All experimental information on level schemes and gamma-ray

G. Reffo; F. Fabbri; F. Kappeler; K. Wisshak

1983-01-01

188

Methylation of gamma-carboxylated Glu (Gla) allows detection by liquid chromatography-mass spectrometry and the identification of Gla residues in the gamma-glutamyl carboxylase  

PubMed Central

Gamma-carboxylated Glu (Gla) is a post-translational modification required for the activity of vitamin K-dependent (VKD) proteins that has been difficult to study by mass spectrometry due to the properties of this negatively-charged residue. Gla is generated by a single enzyme, the gamma-glutamyl carboxylase, which has broad biological impact because VKD proteins have diverse functions that include hemostasis, apoptosis, and growth control. The carboxylase also contains Glas, of unknown function, and is an integral membrane protein with poor sequence coverage. To locate these Glas, we first established methods that resulted in high coverage (92%) of uncarboxylated carboxylase. Subsequent analysis of carboxylated carboxylase identified a Gla-peptide (729-758) and a missing region (625-647) that was detected in uncarboxylated carboxylase. We therefore developed an approach to methylate Gla, which efficiently neutralized Gla and improved mass spectrometric analysis. Methylation eliminated CO2 loss from Gla, increased the ionization of Gla-containing peptide, and appeared to facilitate trypsin digestion. Methylation of a carboxylated carboxylase tryptic digest identified Glas in the 625-647 peptide. These studies provide valuable information for testing the function of carboxylase carboxylation. The methylation approach for studying Gla by mass spectrometry is an important advance that will be broadly applicable to analyzing other VKD proteins.

Hallgren, K. W.; Zhang, D.; Kinter, M.; Willard, B.; Berkner, K. L.

2013-01-01

189

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

190

Determination of the natural radioactivity in Qatarian building materials using high-resolution gamma-ray spectrometry  

NASA Astrophysics Data System (ADS)

This study is aimed at the determination of the activity concentrations of naturally occurring and technically enhanced levels of radiation in building materials used across the State of Qatar. Samples from a range of common building materials, including Qatarian cement, Saudi cement, white cement, sand and washed sand, have been analyzed, in addition to other samples of cement's raw materials and additives collected from the main suppliers in Qatar. In order to establish the activity concentrations associated with the 235,8U and 232Th natural decay chains and 40K, the samples have been studied using a high-resolution, low-background gamma-ray spectrometry set-up. Details of the sample preparation and the gamma-ray spectroscopic analysis techniques are presented, together with the preliminary results of the activity concentrations associated with the naturally occurring radionuclide chains for the building materials collected across the Qatarian peninsula.

Al-Sulaiti, Huda; Alkhomashi, N.; Al-Dahan, N.; Al-Dosari, M.; Bradley, D. A.; Bukhari, S.; Matthews, M.; Regan, P. H.; Santawamaitre, T.

2011-10-01

191

Non invasive measurement of fused solar salts level by gamma-ray spectrometry of potassium natural radioactivity  

NASA Astrophysics Data System (ADS)

A feasibility test, concerning a non invasive method for measuring the level of fused solar salts in a storage vessel, is described. The method is based on the spectrometry of gamma-rays emitted by the salts performed by a scintillation detector positioned outside the vessel insulation. Measurements concerned the fused solar salts (a binary mixture of NaNO3 and KNO3, 60%m and 40%m, respectively) contained in the Casaccia PCS experimental solar facility and working at 408oC. Preliminary results demonstrated the method's feasibility by using the information from the 1.46 MeV 40K gamma-ray line (11% branching ratio). Two deterministic models, as well as Monte Carlo simulations, were implemented for predicting the responses along the tank and specific algorithms, based on 1 or 3 detectors, were developed for the estimation of salt level.

Scafè, R.; Pisacane, F.; Grena, R.; Fabrizi, F.; Mazzei, D.; Crescenzi, T.; Salmi, M.

2008-04-01

192

Overview of reaction mechanisms for calculating the high energy component of fast-nucleon induced gamma spectra  

SciTech Connect

This presentation reviews the current status of quantum mechanical models for understanding the high-energy component of gamma spectra resulting from radiative capture of fast nucleons; i.e., the part of the spectrum that is not amenable to standard statistical model (Hauser-Feshbach) treatments. These models are based on the direct-semidirect (DSD) model and its variants. Included are recent results on the extension of the DSD model to unbound final states, a discussion of problems and improvements in understanding the form factors in this model, and a brief discussion of a model closely related to the DSD, the pure-resonance model.

Dietrich, F.S.

1995-02-21

193

Energy spectra of gamma rays, electrons, and neutrinos produced at interactions of relativistic protons with low energy radiation  

NASA Astrophysics Data System (ADS)

We derived simple analytical parametrizations for energy distributions of photons, electrons, and neutrinos produced in interactions of relativistic protons with an isotropic monochromatic radiation field. The results on photomeson processes are obtained using numerical simulations of proton-photon interactions based on the public available Monte Carlo code SOPHIA. For calculations of energy spectra of electrons and positrons from the pair-production (Bethe-Heitler) process we suggest a simple formalism based on the well-known differential cross section of the process in the rest frame of the proton. The analytical presentations of energy distributions of photons and leptons provide a simple but accurate approach for calculations of broadband energy spectra of gamma rays and neutrinos in cosmic proton accelerators located in radiation dominated environments.

Kelner, S. R.; Aharonian, F. A.

2008-08-01

194

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

195

Use of a Shielded High Resolution Gamma Spectrometry System to Segregate LLW from Contact Handleable ILW Containing Plutonium - 13046  

SciTech Connect

Dounreay Site Restoration Limited (DSRL) have a number of drums of solid waste that may contain Plutonium Contaminated Material. These are currently categorised as Contact Handleable Intermediate Level Waste (CHILW). A significant fraction of these drums potentially contain waste that is in the Low Level Waste (LLW) category. A Canberra Q2 shielded high resolution gamma spectrometry system is being used to quantify the total activity of drums that are potentially in the LLW category in order to segregate those that do contain LLW from CHILW drums and thus to minimise the total volume of waste in the higher category. Am-241 is being used as an indicator of the presence of plutonium in the waste from its strong 59.54 keV gamma-ray; a knowledge of the different waste streams from which the material originates allows a pessimistic waste 'fingerprint' to be used in order to determine an upper limit to the activities of the weak and non-gamma-emitting plutonium and associated radionuclides. This paper describes the main features of the high resolution gamma spectrometry system being used by DSRL to perform the segregation of CHILW and LLW and how it was configured and calibrated using the Canberra In-Situ Object Counting System (ISOCS). It also describes how potential LLW drums are selected for assay and how the system uses the existing waste stream fingerprint information to determine a reliable upper limit for the total activity present in each measured drum. Results from the initial on-site commissioning trials and the first measurements of waste drums using the new monitor are presented. (authors)

Lester, Rosemary; Wilkins, Colin [Canberra UK Ltd, Unit 1 B528.1, Harwell Science Campus, Oxfordshire OX11 0DF (United Kingdom)] [Canberra UK Ltd, Unit 1 B528.1, Harwell Science Campus, Oxfordshire OX11 0DF (United Kingdom); Chard, Patrick [Canberra UK Ltd, Forss Business and Technology park, Thurso, Caithness KW14 7UZ (United Kingdom)] [Canberra UK Ltd, Forss Business and Technology park, Thurso, Caithness KW14 7UZ (United Kingdom); Jaederstroem, Henrik; LeBlanc, Paul; Mowry, Rick [Canberra Industries, Inc., 800 Research Parkway, Meriden, Connecticut, 06450 (United States)] [Canberra Industries, Inc., 800 Research Parkway, Meriden, Connecticut, 06450 (United States); MacDonald, Sanders; Gunn, William [Dounreay Site Restoration Limited, Dounreay, Thurso, Caithness, KW14 7TZ (United Kingdom)] [Dounreay Site Restoration Limited, Dounreay, Thurso, Caithness, KW14 7TZ (United Kingdom)

2013-07-01

196

Etude des desequilibres radioactifs dans les familles de l'uranium par la spectrometrie gamma a basse energie et application a la datation en geologie. (Uranium series radioactive disequilibria study using gamma spectrometry with low energy and application to the dating in geology).  

National Technical Information Service (NTIS)

In this work, the gamma spectrometry with low energy has been used with the help of Ge high purity planar detector, and the means and limits of this spectrometry in the applications to the dating in geology has been studied. A geological sample taken from...

T. Khoukhi

1992-01-01

197

Influence of CdO and gamma irradiation on the infrared absorption spectra of borosilicate glass  

NASA Astrophysics Data System (ADS)

The effect of modifier CdO and gamma irradiation in the dose range of 0.1-60 kGy on the structure of sodium borosilicate glasses is investigated by preparing a series of glasses with compositions xCdO-15Na2O-(70 - x)B2O3-15SiO2; where x = 5, 10, 15, 20, 25 (mol%) by conventional melt quenching technique. FTIR structural studies were carried out on the glass system before and after gamma irradiation. The infrared absorption studies revealed that structure of glass network consists of [BO3], [BO4], [SiO4] and [B-O-Cd] linkages. The modifying action of cadmium oxide on the glass composition is also studied. It is observed that increased gamma radiation dose causes the B-O bond to break and form non-bridging oxygens (NBOs).

Kaur, Ravneet; Singh, Surinder; Pandey, O. P.

2013-10-01

198

Quantitative analysis of gamma-hydroxybutyrate at endogenous concentrations in hair using liquid chromatography tandem mass spectrometry.  

PubMed

A method capable of quantifying endogenous concentrations of gamma-hydroxybutyrate (GHB) in human head hair was developed and validated using liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS). Hair was digested under alkaline conditions, and GHB was isolated using liquid-liquid extraction. LC/MS/MS was performed using atmospheric pressure chemical ionization in the negative mode, multiple reaction monitoring, and deuterated internal standard (GHB-D(6)). Linearity was observed between 0.1 and 100 ng/mg GHB (R(2) = 1.000). The limits of detection and quantitation in human hair were 0.2 and 0.4 ng/mg, respectively. Accuracy at 2 ng/mg and 10 ng/mg was determined to be 97% and 94%, and intra-assay CVs at these concentrations were 5.2% and 7.4% (n = 4). Beta-hydroxybutyrate (BHB), alpha-hydroxybutyrate, gamma-butyrolactone, and 1,4-butanediol did not produce an interference, and there was negligible ion suppression or enhancement from the matrix. PMID:20141559

Stout, Phillip A; Simons, Kelsie D; Kerrigan, Sarah

2010-03-01

199

Self-absorption correction factor applied to 129I measurement by direct gamma-X spectrometry for Fucus serratus samples  

NASA Astrophysics Data System (ADS)

Self-absorption corrections have been determined for the energies characterising 129I below 40 keV in the frame of studying Fucus serratus samples by direct gamma-X spectrometry. This work was performed on a large spatio-temporal scale in order to integrate the fluctuations of the matrix. More than 200 samples monthly collected from January 1983 to December 1996 along the French Atlantic and English Channel coasts, have been measured as part of the Permanent Observatory of the radioactivity programme of the Institut de Radioprotection et de Sûreté Nucléaire (IRSN). A relationship has been established between experimental mass attenuation coefficients at low energy and the 40K concentrations of the samples, where the latter showed the same temporal variation as the 127I concentration (iodine stable isotope). Based on the mean correction factors determined in the present work, a simplified method is proposed to quantify the content of 129I. The direct gamma-X spectrometry results obtained in this way are in good agreement with those reported by Patti et al. (Radioprotection 23 (1988) 381) using neutron activation analysis for the samples collected between October 1983 and December 1984 at Herquemoulin, located near the La Hague reprocessing plant.

Lefèvre, O.; Bouisset, P.; Germain, P.; Barker, E.; Kerlau, G.; Cagnat, X.

2003-06-01

200

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

201

LEAST-SQUARE ANALYSIS OF GAMMA-RAY PULSE HEIGHT SPECTRA  

Microsoft Academic Search

In this analysis the pulse height spectrum due to a polyenergetic ; distribution of gamma rays is synthesized by using a series of normalized pulse ; height distributions resulting from the monoenergetic components in the incident ; beam. All of these monoenergetic pulse height distributions are weighted so ; their sum is a best fit, based upon a least-square criterion,

Trombka

1962-01-01

202

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

Microsoft Academic Search

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

Martin Eugene Keillor

2000-01-01

203

Resonance-Averaged (N, gamma ) Spectra and Their Applications to Nuclear Structure.  

National Technical Information Service (NTIS)

Because they populate final states without regard to the details of the nucleonic configurations, neutron-capture gamma rays are ideally suited for locating essentially all the low lying nuclear states whose spins lie within a few units of that of the cap...

C. W. Reich

1978-01-01

204

Bayesian methods for inferring soil contamination profiles from neutron-induced gamma-ray spectra  

NASA Astrophysics Data System (ADS)

Prompt-gamma neutron-activation analysis offers a potential for noninvasive characterization of contaminated soil. In this method, neutron irradiation of the surface induces a capture-gamma-ray signature from the contaminant which can be identified in a gamma-ray energy spectrum measured at the surface. The fundamental problem is to infer the contaminant concentration profile from the measured capture-gamma-ray intensities which include gamma-ray contributions from all soil depths. Radiation-transport theory is used to simulate the neutron field and both the uncollided and first-scattered gamma-ray components in uniform soil compositions. Simulated data, generated for any assumed one-dimensional contamination profile, are used to test several methods of profile reconstruction. The methods applied to solve this inverse problem include: linear (Tikhonov) regularization with and without positivity constraints, Backus-Gilbert smoothing, maximum-entropy Bayesian optimization, and a new Bayesian approach that accepts prior information in the form of a multivariate lognormal probability density. A tutorial on inverse theory is provided to relate the seemingly disparate approaches of Bayesian optimization and regularization of a Fredholm integral equation. Particular attention is given to using Shannon-Jaynes configurational entropy as a prior constraint. In the Bayesian context, all methods seek the maximum-a-posteriori (MAP) solution lying at the mode of Bayes' posterior. Comparative inverse MAP solutions are presented for bilinear and step concentration profiles. Maximum-entropy and lognormal-prior methods, which enforce positivity and accept additional prior information, successfully locate bulk concentrations with reasonable peak estimates and minimum computation. Practical depth resolutions are limited to a range of 60 cm in nominal soil by poor neutron penetration. The variance of Bayes' posterior probability distribution is investigated to assess the utility of the MAP concentration profile inferred from a single gamma-ray spectrum. Relative-a-posteriori (RAP) probability contours are sampled to illustrate the range of alternative solutions. Then, maximum-entropy profiles from several RAP contours are used to predict the range of individual MAP solutions that would be computed for replicate data sets. This new method of exploratory variance analysis is referred to as maximum-entropy-relative-a-posteriori (MERAP) analysis. Example problems emphasize proof-of-principle demonstrations rather than development of optimized, robust algorithms.

Letellier, Bruce Clark

1998-11-01

205

Gamma Ray and Hadron generated Cerenkov Photon Spectra at Various Observational Altitudes  

NASA Astrophysics Data System (ADS)

Incident ?Cerenkov photon spectra at various observation altitudes are derived after applying wavelength dependent corrections due to attenuation in the atmosphere during their propagation. These spectra are found to be both altitude and primary energy dependent, the peak of which shifts towards shorter wavelength with increasing altitude of observation for a given primary. Also it shifts towards shorter wavelength with increasing primary energy at a given altitude. The fraction of UV component in this spectrum is estimated both for ?- ray and hadron primaries at various observation altitudes and energies. Hadron generated ?Cerenkov spectra are richer in UV light at higher altitudes. Thus the fraction of UV to visible light in the ?Cerenkov spectrum could be a useful parameter to separate ?- rays from cosmic rays specially at lower primary energies.

Majumdar, P.; Acharya, B. S.; Bhat, P. N.; Chitnis, V. R.; Rahman, M. A.; Singh, B. B.; Vishwanath, P. R.

2001-08-01

206

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

Microsoft Academic Search

BackgroundMatrix-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.MethodsMALDI-TOF MS was performed on 30 reference and 167 clinical isolates followed by prospective examination

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

2011-01-01

207

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

208

The effect of different sample-calibrant composition in gamma-ray spectrometry for the assessment of the radiation dose rate in the luminescence dating of sediments  

Microsoft Academic Search

One of the basic steps in luminescence dating is the determination of the annual radiation dose. Among the suitable determination\\u000a methods in the case of sediment dating is HPGe gamma-ray spectrometry, primarily yielding the concentrations of K, Th and\\u000a U via measurement of gamma-rays emitted by 40K and by 232Th and 235,238U and their decay products. These determinations involve both

F. De Corte; D. Vandenberghe; S. M. Hossain; A. De Wispelaere; P. Van den Haute

2004-01-01

209

A nondestructive method based on gamma spectrometry for the measurements of plutonium hold-up or plutonium wastes  

SciTech Connect

With respect to in-plant holdup and wastes, plutonium quantities are measured in most cases by nondestructive methods such as neutron counting, gamma-photon counting, and infrared detection. These methods are often imperfect for various reasons: difficult access to sample, highly radioactive background, screens, etc. It is therefore of interest to develop other methods in order to check the results from these techniques or improve them. The quick method described is used for measuring the quantities of plutonium kept in various types of containers such as gloveboxes, cans, etc. It is applicable to the evaluation of sample masses ranging from a few tens of milligrams to several tens of grams. It is based on the gamma-ray spectrometry technique with germanium detectors. Gamma rays emitted by plutonium isotopes in the 100- to 500-keV energy range permit us, after a quick isotope composition determination, to obtain the plutonium total mass corrected for absorption and self-absorption by extrapolation to infinite energy of the apparent masses calculated for the energies of the selected peaks. This method has been used for several months in different fields such as the accountancy of the plutonium holdup in fuel fabrication plants; the reprocessing and the storage of radioactive wastes; and the supervision of the dismantlement.

Morel, J.; Chauvenet, B.; Etcheverry, M.; Louppe, L.; Monier, J.

1987-01-01

210

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

211

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

212

Determination of fluorine by the spectrometry of prompt gamma-rays  

Microsoft Academic Search

The use, for analysis, of prompt gamma-rays excited by 5 MeV alpha-particles from the reactions19F(?,???)19F,19F(?, n?)22Na and19F(?, p?)22NE, was studied. The precision of the analyses depended on the gamma-ray energy used for the measurement. Relative standard\\u000a deviations were ±1.8, ±0.9 and ±1.3% using the 110-, 197- or 1275 keV gamma-rays. The method was tested with N. I. M. standard\\u000a materials

I. S. Giles; M. Peisach

1976-01-01

213

Comparison between the Spectra of Gamma Radiation for Climate Dry Periods and Rainy in the Southeast of Brazil  

NASA Astrophysics Data System (ADS)

Through this work, present themselves the results obtained for the spectra of ionizing radiation (X-rays and gamma) environmental southeast Brazil for the periods of dry and rainy climate, respectively. One of the objectives this work is promoting through analysis of the results a better understand, in the educational area, the physical processes related to the background radiation of the places where measurements were made. In Brazil, there is still little information about the radiation from soil, radon gas atmospheric, cosmic and artificial origin. Measurements of gamma radiation spectra were performed with a scintillator of NaI (Tl) (volume 300 cm3) mounted within an aluminum cell and coupled to a photomultiplier tube, which in turn is coupled through an interface to specify a notebook for storage of data. The measurement of X and gamma rays photons occur of way omnidirectional without distinction as to direction. The data acquisition was performed at fixed intervals of 1 minute continuously for the entire period of dry climate (June to October) and rainy (December 2012 to January 2013). Figures 1 and 2 show the results obtained for both periods, dry and rainy, respectively. Regarding the graph of Figure 1, is evidenced a cycle of 24 hours in the radiation spectrum. In this period without rain the radiation increases always between sunrise sunset until 11 - 12 hours local, due to the increased presence of radon gas (222Rn) which decays after 3.8 days in 214Pb and 214Bi, emitting photons in the range of energy the detector is measuring (0.030 to 3.0 MeV). The graph in Figure 2 shows that during the rainy period, there was a significant increase in radiation intensity, in addition to that already shown in the dry times that for certain time intervals. This increase is due to when occurs precipitation, the amount of radon gas increases because of the phenomenon of washing the lower atmosphere where the gas is suspended and diluted in water droplets. In the rainy period, the periodicity that is present in the spectrum of the dry climate is practically destroyed due to the interference of photons gamma of radon gas from the rain.

Gomes, M. P.; Martin, I. M.

2013-05-01

214

Direct determination of 226 Ra in NORM\\/TENORM matrices by gamma-spectrometry  

Microsoft Academic Search

Summary  The main shortcoming with the procedure to determine 226Ra in a gamma spectrum of an environmental sample by means of the 214Bi and 214Pb photopeaks is the likelihood of 222Rn leakage from the sample counting vial. An option to make such determination is to disregard the 226Ra gamma-contributions to the spectrum, other than 186.2 keV (3.5%), subtracting the 235U contribution

J. Justo; H. Evangelista; A. S. Paschoa

2006-01-01

215

The effect of energy resolution on the extraction of information content from gamma-ray spectra  

NASA Astrophysics Data System (ADS)

Rapid unambiguous identification of illicit radioactive materials is a matter of international concern that has yet to be fully attained. This is particularly true for shielded fissile materials in the presence of background radiation and routinely encountered benign radionuclides. We present a systematic treatment of the effect of detector resolution on the identification of nuclides in simple and complex shielded ?-ray spectra. Case studies of some problematic spectra with 1000 counts suggest that, at moderate count rates, near-unambiguous identification (<1% probability of misidentification) of potential fissile sources requires a detector with an energy resolution of at least 1-2% at 662 keV. While somewhat limited in scope, the study establishes a quantitative basis for the comparative evaluation of detectors of comparable efficiency.

Nelson, Karl E.; Gosnell, Thomas B.; Knapp, David A.

2011-12-01

216

Analyses of the gamma-ray pulse-height spectra from the lunar surface  

NASA Technical Reports Server (NTRS)

The method of inferring photon spectra from an analysis of the measured pulse-height spectrum is considered along with the spectrum shape and its variation energy. The case is examined where photoelastic absorption predominates, and Compton scattering and pair production are negligible. The analytic method for obtaining the elemental composition from the observed lunar surface spectrum is described, and theoretical and calculated weight fraction fluxes for average lunar composition are tabulated.

