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1

FISSION PRODUCT GAMMA RAY SPECTRA  

Microsoft Academic Search

Uranium-235 fission product gamma spectra were calculated for various ; reactor operating histories. An IBM704 digital computer program was coded to ; compute the gamma energy contributed by each fission product gamma ray and to sum ; these results in energy groups. A representative curve showing the decay of ; various energy groups is presented. Comparisons are made with data

1958-01-01

2

Underground Gamma-Ray Spectrometry  

Microsoft Academic Search

Gamma-ray spectrometry using high purity Ge detectors has made significant advances in recent years because large crystals have become readily available and the importance of very radiopure materials in the construction of detectors has been understood. The combination of these improvements has made it possible to decrease detection limits in special low-background counting systems. Gamma-ray spectrometry systems located underground are

Mikael Hult; Matthias Köhler; Nova Gorica

3

Investigation of Photon Spectra and Contributions to Air Kerma Rates in the Environment near Nuclear Facilities using Portable Germanium Gamma Spectrometry  

Microsoft Academic Search

Environmental gamma ray spectra may be contributed by a number of photon sources of different energies. First, there is the contribution due to natural background: photons derived from cosmic rays present a continuum of energies but the primordial radionuclides and their decay chains (mainly 232 Th, 238 U and 40 K) produce a number of peaks at characteristic energies. 137Cs

G J Hunt

4

THE GAMMA-RAY SPECTROMETRY OF FISSION PRODUCTS. VI. THE CALCULATED AND EXPERIMENTAL GAMMA-RAY SCINTILLATION SPECTRA OF U²³⁵ FISSION PRODUCTS WITH CYLINDRICAL NaI (Tl) CRYSTALS  

Microsoft Academic Search

The calculation of scintillation spectra for the broad parallel gamma ; rays emitted from U²³⁵ fission products incident on a right circular ; cylindrical NaI (Tl) crystals is presented. Typical scintillation spectra from ; fission products are presented. The parameters of the spectra were tabulated as ; functions of time after fission. The calculated spectra with a 1.75-in.-dia x 1

Hattori

1961-01-01

5

Low-level gamma-ray spectrometry  

Microsoft Academic Search

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

R L Brodzinski

1991-01-01

6

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

7

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

8

Use of Stilbene Scintillator for gamma Spectrometry.  

National Technical Information Service (NTIS)

This report deals with the set-up and calibration of a scintillation gamma spectrometer with a single stilbene crystal, for measuring gamma spectra in the energy range from 0.5-10-MeV. The spectrometer discriminates between the measured gamma rays and the...

A. S. Makarious R. Megahid R. M. A. Maayouf

1978-01-01

9

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

10

In-flight, online processing and mapping of airborne gamma spectrometry data  

Microsoft Academic Search

Airborne gamma spectrometry is a technique especially useful for environmental monitoring and emergency preparedness. Because time is a critical factor in emergency response a fast data processing and mapping software is needed, which also supports online monitoring and data processing features. Therefore a new online data processing and mapping software was developed, which also displays successfully the gamma spectra, the

Benno Bucher; Ladislaus Rybach; Georg Schwarz

2005-01-01

11

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

12

Time resolved gamma-ray spectrometry  

Microsoft Academic Search

A new approach is proposed for the measurement of the time-dependent processes in gamma-ray spectrometry. During data acquisition,\\u000a the energy and the detection time of each event are recorded and the data are later analyzed off-line. This separation of\\u000a acquisition and data handling extends the possibilities of the analysis. A series of demonstration experiments was performed\\u000a to show the feasibility

L. Szentmiklósi; T. Belgya; G. L. Molnár; Zs. Révay

2007-01-01

13

Linssi : Database for gamma-ray spectrometry  

Microsoft Academic Search

Linssi is a Structured Query Language (SQL) database for HPGe gamma-ray spectrometry. It covers the whole production chain from\\u000a sample preparation to final analysis results. Static or mobile sampling and measurement and multiple sample types are supported.\\u000a In addition, each sample can be split or combined any number of times. A sample may be measured multiple times and each measurement

P. A. Aarnio; J. J. Ala-Heikkilä; A. Isolankila; A. Kuusi; M. Moring; M. Nikkinen; T. Siiskonen; H. Toivonen; K. Ungar; W. Zhang

2008-01-01

14

Program LEPS to Addition of gamma Spectra from Germanium Detectors.  

National Technical Information Service (NTIS)

The ''LEPS'' program, written in FORTRAN IV, performs the addition of two spectra, collected with different detectors, from the same sample. This application, adds the two gamma spectra obtained from two opposite LEPS Germanium Detectors (Low Energy Photo...

L. Romero

1986-01-01

15

Resonant Compton scattering and gamma-ray burst continuum spectra  

NASA Astrophysics Data System (ADS)

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.

1995-05-01

16

Beta and Gamma Spectra of Short-Lived Fission Products  

Microsoft Academic Search

Continuous spectra of beta particles and gamma rays emitted in the decay of short-lived fission products have been measured. These spectra, which cover the complete energy range available, can be used for checking results of detailed spectroscopic work on the decay of the nuclides studied. Another application of basic nature is the use of the beta spectra to evaluate the

G. Rudstam; P. I. Johansson; O. Tengblad; P. Aagaard; J. Eriksen

1990-01-01

17

Unfolding the response of a Ge detector used for in-situ gamma-ray spectrometry  

Microsoft Academic Search

In environmental radiation protection portable Ge detectors are used for in-situ gamma-ray spectrometry. In order to determine the complete photon fluence rate spectra including the continuum component due to photons scattered in the environment from measured pulse height distributions one needs to apply unfolding methods. A prerequisite of the unfolding is the knowledge of the response functions of the detector

Georg Fehrenbacher; Reinhard Meckbach; Peter Jacob

1996-01-01

18

An improved method for determination of heat production with gamma-ray scintillation spectrometry  

Microsoft Academic Search

Gamma-ray scintillation spectrometry is often the method of choice for determination of the heat-producing elements (HPE's) uranium, thorium and potassium. This article updates the procedure, describing modern equipment and proposing revised measurement calculations and error analysis. New equations for calculating HPE concentrations and applicable errors from gamma-ray spectra allow for standards that contain all three HPE's, rather than requiring that

Richard A. Ketcham

1996-01-01

19

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

20

Gamma-Ray Spectra of Fractionated Fission Products.  

National Technical Information Service (NTIS)

To determine the effects of fractionation on gamma-ray exposure rates in fission-product fields, spectra of gamma-rays emitted by fractionated products of thermal neutron fission of 235U were studied. Controlled fractionation was brought about by sweeping...

D. Sam L. R. Bunney

1971-01-01

21

Modeling of Ge(Li) gamma-ray spectra  

Microsoft Academic Search

The purpose of this work was to develop a model of monoenergetic gamma-ray spectra that were experimentally measured with a Ge(Li) detector counting system. A number of notable investigations have attempted all or part of this task with varying degrees of success. This model was incorporated into the FORTRAN computer program SPECTRA, which can be used to calculate the expected

R. D. Harris; S. E. Binney

1986-01-01

22

ELECTRON SPIN RESONANCE SPECTRA OF SOME $gamma$-IRRADIATED POLYMERS  

Microsoft Academic Search

The electron spin resonance spectra of a number of gamma -irradiated ; polymers, mostly of the polyvinyl series, were measured. The results are ; tabulated and the spectra are shown. The appearance of a new spectrum on ; introducing air was noted in some cases. A few tentative interpretations of the ; hyperfine patterns are made. (auth);

R. J. Abraham; D. H. Whiffen

1958-01-01

23

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

24

Monte Carlo simulations of plutonium gamma-ray spectra  

SciTech Connect

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

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

1993-07-16

25

Fission-product gamma-ray and photoneutron spectra  

Microsoft Academic Search

Fission-product gamma-ray and photoneutron spectra from thermal and fast fission of ²³³U, ²³⁵U, ²³⁸U, and ²³⁹Pu have been calculated at 27 time intervals between 1 and 1000 hours following reactor shutdown. The gamma spectral calculations were made using CINDER, a depletion and fission-product code, which has been revised, extended, and variably dimensioned for applications to many problems involving irradiated materials.

M. G. Stamatelatos; T. R. England

1975-01-01

26

Synthetic gamma-ray spectra for Homeland Security radionuclides analysis  

Microsoft Academic Search

Homeland Security applications use radiation detectors to identify radionuclides by gamma spectroscopy techniques. In order to check compliance of such systems to performance requirements, a computer code which predicts the gamma-ray spectra for various radiation detectors, as NaI(TI) and Ge was employed. The spectrum of a chosen radio-nuclide is generated according to its activity, its photo peak energy and yield

S. Levinson; B. Sarusi; A. Osovizky; V. Pushkarsky; U. German; E. Marcus; Y. Cohen; I. Belaish

2009-01-01

27

On the nature of gamma-ray burst spectra  

Microsoft Academic Search

The recent discovery of low-energy absorption features in the spectra of gamma-ray bursts (GRBs) reported by Murakami et al. (1988) is discussed in the context of a new model for gamma-ray emission in isolated neutron-star sources. It is shown that the whole GRB spectrum may be due to irradiation of a reprocessing and reflecting boundary near a source of power-law

Fulvio Melia

1988-01-01

28

Determination of depth distributions of natural radionuclides with in situ gamma-ray spectrometry  

Microsoft Academic Search

To determine natural and artificial radio-nuclide concentrations in the ground in situ gamma-ray spectrometry method based on assumptions on the depth distribution of the radionuclides. In this paper two-slab geometries with different activities are assumed and two methods to derive information on the depth distribution of natural radionuclides from the measured spectra are examined. They use the distribution dependence of

Severin Thummerer; Peter Jacob

1998-01-01

29

Scintillation gamma Spectrometry with a Stilbene Crystal.  

National Technical Information Service (NTIS)

A method of converting apparatus for amplitude dispersion to energy dispersion of gamma quanta measured with a single stilbene crystal gamma spectrometer is described. One of the main advantages of this spectrometer is the possibility of practically simul...

Y. I. Kolevatov V. I. Kukhtevich I. V. Goryachev

1969-01-01

30

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

PubMed

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 (214)Bi (1.76 MeV), (208)Tl (2.62 MeV) and (40)K (1.46 MeV). The inferred absorbed dose rate and the radon flux are estimated to be lower than 60 nGy h(-1) and 22 Bq m(-2)h(-1), respectively. PMID:19249218

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

2009-01-24

31

Gamma-Ray Output Spectra from ^239Pu Fission  

NASA Astrophysics Data System (ADS)

A new measurement of the gamma-ray energy spectrum and multiplicity following neutron-induced fission of ^239Pu has been made using DANCE, a highly-segmented, nearly 4? BaF2 array at the Los Alamos Neutron Science Center. The ^239Pu target consisted of an approximately 2 mg/cm^2 deposit mounted in a small parallel-plate avalanche chamber inserted into the DANCE in order to tag fission events. The gamma-ray spectra were measured for several strong neutron resonances below 100 eV. The measured spectra were corrected for detector response by using simple parameterizations of the actual fission gamma-ray emission coupled with a GEANT model of the DANCE array.

Ullmann, John; Jandel, Marian; Bredeweg, Todd; Couture, Aaron; Haight, Robert; O'Donnell, John; Vieira, David; Wu, Ching-Yen; Chyzh, Andrii; Gostic, Julie; Henderson, Roger; Kwan, Elaine

2011-10-01

32

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

33

Monte Carlo calculations of coincidence-summing corrections for volume sources in gamma-ray spectrometry with Ge detectors  

Microsoft Academic Search

A Monte Carlo simulation approach to solve the problem of measuring volume sources in gamma-ray spectrometry is described. The simulation package PENELOPE, with a cylindrical geometry tool was used to model two measurement systems and to calculate the detection efficiency for volume sources of ? emitters affected by coincidence-summing effects. ?-Ray spectra and experimental detection efficiencies from multi-? emitting nuclides

Eduardo García-Toraño; Milagros Pozuelo; Francesc Salvat

2005-01-01

34

Gamma spectrometry of the minor bodies of the solar system  

SciTech Connect

The authors investigate the possibility of determining the elemental composition of the surfaces of minor bodies of the solar system (asteroids, the Martian satellites Phobos and Deimos, etc.) using spacecraft-based ..gamma..-spectrometry. The dependence of ..gamma..-photon flux on altitude above the body was calculated for body radii from 13 to 500 km. Estimates were made of the sensitivity of the determination of basic rock-forming elements with respect to changes in geometry of a factor of two, using ..gamma..-spectrometry with a 100 mm by 100 mm crystal of NaI(Tl). Finally, the time required to determine the stipulated characteristic ..gamma..-radiation of surface rocks with the given precision was derived as a function of altitude.

Surkov, Yu.A.; Moskaleva, L.P.; Manvelyan, O.S.

1987-01-01

35

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

36

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

37

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

38

A cold absorption model of gamma ray burst spectra  

SciTech Connect

Motivated by the lack of x-rays below [similar to]200 keV in most GRB spectra, we consider a spectral model in which an underlying source of power-law of gamma rays is shielded by an optically thick layer of absorbing circumburster material rich in iron-group elements whose photoelectric opacity exceeds Thomson opacity below [similar to]200 keV. For reasonable distributions of line-of-sight optical depths we find that the absorbed spectrum can indeed mimic the typical observed GRB spectra.

Liang, E.P. (Department of Space Physics and Astronomy, Rice University, Houston, Texas 77251-1892 (United States))

1994-07-01

39

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

40

Power Density Spectra of Gamma-Ray Bursts  

Microsoft Academic Search

Power density spectra (PDSs) of long gamma-ray bursts (GRBs) provide useful information on GRBs, indicating their self-similar temporal structure. The best power-law PDSs are displayed by the longest bursts (T90>100 s) in which the range of self-similar timescales covers more than 2 decades. Shorter bursts have apparent PDS slopes more strongly affected by statistical fluctuations. The underlying power law can

Andrei M. Beloborodov; Boris E. Stern; Roland Svensson

2000-01-01

41

Power density spectra of gamma-ray bursts  

Microsoft Academic Search

The longest gamma-ray bursts (GRBs) display power-law power density spectra (PDSs). Shorter bursts have PDSs more strongly affected by statistical fluctuations. The underlying power law can then be reproduced with high accuracy by averaging the PDSs for a large sample of bursts. It indicates that different GRBs are random realizations of the same stochastic process. The power-law PDS provides a

Andrei M. Beloborodov; Boris E. Stern; Roland Svensson

2000-01-01

42

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

43

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

44

Low-level single and coincidence gamma-ray spectrometry  

Microsoft Academic Search

Analyses of anthropogenic and natural gamma-ray emitters in the environment require high sensitive detector systems operating\\u000a in coincidence-anticoincidence modes. Thanks to an excellent energy resolution and a high efficiency, large volume HPGe detectors\\u000a have been widely used in low-level gamma-ray spectrometry. In the present paper we discuss the characteristics of single and\\u000a coincidence (HPGe-NaI(Tl)) arrangements suitable for analysis of environmental

I. Sýkora; M. Ješkovský; R. Janik; K. Holý; M. Chudý; P. P. Povinec

2008-01-01

45

Low-level gamma spectrometry using beta coincidence and Compton suppression  

Microsoft Academic Search

A low-level gamma-ray spectrometry system was developed using a Ge(Li) detector with 6% relative efficiency coupled to a 2? beta plastic detector for coincidence selection and a massive NaI(Tl) detector for Compton suppression.The integral background count rate for (50–1500)keV was 0.5s?1kg?1 (Ge), using only beta coincidences. With Compton suppression, a value of 0.25s?1kg?1 (Ge) was obtained. Spectra with and without

E. L Grigorescu; P. De Felice; Anamaria-Cristina Razdolescu; A Luca

2004-01-01

46

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

PubMed

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

Osvath, I; Povinec, P P

2001-01-01

47

Power Density Spectra of Gamma-Ray Bursts  

Microsoft Academic Search

Power density spectra (PDSs) of long gamma-ray bursts provide useful\\u000ainformation on GRBs, indicating their self-similar temporal structure. The best\\u000apower-law PDSs are displayed by the longest bursts (T_90 > 100 s) in which the\\u000arange of self-similar time scales covers more than 2 decades. Shorter bursts\\u000ahave apparent PDS slopes more strongly affected by statistical fluctuations.\\u000aThe underlying power

Andrei M. Beloborodov; BORIS E. STERN; ROLAND SVENSSON

1999-01-01

48

Analysis of gamma ray burst spectra with cyclotron lines  

SciTech Connect

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 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. 20 refs., 8 figs., 2 tabs.

Kargatis, V. (Rice Univ., Houston, TX (USA). Dept. of Space Physics and Astronomy); Liang, E.P. (Lawrence Livermore National Lab., CA (USA))

1990-09-26

49

Cascade summing effects in close geometry gamma-ray spectrometry  

Microsoft Academic Search

Low-level gamma-ray spectrometry, particularly in underground laboratories, is used to measure radioactivity in diverse close geometries, often placing samples directly on the detector which favours strong cascade summing effects. Monte-Carlo modelling of the efficiency is extended to cascade summing effects from complete decay sequences including positron emitting radionuclides. The effect of geometrical uncertainties on the overall uncertainty is presented. The

Peter N. Johnston; Mikael Hult; Joël Gasparro

2006-01-01

50

Carborne gamma-ray spectrometry. Calibration and applications  

Microsoft Academic Search

Calibration of carborne gamma-ray spectrometry systems for 137Cs is carried out with a source successively placed at 791 positions within an area of 34m×62m. A computer model supplements the measurements. Hereby a sensitivity map for a surface contamination is generated as well as line and area sensitivities. Another model converts surface sensitivity to sensitivity for a deep contamination. Use of

H. K. Aage; U. Korsbech; K. Bargholz; J. Hovgaard

2006-01-01

51

GESPECOR: A versatile tool in gamma-ray spectrometry  

Microsoft Academic Search

GESPECOR is a Monte Carlo based software developed for the computation of efficiency, of matrix effects and of coincidence summing effects in gamma-ray spectrometry. GESPECOR can be applied to coaxial and well-type HPGe or to Ge(Li) detectors and to various types of sources, including point, cylindrical, and spherical sources or Marinelli beakers. In this paper the structure of GESPECOR is

O. Sima; D. Arnold; C. Dovlete

2001-01-01

52

Radon gamma-ray spectrometry with YAP:Ce scintillator  

Microsoft Academic Search

The detection properties of a YAP:Ce scintillator (YAlO3:Ce crystal) optically coupled to a Hamamatsu H5784 photomultiplier with standard bialkali photocathode have been analyzed. In particular, the application to radon and radon-daughters gamma-ray spectrometry was investigated. The crystal response has been studied under severe extreme conditions to simulate environments of geophysical interest, particularly those found in geothermal and volcanic areas. Tests

Wolfango Plastino; Pierino De Felice; Francesco de Notaristefani

2002-01-01

53

Multigroup beta and gamma Spectra of Individual Endf/B-IV Fission-Product Nuclides.  

National Technical Information Service (NTIS)

Delayed beta and gamma group-energy spectra were calculated for 180 individual fission-product nuclides having spectral data in ENDF/B-IV fission-product files. The beta spectra, in uniform-grid 75-group structure, and the gamma spectra, in uniform-grid 1...

T. R. England M. G. Stamatelatos

1976-01-01

54

Pulsed Bremsstrahlung Interrogation with Photoneutron - Gamma-Ray Spectrometry for Nondestructive Evaluation  

NASA Astrophysics Data System (ADS)

A novel photoneutron-based nondestructive evaluation (NDE) technique which does not require a radioactive neutron source is presented. Some unique features of this technique include: 1) pulsed interrogation neutron production within, or very near, an inspected object, 2) spectrum tailoring of the source neutrons, and 3) compatibility with many existing high-energy, commercial x-ray inspection devices. Basic concept feasibility was first established by numerical methods. The pulsed photoneutron inspection technique performs nondestructive elemental analysis using gamma-ray spectrometry. Highly penetrating bremsstrahlung photons are produced by a pulsed electron accelerator capable of producing up to 16-MeV electrons. The photoneutrons are generated by the bremsstrahlung photons interacting with an inspected object and near-by beryllium metal. The interactions of the neutrons within an inspected item result in the emission of elemental characteristic gamma-rays. Spectrometry is performed by analyzing the gamma -rays acquired between accelerator pulses. A unique fast detection and acquisition system, using two 5.08 x 5.08 -cm organic scintillators, acquires gamma-ray emissions within 100 ns of each accelerator pulse. The fast system is capable of processing individual gamma-ray signals at count rates up to 40 MHz between accelerator pulses with a repetition rate up to 1 kHz. The system incorporates a unique x-ray flash recovery method which allows individual gamma-ray detection as soon as 75 ns after the start of each x-ray flash occurring within the detector. Conventional detection and data acquisition systems are used to acquire gamma-ray spectra for the time period between 1000 ns and the next accelerator pulse. Operational tests using a 30-ps pulse width, electron accelerator demonstrated the x-ray flash recovery methodology, gamma-ray detection, and data acquisition. Although, gamma -ray spectrometry performance was limited by x-ray flash -induced gain shifts in the photomultiplier tubes, the basic NDE concept was successfully demonstrated using a modified high-purity germanium detection system.

Jones, James Litton

55

Monte Carlo calculations of coincidence-summing corrections for volume sources in gamma-ray spectrometry with Ge detectors  

NASA Astrophysics Data System (ADS)

A Monte Carlo simulation approach to solve the problem of measuring volume sources in gamma-ray spectrometry is described. The simulation package PENELOPE, with a cylindrical geometry tool was used to model two measurement systems and to calculate the detection efficiency for volume sources of ? emitters affected by coincidence-summing effects. ?-Ray spectra and experimental detection efficiencies from multi-? emitting nuclides as 60Co, 88Y, 134Cs, 152Eu and 166mHo are compared to the simulation results.

García-Toraño, Eduardo; Pozuelo, Milagros; Salvat, Francesc

2005-06-01

56

The use of commercial glass as a potential gamma accidental dosimeter through the absorption spectra  

NASA Astrophysics Data System (ADS)

Various types of commercial glass (ordinary windows, cathode ray tubes, glass kitchenware) have been studied as potential accidental radiation dosimeters. The proposed method utilizes the changes in the glasses' absorption spectra as a result of irradiation.A 60Co gamma irradiation cell has been used to irradiate samples with doses ranging from 5 to 200 Gy. The transmittance was measured using a photospectrometer (UV-visible spectrometry).The results demonstrate that the transmittance spectra of most of the glass samples change in linear proportion to the exposure dose. Moreover, the study considers the fading effect on the absorption spectra of the irradiated samples for fading times up to 100 days at room temperature.The results of this work demonstrate that several widely used types of glass can be used as high-dose accidental dosimeters for doses ranging between 8 and 200 Gy. A reasonable calibration line can be established for any irradiated glass sample by heating, re-irradiating with standard doses and measuring the related absorption coefficient.Further investigations are needed to decrease the minimum detectable dose of the proposed method and to study the effect of glass composition on radiation response.

Kharita, M. H.; Yousef, S.; Bakr, S.

2012-05-01

57

Dating the age of a nuclear event by gamma spectrometry.  

PubMed

The age of a nuclear event can be determined by measuring the activity of two fission products. The event studied was a short irradiation, of a small sample of uranium, in a nuclear reactor. Two types of a clock were investigated: non-isobaric and isobaric parent-daughter fission products. Measurements of the source by gamma spectrometry yielded very good agreement between true and measured ages. The accuracy of each clock and the upper and lower age limits of applicability were studied. PMID:14987642

Nir-El, Y

58

In-situ gamma spectrometry in environmental monitoring.  

PubMed

In-situ gamma spectrometry (scintillation or semiconductor) can be used effectively for monitoring natural and man-made radionuclide concentrations, together with the corresponding photon fields, in the environment and in workplaces. It is applied in operational and emergency monitoring of nuclear facilities, waste storage facilities and the uranium industry, in radioactive contamination measurements and mapping, environmental, radiohygienic and radiation safety studies, etc. Methods for processing and interpreting data, experimental techniques (ground or airborne arrangement), calibration and verification and examples of applications are discussed in this paper. PMID:20022255

Kluson, J

2009-11-26

59

The quality control in the production of spiked reference materials for gamma-ray spectrometry  

Microsoft Academic Search

Following a EUROMET project for the development of a range of spiked reference materials for gamma-ray spectrometry, a number of new techniques were adopted at ENEA for the routine production of these materials. A quality control of the produced samples was simultaneously started. It is based on HPGe gamma-ray spectrometry of the different samples in Marinelli beaker measuring geometry. Within

Pierino De Felice; Dadong Iskandar; Aldo Fazio; Roberto Biagini

1998-01-01

60

MCNP modelling of scintillation-detector gamma-ray spectra from natural radionuclides.  

PubMed

gamma-ray spectra of natural radionuclides are simulated for a BGO detector in a borehole geometry using the Monte Carlo code MCNP. All gamma-ray emissions of the decay of 40K and the series of 232Th and 238U are used to describe the source. A procedure is proposed which excludes the time-consuming electron tracking in less relevant areas of the geometry. The simulated gamma-ray spectra are benchmarked against laboratory data. PMID:12201154

Hendriks, P H G M; Maucec, M; de Meijer, R J

2002-09-01

61

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

Microsoft Academic Search

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

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

2011-01-01

62

Calculation of the delayed gamma-ray energy spectra from aggregate fission product nuclides  

Microsoft Academic Search

The beta-delayed emission process of gamma rays was treated with a gross theory of beta decay and a cascade gamma transition model. The method proposed was applied to calculations of the delayed gamma-ray energy spectra for short-lived fission product nuclides that lack experimental information on their gamma-ray transition properties. The calculated results are used to complement the summation calculation of

T. Yoshida; J. Katakura

1986-01-01

63

Monitoring radioactive plumes by airborne gamma-ray spectrometry  

SciTech Connect

Airborne gamma-ray spectrometer surveys using large volume sodium-iodide detectors are routinely flown throughout the world for mineral exploration and geological mapping. Techniques have now been developed to detect and map man-made sources of radiation. In Canada, airborne gamma-rays surveys have been flown around nuclear reactors to map {sup 41}Ar plumes from nuclear reactors and to calculate the dose rate at ground level. In May 1986, the Finnish Geological survey aircraft flew through a radioactive plume from the Chernobyl nuclear accident. As the aircraft flew through the plume, the aircraft became increasingly contaminated. By measuring the final aircraft contamination, the activity of the plume could be separated from the contamination due to the aircraft. Within 1 h of encountering the plume, the aircraft activity was comparable to the maximum levels found in the plume. From an analysis of the gamma-ray spectra, the concentration of {sup 131}I and {sup 140}La within the plume were calculated as a function of time.

Grasty, R.L. [Exploranium, Mississauga, Ontario (Canada); Hovgaard, J. [Danish Emergency Management Agency, Birkerod (Germany); Multala, J. [Geological Survey of Finland, Espoo (Finland)

1996-06-01

64

Low-level gamma spectrometry using beta coincidence and Compton suppression.  

PubMed

A low-level gamma-ray spectrometry system was developed using a Ge(Li) detector with 6% relative efficiency coupled to a 2pi beta plastic detector for coincidence selection and a massive NaI(Tl) detector for Compton suppression. The integral background count rate for (50-1500)keV was 0.5 s(-1)kg(-1) (Ge), using only beta coincidences. With Compton suppression, a value of 0.25 s(-1)kg(-1) (Ge) was obtained. Spectra with and without Compton suppression were studied for 60Co, 137Cs and 152Eu point sources. Considerations are made concerning the Compton suppression advantages in different situations. PMID:15177343

Grigorescu, E L; De Felice, P; Razdolescu, Anamaria-Cristina; Luca, A

65

Mars vs. the Moon: The gamma-ray and neutron spectrometry perspective  

NASA Astrophysics Data System (ADS)

The contrast in composition is fainter on Mars than on the Moon, making it hard to trace back to regional provinces on Mars, while three distinctive terranes were identified on the Moon. Distributions of bulk chemical elements at the surface are crucial clues to infer the history of the planet; they help in determining the level of fractionation, the existence of reservoirs, and the evolution that lead to the present state of its surface. There are some evidences that the early differentiation of Mars was different from the Moon, in particular in terms of resulting surface materials being more uniform. The Martian crust is also intensely marked by volcanism activity at larger scales than on the Moon. In this context it is advantageous to combine the distributions of various chemical elements to delineate the places showing coherent trends. Gamma-ray spectrometry and neutron spectrometry are now part of the standard set of remote observations of terrestrial planets. We propose to review the latest results from Lunar Prospector for the Moon and from Mars Odyssey for Mars in the perspective of geochemical province definitions. One objective would be to use similar analysis tools (such as a principal component analysis) to emphasize similarities and differences between the Moon and Mars. Lunar Prospector gamma-ray spectra were analyzed to construct maps of Th and Fe, and these data are currently reprocessed to possibly obtain maps of K, Si, Al, Mg, Ti, O, U, H, and Ca. We already have shown that the first two elements (Th and Fe) are very good indicators of the three major Lunar terranes through a covariance analysis. Maps of Fe, Th, K, H, Cl, and Si distributions at the surface of Mars were derived from a recent reprocessing of Mars Odyssey gamma-ray data including appropriate corrections, normalization, and spatial distribution. In the past we combined these datasets with neutron observations to define four large provinces that show distinctive geochemical signatures.

Gasnault, O.; Mars Odyssey; Lunar Prospector GRS Teams

66

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

Microsoft Academic Search

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 multiple 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

P. A. Baedecker; J. N. Grossman

1995-01-01

67

Utilization of the PC for analysis of gamma-ray spectra for reactor applications  

Microsoft Academic Search

A computer program has been developed for using the IBM PC and PC compatibles for gamma-ray spectrum analysis, including computation of photopeak areas from high-resolution spectra, identification of radioisotopes, and computation of absolute activity, based on absolute detector efficiency calibration. The program utilizes the direct transfer of gamma-ray spectra from any multichannel pulse-height analyzer with RS-232 serial output into the

George W

1986-01-01

68

Energy spectra of secondary gamma rays at different atmospheric depths  

Microsoft Academic Search

The CERN Intersecting Storage Ring (ISR) data for p + p - neutral pion + X inclusive reaction have been used to derive the spectrum of secondary gamma rays at the top of the atmosphere. The measured primary nucleon spectrum of the Goddard Space Flight Group has been taken as a nucleon source spectrum. Using the cascade theory, the gamma

D. P. Bhattacharyya; R. K. Roychoudhury

1979-01-01

69

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

70

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

NASA Astrophysics Data System (ADS)

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

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

1980-10-01

71

Coincidence-summing correction equations in gamma-ray spectrometry with p-type HPGedetectors  

NASA Astrophysics Data System (ADS)

Equations to compute ?-? and ?-XK coincidence-summing corrections in gamma-ray spectrometry with p-type HPGe detectors are reported. For point sources only full-energy-peak and total efficiencies are needed.