Trombka, J. I.

1973-01-01

217

Identification of 94Kr and 143Xe, and Measurement of gamma-Ray Spectra and Half-Lives of Nuclides in the Mass Chains 93, 94, and 143  

Microsoft Academic Search

Fission-produced nuclides 94Kr and 143Xe have been measured directly using on-line mass separation. The half-lives derived from the beta-decay curve are 0.20 +\\/- 0.01 and 0.3 +\\/- 0.03 sec, respectively. gamma-ray spectra in the mass chain 93 have been measured and various gamma peaks were assigned to the individual nuclides.

S. Amiel; H. Feldstein; M. Oron; E. Yellin

1972-01-01

218

Detailed investigation of the buildup factors and spectra for point isotropic gamma-ray sources in the vicinity of the K edge in lead  

Microsoft Academic Search

Detailed calculations of the buildup factors and spectra of gamma rays including fluorescence radiations in lead are carried out using a discrete ordinates code, PALLAS-PL,SP-Br. The exposure and absorbed dose buildup factors with and without fluorescence are tabulated for 11 source energies from 0.09 to 0.3 MeV for penetration depths up to 40 mfp. Important characteristics of the gamma-ray transport

S. Tanaka; K. Takeuchi

1986-01-01

219

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

220

A GROUP SEPARATION METHOD FOR GAMMA SPECTROMETRY OF COMPLEX RADIONUCLIDE MIXTURES, WITH SPECIAL APPLICATION TO STAINLESS STEEL AND ITS CORROSION PRODUCTS  

Microsoft Academic Search

Short anion exchange columns coupled in series and saturated with ; chlordie, citrate, and hydroxide ions have been used for simple and vary radid ; separations of common elements in water solutions as a pretreatment for ; subanquese analysis with gamma spectrometry. A method was developed for the ; analysis of stainless steel, its corrosion products, and otaer elements present

K. Samsahl; J. Åselius; Karl F. Nakken; K. Hartiala; S. Veige; E. Diczfalusy

1958-01-01

221

Effects of gamma radiation on commercial food packaging films—study of changes in UV/VIS spectra  

NASA Astrophysics Data System (ADS)

The effects of gamma irradiation doses up to 100 kGy on the optical properties of different commercial packaging films were studied in this paper. The packaging films analyzed were: polyethylene "LDPE", amide 6-amide 6.6 copolymer "PA6-PA6.6" and poly(ethylene terephthalate) "PET". An investigation on film samples before and after irradiation was performed by UV/VIS spectroscopy. The results showed that, in the absorption spectra of irradiated LDPE and PA6-PA6.6 films, a red-shift in the wavelength of the UV cutoff and a marked reduction in % transmittance (at low wavelengths) occur with increasing radiation dose. With respect to PET samples, no significant changes were observed in either light absorption or transmittance.

Moura, E. A. B.; Ortiz, A. V.; Wiebeck, H.; Paula, A. B. A.; Silva, A. L. A.; Silva, L. G. A.

2004-09-01

222

Energy spectra of gamma rays, electrons, and neutrinos produced at proton-proton interactions in the very high energy regime  

NASA Astrophysics Data System (ADS)

We present new parameterizations of energy spectra of secondary particles, ? mesons, gamma rays, electrons, and neutrinos produced in inelastic proton-proton collisions. The simple analytical approximations based on simulations of proton-proton interactions using the public available SIBYLL code provide very good accuracy for energy distributions of secondary products in the energy range above 100 GeV. Generally, the recommended analytical formulas deviate from the simulated distributions within a few percent over a large range of x=Ei/Ep—the fraction of energy of the incident proton transferred to the secondaries. Finally, we describe an approximate procedure of continuation of calculations towards low energies, down to the threshold of ?-meson production.

Kelner, S. R.; Aharonian, F. A.; Bugayov, V. V.

2006-08-01

223

Extensions of the direct-semidirect model for calculating the high energy component of fast-nucleon induced gamma spectra  

SciTech Connect

This section reviews extensions and variations of the direct-semidirect (DSD) model for understanding the high-energy component of gamma spectra resulting from radiative capture of fast nucleons; i.e., the part of the spectrum that is not amenable to standard statistical model (Hauser-Feshbach) treatments. We describe recent results on the extension of the DSD model to unbound final states, including comparison with proton and neutron capture data. The importance of including convective-current magnetic radiation to explain proton capture angular distributions in the 30 MeV region is shown. We conclude with a brief discussion of a model closely related to the DSD, the pure-resonance model.

Dietrich, F S

2000-05-22

224

Electrospray ionization mass spectra of piperazimycins A and B and gamma-butyrolactones from a marine-derived Streptomyces sp.  

PubMed

Chemical investigation of the marine-derived Streptomyces sp. Act8015 led to the isolation of two cyclic peptide antibiotics, piperazimycins A and B (1a, 1b). Their structures were confirmed on the basis of a detailed HRESI-MS/MS analysis. Additionally, a new butanolide, 4,10-dihydroxy-10-methyl-dodecan-4-olide (2), and the respective acid, 4,10-dihydroxy-10-methyl-dodecanoic acid (3a) were identified. Further isolated compounds were staurosporin, adenine, indole-3-carboxylic acid, ferulic acid, tryptophol, and three gamma-butyrolactones: virginiae butanolide E (4e) and Graefe's Factors I (4f) and III (4g). The structures of 2 and 3a were confirmed by detailed 1D and 2D NMR studies and MS spectra and by comparison with related structures. A full signal assignment of virginiae butanolide E (4e) is reported here for the first time. PMID:19194032

Shaaban, Khaled A; Shaaban, Mohamed; Facey, Petrea; Fotso, Serge; Frauendorf, Holm; Helmke, Elisabeth; Maier, Armin; Fiebig, Heinz H; Laatsch, Hartmut

2008-12-01

225

Attributes from NMIS Time Coincidence, Fast-Neutron Imaging, Fission Mapping, And Gamma-Ray Spectrometry Data  

SciTech Connect

This work tests a systematic procedure for analyzing data acquired by the Nuclear Materials Identification System (NMIS) at Oak Ridge National Laboratory with fast-neutron imaging and high-purity germanium (HPGe) gamma spectrometry capabilities. NMIS has been under development by the US Department of Energy Office of Nuclear Verification since the mid-1990s, and prior to that by the National Nuclear Security Administration Y-12 National Security Complex, with NMIS having been used at Y-12 for template matching to confirm inventory and receipts. In this present work, a complete set of NMIS time coincidence, fast-neutron imaging, fission mapping, and HPGe gamma-ray spectrometry data was obtained from Monte Carlo simulations for a configuration of fissile and nonfissile materials. The data were then presented for analysis to someone who had no prior knowledge of the unknown object to accurately determine the description of the object by applying the previously-mentioned procedure to the simulated data. The best approximation indicated that the unknown object was composed of concentric cylinders: a void inside highly enriched uranium (HEU) (84.7 {+-} 1.9 wt % {sup 235}U), surrounded by depleted uranium, surrounded by polyethylene. The final estimation of the unknown object had the correct materials and geometry, with error in the radius estimates of material regions varying from 1.58% at best and 4.25% at worst; error in the height estimates varied from 2% to 12%. The error in the HEU enrichment estimate was 5.9 wt % (within 2.5{sigma} of the true value). The accuracies of the determinations could be adequate for arms control applications. Future work will apply this iterative reconstructive procedure to other unknown objects to further test and refine it.

Swift, Alicia L [ORNL; Grogan, Brandon R [ORNL; Mullens, James Allen [ORNL; Hayward, J P [University of Tennessee, Knoxville (UTK); Mihalczo, John T [ORNL

2012-01-01

226

Dose rate constant of a Cesium-131 interstitial brachytherapy seed measured by thermoluminescent dosimetry and gamma-ray spectrometry  

SciTech Connect

The aim of this work was to conduct an independent determination of the dose rate constant of the newly introduced Model CS-1 {sup 131}Cs seed. A total of eight {sup 131}Cs seeds were obtained from the seed manufacturer. The air-kerma strength of each seed was measured by the manufacturer whose calibration is traceable to the air-kerma strength standard established for the {sup 131}Cs seeds at the National Institute of Standards and Technology (1{sigma} uncertainty <1%). The dose rate constant of each seed was measured by two independent methods: One based on the actual photon energy spectrum emitted by the seed using gamma-ray spectrometry and the other based on the dose-rate measured by thermoluminescent dosimeter (TLD) in a Solid Water{sup TM} phantom. The dose rate constant in water determined by the gamma-ray spectrometry technique and by the TLD dosimetry are 1.066{+-}0.064 cGyh{sup -1}U{sup -1} and 1.058{+-}0.106 cGyh{sup -1}U{sup -1}, respectively, showing excellent agreement with each other. These values, however, are approximately 15% greater than a previously reported value of 0.915 cGyh{sup -1}U{sup -1} [Med. Phys. 31, 1529-1538 (2004)]. Although low-energy fluorescent x rays at 16.6 and 18.7 keV, originating from niobium present in the seed construction, were measured in the energy spectrum of the {sup 131}Cs seeds, their yields were not sufficient to lower the dose rate constant to the value of 0.915 cGyh{sup -1}U{sup -1}. Additional determinations of the dose rate constant may be needed to establish an AAPM recommended consensus value for routine clinical use of the {sup 131}Cs seed.

Chen, Z.; Bongiorni, P.; Nath, R. [Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut 06504 (United States)

2005-11-15

227

Modern aerial gamma-ray spectrometry and regional potassium map of the conterminous United States  

USGS Publications Warehouse

Aerial gamma-ray surveys of the natural environment measure the flux of gamma rays produced by the radioactive decay of 40K, 214Bi, and 208Tl in the upper 10-20 cm of surface materials. 40K is a radioactive potassium isotope which can be used to estimate the total amount of potassium in the soils and rocks. 214Bi is a decay product of the 238U radioactive decay series and is used to estimate the uranium concentrations, and 208Tl, a decay product of the 232Th radioactive decay series, is used to estimate thorium concentrations. Aerial gamma-ray data covering the 48 contiguous states of the United States have been compiled to produce maps showing the distributions of equivalent uranium, equivalent thorium, and potassium. This compilation involved processing the aerial survey data from about 470 1?? ?? 2?? quadrangle maps. ?? 1990.

Duval, J. S.

1990-01-01

228

Analysis of gamma-ray spectra from foils activated in a range-thick lead target by 800-MeV protons. Final technical report  

SciTech Connect

Approximately 400 gamma-ray spectra have been analyzed to obtain the types and quantities of radioisotopes produced when 800-MeV protons interact with a range-thick lead target. These spectra were obtained from the radioactive decay of product isotopes in lead disks placed at various depths and radial positions within the target. These spectra were analyzed with the computer code HYPERMET and the photopeak areas were reduced to nuclei produced per incident proton per cubic centimeter of material. Product nuclei ranged from atomic mass 160 to mass 206 and over a range of half lives from a few minutes to several weeks. The results of this analysis have been outlined in this report and transmitted on computer disk to Los Alamos National Laboratory. The consistency of these analyses have been confirmed by a comparison of photopeak areas obtained at LANL with the computer code GAMANAL with those from HYPERMET for two gamma-ray spectra. Also, the nuclear production per proton per cm{sub 3} obtained from these two spectra analyzed both at LANL and at EKU have been found to agree to within the statistical accuracy of the peak-fitting programs. This analysis of these 400 gamma-ray spectra has determined the nuclear production per incident proton per cm{sub 3} at five regularly-spaced radial positions and depths up to 40 cm into a range-thick lead target.

Laird, C.E.; Mullins, D.H.

1995-06-12

229

Gamma spectrometry and chemical characterization of ceramic seeds with samarium-153 and holmium-166 for brachytherapy proposal.  

PubMed

Ceramic seeds were synthesized by the sol-gel technique with Si:Sm:Ca and Si:Ho:Ca. One set of seeds was irradiated in the TRIGA type nuclear reactor IPR-R1 and submitted to instrumental neutron activation analysis (INAA), K(0) method, to determine mass percentage concentration of natural samarium and holmium in the seed as well as to determine all existing radionuclides and their activities. Attention was paid to discrimination of Si-31, Ca-40, Ca-45, Ca-47, Ca-49, Sm-145, Sm-155, Sm-153 and Ho-166. A second sample was submitted to atomic emission spectrometry (ICP-AES) also to determine samarium and holmium concentrations in weight. A third sample was submitted to X-ray fluorescence spectrometry to qualitatively determine chemical composition. The measured activity was due to Sm-153 and Ho-166 with a well-characterized gamma spectrum. The X-ray fluorescence spectrum demonstrated that there is no discrepancy in seed composition. The maximum ranges in the water of beta particles from Sm-153 and Ho-166 decay were evaluated, as well as the dose rate and total dose delivered within the volume delimited by the range of the beta particles. The results are relevant for investigation of the viability of producing Sm-153 and Ho-166 radioactive seeds for use in brachytherapy. PMID:20685128

Valente, Eduardo S; Campos, Tarcísio P R

2010-12-01

230

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

231

Gamma-irradiated dry fruits. An example of a wide variety of long-time dependent EPR spectra.  

PubMed

EPR spectra of dry, sugar containing fruits--raisins, sultanas, figs, dates, peaches, blue plums and chokeberry recorded before and after irradiation with gamma-rays, are reported. It is shown that weak singlet EPR line with 2.0031+/-0.0005 can be recorded before irradiation of seeds, stones or skin of chokeberry, figs and raisins as well as flesh of blue plum, raisins and peaches. EPR signals of various shape are distinguished after irradiation in different parts of the fruits, as well as in randomly cut pieces of them: As a result, randomly cut pieces of dry fruits suitable for EPR studies, containing various constituents, exhibit different in shape and intensity EPR spectra. Kinetic studies followed for 1 year on the time stability of all reported EPR signals indicate that intensity ratio between the simultaneously appearing EPR signals in particular fruit varies from 1:20 immediately after irradiation to 1:0.5 at the end of the period. These observations open a new possibility for identification of irradiated fruits - using the magnitude of the intensity ratio to find the approximate date of radiation processing in the first ca. 30-100 days. PMID:16497546

Yordanov, Nicola D; Pachova, Zdravka

2006-03-13

232

A review of nationwide radioactivity comparisons on gamma-ray spectrometry organized by the NIRP, China.  

PubMed

Six comparison exercises on radioactivity measurement by ?-spectrometry have been organized by NIRP in China since 2007. The type of measured nuclides changed from natural to man-made over this period. A total of 188 samples were prepared and distributed to 39 different participating laboratories and 528 radionuclide assays have been performed. A perceptible laboratory performance improvement was observed with the average percentage of acceptable scores being 87% in 2008, increasing to 92% in 2012. PMID:24369889

Tuo, Fei; Xu, Cuihua; Zhang, Qing; Zhang, Jing; Zhou, Qiang; Li, Wenhong; Zhang, Jianfeng; Su, Xu

2014-05-01

233

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

234

Quantitative waste assay using gamma-ray spectrometry and computed tomography.  

National Technical Information Service (NTIS)

Simulated and real experimental data are used to investigate the use of (1) active computed tomography (ACT) to obtain images of attenuated gamma rays from a waste-canister interior; (2) passive computed tomography (PCT) to locate and determine the radioi...

H. E. Martz G. P. Roberson C. Robert-Coutant D. J. Schneberk D. C. Camp

1992-01-01

235

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

236

The influence of exogenous conditions on mobile measured gamma-ray spectrometry  

NASA Astrophysics Data System (ADS)

In the past, gamma ray measurements have been used for geological surveys and exploration using airborne and borehole logging systems. For these applications, the relationships between the measured physical parameter - the concentration of natural gamma emitters 40K, 238U and 232Th - and geological origin or sedimentary developments are well described. Based on these applications and knowledge in combination with adjusted sensor systems, gamma ray measurements are used to derive soil parameters to create detailed soil maps e.g., in digital soil mapping (DSM) and monitoring of soils. Therefore, not only qualitative but also quantitative comparability is necessary. Grain size distribution, type of clay minerals and organic matter content are soil parameters which directly influence the gamma ray emitter concentration. Additionally, the measured concentration is influenced by endogenous processes like soil moisture variation due to raining events, foggy weather conditions, or erosion and deposition of material. A time series of gamma ray measurements was used to observe changes in gamma ray concentration on a floodplain area in Central Germany. The study area is characterised by high variations in grain size distribution and occurrence of flooding events. For the survey, we used a 4l NaI(Tl) detector with GPS connection mounted on a sledge, which is towed across the field sites by a four-wheel-vehicle. The comparison of data from different time steps shows similar structures with minor variation between the data ranges and shape of structures. However, the data measured during different soil moisture contents differ in absolute value. An average increase of soil moisture of 36% leads to a decrease of Th (by 20%), K (by 29%), and U (by 41%). These differences can be explained by higher attenuation of radiation during higher soil moisture content. The different changes in nuclide concentration will also lead to varying ratios. We will present our experiences concerning the measurement under variable field conditions and their impacts on gamma ray data quality. These activities are done within the iSOIL project. iSOIL- Interactions between soil related sciences - Linking geophysics, soil science and digital soil mapping is a Collaborative Project (Grant Agreement number 211386) co-funded by the Research DG of the European Commission within the RTD activities of the FP7 Thematic Priority Environment; iSOIL is one member of the SOIL TECHNOLOGY CLUSTER of Research Projects funded by the EC.

Dierke, C.; Werban, U.; Dietrich, P.

2012-12-01

237

Measurement of gamma radiation levels in soil samples from Thanjavur using ?-ray spectrometry and estimation of population exposure  

PubMed Central

This study assesses the level of terrestrial gamma radiation and associated dose rates from the naturally occurring radionuclides 232Th, 238U and 40K in 10 soil samples collected from Thanjavur (Tamil Nadu, India) using ?-ray spectrometry. The activity profile of radionuclides has clearly showed the existence of low level activity in Thanjavur. The geometric mean activity concentrations of 232Th, 238U and 40K is 42.9±9.4 Bq.kg?1, 14.7±1.7 Bq.kg?1 and 149.5±3.1 Bq.kg?1 respectively are derived from all the soil samples studied. The activity concentration of 232Th, 238U and 40K in soil is due to the presence of metamorphic rocks like shale, hornblende-biotite gneiss and quartzofeldspathic gneiss in these areas. Gamma absorbed dose rates in air outdoors were calculated to be in the range between 32 nGy.h?1 and 59.1 nGy.h?1 with an arithmetic mean of 43.3 ±9 nGy.h?1. This value is lesser than the population weighted world-averaged of 60 nGy.h?1. Inhabitants of Thanjavur are subjected to external gamma radiation exposure (effective dose) ranging between 39.2 and 72.6 ?Sv.y?1 with an arithmetic mean of 53.1±11 ?Sv.y?1. The values of the external hazard index determined from the soil radioactivity of the study area are less than the recommended safe levels.

Senthilkumar, B.; Dhavamani, V.; Ramkumar, S.; Philominathan, P.

2010-01-01

238

Structural characterization of methylenedianiline regioisomers by ion mobility-mass spectrometry, tandem mass spectrometry, and computational strategies: I. Electrospray spectra of 2-ring isomers.  

PubMed

Purified methylenedianiline (MDA) regioisomers were structurally characterized and differentiated using tandem mass spectrometry (MS/MS), ion mobility-mass spectrometry (IM-MS), and IM-MS/MS in conjunction with computational methods. It was determined that protonation sites on the isomers can vary depending on the position of amino groups, and the resulting protonation sites play a role in the gas-phase stability of the isomer. We also observed differences in the relative distributions of protonated conformations depending on experimental conditions and instrumentation, which is consistent with previous studies on aniline in the gas phase. This work demonstrates the utility of a multifaceted approach for the study of isobaric species and elucidates why previous MDA studies may have been unable to detect and/or differentiate certain isomers. Such analysis may prove useful in the characterization of larger MDA multimeric species, industrial MDA mixtures, and methylene diphenyl diisocyanate (MDI) mixtures used in polyurethane synthesis. PMID:24678803

Forsythe, Jay G; Stow, Sarah M; Nefzger, Hartmut; Kwiecien, Nicholas W; May, Jody C; McLean, John A; Hercules, David M

2014-05-01

239

Search for lost or orphan radioactive sources based on NaI gamma spectrometry  

Microsoft Academic Search

Within recent decades many radioactive sources have been lost, stolen, or abandoned, and some have caused contamination or irradiation of people. Therefore reliable methods for source recovery are needed. The use of car borne NaI(Tl) detectors is discussed. Standard processing of spectra in general can disclose strong and medium level signals from manmade nuclides. But methods for detecting low level

H. K. Aage; U. Korsbech

2003-01-01

240

Recognizing alpha-, beta- or gamma-substitution in pyridines by mass spectrometry.  

PubMed

A general mass spectrometric method able to recognize the site of substitution of monosubstituted pyridines is described. The method requires that the molecule under investigation forms, upon ionization and dissociation, the respective alpha-, beta- or gamma- pyridinium ion of m/z 78. Pyridinium ions are stable and common fragments of ionized and protonated pyridines and are found to function as appropriate structurally diagnostic fragment ions. They can be identified by their characteristic and nearly identical collision-induced dissociation behavior and distinguished by the combined use of two structurally diagnostic ion/molecule reactions with acetonitrile and 2-methyl-1,3-dioxolane. alpha-, beta- or gamma-substitution in pyridines can, therefore, be securely recognized via an MS-only method based on structurally diagnostic ions and by the inspection of a single molecule (no need for intracomparisons within the whole set of isomers). PMID:18563867

Corilo, Yuri E; Eberlin, Marcos N

2008-12-01

241

Gamma ray spectrometry logs as a hydrocarbon indicator for clastic reservoir rocks in Egypt.  

PubMed

Petroleum oil is an important source for the energy in the world. The Gulf of Suez, Nile Delta and South Valley are important regions for studying hydrocarbon potential in Egypt. A thorium normalization technique was applied on the sandstone reservoirs in the three regions to determine the hydrocarbon potentialities zones using the three spectrometric radioactive gamma ray-logs (eU, eTh and K% logs). The conventional well logs (gamma-ray, deep resistivity, shallow resistivity, neutron, density and sonic logs) are analyzed to determine the net pay zones in these wells. Indices derived from thorium normalized spectral logs indicate the hydrocarbon zones in petroleum reservoirs. The results of this technique in the three regions (Gulf of Suez, Nile Delta and South Valley) are in agreement with the results of the conventional well log analyses by ratios of 82%, 78% and 71% respectively. PMID:23306160

Al-Alfy, I M; Nabih, M A; Eysa, E A

2013-03-01

242

Monte Carlo Solutions for Selected Problems in Gamma-Ray Spectrometry and Nuclear Activation Analysis  

NASA Astrophysics Data System (ADS)

A comprehensive calibration of gamma-ray spectrometers cannot be obtained purely on experimental basis. Problems like self-attenuation effects, coincidence-summing effects and non-uniform source distribution (resulting e.g. from neutron self-shielding in NAA) can be efficiently solved by Monte Carlo simulation. The application of the GESPECOR code to these problems is presented and the associated uncertainty is discussed.

Sima, Octavian

2008-08-01

243

Self-absorption correction for gamma spectrometry of powdered milk samples using Marinelli beaker  

Microsoft Academic Search

Self-absorption was measured for the activity calculation of the 1460.8 and 2614.47keV lines of the 40K and the 208Tl, respectively, in powdered milk samples. Five Marinelli beakers were prepared with powdered milk in different degrees of compaction and the spectra were measured with an HPGe detector. The detection efficiency versus density was obtained and the self-absorption correction factors versus density

F. L Melquiades; C. R Appoloni

2001-01-01

244

Gamma-irradiated dry fruits. An example of a wide variety of long-time dependent EPR spectra  

NASA Astrophysics Data System (ADS)

EPR spectra of dry, sugar containing fruits—raisins, sultanas, figs, dates, peaches, blue plums and chokeberry recorded before and after irradiation with gamma-rays, are reported. It is shown that weak singlet EPR line with 2.0031 ± 0.0005 can be recorded before irradiation of seeds, stones or skin of chokeberry, figs and raisins as well as flesh of blue plum, raisins and peaches. EPR signals of various shape are distinguished after irradiation in different parts of the fruits, as well as in randomly cut pieces of them: Seeds of raisins, chokeberry and figs give a singlet line. Stones from blue plums and peaches exhibit typical "cellulose-like" EPR signal consisting of an intense singlet line with g = 2.0033 ± 0.0005 and 2 week satellite lines situated ca. 30 G left and right to it. Stones of dates are the only sample in which "sugar-like" spectrum is recorded. Skin of raisins and figs exhibits "sugar-like" EPR spectrum whereas that of dates and chokeberry—a singlet line. Under the same experimental conditions skin of sultanas, peaches and blue plums are EPR silent. Flesh of raisins, sultanas, figs, dates and peaches exhibits "sugar-like" EPR spectrum, flesh of blue plums gives a singlet EPR line and that of chokeberry is EPR silent. As a result, randomly cut pieces of dry fruits suitable for EPR studies, containing various constituents, exhibit different in shape and intensity EPR spectra. Kinetic studies followed for 1 year on the time stability of all reported EPR signals indicate that intensity ratio between the simultaneously appearing EPR signals in particular fruit varies from 1:20 immediately after irradiation to 1:0.5 at the end of the period. These observations open a new possibility for identification of irradiated fruits - using the magnitude of the intensity ratio to find the approximate date of radiation processing in the first ca. 30-100 days.

Yordanov, Nicola D.; Pachova, Zdravka

2006-03-01

245

Pu abundances, concentrations, and isotopics by x- and gamma-ray spectrometry assay techniques  

SciTech Connect

Two x- and gamma-ray systems were recently installed at-line in gloveboxes and will measure Pu solution concentrations from 5 to 105 g/L. These NDA technique, developed and refined over the past decade, are now used domestically and internationally for nuclear material process monitoring and accountability needs. In off- and at-line installations, they can measure solution concentrations to 0.2%. The K-XRFA systems use a transmission source to correct for solution density. The gamma-ray systems use peaks from 59- to 208-keV to determine solution concentrations and relative isotopics. A Pu check source monitors system stability. These two NDA techniques can be combined to form a new, NDA measurement methodology. With the instrument located outside of a glovebox, both relative Pu isotopics and absolute Pu abundances of a sample located inside a glovebox can be measured. The new technique works with either single or dual source excitation; the former for a detector 6 to 20 cm away with no geometric corrections needed; the latter requires geometric corrections or source movement if the sample cannot be measured at the calibration distance. 4 refs., 7 figs., 2 tabs.

Camp, D.C.; Gunnink, R.; Ruhter, W.D.; Prindle, A.L.; Gomes, R.J.

1986-10-24

246

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

247

GAUSS IX: An interactive program for the analysis of gamma-ray spectra from Ge semiconductor detectors  

SciTech Connect

The newest member of a series of computer programs developed at the INEL for analysis of gamma-ray spectra from Ge semiconductor detectors is GAUSS IX. Tis program makes use of the computational routines of GAUSS VII in an interactive structure. The interactive features are implemented with OSF/Motif and the X Window System. This interactive version can dramatically decrease the turnaround time for spectral analyses, especially when the user needs to refit some of the peaks with specially-chosen fitting parameters. The graphic features increase the opportunity for detecting patterns and anomalies in the spectral analyses. The user of this program can set up the analysis parameters (i.e., peaks, peak regions, etc.) interactively via window dialogs. The user can interactively display and review the results, selectively re-fit peaks, and save or purge the results, as appropriate. The spectral displays can include the spectral data, peak locations, peak fitting regions, fit curves, and background curves; and the display is completely zoomable, scrollable, and resizable.

Egger, A.E.; Putnam, M.H.; Helmer, R.G.; Caffrey, A.J.; Greenwood, R.C. [Idaho National Engineering Lab., Idaho Falls, ID (United States)] [Idaho National Engineering Lab., Idaho Falls, ID (United States)

1995-08-01

248

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

249

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

250

Absorption-Mode Fourier Transform Mass Spectrometry: The Effects of Apodization and Phasing on Modified Protein Spectra  

NASA Astrophysics Data System (ADS)

The method of phasing broadband Fourier transform ion cyclotron resonance (FT-ICR) spectra allows plotting the spectra in the absorption-mode; this new approach significantly improves the quality of the data at no extra cost. Herein, an internal calibration method for calculating the phase function has been developed and successfully applied to the top-down spectra of modified proteins, where the peak intensities vary by 100×. The result shows that the use of absorption-mode spectra allows more peaks to be discerned within the recorded data, and this can reveal much greater information about the protein and modifications under investigation. In addition, noise and harmonic peaks can be assigned immediately in the absorption-mode.

Qi, Yulin; Li, Huilin; Wills, Rebecca H.; Perez-Hurtado, Pilar; Yu, Xiang; Kilgour, David P. A.; Barrow, Mark P.; Lin, Cheng; O'Connor, Peter B.

2013-06-01

251

Absorption-Mode Fourier Transform Mass Spectrometry: the Effects of Apodization and Phasing on Modified Protein Spectra  

PubMed Central

The method of phasing broadband FT-ICR spectra allows plotting the spectra in the absorption-mode; this new approach significantly improves the quality of the data at no extra cost. Herein, an internal calibration method for calculating the phase function has been developed, and successfully applied to the top-down spectra of modified proteins, where the peak intensities vary by >100×. The result shows that the use of absorption-mode spectra allows more peaks to be discerned within the recorded data, and this can reveal much greater information about the protein and modifications under investigation. In addition, noise and harmonic peaks can be assigned immediately in the absorption-mode.

Qi, Yulin; Li, Huilin; Wills, Rebecca H.; Perez-Hurtado, Pilar; Yu, Xiang; Kilgour, David. P. A.; Barrow, Mark P.; Lin, Cheng; O'Connor, Peter B.

2014-01-01

252

PC/FRAM: New capabilities for the gamma-ray spectrometry measurement of plutonium isotopic composition  

SciTech Connect

We describe the new capability of and.present measurement results from the PC/FRAM plutonium isotopic analysis code. This new code allows data acquisition from a single coaxial germanium detector and analysis over an energy range from 120 keV to above I MeV. For the first time we demonstrate a complete isotopic analysis using only gamma rays greater than 200 keV in energy. This new capability allows the measurement of the plutonium isotopic composition of items inside shielded or heavy-walled containers without having to remove the items from the container. This greatly enhances worker safety by reducing handling and the resultant radiation exposure. Another application allows international inspectors to verify the contents of items inside sealed, long-term storage containers that may not be opened for national security or treaty compliance reasons. We present measurement results for traditional planar germanium detectors as well as coaxial detectors measuring shielded and unshielded samples.

Sampson, T.E.; Kelley, T.A.; Cremers, T.L.; Konkel, T.R.; Friar, R.J.

1995-10-01

253

Radiometric analysis of construction materials using HPGe gamma-ray spectrometry.  

PubMed

Concentrations of primordial radionuclides in common construction materials collected from the south-west coastal region of India were determined using a high-purity germanium gamma-ray spectrometer. Average specific activities (Bq kg(-1)) for (238)U((226)Ra) in cement, brick, soil and stone samples were obtained as 54 ± 13, 21 ± 4, 50 ± 12 and 46 ± 8, respectively. Respective values of (232)Th were obtained as 65 ± 10, 21 ± 3, 58 ± 10 and 57 ± 12. Concentrations of (40)K radionuclide in cement, brick, soil and stone samples were found to be 440 ± 91, 290 ± 20, 380 ± 61 and 432 ± 64, respectively. To evaluate the radiological hazards, radium equivalent activity, various hazard indices, absorbed dose rate and annual effective dose have been calculated, and compared with the literature values. Obtained data could be used as reference information to assess any radiological contamination due to construction materials in future. PMID:22887119

Khandaker, M U; Jojo, P J; Kassim, H A; Amin, Y M

2012-11-01

254

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

255

Effect of gamma radiation on thermal decomposition, X-ray diffraction and electronic spectra of nickel (II) complexes of diethylene triamine, pyridine and 2-amino pyridine  

NASA Astrophysics Data System (ADS)

Thermal behaviour, X-ray diffraction and electronic spectra of nickel (II) complexes of diethylene triamine, pyridine and 2-amino pyridine were studied before and after gamma irradiation. Irradiation enhanced thermal decomposition of the complexes, lowering activation energy, frequency factor and entropy of activation. From X-ray diffraction studies, unirradiated and irradiated complexes are found to be orthorhombic. Irradiation changed the lattice parameters. The parameters Dq, B' and ? were calculated from the UV-visible spectra of the complexes. Irradiation decreased LFSE (10 Dq) and increased Racah parameter B' and the covalency factor ? of the complexes except in nickel (II) complex of diethylenetriamine where the effect of irradiation is insignificant.

Krishnan, G.; Jayashri, T. A.; Devi, K. Geetha

2009-03-01

256

Updated summary of measurements and calculations of neutron and gamma-ray emission spectra from spheres pusled with 14-MeV neutrons: Revision 1  

SciTech Connect

New measurements of the neutron and gamma-ray emission spectra from materials of interest to thermonuclear reactors with a 14 MeV neutron source were done during 1986 and 1987. These measurements characterized by better resolution than those reported in the Summary published in 1982, were performed using the pulsed sphere and time-of-flight techniques. The detector used in these measurements was a NE-213 cylinder, 5.08 cm in diameter by 5.08 cm thick. The new measurements include the following materials: Be, C, N, H/sub 2/O, C/sub 2/F/sub 4/ (teflon), Al, Si, Ti, Fe, Cu, Ta, W, Au, Pb, /sup 232/Th, and /sup 238/U. For all these materials, both the neutron and gamma emission spectra were measured. A complete tabulation of all the measurements done under the Pulse Sphere Program is presented. 37 refs., 1 tab.

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

1989-01-19

257

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

258

Martian surface heat production and crustal heat flow from Mars Odyssey Gamma-Ray spectrometry  

NASA Astrophysics Data System (ADS)

Martian thermal state and evolution depend principally on the radiogenic heat-producing element (HPE) distributions in the planet's crust and mantle. The Gamma-Ray Spectrometer (GRS) on the 2001 Mars Odyssey spacecraft has mapped the surface abundances of HPEs across Mars. From these data, we produce the first models of global and regional surface heat production and crustal heat flow. As previous studies have suggested that the crust is a repository for approximately 50% of the radiogenic elements on Mars, these models provide important, directly measurable constraints on Martian heat generation. Our calculations show considerable geographic and temporal variations in crustal heat flow, and demonstrate the existence of anomalous heat flow provinces. We calculate a present day average surface heat production of 4.9 ± 0.3 × 10-11 W · kg-1. We also calculate the average crustal component of heat flow of 6.4 ± 0.4 mW · m-2. The crustal component of radiogenically produced heat flow ranges from <1 mW · m-2 in the Hellas Basin and Utopia Planitia regions to ˜13 mW · m-2 in the Sirenum Fossae region. These heat production and crustal heat flow values from geochemical measurements support previous heat flow estimates produced by different methodologies.

Hahn, B. C.; McLennan, S. M.; Klein, E. C.

2011-07-01

259

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  

NASA Astrophysics Data System (ADS)

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 spectra; (2) within the most useful range of ?CH, ?C?O,?C?N and ?NH vibrations, MINDO3 provides the best linearity between the calculated and experimental wavenumbers. The possibility of IR spectral discrimination of diastereomers for the case of derivatives of optically active amino acids has also been considered. IR spectra simulations using the PM3 method for various diastereomers of alanine derivative 2,5,7,10-tetramethylhexahydroimidazo[1,2-a]imidazo-[1,2-d]pyrazine-3,8-dione have shown the ?C?O and ?C?N frequencies to vary insignificantly, by less than 8 cm -1, thus making spectral discrimination of the diastereomers impossible under normal optical resolution of the commercially available FTIR detectors.

Basiuk, Vladimir A.

1999-02-01

260

Ultraviolet and infrared absorption spectra of Cr2O3 doped - Sodium metaphosphate, lead metaphosphate and zinc metaphosphate glasses and effects of gamma irradiation: A comparative study  

NASA Astrophysics Data System (ADS)

The effects of gamma irradiation on spectral properties of Cr2O3-doped phosphate glasses of three varieties, namely sodium metaphosphate, lead metaphosphate and zinc metaphosphate have been investigated. Optical spectra of the undoped samples reveal strong UV absorption bands which are attributed to the presence of trace iron impurities in both the sodium and zinc phosphate glasses while the lead phosphate glass exhibits broad UV near visible bands due to combined absorption of both trace iron impurities and divalent lead ions. The effect of chromium oxide content has been investigated. The three different Cr2O3-doped phosphate glasses reveal spectral visible bands varying in their position and intensity and splitting due to the different field strengths of the Na+, Pb2+, Zn2+ cations, together with the way they are housed in the network and their effects on the polarisability of neighboring oxygens ligands. The effects of gamma irradiation on the optical spectral properties of the various glasses have been compared. The different effects for lead and zinc phosphate are related to the ability of Pb2+, and Zn2+ to form additional structural units causing stability of the network towards gamma irradiation. Also, the introduction of the transition metal chromium ions reveals some shielding behavior towards irradiation. Infrared absorption spectra of the three different base phosphate glasses show characteristic vibrations due to various phosphate groups depending on the type of glass and Cr2O3 is observed to slightly affect the IR spectra. Gamma irradiation causes minor variations in some of the intensities of the IR spectra but the main characteristic bands due to phosphate groups remain in their number and position.

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

2013-10-01

261

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

262

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

263

Improvements to alpha-particle spectrometry techniques.  

PubMed

Improvements to the conventional methods for alpha-particle spectrometry measurement and analysis have recently been implemented in our laboratory. They include the application of corrections for energy drift in long-duration measurements, the development and application of an efficient deconvolution method for complex alpha spectra using the new computer code ALFITeX, an alpha-gamma coincidence system using a dual-parameter multichannel analyzer, and the digitization of this coincidence system. PMID:24315085

Caro Marroyo, B; Martín Sánchez, A; Jurado Vargas, M

2014-05-01

264

A method to estimate a contribution of Ge(n,n?) reaction to the low-energy part of gamma spectra of HPGe detectors  

NASA Astrophysics Data System (ADS)

Long-time background spectra of a well-shielded HPGe detector are recorded in order to estimate the contribution of inelastic neutron scattering on Ge nuclei in the low-energy part of the spectra, mainly influenced by elastic neutron collisions. It is shown that using intensities of several asymmetric peaks characteristic of Ge(n,n') reactions and some properties of detectors (ability for total absorption or total transmission of gamma photons emitted during de-excitation of Ge nuclei) the contribution of Ge(n,n') reactions to the low-energy part of spectra can be evaluated. The obtained result is in good agreement with results of simulations available in the literature.

Krmar, M.; Hansman, J.; Jovan?evi?, N.; Lalovi?, N.; Slivka, J.; Jokovi?, D.; Maleti?, D.

2013-05-01

265

180Hf energy levels deduced from thermal and average resonance neutron-capture gamma-ray spectra  

Microsoft Academic Search

An energy level diagram for 180Hf is developed on the basis of neutron-capture gamma-ray spectroscopy. Both thermal neutron capture and average resonance neutron-capture studies were made with isotopically enriched and natural Hf samples. The energies and intensities of the high-energy 7.4-4.7 MeV primary gamma transitions and the intermediate-energy 2.1-0.5 MeV gamma transitions were made with the in-pile (n ,gamma) source

D. L. Bushnell; D. J. Buss; Robert K. Smither

1974-01-01

266

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

267

First-order derivative resolution of overlapped PAH peaks with common mass spectra in gas chromatography-mass spectrometry.  

PubMed

First-order derivative of 15 points smoothed chromatograms of mixtures of benzo(b)fluoranthene (BbF) and benzo(k)fluoranthene (BkF) for the m/z 252 ion obtained using two microscans has been proposed as a simple alternative to the resolution of overlapped chromatographic peaks of these two compounds which have identical mass spectra. The procedure provides limits of detection of 12 and 29ngg(-1) for BbF and BkF, respectively and offers the possibility to use the 250 and 248 ions to confirm the identity of these analytes. PMID:18371704

Quintás, Guillermo; Lendl, Bernhard; Pastor, Agustín; de la Guardia, Miguel

2008-01-15

268

``Discrepant hardenings'' in cosmic ray spectra: A first estimate of the effects on secondary antiproton and diffuse gamma-ray yields  

NASA Astrophysics Data System (ADS)

Recent data from CREAM seem to confirm early suggestions that primary cosmic ray spectra at few TeV/nucleon are harder than in the 10-100 GeV range. Also, helium and heavier nuclei spectra appear systematically harder than the proton fluxes at corresponding energies. We note here that if the measurements reflect intrinsic features in the interstellar fluxes (as opposed to local effects) appreciable modifications are expected in the sub-TeV range for the secondary yields, such as antiprotons and diffuse gamma rays. Presently, the ignorance on the origin of the features represents a systematic error in the extraction of astrophysical parameters as well as for background estimates for indirect dark matter searches. We find that the spectral modifications are appreciable above 100 GeV, and can be responsible for ˜30% effects for antiprotons at energies close to 1 TeV or for gammas at energies close to 300 GeV, compared to currently considered predictions based on simple extrapolation of input fluxes from low-energy data. Alternatively, if the feature originates from local sources, uncorrelated spectral changes might show up in antiproton and high-energy gamma rays, with the latter ones likely dependent from the line of sight.

Donato, Fiorenza; Serpico, Pasquale D.

2011-01-01

269

SOFT GAMMA-RAY SPECTRA EMITTED AFTER CAPTURE OF THERMAL NEUTRONS BY Cu⁶³, Cu⁶⁵, Ag¹°⁷, Ag¹°⁹ AND In¹¹⁵  

Microsoft Academic Search

A scintillation spectrometer with NaI(Tl) crystal was used for measuring ; the spectra of soft gamma rays produced by a thermal neutron capture in divided ; targets of isotopes of copper, silver, and indium and natural silver and copper. ; The values of gamma -ray intensities of the latter are in good agreement with ; the results obtained for targets

V. V. Sklyarevskii; E. P. Stepanov; B. A. Obinyakov

1958-01-01

270

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

271

Methods for spectral interference corrections for direct measurements of 234U and 230Th in materials by gamma-ray spectrometry.  

PubMed

When the high-resolution gamma-ray spectrometry was used in the analysis of (234)U and (230)Th in samples, there is a much more need to correct for the measured activity results of (234)U and (230)Th mainly due to self-absorption effects and the interfering lines from (226)Ra, (235)U, (238)U and their decay products that often might be present in the samples. Therefore, in the present study, the methods for the spectral interference corrections for the analytical peaks of (234)U and (230)Th are suggested to take into account the contributions of the overlapping gamma rays to these peaks. For the method validation, direct gamma-ray spectrometric measurements were carried out using certified reference materials (CRM) by use of a 76.5 % n-type Ge detector. The activities measured for the CRM samples were corrected for spectral interferences, self-absorption and true coincidence-summing (TCS) effects. The obtained results indicate that ignoring of the contribution of the interference gamma rays to the main analytical peak at 53.2 keV of (234)U leads to a lager systematic error of 87.3-90.4 % for the measured activities of (234)U, and similarly if one ignores the contributions of the interference gamma rays to the main analytical peak at 67.7 keV of (230)Th, this leads to a much smaller systematic error of 2.1-2.7 % for the activities of (230)Th. Therefore, the required correction factors for spectral interferences to the analytical peaks of (234)U and (230)Th are not negligible and thus they should also be considered besides necessary self-absorption factors to determine more accurate activities in the samples. On the other hand, it is estimated that although the TCS effects on the main analytical peaks of both (234)U and (230)Th are negligibly small, those TCS correction factors for their interference gamma rays to these peaks should be taken into account when direct measurements are performed in a close-counting geometry condition. Otherwise, the resulted activities can have serious erroneous results for both (234)U and (230)Th while using gamma-ray spectrometry, thereby leading to inaccuracies in their derived quantities, for instance, the corresponding age determinations of the samples. PMID:19843544

Yücel, H; Solmaz, A N; Köse, E; Bor, D

2010-03-01

272

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

273

Statistical properties of gamma-ray spectra obtained with loss-free or zero-dead-time counting, and ORTEC'S ``variance spectrum''  

NASA Astrophysics Data System (ADS)

In the "dual spectrum" approach to non-Poisson counting statistics of gamma-ray spectra obtained with loss-free or zero-dead-time (ZDT) counting, an uncorrected spectrum acquired in parallel is employed to obtain the uncertainties in the dead-time-corrected spectrum. In this paper, it is mathematically proved that this approach can only yield correct results under very special conditions. It is also proved that a variance spectrum acquired by adding the squares of the increments added to the dead-time-corrected spectrum do provide the correct variances in a loss-free or ZDT spectrum.