Tomarchio, E.; Rizzo, S.

2011-03-01

72

The limits of decision, detection, and determination in anti-Compton gamma-ray spectrometry  

Microsoft Academic Search

The improvement in the limits of decision, detection, and determination effected by anti-Compton gamma-ray spectrometry are considered. A simple procedure for the experimental determination is presented.

H. A. Das

1986-01-01

73

Estimation of Beta and Gamma-Ray Spectra for JENDL FP Decay Data File  

Microsoft Academic Search

Beta- and gamma-ray spectra of fission product nuclides were estimated by a theoretical model for the nuclides having no or incompletely measured spectral data. The estimation was performed with Gross Theory of Beta Decay. The estimated spectra were so stored in JENDL FP Decay Data File 2000 as to keep the consistency between the average decay energy value derived from

Jun-ichi KATAKURA; Tadashi YOSHIDA; Kazuhiro OYAMATSU; Takahiro TACHIBANA

2001-01-01

74

Fission-Product Gamma-Ray and Photoneutron Spectra and Energy-Integrated Sources Informal Report.  

National Technical Information Service (NTIS)

Fission-product gamma-ray and photoneutron spectra resulting from thermal and/or fast fission of 232Th, 233U, 235U, 238U, 239Pu, and 241Pu have been calculated at a number of times following fission. Reported here are spectra at 1, 10, 100, 1000, and 5000...

M. G. Stamatelatos T. R. England

1977-01-01

75

Janus Probe, a Detection System for High Energy Reactor gamma-Ray Spectrometry.  

National Technical Information Service (NTIS)

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 ga...

R. Gold B. J. Kaiser

1980-01-01

76

Inversion of neutron\\/gamma spectra from scintillator measurements  

Microsoft Academic Search

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

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

2011-01-01

77

THE GAMMA-RAY SPECTROMETRY OF FISSION PRODUCTS. V. GAMMA-RAY SPECTROMETRIC ANALYSIS OF FALLOUT SAMPLES  

Microsoft Academic Search

The gamma spectrometric method for the analysis of fission products was ; applied to some fall-out samples. They included snow, dust in the open air, and ; ashes of plants. Comparison was made between the apparent ages of samples from ; the experimental gamma -ray spectra with those from the beta decay curves of ; the same samples. The agreement

Hattori

1961-01-01

78

Accounting for spatial variability and fields of view in environmental gamma ray spectrometry  

Microsoft Academic Search

Spatial variability is an important feature in many environmental studies, which influences comparison estimates of environmental radioactivity from soil samples and in-situ or airborne ?-ray spectrometry. Comparisons between ground based and airborne gamma ray spectrometry are needed both for interpretation and for calibration purposes. However, under normal environmental conditions such comparisons may be affected by the considerable differences in the

A. N. Tyler; D. C. W. Sanderson; E. M. Scott; J. D. Allyson

1996-01-01

79

Recovering of the energy spectra of electrons and gamma rays coming from the thunderclouds  

NASA Astrophysics Data System (ADS)

Strong electric fields inside thunderclouds give rise to enhanced fluxes of high-energy electrons and, consequently, gamma rays and neutrons. During thunderstorms at Mount Aragats, hundreds of Thunderstorm Ground Enhancements (TGEs) comprising millions of energetic electrons and gamma rays, as well as neutrons, were detected at Aragats Space Environmental Center (ASEC) on 3200 m altitude. Observed large TGE events allow for the first time to measure the energy spectra of electrons and gamma rays well above the cosmic ray background. The energy spectra of the electrons have an exponential shape and extend up to 30-40 MeV. Recovered energy spectra of the gamma rays are also exponential in energy range 5-10 MeV, then turns to power law and extends up to 100 MeV.

Chilingarian, Ashot; Mailyan, Bagrat; Vanyan, Levon

2012-10-01

80

Neutron and gamma-ray spectra of 239PuBe and 241AmBe.  

PubMed

Neutron and gamma-ray spectra of 239PuBe and 241AmBe were measured and their dosimetric features were calculated. Neutron spectra were measured using a multisphere neutron spectrometer with a 6LiI(Eu) scintillator. The 239PuBe neutron spectrum was measured in an open environment, while the 241AmBe neutron spectrum was measured in a closed environment. Gamma-ray spectra were measured using a NaI(Tl) scintillator using the same experimental conditions for both sources. The effect of measuring conditions for the 241AmBe neutron spectrum indicates the presence of epithermal and thermal neutrons. The low-resolution neutron spectra obtained with the multisphere spectrometer allows one to calculate the dosimetric features of neutron sources. At 100 cm both sources produce approximately the same count rate as that of the 4.4 MeV gamma-ray per unit of alpha emitter activity. PMID:12150274

Vega-Carrillo, Héctor René; Manzanares-Acuña, Eduardo; Becerra-Ferreiro, Ana María; Carrillo-Nuñez, Aureliano

2002-08-01

81

MALDI-TOF mass spectrometry: Obtaining reliable mass spectra for insoluble carbonaceous pitches  

Microsoft Academic Search

The insolubility of high molecular weight (MW) carbonaceous pitches (e.g. mesophases) in even aggressive solvents has always been a significant obstacle to their MW characterization. By using matrix-assisted, laser desorption\\/ionization time-of-flight (MALDI-TOF) mass spectrometry with the matrix 7,7,8,8-tetracyanoquinodimethane (TCNQ), we are now able to obtain reproducible, highly resolved mass spectra for insoluble pitches. A solvent-free sample preparation technique was developed

Willam F Edwards; Liwen Jin; Mark C Thies

2003-01-01

82

EFFTRAN—A Monte Carlo efficiency transfer code for gamma-ray spectrometry  

Microsoft Academic Search

An implementation of the efficiency transfer method for cylindrical samples in gamma-ray spectrometry is presented, based on a Monte Carlo integration of the interaction probabilities of gamma rays over the detector and sample volumes. This approach makes it possible for the computer code to be relatively straightforward to write and the speed of the calculation to be adequate for routine

Tim Vidmar

2005-01-01

83

In situ gamma-ray spectrometry for the measurement of uranium in surface soils  

Microsoft Academic Search

The application of the technique of in situ gamma-ray spectrometry to the measurement of uranium isotopes in surface soils is described. A basic review of the in situ methodology using high resolution germanium gamma-ray spectrometers is given and specifics on calculated fluences, dose rates in air, and calibration factors are provided for relevant uranium isotopes and their progeny. The influence

K. M. Miller; P. Shebell; G. A. Klemic

1994-01-01

84

Corrections for self-attenuation in gamma-ray spectrometry of bulk samples  

Microsoft Academic Search

On the basis of the measurement of over 70 radioactive standard bulk sources with different matrix density and different shapes, the gamma-ray self-attenuation corrections needed in activity determination by means of gamma-ray spectrometry are evaluated. The full-energy peak efficiency dependence on the density, and the self-attenuation correction dependence on the photon energy are described.

T Boshkova; L Minev

2001-01-01

85

Gamma-ray Spectra and the Extragalactic Background Light  

NASA Astrophysics Data System (ADS)

Attenuation of very high-energy gamma rays by pair-production with UV, optical and IR extragalactic background light (EBL) photons provides a link between the history of galaxy formation and gamma-ray astronomy. We present results from our latest semi-analytic models (SAMs), which employ the main ingredients thought to be important to galaxy formation and evolution, as well as an improved method for reprocessing of starlight by dust to mid- and far-IR wavelengths. These SAMs are based upon a hierarchical structural formation scenario, and are successful in reproducing a large variety of observational constraints such as number counts, redshift-dependent luminosity and mass functions, and color bimodality. Our fiducial model is based upon a WMAP5 cosmology and estimates the dust emission spectral energy distribution using templates based on Spitzer data. This model predicts a background flux considerably lower than found in optical and near-IR measurements that rely on subtraction of zodiacal and galactic foregrounds, and near the lower bounds set by number counts of resolvable sources at many wavelengths. We show predictions for the effect on extragalactic gamma-ray observations, and conclude with a discussion of the implications of our work and how the science of gamma-ray astronomy will continue to help constrain cosmology.

Gilmore, Rudy; Somerville, Rachel; Primack, Joel; Domínguez, Alberto

2012-03-01

86

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

87

Gamma-ray light curves and spectra of models for Type IA supernovae  

NASA Astrophysics Data System (ADS)

Based on detailed Monte Carlo calculations, we present gamma-ray energy deposition functions, gamma-ray light curves, and gamma-ray spectra for a large set of theoretical models of Type Ia supernovae including 'classical' detonation and deflagration, delayed detonation, explosions of low mass white dwarfs, and tamped detonation scenarios. Our computations show that models for Type Ia supernovae can be discriminated and the absolute amount of Ni-56 synthesized in the event can be determined on the basis of the gamma-ray light curves and spectra if gamma-ray measurements are combined with observations at other wavelengths, e.g., in the optical band. We discuss at which times gamma-ray observations are most suitable and needed from the theoretical point of view. The implication of the upper limit in the gamma-ray flux by Compton Gamma-Ray Observatory (CGRO) experiment for our understanding of SN 1991T is discussed. We find that this limit is consistent with both the optical light curve and the implied distance (12.5 Mpc), i.e., several models can be ruled out by the gamma-ray observations.

Hoeflich, P.; Khokhlov, A.; Mueller, E.

1994-06-01

88

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

89

The very high energy gamma-ray spectra of AGN  

Microsoft Academic Search

A total of six extragalactic objects have been detected so far at very high energies (VHE). They are BL Lac objects, a sub-group of active galactic nuclei characterized by intense nonthermal radiation. The VHE spectra of two of these, 1ES 1959 + 650 and 1ES 2344 + 514, were measured in this work. Similar to the other four BL Lacs

Martin Schroedter

2004-01-01

90

Remote acquisition of gamma-ray pulse height spectra  

Microsoft Academic Search

The acquisition of pulse height spectra data in the industrial ; environment has traditionally evolved along two paths. The first required the ; transporting of a radioactive sample from the place of production to a computer ; system for counting and analysis. This method results in a degradation of the ; data due to the time delay between sample production

E. W. Killian; R. L. Heath

1975-01-01

91

An iron absorption model of gamma-ray burst spectra  

Microsoft Academic Search

Most gamma-ray bursts (GRBs) exhibit deficits of X-rays below approximately 200 keV. Here we consider a spectral model in which the burst source is shielded by an optically thick layer of circumburster material (CBM) rich in iron-group elements whose photoelectric absorption opacity exceeds the Thomson opacity below approximately 120 keV. For power-law distributions of absorption depths along the lines of

Edison P. Liang; Vincent E. Kargatis

1994-01-01

92

Gamma-ray spectra of individual components of decay series  

NASA Astrophysics Data System (ADS)

In order to obtain high quality spectra to update the ``Heath Catalog" of spectra with Ge detectors, we (I and a group of Univ. of Michigan undergraduates*) have investigated the neutron activation and decay products related to natural thorium and natural uranium. We have used the UM Ford Nuclear Reactor for irradiations and the UM Phoenix Memorial Lab for the remaining work. Spectra have been obtained with a variety of detectors, some suitable for low energies (>5 keV) and others efficient (70%) for high energies. Sources have been obtained in a variety of forms, each of which has been characterized in comparison with a thin, point source. We will report on A=233 (Th, Pa, and U, and the Np-237 parent of Pa-233), A=234 (Th and the Pa isomers), and A=239 (U, Np, and the Am-243 parent of Np-239). *The 2000-01 undergrad research group consists of Jason Banker, Adam Berro, Adam Cole, Amelia Deschamps, Erik Epp, Ralph Pierre, and Emma Wong.

Griffin, Henry

2001-04-01

93

Gamma-ray spectra and energy deposition for type IA supernovae  

Microsoft Academic Search

The standard model for supernovae of Type Ia (SNIa) involves the synthesis of radioactive 56Ni, and it is the energy deposited by the gamma-rays released in the subsequent decays that is believed to power the light curve. The authors present the results of Monte Carlo calculations of the gamma-ray spectra for a grid of models that spans the parameter space

Kailash Ambwani; Peter Sutherland

1988-01-01

94

Wide range energy spectra of hadrons and gamma-rays at the airplane altitude  

Microsoft Academic Search

The measurement of cosmic-ray spectra on the airplane has been carried out with emulsion chamber. The hadronic component together with the gamma-ray component are observed in the energy regime of 30 GeV - 40 TeV. The difference in the power exponents of hadrons and gamma-rays is observed in the energy region exceeding several hundred GeV

Y. Takahashi; J. Iwai; T. Ogata; I. Ohta

1980-01-01

95

Experimentally determined neutron and gamma-ray spectra from an encapsulated CmâOâ power source  

Microsoft Academic Search

The experimentally determined neutron and gamma ray spectra of a Cm\\/sub ;\\u000a 2\\/Oâ spontaneously fissioning source are presented. The neutron spectrum ;\\u000a is given for the energy range 30 keV to 10 MeV, while the gamma ray spectrum ;\\u000a spans the energy range 205 keV to 12 MeV. (auth)

Freestone; R. M. Jr

1974-01-01

96

An MS-DOS-based program for analyzing plutonium gamma-ray spectra  

Microsoft Academic Search

A plutonium gamma-ray analysis system that operates on MS-DOS-based computers has been developed for the International Atomic Energy Agency (IAEA) to perform in-field analysis of plutonium gamma-ray spectra for plutonium isotopics. The program titled IAEAPU consists of three separate applications: (1) a data-transfer application for transferring spectral data from a CICERO multichannel analyzer to a binary data file, (2) a

W. D. Ruhter; W. M. Buckley

1989-01-01

97

An MS-DOS-based program for analyzing plutonium gamma-ray spectra  

Microsoft Academic Search

A plutonium gamma-ray analysis system that operates on MS-DOS-based computers has been developed for the International Atomic Energy Agency (IAEA) to perform in-field analysis of plutonium gamma-ray spectra for plutonium isotopics. The user interacts with the system by means of menus and screens that allow the user to select various applications and to enter information pertinent to a measurement. This

W. D. Ruhter; W. M. Buckley

1989-01-01

98

An MS-DOS-based program for analyzing plutonium gamma-ray spectra  

Microsoft Academic Search

A plutonium gamma-ray analysis system that operates on MS-DOS-based computers has been developed for the International Atomic Energy Agency (IAEA) to perform in-field analysis of plutonium gamma-ray spectra for plutonium isotopics. The program titled IAEAPU consists of three separate applications: a data-transfer application for transferring spectral data from a CICERO multichannel analyzer to a binary data file, a data-analysis application

W. D. Ruhter; W. M. Buckley

1989-01-01

99

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

Microsoft Academic Search

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

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

1976-01-01

100

Line formation and variability in spectra of gamma-ray bursts  

NASA Astrophysics Data System (ADS)

The evolution of Gamma Ray Bursts (GRB) spectra of the events with soft absorption components show a surprising uniformity: spectra always evolve from a strong absorption to a fainter one, which finally may disappear at all. This behavior is difficult to interpret in a cyclotron model, but is naturally explained in a model of absorption in the expanding cloud, where heavy elements - products of nuclear fission - produce the observed absorption lines.

Bisnovatyi-Kogan, G. S.

1993-01-01

101

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

Microsoft Academic Search

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

D. Band; J. Matteson; L. Ford; B. Schaefer; D. Palmer; B. Teegarden; T. Cline; M. Briggs; W. Paciesas; G. Pendleton; G. Fishman; C. Kouveliotou; C. Meegan; R. Wilson; P. Lestrade

1993-01-01

102

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

NASA Astrophysics Data System (ADS)

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

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

2009-11-01

103

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

PubMed

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

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

2009-10-28

104

Energy Calibration of Gamma Spectra in Plastic Scintillators using Compton Kinematics  

SciTech Connect

This paper describes a simple and practicable method for assigning energy values to gamma-ray pulse-height distributions measured with polyvinyl toluene based detectors. It is based upon the characteristic shape of the spectrum in the region of maximum energy deposition resulting from a single Compton scattering. The validity of this method is first demonstrated by applying it to a set of NaI(Tl) spectra, and comparing those results to the standard photo-peak method of calibrating the same spectra. The method is then applied to a set of polyvinyl toluene derived spectra.

Siciliano, Edward R.; Ely, James H.; Kouzes, Richard T.; Schweppe, John E.; Strachan, Denis M.; Yokuda, Satoru T.

2008-09-01

105

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

NASA Astrophysics Data System (ADS)

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

Dooley, A. W.

1984-03-01

106

Environmental gamma-ray spectra from selected sites in southeastern New Mexico  

SciTech Connect

Environmental gamma-ray spectra were obtained in 1978 and 1979 in the Carlsbad Caverns National Park and in a potash mine operated by the Mississippi Chemical Corporation near Carlsbad, New Mexico, using a high-resolution germanium crystal detector. The spectra are analyzed for components from the uranium decay series, the thorium decay series, cesium-137, and potassium-40. Comparison spectra were obtained at the Avery Island Salt Dome in Louisiana, and from the naturally occurring activity in samples of uranium ore, thorium metal, and sylvite crystals.

Ewing, R.I.

1982-08-01

107

Calculated Neutron and Gamma-Ray Spectra across the Prismatic Very High Temperature Reactor Core  

NASA Astrophysics Data System (ADS)

Neutron and gamma-ray flux spectra are calculated using the MCNP5 computer code and a one-sixth core model of a prismatic Very High Temperature Reactor based on the General Atomics Gas Turbine-Modular Helium Reactor. Spectra are calculated in the five inner reflector graphite block rings, three annular active core fuel rings, three outer graphite reflector block rings, and the core barrel. The neutron spectra are block and fuel pin averages and are calculated as a function of temperature and burnup. Also provided are the total, fast, and thermal radial profile fluxes and core barrel dpa rates.

Sterbentz, James W.

2009-08-01

108

Coincidence summing corrections for positron emitters in germanium gamma spectrometry  

NASA Astrophysics Data System (ADS)

For positron emitters, 511 keV annihilation quanta are in coincidence with other gamma rays in the decay scheme. If the positrons are not localized at the point of decay, annihilation quanta will be produced at a site some distance from the point of emission. The magnitude of the summing coincidence effect will depend upon the position of annihilation. A method for determining the magnitude of the summing effect for a single gamma of energy E in coincidence with the annihilation gammas from non-localized positrons has been developed which makes use of the counting data for the full energy peaks for both the gamma ray (E) and the 511 keV annihilation gammas. With this data and efficiency calibration data one can determine the average total efficiency for the annihilation positions from which 511 keV gammas originate, and thereby obtain the summing correction factor, SCF, for gamma ray (E). Application of the method to a 22Na NIST standard gave excellent agreement of observed emission rates for the 1275 keV gamma with the NIST value for wide ranging degrees of positron localization having summing correction factors ranging from 1.021 to 1.505. The method was also applied successfully to 58Co in neutron-irradiated nickel foils. The method shows promise as a check on the accuracy of the efficiency calibration for a particular detector geometry at the 511 keV energy and energies for other gammas associated with positron emission.

Richardson, A. E.; Sallee, W. W.

1990-12-01

109

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...

110

ANALYSIS OF GAMMA-RAY SCINTILLATION SPECTRA BY THE METHOD OF LEAST SQUARES  

Microsoft Academic Search

The least-squares method is applied to the analysis of gamma ; scintillation spectra, the calculations being performed on a computer. ; Analytical results are obtained rapidly, the accuracy being consistent with the ; calculated precision. The method is particularly suited to routine analysis at ; low counting rates. (auth);

1961-01-01

111

PC based analysis of gamma ray spectra generated by semiconductor detectors  

Microsoft Academic Search

This report describes a spectrum analysis method and computer program for analysis of gamma spectra obtained by using semiconductor detectors and multichannel analyzers. The analysis steps incorporated are: smoothing; peak location using signal processing method of convolution; selectable background subtraction viz linear; polynomial and step like; peak fitting both for singlets and doublets using Mukoyama's method for evaluation of full

M. C. Abani; V. K. Madan

1993-01-01

112

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

113

Programs in C for parameterizing measured 5'' × 5'' NaI gamma response functions and unfolding of continuous gamma spectra  

NASA Astrophysics Data System (ADS)

A 5'' × 5'' NaI(Tl) detector has been used to measure gamma-ray spectra resulting from the decay of aggregate fission products. In order to extract the true gamma-ray energy distribution from the measured spectra, the detector response functions for monoenergetic gamma rays spanning the energy range of the measurements must be determined. At present we have measured 13 such response functions in the energy range 0.081-6.13 MeV. NGRC is a program in C written to implement an interpolation scheme for estimating the response function at any other intermediate energy. This program takes a library of response function tails and constructs a response function matrix which is used as input to a second program CRSUP written for obtaining gamma-ray energy distributions. It assumes the measured spectrum consists of a superposition of a specified number of response functions placed at energies determined by the program according to the detector resolution and spectrum end point energy. The program then computes the distribution of the strength of the response functions in a least-squares fashion. This program is designed to maximize the number of response functions that can be used in modeling the measured spectrum without reducing the number of bins used in each response function. The response functions constructed by the interpolation procedure have been used in the program SPEC-FIT to fit in a least-squares fashion the gamma-ray spectrum of 152 Eu. The fit is an excellent reproduction of both the photopeak and continuous regions of the entire measured spectrum. Finally the validity of the least-square method implemented by CRSUP has also been tested by using this program to unfold an analytically constructed continuous spectrum. The results obtained were in excellent agreement with the assumed distribution function, illustrating the applicability of CRSUP for unfolding other types of continuous spectra as encountered in beta, neutron-time-of-flight and Rutherford-backscattering spectroscopy.

Nguyen, H. V.; Campbell, J. M.; Couchell, G. P.; Li, S.; Pullen, D. J.; Schier, W. A.; Seabury, E. H.; Tipnis, S. V.

1996-02-01

114

On line gamma-ray spectrometry at open sea  

Microsoft Academic Search

Set up and application of a stationary monitoring network for measuring specific ?- activities in the Aegean Sea are described. Three NaI scintillator based spectrometers have been used to detect the gamma rays. The gross counting rate of each system was found to be nearly constant, when there was no rainfall. The volumetric activity of the natural gamma-ray emitter 40K

C. Tsabaris; D. Ballas

2005-01-01

115

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

116

Portable computer to reduce gamma-ray spectra for plutonium isotopic ratios  

SciTech Connect

In response to Task A.63 of the International Safeguards Project Office (ISPO), to upgrade measurement technology used by the International Atomic Energy Agency (IAEA), a portable data-reduction microprocessor was designed and programmed which allows in-field reduction of gamma-ray spectra and interfaces with the IAEA's multichannel analyzers - the 1000 or 2000-channel memory Silena BS27/N. This report describes the components used in assembling the microprocessor unit: hardware, software used to control the unit, and the mathematical formulation used to obtain isotopic ratios from the gamma-ray data. A simple overview is presented of the unit's operation and the results of tests on gamma-ray spectra that sought to verify the unit's operating characteristics and to determine the precision and effectiveness of the software developed for data reduction.

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

1981-05-15

117

Effects of axion-photon mixing on gamma-ray spectra from magnetized astrophysical sources  

SciTech Connect

Astrophysical {gamma}-ray sources come in a variety of sizes and magnetizations. We deduce general conditions under which {gamma}-ray spectra from such sources would be significantly affected by axion-photon mixing. We show that, depending on strength and coherence of the magnetic field, axion couplings down to {approx}(10{sup 13}GeV){sup -1} can give rise to significant axion-photon conversions in the environment of accreting massive black holes. Resonances can occur between the axion mass term and the plasma frequency term as well as between the plasma frequency term and the vacuum Cotton-Mouton shift. Both resonances and nonresonant transitions could induce detectable features or even strong suppressions in finite energy intervals of {gamma}-ray spectra from active galactic nuclei. Such effects can occur at keV to TeV energies for couplings that are currently allowed by all experimental constraints.

Hochmuth, Kathrin A. [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Foehringer Ring 6, 80805 Munich (Germany); Sigl, Guenter [APC - AstroParticules et Cosmologie, 10, rue Alice Domon et Leonie Duquet, 75205 Paris Cedex 13 (France) and Institut d'Astrophysique de Paris, UMR 7095 CNRS-Universite Pierre and Marie Curie, 98 bis boulevard Arago, F-75014 Paris (France)

2007-12-15

118

An MS-DOS-based program for analyzing plutonium gamma-ray spectra  

SciTech Connect

A plutonium gamma-ray analysis system that operates on MS-DOS-based computers has been developed for the International Atomic Energy Agency (IAEA) to perform in-field analysis of plutonium gamma-ray spectra for plutonium isotopics. The program titled IAEAPU consists of three separate applications: a data-transfer application for transferring spectral data from a CICERO multichannel analyzer to a binary data file, a data-analysis application to analyze plutonium gamma-ray spectra, for plutonium isotopic ratios and weight percents of total plutonium, and a data-quality assurance application to check spectral data for proper data-acquisition setup and performance. Volume 3 contains the software listings for these applications.

Ruhter, W.D.; Buckley, W.M.

1989-09-07

119

Isotopic analysis of uranium in U 3O 8 by passive gamma-ray spectrometry  

Microsoft Academic Search

Passive gamma-ray spectrometry was applied to analyze the isotopic composition of uranium in U3O8. Depleted and enriched U3O8 standard reference materials were used to calibrate the system. An independent calibration was performed by standard gamma-ray point sources. U3O8 SRM samples of the 950 series were analyzed. The present results show that the isotopic abundances of 235U in SRMs 950, 950a

Y Nir-El

2000-01-01

120

Coincidence Summing Corrections in Gamma-Ray Spectrometry Using GEANT4 Code  

Microsoft Academic Search

In this paper coincidence summing corrections in gamma-ray spectrometry have been analyzed in depth. Experimental setup included a n-type germanium detector and two efficient geometries of measurement (Marinelli beaker and air filter) calibrated with multi gamma radionuclides in the energy range of 40-1500 keV. Monte Carlo simulations were carried out using the GEANT4 code in order to develop this work.

Santiago Hurtado; Rafael Garcia-Tenorio; Manuel Garcia-Leon

2009-01-01

121

Maintaining Accuracy in Gamma-Ray Spectrometry at High Count Rates  

Microsoft Academic Search

Gamma-ray spectrometry losses through pulse processing dead time and pile-up are best assayed with an external pulse technique. In this work, the virtual pulse generator technique as implemented commercially with the Westphal loss free counting (LFC) module is set up and tested with four high resolution gamma-ray spectrometers. Dual source calibration and decaying source techniques are used in the evaluation

R. Zeisler

2000-01-01

122

Automated construction of detector models for efficiency interpolation in gamma-ray spectrometry  

Microsoft Academic Search

A method was developed for automated construction of detector models in gamma-ray spectrometry, which can be used in Monte Carlo calculations of efficiency calibration curves. Full-energy peak efficiencies were first measured for different gamma-ray energies and for a given sample–detector arrangement and then calculated by the Monte Carlo method. For these calculations a detector model was employed along with a

T. Vidmar; A. Likar

2002-01-01

123

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

124

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

125

On Weak Redshift Dependence of Gamma-Ray Spectra of Distant Blazars  

NASA Astrophysics Data System (ADS)

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

Essey, Warren; Kusenko, Alexander

2012-05-01

126

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

SciTech Connect

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

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

2012-05-20

127

High-pressure xenon detectors for gamma-ray spectrometry  

Microsoft Academic Search

The main results of long-term research on compressed xenon detector properties conducted at the laboratory of cosmic physics of MEPhI are given along with a description of the latest gamma-ray spectrometers based on this work. It is shown that using xenon as working substance, it is possible to create a gamma-ray spectrometer with high energy resolution. The construction and the

V. V. Dmitrenko; V. M. Gratchev; S. E. Ulin; Z. M. Uteshev; K. F. VIasik

2000-01-01

128

ATCA data acquisition system for gamma-ray spectrometry  

Microsoft Academic Search

The gamma-ray spectrometer JET EP2 (Joint European Torus enhancement project 2) project aims to perform high-resolution gamma spectroscopy at very high count rate (up to few MHz). Traditional analogue electronic has count rate and pulse processing limitations (long dead-time, pile-up challenge). Digital pulse processing (DPP) systems have been shown to have better performance than analogue ones for processing neutrons or\\/and

R. C. Pereira; J. Sousa; A. M. Fernandes; F. Patrício; B. Carvalho; A. Neto; C. A. F. Varandas; G. Gorini; M. Tardocchi; D. Gin; A. Shevelev

2008-01-01

129

Study of the. gamma. -ray spectra emitted in formation of the spontaneously fissile isomer ²³⁶U in the (n,. gamma. ) reaction  

Microsoft Academic Search

We have measured the spectra of ..gamma.. rays emitted in formation of the spontaneously fissile isomer ²³⁶U in the (n,..gamma..) reaction. The experiments were carried out in the external beam of thermal neutrons from a reactor. A Ge(Li) detector was used for detection of the ..gamma.. rays and a gas scintillation counter for detection of the fission fragments. The ..gamma..

Y. P. Gangrskii; A. Laitay; B. N. Markov

1976-01-01

130

Deconvolution of gamma-ray spectra obtained with NAI(Tl) detector in a water tank.  