Blaauw, Menno; Fleming, Ronald F.

2003-06-01

274

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

275

Multi-group approximation, scattering and calibration coefficients, uncertainty estimates and detection limits of a NaI(Tl)-based gamma spectrometry set-up for low-level activity analysis  

Microsoft Academic Search

This paper describes a quantitative radioactivity analysis method especially suitable for environmental samples with low-level activity. The method, consisting of a multi-group approximation based on total absorption and Compton spectra of gamma rays, is coherently formalized and a computer algorithm thereof designed to analyze low-level activity NaI(Tl) gamma ray spectra of environmental samples. Milk powder from 1988 was used as

Ateba P. Owono

2010-01-01

276

Building an empirical mass spectra library for screening of organic pollutants by ultra-high-pressure liquid chromatography/hybrid quadrupole time-of-flight mass spectrometry.  

PubMed

Hybrid quadrupole time-of-flight mass spectrometry (QTOF MS) has gained wide acceptance in many fields of chemistry, for example, proteomics, metabolomics and small molecule analysis. This has been due to the numerous technological advances made to this mass analyser in recent years. In the environmental field, the instrument has proven to be one of the most powerful approaches for the screening of organic pollutants in different matrices due to its high sensitivity in full acquisition mode and mass accuracy measurements. In the work presented here, the optimum experimental conditions for the creation of an empirical TOF MS spectra library have been evaluated. For this model we have used a QTOF Premier mass spectrometer and investigated its functionalities to obtain the best MS data, mainly in terms of mass accuracy, dynamic range and sensitivity. Different parameters that can affect mass accuracy, such as lock mass, ion abundance, spectral resolution, instrument calibration or matrix effect, have also been carefully evaluated using test compounds (mainly pesticides and antibiotics). The role of ultra-high-pressure liquid chromatography (UHPLC), especially when dealing with complex matrices, has also been tested. In addition to the mass accuracy measurements, this analyser allows the simultaneous acquisition of low and high collision energy spectra. This acquisition mode greatly enhances the reliable identification of detected compounds due to the useful (de)protonated molecule and fragment ion accurate mass information obtained when working in this mode. An in-house empirical spectral library was built for approximately 230 organic pollutants making use of QTOF MS in MS(E) mode. All the information reported in this paper is made available to the readers to facilitate screening and identification of relevant organic pollutants by QTOF MS. PMID:21192031

Díaz, Ramón; Ibáñez, María; Sancho, Juan V; Hernández, Félix

2011-01-30

277

Cyclodextrin--piroxicam inclusion complexes: analyses by mass spectrometry and molecular modelling  

NASA Astrophysics Data System (ADS)

Mass spectrometry has been used to investigate the natures of non-covalent complexes formed between the anti-inflammatory drug piroxicam and [alpha]-, [beta]- and [gamma]-cyclodextrins. Energies of these complexes have been calculated by means of molecular modelling. There is a correlation between peak intensities in the mass spectra and the calculated energies.

Gallagher, Richard T.; Ball, Christopher P.; Gatehouse, Deborah R.; Gates, Paul J.; Lobell, Mario; Derrick, Peter J.

1997-11-01

278

Measurement of Radionuclides and Gamma-Ray Dose Rate in Soil and Transfer of Radionuclides from Soil to Vegetation, Vegetable of Some Northern Area of Pakistan Using ?-Ray Spectrometry  

Microsoft Academic Search

The analysis of gamma emitters natural radionuclides, i.e., 226Ra, 232Th, and 40K, has been carried out in soil, vegetation, vegetable, and water samples collected from some Northern area of Pakistan, using\\u000a gamma-ray spectrometry. The ?-ray spectrometry was carried out using high-purity Germanium detector coupled with a computer-based\\u000a high-resolution multi-channel analyzer. The activity concentrations in soil ranges from 24.7 to 78.5 Bq?kg?1,

Hasan M. Khan; M. Ismail; Khalid Khan; Perveen Akhter

2011-01-01

279

Chemometric and multivariate statistical analysis of time-of-flight secondary ion mass spectrometry spectra from complex Cu-Fe sulfides.  

PubMed

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) spectra of mineral samples are complex, comprised of large mass ranges and many peaks. Consequently, characterization and classification analysis of these systems is challenging. In this study, different chemometric and statistical data evaluation methods, based on monolayer sensitive TOF-SIMS data, have been tested for the characterization and classification of copper-iron sulfide minerals (chalcopyrite, chalcocite, bornite, and pyrite) at different flotation pulp conditions (feed, conditioned feed, and Eh modified). The complex mass spectral data sets were analyzed using the following chemometric and statistical techniques: principal component analysis (PCA); principal component-discriminant functional analysis (PC-DFA); soft independent modeling of class analogy (SIMCA); and k-Nearest Neighbor (k-NN) classification. PCA was found to be an important first step in multivariate analysis, providing insight into both the relative grouping of samples and the elemental/molecular basis for those groupings. For samples exposed to oxidative conditions (at Eh ~430 mV), each technique (PCA, PC-DFA, SIMCA, and k-NN) was found to produce excellent classification. For samples at reductive conditions (at Eh ~ -200 mV SHE), k-NN and SIMCA produced the most accurate classification. Phase identification of particles that contain the same elements but a different crystal structure in a mixed multimetal mineral system has been achieved. PMID:22324886

Kalegowda, Yogesh; Harmer, Sarah L

2012-03-20

280

Identification of differentially expressed proteins of gamma-ray irradiated rat intestinal epithelial IEC-6 cells by two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionisation-time of flight mass spectrometry.  

PubMed

To identify proteins involved in the processes of cellular and molecular response to radiation damage repair in intestinal epithelial IEC-6 cells, we comparatively analyzed the proteome of irradiated IEC-6 cells with that of normal cells. A series of methods were used, including two-dimensional gel electrophoresis (Z-DE), PDQuest software analysis of 2-DE gels, peptide mass fingerprinting based on matrix-assisted laser desorption/ionisation-time of flight-mass spectrometry (MALDI-TOF-MS), and Swiss-Prot database searching, to separate and identify differentially expressed proteins. Western blotting and reverse transcriptase polymerase chain reaction (RT-PCR) were used to validate the differentially expressed proteins. Image analysis revealed that averages of 608 +/- 39 and 595 +/- 31 protein spots were detected in normal and irradiated IEC-6 cells, respectively. Sixteen differential protein spots were isolated from gels, and measured with MALDI-TOF-MS. A total of 14 spots yielded good spectra, and 11 spots matched with known proteins after database searching. These proteins were mainly involved in anti-oxidation, metabolism, and protein post-translational processes. Western blotting confirmed that stress-70 protein was down-regulated by gamma-irradiation. Up-regulation of ERP29 was confirmed by RT-PCR, indicating that it is involved in ionizing radiation. The clues provided by the comparative proteome strategy utilized here will shed light on molecular mechanisms of radiation damage repair in intestinal epithelial cells. PMID:15700242

Bo, Zhang; Yongping, Su; Fengchao, Wang; Guoping, Ai; Yongjiang, Wei

2005-02-01

281

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.

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

282

An evaluation of commercial IBM PC software for the analysis of low-level environmental gamma-ray spectra  

Microsoft Academic Search

A comparative evaluation of seven commercial gamma-ray analysis software packages, written for the IBM PC, was performed. Four software packages were supplied by US nuclear instrument manufacturers. A fifth package was supplied by a French nuclear instrument manufacturer. Two additional packages were supplied by software companies in the United States and Finland. For this evaluation emphasis was given to accuracy,

C SANDERSON

1988-01-01

283

A computer program for the identification of nuclides by using median estimates of peak areas in gamma-ray spectra  

Microsoft Academic Search

For a set of a priori given nuclides taken from a work library, the computer program DIMEN, presented in this paper, uses median estimates of the peak areas and estimates of their errors to produce a list of possible nuclides matching a gamma-line and some measure of the reliability of this assignment. A Gaussian peak shape is used to analyze

V. S. Kondrashov; Z. D. Moroz; A. A. Kolyshkin; Rémi Vaillancourt

1993-01-01

284

0-600 kev GAMMA-RAY SPECTRA FROM THERMAL NEUTRON CAPTURE IN THE REGION A = 104 TO 198  

Microsoft Academic Search

The energies and absolute intensities of prominent peaks in the 0-600 ; kev region of the gamma-ray spectrum following thermal neutron capture have been ; measured with a single NaI(T1) scintillation spectrometer. The elements ; investigated were rhodium, silver, cadmium, indium, antimony, tellurium, iodine, ; samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ; hafnium, tantalum, rhenium, iridium, platinum, and

James Draper

1959-01-01

285

0-600 kev Gamma-Ray Spectra from Thermal Neutron Capture in the Region A=104 to 198  

Microsoft Academic Search

The energies and absolute intensities of prominent peaks in the 0-600 kev region of the gamma-ray spectrum following thermal neutron capture have been measured with a single NaI(Tl) scintillation spectrometer. The elements investigated were rhodium, silver, cadmium, indium, antimony, tellurium, iodine, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, hafnium, tantalum, rhenium, iridium, platinum, and gold.

James E. Draper

1959-01-01

286

Low-Temperature Optical Spectra and Zero-Phonon Transitions of Color Centers in gamma-Rayed Sodium Fluoride Crystals  

Microsoft Academic Search

A lot of narrow lines on R2, R+, N1, N- and some other unknown centers have been observed in gamma-rayed pure and doped sodium fluoride crystals in the temperature range of 9-77 K. The proper laser irradiation was used for strengthening the zero-phonon lines and the relative explanation was given. The spectral properties and thermostabilities of the lines were investigated

Hongen Gu

1993-01-01

287

Ion suppression effects in liquid chromatography–electrospray-ionisation transport-region collision induced dissociation mass spectrometry with different serum extraction methods for systematic toxicological analysis with mass spectra libraries  

Microsoft Academic Search

Ion suppression effects during electrospray-ionsation mass spectrometry (ESI-MS) caused by different sample preparation procedures for serum were investigated. This topic is of importance for systematic toxicological analysis for which LC–ESI-MS has been developed with transport-region collision-induced dissociation (ECI-CID) and mass spectra library searching. With continuous postcolumn infusion of two test compounds—codeine and glafenine—the ion suppression effects of extracted biological matrix

Claudia Müller; Patrick Schäfer; Mylène Störtzel; Susanne Vogt; Wolfgang Weinmann

2002-01-01

288

Spectral interference corrections for the measurement of (238)U in materials rich in thorium by a high resolution gamma-ray spectrometry.  

PubMed

In this study, the spectral interferences are investigated for the analytical peaks at 63.3 keV of (234)Th and 1001.0 keV of (234m)Pa, which are often used in the measurement of (238)U activity by the gamma-ray spectrometry. The correction methods are suggested to estimate the net peak areas of the gamma-rays overlapping the analytical peaks, due to the contribution of (232)Th that may not be negligible in materials rich in natural thorium. The activity results for the certified reference materials (CRMs) containing U and Th were measured with a well type Ge detector. The self-absorption and true coincidence-summing (TCS) effects were also taken into account in the measurements. It is found that ignoring the contributions of the interference gamma-rays of (232)Th and (235)U to the mixed peak at 63.3 keV of (234)Th ((238)U) leads to the remarkably large systematic influence of 0.8-122% in the measured (238)U activity, but in case of ignoring the contribution of (232)Th via the interference gamma-ray at 1000.7 keV of (228)Ac to the mixed peak at 1001 keV of (234m)Pa ((238)U) results in relatively smaller systematic influence of 0.05-3%, depending on thorium contents in the samples. The present results showed that the necessary correction for the spectral interferences besides self-absorption and TCS effects is also very important to obtain more accurate (238)U activity results. Additionally, if one ignores the contribution of (232)Th to both (238)U and (40)K activities in materials, the maximum systematic influence on the effective radiation dose is estimated to be ~6% and ~1% via the analytical peaks at 63.3 and 1001 keV for measurement of the (238)U activity, respectively. PMID:19683454

Yücel, H; Solmaz, A N; Köse, E; Bor, D

2009-11-01

289

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.

2013-08-01

290

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

291

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

292

Regional radiometric study over the east of Homs City depending on carborne gamma-ray spectrometry survey.  

National Technical Information Service (NTIS)

The purpose of regional carborne gamma-ray survey over the east of Homs city is to determine the ground concentration of potassium, uranium and thorium. In the other hand, collecting essential information for future monitoring of any suspected leakage or ...

M. Aissa

1994-01-01

293

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

294

A nondestructive method based on gamma spectrometry for the measurements of plutonium hold-up or plutonium wastes  

Microsoft Academic Search

With respect to in-plant holdup and wastes, plutonium quantities are measured in most cases by nondestructive methods such as neutron counting, gamma-photon counting, and infrared detection. These methods are often imperfect for various reasons: difficult access to sample, highly radioactive background, screens, etc. It is therefore of interest to develop other methods in order to check the results from these

J. Morel; B. Chauvenet; M. Etcheverry; L. Louppe; J. Monier

1987-01-01

295

Pulsational variability of Li I 6708 Åline profile in the spectra of roAp star gamma Equ  

NASA Astrophysics Data System (ADS)

In the framework of the Project "Lithium in CP stars" the task of pulsational line profile variations (LPV) for Li I 6708 Å is carried out. The high spectral and time resolution observations were obtained for typical roAp(CP2) star gamma Equ. Analysis of two night's observations shows a definite blue-to-red LPV of Li I 6708 A during pulsational period, that could be explained by two ways: the first supposes the formation of shock wave in the most upper layers near magnetic poles and red shifts due to matter falling on star; the second - a red asymmetry of Li I line profile is explained by high isotopic ratio 6Li/7Li (about 0.5) due to spallation processes in polar Li spot.

Shavrina, A.; Polosukhina, N.; Khan, S.; Pavlenko, Ya.; Kudryavtsev, D.; Mikhailitska, N.; Lyubchik, Yu.; Ilyin, I.

296

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

297

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

298

Determination of soil depth profiles for 137 Cs and 210 Pb using gamma-ray spectrometry with Compton suppression  

Microsoft Academic Search

Summary  137Cs and to a lesser extent, 210Pb have been widely used for soil erosion and sedimentation studies. The accuracy of their quantification is greatly dependent on the proper handling of the sources of error that may affect the results. These include ambient background variation, attenuation for the 210Pb 45 keV gamma-photons in the sample, efficiency calibration and large statistical errors

S. Landsberger

2005-01-01

299

Determination of the natural radioactivity levels in north west of Dukhan, Qatar using high-resolution gamma-ray spectrometry.  

PubMed

This study is aimed at the determination of the activity concentrations of naturally occuring and technologically enhanced levels of radiation in 34 representative soil samples that have been collected from an inshore oil field area which was found to have, in a previous study, the highest observed value of 226Ra concentration among 129 soil samples. The activity concentrations of 238U and 226Ra have been inferred from gamma-ray transitions associated with their decay progenies and measured using a hyper-pure germanium detector. Details of the sample preparation and the gamma-ray spectroscopic analysis techniques are presented, together with the values of the activity concentrations associated with the naturally occuring radionuclide chains for all the samples collected from NW Dukhan. Discrete-line, gamma-ray energy transitions from spectral lines ranging in energy from ?100 keV up to 2.6 MeV have been associated with characteristic decays of the various decay products within the 235.8U and 232Th radioactive decay chains. These data have been analyzed, under the assumption of secular equilibrium for the U and Th decay chains. Details of the sample preparation and the gamma-ray spectroscopic analysis techniques are presented. The weighted mean value of the activity concentrations of 226Ra in one of the samples was found to be around a factor of 2 higher than the values obtained in the previous study and approximately a factor of 10 higher than the accepted worldwide average value of 35 Bq/kg. The weighted mean values of the activity concentrations of 232Th and 40K were also deduced and found to be within the worldwide average values of 30 and 400 Bq/kg, respectively. Our previous study reported a value of 201.9±1.5Stat.±13Syst.Bq/kg for 226Ra in one sample and further investigation in the current work determined a measured value for 226Ra of 342.00±1.9Stat.±25Syst.Bq/kg in a sample taken from the same locality. This is significantly higher than all the other investigated soil samples in the current and previous works. Notably, the Th levels in the same sample are within the worldwide average expectations, implying that the increased 226Ra concentration arises from TENORM processes. PMID:22244196

Al-Sulaiti, Huda; Nasir, Tabassum; Al Mugren, K S; Alkhomashi, N; Al-Dahan, N; Al-Dosari, M; Bradley, D A; Bukhari, S; Matthews, M; Regan, P H; Santawamaitre, T; Malain, D; Habib, A

2012-07-01

300

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

2006-07-20

301

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

302

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

303

On the accuracy of determination of fluxes and energy spectra of primary gamma rays by a single imaging atmospheric Cherenkov telescope  

Microsoft Academic Search

The strong energy dependence of the detection efficiency of gamma -rays by imaging atmospheric Cherenkov telescopes (IACT) both at the hardware and software levels, leads to significant uncertainties in the estimate of primary gamma -ray fluxes. Nevertheless, detailed Monte Carlo calculations of the principal characteristics of IACTS, in particular of collection areas and of the gamma \\/proton separation efficiency, allow

F. Aharonian; W. Hofmann; A. Konopelko; A. Plyasheshnikov; M. Ulrich

1995-01-01

304

Determination of gamma-hydroxybutyric acid in human urine by capillary electrophoresis with indirect UV detection and confirmation with electrospray ionization ion-trap mass spectrometry.  

PubMed

Gamma-hydroxybutyric acid (GHB), a minor metabolite or precursor of gamma-aminobutyric acid (GABA), acts as a neurotransmitter/neuromodulator via binding to GABA receptors and to specific presynaptic GHB receptors. Based upon the stimulatory effects, GHB is widely abused. Thus, there is great interest in monitoring GHB in body fluids and tissues. We have developed an assay for urinary GHB that is based upon liquid-liquid extraction and capillary zone electrophoresis (CZE) with indirect UV absorption detection. The background electrolyte is composed of 4 mM nicotinic acid (compound for indirect detection), 3 mM spermine (reversal of electroosmosis) and histidine (added to reach a pH of 6.2). Having a 50 microm I.D. capillary of 40 cm effective length, 1-octanesulfonic acid as internal standard, solute detection at 214 nm and a diluted urine with a conductivity of 2.4 mS/cm, GHB concentrations > or = 2 microg/ml can be detected. Limit of detection (LOD) and limit of quantitation (LOQ) were determined to be dependent on urine concentration and varied between 2-24 and 5-60 microg/ml, respectively. Data obtained suggest that LOD and LOQ (both in microg/ml) can be estimated with the relationships 0.83 kappa and 2.1 kappa, respectively, where kappa is the conductivity of the urine in mS/cm. The assay was successfully applied to urines collected after administration of 25 mg sodium GHB/kg body mass. Negative electrospray ionization ion-trap tandem mass spectrometry was used to confirm the presence of GHB in the urinary extract via selected reaction monitoring of the m/z 103.1-->m/z 85.1 precursor-product ion transition. Independent of urine concentration, this approach meets the urinary cut-off level of 10 microg/ml that is required for recognition of the presence of exogenous GHB. Furthermore, data obtained with injection of plain or diluted urine indicate that CZE could be used to rapidly recognize GHB amounts (in microg/ml) that are > or = 4 kappa. PMID:12685588

Baldacci, Andrea; Theurillat, Regula; Caslavska, Jitka; Pardubská, Helena; Brenneisen, Rudolf; Thormann, Wolfgang

2003-03-21

305

A parametric model to describe neutron spectra around high-energy electron accelerators and its application in neutron spectrometry with Bonner Spheres  

NASA Astrophysics Data System (ADS)

Due to the increased interest of the scientific community in the applications of synchrotron light, there is an increasing demand of high-energy electron facilities, testified by the construction of several new facilities worldwide. The radiation protection around such facilities requires accurate experimental methods to determine the dose due to prompt radiation fields. Neutron fields, in particular, are the most complex to measure, because they extend in energy from thermal (10 -8 MeV) up to hundreds MeV and because the responses of dosemeters and survey meters usually have large energy dependence. The Bonner Spheres Spectrometer (BSS) is in practice the only instrument able to respond over the whole energy range of interest, and for this reason it is frequently used to derive neutron spectra and dosimetric quantities in accelerator workplaces. Nevertheless, complex unfolding algorithms are needed to derive the neutron spectra from the experimental BSS data. This paper presents a parametric model specially developed for the unfolding of the experimental data measured with BSS around high-energy electron accelerators. The work consists of the following stages: (1) Generation with the FLUKA code, of a set of neutron spectra representing the radiation environment around accelerators with different electron energies; (2) formulation of a parametric model able to describe these spectra, with particular attention to the high-energy component (>10 MeV), which may be responsible for a large part of the dose in workplaces; and (3) implementation of this model in an existing unfolding code.

Bedogni, Roberto; Pelliccioni, Maurizio; Esposito, Adolfo

2010-03-01

306

Capture cross sections and gamma-ray spectra from the interaction of 0. 5- to 3. 0-MeV neutrons with nuclei in the mass range A = 63 to 209  

SciTech Connect

Absolute neutron capture cross sections for natural elements of copper, yttrium, zirconium, niobium, lanthanum, gadolinium, terbium, tantalum, tungsten, rhenium, platinum, thallium, bismuth, and separated isotopes of /sup 63/Cu, /sup 65/Cu, /sup 155/Gd, /sup 157/Gd, /sup 158/Gd, /sup 160/Gd, /sup 182/W, /sup 183/W, /sup 184/W, /sup 186/W, /sup 203/Tl, /sup 205/Tl have been measured in the 0.5- to 3.0-MeV energy range. For most of these nuclides and isotopes, available data were scarce and discrepant, especially for neutron energies above 0.7 MeV. A spectrum-fitting method was developed to deduce the radiative capture cross section from prompt gamma rays emitted by the sample. The gamma rays were recorded by a NaI scintillator surrounded by an annular detector and the capture gamma-ray spectrum was obtained by unfolding the observed pulse-height distribution with the response function of the detector. Gamma ray spectra emitted in the capture of 0.5-MeV neutrons as well as the multiplicity of the gamma-ray transmissions are presented.

Voignier, J.; Joly, S.; Grenier, G.

1986-05-01

307

Gamma-spectrometric measurements of natural-radionuclide contents in soil and gamma dose rates in Yangjiang, PR China  

NASA Astrophysics Data System (ADS)

The average concentration of natural radionuclides in a high-radiation-background area and a control area in Yangjiang and the Enping county of the province Guangdong, PR China, have been measured by in-situ gamma spectrometry and by sampling analysis in our laboratory. Average data on surface and depth distributions in soil have been obtained. The exposure rates to the environmental gamma-radiation field in both areas have been calculated from in-situ gamma spectra with Beck's conversion factor and by the method of total spectrum energy. The averaged total absorbed dose rates, including the cosmic-ray contribution obtained from in-situ gamma spectroscopy, are (18.2 ± 5.0) × 10 -8 and (6.6 ± 1.2) × 10 -8 Gy/h in the high-background and control areas, respectively.

Daling, Luo; Chunxiang, Zhang; Zujie, Guan; Xian, Lai; Guorong, Huang

1990-12-01

308

Purification of pharmaceutical preparations using thin-layer chromatography to obtain mass spectra with Direct Analysis in Real Time and accurate mass spectrometry.  

PubMed

Forensic analysis of pharmaceutical preparations requires a comparative analysis with a standard of the suspected drug in order to identify the active ingredient. Purchasing analytical standards can be expensive or unattainable from the drug manufacturers. Direct Analysis in Real Time (DART™) is a novel, ambient ionization technique, typically coupled with a JEOL AccuTOF™ (accurate mass) mass spectrometer. While a fast and easy technique to perform, a drawback of using DART™ is the lack of component separation of mixtures prior to ionization. Various in-house pharmaceutical preparations were purified using thin-layer chromatography (TLC) and mass spectra were subsequently obtained using the AccuTOF™- DART™ technique. Utilizing TLC prior to sample introduction provides a simple, low-cost solution to acquiring mass spectra of the purified preparation. Each spectrum was compared against an in-house molecular formula list to confirm the accurate mass elemental compositions. Spectra of purified ingredients of known pharmaceuticals were added to an in-house library for use as comparators for casework samples. Resolving isomers from one another can be accomplished using collision-induced dissociation after ionization. Challenges arose when the pharmaceutical preparation required an optimized TLC solvent to achieve proper separation and purity of the standard. Purified spectra were obtained for 91 preparations and included in an in-house drug standard library. Primary standards would only need to be purchased when pharmaceutical preparations not previously encountered are submitted for comparative analysis. TLC prior to DART™ analysis demonstrates a time efficient and cost saving technique for the forensic drug analysis community. Copyright © 2011 John Wiley & Sons, Ltd. PMID:21548141

Wood, Jessica L; Steiner, Robert R

2011-06-01

309

Multi-group approximation, scattering and calibration coefficients, uncertainty estimates and detection limits of a NaI(Tl)-based gamma spectrometry set-up for low-level activity analysis.  

PubMed

This paper describes a quantitative radioactivity analysis method especially suitable for environmental samples with low-level activity. The method, consisting of a multi-group approximation based on total absorption and Compton spectra of gamma rays, is coherently formalized and a computer algorithm thereof designed to analyze low-level activity NaI(Tl) gamma ray spectra of environmental samples. Milk powder from 1988 was used as the example case. Included is a special analysis on the uncertainty estimation. Gamma sensitiveness is defined and numerically evaluated. The results reproduced the calibration data well, attesting to the reliability of the method. The special analysis shows that the uncertainty of the assessed activity is tied to that of the calibration activity data. More than 77% of measured 1461-keV photons of (40)K were counted in the range of clearly lower energies. Pile-up of single line photons ((137)Cs) looks negligible compared to that of a two-line cascade ((134)Cs). The detection limit varies with radionuclide and spectrum region and is related to the gamma sensitiveness of the detection system. The best detection limit always lies in a spectrum region holding a line of the radionuclide and the highest sensitiveness. The most radioactive milk powder sample showed a activity concentration of 21+/-1 Bq g(-1)for (137)Cs, 323+/-13 Bq g(-1) for (40)K and no (134)Cs. PMID:20471729

Owono, Ateba P

2010-09-01

310

IR spectra simulation as auxiliary tool for gas chromatography/Fourier transform IR spectroscopy/mass spectrometry identification of unknown compounds. 2. PM3, AM1, MNDO and MINDO3 simulations for simple nitriles  

NASA Astrophysics Data System (ADS)

A set of the semi-empirical methods (PM3, AM1, MNDO and MINDO3) 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 nitriles, taking 23 relatively simple nitriles as test compounds. Of the four methods, MNDO can be considered as the most advantageous since: (1) for 17 compounds of 23 tested, the IR spectra simulated by this method best match the experimental spectra (and in additional 3 cases, the results are as good as those obtained by AM1 method); (2) within the range of experimental wavenumbers of ˜900-3100 cm -1, MNDO provides the best linearity between the calculated and experimental values (with a correlation coefficient of 0.989). A scaling factor of 0.85 can be used to afford better correspondence between the calculated and experimental wavenumbers. A disadvantage of the MINDO simulations is underestimation of ?C?N (and sometimes ?CH) band intensities.

Basiuk, Vladimir A.

1999-12-01

311

Authenticity assessment of gamma- and delta-decalactone from prunus fruits by gas chromatography combustion/pyrolysis isotope ratio mass spectrometry (GC-C/P-IRMS).  

PubMed

Authenticity assessment of gamma-decalactone (1) and delta-decalactone (2) from peach (Prunus persica var. persica), apricot (Prunus armeniaca), and nectarine (Prunus persica var. nectarina) was performed using gas chromatography-isotope ratio mass spectrometry (GC-IRMS) in the combustion (C) and pyrolysis (P) mode. In addition, commercially available synthetic (nature-identical) 1 and 2 as well as biotechnologically produced samples (declared to be "natural") were characterized by their delta(2)H(V)(-)(SMOW) and delta(13)C(V)(-)(PDB) values. For the Prunus fruits under study, rather narrow ranges of delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW) data of 1, varying from - 34.6 per thousand to - 38.4 per thousand and -160 per thousand to -206 per thousand, respectively, were obtained. Synthetic references of 1 showed delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW) data ranging from -27.4 per thousand to -28.3 per thousand and -151 per thousand to -184 per thousand, respectively. Samples of 1 declared to be "natural" exhibited ranges from -28.1 per thousand to -29.2 per thousand and -192 per thousand to -286 per thousand for delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW), respectively. For 2 from peach, apricot, and nectarine, delta(13)C(V)(-)(PDB) values ranging from -34.0 per thousand to -37.9 per thousand were determined; the delta(2)H(V)(-)(SMOW) values ranged from -171 per thousand to -228 per thousand. The delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW) data for synthetic 2 were -28.2 per thousand and -171 per thousand, respectively, that is, similar to those of 2 from "natural" origin, ranging from -27.7 per thousand to -30.1 per thousand and -185 per thousand to -230 per thousand for delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW), respectively. GC-C/P-IRMS allowed clear-cut analytical differentiation of the synthetic and "ex-plant" origin of 1 and 2, whereas narrow ranges of delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW) data were found for samples of synthetic and "natural" origin. PMID:15969525

Tamura, Hirotoshi; Appel, Markus; Richling, Elke; Schreier, Peter

2005-06-29

312

Ion Mobility Mass Spectrometry for Extracting Spectra of N-Glycans Directly from Incubation Mixtures Following Glycan Release: Application to Glycans from Engineered Glycoforms of Intact, Folded HIV gp120  

NASA Astrophysics Data System (ADS)

The analysis of glycosylation from native biological sources is often frustrated by the low abundances of available material. Here, ion mobility combined with electrospray ionization mass spectrometry have been used to extract the spectra of N-glycans released with PNGase F from a serial titration of recombinantly expressed envelope glycoprotein, gp120, from the human immunodeficiency virus (HIV). Analysis was also performed on gp120 expressed in the ?-mannosidase inhibitor, and in a matched mammalian cell line deficient in GlcNAc transferase I. Without ion mobility separation, ESI spectra frequently contained no observable ions from the glycans whereas ions from other compounds such as detergents and residual buffer salts were abundant. After ion mobility separation on a Waters T-wave ion mobility mass spectrometer, the N-glycans fell into a unique region of the ion mobility/ m/z plot allowing their profiles to be extracted with good signal:noise ratios. This method allowed N-glycan profiles to be extracted from crude incubation mixtures with no clean-up even in the presence of surfactants such as NP40. Furthermore, this technique allowed clear profiles to be obtained from sub-microgram amounts of glycoprotein. Glycan profiles were similar to those generated by MALDI-TOF MS although they were more susceptible to double charging and fragmentation. Structural analysis could be accomplished by MS/MS experiments in either positive or negative ion mode but negative ion mode gave the most informative spectra and provided a reliable approach to the analysis of glycans from small amounts of glycoprotein.

Harvey, David J.; Sobott, Frank; Crispin, Max; Wrobel, Antoni; Bonomelli, Camille; Vasiljevic, Snezana; Scanlan, Christopher N.; Scarff, Charlotte A.; Thalassinos, Konstantinos; Scrivens, James H.

2011-03-01

313

Radiation metabolomics. 3. Biomarker discovery in the urine of gamma-irradiated rats using a simplified metabolomics protocol of gas chromatography-mass spectrometry combined with random forests machine learning algorithm.  

PubMed

Abstract Radiation metabolomics employing mass spectral technologies represents a plausible means of high-throughput minimally invasive radiation biodosimetry. A simplified metabolomics protocol is described that employs ubiquitous gas chromatography-mass spectrometry and open source software including random forests machine learning algorithm to uncover latent biomarkers of 3 Gy gamma radiation in rats. Urine was collected from six male Wistar rats and six sham-irradiated controls for 7 days, 4 prior to irradiation and 3 after irradiation. Water and food consumption, urine volume, body weight, and sodium, potassium, calcium, chloride, phosphate and urea excretion showed major effects from exposure to gamma radiation. The metabolomics protocol uncovered several urinary metabolites that were significantly up-regulated (glyoxylate, threonate, thymine, uracil, p-cresol) and down-regulated (citrate, 2-oxoglutarate, adipate, pimelate, suberate, azelaate) as a result of radiation exposure. Thymine and uracil were shown to derive largely from thymidine and 2'-deoxyuridine, which are known radiation biomarkers in the mouse. The radiation metabolomic phenotype in rats appeared to derive from oxidative stress and effects on kidney function. Gas chromatography-mass spectrometry is a promising platform on which to develop the field of radiation metabolomics further and to assist in the design of instrumentation for use in detecting biological consequences of environmental radiation release. PMID:19630524

Lanz, Christian; Patterson, Andrew D; Slavík, Josef; Krausz, Kristopher W; Ledermann, Monika; Gonzalez, Frank J; Idle, Jeffrey R

2009-08-01

314

gamma ray astronomy with muons  

Microsoft Academic Search

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 ``enhancement'' of muons from gamma ray primaries as compared to that from nucleon primaries. All shower gamma rays above the

Francis Halzen; Todor Stanev; Gaurang B. Yodh

1997-01-01

315

Liquid chromatography/mass spectrometry of domoic acid and lipophilic shellfish toxins with selected reaction monitoring and optional confirmation by library searching of product ion spectra.  

PubMed

LC/MS methodology for the analysis of domoic acid and lipophilic toxins in shellfish was developed using a hybrid triple quadrupole linear ion trap mass spectrometer. For routine quantitation a scheduled selected reaction monitoring (SRM) method for the analysis of domoic acid, okadaic acid, dinophysistoxins, azaspiracids, pectenotoxins, yessotoxins, gymnodimines, spirolides, and pinnatoxins was developed and validated. The method performed well in terms of LOD, linearity, precision, and trueness. Taking advantage of the high instrument sensitivity, matrix effects were mitigated by reducing the amount of sample introduced to the mass spectrometer. Optionally, samples can be analyzed using information dependent acquisition (IDA) methods, either in positive or negative mode, which can provide an extra level of confirmation by matching the full product ion spectra acquired for a sample with those from a specially constructed spectral library. Methods were applied to the analysis df a new certified reference material and Canadian mussels (Mytilus edulis) implicated in a 2011 diarrhetic shellfish poisoning (DSP) incident. The scheduled SRM method enabled the screening and quantitation of multiple phycotoxins. As DSP had not previously been observed in this area of Canada, positive identification of putative toxins was accomplished using the IDA and spectral search method. Analysis of the 2011 toxic mussel samples revealed the presence of high levels of dinophysistoxin-1, which explained the DSP symptoms, as well as pectenotoxins, yessotoxins, and variety of cyclic imines. PMID:24830142

McCarron, Pearse; Wright, Elliott; Quilliam, Michael A

2014-01-01

316

Fusion of time-dependent gamma production spectra from thermal neutron capture and fast neutron inelastic scattering to improve material detection  

Microsoft Academic Search

Neutron-based inspection techniques are unique in their ability to provide material specific signatures, thus offering very high performance and automatic detection of explosives and other contraband. Thermal neutron capture gamma spectroscopy provides excellent sensitivities to hydrogen, nitrogen, chlorine, and other elements, which are characteristic to most explosives, drugs and other contraband that may be smuggled into the country. Fast neutron

T. Gozani; M. Elsalim; D. Strellis; D. Brown

2003-01-01

317

Fusion of time-dependent gamma production spectra from thermal neutron capture and fast neutron inelastic scattering to improve material detection  

NASA Astrophysics Data System (ADS)

Neutron-based inspection techniques are unique in their ability to provide material specific signatures, thus offering very high performance and automatic detection of explosives and other contraband. Thermal neutron capture gamma spectroscopy provides excellent sensitivities to hydrogen, nitrogen, chlorine, and other elements, which are characteristic to most explosives, drugs and other contraband that may be smuggled into the country. Fast neutron gamma production (mostly through inelastic scattering) provides good sensitivity to carbon and oxygen. When necessary, these two types of complementary interactions can be combined to yield a more accurate material determination inside small to medium size containers. Standard pulsed 14 MeV electronic neutron generators offer an efficient way to obtain these two types of interactions. Fast (14 MeV) neutrons are produced during the pulse. After the pulse, only the decaying thermal neutron population exists, and thus pure neutron capture gamma-rays are produced. Unfortunately, during the pulse (which is normally much longer than the neutron thermalization time) the fast neutron interactions are highly "contaminated" by the interactions of thermal neutrons within the object and the nearby gamma-ray detectors. This creates high background and spectral interferences in the common medium resolution detectors, such as NaI, BGO, etc. The use of an appropriate shielding, neutron spectrum tailoring, full spectral feature analysis as well as temporal information ("die-away" time) resulted in significant performance enhancements in detection of explosives, drugs and other contraband in difficult geometries.

Gozani, T.; Elsalim, M.; Strellis, D.; Brown, D.

2003-06-01

318

Toward prompt gamma spectrometry for monitoring boron distributions during extra corporal treatment of liver metastases by boron neutron capture therapy: a Monte Carlo simulation study.  

PubMed

A Monte Carlo calculation was carried out for boron neutron capture therapy (BNCT) of extra corporal liver phantom. The present paper describes the basis for a subsequent clinical application of the prompt gamma spectroscopy set-up aimed at in vivo monitoring of boron distribution. MCNP code was used first to validate the homogeneity in thermal neutron field in the liver phantom and simulate the gamma ray detection system (collimator and detector) in the treatment room. The gamma ray of 478 keV emitted by boron in small specific region can be detected and a mathematical formalism was used for the tomography image reconstruction. PMID:19394243

Khelifi, R; Nievaart, V A; Bode, P; Moss, R L; Krijger, G C

2009-07-01

319

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

320

Gamma Ray Spectrum Catalogs from Idaho National Laboratory (INL)  

DOE Data Explorer

Gamma-ray spectrometry is widely applied as a tool for the assay of radioactive source material to identify the isotopes present and characterize radiation fields. Beginning with the startup of the world's first high-flux beam reactor, Materials Test Reactor (MTR), INL has pioneered the development of x-ray spectrometry for use in basic nuclear research and a variety of disciplines using radioisotopes and other radiation sources. Beginning in the early 1950s, a program was instituted to make the technique a precise laboratory tool. Standards were established for detectors and nuclear electronics to promote the production of commercial laboratory spectrometers. It was also necessary to produce a comprehensive collection of standard detector response functions for individual radio nuclides to permit the use of gamma-ray spectrometers for identification of radioisotopes present in radiation sources. This led to the publication of standard measurement methodology and a set of Gamma-Ray Spectrum Catalogues. These publications, which established standards for detector systems, experimental methods and reference spectra for both NaI (Tl) scintillation detectors and Ge(Li) - Si( Li) semiconductor devices, became standard reference works, distributed worldwide. Over 40,000 copies have been distributed by the Office of Science and Technical Information (OSTI). Unfortunately, although they are still very much in demand, they are all out of print at this time. The INL is converting this large volume of data to a format which is consistent with current information technology and meets the needs of the scientific community. Three are available online with the longest being more than 800 pages in length. Plotted spectra and decay data have been converted to digital formats and updated, including decay scheme graphics. These online catalogs are: • Ge(Li)-Si(Li) Gamma Spectrum Catalog (Published 3-29-1999) • NaI(Tl) Gamma Spectrum Catalog (Published 4-1-1997) • Gamma-ray Spectrum Catalog (opens in a new window)

Heath, R.L.

321

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

322

Selective fast-neutron spectrometry  

Microsoft Academic Search

A procedure for measuring inelastic-scattering spectra of neutrons by coincidences of gamma quanta accompanying deexcitation of excited states of nuclei is described. The time resolution of the spectrometer is a function of the energy of the gamma quanta recorded and varies from 6 nsec for 122 keV to 1.2 nsec for 1.33 MeV. Experimental spectra for the reaction ⁵⁶Fe (n,

E. A. Andreev; V. K. Basenko; S. A. Pshenichnyi; S. P. Sitko; V. A. Stepanko

1985-01-01

323

Development activities of a CdTe/CdZnTe pixel detector for gamma-ray spectrometry with imaging and polarimetry capability in astrophysics  

NASA Astrophysics Data System (ADS)

In the last few years we have been working on feasibility studies of future instruments in the gamma-ray range, from several keV up to a few MeV, in collaboration with other research institutes. High sensitivities are essential to perform detailed studies of cosmic explosions and cosmic accelerators, e.g., Supernovae, Classical Novae, Supernova Remnants (SNRs), Gamma-Ray Bursts (GRBs), Pulsars, Active Galactic Nuclei (AGN).Cadmium Telluride (CdTe) and Cadmium Zinc Telluride (CdZnTe) are very attractive materials for gamma-ray detection, since they have already demonstrated their great performance onboard current space missions, such as IBIS/INTEGRAL and BAT/SWIFT, and future projects like ASIM onboard the ISS. However, the energy coverage of these instruments is limited up to a few hundred keV, and there has not been yet a dedicated instrument for polarimetry.Our research and development activities aim to study a gamma-ray imaging spectrometer in the MeV range based on CdTe detectors, suited either for the focal plane of a focusing mission or as a calorimeter for a Compton camera. In addition, our undergoing detector design is proposed as the baseline for the payload of a balloon-borne experiment dedicated to hard X- and soft gamma-ray polarimetry, currently under study and called C?SP (CZT ?-Spectrometer Polarimeter). Other research institutes such as INAF-IASF, DTU Space, LIP, INEM/CNR, CEA, are involved in this proposal. We will report on the main features of the prototype we are developing at the Institute of Space Sciences, a gamma-ray detector with imaging and polarimetry capabilities in order to fulfil the combined requirement of high detection efficiency with good spatial and energy resolution driven by the science.

Gálvez, J. L.; Hernanz, M.; Álvarez, J. M.; Álvarez, L.; La Torre, M.; Caroli, E.; Lozano, M.; Pellegrini, G.; Ullán, M.; Cabruja, E.; Martínez, R.; Chmeissani, M.; Puigdengoles, C.

2013-05-01

324

Comparison of the gamma-ray spectra from 2. 8keV neutron capture and thermal-neutron capture in sodium-23  

Microsoft Academic Search

The gamma-ray spectrum resulting from neutron capture in the 2.8-keV resonance of ²³Na has been measured with the high-resolution annihilation pair spectrometer at the internal-target facility of the CP-5 reactor. The 2.8-keV resonance was populated by using the boron-shielded target technique: A ¹\\/â-in.-thick filter of ¹°B surrounding the sodium sample selectively removes low-energy neutrons from the spectrum; the 1\\/E dependence

W. M. Wilson; H. E. Jackson; G. E. Thomas

1977-01-01

325

Spectra and angular distributions of atmospheric gamma rays from 0.3 to 10 MeV at lambda = 40 deg  

NASA Technical Reports Server (NTRS)

Measurements of the spectral and angular distributions of atmospheric gamma sq cm rays in the energy range 0.3-10 MeV over Palestine, Texas, at residual depths of 2.5 and 70 g/sq cm are reported. In confirmation of the general features of a model prediction, the measurements show at 2.5 g/sq cm upward moving fluxes greater than the downward moving fluxes, the effect increasing with energy, and approximate isotropy at 70 g/sq cm. Numerous characteristic gamma-ray lines were observed, most prominently at 0.511, 1.6, 2.3, 4.4, and 6.1 MeV. Their intensities were also compared with model predictions. Observations were made with an actively shielded scintillator counter with two detectors, one of aperture 50 deg FWHM and the other of 120 deg FWHM. Above 1 MeV, contributions to the counting rate from photons penetrating the shield annulus and from neutron interactions were large; they were studied by means of a Monte Carlo code and are extensively discussed.