PubMed

Maximum-likelihood fitting by the expectation maximization deconvolution method is presented to analyse gamma-ray spectra recorded using an NaI(Tl) detector for a water monitoring system. The applicability of the method was tested by deconvolving measured spectra taken using an industry standard 3'' x 3'' cylindrical NaI(Tl) detector in a model water tank with several calibration sources. The results show significant removal of the Compton continuum counts and efficient transfer of the counts into the corresponding photo-peaks. The peak-to-total count ratio and the number of counts in the photo-peaks in the deconvolved spectra increased approximately 4.67 and 5.29 times, respectively, compared with those of measured spectra taken using an NaI(Tl) scintillation detector in the case of (137)Cs. PMID:19502359

Rahman, M Sohelur; Cho, Gyuseong; Kang, Bo-Sun

2009-06-05

131

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

132

Rock and soil discrimination by low altitude airborne gamma-ray spectrometry in Payne County, Oklahoma  

Microsoft Academic Search

The ability to identify and discriminate rock and soil types from the ; air using gamma spectrometry was investigated in Payne County, Oklahoma. The ; data, which were reduced to concentration values for K, U, and Th, were obtained ; from a helicopter at an average altitude of 75 feet above the ground. The area ; investigated was underlain by

T. F. Schwarzer; J. A. S. Adams

1973-01-01

133

Measurements of Uranium Enrichment by Four Techniques of gamma-Ray Spectrometry.  

National Technical Information Service (NTIS)

Measurements of uranium enrichment with the uses of the LMRI (France) UO sub 2 standards have been made by four techniques of gamma-ray spectrometry, in order to examine measurement characteristics of each technique. The following results were obtained by...

T. Tojo

1983-01-01

134

Monitoring anthropogenic radioactivity in salt marsh environments through in situ gamma-ray spectrometry  

Microsoft Academic Search

Radionuclide bearing effluents discharged into the Irish Sea have resulted in the accumulation of radionuclides in salt marsh environments which can contribute to critical group exposures. Recent developments in in situ gamma-ray spectrometry provide a novel and effective method for monitoring anthropogenic radionuclide concentrations and distributions within these coastal environments. This paper presents the results from an in situ survey

Andrew N. Tyler

1999-01-01

135

Application of airborne gamma-ray spectrometry to geoscience in China  

Microsoft Academic Search

In this paper, we discuss the theory, method, instrumentation, surveying techniques, and data processing and interpretation in airborne gamma-ray spectrometry and the new development of its applications to geological mapping, gold and nonferrous metallic deposit prospecting, gas and oil exploration, potash deposit prospecting and uranium deposit prospecting in China.

Ye Zhang; Shengqing Xiong; Tianyou Chen

1998-01-01

136

Metrological characterization of the ADONIS system used in gamma-ray spectrometry  

Microsoft Academic Search

In gamma-ray spectrometry, new acquisition systems based on digital signal processing are now commercially available. In order to determine their performance at high count rates, the Commissariat à l’Energie Atomique (CEA), Laboratoire National Henri Becquerel has tested several of these systems. These tests have clearly shown that the performance levels announced by the manufacturers were generally not met. It was

J. Plagnard; J. Morel; A. Tran Tuan

2004-01-01

137

A new technique for processing airborne gamma ray spectrometry data for mapping low level contaminations  

Microsoft Academic Search

A new technique for processing airborne gamma ray spectrometry data has been developed. It is based on the noise adjusted singular value decomposition method introduced by Hovgaard in 1997. The new technique opens for mapping of very low contamination levels. It is tested with data from Latvia where the remaining contamination from the 1986 Chernobyl accident together with fallout from

H. K Aage; U Korsbech; K Bargholz; J Hovgaard

1999-01-01

138

Determination of sulfur in environmental materials by thermal neutron caputre prompt gamma-ray spectrometry  

Microsoft Academic Search

Thermal neutron induced prompt ..gamma..-ray spectrometry has been investigated as a technique to measure elemental S concentrations in complex materials. Comparison of analytical results of standardized materials shows the method to be accurate. Repeated analyses of 100 mg of elemental S gave a 1 percent standard deviation from the mean. The standard deviation increased with decreasing quantities of S. Standardized

Edward T. Jurney; David B. Curtis; Ernest S. Gladney

1977-01-01

139

Effective thickness of bulk samples in “close” measuring gamma-ray spectrometry  

Microsoft Academic Search

Analyzing the experimentally evaluated self-attenuation correction coefficients needed in activity determination by means of gamma-ray spectrometry, the effective thicknesses of bulk samples of three shapes were evaluated. The effective thicknesses deduced significantly differ from the geometrical sample thicknesses in “close” measuring geometry.

T. Boshkova

2003-01-01

140

The development and use of an in situ gamma-ray spectrometry system in North Wales  

Microsoft Academic Search

North Wales has a wide range of levels of natural radioactivity together with significant levels of artificial radionuclides on its coast arising mainly from the Sellafield nuclear processing plant. In situ gamma-ray spectrometry offers a rapid alternative to core sampling for mapping out these radioactivity levels but requires extensive calibration and some knowledge of the depth distribution. Quantitative in situ

J. Macdonald; P. H. Smith; D. J. Assinder

1996-01-01

141

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. 7 figs.

Hartwell, J.K.; Goodwin, S.G.; Johnson, L.O.; Killian, E.W.

1989-02-01

142

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

143

Gamma-ray and neutron leakage spectra calculated for unshieled reactors  

SciTech Connect

The spectra of neutrons and gamma rays escaping from unshielded reactors have been calculated for a number of simplified cases. Such spectra are important in connection with reactors operating in space orbit around the earth, which would normally have little or no heavy shielding. Reactors in space, such as the Soviet RORSAT spacecraft. Knowledge of the characteristics of their leakage spectra may be useful in understanding or minimizing such interference. The Monte Carlo Neutron-Photon (MCNP) code developed at Los Alamos has been used in these calculations. In the cases considered here the critical assembly is assumed to have spherically symmetrical geometry, with a central core of fissionable material surrounded by one or more shells of other material. The outer shells considered include beryllium, beryllium oxide, sodium, potassium, lithium, lithium hydride, and iron. The results obtained, presented as graphs, show that a number of materials that may be used in space reactors should lead to distinctive gamma-ray and neutron leakage spectra. Measurements of such spectra might well be useful in characterizing an unknown reactor type. 16 refs., 33 figs.

Terrell, J.

1990-05-01

144

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

145

Lecture Notes on Computerized gamma-Ray Spectrometry.  

National Technical Information Service (NTIS)

After considering the basic interactions of photons with matter, which can explain the shape of the gamma-ray spectrum, the principles for computer programs for automatic data treatment are considered. The emphasis is on methods for peak search, for deter...

W. L. Zijp

1984-01-01

146

Applications of in Situ gamma-Ray Spectrometry.  

National Technical Information Service (NTIS)

Gamma-ray spectrometric methods using high-resolution Ge(Li) and high purity Ge detectors have been used to quantify the concentrations and external exposure rates of radionuclides in the soil. These in situ methods have been used to study radionuclide de...

R. C. Ragaini J. A. Kirby

1978-01-01

147

Airborne gamma-ray spectrometry in uranium exploration  

Microsoft Academic Search

Uranium exploration is of paramount importance to India to maximize the indigeneous resources to meet the ever increasing demand for energy. Comprehensive regional and local zones of uranium mineralization are needed to be resolved. Such data comprise information on radioactivity in various energy ranges and on lithological knowledge. Airborne gamma-ray spectrometric techniques are particularly suited to provide spatial information. This

S. S. Raghuwanshi

1992-01-01

148

Intercomparison of efficiency transfer software for gamma-ray spectrometry  

Microsoft Academic Search

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

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

2001-01-01

149

Simultaneous Estimation of Pu and Fission Products by Gamma Spectrometry.  

National Technical Information Service (NTIS)

A gamma spectrometric method is described for the simultaneous estimation of Pu and fission products using a 62cc intrinsic germanium detector coupled to a 4K MCA. The 120 KeV peak of /sup 239/Pu was employed for the assay of plutoniu m. The low energy 51...

P. V. Achuthan R. G. Bhogale A. Ramanujam M. R. Iyer D. N. Sharma

1988-01-01

150

Gamma-ray spectrometry analysis of pebble bed reactor fuel using Monte Carlo simulations  

Microsoft Academic Search

Monte Carlo simulations were used to study the gamma-ray spectra of pebble bed reactor fuel at various levels of burnup. A fuel depletion calculation was performed using the ORIGEN2.1 code, which yielded the gamma-ray source term that was introduced into the input of an MCNP4C simulation. The simulation assumed the use of a 100% efficient high-purity coaxial germanium (HPGe) detector,

Jianwei Chen; Ayman I. Hawari; Zhongxiang Zhao; Bingjing Su

2003-01-01

151

On the Shape of Pulse Spectra in Gamma-Ray Bursts  

Microsoft Academic Search

The discovery (by Liang & Kargatis) that the peak energy of time-resolved spectra of gamma-ray burst (GRB) pulses decays exponentially with fluence is analytically shown to imply that the time-integrated photon number spectrum of a pulse should have a unique shape, given by an underlying E^-1 behavior. We also show that the asymptotic low-energy normalization of the time-integrated spectrum is

Felix Ryde; Roland Svensson

1999-01-01

152

Intrinsic spectra and energetics of BeppoSAX Gamma-Ray Bursts with known redshifts  

Microsoft Academic Search

We present the main results of a study of spectral and energetics properties of twelve gamma-ray bursts (GRBs) with redshift estimates. All GRBs in our sample were detected by BeppoSAX in a broad energy range (2-700 keV). From the redshift estimates and the good-quality BeppoSAX time-integrated spectra we deduce the main properties of GRBs in their cosmological rest frames. All

L. Amati; F. Frontera; M. Tavani; J. J. M. in't Zand; A. Antonelli; E. Costa; M. Feroci; C. Guidorzi; J. Heise; N. Masetti; E. Montanari; L. Nicastro; E. Palazzi; E. Pian; L. Piro; P. Soffitta

2002-01-01

153

An Intrinsic Smoothing Mechanism for Gamma-Ray Burst Spectra in the Fireball Model  

Microsoft Academic Search

It is shown here that the differential Doppler shift of different patches of the blast-wave front in the fireball model at varying angles to the line of sight could provide an intrinsic smoothing mechanism for the spectra of gamma-ray bursts (GRBs) and the associated afterglows at lower energy bands. For the model parameters of interest, a blast-wave comoving frame monochromatic

Renyue Cen

1999-01-01

154

Reducing the impact of source brightness fluctuations on spectra obtained by Fourier-transform spectrometry.  

PubMed

We present a method to reduce the impact of source brightness fluctuations (SBFs) on spectra recorded by Fourier-transform spectrometry (FTS). Interferograms are recorded without AC coupling of the detector signal (DC mode). The SBF are determined by low-pass filtering of the DC interferograms, which are then reweighted by the low-pass, smoothed signal. Atmospheric solar absorption interferograms recorded in DC mode have been processed with and without this technique, and we demonstrate its efficacy in producing more consistent retrievals of atmospheric composition. We show that the reweighting algorithm improves retrievals from interferograms subject to both gray and nongray intensity fluctuations, making the algorithm applicable to atmospheric data contaminated by significant amounts of aerosol or cloud cover. PMID:17609726

Keppel-Aleks, Gretchen; Toon, Geoffrey C; Wennberg, Paul O; Deutscher, Nicholas M

2007-07-20

155

Development of a Tool for the Rapid Quantitative Analysis of Multiple Gamma Spectra  

SciTech Connect

Often multiple gamma spectra are acquired for the quantitative measurement of process holdup, filter banks, waste containers, D and D objects, or other such items. These spectra can represent data for single items, background data, and multiple assays of the same item or multiple areas representative of a single process area. The spectra are often collected under differing circumstances with regard to attenuating materials, distances, assay times, relative backgrounds, and many other such parameters. Quantitative results, and associated errors, are often dependent on multiple calibration constants, assays of varying isotopes, source geometries (point, line, or area), background averaging, Compton effects, and the accurate analysis, i.e. region of interest, of the raw gamma spectra. A tool has been developed to assist in this endeavor. The calculations have been quality checked so that the tool can readily be used with assurance that the calculations are consistent and correct. This tool allows for multiple spectra (up to 150) to be compared and manipulated. The tool has features for: dynamic average background subtraction; accounting for varying Compton effects; different calibration constants; up to three attenuating materials; any gamma energy; and variance in collection parameters such as distance, angle, assay times, and isotope. Selections of point, line, or area calculations are easily specified. The tool has a report writer that allows for averaging over multiple assays, graphing of activity (e.g., graphing activity in a sump allows the hot spots to be identified), and presentation of results with associated error components or MLDs. The resulting database allows for easy self-documentation and archiving.

HODGE, CHRISTOPHERA.

2004-06-28

156

NEUTRON GENERATOR OUTPUT MONITORING FOR NORMALIZATION OF GAMMA-RAY SPECTRA.  

SciTech Connect

Neutron generators (NG) being devices where neutron outputs are accomplished electrically, suffer from fluctuations in their outputs. Of particular importance are the short term variations that may affect individual data acquisition runs. Thus when using NGs for quantitative neutron-induced gamma-ray spectroscopy, the neutron output must be continuously monitored in real time, and normalization procedures subsequently applied to properly evaluate the gamma-ray spectra. Using a plastic scintillator, we developed a scheme for detecting fast neutrons that relies firstly, on recording a spectrum and, secondly, on establishing a region-of-interest (ROI) that may effectively discriminate against gamma rays that are always present in a neutron field. We discuss the optimization of these procedures for a field system to measure carbon in soil.

MITRA,S.; WIELOPOLSKI, L.

2006-05-08

157

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

158

Basic characterization of highly enriched uranium by gamma spectrometry  

Microsoft Academic Search

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

Cong Tam Nguyen; József Zsigrai

2006-01-01

159

Basic characterization of highly enriched uranium by gamma spectrometry  

Microsoft Academic Search

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

Cong Tam Nguyen; Jozsef Zsigrai

2005-01-01

160

Monitoring of Martian atmosphere with gamma-ray spectrometry  

NASA Astrophysics Data System (ADS)

Mars Odyssey has been monitoring the leakage gamma-rays from Mars since 2002 [1]. The spectrum of these gamma-rays is made of a dominating continuum plus lines (only 4% of the count rates) [2]. The latter have been used to build compositional maps of the surface [3]; the former can be analyzed to monitor atmospheric variations with time and place [4, 5]. Sometimes both aspects can be combined when during polar winters it is possible to track the argon in the atmosphere through its discrete gamma-ray line [6]. The Martian atmosphere is quite transparent (free mean path of about 100km) at these energies (100 keV - 10 MeV), and consequently the continuum varies by only a few percents over the Martian year. However the statistics are good enough to see these variations. Previous studies revealed short and long term time variations, as well as regional differences. In particular we noticed earlier that the atmospheric cycle looks slightly different from one year to the other. Deep basins (Argyre and Hellas) seem also to act as reservoirs at some seasons. We will present an update of the study of the gamma-ray continuum, including the latest data available, in terms of transparency of the Martian atmosphere. [1] Boynton et al. (2004) Space Sci. Rev., 110 (1), 37-83; [2] Evans et al. (2006) J. Geophys. Res., accepted; [3] Boynton et al. (2006) J. Geophys. Res., in preparation; [4] Gasnault et al. (2003) LPSC 34, abstract #1649 CD-ROM; [5] Gasnault et al. (2005) 1st Mars Express Sci. Conf., Noordwijk, Netherlands; [6] Sprague et al. (2006) J. Geophys. Res., accepted.

Gasnault, O.; D'Uston, C.; Forni, O.; Maurice, S.

161

Deconvolution of Mixture Spectra from Ion-Trap Data-Independent-Acquisition Tandem Mass Spectrometry  

PubMed Central

Data-independent tandem mass spectrometry isolates and fragments all of the molecular species within a given mass-to-charge window, regardless of whether a precursor ion was detected within the window. For shotgun proteomics on complex protein mixtures, data-independent MS/MS offers certain advantages over the traditional data-dependent MS/MS: identification of low-abundance peptides with insignificant precursor peaks; more direct relative quantification, free of biases caused by competing precursors and dynamic exclusion; and faster throughput due to simultaneous fragmentation of multiple peptides. However, data-independent MS/MS, especially on low-resolution ion-trap instruments, strains standard peptide identification programs, because of less precise knowledge of the peptide precursor mass and large numbers of spectra composed of two or more peptides. Here we describe a computer program called DeMux that deconvolves mixture spectra and improves the peptide identification rate by ~25%. We compare the number of identifications made by data-independent and data-dependent MS/MS at the peptide and protein levels: conventional data-dependent MS/MS makes a greater number of identifications but is less reproducible from run to run.

Bern, Marshall; Finney, Gregory; Hoopmann, Michael R.; Merrihew, Gennifer; Toth, Michael J.; MacCoss, Michael J.

2010-01-01

162

Utilization of Concurrently Gathered Pulser Data for Complete Spectral Validation of gamma-Ray Spectra from Germanium Detectors.  

National Technical Information Service (NTIS)

Some of the capabilities and limitations of using concurrently gathered pulser data for energy calibration, dead time correction, and pile-up loss correction of gamma ray spectra from germanium detectors have been investigated. This report deals with the ...

L. O. Johnson E. W. Killian R. G. Helmer R. A. Coates

1980-01-01

163

Natural Radiation from Soil using Gamma-Ray Spectrometry  

SciTech Connect

We have studied the distribution of natural radioactivity in the soil of Interlagos, in Sao Paulo city and Billings Reservoir, in Sao Bernardo do Campo, Sao Paulo, Brazil. The main contribution of the effective radiation dose is due to the elements of the {sup 238}Th decay series, with smaller contributions from {sup 40}K and the elements of the series of {sup 238}U. The results indicate the dose in all of the studied areas is around the average international dose due to external exposure to gamma rays (0.48 mSv/yr) proceeding from natural terrestrial elements.

Silveira, M. A. G.; Moreira, R. H.; Paula, A. L. C. de [Centro Universitario da FEI, Sao Bernardo do Campo, Sao Paulo (Brazil); Medina, N. H. [Instituto de Fisica da Universidade de Sao Paulo, Sao Paulo (Brazil)

2009-06-03

164

Detection of Anomalous Gamma-Ray Spectra for On-Site Inspection  

SciTech Connect

This work aims to solve some of the technical and logistical challenges inherent in performing On Site Inspection activities under the authority of the Comprehensive Nuclear-Test-Ban Treaty. Inspectors require equipment that can reliably identify the radionuclide signatures of nuclear test explosions amid a background of environmental contamination. Detection of these radiation anomalies by mobile search teams in the air or on the ground can narrow the search field and target specific areas for more detailed inspection or sampling. The need to protect confidential information of the inspected State Party, especially regarding past nuclear testing activities, suggests that full access to measured gamma-ray spectra should be limited. Spectral blinding techniques---in which only a fraction of the information derived from the spectra is displayed and stored---have the potential to meet the needs of both the OSI team and the State Party. In this paper, we describe one such algorithm that we have developed for identifying anomalous spectra from handheld, mobile, or aerial sensors. The algorithm avoids potential sensitivities by reducing the gamma-ray spectrum into a single number that is displayed and stored. A high value indicates that the spectrum is anomalous. The proposed technique does not rely on identifying specific radionuclides, operates well in the presence of high background variability, and can be configured to ignore specific spectral components. In previous work, the algorithm has proven very effective in classifying gamma-ray spectra as anomalous or not, even with poor statistical information. We performed a limited simulation of an airborne search scenario to demonstrate the potential algorithm for OSI missions. The technique successfully detected an injected source of interest whose count rate was an order of magnitude below background levels. We also configured the algorithm to ignore 137Cs as irrelevant to the mission. The resulting alarm metrics were unaffected by the presence of injected 137Cs contamination.

Seifert, Carolyn E.; Myjak, Mitchell J.; Pfund, David M.

2009-05-29

165

Gamma ray spectrometry of LDEF samples at SRL  

NASA Astrophysics Data System (ADS)

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 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 have been reported to collect noticeable Be-7 on their leading surfaces. No significant Be-7 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 percent 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.

1991-07-01

166

Determination of plutonium mass using gamma-ray spectrometry  

NASA Astrophysics Data System (ADS)

Plutonium sources with well-known isotopic ratios are routinely used in the calibration and testing of radioactive waste assay systems. The laboratories that supply these isotopic standards often do not quantify the plutonium mass. Knowledge of total plutonium mass in the sources is important for verifying the performance of passive neutron counters. The independent determination of total plutonium mass by gamma-ray techniques is rendered difficult by the lack of adequate information regarding the sample matrix and containment of the sources. Therefore, a technique that did not require knowledge of the sample matrix or containment was used to determine the plutonium masses. The technique was based on empirically extrapolating the apparent mass as a function of photon energy to conditions approximating zero photon attenuation. It was tested using measurements performed with three certified reference materials supplied by the New Brunswick Laboratory (NBL). Results were compared to those obtained from a high-efficiency neutron counter calibrated using 252Cf. The weighted average of the ratio of gamma ray to HENC plutonium masses was determined to be 0.942+/-0.029.

Venkataraman, Ramkumar; Croft, Stephen

2003-06-01

167

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

168

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

169

Low-level gamma-ray spectrometry for analysing fusion plasma conditions  

NASA Astrophysics Data System (ADS)

A new method, combining activation by neutrons and charged particles with ultra low-level gamma-ray spectrometry, aimed at obtaining a better understanding and more adequate measurements of MeV particle leaks in magnetic fusion devices was studied here. A total of 36 samples containing Ti, LiF, B4C and W were placed in a boron-nitride holder mounted on the ceiling of the JET Tokamak. The samples were activated by 63 pulses from a D 3He plasma and were later measured using underground gamma-ray spectrometry. The radionuclides 7Be, 46Sc, 54Mn, 56Co, 57Co, 58Co, 124Sb, 181Hf, 182Ta, 181W and 185W were detected in several of the samples, with very low levels of activity of 47Sc and 48V found in a few of the samples. The various production channels for the radionuclides in question are discussed.

Wieslander, J. S. Elisabeth; Hult, Mikael; Bonheure, Georges; Arnold, Dirk; Dombrowski, Harald; Gasparro, Joël; Laubenstein, Matthias; Marissens, Gerd; Vermaercke, Peter

2008-06-01

170

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

SciTech Connect

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 require accurate knowledge of gamma energies and absolute quantum intensities. For some spectral lines, there are no reported measurements of absolute quantum intensities and in some cases where reports are available the measured intensities are not in agreement. In order to improve this data base, the spectra of gamma rays (of nuclides in the uranium and actinium series) with energies between 40 and 1400 keV were measured using high-resolution germanium detectors. A brief description of the spectroscopy system, computational algorithms for deconvolution, and methods of calibration for energy and efficiency, are described. The measured energies and absolute quantum intensities are compared with those reported in the literature.

Momeni, M.H.

1981-01-01

171

An intercomparison of Monte Carlo codes used in gamma-ray spectrometry  

Microsoft Academic Search

In an intercomparison exercise, the Monte Carlo codes most commonly used in gamma-ray spectrometry today were compared with each other in order to gauge the differences between them in terms of typical applications. No reference was made to experimental data; instead, the aim was to confront the codes with each other, as they were applied to the calculation of full-energy-peak

T. Vidmar; I. Aubineau-Laniece; M. J. Anagnostakis; D. Arnold; R. Brettner-Messler; D. Budjas; M. Capogni; M. S. Dias; L. E. De Geer; A. Fazio; J. Gasparro; M. Hult; S. Hurtado; M. Jurado Vargas; M. Laubenstein; K. B. Lee; Y. K. Lee; M. C. Lepy; F. J. Maringer; V. Medina Peyres; M. Mille; M. Moralles; S. Nour; R. Plenteda; M. P. Rubio Montero; O. Sima; C. Tomei; G. Vidmar

2008-01-01

172

The potential of gamma-ray spectrometry as supplementary information for mapping central European soils  

NASA Astrophysics Data System (ADS)

Permanently updated soil maps are needed inter alia for the prediction of landslide hazards, flooding and drought effects, land degradation monitoring, and precision farming. Since comprehensive and intensive field mapping is not affordable, alternative mapping approaches are required. A promising tool, with quite unrecognised potential for modern soil science is gamma-ray spectrometry. As the radioelements potassium, thorium and uranium respond differently to soil forming processes, it should be possible to infer from their concentration on weathering status, and after calibration on soil properties and types. This paper aims to investigate the potential of airborne gamma spectrometry for mapping of central European soils and soil properties. The study was conducted for a test site in Southern Saxony, Germany, 140*85 km wide, representing diverse soil landscapes. Seven different petrographic training and validation areas were chosen each. To assess the potential of gamma-ray spectrometry as additional data layer, predictions were carried out (i) with and (ii) without radiometric data. The outputs were compared with independent soil information of the validation areas. Both prediction runs used the following predictors: elevation, slope, curvature, planform curvature, profile curvature, terrain ruggedness index, relative altitude, vertical distance above drainage network, wetness index, and convergence index. As additional predictor parent material derived from a reclassification of the official geological map (1:1M scale) was used. As radiometric properties potassium, thorium and uranium were used. The radiometric raster datasets were generated by universal kriging using relative altitude as covariate. Training and validation datasets were selected from a comprehensive dataset representing more than 14.000 point data. Point data include soil types and substrates, and for more than 800 sites soil profiles with analysed texture, pH, exchangeable cations, nutrients, and efficient cation exchange capacity. The study shows that gamma spectrometry is suitable to enhance the prediction of soil types and properties such as texture significantly.

Schuler, U.; Bock, M.; Baritz, R.; Willer, J.; Pickert, E.; Kardel, K.; Herrmann, L.

2012-04-01

173

Measurement of plutonium and uranium isotopic abundances by gamma-ray spectrometry  

SciTech Connect

The isotopic composition of plutonium and uranium is needed for purposes of sample confirmation, or for interpreting results from calorimeters or neutron-coincidence measurement instruments to determine nuclear material mass. The authors have developed measurement methods and computer codes utilizing high-resolution gamma-ray spectrometry to measure the relative isotopic abundances of plutonium and uranium in various forms nondestructively. The computer codes, known as MGA and MGAU, have unique analysis methodologies that the authors briefly describe in this paper.

Ruhter, W.D. [Lawrence Livermore National Lab., CA (United States); Gunnink, R. [Gunnink (Ray), Fremont, CA (United States)

1996-02-01

174

Natural radioactivity traces in South-Brazilian cereal flours by gamma-ray spectrometry  

Microsoft Academic Search

Summary  Cereal flours are the major component of the Brazilian diet and are also important exportation products. Radioactivity concentrations\\u000a of 232 Th, 226Ra, 40K and 137Cs were determined in commercial samples of South-Brazilian cereal flours (soy, wheat, corn, manioc, rye and oat flour) to\\u000a verify the radiological security of these foodstuffs. The measurements were carried out by gamma-ray spectrometry using a

V. Scheibel; C. R. Appoloni; H. Schechter

2006-01-01

175

On the invariability of the total-to-peak ratio in gamma-ray spectrometry  

Microsoft Academic Search

It is demonstrated that the assumption on the independence of the total-to-peak ratio of the source position in gamma-ray spectrometry holds for coaxial detectors with sufficient accuracy to make it applicable to the determination of the full energy peak efficiencies in environmental measurements via the so-called efficiency transfer method. The calculations show that for planar detectors the assumption breaks down

Tim Vidmar; Andrej Likar

2004-01-01

176

Low-level gamma-ray spectrometry using Ge-detectors  

Microsoft Academic Search

The technological advances that have taken place during the past 45 years in the fabrication of high purity germanium crystals have had a significant impact on low-level gamma-ray spectrometry. Today, Ge-detectors with high purity Ge-crystals of 2 kg are readily available and detectors with crystals up to 5 kg can be produced. Use of large area crystals results in high

Mikael Hult

2007-01-01

177

The determination of minor elements in steel by proton-induced prompt gamma-ray spectrometry  

Microsoft Academic Search

Pure elemental targets of Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo and W were irradiated with protons from 3.5 to 6.0 MeV,\\u000a interference-free sensitivities were calculated for analysis by prompt gamma-ray spectrometry and sensitivity curves were\\u000a plotted to show the variation of sensitivity with bombarding energy. Appropriate bombarding energies were selected for analysis\\u000a and the extent

M. Peisach; D. Gihwala

1981-01-01

178

Calculation of “LS-curves” for coincidence summing corrections in gamma ray spectrometry  

Microsoft Academic Search

When coincidence summing correction factors for extended samples are calculated in gamma-ray spectrometry from full-energy-peak and total efficiencies, their variation over the sample volume needs to be considered. In other words, the correction factors cannot be computed as if the sample were a point source. A method developed by Blaauw and Gelsema takes the variation of the efficiencies over the

Tim Vidmar; Matjaz Korun

2006-01-01

179

Low-level gamma-ray spectrometry for analysing fusion plasma conditions  

Microsoft Academic Search

A new method, combining activation by neutrons and charged particles with ultra low-level gamma-ray spectrometry, aimed at obtaining a better understanding and more adequate measurements of MeV particle leaks in magnetic fusion devices was studied here. A total of 36 samples containing Ti, LiF, B4C and W were placed in a boron-nitride holder mounted on the ceiling of the JET

J. S. Elisabeth Wieslander; Mikael Hult; Georges Bonheure; Dirk Arnold; Harald Dombrowski; Joël Gasparro; Matthias Laubenstein; Gerd Marissens; Peter Vermaercke

2008-01-01

180

Determination of metals in alloys by neutron capture gamma-ray spectrometry  

Microsoft Academic Search

A collimated neutron beam capable of providing a thermal neutron flux of 4.75·107 n·cm?2·sec?1 has been used to analyze alloy samples of 1–5 g during relatively short irradiation times of 30 min by the use of neutron\\u000a capture gamma-ray spectrometry. The analyses were performed by using a mathematical treatment that relates the count ratio\\u000a of every constituent present in the

M. Heurtebise; J. A. Lubkowitz

1976-01-01

181

Artificial neural network modelling of uncertainty in gamma-ray spectrometry  

Microsoft Academic Search

An artificial neural network (ANN) model for the prediction of measuring uncertainties in gamma-ray spectrometry was developed and optimized. A three-layer feed-forward ANN with back-propagation learning algorithm was used to model uncertainties of measurement of activity levels of eight radionuclides (226Ra, 238U, 235U, 40K, 232Th, 134Cs, 137Cs and 7Be) in soil samples as a function of measurement time. It was

S. Dragovic; A. Onjia; S. Stankovic; I. Ani?in; G. Bacic

2005-01-01

182

An analysis of the potassium concentrations of soft drinks by HPGe gamma spectrometry  

Microsoft Academic Search

Potassium, in a variety of compounds, occurs in abundance in the Earth’s crust, and is an essential nutrient for human health.\\u000a A naturally occurring radioactive isotope of potassium, 40K, is found in the food and water that we consume. This paper presents the results of a gamma spectrometry analysis of the\\u000a 40K concentrations of a selection of commercial soft drinks.