Ling, J. C.; Gruber, D. E.

1977-01-01

326

Which unidentified EGRET sources are gamma-ray pulsars?  

Microsoft Academic Search

We consider high energy gamma -ray radiation from the radio pulsars associated with some unidentified EGRET gamma -ray sources. Calculated efficiencies for the conversion of spin-down power to gamma -rays and the energy spectra of the high energy gamma -rays from these possible gamma -ray pulsars in outer gap models are compared with observed results. Of these possible gamma -ray

L. Zhang; K. S. Cheng

1998-01-01

327

Improved radioxenon gamma-spectrometry counting system and its efficiency calibration: Monte Carlo simulation and experimental results at enriched xenon counting environment  

Microsoft Academic Search

To give satisfactory efficiency both for X- and gamma-ray photon, an improved counting system has been developed in CTBT Canadian\\u000a radioxenon laboratory. The counting system consists of a BEGe detector coupled with a thin carbon fiber window counting cell,\\u000a that can perform a reliable and efficient radioxenon measurement. A semi-empirical calibration procedure was adopted, which\\u000a is a combination of experimental

W. Zhang; K. Ungar; M. Bean

2009-01-01

328

Use of the 1001 keV peak of 234mPa daughter of 238U in measurement of uranium concentration by HPGe gamma-ray spectrometry  

Microsoft Academic Search

For the direct gamma-ray spectrometric measurements of uranium concentrations in the samples, the use of 1001keV peak of 234mPa, second daughter of 238U is emphasized. This “clean” peak is well resolved by HPGe detectors and gives accurate indication of uranium concentration in the samples without any self-absorption correction. The 1001keV peak of 234mPa in the 238U chain is selected because

H Yücel; M. A Çetiner; H Demirel

1998-01-01

329

Selective fast-neutron spectrometry  

SciTech Connect

A procedure for measuring inelastic-scattering spectra of neutrons by coincidences of gamma quanta accompanying deexcitation of excited states of nuclei is described. The time resolution of the spectrometer is a function of the energy of the gamma quanta recorded and varies from 6 nsec for 122 keV to 1.2 nsec for 1.33 MeV. Experimental spectra for the reaction /sup 56/Fe (n, n' gamma) are presented. The gamma detector simultaneously selects events related to the excitation of a given nuclear state and provides a point of reference for the time-of-flight neutron spectrometer. The presence in the experimental spectra of several groups of neutrons allows determination of the direct as well as cascade population of the level in question.

Andreev, E.A.; Basenko, V.K.; Pshenichnyi, S.A.; Sit'ko, S.P.; Stepanko, V.A.

1985-11-01

330

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

331

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

332

Comparison of inductively coupled mass spectrometry and ultra low-level gamma-ray spectroscopy for ultra low background material selection.  

PubMed

The main target of this study is the development and the validation of an internal procedure to measure the pg g(-1) levels, of naturally occurring radioisotopes to select ultra low background detector materials. As there are no ultra low-level certified reference materials commercially available, the performance of ICP-MS was compared with the well established ultra low-level gamma-spectroscopy. This work shows also the reliability of very quick ICP-MS semi-quantitative analyses of an environmental matrix such as a geological sample treated according to conventional protocols. PMID:19269836

Nisi, S; Di Vacri, A; Di Vacri, M L; Stramenga, A; Laubenstein, M

2009-05-01

333

Gamma scattering  

SciTech Connect

Experimental examinations have been performed on a gamma scattering source/detector configuration that is believed to have the potential for providing density information at a finite number of positions along the primary beam and the average attenuation along the exit rays from those positions. Scattering spectra were acquired for several void-fluid density distribution simulations. The multiple-scattered photon contribution to the total acquired spectrum from a water-filled pipe simulation was extracted and found to be between 18 to 33% of the total counts in the single-scattered photon energy region, with a region average of 24%.

Baker, A.G.

1980-01-01

334

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

335

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

336

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

337

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  

NASA Astrophysics Data System (ADS)

(+)-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 the inhibitor property. A systematic quantum chemical study of the possible conformations, their relative stabilities, FT-Raman, FT-IR and UV-vis spectroscopic analysis of bicuculline has been reported. The optimized geometries, wavenumber and intensity of the vibrational bands of all the conformers of bicuculline have been calculated using ab initio Hartree-Fock (HF) and density functional theory (DFT) employing B3LYP functional and 6-311G(d,p) basis set. Mulliken atomic charges, HOMO-LUMO gap ? E, ionization potential, dipole moments and total energy have also been obtained for the optimized geometries of both the molecules. TD-DFT method is used to calculate the electronic absorption parameters in gas phase as well as in solvent environment using integral equation formalism-polarizable continuum model (IEF-PCM) employing 6-31G basis set and the results thus obtained are compared with the UV absorption spectra. The combination of experimental and calculated results provides an insight into the structural and vibrational spectroscopic properties of bicuculline.

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

2011-12-01

338

Determination of gamma-hydroxybutyric acid in biofluids using a one-step procedure with "in-vial" derivatization and headspace-trap gas chromatography-mass spectrometry.  

PubMed

A headspace-trap gas chromatography-mass spectrometry (HS-trap GC-MS) method was developed to determine GHB, a low molecular weight compound and drug of abuse, in various biological fluids. Combining this relatively novel and fully automated headspace technique with "in-vial" methylation of GHB allowed for a straightforward approach. One single method could be used for all biofluids (urine, plasma, serum, whole blood or lyzed blood), requiring only 100?l of sample. Moreover, our approach involves mere addition of all reagents and sample into one vial. Following optimization of headspace conditions and trap settings, validation was performed. Although sample preparation only consists of the addition of salt and derivatization reagents directly to a 100?l-sample in a HS-vial, adequate method sensitivity and selectivity was obtained. Calibration curves ranged from 5 to 150?g/ml GHB for urine, from 2 to 150?g/ml for plasma, and from 3.5 to 200?g/ml for whole blood. Acceptable precision and accuracy (<13% bias and imprecision) were seen for all quality controls (QC's) (LLOQ-level, low, medium, high), including for the supplementary serum- and lyzed blood-based QC's, using calibration curves prepared in plasma or whole blood, respectively. Incurred sample reanalysis demonstrated assay reproducibility, while cross-validation with another GC-MS method demonstrated that our method is a valuable alternative for GHB determination in toxicological samples, with the advantage of requiring only 100?l and minimal hands-on time, as sample preparation is easy and injection automated. PMID:23664352

Ingels, Ann-Sofie M E; Neels, Hugo; Lambert, Willy E; Stove, Christophe P

2013-06-28

339

EPR Spectra of Some Irradiated Polycrystalline Perrhenates.  

National Technical Information Service (NTIS)

An EPR study of the paramagnetic centers formed by gamma , electron and neutron irradiation of the NaReO sub 4 and KReO sub 4 was made. In the EPR spectra of the powder samples irradiated gamma , with electrons and neutrons, the presence of three types of...

N. G. Zaitseva M. Constantinescu R. Georgescu O. Constantinescu

1978-01-01

340

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

341

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

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 (238)U, (232)Th, and (40)K 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 (238)U, (232)Th, and (40)K 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

2010-10-01

342

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.

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

2010-01-01

343

Gamma-Ray Detectors  

NASA Astrophysics Data System (ADS)

The common methods of analyzing gamma-ray spectra obtained from detectors capable of energy discrimination are discussed. Gamma-ray spectra generally are in the form of detector response versus discrete channel number. The methods considered for gamma-ray spectroscopy are somewhat general and can be applied to other types of spectroscopy. The general objective of spectroscopy is to obtain, at a minimum, the qualitative identification of the source (e.g., source energies or nuclides present). However, most spectroscopy applications seek quantitative information also, as expressed by, e.g., the source strength or the nuclide concentration. Various different methods for qualitative and quantitative analysis are summarized, and an illustrative example is provided. A review of detectors used for gamma-ray spectroscopy is included.

Dunn, William L.; McGregor, Douglas S.

344

Gamma ray pulsars: Observations  

Microsoft Academic Search

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

David J. Thompson

2001-01-01

345

A preliminary report on the determination of natural radioactivity levels of the State of Qatar using high-resolution gamma-ray spectrometry  

NASA Astrophysics Data System (ADS)

This study is aimed at the determination of the activity concentrations of naturally occuring and technically enhanced levels of radiation in soil samples collected across the landscape of Qatar. Representative soil samples from various locations across the Qatarian peninsula have been collected and analyzed in order to establish activity concentrations associated with the 235,8U and 232Th natural decay chains and also the long-lived naturally occurring radionuclide 40K. The activity concentrations have been measured using a hyper-pure germanium detector. Details of the sample preparation and the gamma-ray spectroscopic analysis techniques are presented, together with the preliminary values of the activity concentrations associated with the naturally occuring radionuclide chains for six soil samples collected from the Qatarian peninsula. Sample 228, which has been collected from an inshore oil-field area, was observed to have the highest observed value of 226Ra concentration among the six samples. The weighted mean values of the activity concentrations of the radionuclides 238U, 232Th and 40K in one particular sample (sample 228) were, respectively, found to be 213.9±1.4, 4.55±0.11 and 111.4±3.6 Bq/kg, which compare with the worldwide weighted mean values in soil samples, 33, 45 and 420 Bq/kg, respectively. The deduced activity concentration of 238U in sample 228 in the current work was found to be significantly higher than the worldwide average value and was also significantly higher than the values determined for the five other initial samples discussed here. The mean values of the activity concentration of the 232Th series, 40K and 137Cs in Bq/kg from the six investigated soil samples were found to be 9.4±1.3, 204±22 and 5.8±5.6, respectively, with the quoted uncertainty referring to the standard deviation among these measurements.

Al-Sulaiti, H.; Regan, P. H.; Bradley, D. A.; Malain, D.; Santawamaitre, T.; Habib, A.; Matthews, M.; Bukhari, S.; Al-Dosari, M.

2010-07-01

346

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

347

Isolation of Montecristin, a Key Metabolite in Biogenesis of Acetogenins from Annona muricata and Its Structure Elucidation by Using Tandem Mass Spectrometry.  

PubMed

During the course of our continuing search for acetogenins from Annonaceae, a new metabolite, montecristin, possibly involved in the biogenesis of acetogenins, was isolated from the roots of Annona muricata. Its structure was elucidated on the basis of UV, IR, (1)H and (13)C NMR, and mass spectrometry. The identification of the main stuctural features of montecristin (1) was obtained from the NMR spectra whereas their locations on the alkyl chain were evidenced by using mass spectrometry. The attribution of each carbon and location of substituents on the alkyl chain of this fatty acid gamma-lactone was evidenced by using tandem mass spectrometry (MS/MS) and high-energy collisional activation of [M + Li](+) lithium complexes. Finally, the structure determination of montecristin was strengthened by epoxidation and transformation leading to a known adjacent bis-tetrahydrofuran acetogenin. PMID:11671442

Gleye, C.; Laurens, A.; Hocquemiller, R.; Cavé, A.; Laprévote, O.; Serani, L.

1997-02-01

348

K-Th-Ti systematics and new three-component mixing model of HED meteorites: Prospective study for interpretation of gamma-ray and neutron spectra for the Dawn mission  

NASA Astrophysics Data System (ADS)

The Dawn spacecraft carries a gamma-ray and neutron detector (GRaND), which will measure and map the abundances of selected elements on the surface of asteroid 4 Vesta. We compare the variability of moderately volatile/refractory incompatible element ratios (K/Th and K/Ti) in howardite, eucrite, and diogenite (HED) meteorites with those in other achondrite suites that represent asteroidal crusts, because these ratios may be accurately measured by GRaND and likely reflect initial chemical compositions of the HED parent body. The K/Th and K/Ti variations can differentiate HED meteorites from angrites and some unique eucrite-like lithologies. The results suggest that K, Th, and Ti abundances determined from GRaND data could not only confirm that Vesta is the parent body of HED meteorites but might also allow recognition of as-yet unsampled compositional terranes on Vesta. Besides the K-Th-Ti systematics study, we propose a new three-component mixing model for interpretation of GRaND spectra, required because the spatial resolution of GRaND is coarser than the spectral (compositional) heterogeneity of Vesta's surface. The mixing model uses abundances of K, Ti, Fe, and Mg that will be analyzed more accurately than other prospective GRaND-analyzed elements. We examine propagated errors due to GRaND analytical uncertainties and intrinsic errors that stem from an assumption introduced into the mixing model. The error investigation suggests that the mixing model can adequately estimate not only the diogenite/eucrite mixing ratio but also the abundances of most major and minor elements within the GRaND propagated errors.

Usui, Tomohiro; McSween, Harry Y. _jr., Jr.; Mittlefehldt, David W.; Prettyman, Thomas H.

2010-07-01

349

Gamma spectroscopy of environmental samples  

NASA Astrophysics Data System (ADS)

We describe experiments for the undergraduate laboratory that use a high-resolution gamma detector to measure radiation in environmental samples. The experiments are designed to instruct the students in the quantitative analysis of gamma spectra and secular equilibrium. Experiments include the radioactive dating of Brazil nuts, determining radioisotope concentrations in natural samples, and measurement of the 235U abundance in uranium rich rocks.

Siegel, P. B.

2013-05-01

350

Fluorescence Spectra  

NSDL National Science Digital Library

This experiment uses the Tracker video analysis and modeling tool to explore the phenomenon of fluorescence and its application in fluorescent lamps. For each of five different visible spectra, students (a) observe the spectrum directly, (b) measure its brightness versus wavelength in Tracker, and (c) answer both qualitative and quantitative questions about it. The spectra include a fluorescent dye with laser and UV illumination, a mercury lamp and two fluorescent lamps, all with red and green laser spots added for easy calibration. For more information, see the AAPT presentation. The zip file includes the lab instructions, spectrum images and Tracker data files. This requires Tracker version 4.62 or higher. Tracker installers are available for Windows, Mac and Linux from ComPADRE or the Tracker web site (http://www.cabrillo.edu/~dbrown/tracker/).

Brown, Douglas

2012-01-17

351

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

352

Gamma-ray spectrometer experiment  

NASA Technical Reports Server (NTRS)

The experiments in gamma-ray spectrometry to determine the geochemical composition of the lunar surface are reported. The theory is discussed of discrete energy lines of natural radioactivity, and the lines resulting from the bombardment of the lunar surface by high energy cosmic rays. The gamma-ray spectrometer used in lunar orbit and during transearth coast is described, and a preliminary analysis of the results is presented.

Arnold, J. R.; Peterson, L. E.; Metzger, A. E.; Trombka, J. I.

1972-01-01

353

Gamma ray spectroscopy in astrophysics. [conferences  

NASA Technical Reports Server (NTRS)

Experimental and theoretical aspects of gamma ray spectroscopy in high energy astrophysics are discussed. Line spectra from solar, stellar, planetary, and cosmic gamma rays are examined as well as HEAO investigations, the prospects of a gamma ray observatory, and follow-on X-ray experiments in space.

Cline, T. L. (editor); Ramaty, R. (editor)

1978-01-01

354

Compton Gamma Ray Observatory Guest Investigator Program  

NASA Technical Reports Server (NTRS)

This paper presents a final report for the Compton Gamma Ray Observatory Guest Investigator Program from 06/01/91-07/31/97. The topics include: 1) Solar Flare Neutron Spectra and Accelerated Ions; 2) Gamma Ray Lines From The Orion Complex; 3) Implications of Nuclear Line Emission From The Orion Complex; 4) Possible Sites of Nuclear Line Emission From Massive OB Associations; 5) Gamma-Ray Burst Repitition and BATSE Position Uncertainties; 6) Effects of Compton Scattering on BATSE Gamma-Ray Burst Spectra; and 7) Selection Biases on the Spectral and Temporal Distribution of Gamma Ray Bursts.

Lingenfelter, Richard E.

1997-01-01

355

Reduction of multielement mass spectra  

SciTech Connect

Even though the spectra obtained by inductively coupled plasma source spectrometry (ICP-MS) are relatively simple, their interpretation can be complicated by the presence of molecular and isobaric interferants. To the extent that isotopic abundances are known and constant, one can treat observed spectra as sums of known components. A linear decomposition approach for determining the concentrations of the components in a spectrum and correctly propagating uncertainties is presented. This technique differs from linear regression in that an exact fit is made to a subset of isotopes and goodness-of-fit is evaluated from the deviations between the predicted and measured intensities of the other, unfit isotopes. This technique can be applied to a wide range of spectral fitting problems. In this paper, its applicability to ICP-MS spectra is used to demonstrate the use and utility of the technique. 2 refs., 9 figs.

Russ, G.P. III; Caffee, M.W.; Hudson, G.B.; Storch, N.A.

1990-06-29

356

Dosage a tres bas niveau de radionucleides a longue periode emetteurs (beta) ou (alpha) par spectrometrie de masse a couplage plasma inductif. (Measurements of (beta) or (alpha) emitter long lived radionuclides using inductively coupled plasma mass spectrometry).  

National Technical Information Service (NTIS)

The measurement of long-lived radionuclides is highly important for characterizing nuclear wastes for their later storage. The main techniques are (alpha) spectrometry, (beta) counting and (gamma) spectrometry. The large period of these isotopes leads to ...

O. Provitina

1993-01-01

357

Neutron Capture gamma-Ray Facility.  

National Technical Information Service (NTIS)

A neutron capture gamma-ray facility was constructed for prompt gamma-ray spectrometry, and its characteristics were measured. In the facility, a neutron beam is extracted from the H-6 horizontal experimental hole of Japan Research Reactor No.3, JAERI, an...

T. Tojo C. Yonezawa S. Koura S. Arai T. Komori

1980-01-01

358

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

359

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

360

Infrared spectra of olivine polymorphs - Alpha, beta phase and spinel  

NASA Technical Reports Server (NTRS)

The infrared absorption spectra of several olivines (alpha phase) and their corresponding beta phase (modified spinel) and spinel (gamma) high-pressure polymorphs are determined. Spectra were measured for ground and pressed samples of alpha and gamma A2SiO4, where A = Fe, Ni, Co; alpha and gamma Mg2GeO4; alpha Mg2SiO4; and beta Co2SiO4. The spectra are interpreted in terms of internal, tetrahedral and octagonal, and lattice vibration modes, and the spinel results are used to predict the spectrum of gamma Mg2SiO4. Analysis of spectra obtained from samples of gamma Mg2GeO4 heated to 730 and 1000 C provides evidence that partial inversion could occur in silicate spinels at elevated temperatures and pressures.

Jeanloz, R.

1980-01-01

361

Spectral archives: extending spectral libraries to analyze both identified and unidentified spectra  

Microsoft Academic Search

Tandem mass spectrometry (MS\\/MS) experiments yield multiple, nearly identical spectra of the same peptide in various laboratories, but proteomics researchers typically do not leverage the unidentified spectra produced in other labs to decode spectra they generate. We propose a spectral archives approach that clusters MS\\/MS datasets, representing similar spectra by a single consensus spectrum. Spectral archives extend spectral libraries by

Ari M. Frank; Matthew E. Monroe; Anuj R. Shah; Jeremy J. Carver; Nuno Bandeira; Ronald J. Moore; Gordon A. Anderson; Richard D. Smith; Pavel A. Pevzner

2011-01-01

362

Denoising analysis of Hadamard transform spectrometry.  

PubMed

We discuss denoising in Hadamard transform spectrometry (HTS) in terms of sensor noise, photon noise, and the sparsity of the source. An analysis based on spectra classification is proposed to estimate the signal-to-noise ratio (SNR) of both HTS and slit-based spectrometry. In contrast with previous theory, it is shown that HTS can improve the sensitivity of the sensor and that HTS outperforms slit-based spectrometry when the signal is dominated by photon noise and the source is sparse. Numerical simulations show that HTS is a good method for improving the poor SNR associated with weak or sparse signals. PMID:24978726

Yue, Jiang; Han, Jing; Zhang, Yi; Bai, Lian-Fa

2014-07-01

363

Pulsed Positive Negative Ion Chemical Ionization Mass Spectrometry.  

National Technical Information Service (NTIS)

Simultaneous recording of positive and negative chemical ionization (CI) mass spectra is described. The capability of this technique, and negative ion CI mass spectrometry in general, to provide a hundred- to a thousand-fold increase in sample ion current...

D. F. Hunt G. C. Stafford F. W. Crow J. W. Russell

1976-01-01

364

Analysis of expressed sequence tags from a single wheat cultivar facilitates interpretation of tandem mass spectrometry data and discrimination of gamma gliadin proteins that may play different functional roles in flour  

Microsoft Academic Search

BACKGROUND: The gamma gliadins are a complex group of proteins that together with other gluten proteins determine the functional properties of wheat flour. The proteins have unusually high levels of glutamine and proline and contain large regions of repetitive sequences. While most gamma gliadins are monomeric proteins containing eight conserved cysteine residues, some contain an additional cysteine residue that enables

Susan B. Altenbach; Wiliiam H. Vensel; Frances M. DuPont

2010-01-01

365

Some diatomic molecules from comet P/Halley's UV spectra near spacecraft flybys  

NASA Technical Reports Server (NTRS)

The abundances of diatomic molecules seen in the UV both give clues to the parent compounds and help unravel the gas and ion mass spectrometry. From IUE spectra of comet Halley, upper limits on SH and CS(+) column densities and estimates of probable NO, S2, and SO are found. In particular, judged from the 226-nm gamma band, NO was relatively abundant at 2-8 x 10 to the 13th/sq cm on March 9-14. The production rate of S2 was around 1 x 10 to the 27th molecules/s at that time, but both showed day-to-day variability by 2-3 times.

Wallis, Max K.; Krishna Swamy, K. S.

1987-01-01

366

Method for the analysis of echelle spectra  

US Patent & Trademark Office Database

A method for the wavelength calibration of echelle spectra, in which the wavelengths are distributed across number of orders is characterised by the steps: recording of a line-rich reference spectrum with known wavelengths for a number of the lines, determination of the position of a number of peaks of the reference spectrum in the recorded spectrum, selection of at least two first lines of known order, position and wavelength, determination of a wavelength scale for the order in which the known lines lie, by means of a fit function .gamma..sub.m(x), determination of a provisional wavelength scale .gamma.?m 1(x) for at least one neighboring order m 1, by means of addition/subtraction of a wavelength difference .gamma..sub.FSR which corresponds to a free spectral region, according to .gamma.m 1 ?(x)=.gamma..sub.m(x).gamma..sub.FSR with .gamma..sub.FSR=.gamma..sub.m(x)/m, determination of the wavelengths of lines in said neighboring order m 1, by means of the provisional wavelength scale .gamma. 1(x), replacement of the provisional wavelength of at least two lines by the reference wavelength for said lines as obtained in step (a) and repeat of steps (d) to (g) for at least one further neighboring order.

2008-01-15

367

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

368

Electrospray mass spectra of lanthanides  

SciTech Connect

The electrospray mass spectra of several elements in the lanthanide series are presented with the focus being on understanding the basic processes that occur to yield such spectra. The solution chemistry and the physical properties of the elements have a profound effect on the type of species observed in a mass spectrum. To perform elemental analysis by electrospray mass spectrometry, harsh declustering conditions are typically used. This results in a spectrum consisting of the bare metal ion (Ln[sup +] or Ln[sup 2+]) and molecular ions (LnO[sup +]) such as oxides as well as contributions due to matrix ions. The sampling conditions required to obtain such spectra require a large potential difference between the sampling plate and the skimmer at the atmosphere to vacuum interface, resulting in efficient collision-induced dissociation conditions. To monitor the process, a frame by frame illustration is used where the potential difference between the sampling plate and skimmer is increased in increments and the resultant spectra are captured. With this procedure, the dominant processes may be highlighted and explained step by step and a clearer understanding of the processes involved is obtained. 43 refs., 7 refs., 1 tab.

Stewart, I.I.; Horlick, G. (Univ. of Alberta, Edmonton, Alberta (Canada))

1994-11-15

369

{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

370

Mass spectrometry with direct supercritical fluid injection  

Microsoft Academic Search

Direct fluid injection mass spectrometry utilizes supercritical fluids for solvation and transfer of materials to a mass spectrometer chemical ionization (CI) source. Available data suggest that any material soluble in a supercritical fluid is transferred efficiently to the ionization region. Mass spectra are presented for mycotoxins of the trichothecene group obtained by use of supercritical carbon dioxide with isobutane as

Richard D. Smith; Harold R. Udseth

1983-01-01

371

Raman spectrometry  

SciTech Connect

The period of this review includes material published from late 1979 to late 1981. Ca 3700 papers have appeared dealing with Raman spectrometry. The author has tried to be highly selective in collecting material which has clear relevance to analytical chemistry. Where possible, reviews, in specific areas to which the reader is referred for a complete background, have been included. A statistical analysis of the development and applications of Raman Spectroscopy from 1928 to 1978, has been published and includes a glossary of different types of Raman excitation. Some general and industrial applications have been briefly reviewed and the possibility of using the Raman effect to probe the composition of planetary atmospheres has been discusses. Several references of the application of Raman spectroscopy to solids are included. 286 references.

Gardiner, D.J.

1982-04-01

372

NEGATIVE-ION MASS SPECTROMETRY OF SULFONYLUREA HERBICIDES  

EPA Science Inventory

Sulfonylurea herbicides have been studied using neg-ion desorption chem.-ionization (DCI) mass spectrometry (MS) and DCI-MS/MS techniques. Both {M-H]- and M.- ions were obsd. in the DCI mass spectra. The collisonally activated dissocn. (CAD) spectra were characteristic of the str...

373

Optimization of multielement gamma activation analysis  

Microsoft Academic Search

The authors present a technique for optimizing the gamma activation analysis of trap rock using the OPTIMUM program. Comparative results are presented for the calculated and measured radioactivity, in optimal regimes of the gamma spectra, induced by the bremmstrahlung from electron accelerators in standard samples of igneous trap rock. The optimization criterion employs the functions associated with the error in

M. G. Davydov; V. V. Kishel'gof; B. A. Chapyzhnikov; V. A. Shcherbachenko

1987-01-01

374

SIMULATE Program: a gamma ray spectroscopy tool  

Microsoft Academic Search

A software package which simulates the virtual creation of gamma ray spectra emitted from a combination of radioactive sources, as seen by a semiconductor or scintillation detector, is presented . It partially utilizes Monte Carlo techniques based on the physics of gamma ray spectroscopy. In addition, certain algorithms are used to compensate for the premature termination of the fate of

C. A Kalfas; E. Tsoulou

2003-01-01

375

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

376

Analysis of Pulse Height Spectra from an Organic Scintillator Spectrometer.  

National Technical Information Service (NTIS)

A suite of three computer codes has been written to analyse the pulse height spectra from an organic scintillator neutron or gamma ray spectrometer. Data prepared by the first code are submitted to the second which unfolds the pulse height spectra. Compar...

S. Whittlestone

1980-01-01

377

Diffuse galactic gamma ray lines  

NASA Technical Reports Server (NTRS)

The production rate of 4.44-MeV line for a variety of assumed cosmic ray spectra is evaluated. These results are compared with reported galactic gamma-ray line intensities and are consistent with a low energy cosmic ray density which increases toward the galactic center in proportion to the molecular gas density.

Lingenfelter, R. E.; Ramaty, R.

1977-01-01

378

RICKI. Interactive Gamma Spectral Analysis  

Microsoft Academic Search

RICKI is an interactive program for analysis of gamma spectra containing one or more peaks with possible multiplets. Algorithms are incorporated for peak fitting, analysis, and nuclide identification. Comprehensive output keeps the user informed of the analysis as it proceeds and presents the results. User-selectable options for plotting and neutron activation analysis are available to control this analysis. RICKI was

Proctor

1988-01-01

379

Simulated spectra for QA\\/QC of spectral analysis software  

Microsoft Academic Search

Monte Carlo simulated spectra have been developed to test the peak analysis algorithms of several spectral analysis software packages. Using MCNP 5, generic sample spectra were generated in order to perform ANSI N42.14 standard spectral tests on Canberra Genie-2000, Ortec GammaVision, and UniSampo. The reference spectra were generated in MCNP 5 using an F8, pulse height, tally with a detector

K. R. Jackman; S. R. Biegalski

2004-01-01

380

Electrospray ionization and tandem mass spectrometry of cysteinyl eicosanoids: leukotriene C4 and FOG7.  

PubMed

The cysteinyl leukotrienes, LTC4, LTD4 and LTE4, and the recently described cysteinyl eicosanoid, 5-oxo-7-glutathionyl-8,11,14-eicosatrienoic acid (FOG7) have been analyzed by tandem mass spectrometry. Both [M-H]- and [M+H]+ ions were produced by electrospray ionization and collision-induced dissociation of these molecular ion species were studied using both an ion trap and a triple quadrupole instrument. Product ion spectra obtained were characteristic of the structure of the cysteinyl leukotrienes and mechanisms of ion formation were investigated by using deuterium-labeled analogs. The product ion spectrum obtained following collision-induced dissociation of the [M-H]- anion from FOG7 was devoid of significant structural information and further studies of collision activation of the [M+H]+ spectrum were therefore examined. Positive ion MS3 spectra obtained in the ion trap from the gamma-glutamate cleavage products of FOG7 and its derivative (d7-FOG7) afforded an abundant ion not observed in spectra generated from the cysteinyl leukotrienes. Formation of this fragment ion likely occurred via a McLafferty-type rearrangement to afford cleavage of the C6-C7 bond adjacent to the sulfur atom and was valuable for the identification of the structure of FOG7 and defining the biosynthetic pathway as a 1,4-Michael addition of glutathione to 5-oxo-eicosatetraenoic acid (5-oxo-ETE). PMID:11444597

Hevko, J M; Murphy, R C

2001-07-01

381

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

382

Analysis of fissionable material using delayed gamma rays from photofission  

Microsoft Academic Search

The energetic gamma-ray spectra from the fission products of photofission have been investigated to determine whether photofission can identify heavily shielded fissionable material. Target samples of natural thorium, 93% enriched ²³⁵U, natural uranium, and 93% enriched ²³⁹Pu were irradiated with bremsstrahlung gamma rays produced by 10-MeV electrons from a small linear accelerator. The gamma-ray spectra for each of the four

C. L. Hollas; D. A. Close; C. E. Moss

1986-01-01

383

Analysis of fissionable material using delayed gamma rays from photofission  

Microsoft Academic Search

The energetic gamma-ray spectra from the fission products of photofission have been investigated to determine whether photofission can identify heavily shielded fissionable material. Target samples of natural thorium, 93% enriched 235U, natural uranium, and 93% enriched 239Pu were irradiated with bremsstrahlung gamma rays produced by 10-MeV electrons from a small linear accelerator. The gamma-ray spectra for each of the four

C. L. Hollas; D. A. Close; C. E. Moss

1987-01-01

384

NEAR Gamma Ray Spectrometer Characterization and Repair  

NASA Technical Reports Server (NTRS)

This report covers the work completed in the third year of the contract. The principle activities during this period were (1) the characterization of the NEAR 2 Gamma Ray Spectrometer using a neutron generator to generate complex gamma ray spectra and a large Ge Detecter to identify all the major peaks in the spectra; (2) the evaluation and repair of the Engineering Model Unit of the Gamma Ray Spectrometer for the NEAR mission; (3) the investigation of polycapillary x-ray optics for x-ray detection; and (4) technology transfer from NASA to forensic science.

Groves, Joel Lee; Vajda, Stefan

1998-01-01

385

Status of the GAMMA-400 Project  

NASA Technical Reports Server (NTRS)

The preliminary design of the new space gamma-ray telescope GAMMA-400 for the energy range 100 MeV-3 TeV is presented. The angular resolution of the instrument, 1-2 deg at E(gamma) approximately 100 MeV and approximately 0.01 at E(gamma) greater than 100 GeV, its energy resolution is approximately 1% at E(gamma) greater than 100 GeV, and the proton rejection factor is approximately 10(exp 6) are optimized to address a broad range of science topics, such as search for signatures of dark matter, studies of Galactic and extragalactic gamma-ray sources, Galactic and extragalactic diffuse emission, gamma-ray bursts, as well as high-precision measurements of spectra of cosmic-ray electrons, positrons, and nuclei.

Galper, A. M.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Boezio, M.; Bonvicini, V.; Boyarchuk, K. A.; Gusakov, Yu. V.; Farber, M. O.; Fradkin, M. I.; Kachanov, V. A.; Kaplin, V. A.; Kheymits, M. D.; Leoniv, A. A.; Longo, F.; Maestro, P.; Marrocchesi, P.; Mazets, E. P.; Mocchiutti, E.; Moiseev, A. A.; Mori, N.; Moskalenko, I.; Naumov, P. Yu.; Papini, P.

2013-01-01

386

Gamma Rays  

MedlinePLUS

... infrared, and ultraviolet light, are part of the electromagnetic spectrum. While gamma rays and x-rays pose the same kind of hazard, they differ in their origin. Gamma rays originate in the nucleus. X-rays originate in the electron fields surrounding the nucleus or are machine-produced. What ...

387

Gamma-ray bursters  

NASA Technical Reports Server (NTRS)

Current theoretical models developed to explain the observational data (from spaceborne detectors) on gamma-ray bursters are summarized and illustrated with drawings, diagrams, graphs, and photographic images. Although the data are fragmentary and often flawed by instrument defects, models involving neutron stars with strong magnetic fields are generally favored, and it is assumed that most observed bursters lie within the Galaxy. The neutron-star origin of the bursts is suggested by their intensity and rapid variability (implying a very compact high-energy source) and the presence in some burster spectra of a line at 420 keV which is explained by the combination of electron-positron annihilation and gravitational reddening. Consideration is also given to optical flashes observed to occur about once per year in the direction of gamma bursters, and the need for further searches for lower-energy emissions from bursters is stressed.

Schaefer, B. E.

1985-01-01

388

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 1-10 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 possible launch in 2005, will provide a major advance in sensitivity, energy range, and sky coverage.

Thompson, David J.

2000-01-01

389

Photon spectra from quark generation by WIMPs  

SciTech Connect

If the present dark matter (DM) in the Universe annihilates into Standard Model (SM) particles, it must contribute to the gamma ray fluxes that are detected on the Earth. The magnitude of such contribution depends on the particular DM candidate, but certain features of these spectra may be analyzed in a model-independent fashion. In this work we provide the fitting formula valid for the simulated photon spectra from WIMP annihilation into light quark-anti quark (qq-bar) channels in a wide range of WIMP masses. We illustrate our results for the cc-bar channel.

Cembranos, J. A. R.; Cruz-Dombriz, A.; Maroto, A. L. [Departamento de Fisica Teorica I, Universidad Complutense de Madrid, E-28040 Madrid (Spain) and Department of Mathematics and Applied Mathematics, University of Cape Town, 7700 (South Africa); Dobado, A.; Lineros, R. [IFIC, CSIC-Universitat de Valencia, Ed. Instituts, Apt. 22085, 46071 Valencia (Spain)

2011-05-23

390

Alpha particle induced gamma yields in uranium hexafluoride  

NASA Astrophysics Data System (ADS)

Fluorine has a relatively large (?,n) production cross-section in the MeV range, the energy range of interest for special nuclear materials. In the uranium fuel cycle enriched UF6 in particular is a reasonably prolific source of (?,n) neutrons because along with 235U, 234U becomes enriched and it has a relatively short half-life. This enables the mass content of storage cylinders containing UF6 to be verified by neutron counting methods. In association with such measurements high resolution gamma-ray spectrometry (HRGS) measurements using a high-purity Ge detector are often undertaken to determine the 235U enrichment based off the intensity of the direct 186 keV line. The specific (?,n) neutron production, neutrons per second per gram of U, is sensitive to the relative isotopic composition, particularly the 234U concentration, and the traditional gross neutron counting approach is needed to quantitatively interpret the data. In addition to F(?,n) neutrons, ?-induced reaction ?-rays are generated, notably at 110, 197, 582, 891, 1236 and 1275 keV. If one could observe 19F(?,x?) gamma-lines in the HRGS spectra the thought was that perhaps the ?-activity could be estimated directly, and in turn the 234U abundance obtained. For example, by utilizing the ratio of the detected 197-186 keV full energy peaks. However, until now there has been no readily available estimate of the expected strength of the reaction gamma-rays nor any serious consideration as to whether they might be diagnostic or not. In this work we compute the thick target yields of the chief reaction gamma-rays in UF6 using published thin target data. Comparisons are made to the neutron production rates to obtain ?/n estimates, and also to the 235U decay line at 186 keV which we take as a fiducial line. It is shown that the reaction gamma-rays are produced but are far too weak for practical safeguards purposes. Now that the underlying numerical data is readily available however, it can be used to support neutron and gamma production calculations in other fluorine compounds, for example impure plutonium reference materials where fluorine may be present only at the parts per million by weight level yet still present a serious nuisance addition to the neutron production rate.

Croft, Stephen; Swinhoe, Martyn T.; Miller, Karen A.

2013-01-01

391

GAMMA SPECTRUM ANALYSIS FOR ENVIRONMENTAL NUCLIDES  

Microsoft Academic Search

Abstract: Abstract: Abstract: Abstract: This paper is related to problems concerning thermoluminescence (TL) dating pro- cedures. In our TL dating laboratory the annual dose rates are determined from the high- resolution gamma spectrometry measurements. For spectral investigations a Canberra spec- trometer with the HPGe detector and Marinelli geometry (0.5 l capacity) with a shield is used. The method for spectral

HUBERT L. OCZKOWSKI

2001-01-01

392

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

393

Radiation Metabolomics. 3. Biomarker Discovery in the Urine of Gamma-Irradiated Rats Using a Simplified Metabolomics Protocol of Gas Chromatography-Mass Spectrometry Combined with Random Forests Machine Learning Algorithm  

PubMed Central

Radiation metabolomics employing mass spectral technologies represents a plausible means of high-throughput minimally invasive radiation biodosimetry. A simplified metabolomics protocol is described that employs ubiquitous gas chromatography-mass spectrometry and open source software including random forests machine learning algorithm to uncover latent biomarkers of 3 Gy ? radiation in rats. Urine was collected from six male Wistar rats and six sham-irradiated controls for 7 days, 4 prior to irradiation and 3 after irradiation. Water and food consumption, urine volume, body weight, and sodium, potassium, calcium, chloride, phosphate and urea excretion showed major effects from exposure to ? radiation. The metabolomics protocol uncovered several urinary metabolites that were significantly up-regulated (glyoxylate, threonate, thymine, uracil, p-cresol) and down-regulated (citrate, 2-oxoglutarate, adipate, pimelate, suberate, azelaate) as a result of radiation exposure. Thymine and uracil were shown to derive largely from thymidine and 2?-deoxyuridine, which are known radiation biomarkers in the mouse. The radiation metabolomic phenotype in rats appeared to derive from oxidative stress and effects on kidney function. Gas chromatography-mass spectrometry is a promising platform on which to develop the field of radiation metabolomics further and to assist in the design of instrumentation for use in detecting biological consequences of environmental radiation release.

Lanz, Christian; Patterson, Andrew D.; Slavik, Josef; Krausz, Kristopher W.; Ledermann, Monika; Gonzalez, Frank J.; Idle, Jeffrey R.

2009-01-01

394

Observation of gamma ray bursts and flares by the EGRET telescope on the Compton Gamma Ray Observatory  

NASA Technical Reports Server (NTRS)

The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory has observed energetic gamma ray bursts and flares. On May 3, 1991, EGRET detected a gamma ray burst both in the energy measuring NaI (Tl) scintillator and independently in the spark chamber imaging assembly. The NaI spectra were accumulated by a special BURST mode of EGRET. The spectra were measured over a range from 1 to 200 MeV, in three sequential spectra of 1,2, and 4 seconds. During the peak of the burst, six individual gamma rays were detected in the spark chamber, allowing a determination of the burst arrival direction. The intense flares of June were also detected. A solar flare on June 4 was observed to last for several minutes and for a brief time, less than a minute, had significant emission of gamma rays exceeding 150 MeV.

Schneid, E. J.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kwok, P. W.; Mattox, J. R.; Sreekumar, P.; Thompson, D. J.; Kanbach, G.

1992-01-01

395

Observation of gamma ray bursts and flares by the EGRET telescope on the Compton Gamma Ray Observatory  

NASA Astrophysics Data System (ADS)

The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory has observed energetic gamma ray bursts and flares. On May 3, 1991, EGRET detected a gamma ray burst both in the energy measuring NaI (Tl) scintillator and independently in the spark chamber imaging assembly. The NaI spectra were accumulated by a special BURST mode of EGRET. The spectra were measured over a range from 1 to 200 MeV, in three sequential spectra of 1,2, and 4 seconds. During the peak of the burst, six individual gamma rays were detected in the spark chamber, allowing a determination of the burst arrival direction. The intense flares of June were also detected. A solar flare on June 4 was observed to last for several minutes and for a brief time, less than a minute, had significant emission of gamma rays exceeding 150 MeV.

Schneid, E. J.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kwok, P. W.; Mattox, J. R.; Sreekumar, P.; Thompson, D. J.; Kanbach, G.

396

Observation of gamma ray bursts and flares by the EGRET telescope on the Compton Gamma Ray observatory  

NASA Astrophysics Data System (ADS)

The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray observatory has observed energetic gamma ray bursts and flares. On May 3, 1991, EGRET detected a gamma ray burst both in the energy measuring NaI (Tl) scintillator and independently in the spark chamber imaging assembly. The NaI spectra were accumulated by a special BURST mode of EGRET. The spectra were measured over a range from 1 to 200 MeV, in three sequential spectra of 1, 2, and 4 seconds. During the peak of the burst, six individual gamma rays were detected in the spark chamber, allowing a determination of the burst arrival direction. The intense flares of June were also detected. A solar flare on June 4 was observed to last for several minutes and for a brief time, less than a minute, had significant emission of gamma rays exceeding 150 MeV.

Schneid, E. J.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R.; Hunter, S. D.; Kwok, P. W.; Mattox, J. R.; Sreekumar, P.; Thompson, D. J.; Kanbach, G.; Mayer-Hasselwander, M. A.; von Montigny, C.; Pinkau, K.; Rothermel, H.; Sommer, M.; Kniffen, D. A.; Lin, Y. C.; Michelson, P. F.; Nolan, P. L.

1991-09-01

397

Gamma Scattering.  

National Technical Information Service (NTIS)

Experimental examinations have been performed on a gamma scattering source/detector configuration that is believed to have the potential for providing density information at a finite number of positions along the primary beam and the average attenuation a...

A. G. Baker

1980-01-01

398

Gamma Knife  

MedlinePLUS

... session. Under local anesthesia, a special rigid head frame incorporating a three-dimensional coordinate system is attached ... between the target, normal structures and the head frame to calculate Gamma Knife® treatment parameters. Targets often ...

399

Observation of infrared emission spectra from silicon combustion products  

NASA Astrophysics Data System (ADS)

The combustion of silicon based pyrotechnic compositions is observed with time resolved infrared spectrometry. This revealed the build up of strong emission at 9.1 ± 0.1 ?m, which is associated with condensed silicon dioxide particulates. Time averaged spectra for compositions containing different oxidants or binders illustrate the dependence of SiO 2 emission intensity on composition.

Smit, Kenneth J.; De Yong, Leo V.; Gray, Rodney

1996-05-01

400

Influence of phlegmatization on spectra of explosives in THz range  

Microsoft Academic Search

We report on influence of phlegmatization of two explosives: hexogen and octogen on their spectra in 0.5-5.0 THz range. Measurements were carried out by means of Fourier Transform Spectrometry. Increase in attenuation is observed for both materials.

N. Palka; M. Szustakowski; W. Ciurapinski; T. Trzcinski; P. Zagrajek

2010-01-01

401

The Spectra Count Label-free Quantitation in Cancer Proteomics  

PubMed Central

Mass spectrometry is used routinely for large-scale protein identification from complex biological mixtures. Recently, relative quantitation approach on the basis of spectra count has been applied in several cancer proteomic studies. In this review, we examine the mechanism of this technique and highlight several important parameters associated with its application.

Zhou, Weidong; Liotta, Lance A.; Petricoin, Emanuel F.