Guillermo Espinosa; Ilsa Hernández-Ibinarriaga; Jose-Ignacio Golzarri

2009-01-01

183

Gamma Ray Spectrometry of Well Cores for Identification of Lithologies of Pacific Margin Basins of India  

Microsoft Academic Search

Natural Gamma Ray Spectrometry for determining the radioactive concentrations of potassium (40K), uranium (238U), and thorium (232Th) of well cores from the exploratory wells of Pacific margin basins were carried out in the laboratory. The measurements\\u000a were performed using a HP-Ge detector and an electronic setup coupled to a PC-based data acquisition and analysis system.\\u000a Data analyses of 68 samples

Hima Bindu Pitta; A. S. Nageswara Rao

2011-01-01

184

An axially symmetric gamma-ray backscatter system for DuMond spectrometry  

Microsoft Academic Search

An axially symmetric spectrometer is described which evolved from a program of measuring Compton profiles with unusually high geometric efficiency. When fitted with a large-volume Ge detector for combined X-ray and gamma-ray spectrometry, such as the 51 mm diameter LO-AX detector from EG&G, it allows Compton profiles to be measured at counting rates in excess of 20000 cps. The axially

Innes K. MacKenzie

1990-01-01

185

Large Goldanskii effect in quadrupole Mossbauer spectra of the 103.2 keV gamma ray of 153Eu  

Microsoft Academic Search

A large Goldanskii effect was observed in the recoilless absorption spectra of the 103.2 keV gamma ray of 153Eu in Eu2Ti2O7. Values for the quadrupole interaction parameters, the crystal field parameter V02 keV gamma ray of 153Eu and the shielding parameter sigma2 were deduced.

H. Armon; E. R. Bauminger; A. Diamant; I. Nowik; S. Ofer

1973-01-01

186

MS-DOS-based program for analyzing plutonium gamma-ray spectra. Volume 1. Data-analysis methodology and software.  

National Technical Information Service (NTIS)

A plutonium gamma-ray analysis system that operates on MS-DOS-based computers has been developed for the International Atomic Energy Agency (IAEA) to perform in-field analysis of plutonium gamma-ray spectra for plutonium isotopics. The user interacts with...

W. D. Ruhter W. M. Buckley

1989-01-01

187

Problem of Dead Layer in gamma Ray Burst Spectra Recorded with NaI or Csi Crystals.  

National Technical Information Service (NTIS)

A Monte Carlo program is used for simulating a dead layer on NaI crystals and to calculate the resultant count spectra in different cases. A study of the dead layer effect is presented. Applications to some observed gamma-ray burst spectra are performed. ...

E. Jourdain M. Niel J. P. Roques

1989-01-01

188

The imprint of the extragalactic background light in the gamma-ray spectra of blazars.  

PubMed

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. PMID:23118013

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

189

Low-background gamma spectrometry for environmental radioactivity.  

PubMed

Development and performance of a low-background gamma-ray spectrometer are described. The spectrometer consists of a 131% efficient Ge detector in U-type configuration. The passive shielding consists of ultrapure lead of 6" thickness. A top muon guard is used as an active shielding. The spectrometer and shielding are positioned inside a steel room made of 6"-thick pre-World War II iron. The steel room is located underground with 33 m of water-equivalent overburden. The total integrated background rate in the energy range 50-2,700 keV was measured at 0.068 counts per second per 100 cm3 Ge volume. The spectrometer serves as a reference instrument for low-level and highly accurate environmental radioactivity measurements. One specific application of 228Ra determination in drinking water is described. With a 1 l water sample, 1-step chemical procedure, and 1,000 min counting time, a detection limit Ld = 20 mBq/l (0.55 pCi/l) was reached, which meets the EPA mandated limit of 1 pCi/l. Methods of upgrading the spectrometer as well as the predicted improvements in 228Ra detection, including direct counting of water without chemical processing, are discussed. PMID:12150281

Semkow, T M; Parekh, P P; Schwenker, C D; Khan, A J; Bari, A; Colaresi, J F; Tench, O K; David, G; Guryn, W

2002-08-01

190

Hyperfine splitting of EPR spectra of paramagnetic centers created by gamma irradiation of cesium trihydrogen selenite  

SciTech Connect

The EPR spectra of gamma irradiated cesium trihydrogen selenite at 25/sup 0/C were analyzed to determine g and hyperfine tensor principal values and direction cosines. The observed spectra were from a single type of center with g/sub 11/, g/sub 22/, and g/sub 33/ equal to 1.995, 2.031, and 2.007 (+- 0.002), respectively. Hyperfine splitting from /sup 133/Cs and from /sup 77/Se was observed with A/sub 11/, A/sub 22/, A/sub 33/ values of 11.9, -7.7, -7.2 G and 263, +- 85, +- 100 G, respectively. The principal axes of g and the /sup 77/Se hyperfine tensor are nearly aligned with the special directions of one face of one of the SeO/sub 3/ pyramids, indicating that the center is an SeO/sup -//sub 2/ radical.

Gade, S.; Johnson, B.; Halvorsen, A.; Knispel, R.

1981-03-01

191

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

SciTech Connect

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

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

2009-06-15

192

Anomalies in low-energy gamma-ray burst spectra with the Fermi Gamma-ray Burst Monitor  

NASA Astrophysics Data System (ADS)

Context. A Band function has become the standard spectral function used to describe the prompt emission spectra of gamma-ray bursts (GRBs). However, deviations from this function have previously been observed in GRBs detected by BATSE and in individual GRBs from the Fermi era. Aims: We present a systematic and rigorous search for spectral deviations from a Band function at low energies in a sample of the first two years of high fluence, long bursts detected by the Fermi Gamma-ray Burst Monitor (GBM). The sample contains 45 bursts with a fluence greater than 2 × 10-5 erg/cm2 (10-1000 keV). Methods: An extrapolated fit method is used to search for low-energy spectral anomalies, whereby a Band function is fit above a variable low-energy threshold and then the best fit function is extrapolated to lower energy data. Deviations are quantified by examining residuals derived from the extrapolated function and the data and their significance is determined via comprehensive simulations which account for the instrument response. This method was employed for both time-integrated burst spectra and time-resolved bins defined by a signal-to-noise ratio of 25? and 50?. Results: Significant deviations are evident in 3 bursts (GRB 081215A, GRB 090424 and GRB 090902B) in the time-integrated sample (~7%) and 5 bursts (GRB 090323, GRB 090424, GRB 090820, GRB 090902B and GRB 090926A) in the time-resolved sample (~11%). Conclusions: The advantage of the systematic, blind search analysis is that it can demonstrate the requirement for an additional spectral component without any prior knowledge of the nature of that extra component. Deviations are found in a large fraction of high fluence GRBs; fainter GRBs may not have sufficient statistics for deviations to be found using this method.

Tierney, D.; McBreen, S.; Preece, R. D.; Fitzpatrick, G.; Foley, S.; Guiriec, S.; Bissaldi, E.; Briggs, M. S.; Burgess, J. M.; Connaughton, V.; Goldstein, A.; Greiner, J.; Gruber, D.; Kouveliotou, C.; McGlynn, S.; Paciesas, W. S.; Pelassa, V.; von Kienlin, A.

2013-02-01

193

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

194

Speciation Gamma-Spectrometry: the Fate of Environmental Radio-Nuclides in Hard-Water Lakes  

NASA Astrophysics Data System (ADS)

A sequential fractionation method for simultaneous and absolute measurement of environmental radio-nuclides, 241Am, 210Pb, 226Ra, 137Cs, 40K and 234Th/238U, by gamma-spectrometry was tested and applied to hard-water lake-sediments. The carbonate, fulvic, humic and mineral insoluble fractions were extracted from the sediments. Correction of self-absorption and geometrical effects, arising from the conditioning of bulk and fractionated sediments, were done using Monte Carlo simulations. This "non-destructive" fractionation procedure allows further analysis of other chemical species in the same fractions thus creating possibilities to study the dynamics of self-cleaning mechanism in lakes. The results demonstrate that the procedure is quantitative and suitable for the determination of environmental key radio-tracers in different fractions. Unlike other fresh-water sediments the major part of the environmental radio-nuclides is associated with "mineral" fractions. This speciation gamma-spectrometry procedure was supplemented by isotope-dilution alpha-spectrometry 210Po (210Pb), for determining the acid-soluble organic fractions in fresh-water lakes. The overall speciation procedure demonstrated that carbonate fractions, extracted from hard-water lake sediments, could be separated either free from, or associated with, fulvic-compounds. This speciation procedure can be applied to other aquatic deposits, however supplementary steps can be added if other data are required.

El-Daoushy, F.; Liger, E.; Hernández, F.; Casper, P.

2005-01-01

195

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

196

Measurements of gamma radiation levels and spectra in the San Francisco Bay Area  

NASA Astrophysics Data System (ADS)

Much of the radiation received by an average person is emitted by naturally-occurring radioactive isotopes from the thorium, actinium, and uranium decay series, or potassium. In this study, we have measured gamma radiation levels at various locations in the San Francisco Bay Area and the UC Berkeley campus from spectra taken using an ORTEC NOMAD portable data acquisition system and a large-volume coaxial HPGe detector. We have identified a large number of gamma rays originating from natural sources. The most noticeable isotopes are ^214Bi, ^40K, and ^208Tl. We have observed variations in counting rates by factors of two to five between different locations due to differences in local conditions -- such as building, concrete, grass, and soil compositions. In addition, in a number of outdoor locations, we have observed 604-, 662-, and 795-keV gamma rays from ^134,137Cs, which we attribute to fallout from the recent Fukushima reactor accident. The implications of these results will be discussed.

Lo, B. T.; Brozek, K. P.; Angell, C. T.; Norman, E. B.

2011-10-01

197

An algorithm for intrinsic gain and offset stabilization of gamma-ray pulse height spectra  

SciTech Connect

In this paper, the authors describe a new algorithm for the intrinsic stabilization of the pulse height spectra (PHS) of multiply scattered [gamma] rays, which does not rely on the use of radioactive check sources, but makes gain and offset corrections based on spectral shape. In the authors' implementation, the input spectrum is transformed (interpolated) form assumed (trial) values of gain and offset to a set of standard values, the PHS are projected onto four spectral principal components, and the mean square error between the transformed input spectrum and its rank four representation is minimized. For noise-free spectra, the authors find that the algorithm can estimate gain with an r.m.s. error of 1%, and offset with an r.m.s. error of 0.6 keV when the spectral components are determined form the test data. For noisy spectra the r.m.s. errors for gain and offset are 4% and 1.7 keV respectively.

Lu, J. (Bull Worldwide Information System, Billerica, MA (United States)); Watson, C.C. (Schlumberger-Doll Research Center, Ridgefield, CT (United States))

1992-10-01

198

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

199

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

SciTech Connect

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

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

2007-08-01

200

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

201

A combined gamma-alpha method of determining plutonium isotope compositions  

Microsoft Academic Search

A combined method is used for determining the isotopic composition of plutonium made in a power station reactor, which uses gamma and alpha spectrometry. The scope for gamma spectrometry was determined from the gamma spectra of eight plutonium specimens having isotope compositions similar to that of spent VVER fuel. When the data from all the series were used, the plutonium

V. V. Berdikov; M. A. Suvorov

1986-01-01

202

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

2010-01-27

203

Coincidence-summing corrections for extended sources in gamma-ray spectrometry using Monte Carlo simulation  

NASA Astrophysics Data System (ADS)

A new approach for the correction of summing effects in gamma-ray spectrometry with volume sources is proposed. Using a Monte Carlo code and a formalism to describe the decay schemes, the apparent full-energy-peak efficiency (which would be obtained by neglecting the summing effects) is calculated at the same time as the true one; the ratio of these two values is the correction factor. It is demonstrated that, by means of simulation, efficiencies can be evaluated with a suitable accuracy.

Décombaz, Marc; Gostely, Jean-Jacques; Laedermann, Jean-Pascal

1992-02-01

204

Measurements of activation induced by environmental neutrons using ultra low-level gamma-ray spectrometry.  

PubMed

The flux of environmental neutrons is being studied by activation of metal discs of selected elements. Near the earth's surface the total neutron flux is in the order of 10(-2) cm(-2)s(-1), which gives induced activities of a few mBq in the discs. Initial results from this technique, involving activation at ground level for several materials (W, Au, Ta, In, Re, Sm, Dy and Mn) and ultra low-level gamma-ray spectrometry in an underground laboratory located at 500 m.w.e., are presented. Diffusion of environmental neutrons in water is also measured by activation of gold at different depths. PMID:10724430

Martínez Canet, M J; Hult, M; Köhler, M; Johnston, P N

2000-03-01

205

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

206

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

207

Coincidence summing corrections for the natural decay series in gamma-ray spectrometry.  

PubMed

Using a Monte Carlo code and a Markov formalism to describe the decay schemes, coincidence-summing correction factors can be calculated with a suitable accuracy. For two different measuring geometries and an HPGe detector, calculated and experimental correction factors have been shown to closely agree for 152Eu. The simulation method has subsequently been applied in assessing the need for coincidence-summing corrections for members of the uranium, thorium and actinium series measurable by gamma-spectrometry. Correction factors were calculated for predominant gamma emissions significantly affected by coincidence-summing effects and the correctness of our calculations tested for environmental samples. The test makes it evident that in order to obtain reliable and unbiased activity values for some natural radionuclides coincidence summing cannot be neglected in environmental measurements at small source-detector distances. PMID:11258526

García-Talaver, M; Laedermann, J P; Décombaz, M; Daza, M J; Quintana, B

2001-05-01

208

The nonthermal pair model for the X-ray and gamma-ray spectra from active galactic nuclei  

Microsoft Academic Search

The nonthermal pair model for the X- and gamma-ray spectra from Seyfert 1 type galaxies disagreed with the few data available at the introduction of the model 1983-1985. Presently, this few-parameter model (with a few enhancements) is the only model that (1) includes most of the relevant microphysics, (2) that can explain most of the general features of the EUV-gamma-ray

Roland Svensson

1994-01-01

209

EFFECT OF $gamma$RADIATION ON THE SHAPE OF MOSSBAUER RESONANCE ABSORPTION SPECTRA IN TIN-ORGANIC COMPOUNDS  

Microsoft Academic Search

The effect of gamma radiation on the shape of the spectra of Mossbauer ; resonance absorption of 23.8-kev gamma quanta in tin-organic compounds is ; investigated. The change in the spectrum for the compound (CâHâ)\\/sub ; 2\\/ SnSOâ corresponds to splitting of the compound and formation of the ; compounds SnSOâ and possibly (CâHâ)â SnSOâ (upon ; irra diation in

A. Yu. Aleksandrov; N. N. Delyagin; K. P. Mitrofanov; L. S. Polak; V. S. Shpinel

1962-01-01

210

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

SciTech Connect

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

Winn, W.G.

1999-07-28

211

On the X-Ray Spectra of Anomalous X-Ray Pulsars and Soft Gamma Repeaters  

NASA Astrophysics Data System (ADS)

We revisit the apparent correlation between soft X-ray band photon index and spin-down rate \\dot{?} previously reported for Anomalous X-ray Pulsars (AXPs) and Soft Gamma Repeaters (SGRs) by Marsden & 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 \\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 \\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 ~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.

2010-02-01

212

Modeling of Gamma-ray Spectra to Direct Efficient Chemical Separations  

SciTech Connect

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

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

2008-06-15

213

Assessment of calibration parameters for an aerial gamma spectrometry system using Monte-Carlo technique.  

PubMed

During a radiation emergency subsequent to a nuclear accident or weapon fallout, quick assessment of the ground contamination and the resulting exposure is of prime importance in planning and execution of effective counter measures. For an online assessment of ground contamination, it is essential to calibrate the detector system for several parameters viz. the source energy, source deployment matrix, the flight altitude and position above the contaminated surface. This article discusses the methodology to predict all the necessary parameters like photon fluence at various altitudes, the photo-peak counts in different energy windows, Air to Ground Correlation Factors IAGCF) and the dose rate at any height due to air scattered gamma ray photons. The methodology includes generation of theoretically simulated gamma spectra at a required detector position for a given source distribution on the ground using Monte-Carlo method provided by general purpose coupled neutron/photon transport code (MCNP CCC-200). Thus generated gamma spectra are analyzed to arrive at the required parameters mentioned above. PMID:15900666

Srinivasan, P; Raman, Anand; Sharma, D N

2002-04-01

214

Construction and testing of a neutron and gamma spectrometry system using pulse shape discrimination with an organic scintillator  

NASA Astrophysics Data System (ADS)

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 scintillator NE-213 was used. The primary neutron/gamma sources used were 78-mCi and 4.7-Ci Pu-239Be sources, while 4.7-micro-Ci and 97.6-micro-Ci Na-22 gamma sources were used for energy calibration and additional testing of the detector. Proton recoil spectra and Compton electron spectra were unfolded with the neutron and gamma unfolding code FORIST to generate the incident neutron and gamma spectra, respectively. FORIST, which was written for a CDC computer, was modified to run on a VAX 6420. The experimental spectra were compared to those in the literature. The locations of the peaks in the Pu-239Be spectrum agreed with the literature to within 8.3%, the Pu-239Be gamma spectrum agreed to within 0.7%, while the Na-22 gamma spectrum agreed exactly. Uncertainties in the detection system and unfolding procedure are on the order of 5-10%. This thesis is intended to be a summary of the relevant literature and a user's guide to the PSD spectrometer.

Pope, Robert S.

1993-03-01

215

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

Microsoft Academic Search

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. This 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

A. E. Egger; M. H. Putnam; R. G. Helmer; A. J. Caffrey; R. C. Greenwood

1995-01-01

216

On the categorization of uranium materials using low resolution gamma ray spectrometry.  

PubMed

In order to characterize uranium materials during e.g. nuclear safeguards inspections and in initial stages of nuclear forensic investigations, hand-held low resolution gamma ray detection instruments with automatic uranium categorization capabilities may be used. In this paper, simulated response curves for a number of matrices applied on NaI(Tl) scintillation detector spectra show that the result of the categorization is strongly dependent on the physical properties of the uranium material. Recommendations on how to minimize the possibility of misclassification are discussed. PMID:23208231

Vesterlund, A; Ulvsand, T; Lidström, K; Skarnemark, G; Ekberg, C; Ramebäck, H

2012-11-02

217

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

NASA Astrophysics Data System (ADS)

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

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

2006-05-01

218

A First Application of the FRAM Isotopic Analysis Code to High-Resolution Microcalorimetry Gamma-Ray Spectra  

Microsoft Academic Search

Gamma-ray spectrometry systems based on High-Purity Germanium (HPGe) have been the long-standing leader in terms of resolution since their introduction many years ago. The application of this technology to the spectroscopic assay of special nuclear material led to the development of several isotopic analysis tools, including the advanced software package FRAM, which was, and continues to be, developed at Los

Pete J. Karpius; Duc Vo; Minesh Bacrania; James Beall; Douglas Bennett; Randy W. Doriese; Gene Hilton; Andrew Hoover; Robert Horansky; Kent Irwin; Michael Rabin; Carl Reintsema; Cliff Rudy; J. N. Ullom; Leila Vale

2009-01-01

219

Spectra And Time Scales For Particle Acceleration In Ultra-Relativistic Flows Applicable To Gamma-Ray Bursters  

NASA Astrophysics Data System (ADS)

Monte-Carlo computations of ultra-relativistic parallel and oblique shock acceleration is presented for upstream flow gamma factors, Gamma=(1-Vup}2/c2)-0.5 up to Gamma~1000, relevant to Gamma-ray burst (GRB) fireballs. For oblique sub-luminal shocks, the spectra depend on whether or not the upstream scattering is small angle with delta theta < Gamma-1 or isotropic, which is possible if lambda > rg Gamma where lambda is the scattering mean free path along the field line and rg the gyroradius. The large angle case exhibits distinctive structure in the basic power-law spectrum not nearly so obvious for small angle scattering but both cases yield a significant speed-up of acceleration rate when compared with the conventional, non-relativistic expression, tacc=[c/Vup-Vdown] [lambdaup/Vup+lambdadown/Vdown]. The Gamma2 energisation factor per shock crossing, important in the Vietri work on GRB ultra-high energy neutrino, and possibly cosmic ray and gamma-ray output, is supported for the first crossing cycle but the factor is less subsequently. Super-luminal shock results are discussed in a companion paper (these proceedings, Meli and Quenby, 2001).

Meli, A.; Quenby, J. J.

2001-08-01

220

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

221

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

Microsoft Academic Search

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

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

2006-01-01

222

Assessment of on-line burnup monitoring of pebble bed reactor fuel using passive gamma-ray spectrometry  

Microsoft Academic Search

An investigation was performed to assess the feasibility of passive gamma-ray spectrometry assay as an approach for on-line burnup determination for the Modular Pebble Bed Reactor (MPBR). In addition to its inherently safe design, a unique feature of this reactor is its multipass fuel cycle in which graphite fuel pebbles are randomly loaded and continuously circulated through the core until

Ayman I. Hawari; Jianwei Chen; Bingjing Su; Zhongxiang Zhao

2002-01-01

223

On the determination of 226 Ra in soils and uranium ores by direct gamma-ray spectrometry  

Microsoft Academic Search

The evaluation of the source term in facilities related to the first stages of nuclear fuel involves the determination of radium concentration, as well as those from other radionuclides members of the uranium series. These activities are often required within a short time period, making impossible the use of radiochemical methods or the gamma-ray spectrometry of radium daughters. In those

A. Martinez Lobo; J. Palomares

1991-01-01

224

Calculation of “LS-curves” for coincidence summing corrections in gamma ray spectrometry  

NASA Astrophysics Data System (ADS)

When coincidence summing correction factors for extended samples are calculated in gamma-ray spectrometry from full-energy-peak and total efficiencies, their variation over the sample volume needs to be considered. In other words, the correction factors cannot be computed as if the sample were a point source. A method developed by Blaauw and Gelsema takes the variation of the efficiencies over the sample volume into account. It introduces the so-called LS-curve in the calibration procedure and only requires the preparation of a single standard for each sample geometry. We propose to replace the standard preparation by calculation and we show that the LS-curves resulting from our method yield coincidence summing correction factors that are consistent with the LS values obtained from experimental data.

Vidmar, Tim; Korun, Matjaž

2006-01-01

225

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

226

The Sandwich spectrometer for ultra low-level gamma-ray spectrometry.  

PubMed

The technical details and performance of the newly developed Sandwich spectrometer for ultra low-level gamma-ray spectrometry are presented. The spectrometer, which consists of two HPGe detectors, an active muon shield and a lead/copper shield with a convenient and rapid opening mechanism, is located in an underground laboratory at a depth of 500 m water equivalent. The data is collected in list mode, which enables off-line data analysis to identify muon-induced events and possible Ge detector crosstalk due to Compton scattering. The background count-rate from 40 to 2700 keV normalised to the mass of the Ge crystals is 220 day(-1)kg(-1). PMID:19246202

Wieslander, J S Elisabeth; Hult, Mikael; Gasparro, Joël; Marissens, Gerd; Misiaszek, Marcin; Preusse, Werner

2009-01-23

227

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

228

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

229

Recovery of the energy spectra of the gamma rays and electrons accelerated in the electrical fields of the thunderclouds  

NASA Astrophysics Data System (ADS)

The particle detectors of the Aragats space environmental center (ASEC) in Armenia measures not only enhanced count rates of the electrons and gamma rays during thunderstorms, but also energy deposits of the particles in networks of the thick plastic scintillators and NaI detectors. The 1-minute histograms of energy deposit, taken during thunderstorm ground enhancements (TGEs) lasting up to 10 minutes with Monte Carlo techniques are recovered to energy spectra of particles fallen on the roof of the building where networks of particle detectors are located. The gamma ray energy spectra of the 2 largest TGE events in 19 September 2009 and 4 October 2010 demonstrate power low shape and prolong up to 100 MeV. The energy spectra of electrons have power law shape. Comparisons of the obtain TGE particle fluxes with "background" cosmic ray flux on the altitude of 3200 m proves that electrons and gamma rays up to 40-50 MeV was accelerated in the avalanche process in thunderclouds (Runaway breakdown, RB), the elongation of the spectra up to 100 MeV is due to acceleration of cosmic ray electrons in the electrostatic fields of the thunderclouds. For these electrons the energy/field strength relation do not support the initiation of the RB process.

Chilingarian, A.; MAilyan, B.

2011-12-01

230

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

NASA Astrophysics Data System (ADS)

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

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

2004-10-01

231

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

232

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); Furuya, Yoshio [Nagasaki Univ. (Japan)

1999-02-05

233

Gamma-ray Spectra & Variability of Crab Nebula Emission Observed by BATSE  

NASA Astrophysics Data System (ADS)

We report ˜600 days of BATSE earth-occultation observations of the total gamma-ray (30 keV to 1.7 MeV) emission from the Crab Nebula, between 1991 May 24 (TJD 8400) and 1994 October 2 (TJD 9627). Lightcurves from \\{35--100, 100--200, 200--300, 300--400, 400--700, and 700--1000\\} keV, show that positive fluxes were detected by BATSE in each of these six energy bands at significances of approximately \\{ 31, 20, 9.2, 4.5, 2.6, and 1.3\\} sigma, respectively, per day. We also observed significant flux and spectral variations in the 35--300 keV energy region, with time scales of days to weeks. The spectra below 300 keV, averaged over typical CGRO viewing periods of 6--13 days, can be well described by a broken power law with average indices of ˜2.1 and ˜2.34 varying around a spectral break at ˜100 keV. Above 300 keV, the long-term averaged spectra, averaged over three 400 d periods (TJD 8400-8800, 8800-9200, and 9200-9600, respectively) are well represented by the same power law, extrapolated from low energies up to ˜670 keV, plus a hard spectral component extending from ˜670 keV to ˜1.7 MeV, with a spectral index of ˜1.75. The latter component could be related to a complex structure observed by COMPTEL in the 0.7-3 MeV range. Above 3 MeV, the extrapolation of the power-law continuum determined by the low-energy BATSE spectrum is consistent with fluxes measured by COMPTEL in the 3-25 MeV range, and by EGRET from 30-50 MeV. We interpret these results as synchrotron emission produced by the interaction of particles ejected from the pulsar with the field in different dynamical regions of the nebula system, as observed recently by HST, XMM-Newton, and Chandra.

Ling, J. C.; Wheaton, Wm. A.

2003-03-01

234

Numerical simulations of planetary gamma-ray spectra induced by galactic cosmic rays  

SciTech Connect

The fluxes of cosmic-ray-produced gamma rays escaping from Mars were calculated using the LAHET Code System and basic nuclear data for {gamma}-ray production. Both surface water content and atmospheric thickness strongly affect the fluxes of {gamma}-ray lines escaping from Mars.

Masarik, J.; Reedy, R.C.

1994-07-01

235

Short versus long gamma-ray bursts: spectra, energetics, and luminosities  

NASA Astrophysics Data System (ADS)

We compare the spectral properties of 79 short and 79 long Gamma-Ray Bursts (GRBs) detected by BATSE and selected with the same limiting peak flux. Short GRBs have a low-energy spectral component harder and a peak energy slightly higher than long GRBs, but no difference is found when comparing short GRB spectra with those of the first 1-2 s emission of long GRBs. These results confirm earlier findings for brighter GRBs. The bolometric peak flux of short GRBs correlates with their peak energy in a similar way to long bursts. Short and long GRBs populate different regions of the bolometric fluence-peak energy plane, short bursts being less energetic by a factor similar to the ratio of their durations. If short and long GRBs had similar redshift distributions, they would have similar luminosities yet different energies, which correlate with the peak energy E_peak for the population of long GRBs. We also test whether short GRBs are consistent with the E_peak-E_iso and E_peak-L_iso correlations for the available sample of short (6 events) and long (92 events) GRBs with measured redshifts and E^obs_peak: while short GRBs are inconsistent with the E_peak-E_iso correlation of long GRBs, they could follow the E_peak-L_iso correlation of long bursts. All the above indications point to short GRBs being similar to the first phases of long bursts. This suggests that a similar central engine (except for its duration) operates in GRBs of different durations.

Ghirlanda, G.; Nava, L.; Ghisellini, G.; Celotti, A.; Firmani, C.

2009-03-01

236

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

PubMed

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

Paul, Sabyasachi; Sarkar, P K

2012-08-11

237

Gamma-Ray Spectrum Catalogue. Ge(Li) and Si(Li) Spectrometry. Volume 2. Third Edition.  

National Technical Information Service (NTIS)

A new edition of the Gamma-Ray Spectrum Catalogue has been issued. The second volume of this edition which is being released at this time is devoted to the presentation of experimental pulse-amplitude spectra obtained with Ge(Li) and Si(Li) spectrometers....

R. L. Heath

1974-01-01

238

In situ gamma-ray spectrometry in forests: determination of kerma rate in air from 137Cs  

Microsoft Academic Search

A method is presented to determine the kerma rate in air from 137Cs due to Chernobyl fallout in forests. In situ gamma-ray spectra from several forest sites in Russia, in the Ukraine and in Southern Germany are evaluated with the aim of deducing the ratio of primary and forward scattered photons for 137Cs. With this ratio and the results of

F. Gering; P. Kiefer; S. Fesenko; G. Voigt

2002-01-01

239

Primary proton and muon spectra estimated from atmospheric gamma rays observed at balloon altitude  

Microsoft Academic Search

From 1968 to 1998 we have observed atmospheric gamma rays up to 10TeV with total exposure of 6.46m^2 sr day using emulsion chambers at balloon altitude. On the balloon observation in 2001, we adopted an automatic scanning method and successfully observed atmospheric gamma rays down to 30GeV. Since these atmospheric gamma rays at high altitude of several g\\/cm^2 are almost

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

2004-01-01

240

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

241

Gamma-ray spectrometry of ultra low levels of radioactivity within the material screening program for the GERDA experiment.  

PubMed

In present and future experiments in the field of rare events physics a background index of 10(-3) counts/(keV kg a) or better in the region of interest is envisaged. A thorough material screening is mandatory in order to achieve this goal. The results of a systematic study of radioactive trace impurities in selected materials using ultra low-level gamma-ray spectrometry in the framework of the GERDA experiment are reported. PMID:19243966

Budjás, D; Gangapshev, A M; Gasparro, J; Hampel, W; Heisel, M; Heusser, G; Hult, M; Klimenko, A A; Kuzminov, V V; Laubenstein, M; Maneschg, W; Simgen, H; Smolnikov, A A; Tomei, C; Vasiliev, S I

2009-01-21

242

Classification of soil samples according to their geographic origin using gamma-ray spectrometry and principal component analysis  

Microsoft Academic Search

A principal component analysis (PCA) was used for classification of soil samples from different locations in Serbia and Montenegro. Based on activities of radionuclides (226Ra, 238U, 235U, 40K, 134Cs, 137Cs, 232Th and 7Be) detected by gamma-ray spectrometry, the classification of soils according to their geographical origin was performed. Application of PCA to our experimental data resulted in satisfactory classification rate

Snežana Dragovi?; Antonije Onjia

2006-01-01

243

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

Microsoft Academic Search

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

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

2008-01-01

244

Gamma-ray spectrometry across the Upper Devonian basin succession at Kowala in the Holy Cross Mountains (Poland)  

Microsoft Academic Search

The Upper Devonian sequence at Kowala in the Holy Cross Mountains was logged using gamma-ray spectrometry, for investigating the changes of oxygenation level in the Late Devonian basin. The Th\\/U ratio indicates that oxygen levels were low throughout the Late Frasnian interval, with low peaks during the Kellwasser Events showing anoxic conditions in the basin. The F-F boundary interval was

DAVE BOND

245

Classification of soil samples according to geographic origin using gamma-ray spectrometry and pattern recognition methods  

Microsoft Academic Search

Multivariate data analysis methods were used to recognize and classify soils of unknown geographic origin. A total of 103 soil samples were differentiated into classes, according to regions in Serbia and Montenegro from which they were collected. Their radionuclide (226Ra, 238U, 235U, 40K, 134Cs, 137Cs, 232Th and 7Be) activities detected by gamma-ray spectrometry were then used as the inputs in

Snezana Dragovic; Antonije Onjia

2007-01-01

246

Broad-band X-ray\\/gamma-ray spectra and binary parameters of GX 339-4 and their astrophysical implications  

Microsoft Academic Search

We present X-ray\\/gamma-ray spectra of the binary GX 339-4 observed in the hard state simultaneously by Ginga and CGRO OSSE during an outburst in 1991 September. The Ginga X-ray spectra are well represented by a power law with a photon spectral index of Gamma~=1.75 and a Compton reflection component with a fluorescent Fe Kalpha line corresponding to a solid angle

Andrzej A. Zdziarski; Juri Poutanen; Joanna Mikolajewska; Marek Gierlinski; Ken Ebisawa; W. Neil Johnson

1998-01-01

247

Prompt-gamma spectrometry for the optimization of reactor neutron beams in biomedical research  

SciTech Connect

In order to select the optimal spectral composition and size for the reactor neutron beams applied to in vivo analysis and therapy in biomedical research it is necessary to determine the spatial slow-neutron flux distributions produced by the beam in the irradiated object and to calculate or measure the neutron dose equivalents of both the original spectrum and the moderated neutrons. In this study the maximum neutron dose equivalents are found by spectrometry of the prompt-..gamma.. emission from the interaction of neutrons with atomic nuclei in the irradiated object. Different spectral distributions were produced by using an unfiltered beam together with filters of quartz, cadmium, /sup 10/B, iron, aluminum, and sulfur. The phantom used was a tank filled with an aqueous solution of urea. Cadmium-containing organs were simulated. For in vivo neutron-activation analysis of human tissues at a depth of 2-5 cm it was found advisable to use neutrons of 20-40 keV mean energy with a beam area of at least 45 cm/sup 2/.

Borisov, G.I.; Komkov, M.M.; Leonov, V.F.

1988-06-01

248

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

249

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

250

Analysis of gamma-irradiated melon, pumpkin, and sunflower seeds by electron paramagnetic resonance spectroscopy and gas chromatography-mass spectrometry.  

PubMed

Seeds of melon (Citrullus lanatus var. sp.), pumpkin (Cucurbita moschata), and sunflower (Heliantus annus) were gamma-irradiated at 1, 3, 5, and 10 kGy and analyzed by electron paramagnetic resonance (EPR) and gas chromatography-mass spectrometry (GC-MS) according to EN1787:2000 and EN1785:2003, respectively. Distinguishable triplet signals due to the presence of induced cellulose radicals were found at 2.0010-2.0047 g in the EPR spectra. The gamma-irradiated radiolytic markers of 2-dodecylcyclobutanone (2-DCB) and 2-tetradecylcyclobutanone (2-TCB) were identified in all irradiated seed samples. Both the free radicals and the alkylcyclobutanones were found to increase with irradiation dose. In general, linear relationships between the amount of radicals and irradiation dosage could be established. Studies at an ambient temperature (20-25 degrees C) in a humidity-controlled environment showed a complete disappearance of the cellulosic peaks for irradiated samples upon 60 days of storage. Such instability behavior was considered to render the usefulness of using EPR alone in the determination of irradiated seed samples. On the other hand, 2-DCB and 2-TCB were also found to decompose rapidly (>85% loss after 120 days of storage), but the radiolytic markers remained quantifiable after 120 days of postirradiation storage. These results suggest that GC-MS is a versatile and complimentary technique for the confirmation of irradiation treatment to seeds. PMID:16968077

Sin, Della W M; Wong, Yiu Chung; Yao, Wai Yin

2006-09-20

251

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

SciTech Connect

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

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

1988-01-01

252

Verification of the 239Pu content, isotopic composition and age of plutonium in Pu–Be neutron sources by gamma-spectrometry  

Microsoft Academic Search

A non-destructive, gamma-spectrometric method for verifying the plutonium content of Pu–Be neutron sources has been developed. Gamma-spectra were taken in the far-field of the sample, which was assumed to be cylindrical. The Pu content of the sources was evaluated from the count rates of the gamma-peaks of 239Pu, relying on the assumption that the gamma-rays are coming to the detector

Cong Tam Nguyen

2006-01-01

253

Verification of the 239Pu content, isotopic composition and age of plutonium in Pu Be neutron sources by gamma-spectrometry  

Microsoft Academic Search

A non-destructive, gamma-spectrometric method for verifying the plutonium content of Pu Be neutron sources has been developed. Gamma-spectra were taken in the far-field of the sample, which was assumed to be cylindrical. The Pu content of the sources was evaluated from the count rates of the gamma-peaks of 239Pu, relying on the assumption that the gamma-rays are coming to the

Cong Tam Nguyen

2006-01-01

254

Gamma spectrometry of EFTTRA T2BIS R280.2. Gamma scan wires 6 through 10.  

National Technical Information Service (NTIS)

In the frame work of the EFTTRA programme on recycling of actinides and fission products, five gamma scan wires which were included in the experiment R280.2 T2bis have been examined by gamma scanning. The results of the measurements have been described in...

G. Dassel H. A. Buurveld J. C. Plakman

1996-01-01

255

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

256

Identification of fissile materials from fission product gamma-ray spectra  

Microsoft Academic Search

A new active–passive nondestructive assay technique has been developed to identify fissile materials by observing the gamma-ray emissions from induced fission products. This technique entails using a neutron source to induce fissions in unknown containerized fissile materials and to subsequently observe high energy peaks (>800keV) in the fission product gamma-ray spectrum. Ratios of the observed peak intensities are then formed.

D. H Beddingfield; F. E Cecil

1998-01-01

257

Hints of the Existence of Axion-Like-Particles From the Gamma-Ray Spectra of Cosmological Sources  

SciTech Connect

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

Sanchez-Conde, M.A.; /IAA, Granada /SLAC; Paneque, D.; Bloom, E.; /KIPAC, Menlo Park; Prada, F.; /IAA, Granada /UC, Santa Cruz; Dominguez, A.; /IAA, Granada /Seville U.

2009-06-23

258

A statistical approach to the choice of channel-width in gamma-ray spectrometry using empirical relations between resolution and gamma-ray energy  

Microsoft Academic Search

The problem of extra peak-broadening caused by the finite channel-width in multichannel gamma-ray spectrometry is discussed,\\u000a using empirical equations for the relations between resolution and energy for NaI(T1) scintillation detectors and Ge(Li) drift\\u000a detectors. Relations are derived and graphs designed to estimate the extra peak-broadening at a certain energy, caused by\\u000a the compromise necessary when using a chosen energy scale

R. Furler; H. Poppe

1974-01-01

259

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

2008-03-13

260

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

261

Determination of Radioactivity in Multibelled Samples by Computer-Aided Automatic gamma and beta -Spectrometry.  

National Technical Information Service (NTIS)

A computer and a multichannel analyzer have been coupled to an automatic gamma -counter and a liquid scintillation counter to determine the radioactivity in multilabelled gamma and beta -emitting samples. Both quantitative and qualitative analyses can be ...

D. Mascanzoni

1980-01-01

262

Solubilized liquid scintillator for beta spectrometry and gamma dosimetry of uniformly distributed gamma sources in aqueous solutions  

Microsoft Academic Search

The detection and the spectrometry of $beta$-radiation in aqueous ; solutions by the scintillation counting technique is studied with a water ; fraction (30-100%) high enough to bar the use of the scintillators otherwise ; customarily employed. The following possibilities are investigated and ; delineated in terms of their applicabilities: 1) Cerenkov count. 2) Emulsion ; count (emulsification of a

Lahmann

1974-01-01

263

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

264

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

Microsoft Academic Search

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

Andrew S. Friedman; Joshua S. Bloom

2005-01-01

265

Principal Component Analysis of Gamma-Ray Spectra for Radiation Portal Monitors  

Microsoft Academic Search

The scanning of cargo for radiological and nuclear material is vital in detecting the illicit trafficking of such materials. The deployment of technologies such as Radiation Portal Monitors (RPMs) has enabled screening for the presence of gamma and neutron emitting radionuclides.

David Boardman; Mark Reinhard; Alison Flynn

2012-01-01

266

Production of beta-gamma coincidence spectra of individual radioxenon isotopes for improved analysis of nuclear explosion monitoring data  

NASA Astrophysics Data System (ADS)

Radioactive xenon gas is a fission product released in the detonation of nuclear devices that can be detected in atmospheric samples far from the detonation site. In order to improve the capabilities of radioxenon detection systems, this work produces beta-gamma coincidence spectra of individual isotopes of radioxenon. Previous methods of radioxenon production consisted of the removal of mixed isotope samples of radioxenon gas released from fission of contained fissile materials such as 235U. In order to produce individual samples of the gas, isotopically enriched stable xenon gas is irradiated with neutrons. The detection of the individual isotopes is also modeled using Monte Carlo simulations to produce spectra. The experiment shows that samples of 131mXe, 133 Xe, and 135Xe with a purity greater than 99% can be produced, and that a sample of 133mXe can be produced with a relatively low amount of 133Xe background. These spectra are compared to models and used as essential library data for the Spectral Deconvolution Analysis Tool (SDAT) to analyze atmospheric samples of radioxenon for evidence of nuclear events.

Haas, Derek Anderson

267

Angular distribution of proton leakage from a fusion plasma using ultra low-level gamma-ray spectrometry.  

PubMed

This experiment aimed at studying a technique to measure the leakage of charged particles from a fusion plasma. The activity induced in samples of various materials placed on a special holder inside a Tokamak was measured using ultra low-level gamma-ray spectrometry (ULGS) performed in three underground laboratories. In total, 27 radionuclides were detected in this experiment. Seven of these radionuclides were mainly produced by proton interactions. For two of them it was possible to determine their angular distribution. PMID:19962906

de Orduña, R González; Hult, M; Bonheure, G; Arnold, D; Dombrowski, H; Laubenstein, M; Wieslander, J S E; Vidmar, T; Vermaercke, P

2009-11-13

268

Poluchenie veroyatnostnykh otsenok nekotorykh priznakov obraza pika polnogo pogloshcheniya v mnogokanal'noj gamma-spektrometrii. (Determination of probabilistic evaluations of some pattern's signs of full absorption peak in multichannel gamma-ray spectrometry).  

National Technical Information Service (NTIS)

The expressions for calculation of probabilistic evaluations of full absorption peak (FAP) pattern's some signs in experimental (gamma)-spectra are obtained. These signs are FAP maximum stability, displacement of FAP maximum, rejection of FAP pattern's fo...

M. V. Stets D. I. Sikora

1989-01-01

269

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

270

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

Microsoft Academic Search

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

Vladimir A. Basiuk

1999-01-01

271

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

Microsoft Academic Search

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

David Harris Beddingfield

1996-01-01

272

[The triboluminescent spectra of the blood of gamma-irradiated rats].  

PubMed

Triboluminescence (TL) of rat blood 3 h after whole-body single exposure to gamma-radiation (0.25, 1, 3, and 5 Gy) exhibited positive coefficient of correlation r = 0.99 (at a wave length of 412 nm) with radiation dose. The effect of ionizing radiation on the animal body caused changes in blood TL within the fixed areas of the spectral range, whose fluctuation parameters were conditioned by specifically significant radiobiological changes and nonspecific adaptive reactions. PMID:1887011

Orel, V E; Dziatkovskaia, N N; Afonin, A N; Mazurik, V K

273

Surrogate Reaction Measurements of Fission gamma-ray Spectra with Liberace and STARS  

Microsoft Academic Search

Very few high-resolution measurements have been made of the prompt gamma-ray spectrum following non-spontaneous fission. However, this information is useful for stockpile stewardship and can also provide a wealth of information about the fission process. Recent experiments using STARS+LIBERACE at the 88-Inch cyclotron designed to determine surrogate neutron-induced cross sections in the Uranium isotopic chain have also produced a wide

C. C. Jewett; S. R. Lesher; J. T. Burke; C. W. Beausang; L. A. Bernstein; H. Ai; J. A. Church; R. M. Clark; M. A. Deleplanque; F. S. Dietrich; J. Escher; P. Fallon; I. Y. Lee; B. F. Lyles; A. O. Macchiavelli; M. A. McMahan; K. J. Moody; E. B. Norman; L. Phair; E. Rodriguez-Vieitez

2006-01-01

274

Introducing HYPERMET-PC for automatic analysis of complex gamma-ray spectra  

Microsoft Academic Search

In short time activation analysis prompt gamma-activation analysis and in high rate -ray spectroscopy in general, the shape parameters for peaks and back ground usually vary, rendering spectrum evaluation codes based on a fixed shape calibration unsuitable. An interactive version of the well-known, fully automatic -ray spectrum analysis code HYPERMET has been developed in C ++ for the IBM-PC. It

B. Fazekas; G. Molnár; T. Belgya; L. Dabolczi; A. Simonits

1997-01-01

275

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

276

The holistic analysis of gamma-ray spectra in instrumental neutron activation analysis  

NASA Astrophysics Data System (ADS)

A method for the interpretation of ?-ray spectra as obtained in INAA using linear least squares techniques is described. Results obtained using this technique and the traditional method previously in use at IRI are compared. It is concluded that the method presented performs better with respect to the number of detected elements, the resolution of interferences and the estimation of the accuracies of the reported element concentrations. It is also concluded that the technique is robust enough to obviate the deconvolution of multiplets.

Blaauw, Menno

1994-12-01

277

Positive SNM Gamma Detection Achieved Through Synthetic Enhancement of Sodium Iodide Detector Spectra  

Microsoft Academic Search

We have developed a new algorithm, ASEDRA, to post-process scintillator detector spectra to render photopeaks with high accuracy. ASEDRA, or ldquoAdvanced Synthetically Enhanced Detector Resolution Algorithm,rdquo is currently applied to NaI(Tl) detectors, which are robust, but suffer from poor energy resolution. ASEDRA rapidly post-processes a NaI(Tl) detector spectrum over a few seconds on a standard laptop without prior knowledge of

G. E. Sjoden; R. Detwiler; E. LaVigne; J. E. Baciak Jr.

2009-01-01

278

Remarks on the analysis of the photopeaks of scintillation gamma-ray spectra  

Microsoft Academic Search

Physical considerations permit the asymmetry of the photopeak in scintillation ?-spectra to be represented by a second Gaussian\\u000a peak of lower intensity, accompanying the principal peak. The problem of finding the peak parameters is described as one reduced\\u000a to solving an over-determined system of non-linear equations, when the numbers of counts in the channels of the analyzer are\\u000a given. The

Ch. Stoyanov; L. Aleksandrov; V. Gadjokov

1972-01-01

279

Dark Matter Content in Q-Cosmology and Its Detectability in Anisotropy of Cosmic Gamma-Ray Spectra  

NASA Astrophysics Data System (ADS)

Dissipative Liouville cosmology (Q-Cosmology) introduces the effect of the dilaton field and central charge deficit on relic density of cold dark matter (CDM). The result is a reduction factor of 10 of the relic density, as compared to the value obtained in ordinary cosmology (Lahanas et al, 2007). Since dark matter particles are weakly interacting, annihilation can only occur in regions with high density, such as dark matter halos. Previous works on the anisotropy of the cosmic gamma-ray background (CGB) have shown that dark matter annihilation can be separated from the known background in the anisotropy data (Endo, Komatsu, 2007). In this talk, we first explain the dark matter content of the universe in Q-Cosmology and then study the detectability of this new model in the anisotropy of the cosmic gammy-ray spectra.

Truong, Phuongmai; Dutta, Bhaskar; Campbell, Sheldon; Krislock, Abram

2007-10-01

280

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

SciTech Connect

We present new parameterizations of energy spectra of secondary particles, {pi} 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=E{sub i}/E{sub p}--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 {pi}-meson production.

Kelner, S. R. [Moscow Institute of Engineering Physics, Kashirskoe sh. 31, Moscow, 115409 (Russian Federation); Aharonian, F. A. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-6917 Heidelberg (Germany); Bugayov, V. V. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-6917 Heidelberg (Germany); Department of Physics, Altai State University, 656049 Barnaul (Russian Federation)

2006-08-01

281

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

282

Establishing the existence of harmonically-spaced lines in gamma-ray burst spectra using Bayesian inference. [GB 870303  

SciTech Connect

We use a rigorous method derived from Bayesian inference to establish the existence of lines in the spectra of [gamma]-ray bursts. Line detection involves a comparison of nested models. The method amounts to the calculation of the odds [ital O] favoring models with lines over models without lines. [ital O] is given by the product of the maximum likelihood ratio and a second factor which includes the ratio of the posterior uncertainty of the line parameters to their prior uncertainty. The maximum likelihood ratio always favors the more complex model, since the likelihood of the more complex model can never be larger than that of the simpler model. The second factor penalizes the more complex model, since the posterior uncertainty for the extra parameters is generally smaller than their prior uncertainty. Thus an Ockham's Razor'' automatically appears in Bayesian model comparison.

Graziani, C.; Lamb, D.Q. (Department of Astronomy and Astrophysics University of Chicago, Chicago, IL 60637 (United States)); Loredo, T.J. (CRSR, Cornell University, NY 14853 (United States)); Fenimore, E.E. (Los Alamos National Laboratory, NM 87545 (United States)); Murakami, T. (Institute of Space and Astronautical Research (Japan)); Yoshida, A. (Institute of Physical and Chemical Research (Japan))

1993-07-05

283

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

Microsoft Academic Search

Undoped and CuO-doped lithium phosphate, lead phosphate and zinc phosphate glasses were prepared. UV-visible and infrared absorption spectra of the prepared samples were measured before and after successive gamma irradiation. Experimental optical spectra of the undoped samples reveal strong UV absorption bands, which are attributed to the presence of trace iron impurities in both the lithium and zinc phosphate glasses

H. A. Elbatal; A. M. Abdelghany; F. H. Elbatal; Kh. M. Elbadry; F. A. Moustaffa

2011-01-01

284

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

Microsoft Academic Search

Undoped and CuO-doped lithium phosphate, lead phosphate and zinc phosphate glasses were prepared. UV–visible and infrared absorption spectra of the prepared samples were measured before and after successive gamma irradiation. Experimental optical spectra of the undoped samples reveal strong UV absorption bands, which are attributed to the presence of trace iron impurities in both the lithium and zinc phosphate glasses

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

2011-01-01

285

The average X-ray\\/gamma-ray spectra of Seyfert galaxies from GINGA and OSSE and the origin of the cosmic X-ray background  

Microsoft Academic Search

We have obtained the first average 2-500 keV spectra of Seyfert galaxies, using the data from Ginga and Compton Gamma-Ray Observatory's (CGRO) Oriented Scintillation Spectrometer Experiment (OSSE). Our sample contains three classes of objects with markedly different spectra: radio-quiet Seyfert 1's and 2's, and radio-loud Seyfert 1's. The average radio-quiet Seyfert 1 spectrum is well-fitted by a power law continuum

Andrzej A. Zdziarski; W. Neil Johnson; Chris Done; David Smith; Kellie McNaron-Brown

1995-01-01

286

Resonance-spin memory in low-energy-gamma-ray spectra from Sb, Tb, Ho, and Ta odd-odd compound nuclei  

Microsoft Academic Search

The low-energy-gamma-ray spectra from neutron resonance capture with natural samples of Sb, Tb, Ho, and Ta were measured using\\u000a the HPGe detector at the IBR-30 pulsed reactor at the JINR, Dubna. The resonance-spin-memory effect in the spectra from the\\u000a odd-odd compound nuclei of 122Sb, 169Tb, and 166Ho was found to be quite distinct. For the 182Ta compound nucleus, it proved

U. Olejniczak; N. A. Gundorin; L. B. Pikelner; M. Przytu?a; D. G. Serov

2002-01-01

287

Automated Complex for Information Retrieval and Processing in the gamma-Resonance Spectrometry.  

National Technical Information Service (NTIS)

A complex for information retrieval and processing in the Moessbauer effect spectrometry is described. The complex consists of a set of 4 precision spectrometers nad a program system for the computation of Moessbauer effect spectrum. High velocity accurac...

V. N. Belogurov V. A. Bylinkin

1977-01-01

288

Gamma-Fe2O3 nanopowders synthesized in microwave plasma and extraordinarily strong temperature influence on their Mössbauer spectra.  

PubMed

The article reports on two nanopowders synthesized in microwave plasma: the first sample was synthesized in a torch discharge at 1 bar and the second sample was synthesized in low-pressure plasma at 40 mbar. Morphology, composition and properties of the powders were studied by TEM, XRD, Raman and Mössbauer spectroscopies, and magnetic measurements. In the XRD patterns of the samples only gamma-Fe2O3 was identified (mean crystallite size d(XRD) was 24 nm for the first sample and 13 nm for the second sample). Based on the Mössbauer spectra measured at 5 K, the presence of other iron oxide phases was excluded in both samples. Unusually strong temperature dependence of the Lamb-Mössbauer factor was observed: I(SA)(5 K)/I(SA)(293 K) = 6 in the case of the first sample and I(SA)(5 K)/I(SA)(293 K) = 22 for the second sample (I(SA) denotes integral spectrum area). This effect is explained as the consequence of the reduced agglomeration of electrically charged nanoparticles in the plasma, i.e., particles can either move at 293 K (when they are free) or tilt (if they are a part of a chain). Superparamagnetic phase was not observed in the room-temperature Mössbauer spectra of both samples. PMID:23447989

David, B; Pizúrová, N; Schneeweiss, O; Santavá, E; Kudrle, V; Jasek, O

2012-12-01

289

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

Microsoft Academic Search

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

D. C. Camp; H. E. Martz

1991-01-01

290

Close-geometry efficiency calibration in gamma-ray spectrometry using radio-nuclides with a two-step cascade decay  

Microsoft Academic Search

When efficiency calibration is performed in gamma-ray spectrometry with point sources in close geometry, radio-nuclides emitting photons of a single energy are usually utilized in order to avoid problems arising from true coincidence summing. Radio-nuclides emitting gamma-rays in a simple two-step cascade are therefore not considered suitable for such measurements. It is, namely, not possible to determine the full-energy-peak and

T. Vidmar; M. Korun; A. Likar

2003-01-01

291

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

292

Contributions of gamma-ray spectrometry to terrestrial impact crater studies: The example of Serra da Cangalha, northeastern Brazil  

NASA Astrophysics Data System (ADS)

Several geophysical methods have been used for decades for the identification and exploration of impact craters. Most of them are based on seismic, potential fields and electrical data, focusing on exploration of anomalies caused by changes in physical properties or by structures associated with the formation of the crater. Gamma-ray spectrometry is usually not mentioned among the geophysical methods employed in crater studies, although it is known that impact cratering processes cause a number of physical/chemical changes in the country rocks. These changes include the remobilization of hydrothermal fluids which directly modify the composition of target rocks and, subsidiarily, of soils related to these rocks. Therefore, the distribution of radioactive elements K, Th and U has the potential to map such modifications. We present the analysis of gamma-ray signatures at the Serra da Cangalha impact structure, located in northeastern Brazil, using methods for enhancing K anomalies and also the overall gamma-ray signatures. These results provide valuable information on the distinct zones within the crater and might contribute to the understanding of hydrothermal enrichment processes produced as a result of the impact event.

Vasconcelos, Marcos Alberto R.; Leite, Emilson P.; Crósta, Alvaro P.

2012-02-01

293

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

SciTech Connect

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

W. H. Zhang; A. Chatt

2000-11-12

294

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

295

Magnetometry, Radiometry and gamma Spectrometry of the Janjao Diatreme, Lages, State of Santa Catarina, Brazil.  

National Technical Information Service (NTIS)

Magnetic, radiometric and gamma spectrometric surveys have been carried out on the Janjao diatreme which outcrops near Lajes in central-east Santa Catarina State, Brazil. The body is deeply weathered on the surface and its concentrates contain serpentiniz...

D. P. Svisero

1985-01-01

296

Isotopic analysis of uranium by neutron activation and high resolution gamma ray spectrometry  

Microsoft Academic Search

A method is described for the non-destructive and accurate determination of the isotopic composition of uranium by activation\\u000a analysis. The high resolving power of Ge(Li) detectors permits easy identification on a single gamma spectrum of the gamma\\u000a peaks of239Np formed from238U by activation and those of fission products formed from235U. The ratio of the peak intensities is proportional to the238U\\/235U

M. Mantel; J. Gilat; S. Amiel

1969-01-01

297

Resonant absorption troughs in the gamma-ray spectra of QSO  

NASA Astrophysics Data System (ADS)

We report the very first evidence of the possible detection of ?-ray resonant absorption along the line of sight towards ?-ray bright quasars (QSOs), like 3C 279, 3C 273, PKS 0528+0134, and BL Lacertae. These detections resulted from the analysis of COMPTEL and EGRET data that were collected either during monitoring campaigns of the Virgo and galactic anticenter regions by the Compton Gamma Ray Observatory (CGRO) or during ToO observations of QSOs flares. We discuss three resonant absorption mechanisms that affect the ?-ray spectrum of point-like sources when crossing the surrounding warm and cold absorbers, as well as the potential of this ?-ray photon absorption method to constrain the abundance of the absorber. We detected two absorbers along the line of sight towards ?-ray bright QSOs, one at the QSO rest frame redshift and another at approximately zero redshift. We tentatively identify the latter with an absorber in the Galactic halo, while the former is undoubtedly caused by photon absorption in the host galaxy of the QSO. We discuss the advantages and drawbacks of this method in studies of absorbers in different astrophysical environments and compare this new method to absorber studies at X-ray or other wavelengths. We applied this ?-ray absorption method to identify a few of the EGRET unidentified (EUID) sources as QSOs, and determine their redshifts.

Iyudin, A. F.; Reimer, O.; Burwitz, V.; Greiner, J.; Reimer, A.

2005-06-01

298

Emission from Hot Dust in the Infrared Spectra of Gamma-ray Bright Blazars  

NASA Astrophysics Data System (ADS)

A possible source of ?-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 ?-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 ~1200 K, plus a much weaker optically thin component at ~660 K. The total luminosity of the thermal dust emission is 7.9 ± 0.2 × 1045 erg s-1. If the dust lies in an equatorial torus, the density of infrared photons from the torus is sufficient to explain the ?-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 × 1045 erg s-1. However, in CTA102 the far-infrared spectra are too noisy to detect the 10 ?m silicate feature. Upper limits to the luminosity from thermal emission from dust in PKS 1510-089, and ON231, are 2.3 × 1045, and 6.6 × 1043 erg s-1, respectively. These upper limits do not rule out the possibility of inverse Compton upscattering of infrared photons to ?-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.; Nikutta, Robert; Elitzur, Moshe

2011-05-01

299

STUDY OF THE U\\/Th RATIO IN A THORITE FROM KIVU (BELGIAN CONGO) WITH REGARD TO ITS UTILIZATION IN THE PREPARATION OF THORIUM STANDARDS FOR GAMMA SPECTROMETRY  

Microsoft Academic Search

The uranium and thorium contents of a thorite from Kivu were determined. ; The very low U\\/Th ratio found makes this mineral a good standard for gamma ; spectrometry and fer all other direct radiometric measurements of thorium. The ; mineral was used in the preparation of ThB standards for the determination of the ; absolute age of rocks and

Poulaert

1958-01-01

300

Rapid measurements of soil contamination after the Chernobyl accident in the Federal Republic of Germany by in-situ gamma-ray spectrometry  

Microsoft Academic Search

The method of in situ gamma ray spectrometry for measurements of soil surface contamination is described. The results of nuclide specific measurements of soil contamination in the Federal Republic of Germany after the Chernobyl reactor accident including exposure rate measurements of individual radionuclides are reported. A total of 22 artificial radionuclides could be detected. In the first days after the

I. Winkelmann; S. Weimer; S. Wolff; P. Neumann

1988-01-01

301

Determination of Fluorine in NBS Coal and Coal Fly Ash by Proton Induced Gamma Ray Emission and Spark Source Mass Spectrometry  

Microsoft Academic Search

Fluorine concentrations in US National Bureau of Standards standard reference materials 1632a (coal) and 1633a (coal fly ash) have been determined by proton induced gamma ray emission (PIGME) and spark source mass spectrometry (SSMS) using the method of standard additions. Good agreement was obtained between the two techniques with no significant bias. The mean values for 1632a and 1633a were

E. Clayton; L. S. Dale

1985-01-01

302

Very High Lorentz Factor Fireballs and Gamma-Ray Burst Spectra  

NASA Astrophysics Data System (ADS)

Collisionless entrainment of the surrounding matter imports the relativistic baryon component in the Gamma-Ray Burst (GRB) fireball frame. We show that half the fireball energy can be transferred from radiation to the comoving hot motions of baryons under the photosphere. The yet baryon-poor fireball can reexpand to a very high Lorentz factor (VHLF) ? ˜ 10^3-10^6 by its own relativistic collisionless pressure beyond the photosphere (so-called collisionless bulk acceleration), leading to internal and external shocks. A simple synchrotron emission from the VHLF internal shocks produces (i) the extra power-law spectral component with variability observed in the Fermi GeV bursts, up to the TeV range for the future Cherenkov Telescope Array (CTA), (ii) the GeV onset delay with a weak luminosity dependence t_{delay} ˜ L^{-1/5}, and (iii) the spectral break of GRB 090926 by the synchrotron cooling break or the maximum synchrotron cutoff limited by the dynami cal time, not by the e^{±} creation cutoff. The relativistic baryon component could also heat the photospheric thermal photons into the main GRB Band spectrum via pp, p? (Bethe-Heitler and photomeson), and Coulomb thermalization processes. In this hot photosphere-internal-external shock model, we can predict the anticorrelation of ˜TeV neutrinos and GeV ?-rays, which may be detectable using IceCube. The spectral peak and luminosity (Yonetoku) relation is also reproduced if the progenitor stars are nearly identical. We also discuss the steep/shallow decay of early X-ray afterglows and short GRBs.