2013-01-01

402

Portable gamma-ray holdup and attributes measurements of high- and variable-burnup plutonium  

SciTech Connect

High burnup-plutonium holdup has been assayed quantitatively by low resolution gamma-ray spectrometry. The assay was calibrated with four plutonium standards representing a range of fuel burnup and {sup 241}Am content. Selection of a calibration standard based on its qualitative spectral similarity to gamma-ray spectra of the process material is partially responsible for the success of these holdup measurements. The spectral analysis method is based on the determination of net counts in a single spectral region of interest (ROI). However, the low-resolution gamma-ray assay signal for the high-burnup plutonium includes unknown amounts of contamination from {sup 241}Am. For most needs, the range of calibration standards required for this selection procedure is not available. A new low-resolution gamma-ray spectral analysis procedure for assay of {sup 239}Pu has been developed. The procedure uses the calculated isotope activity ratios and the measured net counts in three spectral ROIs to evaluate and remove the {sup 241}Am contamination from the {sup 239}Pu assay signal on a spectrum-by-spectrum basis. The calibration for the new procedure requires only a single plutonium standard. The procedure also provides a measure of the burnup and age attributes of holdup deposits. The new procedure has been demonstrated using portable gamma-ray spectroscopy equipment for a wide range of plutonium standards and has also been applied to the assay of {sup 239}Pu holdup in a mixed oxide fuel fabrication facility. 10 refs., 5 figs., 3 tabs.

Wenz, T.R.; Russo, P.A.; Miller, M.C.; Menlove, H.O. (Los Alamos National Lab., NM (United States)); Takahashi, S.; Yamamoto, Y.; Aoki, I. (Power Reactor and Nuclear Fuel Development Corp., Tokai, Ibaraki (Japan))

1991-01-01

403

Implications for High Energy Blazar Spectra from Intergalactic Absorption Calculations  

NASA Technical Reports Server (NTRS)

Given a knowledge of the density spectra intergalactic low energy photons as a function of redshift, one can derive the intrinsic gamma-ray spectra and luminosities of blazars over a range of redshifts and look for possible trends in blazar evolution. Stecker, Baring & Summerlin have found some evidence hinting that TeV blazars with harder spectra have higher intrinsic TeV gamma-ray luminosities and indicating that there may be a correlation of spectral hardness and luminosity with redshift. Further work along these lines, treating recent observations of the blazers lES02291+200 and 3C279 in the TeV and sub-TeV energy ranges, has recently been explored by Stecker & Scully. GLAST will observe and investigate many blazars in the GeV energy range and will be sensitive to blazers at higher redshifts. I examine the implications high redshift gamma-ray absorption for both theoretical and observational blazer studies.

Stecker, F

2008-01-01

404

Emission spectrometry of gases - Current status, problems, and future prospects  

NASA Astrophysics Data System (ADS)

Recent advances in the use of emission spectrometry for the analysis of gases are reviewed. Particular attention is given to the use of emission spectrometry in combination with physicochemical analytic techniques, such as gas adsorption chromatography and cryogenic collection of impurities on various sorbents. Such combined methods make it possible to determine impurities in pure gases down to 0.0001-0.00001 mol pct or less. The discussion also covers methods involving resonance excitation of analytical spectra, such as laser fluorescence, and methods based on nonresonance excitation of emission spectra i.e., Raman scattering techniques.

Bolshakov, A. A.; Nemets, V. M.; Oshemkov, S. V.; Petrov, A. A.; Solovev, A. A.

1984-04-01

405

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

406

Effect of isotopic disorder on Raman scattering spectra of crystals  

SciTech Connect

The first results of a quantitative study into the effect of isotopic disorder on optical phonon states, revealed as a broadening and shift of LO({Gamma}) phonon lines in second-order Raman scattering spectra of LiH{sub x}D{sub 1-x} crystals, are presented. The presence in the spectra of a local vibration at small values of x and the two-mode character of the LO{Gamma} phonons for x {le} 0.45, together with the substantial broadening of the LO({Gamma}) phonon scattering lines, suggest the presence of a considerable isotopic disorder effect, which implies unambiguously strong LO({Gamma}) phonon scattering. Additional supporting evidence comes from the disagreement of the above experimental finding with the coherent-potential-model predictions for the case of weak phonon scattering. 21 refs., 3 figs.

Plekhanov, V.G. [Elores Joint-Stock Company, Tallinn (Ethiopia)

1995-03-01

407

Measurement of Radionuclide Activities Induced in Target Components of an IBA CYCLONE 18/9 by Gamma-Ray Spectrometry with HPGe and LaBr3: Ce Detectors.  

PubMed

Cyclotrons are used worldwide to produce radiopharmaceuticals by proton irradiation of a suitable target. The intense secondary neutron beam generated by proton interactions with the target induce high radionuclide activities in the target assembly parts that may result in an exposure to high dose levels of the operators during maintenance. The main goal of this work is to evaluate gamma-emitting radionuclide activities induced in Havar foils and titanium windows of a target assembly and carousel stripper forks of an IBA CYCLONE 18/9 cyclotron. The knowledge of radionuclide inventory for each component is required by many companies to assess risk for operators before waste handling and disposal. Gamma-ray spectrometric analyses were carried out with High Purity Germanium (HPGe) and Lanthanum bromide (LaBr3:Ce) scintillation detectors. HPGe is the most used detector for its high energy resolution although it is more suitable for use in a laboratory. The use of LaBr3:Ce can be considered a viable option, particularly in realizing a portable spectrometric system to perform "on-site" measurements and a fast dose rate evaluation before the disposal of activated parts. Due to a high activity of target assembly components replaced after a typical irradiation cycle (about 5000 ?Ah integrated beam current), gamma-ray spectrometric measurements were performed at a large distance from the detector, even more than 100 cm, or by using a purposely realized Lead-walled collimator. The identification of some key-radionuclides allows to evaluate through simple formulations the dose rate behavior for each component as function of decay time from the last irradiation. The knowledge of the dose rate behavior is a significant piece of information to health physicists for waste handling with safety at work. For an Havar™ foil, the dose rate will be reduced to about 1/1,000 of the starting value after a decay period of approximately 4 y (about 1,500 d), with a relatively safety at product disposal work. For a longer time, only long-lived radionuclides Co, Co, and Mn contribute to dose rate. PMID:24949919

Tomarchio, Elio

2014-08-01

408

Z{gamma}{gamma}{gamma} {yields} 0 Processes in SANC  

SciTech Connect

We describe the analytic and numerical evaluation of the {gamma}{gamma} {yields} {gamma}Z process cross section and the Z {yields} {gamma}{gamma}{gamma} decay rate within the SANC system multi-channel approach at the one-loop accuracy level with all masses taken into account. The corresponding package for numeric calculations is presented. For checking of the results' correctness we make a comparison with the other independent calculations.

Bardin, D. Yu., E-mail: bardin@nu.jinr.ru; Kalinovskaya, L. V., E-mail: kalinov@nu.jinr.ru; Uglov, E. D., E-mail: corner@nu.jinr.ru [JINR, Dzhelepov Laboratory for Nuclear Problems (Russian Federation)

2013-11-15

409

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

410

Fluorescence Line-Narrowing Spectrometry: Application to the Study of Benzo(a)pyrene Metabolic Pathways.  

National Technical Information Service (NTIS)

The application of fluorescence line-narrowing spectrometry (FLNS) to the study of the pathways involved in the metabolic activation of the environmental contaminant and carcinogen benzo(a)pyrene is described. Fluorescence line-narrowed (FLN) spectra of b...

D. S. Zamzow

1988-01-01

411

LaCl 3(Ce) scintillation detector applications for environmental gamma-ray measurements of low to high dose rates  

NASA Astrophysics Data System (ADS)

A new cerium-doped LaCl 3(Ce) scintillator is evaluated with respect to the application in environmental gamma-ray dosimetry and spectrometry. The scintillator is very attractive for gamma-ray spectrometry in the case of high count rate, because it has excellent energy resolution and fast decay time. The performance characteristics of a scintillator with a 25.4 mm×25.4 mm LaCl 3(Ce) crystal are studied and compared to those of a NaI(Tl) scintillator with the same size crystal. Acquired pulse height spectra are converted to dose rates by using the G(E) function method. Though the LaCl 3(Ce) crystal itself produces a rather high background in the crystal itself, the scintillator provides good energy information and dose-rate readings from low to high-level (several mGy/h) by subtracting the self-background. The properties of LaCl 3(Ce) scintillator suggest that the scintillator could be a promising candidate for monitoring at high dose levels as in emergencies, as well as at ordinary levels of background radiation.

Tsutsumi, Masahiro; Tanimura, Yoshihiko

2006-02-01

412

Crack spectra analysis  

SciTech Connect

Crack spectra derived from velocity data have been shown to exhibit systematics which reflect microstructural and textural differences between samples (Warren and Tiernan, 1980). Further research into both properties and information content of crack spectra have yielded the following: Spectral features are reproducible even at low pressures; certain observed spectral features may correspond to non-in-situ crack populations created during sample retrieval; the functional form of a crack spectra may be diagnostic of the sample's grain texture; hysteresis is observed in crack spectra between up and down pressure runs - it may be due to friction between the faces of closed crack populations.

Tiernan, M.

1980-09-01

413

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

414

Gamma-irradiated dry fruits  

Microsoft Academic Search

EPR spectra of dry, sugar containing fruits—raisins, sultanas, figs, dates, peaches, blue plums and chokeberry recorded before and after irradiation with gamma-rays, are reported. It is shown that weak singlet EPR line with 2.0031±0.0005 can be recorded before irradiation of seeds, stones or skin of chokeberry, figs and raisins as well as flesh of blue plum, raisins and peaches. EPR

Nicola D. Yordanov; Zdravka Pachova

2006-01-01

415

Hadamard transform visible Raman spectrometry  

SciTech Connect

The successful application of LC-SLM Hadamard transform spectrometry as a simultaneous multiwavelength detection system to Raman spectroscopy is presented. Multiplexed Raman data are obtained with the use of an Ar/sup +/ laser lasing at 514.5 nm and a room-temperature silicon photodiode. A conventional 90/sup 0/ scattering geometry is employed for measurements. It is demonstrated that the LC-SLM Hadamard transform Raman spectrometer possesses the capability of performing spectral subtraction and the ability to obtain depolarization ratios of Raman bands, and can function as a selectively tunable optical filter for both Rayleigh line rejection and optical band notching. It is also demonstrated that, for the Hadamard transform Raman experiment, the silicon photodiode used as the detector produces spectra with slightly better signal-to-noise ratios than those obtained with the photomultiplier tube (PMT) used as the detector, although the PMT shows an increase in sensitivity.

Tilotta, D.C.; Freeman, R.D.; Fateley, W.G.

1987-11-01

416

Neutron spectrometry at JET (invited)  

SciTech Connect

Measurements of the energy spectra of fusion neutrons is accorded a prominent position in the neutron diagnostics program at JET. The nature of the information on plasma properties which it is hoped will be obtained is discussed, as is the availability of suitable instruments and techniques for spectrometry on thermonuclear plasmas. Of these instruments, only the /sup 3/He ionization chamber has, so far, been successfully exploited; the lessons learned regarding its performance are outlined and the results obtained for ohmically and ICRF-heated plasmas are presented. It is shown that the deuterium ion energy distributions appear to be Maxwellian for all plasmas studied, that central ion temperatures have been obtained on a shot-by-shot basis which agree well with corresponding values obtained by neutral particle analysis and that the deuteron-to-electron density ratio in the plasma is approximately 0.5.

Jarvis, O.N.; Gorini, G.; Hone, M.; Kaellne, J.; Sadler, G.; Merlo, V.; van Belle, P.

1986-08-01

417

Detection Technologies. Ambient mass spectrometry.  

PubMed

A recent innovation in mass spectrometry is the ability to record mass spectra on ordinary samples, in their native environment, without sample preparation or preseparation by creating ions outside the instrument. In desorption electrospray ionization (DESI), the principal method described here, electrically charged droplets are directed at the ambient object of interest; they release ions from the surface, which are then vacuumed through the air into a conventional mass spectrometer. Extremely rapid analysis is coupled with high sensitivity and high chemical specificity. These characteristics are advantageously applied to high-throughput metabolomics, explosives detection, natural products discovery, and biological tissue imaging, among other applications. Future possible uses of DESI for in vivo clinical analysis and its adaptation to portable mass spectrometers are described. PMID:16543450

Cooks, R Graham; Ouyang, Zheng; Takats, Zoltan; Wiseman, Justin M

2006-03-17

418

Report to the DOE nuclear data committee. [EV RANGE 10-100; CROSS SECTIONS; PHOTONEUTRONS; NEUTRONS; GAMMA RADIATION; COUPLED CHANNEL THEORY; DIFFERENTIAL CROSS SECTIONS; MEV RANGE 01-10; ; CAPTURE; GAMMA SPECTRA; THERMAL NEUTRONS; COMPUTER CALCULATIONS; DECAY; FISSION PRODUCTS; FISSION YIELD; SHELL MODELS; NUCLEAR DATA COLLECTIONS  

SciTech Connect

Topics covered include: studies of (n, charged particle) reactions with 14 to 15 MeV neutrons; photoneutron cross sections for /sup 15/N; neutron radiative capture; Lane-model analysis of (p,p) and (n,n) scattering on the even tin isotopes; neutron scattering cross sections for /sup 181/Ta, /sup 197/Au, /sup 209/Bi, /sup 232/Th, and /sup 238/U inferred from proton scattering and charge exchange cross sections; neutron-induced fission cross sections of /sup 245/Cm and /sup 242/Am; fission neutron multiplicities for /sup 245/Cm and /sup 242/Am; the transport of 14 MeV neutrons through heavy materials 150 < A < 208; /sup 249/Cm energy levels from measurement of thermal neutron capture gamma rays; /sup 231/Th energy levels from neutron capture gamma ray and conversion electron spectroscopy; new measurements of conversion electron binding energies in berkelium and californium; nuclear level densities; relative importance of statistical vs. valence neutron capture in the mass-90 region; determination of properties of short-lived fission products; fission yield of /sup 87/Br and /sup 137/I from 15 nuclei ranging from /sup 232/Th to /sup 249/Cf; evaluation of charged particle data for the ECPL library; evaluation of secondary charged-particle energy and angular distributions for ENDL; and evaluated nuclear structure libraries derived from the table of isotopes. (GHT)

Struble, G.L.; Haight, R.C.

1981-03-01

419

Binary collision rates of relativistic thermal plasmas. II - Spectra  

NASA Technical Reports Server (NTRS)

Spectra of importance for the analysis of relativistic thermal plasmas are numerically calculated assuming a thermal form for the particle distribution functions. Complete sets of optically thin thermal electron-proton, electron-electron, and electron-positron bremsstrahlung spectra are calculated throughout the transrelativistic regime of electron temperatures and compared with approximate expressions for the spectra in the nonrelativistic and extreme relativistic regimes of temperature. A method for calculating accurate secondary particle production spectra in proton-proton collisions from threshold to the highest energies is presented based on an isobaric model near threshold and scaling representations at high energies. The production spectra of charged and neutral pions resulting from proton-proton collisions in relativistic proton plasmas are calculated, and the resultant electron, positron, and gamma-ray spectra from the decay of secondary pions are presented.

Dermer, C. D.

1986-01-01

420

Study of laser resonance ionization mass spectrometry using a glow discharge source  

SciTech Connect

The mass spectra of a metal alloy sample consisting of Al, Cu and Fe were studied using both glow discharge mass spectrometry (GDMS) and resonance ionization mass spectrometry (RIMS). Particular emphasis was placed on the reduction of isobaric interferences and discrimination between those ions formed by the discharge and those formed by the laser radiation.

Xiong, X. [National Inst. of Standards and Technology, Gaithersburg, MD (United States)]|[Eastern Analytical, Inc., College Park, MD (United States); Hutchinson, J.M.R.; Fassett, J.D.; Lucatorto, T.B.; Schima, F.J.; Bowman, W.A. [National Inst. of Standards and Technology, Gaithersburg, MD (United States); Hess, K.R. [Franklin and Marshall Coll., Lancaster, PA (United States). Dept. of Chemistry

1994-09-01

421

Gamma ray bursts from magnetospheric plasma oscillations  

NASA Technical Reports Server (NTRS)

Neutron star Magnetospheric Plasma Oscillations (MPO), can account for the energetics, decay time scale, and spectra of typical Gamma Ray Bursts (GRBs). The soft photon source is likely to be due to backwarming of the reprocessing boundary by the incipient gamma rays. It is shown that the observed fraction of bursts displaying low energy absorption features may be understood in the context of an MPO model. Moreover, it is found that GRB spectra should display these cyclotron lines about 18 percent of the time, which is consistent with the KONUS and Ginga sets of data.

Melia, Fulvio

1989-01-01

422

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

423

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

424

Peptide Charge State Determination for Low-Resolution Tandem Mass Spectra  

Microsoft Academic Search

Mass spectrometry is a particularly useful technology for the rapid and robust identification of peptides and pro- teins in complex mixtures. Peptide sequences can be iden- tified by correlating their observed tandem mass spectra (MS\\/MS) with theoretical spectra of peptides from a se- quence database. Unfortunately, to perform this search the charge of the peptide must be known, and current

Aaron A. Klammer; Christine C. Wu; Michael J. Maccoss; William Stafford Noble

2005-01-01

425

Virtual Gamma Ray Radiation Sources through Neutron Radiative Capture  

SciTech Connect

The countrate response of a gamma spectrometry system from a neutron radiation source behind a plane of moderating material doped with a nuclide of a large radiative neutron capture cross-section exhibits a countrate response analogous to a gamma radiation source at the same position from the detector. Using a planar, surface area of the neutron moderating material exposed to the neutron radiation produces a larger area under the prompt gamma ray peak in the detector than a smaller area of dimensions relative to the active volume of the gamma detection system.

Scott Wilde, Raymond Keegan

2008-07-01

426

Universality of velocity spectra  

Microsoft Academic Search

The purpose of this paper is to present unified spectral models for the three-component velocity fluctuations observed in wind-tunnel generated shear flows and in the atmospheric boundary layer. Presently, only empirical models exist whose coefficients are based on the matching of these models with observed spectra. A general spectral model is presented which can be closely matched to velocity spectra

H. W. Tieleman

1995-01-01

427

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

428

Spectra of porphyrins  

Microsoft Academic Search

The review opens by presenting the absorption spectra for three series of porphyrins derived from the basic skeleton: (a) compounds obtained by simple substitution; (b) compounds obtained by reduction of one or more pyrrole rings; and (c) compounds obtained from fusion of aromatic rings onto the basic skeleton. The spectra are discussed in terms of a four orbital model-that is

Martin Gouterman

1961-01-01

429

Optical Spectra of Supernovae  

Microsoft Academic Search

The temporal evolution of the optical spectra of various types of supernovae (SNe) is illustrated, in part to aid observers classifying supernova candidates. Type II SNe are defined by the presence of hydrogen, and they exhibit a very wide variety of photometric and spectroscopic properties. Among hydrogen-deficient SNe (Type I), three subclasses are now known: those whose early-time spectra show

Alexei V. Filippenko

1997-01-01

430

GSAP: FORTRAN code for gamma-spectrum analysis.  

National Technical Information Service (NTIS)

The GSAP program performs fully automatic evaluation of gamma-ray energy spectra measured with semiconductor detectors. After the input data comprising experimental spectrum, energy and FWHM calibrations and parameters controlling the peak search are supp...

V. Hnatowicz P. Kozma V. I. Ilyushchenko

1989-01-01

431

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

432

What is Mass Spectrometry?  

NSDL National Science Digital Library

This site from the American Society for Mass Spectrometry includes information about what mass spectometry is and how it is used. It has many useful figures and references to other materials. The material answers questions such as "What is mass spectrometry and what can it do for you?"

Chiu, Chia M.

2012-09-21

433

Cascaded Gamma Rays as a Probe of Cosmic Rays  

NASA Astrophysics Data System (ADS)

Very-high-energy (VHE) and ultra-high-energy (UHE) gamma rays from extragalactic sources experience electromagnetic cascades during their propagation in intergalactic space. Recent gamma-ray data on TeV blazars and the diffuse gamma-ray background may have hints of the cascade emission, which are especially interesting if it comes from UHE cosmic rays. I show that cosmic-ray-induced cascades can be discriminated from gamma-ray-induced cascades with detailed gamma-ray spectra. I also discuss roles of structured magnetic fields, which suppress inverse-Compton pair halos/echoes but lead to guaranteed signals - synchrotron pair halos/echoes.

Murase, Kohta

2014-06-01

434

Gamma Experiment  

NSDL National Science Digital Library

This resource consists of a Java applet and expository text. The applet simulates the time of the k'th arrival in a Poisson process. The arrival number k and the rate of the Poisson process can be varied. The applet illustrates the gamma distribution and a special case of the central limit theorem.

Siegrist, Kyle

435

Gamma irradiators  

SciTech Connect

The commercial use of gamma radiation to sterilize medical equipment and supplies began in the late 1950s. This article describes the basic technology and design aspects of commercial irradiation facilities. It explains the safety features and interlocks which protect workers, the public, and the environment from radiation and radioactive material.

Cuda, J.; McKinnon, R.G. (Nordion International Inc. (US)); Baker, P.G. (Baxter/Convertors (US))

1989-02-01

436

Gamma Ray Intensity Standards for Calibrating Ge(Li) Detectors for the Energy Range 200-1700 KeV.  

National Technical Information Service (NTIS)

Gamma ray pulse height spectra for seven radioactive sources have been analyzed for the full energy peak areas. By using these areas in conjunction with the results of an extensive compilation of relative gamma ray intensities, a relatively simple efficie...

Roney W.M W. A. Seale

1978-01-01

437

EGRET Measurements of Energetic Gamma Rays from the Gamma-Ray Bursts of 1992 June 22 and 1994 March 1  

NASA Astrophysics Data System (ADS)

Energetic gamma-ray emissions from the gamma-ray bursts on 1992 June 22 (GRB 920622) and on 1994 March 1 (GRB 940301) were detected by the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (CGRO). Spectral data for both bursts were measured by EGRET's large NaI detector. Gamma rays up to