Ioka, K.

2010-10-01

303

On Thermalization in Gamma-Ray Burst Jets and the Peak Energies of Photospheric Spectra  

NASA Astrophysics Data System (ADS)

The low-energy spectral slopes of the prompt emission of most gamma-ray bursts (GRBs) are difficult to reconcile with radiatively efficient optically thin emission models irrespective of the radiation mechanism. An alternative is to ascribe the radiation around the spectral peak to a thermalization process occurring well inside the Thomson photosphere. This quasi-thermal spectrum can evolve into the observed non-thermal shape by additional energy release at moderate to small Thomson optical depths, which can readily give rise to the hard spectral tail. The position of the spectral peak is determined by the temperature and Lorentz factor of the flow in the thermalization zone, where the total number of photons carried by the jet is established. To reach thermalization, dissipation alone is not sufficient and photon generation requires an efficient emission/absorption process in addition to scattering. We perform a systematic study of all relevant photon production mechanisms searching for possible conditions in which thermalization can take place. We find that a significant fraction of the available energy should be dissipated at intermediate radii, ~1010 to a few ×1011 cm, and the flow there should be relatively slow: the bulk Lorentz factor could not exceed a few tens for all but the most luminous bursts with the highest E pk values. The least restrictive constraint for successful thermalization, ? <~ 20, is obtained if synchrotron emission acts as the photon source. This requires, however, a non-thermal acceleration deep below the Thomson photosphere transferring a significant fraction of the flow energy to relativistic electrons with Lorentz factors between 10 and 100. Other processes require bulk flow Lorentz factors of order of a few for typical bursts. We examine the implications of these results to different GRB photospheric emission models.

Vurm, Indrek; Lyubarsky, Yuri; Piran, Tsvi

2013-02-01

304

Accurate computation of coincidence summing corrections in low level gamma-ray spectrometry  

Microsoft Academic Search

The GESPECOR (Germanium Spectrometry Correction factors) software, previously developed for computing the self-attenuation and coincidence summing corrections, was applied to the computation of the coincidence summing correction factors for a well-type and two coaxial HPGe detectors. Cylindrical samples as well as Marinelli beaker samples were considered. The computed values are in good agreement with carefully measured values. A detailed study

Octavian Sima; Dirk Arnold

2000-01-01

305

Emission from Hot Dust in the Infrared Spectra of Gamma-ray Bright Blazar  

NASA Astrophysics Data System (ADS)

A possible source of ?-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 dust in the infrared spectra of four ?-ray bright blazars, the quasars 4C21.35, CTA102, and PKS 1510-089, and the BL Lacertae object ON231. The spectral energy distribution (SED) of the quasar 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 1200 K, plus a much weaker optically thin component at 660 K. The total luminosity of the thermal dust emission is 7.9(2)E+45 erg/s . If the dust lies in an equatorial torus, the density of IR photons from the torus is sufficient to explain the ?-ray flux from 4C21.35 as long as the scattering occurs within a few parsecs of the central engine. Upper limits to the luminosity from thermal emission from dust in CTA102, PKS 1510-089, and ON231, are 1.1E+46 , 2.3E+45 , and 6.6E+43 erg/s , respectively. The covering factor of the hot dust in 4C 21.35, 32%, is similar to non-blazar quasars, however 4C 21.35 is deficient in cooler dust. This could be the result of either ultraviolet emission from the jet heating the outer portions of the dust torus.

Malmrose, Michael; Marscher, A. P.; Jorstad, S. G.; Nikutta, R.; Elitzur, M.

2011-01-01

306

A new low-level gamma-ray spectrometry system for environmental radioactivity at the underground laboratory Felsenkeller.  

PubMed

A low-level gamma-ray spectrometry system, based on an HPGe-detector with 92% relative efficiency recently installed in the underground laboratory Felsenkeller at 110 m water equivalent (w.e.) depth, is described. The integral background count rate normalised to the Ge-crystal mass in the energy range from 40 keV until 2.7 MeV of 0.034 s(-1)kg(-1) has been achieved by careful material selection of the detector construction material, a graded shielding construction and effective radon suppression. The detector is highly suitable for the effective surveillance of water for human consumption with decision thresholds for (226)Ra and (228)Ra in the order of some mBq L(-1). PMID:19246204

Köhler, M; Degering, D; Laubenstein, M; Quirin, P; Lampert, M-O; Hult, M; Arnold, D; Neumaier, S; Reyss, J-L

2009-01-23

307

[Radioactive cesium analysis in radiation-tainted beef by gamma-ray spectrometry with germanium semiconductor detector].  

PubMed

The detection limit and precision of radioactive cesium measurement in beef by gamma-ray spectrometry with a germanium semiconductor detector were evaluated. Measurement for 2,000 seconds using a U-8 container (100 mL) provided a detection limit of radioactive cesium (the sum of 134Cs and 137Cs) of around 20 Bq/kg. The 99% confidence interval of the measurement of provisional maximum residue limit level (491 Bq/kg) samples ranged from 447 to 535 Bq/kg. Beef is heterogeneous, containing muscle and complex fat layers. Depending on the sampled parts, the measurement value is variable. It was found that radioactive cesium content of the muscle layer was clearly different from that of fat, and slight differences were observed among parts of the sample (SD=16.9 Bq/kg), even though the same region (neck block) of beef sample was analyzed. PMID:23132357

Minatani, Tomiaki; Nagai, Hiroyuki; Nakamura, Masashi; Otsuka, Kimihito; Sakai, Yoshimichi

2012-01-01

308

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

309

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

310

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

311

High resolution gamma-ray spectrometry of culverts containing transuranic waste at the Savannah River Site  

SciTech Connect

A number of concrete culverts used to retrievably store drummed, dry, radioactive waste at the Savannah River Site (SRS), were suspected of containing ambiguous quantities of transuranic (TRU) nuclides. These culverts were assayed in place for Pu-239 content using thermal and fast neutron counting techniques. High resolution gamma-ray spectroscopy on 17 culverts, having neutron emission rates several times higher than expected, showed characteristic gamma-ray signatures of neutron emitters other than Pu-239 (e.g., Pu-238, Pu/Be, or Am/Be neutron sources). This study confirmed the Pu-239 content of the culverts with anomalous neutron rates and established limits on the Pu-239 mass in each of the 17 suspect culverts by in-field, non-intrusive gamma-ray measurements.

Hofstetter, K.J.; Sigg, R.

1990-12-31

312

High resolution gamma-ray spectrometry of culverts containing transuranic waste at the Savannah River Site  

SciTech Connect

A number of concrete culverts used to retrievably store drummed, dry, radioactive waste at the Savannah River Site (SRS), were suspected of containing ambiguous quantities of transuranic (TRU) nuclides. These culverts were assayed in place for Pu-239 content using thermal and fast neutron counting techniques. High resolution gamma-ray spectroscopy on 17 culverts, having neutron emission rates several times higher than expected, showed characteristic gamma-ray signatures of neutron emitters other than Pu-239 (e.g., Pu-238, Pu/Be, or Am/Be neutron sources). This study confirmed the Pu-239 content of the culverts with anomalous neutron rates and established limits on the Pu-239 mass in each of the 17 suspect culverts by in-field, non-intrusive gamma-ray measurements.

Hofstetter, K.J.; Sigg, R.

1990-01-01

313

Variety identification of wheat using mass spectrometry with neural networks and the influence of mass spectra processing prior to neural network analysis.  

PubMed

The performance of matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry with neural networks in wheat variety classification is further evaluated.1 Two principal issues were studied: (a) the number of varieties that could be classified correctly; and (b) various means of pre-processing mass spectrometric data. The number of wheat varieties tested was increased from 10 to 30. The main pre-processing method investigated was based on Gaussian smoothing of the spectra, but other methods based on normalisation procedures and multiplicative scatter correction of data were also used. With the final method, it was possible to classify 30 wheat varieties with 87% correctly classified mass spectra and a correlation coefficient of 0.90. PMID:12112276

Sørensen, Helle Aagaard; Sperotto, Maria Maddalena; Petersen, Marianne; Ke?mir, Can; Radzikowski, Louise; Jacobsen, Susanne; Søndergaard, Ib

2002-01-01

314

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

315

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

2010-07-27

316

DETERMINATION OF AIRBORNE FISSION PRODUCT RADIOACTIVITY USING GAMMA-RAY SPECTROMETRY  

Microsoft Academic Search

A method for the rapid determination of the radon and thoron daughter ; content of an air filter shortly after removal from the pump is described. It ; utilizes gamma -ray measurements in a portion of the energy spectrum in which ; the spectral shape does not change with time. Afterwards, the contribution to ; the net counting-rate over a

P. F. Gustafson; S. S. Brar; U. C. Mishra

1962-01-01

317

Elemental analysis of a comet nucleus by passive gamma ray spectrometry from a penetrator  

Microsoft Academic Search

The Comet Rendezvous Asteroid Flyby (CRAF) spacecraft, to be launched in 1991, was designed to study the physical and chemical properties of cometary and asteroid bodies. It is proposed that these properties can be determined by utilizing a penetrator experiment delivery system aboard the CRAF, which would deliver a passive gamma ray spectrometer to the comet and determine the composition

Larry G. Evans; Jacob I. Trombka; William V. Boynton

1986-01-01

318

High sensitivity gamma-ray spectrometry: state of the art and trial application of factor analysis  

Microsoft Academic Search

The remote sensing of terrestrial gamma rays has application in geologic mapping, mineral exploration, reactor site monitoring, location of lost radioactive sources, measurement of the water equivalence of snow, and soil mapping. Although the state of the art is quite good, there is a need to reexamine the use of detectors other than thallium activated sodium iodide detectors (e.g., plastic

Joseph S. Duval

1977-01-01

319

Determination of Radionuclides in Drinking Water by gamma Spectrometry: An Interlaboratory Collaborative Study.  

National Technical Information Service (NTIS)

Four reference samples, containing three or all four gamma emitters, exp 60 Co, exp 106 Ru, exp 134 Cs, and exp 137 Cs, from 6 to 400 pCi/L, were prepared and analytical results from 32 participating laboratories evaluated. Coefficients of variation for r...

V. R. Casella C. T. Bishop

1982-01-01

320

GAMMA SPECTROMETRY OF ARTIFICIAL RADIONUCLIDES COLLECTED BY FILTRATION OF THE AIR AT GROUND LEVEL  

Microsoft Academic Search

The radioisotopes in the atmosphere were filtered and the gamma activity ; was counted from March 9 to April 24, 1959, in Naples. The results showed that ; the reciprocal of the activity approximates a straight line. It was deduced that ; the artificial activity originated from a single event about 40 days before the ; collection. The energy interval

G. Aliverti; F. Demichelis; G. Lovera

1959-01-01

321

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

322

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

2012-08-27

323

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

SciTech Connect

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

Ruhter, W.D.

1984-05-01

324

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

325

Verification of the Pu content, isotopic composition and age of plutonium in Pu--Be neutron sources by gamma-spectrometry  

Microsoft Academic Search

A non-destructive, gamma-spectrometric method for verifying the plutonium content of Pu-Be neutron sources has been developed. It is also shown that the isotopic composition and the age of plutonium (Pu) can be determined in the intensive neutron field of these sources by the ``Multi-Group Analysis'' method. Gamma spectra were taken in the far-field of the sample, which was assumed to

Cong Tam Nguyen

2006-01-01

326

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

327

Software ASPRO-NUC: Gamma-ray spectrometry, routine NAA, isotope identification and data management  

Microsoft Academic Search

The software ASPRO-NUC is based on new improved algorithms suggested and tested in the laboratory and intended for routine analysis. The package consists of the program ASPRO for gammaray spectra processing (peak search, multiplets deconvolution by means of method of moments, computation of correction coefficient for geometry and material of radioactive source), a program for isotope identification and a program

V. P. Kolotov; V. V. Atrashkevich

1995-01-01

328

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

NASA Astrophysics Data System (ADS)

Undoped and CuO-doped lithium phosphate, lead phosphate and zinc phosphate glasses were prepared. UV-visible and infrared absorption spectra of the prepared samples were measured before and after successive gamma irradiation. Experimental optical spectra of the undoped samples reveal strong UV absorption bands, which are attributed to the presence of trace iron impurities in both the lithium and zinc phosphate glasses while the lead phosphate glass exhibits broad UV bands due to combined absorption of trace iron impurities and divalent lead ions. The CuO-doped glasses reveal an extra broad visible band due to Cu2+ ions in octahedral coordination. The effects of gamma irradiation have been analyzed for both the sharing of all constituent components including trace iron impurities. Infrared absorption spectra of the prepared samples were investigated by the KBr disk technique. The FTIR spectra reveal main characteristic absorption bands due to different phosphate groups. The IR spectra are observed to be slightly affected by the increase of CuO in the doping level (0.2-3%) indicating the stability of the main network units.

Elbatal, H. A.; Abdelghany, A. M.; Elbatal, F. H.; Elbadry, Kh. M.; Moustaffa, F. A.

2011-10-01

329

Practical applicability of field gamma-ray scintillation spectrometry in geophysical surveys  

PubMed

We discuss the problems and calibration procedures for a portable gamma-ray scintillation spectrometer for determinations of potassium, uranium and thorium concentration in rocks. Particular emphasis was given to the evaluation of the background radiation. The apparatus was tested in the field at two selected areas in NW Italy. We found appropriate sites which could be used as reference targets to frequently check the gamma-ray equipment. An area formed by serpentinitic rocks showed such a low measured radioactivity that it could be used as a reference for the local background effect. An anomalously high uranium amount against negligible potassium and thorium concentrations were found in outcrops of dolomitic rocks, which can be used to detect possible changes in the instrument calibration constants. PMID:10879864

Chiozzi; Pasquale; Verdoya; De Felice P

2000-07-01

330

A deviation display method for visualising data in mobile gamma-ray spectrometry.  

PubMed

A real time visualisation method, to be used in mobile gamma-spectrometric search operations using standard detector systems is presented. The new method, called deviation display, uses a modified waterfall display to present relative changes in spectral data over energy and time. Using unshielded (137)Cs and (241)Am point sources and different natural background environments, the behaviour of the deviation displays is demonstrated and analysed for two standard detector types (NaI(Tl) and HPGe). The deviation display enhances positive significant changes while suppressing the natural background fluctuations. After an initialization time of about 10min this technique leads to a homogeneous display dominated by the background colour, where even small changes in spectral data are easy to discover. As this paper shows, the deviation display method works well for all tested gamma energies and natural background radiation levels and with both tested detector systems. PMID:20456962

Kock, Peder; Finck, Robert R; Nilsson, Jonas M C; Ostlund, Karl; Samuelsson, Christer

2010-04-24

331

On-line analysis of coal by neutron induced gamma spectrometry  

Microsoft Academic Search

Thermal neutron prompt gamma activation analysis (PGNAA) has proven to be a useful tool for the multi-elemental characterization\\u000a of coal. The use of isotopic neutron sources allows the construction of relatively small irradiation facilities for the on-line\\u000a analysis of large volume samples. As a first step to an on-line analysis system for process control in a coal blending plant\\u000a we

H. R. Wilde; W. Herzog

1982-01-01

332

Spectrometry of a 60Co Gamma-Ray Beam Used for Instrument Calibration  

Microsoft Academic Search

Measurements were made of the spectrum of one of the collimated 60Co gamma-ray beams employed in the instrument-calibration program of the National Bureau of Standards. The high-activity calibration-source capsule was replaced by one of low activity and identical geometry. The contributions to the spectrum by the scatter from the low-activity replacement source, the housing, and the collimation system were isolated

M Ehrlich; S M Seltzer; M J Bielefeld; J I Trombka

1976-01-01

333

Multielement analysis of major and minor elements by thermal neutron induced capture gamma-ray spectrometry  

Microsoft Academic Search

The utility of prompt gamma-rays from thermal neutron capture for the measurement of nine elements (Si, Al, Fe, Na, K, Ca,\\u000a Ti, Mg and P) in major and minor abundance has been investigated. National Bureau of Standards (NBS) and United States Geological\\u000a Survey (USGS) standards were used to demonstrate generally good agreement between experimental measurements and certified\\u000a values. Usually accuracies

E. S. Gladney; D. B. Curtis; E. T. Jurney

1978-01-01

334

Accurate computation of coincidence summing corrections in low level gamma-ray spectrometry  

PubMed

The GESPECOR (Germanium Spectrometry Correction factors) software, previously developed for computing the self-attenuation and coincidence summing corrections, was applied to the computation of the coincidence summing correction factors for a well-type and two coaxial HPGe detectors. Cylindrical samples as well as Marinelli beaker samples were considered. The computed values are in good agreement with carefully measured values. A detailed study of the uncertainties assigned to the results was carried out. The analysis shows that the procedures used in GESPECOR are reliable and provide results with a well defined accuracy. PMID:10879837

Sima; Arnold

2000-07-01

335

Measurement of 14 MeV neutron-induced prompt gamma-ray spectra from 15 elements found in cargo containers  

Microsoft Academic Search

Within the EURopean Illicit TRAfficking Countermeasures Kit (EURITRACK) project, the gamma-ray spectra produced in a series of materials by 14-MeV tagged-neutron beams have been collected in the inspection portal equipped with large volume NaI(Tl) detectors, in order to build a database of signatures for various elements: C, N, O, Na, Al, Si, Cl, K, Ca, Cr, Fe, Ni, Cu, Zn,

B. Perot; C. Carasco; S. Bernard; A. Mariani; J.-L. Szabo; G. Sannie; V. Valkovic; D. Sudac; G. Viesti; M. Lunardon; C. Botosso; G. Nebbia; S. Pesente; S. Moretto; A. Zenoni; A. Donzella; M. Moszynski; M. Gierlik; W. Klamra; P. Le Tourneur; M. Lhuissier; A. Colonna; C. Tintori; P. Peerani; V. Sequeira; M. Salvato

2008-01-01

336

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

337

Two-Body Effective-Mass Spectra in the Products of the Reaction gamma+p-->p+pi++pi- and the sigma Resonance  

Microsoft Academic Search

By means of spark chambers and counters we measured the (pi+, pi-) and (pi+\\/-, p) invariant-mass spectra obtained from the products of the reaction gamma+p-->p+pi++pi-. They are in disagreement with the Cutkosky-Zachariasen model which takes into account the effect of the 32, 32 nucleon isobar. To fit our data we introduce a pi-pi final-state enhancement factor with resonant behavior. The

R. del Fabbro; M. de Pretis; R. Jones; G. Marini; A. Odian; G. Stoppini; L. Tau

1965-01-01

338

DERIVATION OF A RELATION FOR THE STEEPENING OF TeV-SELECTED BLAZAR {gamma}-RAY SPECTRA WITH ENERGY AND REDSHIFT  

SciTech Connect

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 spectral energy distribution of TeV-selected BL Lac objects, 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, Floyd William [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Scully, Sean T. [Department of Physics, James Madison University, Harrisonburg, VA 22807 (United States)], E-mail: Floyd.W.Stecker@nasa.gov, E-mail: scullyst@jmu.edu

2010-02-01

339

Optimization of the gamma spectrometry system at SAL with the use of large NaI(Tl) annulus in the anticoincidence mode for compton scattered radiation suppression.  

National Technical Information Service (NTIS)

A gamma-ray spectrometer designed for the simultaneous acquisition of normal, coincidence and anticoincidence spectra was extensively tested. The spectrometer consists of 3 detectors: a HPGe coaxial of 42% efficiency, NaI(Tl) annulus 254 mm length and 254...

J. Kierzek J. Parus

1997-01-01

340

226Ra, 232Th and 40K analysis in soil samples from some areas of Punjab and Himachal Pradesh, India using gamma ray spectrometry  

Microsoft Academic Search

The activity concentrations and the gamma-absorbed dose rates of the terrestrial naturally occurring radio nuclides viz. 226Ra, 232Th and 40K were determined in soil samples collected from some areas of Punjab and Himachal Pradesh, using gamma ray spectrometry. The soil activity ranges from 18.22 to 90.30Bqkg-1 for 226Ra, 34.80 to 124.68Bqkg-1 for 232Th and 80.42 to 181.41Bqkg-1 for 40K with

Surinder Singh; Asha Rani; Rakesh Kumar Mahajan

2005-01-01

341

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

342

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

PubMed

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

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

2013-02-20

343

Intercomparison of methods for coincidence summing corrections in gamma-ray spectrometry.  

PubMed

A comparison of the coincidence summing correction methods is presented. Since there are several ways for computing these corrections, each method has advantages and drawbacks that could be compared. This part of the comparison was restricted to point sources. The same experimental spectra, decay scheme and photon emission intensities were used by all the participants. The results were expressed as coincidence summing correction factors for several energies of (152)Eu and (134)Cs, and three source-to-detector distances. They are presented and discussed. PMID:20117939

Lépy, M-C; Altzitzoglou, T; Anagnostakis, M J; Arnold, D; Capogni, M; Ceccatelli, A; De Felice, P; Dersch, R; Dryak, P; Fazio, A; Ferreux, L; Guardati, M; Han, J B; Hurtado, S; Karfopoulos, K L; Klemola, S; Kovar, P; Lee, K B; Ocone, R; Ott, O; Sima, O; Sudar, S; Svec, A; Tao, Chau Van; Thanh, Tran Thien; Vidmar, T

2010-01-13

344

Measurement of Absolute Fission Yields in the Fast Neutron-Induced Fission of Actinides: {sup 238}U, {sup 237}Np, {sup 238}Pu, {sup 240}Pu, {sup 243}Am, and {sup 244}Cm by Track-Etch-cum-Gamma Spectrometry  

SciTech Connect

The absolute fission yields of 46 fission products in {sup 238}U (99.9997 at.%), 46 fission products in {sup 237}Np, 27 fission products in {sup 238}Pu (99.21 at.%), 30 fission products in {sup 240}Pu (99.48 at.%), 30 fission products in {sup 243}Am (99.998 at.%), and 32 fission products in {sup 244}Cm (99.43 at.%) induced by fast neutrons were determined using a fission track-etch-cum-gamma spectrometric technique. In the case of highly alpha-active and sparingly available actinides - e.g., {sup 238}Pu, {sup 240}Pu, {sup 243}Am, and {sup 244}Cm - a novel recoil catcher technique to collect the fission products on a Lexan polycarbonate foil followed by gamma-ray spectrometry was developed during the course of this work. This completely removed interferences from (a) gamma rays of daughter products in secular equilibrium with the target nuclide (e.g., {sup 243}Am-{sup 239}Np), (b) activation products of the catcher foil [e.g., {sup 24}Na from Al(n,{alpha})], and (c) activation products of the target [e.g., {sup 238}Np from {sup 237}Np(n,{gamma}) and {sup 239}Np from {sup 238}U(n,{gamma})] reactions, making the gamma spectrometric analysis very simple and accurate. The high-yield asymmetric fission products were analyzed by direct gamma spectrometry, whereas the low-yield symmetric products (e.g., Ag, Cd, and Sb) as well as some of the asymmetric fission products (e.g., Br) and rare earths (in the case of {sup 238}U and {sup 237}Np) were radiochemically separated and then analyzed by gamma-ray spectrometry. The neutron spectra in the irradiation positions of the reactors were measured and delineated in the thermal to 10-MeV region using threshold activation detectors. The present data were compared with the ENDF/VI and UKFY2 evaluated data files. From the measured cumulative yields, the mass-chain yields have been deduced using charge distribution systematics. The mass yields, along with similar data for other fast neutron-induced fissioning systems, show several important features:1. Fine structure in the interval of five mass units in even-Z fissioning systems due to odd-even effects. The fine structure decreases from lighter to heavier even-Z actinides, in accordance with their odd-even effect.2. Higher yields in the mass regions 133 to 135, 138 to 140, and 143 to 145 and their complementary mass regions, depending on the mass of the fissioning systems due to the presence of 82n-66n, 86n-62n, and 88n-56n shells.3. For odd-Z fissioning systems having no odd-even effect, the fine structure is very feeble and is due only to shell effects.4. Unusually high yields observed in the mass region 133 to 139 in the fissioning system {sup 239}U* as compared to other U isotopes are explained on the basis of a higher neutron-to-proton ratio (N/Z) of {sup 238}U compared to lower-mass uranium isotopes. The {nu}-bar, full-width at tenth-maximum, and A{sub L}-bar increase with increasing mass of the fissioning systems, whereas A{sub H}-bar of {approx}139 {+-} 1 remains constant throughout due to the strong preference for the formation of the deformed 88n shell, which is also favorable from the N/Z point of view.

Iyer, R.H.; Naik, H.; Pandey, A.K.; Kalsi, P.C.; Singh, R.J.; Ramaswami, A.; Nair, A.G.C. [Bhaha Atomic Research Centre (India)

2000-07-15

345

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

346

Optimized background reduction in low-level gamma-ray spectrometry at a surface laboratory.  

PubMed

The background of a coaxial Ge detector placed at a surface laboratory has been reduced by means of a background reduction setup consisting of a passive shield of low-activity lead, a simple radon suppression system and an active shield with a plastic scintillation plate. In particular, we have devoted our efforts to in-depth optimization of each parameter associated with different anticoincidence setups and to their subsequent intercomparison. The overall performance of the active shield was improved by using the optimum time parameters for each setup. The final objective is to decrease the cosmic-ray background and, by this way, to reduce the detection limits of gamma-ray spectrometers at conventional laboratories, and consequently make them competitive for different measurements like (210)Pb dating. PMID:16530418

Hurtado, S; García-León, M; García-Tenorio, R

2006-03-10

347

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

SciTech Connect

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

W. H. Zhang; A. Chatt

2000-06-04

348

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

349

Monitoring of submarine groundwater discharge along the Donnalucata coast in the south-eastern Sicily using underwater gamma-ray spectrometry  

Microsoft Academic Search

A novel technique for monitoring of submarine groundwater discharge (SGD) in coastal zones based on an in situ underwater gamma-ray spectrometry of radon-decay products is described. Several sites were visited during the IAEA’2002 expedition offshore Donnalucata in the south-eastern Sicily. Continuous monitoring of 222Rn in the beach spring at Donnalucata has shown variable 222Rn activity concentrations in groundwater (from 12

Pavel P. Povinec; Jean-Francois Comanducci; Isabelle Levy-Palomo; Benjamino Oregioni

2006-01-01

350

Concentrations and their ratio of 222Rn decay products in rainwater measured by gamma-ray spectrometry using a low-background Ge detector  

Microsoft Academic Search

The concentrations and the concentration ratios of individual short-lived 222Rn decay products (214Pb and 214Bi) in rainwater were measured at Kumatori village (34.39°N, 135.35°E, approximately 70m above sea level) in Osaka, Japan, by gamma-ray spectrometry using a low-background Ge detector. The dependence of the time variations of the concentrations and their ratios on rainfall rate was investigated. It was observed

Masanori Takeyasu; Takao Iida; Tadashi Tsujimoto; Keizo Yamasaki; Yoshihiro Ogawa

2006-01-01

351

Progressive drowning of carbonate platform in the Moravo-Silesian Basin (Czech Republic) before the Frasnian\\/Famennian event: facies, compositional variations and gamma-ray spectrometry  

Microsoft Academic Search

The Moravo-Silesian Basin (MSB; eastern Czech Republic and southern Poland) hosted an extensive shallow-water carbonate platform\\u000a in the Middle Devonian to Frasnian interval. The platform drowned in a stepwise fashion from the Palmatolepis hassi to the Pa. linguiformis zone. Three types of drowning successions were revealed from conodont biostratigraphy, facies, microfacies and gamma-ray\\u000a spectrometry data: (A) drowning to periplatform turbidite

Ond?ej Bábek; TomᚠP?ikryl; Jind?ich Hladil

2007-01-01

352

Determination of Spatial Distribution Patterns of Clay and Plant Available Potassium Contents in Surface Soils at the Farm Scale using High Resolution Gamma Ray Spectrometry  

Microsoft Academic Search

Variation in dryland crop yield is often related to underlying soil properties such as water availability and soil fertility.\\u000a There are often significant difficulties in adequately defining the spatial distribution of such properties at the farm scale.\\u000a Gamma ray spectrometry (radiometrics) is a relatively new soil sensing technique that can potentially address this by improving\\u000a the mapping of soil texture

Gabriella Pracilio; Matthew L. Adams; Keith R. J. Smettem; Richard J. Harper

2006-01-01

353

Assessment of natural and anthropogenic radioactivity levels in rocks and soils in the environs of Swieradow Zdroj in Sudetes, Poland, by in situ gamma-ray spectrometry  

Microsoft Academic Search

The natural radioactivity of 40K, 208Ti, 212Pb, 212Bi, 214Pb, 214Bi, 228Ac and the fallout of 137Cs in typical rocks and soils of ?wieradów Zdrój area (Sudetes Mountains, Poland) were measured in situ using a portable gamma-ray spectrometry workstation. The measurement points were chosen for different regional lithology: within hornfelses of the Szklarska Pore?ba schist-belt, quartz rocks, gneisses of the ?wieradów

D. Malczewski; L. Teper; J. Dorda

2004-01-01

354

On the measurement of 40 K in natural and synthetic materials by the method of high-resolution gamma-ray spectrometry  

Microsoft Academic Search

In the measurement of natural occurring radioactive material (NORM) concentrations of 40K, 232Th and 238U are measured by passive gamma ray spectrometry with either HPGe or NaI(Tl) detectors. 40K is measured through its 1460.8keV? line. However, till now it has been ignored that this line is mixed with the 1459.2keV line of 228Ac from the chain of 232Th. A correction

N. Lavi; F. Groppi; Z. B. Alfassi

2004-01-01

355

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

Microsoft Academic Search

Europium doped 6LiI crystals (enriched to 96%6 Li) have been studied in neutron detection and gamma-ray spectrometry. Two crystals, 50 mmtimes5 mm and 30 mmtimes3 mm in size were coupled to a calibrated Photonis XP5200 photomultiplier, were tested. The response of 6LiI(Eu) to neutrons emitted from a paraffin moderated Pu-Be source has been investigated and the thermal neutron peak has

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

2005-01-01

356

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

SciTech Connect

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

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

1997-10-01

357

Non-destructive determination of trace amounts of iodine in biological samples by epithermal neutron activation and Compton suppression gamma-ray spectrometry  

Microsoft Academic Search

In order to investigate the ingestion of iodine by human body and to know its content in organs, instrumental epithermal neutron activation analysis was used in conjunction with Compton suppression gamma-ray spectrometry by measuring the 128I short-lived nuclide. The interferences of 24Na and 38Cl induced from NaCl in a sample were reduced by factors of about 6 and 15 to

Ch. Yonezawa; H. Matsue; M. Yukawa

2003-01-01

358

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

359

LAFARA: a new underground laboratory in the French Pyrénées for ultra low-level gamma-ray spectrometry.  

PubMed

We describe a new underground laboratory, namely LAFARA (for "LAboratoire de mesure des FAibles RAdioactivités"), that was recently created in the French Pyrénées. This laboratory is primarily designed to analyze environmental samples that display low radioactivity levels using gamma-ray spectrometry. Two high-purity germanium detectors were placed under 85 m of rock (ca. 215 m water equivalent) in the tunnel of Ferrières (Ariège, France). The background is thus reduced by a factor of ?20 in comparison to above-ground laboratories. Both detectors are fully equipped so that the samples can be analyzed in an automatic mode without requiring permanent presence of a technician in the laboratory. Auto-samplers (twenty positions) and systems to fill liquid nitrogen automatically provide one month of autonomy to the spectrometers. The LAFARA facility allows us to develop new applications in the field of environmental sciences based on the use of natural radionuclides present at low levels in the environment. As an illustration, we present two of these applications: i) dating of marine sediments using the decay of (226)Ra in sedimentary barite (BaSO(4)), ii) determination of (227)Ac ((231)Pa) activities in marine sediment cores. PMID:23164692

van Beek, P; Souhaut, M; Lansard, B; Bourquin, M; Reyss, J-L; von Ballmoos, P; Jean, P

2012-11-16

360

Radon loss from encapsulated sediments in Ge gamma-ray spectrometry for the annual radiation dose determination in luminescence dating  

NASA Astrophysics Data System (ADS)

In Ge gamma-ray spectrometry for the annual radiation dose determination in the luminescence dating of sediments, the picture of 226Ra enrichment or depletion (in the 238U decay series) obtained via measurement of its 214Pb and 214Bi daughters may be disturbed by the 222Rn-content of the sample being decreased due to manipulations such as drying and pulverizing. Therefore, it is common practice to start the measurement only about 1 month after encapsulating the material, after which the 226Ra(1600 a)- 222Rn(3.82 d) mother-daughter equilibrium is re-established. Evidently, this only holds on condition that no significant escape of Rn occurs out of the sediment after making it up for counting. In order to experimentally investigate this effect, in the present work measurements were carried out with various types of dried and pulverized sediments that were either encapsulated in screw-cap polystyrene vials or in sealed glass containers, or that were mixed with molten wax followed by solidification in a cylindrical geometry. From the results obtained, it could be concluded that preparation and counting of the sediment-wax mixture is the method of choice.

de Corte, F.; Vandenberghe, D.; de Wispelaere, A.; Buylaert, J.-P.; van den Haute, P.

2006-01-01

361

Determination of radium isotopes in environmental samples by gamma spectrometry, liquid scintillation counting and alpha spectrometry: a review of analytical methodology.  

PubMed

Radium (Ra) isotopes are important from the viewpoints of radiation protection and environmental protection. Their high toxicity has stimulated the continuing interest in methodology research for determination of Ra isotopes in various media. In this paper, the three most routinely used analytical techniques for Ra isotope determination in biological and environmental samples, i.e. low-background ?-spectrometry, liquid scintillation counting and ?-spectrometry, were reviewed, with emphasis on new methodological developments in sample preparation, preconcentration, separation, purification, source preparation and measurement techniques. The accuracy, selectivity, traceability, applicability and minimum detectable activity (MDA) of the three techniques were discussed. It was concluded that the MDA (0.1mBqL(-1)) of the ?-spectrometry technique coupled with chemical separation is about two orders of magnitude lower than that of low-background HPGe ?-spectrometry and LSC techniques. Therefore, when maximum sensitivity is required, the ?-spectrometry technique remains the first choice. PMID:22245211

Jia, Guogang; Jia, Jing

2012-01-14

362

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

363

Depleted uranium in Kosovo: results of a survey by gamma spectrometry on soil samples.  

PubMed

The presence of depleted uranium in the soil of former Yugoslavia after the 1999 conflict raised great public concern all over the world. The so-called Balkan-syndrome is often linked with depleted uranium contamination. An excellent compilation of data about DU and its possible impact on health and environment can be found in the 1999 UNEP report and publications from the Swedish Radiation Protection Institute. Unfortunately, very few systematic and reliable data on the possible depleted uranium concentrations were until now available. Some of these rare data are only available on the web, without adequate information about the experimental procedure used. To clarify the situation, a systematic survey was started in the summer of 2000 as a collaborative effort between Ghent University (Physics Laboratory) and the Belgian Ministry of Defense (Medical Service). From 50 sites selected all over Kosovo, 150 soil samples were measured in the laboratory with a high-resolution gamma-spectrometer. Some sites (14) were explicitly selected based on military information on the use of depleted uranium munitions in the vicinity. After careful analysis we can conclude that there is no indication of any depleted uranium contamination on these 50 sites with a minimal detectable activity of 15 Bq; this corresponds approximately to 1 mg depleted uranium in a typical sample (100-150 g). PMID:12240731

Uyttenhove, J; Lemmens, M; Zizi, M

2002-10-01

364

Express: systeme d'aide a l'interpretation des spectres (gamma). (Express: Help system to interpretate gamma-ray spectra).  

National Technical Information Service (NTIS)

Interpreting the results given by a software package for gamma spectrum analysis requires an expert to perform a thorough analysis which can be very long depending on spectrum complexity. The idea of building an expert system to help nuclide identificatio...

D. Soulatges J. Monier T. Pineira I. Solier M. Huver

1993-01-01

365

A GRAPHICAL DETERMINATION OF URANIUM AND THORIUM IN ORES FROM THEIR GAMMA RAY SPECTRA. Research Report R 46  

Microsoft Academic Search

BS>A graphical method is described for calculating the uranium and ; thorium contents of ores. The intersection of straight lines, each relating to a ; selected interval in the gamma-ray spectrum, makes possible a rapid estimate of ; the respective contribution of each series (uranium and thorium) to the total ; gamma activity. The departure from equilibrium in the uranium

Horwood

1959-01-01

366

Applying in-silico retention index and mass spectra matching for identification of unknown metabolites in accurate mass GC-TOF mass spectrometry  

PubMed Central

One of the major obstacles in metabolomics is the identification of unknown metabolites. We tested constraints for re-identifying the correct structures of 29 known metabolite peaks from GCT premier accurate mass chemical ionization GC-TOF mass spectrometry data without any use of mass spectral libraries. Correct elemental formulas were retrieved within the top-3 hits for most molecular ion adducts using the “Seven Golden Rules” algorithm. An average of 514 potential structures per formula was downloaded from the PubChem chemical database and in-silico derivatized using the ChemAxon software package. After chemical curation, Kovats retention indices (RI) were predicted for up to 747 potential structures per formula using the NIST MS group contribution algorithm and corrected for contribution of trimethylsilyl groups using the Fiehnlib RI library. When matching the range of predicted RI values against the experimentally determined peak retention, all but three incorrect formulas were excluded. For all remaining isomeric structures, accurate mass electron ionization spectra were predicted using the MassFrontier software and scored against experimental spectra. Using a mass error window of 10 ppm for fragment ions, 89% of all isomeric structures were removed and the correct structure was reported in 73% within the top-5 hits of the cases.

Kumari, Sangeeta; Stevens, Doug; Kind, Tobias; Denkert, Carsten; Fiehn, Oliver

2011-01-01

367

Laser control of Mossbauer spectra as a way to gamma-ray lasing 1 We dedicate this paper to Marlan Scully, quantum cowboy and our hero in science, who has been teaching us physics for many years. 1  

Microsoft Academic Search

We give a comparative analysis of basic schemes of optical control of Mossbauer spectra providing an elimination of resonant absorption by a gamma-ray nuclear transition and suggest a novel scheme of frequency non-selective optical pumping which turns out to be the most promising for a realization of induced gain in the gamma-ray range.

Roman Kolesov; Yuri Rostovtsev; Olga Kocharovskaya

2000-01-01

368

Resolvin D1, Protectin D1, and Related Docosahexaenoic Acid-Derived Products: Analysis via Electrospray/Low Energy Tandem Mass Spectrometry based on Spectra and Fragmentation Mechanisms  

PubMed Central

Resolvin D1 (RvD1) and Protectin D1 (Neuroprotectin D1, PD1/NPD1) are newly identified anti-inflammatory lipid mediators biosynthesized from docosahexaenoic acid (DHA). In this report, the spectra-structure correlations and fragmentation mechanisms were studied using electrospray low-energy collision-induced dissociation tandem mass spectrometry (MS/MS) for biogenic RvD1 and PD1, as well as mono-hydroxy-DHA and related hydroperoxy-DHA. The loss of H2O and CO2 in the spectra indicates the number of functional group(s). Chain-cut ions are the signature of the positions and numbers of functional groups and double-bonds. The observed chain-cut ion is equivalent to a hypothetical homolytic-segment (cc, cm, mc, or mm) with addition or extraction of up to 2 protons (H). The ?-cleavage ions are equivalent to: [cc + H], with H from the hydroxyl through a ?-ene or ?-ene rearrangement; [cm - 2H], with 2H from hydroxyls of PD1 through a ?-ene rearrangement, or one H from the hydroxyl and the other H from the ?-carbon of mono-HDHA through an ?-H-?-ene rearrangement; [mc – H], with H from hydroxyl through a ?-ene or ?-ene rearrangement, or from the ?-carbon through an ?-H-?-ene rearrangement; or [mm] through charge-direct fragmentations. The ?-ene or ?-ene facilitates the H shift to ? position and ?-cleavage. Deuterium labeling confirmed the assignment of MS/MS ions and the fragmentation mechanisms. Based on the MS/MS spectra and fragmentation mechanisms, we identified RvD1, PD1, and mono-hydroxy-DHA products in human neutrophils and blood, trout head-kidney, and stroke-injury murine brain-tissues.

Hong, Song; Lu, Yan; Yang, Rong; Gotlinger, Katherine H.; Petasis, Nicos P.; Serhan, Charles N.

2009-01-01

369

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

PubMed

Mass peak alignment (ion-wise alignment) has recently become a popular method for unsupervised data analysis in untargeted metabolic profiling. Here we present MSClust-a software tool for analysis GC-MS and LC-MS datasets derived from untargeted profiling. MSClust performs data reduction using unsupervised clustering and extraction of putative metabolite mass spectra from ion-wise chromatographic alignment data. The algorithm is based on the subtractive fuzzy clustering method that allows unsupervised determination of a number of metabolites in a data set and can deal with uncertain memberships of mass peaks in overlapping mass spectra. This approach is based purely on the actual information present in the data and does not require any prior metabolite knowledge. MSClust can be applied for both GC-MS and LC-MS alignment data sets. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11306-011-0368-2) contains supplementary material, which is available to authorized users. PMID:22833709

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

2011-10-15

370

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

Microsoft Academic Search

We have observed atmospheric gamma rays from 30 GeV to 8 TeV, using emulsion chambers at balloon altitudes, accumulating the largest total exposure in this energy range to date, SOmegaT˜6.66m2srday. At very high altitudes, with residual overburden only a few gcm-2, atmospheric gamma rays are mainly produced by a single interaction of primary cosmic rays with overlying atmospheric nuclei. Thus,

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

2006-01-01

371

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

Microsoft Academic Search

We have observed atmospheric gamma rays from 30 GeV to 8 TeV, using emulsion chambers at balloon altitudes, accumulating the largest total exposure in this energy range to date, SÏTâ6.66 m² sr day. At very high altitudes, with residual overburden only a few g cm⁻², atmospheric gamma rays are mainly produced by a single interaction of primary cosmic rays with

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

2006-01-01

372

The Primary Proton Spectrum of 0.4-30TEV Deconvolved from Atmospheric Gamma-Ray Spectra at Balloon Altitudes  

Microsoft Academic Search

We have observed atmospheric gamma-rays for 30GeV to 10TeV for many years with the emulsion chamber at balloon altitudes. Since atmospheric gamma-rays observed at several g\\/cm2 are produced almost by a single interaction of primary protons with atmospheric nuclei, we can deconvlve to the primary proton spectrum, referring to an appropriate hadronic interaction model. The proton spectrum estimated by our

K. Yoshida; Y. Komori; J. Nishimura

2002-01-01

373

Broad-band X-ray/gamma-ray spectra and binary parameters of GX 339-4 and their astrophysical implications  

NASA Astrophysics Data System (ADS)

We present X-ray/gamma-ray spectra of the binary GX 339-4 observed in the hard state simultaneously by Ginga and CGRO OSSE during an outburst in 1991 September. The Ginga X-ray spectra are well represented by a power law with a photon spectral index of Gamma~=1.75 and a Compton reflection component with a fluorescent Fe Kalpha line corresponding to a solid angle of an optically thick, ionized medium of ~0.4x2pi. The OSSE data (>=50 keV) require a sharp high-energy cut-off in the power-law spectrum. The broad-band spectra are very well modelled by repeated Compton scattering in a thermal plasma with an optical depth of tau~1 and kT~=50 keV. We also study the distance to the system and find it to be >~3 kpc, ruling out earlier determinations of ~1 kpc. Using this limit, the observed reddening and the orbital period, we find the allowed range of the mass of the primary is consistent with it being a black hole. We find the data are inconsistent with models of either homogenous or patchy coronae above the surface of an accretion disc. Rather, they are consistent with the presence of an inner hot disc with the viscosity parameter of alpha~1 accreting at a rate close to the maximum set by advection. The hot disc is surrounded by a cold outer disc, which gives rise to the reflection component and a soft X-ray excess, also present in the data. The seed photons for Comptonization are unlikely to be due to thermal synchrotron radiation. Rather, they are supplied by the outer cold disc and/or cold clouds within the hot disc. e^+/- pair production is negligible if electrons are thermal. The hot disc model, for which scaled parameters are independent of the black hole mass, is supported by the similarity of the spectrum of GX 339-4 to those of other black hole binaries and Seyfert 1s. On the other hand, their spectra in the soft gamma-ray regime are significantly harder than those of weakly magnetized neutron stars. Based on this difference, we propose that the presence of broad-band spectra corresponding to thermal Comptonization with kT>~50 keV represents a black hole signature.

Zdziarski, Andrzej A.; Poutanen, Juri; Mikolajewska, Joanna; Gierlinski, Marek; Ebisawa, Ken; Johnson, W. Neil

1998-12-01

374

COMPUTATION OF EARLY-TIME FISSION PRODUCT DOSE-RATE SPECTRA AND GAMMA-RAY AIR ATTENUATION  

Microsoft Academic Search

On the basis of photon spectra measurement for shorttime irradiations of ; U\\/sup 235, fission-product dose-rate spectra are computed for 1.7 to 1550 seconds ; after fission. Airattenuation curves that would result from point-isotropic ; sources having such spectral distributions are then coinputed. The fact that the ; attenuation curves are nearly straight lines when plotted against distance from ;

C. F. Ksanda; E. Lauments

1959-01-01

375

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

376

Photoluminescence spectra of thin films containing CdSe/ZnS quantum dots irradiated by 532-nm laser radiation and gamma-rays  

NASA Astrophysics Data System (ADS)

We have investigated temporal behavior of the photoluminescence (PL) spectra of thin films containing CdSe/ZnS quantum dots irradiated by 532 nm laser radiation and gamma-rays. Under ˜ 100 W/cm^2 laser radiation, the PL intensity (IPL) increases with irradiation time upto about 500s and thereafter declines linearly. The wavelength of the PL emission (?peak) exhibits a blue-shift with exposure time. Upon simultaneous irradiation by 100 W/cm^2 532-nm laser, as well as 0.57 and 1.06 MeV gamma-rays, the temporal behaviors of both IPL and ?peak are significantly different; IPL increases to a saturation level, and the magnitude of the blue-shift in ?peak is reduced. We also present data on the effects of the density of the quantum dots on the temporal behavior of the PL spectra, as well as additional data on samples synthesized with CdSe/ZnS quantum dots embedded in conducting polymer films. We discuss possible mechanisms underlying our observations.

Sharma, Suresh; Murphree, Jay; Chakraborty, Tonmoy; Ross, Ajani; Shive, Cecil

2008-03-01

377

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

378

Determination of gamma-hydroxybutyric acid (GHB) in plasma and urine by headspace solid-phase microextraction and gas chromatography/positive ion chemical ionization mass spectrometry.  

PubMed

A new method for the qualitative and quantitative analysis of gamma-hydroxybutyric acid (GHB) in plasma and urine samples is described. It involves the conversion of GHB to gamma-butyrolactone (GBL), its subsequent headspace solid-phase microextraction (SPME), and detection by gas chromatography/positive ion chemical ionization mass spectrometry (GC/PICI-MS), using D(6)-GBL as internal standard. The assay is linear over a plasma GHB range of 1-100 microg/mL (n = 5, r = 0.999) and a urine GHB range of 5-150 microg/mL (n = 5, r = 0. 998). Relative intra- and inter-assay standard deviations, determined for plasma and urine samples at 5 and 50 microg/mL, are all below 5%. The method is simple, specific and reasonably fast. It may be applied for clinical and forensic toxicology as well as for purposes of therapeutic drug monitoring. PMID:11114057

Frison, G; Tedeschi, L; Maietti, S; Ferrara, S D

2000-01-01

379

A BATSE Earth Occultation Catalog of 0.03-1.8 MEV Gamma-Ray Source Spectra and Light Curves for Phases 1-3 (1991-1994)  

NASA Astrophysics Data System (ADS)

Using the powerful Earth-occultation technique, long-term, nearly continuous monitoring of the entire low-energy gamma-ray sky is now possible with the advent of BATSE, the Burst and Transient Source Experiment on board the Compton Gamma Ray Observatory (CGRO). In this paper, we present a catalog of 34 moderately strong gamma-ray sources measured by BATSE. It consists of 0.03-1.8 MeV photon spectra averaged over weeks and months, and light curves of the 35-200 keV flux, with 1 day resolution, covering the first three phases of the CGRO mission (1991 May through 1994 October). These results have been obtained using the JPL Enhanced BATSE Occultation Package (EBOP) developed under the CGRO Guest Investigator Program. The EBOP concept and approach are also described in some depth. This paper presents highlights extracted from a large EBOP database which has now been archived at the Compton Observatory Science Support Center (COSSC). This database contains a complete record of ~1200 daily source count rates in 14 energy channels along with the corresponding Poisson and systematic errors for 64 sources, including 30 not described here. An interface to XSPEC is included in the archive allowing conversion from count rates to photon fluxes. This paper therefore serves also as a reference and entree into the archive and provides an index and guide for those investigators using the EBOP system and database for their respective scientific investigations.

Ling, J. C.; Wheaton, Wm. A.; Wallyn, P.; Skelton, R. T.; Mahoney, Wm. A.; Radocinski, R. G.; Callas, J. L.; Ling, N. F.; Tumer, E.; Shubert, R.

2000-03-01

380

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

2012-03-02

381

Application of Phase Correction to Improve the Interpretation of Crude Oil Spectra Obtained Using 7 T Fourier Transform Ion Cyclotron Resonance Mass Spectrometry  

NASA Astrophysics Data System (ADS)

In this study, a phase-correction technique was applied to the study of crude oil spectra obtained using a 7 T Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). 7 T FT-ICR MS had not been widely used for oil analysis due to the lower resolving power compared with high field FT-ICR MS. For low field instruments, usage of data that has not been phase-corrected results in an inability to resolve critical mass splits of C3 and SH4 (3.4 mDa), and 13C and CH (4.5 mDa). This results in incorrect assignments of molecular formulae, and discontinuous double bond equivalents (DBE) and carbon number distributions of S1, S2, and hydrocarbon classes are obtained. Application of phase correction to the same data, however, improves the reliability of assignments and produces continuous DBE and carbon number distributions. Therefore, this study clearly demonstrates that phase correction improves data analysis and the reliability of assignments of molecular formulae in crude oil anlayses.

Cho, Yunju; Qi, Yulin; O'Connor, Peter B.; Barrow, Mark P.; Kim, Sunghwan

2013-10-01

382

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

383

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

384

Establishing the existence of harmonically-spaced lines in gamma-ray burst spectra using Bayesian inference  

Microsoft Academic Search

We use a rigorous method derived from Bayesian inference to establish the existence of lines in the spectra of ?-ray bursts. Line detection involves a comparison of nested models. The method amounts to the calculation of the odds O favoring models with lines over models without lines. O is given by the product of the maximum likelihood ratio and a

C. Graziani; D. Q. Lamb; T. J. Loredo; E. E. Fenimore; T. Murakami; A. Yoshida

1993-01-01

385

PCGAP: Application to analyze gamma-ray pulse-height spectra on a personal computer under Windows NT ®  

Microsoft Academic Search

PCGAP is a software code, which was written to provide gamma-ray pulse height spectrum analysis on a personal computer platform.\\u000a The code was specifically developed for Windows NT for either an Intel® or DEC Alpha® based processor. PCGAP includes programs which can be used to control data collection using a Canberra INSPECTOR® multichannel pulse-height analyzer. With suitable spectrum conversion routines

E. W. Killian; L. V. East

1998-01-01

386

Characteristics of high energy interactions I. High energy gamma-ray spectra near the top of the atmosphere  

Microsoft Academic Search

An emulsion chamber was used to study the characteristics of high energy nuclear interactions from the production spectra\\u000a of?-rays. The emulsion chamber, which comprised of two parts, namely the detector and the graphite producer unit, was exposed\\u000a to cosmic rays for about 7 hr at an atmospheric depth of 10 g cm?2 at Hyderabad (geomagnetic latitude 7·6°N). 720 electromagnetic cascades

R Hasan; A K Agrawal; M S Swami

1979-01-01

387

Measurements of keV-Neutron Capture Cross Sections and Capture Gamma-Ray Spectra of Se  

Microsoft Academic Search

The neutron capture cross sections and capture ?-ray spectra of Se were measured in a region from 15 to 100 keV and at around 510 keV. A neutron time-of-flight method was used with a ns-pulsed neutron source based on the Li(p,n) Be reaction and with a large anti-Compton NaI(Tl) ?-ray spectrometer. A pulse-height weighting technique was applied to the observed

So KAMADA; Masayuki IGASHIRA; Tatsuya KATABUCHI; Motoharu MIZUMOTO

2010-01-01

388

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

389

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

390

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

SciTech Connect

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

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

2010-01-01

391

Comparison of optimised germanium gamma spectrometry and multicollector inductively coupled plasma mass spectrometry for the determination of 134Cs, 137Cs and 154Eu single ratios in highly burnt UO2  

NASA Astrophysics Data System (ADS)

Non-destructive and destructive methods have been compared to validate their corresponding assessed accuracies in the measurement of 134Cs/137Cs and 154Eu/137Cs isotopic concentration ratios in four spent UO2 fuel samples with very high (52 and 71 GWd/t) and ultra-high (91 and 126 GWd/t) burnup values, and about 10 (in the first three samples) and 4 years (in the latter sample) cooling time. The non-destructive technique tested was high-resolution gamma spectrometry using a high-purity germanium detector (HPGe) and a special tomographic station for the handling of highly radioactive 400 mm spent fuel segments that included a tungsten collimator, lead filter (to enhance the signal to Compton background ratio and reduce the dead time) and paraffin wax (to reduce neutron damage). The non-destructive determination of these isotopic concentration ratios has been particularly challenging for these segments because of the need to properly derive non-Gaussian gamma-peak areas and subtract the background from perturbing capture gammas produced by the intrinsic high-intensity neutron emissions from the spent fuel. Additionally, the activity distribution within each pin was determined tomographically to correct appropriately for self-attenuation and geometrical effects. The ratios obtained non-destructively showed a 1? statistical error in the range 1.9 2.9%. The destructive technique used was a high-performance liquid chromatographic separation system, combined online to a multicollector inductively coupled plasma mass spectrometer (HPLC-MC-ICP-MS), for the analysis of dissolved fuel solutions. During the mass spectrometric analyses, special care was taken in the optimisation of the chromatographic separation for Eu and the interfering element Gd, as also in the mathematical correction of the 154Gd background from the 154Eu signal. The ratios obtained destructively are considerably more precise (1? statistical error in the range 0.4 0.8% for most of the samples, but up to 2.8% for one sample). The HPGe gamma spectrometry can achieve a high degree of accuracy (agreement with HPLC-MC-ICP-MS within a few percent), only by virtue of the optimised setup, and the refined measurement strategy and data treatment employed.

Caruso, S.; Günther-Leopold, I.; Murphy, M. F.; Jatuff, F.; Chawla, R.

2008-05-01

392

Numerical expressions for the computation of coincidence-summing correction factors in gamma-ray spectrometry with HPGe detectors.  

PubMed

Numerical expressions to compute gamma-gamma and gamma-X(K) coincidence summing corrections were deduced by using a suitable computer program and a matrix representation of a decay scheme. For point sources only full-energy peak and total efficiencies are needed. Alternatively, values of peak-to-total ratio can be introduced. For extended sources, the same expressions can be considered with the introduction of "effective efficiencies". Examples of the use of the expressions for point sources and a particulate filter sample measured with a 60% relative efficiency HPGe detector are reported. PMID:19892555

Rizzo, S; Tomarchio, E

2009-10-22

393

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

394

QUANTITATIVE GAMMA-RAY SPECTROMETRIC ANALYSIS OF NUCLIDE MIXTURES, CONSECUTIVE STANDARD SOURCES NULLIFICATION  

Microsoft Academic Search

Conventional methods for analyzing fission product mixtures are lengthy ; and difficult. Gamma scintillation spectrometry shortens the analysis time and ; gives a visible picture of what is being counted. However, for complex spectra, ; the graphical representation and interpretation of data require tedious plotting ; and data reduction time. In the proposed method a sample of mixed fission ;

1959-01-01

395

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

396

Multiple Group Analysis (MGA): A gamma-ray spectrum analysis code for determining plutonium isotopic abundances  

SciTech Connect

MGA calculates relative isotopic abundances of plutonium and other actinides in a sample. The code performs its analysis using data from a gamma-ray spectrum of the sample taken with a germanium detector. This volume describes the structure of the program and the procedures used for measuring samples and analyzing the spectra. It is assumed that the user is familiar with standard practices and equipment used in gamma-ray spectrometry.

Gunnink, R.; Ruhter, W.D.

1990-09-01

397

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

PubMed

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

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

2012-08-24

398

Identification and quantification of gamma-glutamyl conjugates of biogenic amines in the nervous system of the snail, Helix aspersa, by gas chromatography-negative-ion chemical ionisation mass spectrometry.  

PubMed

The gamma-glutamyl conjugates of p-octopamine and dopamine were identified unambiguously for the first time and quantified in a single cerebral ganglion or pleural plus pedal ganglia of the snail, Helix aspersa, by gas chromatography-negative-ion chemical ionisation mass spectrometry. A new method was used for synthesis of gamma-glutamylamine standards. The concentration of gamma-glutamyltyramine was found to be low in the tissues, therefore it was used as an internal standard. The gamma-glutamylamines were extracted with water and derivatised with pentafluoropropionic anhydride and trifluoroethanol. Under negative-ion chemical ionisation conditions, the trifluoroethyl and pentafluoropropionyl derivatives produced significant ions which were sufficiently abundant to be suitable for selective ion monitoring. The method had a limit of detection of ca. 80 pg of gamma-glutamyl conjugate per tissue and calibration curves were linear over the range examined. PMID:8376522

Zhou, P; Watson, D G; Midgley, J M

1993-07-23

399

Proton-induced prompt gamma-ray spectrometry: A survey of its analytical significance and some applications  

Microsoft Academic Search

A survey was carried out of prompt gamma-rays emitted during bombardment of all stable non-gaseous elements with protons from\\u000a 3.5 to 6.0 MeV. Attainable sensitivities were calculated for the 5 most intense gamma-rays as a function of bombarding energy.\\u000a For most elements maximum sensitivity was attainable with protons between 4 and 5 MeV. Applications of the technique to the\\u000a analysis

D. Gihwala; M. Peisach

1982-01-01

400

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

401

Nondestructive determination of boron and cadmium in environmental materials by thermal neutron-prompt. gamma. -ray spectrometry  

Microsoft Academic Search

Prompt ..gamma.. rays from thermal neutron induced nuclear reactions have been used to measure trace quantities of B and Cd in industrial and standard materials. The technique provides a rapid nondestructive analysis for > 0.05 ..mu..g of B. Repetitive analyses show the method to have a precision of 5%. The presence of large quantities of Na degrades the accuracy and

Ernest S. Gladney; Edward T. Jurney; David B. Curtis

1976-01-01

402

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

SciTech Connect

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

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

1991-11-12

403

Use of airborne gamma-ray spectrometry for environmental assessment of the rehabilitated nabarlek uranium mine, Australia.  

PubMed

This article describes an airborne gamma survey of a 7 x 5 km region around the rehabilitated Nabarlek uranium mine in northern Australia. An unusually tight line spacing (100 m) and low aircraft height (50 m) were used, enabling the survey to distinguish man-made structures such as ponds and accommodation areas, as well as creek lines. Positive correlations between airborne data and ground-based readings enabled an estimation of the average absorbed dose rate arising from terrestrial gamma radiation over large areas of the site to be derived. For the fenced minesite area this estimate was 0.31 micro Gy hr(- 1). The airborne survey data were found to be invaluable in helping to plan further ground-level investigations and showed promise as an assessment tool for rehabilitated minesites. PMID:16649135

Martin, Paul; Tims, Stephen; McGill, Anthony; Ryan, Bruce; Pfitzner, Kirrilly

2006-04-30

404

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

Microsoft Academic Search

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

Miodrag Bolic; Vujo Drndarevic; Wail Gueaieb

2010-01-01

405

Peak efficiency calibration for attenuation corrected cylindrical sources in gamma ray spectrometry by the use of a point source.  

PubMed

A theoretical method of determining the gamma-ray peak efficiency for a cylindrical source, based on a modified expression for point sources is derived. A term for the photon self-attenuation is included in the calculation. The method is valid for any source material as long as the source activity concentration is considered to be homogeneous. Results of this expression are checked against experimental data obtained with (241)Am, (57)Co, (137)Cs, and (60)Co sources. PMID:16854587

Aguiar, Julio C; Galiano, Eduardo; Fernandez, Jorge

2006-07-18

406

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

Microsoft Academic Search

For the determination of airborne radionuclide concentrations in real time, a fixed filter device was constructed which fits directly onto a germanium detector with standard nuclear electronics and a multichannel analyzer buffer connected via a data line to a personal computer for remote control and on-line spectrum evaluation. The on-line gamma-ray spectrometer was applied to the study of radon decay

H. Hiitzl; R. Winkler

1993-01-01

407

Monte Carlo simulation of the self-absorption corrections for natural samples in gamma-ray spectrometry  

Microsoft Academic Search

Gamma-ray self-attenuation corrections in the energy range 60–2000keV were evaluated by means of Monte Carlo calculations for environmental samples in a cylindrical measuring geometry. The dependence of the full-energy peak efficiency on the sample density was obtained for some particular photon energies and, as a result, the corresponding self-attenuation correction factors were obtained. The calculations were performed by assuming that

M. Jurado Vargas; A. Fernández Timón; N. Cornejo D??az; D. Pérez Sánchez

2002-01-01

408

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

Microsoft Academic Search

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,

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

1996-01-01

409

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

410

Reduction in liquid secondary ion mass spectrometry. Comparison of the fission fragment and liquid secondary ion mass spectra of organic dyes  

Microsoft Academic Search

Mass spectral characterlzatlon of the Intact chromophore of organic dyestuffs, frequently prepared as salts, Is relatlvely faclle wlth desorptlon lonlratlon. The mass spectra obtalned, however, may show the presence of chemlcally altered forms of the chromophore. Comparlson of the flsslon fragment (FF) and llquld secondary Ion mass spectra (Ilquld SIMS) of a serles of dyes reveals enhanced (C + 1)'

P. Jane. Gale; Bryan L. Bentz; Brian T. Chait; Frank H. Field; Robert J. Cotter

1986-01-01

411

Intercomparison of methods for coincidence summing corrections in gamma-ray spectrometry--part II (volume sources).  

PubMed

The second part of an intercomparison of the coincidence summing correction methods is presented. This exercise concerned three volume sources, filled with liquid radioactive solution. The same experimental spectra, decay scheme and photon emission intensities were used by all the participants. The results were expressed as coincidence summing corrective factors for several energies of (152)Eu and (134)Cs, and different source-to-detector distances. They are presented and discussed. PMID:22445105

Lépy, M-C; Altzitzoglou, T; Anagnostakis, M J; Capogni, M; Ceccatelli, A; De Felice, P; Djurasevic, M; Dryak, P; Fazio, A; Ferreux, L; Giampaoli, A; Han, J B; Hurtado, S; Kandic, A; Kanisch, G; Karfopoulos, K L; Klemola, S; Kovar, P; Laubenstein, M; Lee, J H; Lee, J M; Lee, K B; Pierre, S; Carvalhal, G; Sima, O; Tao, Chau Van; Thanh, Tran Thien; Vidmar, T; Vukanac, I; Yang, M J

2012-03-13

412

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

Microsoft Academic Search

The analysis of gamma-emitting radionuclides in nature, i.e. Ra, Th, K and Cs, has been carried out in soil samples collected from Peshawar University Campus and surrounding areas using a high purity germanium detector coupled with a computer-based high-resolution multichannel analyser. The activity concentrations in soil ranged from 30.20±0.65 to 61.90±0.95, 50.10±0.54 to 102.80±1.04, 373.60±4.56 to 1082±11.38 and 9.50±0.11 to

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

2012-01-01

413

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

2011-12-16

414

Electron capture negative ion (ECNI) mass spectrometry of complex mixtures of chlorinated decanes and dodecanes: An approach to ECNI mass spectra of chlorinated paraffins in technical mixtures  

Microsoft Academic Search

The electron capture negative ion (ECNI) mass spectra of two complex mixtures of polychlorinated decanes (PCDe) and polychlorinated\\u000a dodecanes (PCDo) are presented. The number of isomers in these mixtures is still high but is drastically reduced in comparison\\u000a to technical products of chlorinated paraffins (CP), due to their fixed chain length. As a result, the mass spectra are simplified\\u000a and

Oliver Froescheis; Karlheinz Ballschmiter

1998-01-01

415

Determination of the Capture to the Fission Cross-Sections Ratio by the Measurements of the Gamma-Rays Coincidence Multiplicity Spectra at Neutron Resonance Absorption by 235U  

Microsoft Academic Search

The capture to the fission cross-sections ratio (alpha value) was investigated by the measurements of gamma-rays time-of-flight spectra from the first to fifteenth multiplicities on the 500 m flight path of the IBR-30 reactor. One has used a 16-sections scintillation detector with NaI(Tl) crystals and two metal samples of 0.00137 and 0.00411 at\\/b thicknesses (the content: 235U :238 U =

Yu. V. Grigoriev; V. V. Sinitsa; Zh. V. Mezentseva; A. B. Popov; Yu. P. Popov; G. Ilchev; H. Faikov-Stanzcyk

2003-01-01

416

An analytical calculation of the peak efficiency for cylindrical sources perpendicular to the detector axis in gamma-ray spectrometry.  

PubMed

An analytical expression for the so-called full-energy peak efficiency epsilon(E) for cylindrical source with perpendicular axis to an HPGe detector is derived, using point-source measurements. The formula covers different measuring distances, matrix compositions, densities and gamma-ray energies; the only assumption is that the radioactivity is homogeneously distributed within the source. The term for the photon self-attenuation is included in the calculation. Measurements were made using three different sized cylindrical sources of 241Am, 57Co, 137Cs, 54Mn, and 60Co with corresponding peaks of 59.5, 122, 662, 835, 1173, and 1332 keV, respectively, and one measurement of radioactive waste drum for 662, 1173, and 1332 keV. PMID:18249126

Aguiar, Julio C

2007-12-23

417

The use of MCNP and gamma spectrometry in supporting the evaluation of NORM in Libyan oil pipeline scale  

NASA Astrophysics Data System (ADS)

The accumulation of scales in production pipes is a common problem in the oil industry, reducing fluid flow and also leading to costly remedies and disposal issues. Typical materials found in such scale are sulphates and carbonates of calcium and barium, or iron sulphide. Radium arising from the uranium/thorium present in oil-bearing rock formations may replace the barium or calcium in these salts to form radium salts. This creates what is known as technologically enhanced naturally occurring radioactive material (TENORM or simply NORM). NORM is a serious environmental and health and safety issue arising from commercial oil and gas extraction operations. Whilst a good deal has been published on the characterisation and measurement of radioactive scales from offshore oil production, little information has been published regarding NORM associated with land-based facilities such as that of the Libyan oil industry. The ongoing investigation described in this paper concerns an assessment of NORM from a number of land based Libyan oil fields. A total of 27 pipe scale samples were collected from eight oil fields, from different locations in Libya. The dose rates, measured using a handheld survey meter positioned on sample surfaces, ranged from 0.1-27.3 ?Sv h-1. In the initial evaluations of the sample activity, use is being made of a portable HPGe based spectrometry system. To comply with the prevailing safety regulations of the University of Surrey, the samples are being counted in their original form, creating a need for correction of non-homogeneous sample geometries. To derive a detection efficiency based on the actual sample geometries, a technique has been developed using a Monte Carlo particle transport code (MCNPX). A preliminary activity determination has been performed using an HPGe portable detector system.

Habib, Ahmed S.; Bradley, D. A.; Regan, P. H.; Shutt, A. L.

2010-07-01

418

Mass spectrometry of the phosphatidyl amino alcohols: detection of molecular species and use of low voltage spectra and metastable scanning in the elucidation of structure  

Microsoft Academic Search

The basic fragmentation mechanisms occurring in the mass spectra of the phosphatidylcholines have been described previously, and evidence was adduced to show that many of the more abundant ions are related by electron im- pact-induced processes. A molecular ion was demonstrated for dioleoyl glycerylphosphorylcholine by accurate mass measurement and by metastable scanning. In the present paper, results are reported which

R. A. Klein

419

Open Mass Spectrometry Search Algorithm  

Microsoft Academic Search

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

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

2004-01-01

420

Evidence for thermal decomposition contributions to the mass spectra of chlorinated phenoxyacid herbicides obtained by particle beam liquid chromatography mass spectrometry  

Microsoft Academic Search

The spectral quality of a group of chlorinated phenoxyacid herbicides has been shown to degrade under certain conditions upon\\u000a introduction into the mass spectrometer by a particle beam interface. Experiments were performed to investigate these changes\\u000a in spectra. Normalized ion chromatograms were generated for the herbicides, and the results showed a broadening of the profiles\\u000a of some ions, indicating a

L. Donnelly Betowski; Chris M. Pace; Mark R. Roby

1992-01-01

421

Average X-Ray/Gamma-Ray Spectra of Seyfert Galaxies From Ginga and OSSE and the Origin of the Cosmic X-Ray Background.  

National Technical Information Service (NTIS)

We have obtained the first average 2-500 keV spectra of Seyfert galaxies, using the data from Ginga and GRO OSSE. Our sample contains 3 classes of objects with markedly different spectra: radio-quiet Seyfert 1s and 2s, and radio-loud Seyfert 1s. The avera...

A. A. Zdziarski C. Done D. Smith K. McNaron-Brown W. N. Johnson

1995-01-01

422

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

423

Determination of the Capture to the Fission Cross-Sections Ratio by the Measurements of the Gamma-Rays Coincidence Multiplicity Spectra at Neutron Resonance Absorption by 235U  

NASA Astrophysics Data System (ADS)

The capture to the fission cross-sections ratio (alpha value) was investigated by the measurements of gamma-rays time-of-flight spectra from the first to fifteenth multiplicities on the 500 m flight path of the IBR-30 reactor. One has used a 16-sections scintillation detector with NaI(Tl) crystals and two metal samples of 0.00137 and 0.00411 at/b thicknesses (the content: 235U :238 U = 90% : 10%.) The multiplicity spectra of coincidence and the alpha values ? = ??/?f were obtained for 212 resolved resonances in the neutron energy region E=19-1260 eV and for energy groups over the range 20-2000 eV. The experimental alpha values were compared with the similar values calculated on a basis of evaluated data from different libraries using the model of neutron cross sections description in multilevel R-matrix approximation.

Grigoriev, Yu. V.; Sinitsa, V. V.; Mezentseva, Zh. V.; Popov, A. B.; Popov, Yu. P.; Ilchev, G.; Faikov-Stanzcyk, H.

2003-06-01

424

Effect of Converted Isometric Transition in (125m)Te on the Emission Spectra of Mossbauer Gamma-Quanta in a Number of Tellurium Compounds.  

National Technical Information Service (NTIS)

New sources for nuclear gamma-resonance experiments with 125Te were tested. Beta-((125m)Te)O3 was found to have a recoilless fraction of gamma-rays double that of Pb((125m)Te) or 125Sb in a Cu-matrix. H6((126m)Te)O6 and Na2H4 ((125m)Te) O6 sources yielded...

V. A. Lebedev R. A. Lebedev A. M. Babeshkin A. N. Nesmeyanov

1972-01-01

425

Dramatic resolution enhancement of gamma-ray spectra acquired with cadmium-zinc-telluride detectors via a patented pulse-shape-analysis methodology  

Microsoft Academic Search

We are developing a technique to correct for the resolution-degrading ballistic deficit in cadmium-zinc-telluride (CZT) gamma-ray detectors using our patent-pending pulse-shape analysis methodology. The pulse-shape-analysis methodology has already been demonstrated by LLNL for application in Compton rejection (technology being licensed) and possible application to gamma-ray imaging with Ge-based systems. If the extension of our technique to CZT detectors is successful,

S. A. Kreek; Y. Darsdenne; Dean Beckedahl; G. J. Schmid; Jerry J. Blair; J. Kammeraad; Allen Friensehner

2000-01-01

426

Free electron laser-Fourier transform ion cyclotron resonance mass spectrometry facility for obtaining infrared multiphoton dissociation spectra of gaseous ions  

SciTech Connect

A Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer has been installed at a free electron laser (FEL) facility to obtain infrared absorption spectra of gas phase ions by infrared multiple photon dissociation (IRMPD). The FEL provides continuously tunable infrared radiation over a broad range of the infrared spectrum, and the FT-ICR mass spectrometer, utilizing a 4.7 Tesla superconducting magnet, permits facile formation, isolation, trapping, and high-mass resolution detection of a wide range of ion classes. A description of the instrumentation and experimental parameters for these experiments is presented along with preliminary IRMPD spectra of the singly-charged chromium-bound dimer of diethyl ether (Cr(C{sub 4}H{sub 10}O){sub 2}{sup +}) and the fluorene molecular ion (C{sub 13}H{sub 10}{sup +}). Also presented is a brief comparison of the fluorene cation spectrum obtained by the FT-ICR-FEL with an earlier spectrum recorded using a quadrupole ion trap (QIT)

Valle, Jose J.; Eyler, John R.; Oomens, Jos; Moore, David T.; Meer, A.F.G. van der; Helden, Gert von; Meijer, Gerard; Hendrickson, Christopher L.; Marshall, Alan G.; Blakney, Gregory T. [Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200 (United States); FOM-Institute for Plasma Physics Rijnhuizen, Edisonbaan 14, NL-3439 MN Nieuwegein (Netherlands); FOM-Institute for Plasma Physics Rijnhuizen, Edisonbaan 14, NL-3439 MN Nieuwegein (Netherlands); Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin (Germany); National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310-4005 (United States); Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306 (United States); National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310-4005 (United States)

2005-02-01

427

Use of a TLD-based multisphere spectrometry system to measure the neutron spectra around a not-self-shielded PET cyclotron: Preliminary results.  

PubMed

In the present work, we utilized the BSS system with TLD-600 and TLD-700 to measure the neutron spectra around the GE-PETtrace 8 cyclotron of the Development Centre of Nuclear Technology (CDTN/CNEN) in Belo Horizonte, Brazil. The cyclotron is capable of accelerating protons up to 16.5 MeV, to production of fluorine-18. Four points inside the bunker of the cyclotron were studied. Two points in front of the primary radiation beam and other two opposed to the primary radiation beam. The measurements were unfolded with the BUMS and the NSDUAZ computer codes. The dosimetric quantities obtained were in agreement with the other published data and were coherent with the expected from theoretical estimates obtained from source term informed by the manufacturer of the cyclotron. PMID:22818173

Guimarães, A M; Lacerda, M A S; Santos, J A L; Maletta, P G M; Rodrigues, S L M; Andrade, R S; Vilela, E C; da Silva, T A

2012-06-09

428

Characterization of in vivo and in vitro metabolites of furanodiene in rats by high performance liquid chromatography-electrospray ionization mass spectrometry and nuclear magnetic resonance spectra.  

PubMed

Furanodiene is an active ingredient of Rhizoma Curcumae, a very famous Traditional Chinese Medicine (TCM) widely used for the treatment of cancer. Although the anti-tumor effect of furanodiene has well been established, its metabolic profile in vivo and in vitro is still unclear. In the present study, the metabolites of furanodiene in rats were studied. After oral administration of furanodiene, the rats' urine, feces and bile were collected and produced seven metabolites by the use of macroporous adsorption resin chromatography, and semi-preparative high performance liquid chromatography. Their structures were identified by mass spectrometry and NMR data including (1)H, (13)C, and two-dimensional NMR data. All of these metabolites were phase I metabolites, with three new compounds including 2?-hydroxyl-aeruginolactone (2), 14-hydroxyl-aeruginolactone (3), 1?,8?-dihydroxyeudesm-4,7(11)-dien-8?,12-olide (4a), and four known compounds, 1?,10?,4?,5?-diepoxy-8?-hydroxy-glechoman-8?,12-olide (1), 1?,8?-dihydroxyeudesm-4(14),7(11)-dien-8?,12-olide (4b), 1?,8?-dihydroxyeudesm-3,7(11)-dien-8?,12-olide (5) and aeruginolactone (6). Interestingly, the metabolite 6 was found to be a primary metabolite in urine, bile and feces. All metabolites were found to be both in urine and bile but only few metabolites except the metabolite 6 presented in feces after oral dose of furanodiene to rats. Furthermore, the metabolic pathways of furanodiene were proposed using an in vitro assay by incubation of furanodiene and its metabolites in vivo with rat liver S9 or liver microsomes. Clearly, aeruginolactone (6) seemed to be a major precursor for other metabolites. PMID:23998967

Chen, Meng; Lou, Yan; Wu, Yaodong; Meng, Zhaoke; Li, Liping; Yu, Lushan; Zeng, Su; Zhou, Hui; Jiang, Huidi

2013-08-17

429

Gamma-Ray Spectra of the Products of Fast Neutron Fission of U235 and U238 at Selected Times after Fission.  

National Technical Information Service (NTIS)

Experimental measurements of the gamma-ray pulse height distributions due to the products of fast-neutron-induced fission of U235 and U238 are presented. The measurements were made at nine selected times after fission from 15 minutes to 3 days. Irradiatio...

L. R. Bunney D. Sam

1966-01-01

430

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

431

SPECTRA AND ANGULAR DISTRIBUTION OF THE SCATTERED GAMMA-RAYS IN IRON ORIGINATING FROM A TWO DIMENSIONAL AND UNIDIRECTIONAL Co⁶° SOURCE  

Microsoft Academic Search

A total-absorption spectrometer with a cylindrical Nal(Tl) crystal was ; used for the measurement of the spectral and angular distribution of gamma -rays ; generated in a Fe barrier layer with thickness of 6 times the mean free path of ; the particles (15.6 cm) under angles of 20, 50, and 70 deg . The highest points ; of the

Larichev

1961-01-01

432

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

433

ANNEX 52 Monte Carlo model of a gamma spectrometry system for in situ assessment of induced activity at fusion reactor components  

Microsoft Academic Search

In this work, a preliminary design of a gamma spectrometer system for in situ radioactivity assay of induced activity at components of a future fusion power plant is presented. The system incorporates a HPGe detector, gamma ray shielding and an adjustable collimator. Monte Carlo code MCNP was used to predict the system response for assaying a wall composed of activated

F. Tzika; I. E. Stamatelatos

434

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

2009-04-02

435

Progress in numerical modelling of the Cl influence on gamma-ray spectra from an n-gamma logging tool, by using the improved ENDF data for radiative capture.  

PubMed

Quality of the numerical modelling (MCNP code) of the spectrometric neutron-gamma benchmark experiment, performed at the Polish Calibration Station BGW in Zielona Gora for quantification of the main rock elements: Si, Ca, Fe and H, is considered. Elemental concentrations obtained from the measurements and simulations, for the rock models with water-filled boreholes, are in good agreement. For chlorine present in the borehole, the quality of the numerical reproducibility of the measured elemental concentrations depends on the cross section library used for the Cl(n,gamma)Cl reaction. The standard evaluated nuclear data library ENDF/B-VI Release 2 supplies imperfect data for photon production from thermal neutron capture in Cl. The improved cross sections for Cl(n,gamma)Cl are included in the ENDF/B-VI Release 8 library. Superiority of this new compilation over the previous one is shown in the paper. The accuracies for the Si, Ca and Fe determination have been improved by about 36%, 19.9% and 21.4%, respectively, when the ENDF/B-VI Release 8 library has been used for Cl. PMID:17011201

Cywicka-Jakiel, Teresa

2006-09-28

436

Gamma II  

NASA Astrophysics Data System (ADS)

GAMMA II is the Guide Star Automatic Measuring MAchine relocated from STScI to the Astronomical Photographic Data Archive (APDA) at the Pisgah Astronomical Research Institute (PARI). GAMMA II is a multi-channel laser-scanning microdensitometer that was used to measure POSS and SERC plates to create the Guide Star Catalog and the Digital Sky Survey. The microdensitometer is designed with submicron accuracy in x and y measurements using a HP 5507 laser interferometer, 15 micron sampling, and the capability to measure plates as large as 0.5-m across. GAMMA II is a vital instrument for the success of digitizing the direct, objective prism, and spectra photographic plate collections in APDA for research. We plan several targeted projects. One is a collaboration with Drs. P.D. Hemenway and R. L. Duncombe who plan to scan 1000 plates of 34 minor planets to identify systematic errors in the Fundamental System of celestial coordinates. Another is a collaboration with Dr. R. Hudec (Astronomical Institute, Academy of Sciences of the Czech Republic) who is working within the Gaia Variability Unit CU7 to digitize objective prism spectra on the Henize plates and Burrell-Schmidt plates located in APDA. These low dispersion spectral plates provide optical counterparts of celestial high-energy sources and cataclysmic variables enabling the simulation of Gaia BP/RP outputs. The astronomical community is invited to explore the more than 140,000 plates from 20 observatories now archived in APDA, and use GAMMA II. The process of relocating GAMMA to APDA, re-commissioning, and starting up the production scan programs will be described. Also, we will present planned research and future upgrades to GAMMA II.

Barker, Thurburn; Castelaz, M.; Cline, J.; Owen, L.; Boehme, J.; Rottler, L.; Whitworth, C.; Clavier, D.

2011-05-01

437

DS02 fluence spectra for neutrons and gamma rays at Hiroshima and Nagasaki with fluence-to-kerma coefficients and transmission factors for sample measurements  

Microsoft Academic Search

Fluence spectra at several ground distances in Hiroshima and Nagasaki are provided along with associated fluence-to-kerma\\u000a coefficients from the Dosimetry System 2002 (DS02). Also included are transmission factors for calculating expected responses\\u000a of in situ sample measurements of neutron activation products such as 32P,36Cl,39Ar,41Ca, 60Co,63Ni,152Eu,  and 154Eu. The free-in-air (FIA) fluences calculated in 2002 are available for 240 angles, 69 energy

Stephen D. Egbert; George D. Kerr; Harry M. Cullings

2007-01-01

438

Distribution of natural and anthropogenic radionuclides in soil and beach sand samples of Kalpakkam (India) using hyper pure germanium (HPGe) gamma ray spectrometry  

Microsoft Academic Search

Pre-operational survey at Kalpakkam coast, indicated elevated gamma background radiation levels in the range of 100–4000nGyh?1 over the large tracts of the coastal sands due to the presence of pockets of monazite mineral in beach sands. In view of the prevalence of monazite, a systematic gamma spectrometric study of distribution of natural radionuclides in soil and beach sand samples collected

V Kannan; M. P Rajan; M. A. R Iyengar; R Ramesh

2002-01-01

439

Coincidence method for the analysis of minor elements in steel by deuteron-induced prompt \\/gamma-ray spectrometry (d-PIGE)  

Microsoft Academic Search

The sensitivities of minor elements analysis in a standard steel sample irradiated with 5 MeV deuterons have been determined by the regular deuteron-induced \\/gamma-ray emission (d-PIGE) method and with the selection of the (d,n) reaction channel by measuring \\/gamma-n coincidences. This approach has resulted in a significant improvement of the sensitivity of the analysis. A comparative study with the published

A. Ene; T. Badica; A. Olariu; I. V. Popescu; C. Besliu

2001-01-01

440

The distinction between gamma-quanta spectra from both local sources and cosmic rays, and the formation of a uniform cosmic ray spectrum  

NASA Astrophysics Data System (ADS)

The experimental data about gamma-quanta sources with energy > 1 TeV are characterised by the fact that the observed metagalactic sources (active galactic nuclei) are 106 - 107 times more powerful than the galactic ones, but they do not differ in energy spectrum (F(> E?)~E?-1.3+/-0.15). The power of metagalactic sources and their unlimited number puts into doubt the assumption about the galactic origin of the observable cosmic ray flux. It is possible to assume, that the uniform cosmic ray spectrum is formed (by ``braking'') in an ``infinite'' number of elastic (or inelastic) collisions with relict photons in intergalactic space. Thus, the observable spectral distribution of protons and cosmic ray nuclei with index of (2.72+/-0.02) = 2.718... (the Nipper's number) is the consequence of such ``braking'' warming up the relict photons. RFBR, FNP, GNTP

Nikolsky, S. I.; Sinitsyna, V. G.

2003-07-01

441

Matrix effects in the activity measurement of environmental samples—implementation of specific corrections in a gamma-ray spectrometry analysis program  

Microsoft Academic Search

Based on Monte Carlo simulations, a fast and accurate algorithm for the evaluation of the self-attenuation effects in ?-rays spectrometry has been developed. Using standard compositions for typical environmental samples (but allowing for density variations), an efficient procedure to compute on-line the self-attenuation corrections has been implemented in a dedicated ?-ray analysis program (Environmental Radioactivity Laboratory, Bucharest).

O. Sima; C. Dovlete

1997-01-01

442

Fast time correlation detection in associated particle spectrometry of spontaneous fission neutrons and cosmic-ray backgrounds  

NASA Astrophysics Data System (ADS)

We have investigated neutron spectrometry using fast gamma-ray detectors (BaF2) in coincidence with a gamma/neutron detector (plastic scintillator). Neutron spectra of spontaneous fission sources are determined by time-of-flight between correlated gamma and neutron detections using the associated particle (AP) technique. When the source is within a ~1 meter zone of detector separation, the correlated neutron detection efficiency is high because of the multiplicity of gamma-rays (10 gammas/fission in 252Cf) and neutrons (3.6 neutrons/fission). Cosmic-ray produced neutron detection efficiency is quite low in an AP measurement using a <50ns coincidence window because time-of-flight of most events is long from its creation within the 120 meters e-folding neutron range of air. We found that the AP signal to background ratio was dominated by uncorrelated coincidences and propose a triple coincidence system (1 neutron and 2 gamma-ray detectors) to improve performance. The gamma/gamma-ray coincidence time distribution is related to the target's production history where fast neutron multiplication may be a dominant physical process. MCNPX calculations suggest that the gamma-ray time history of Depleted Uranium (DU) and Highly Enriched Uranium (HEU) provide separable signatures because fast neutron multiplication is much higher in HEU.

Forman, Leon; Dioszegi, Istvan; Vanier, Peter E.

2010-08-01

443

Shape parameter analysis using cloud spectra and gamma functions in the numerical modeling RAMS during LBA Project at Amazonian region, Brazil  

NASA Astrophysics Data System (ADS)

The microphysical variable shape parameters have been investigated considering a numerical simulation based on RAMS (Regional Atmospheric Modeling System), with focus on southwest Amazon Basin during the transition from dry to wet seasons within the scope of LBA (The Large Scale Biosphere Atmosphere Experiment in Amazonia). All data were obtained during the dry-to-wet campaign from September to October 2003. Three precipitation events were chosen during the campaign, classified as polluted, intermediary and clean events. The dataset, for the description of the observed convective systems, includes airborne observations with a microphysics airplane. The variables were cloud droplet contents and spectra, in several flights; radiosonde launches; a 10 cm Doppler radar; visible and IR satellite maps and rain gauge network. The preliminary results have shown that over polluted areas, shape parameters with higher values, from 5 to 7 are better fitted to cloud spectra observations, than the usual shape parameter 2 used in RAMS microphysics default table. For its turn, shape parameter 2 is related to the cleaner areas, i.e., without biomass burning. On the other hand, the numerical simulations, reproducing as close as possible the microphysical variable spatial distributions in the observed dataset, have shown that the average total rainfall precipitation at the surface generally decreases as the CCN concentration and shape parameter increases. CCN vertical and temporal profiles support that result, emphasizing that the higher CCN concentrations are related to biomass burning, where higher shape parameters are better fitted. Additionally, it is possible to conclude that different shape parameters and CCN concentrations may influence directly the maximum and average amount of precipitation and cloud water, implying that different regions should have each the proper specification characteristics. Shape parameters and CCN concentrations are quite useful tools in order to evaluate the spatial and temporal cloud patterns as well as, the rainfall amount with regional implications.

Gonçalves, F. L. T.; Martins, J. A.; Silva Dias, M. A.

2008-07-01

444

A gamma–gamma coincidence spectrometric method for rapid characterization of uranium isotopic fingerprints  

Microsoft Academic Search

This paper reports on initial efforts for uranium isotopic analysis using gamma-rays and X-ray fluorescence coincidence. In\\u000a this study, a gamma–gamma coincidence spectrometry was developed. The spectrometry consists of two NaI(Tl) scintillators and\\u000a XIA LLC Digital Gamma Finder (DGF)\\/Pixie-4 software and card package. The developed spectrometry was optimized according to\\u000a the considerations of output count rate and gamma peak energy

Weihua ZhangJing; Jing Yi; Pawel Mekarski; Kurt Ungar; Barry Hauck; Gary H. Kramer

2011-01-01

445

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

446

Can We Probe the Lorentz Factor of Gamma-ray Bursts from GeV-TeV Spectra Integrated Over Internal Shocks?  

NASA Astrophysics Data System (ADS)

We revisit the high-energy spectral cutoff originating from the electron-positron pair creation in the prompt phase of gamma-ray bursts (GRBs) with numerical and analytical calculations. We show that the conventional exponential and/or broken power-law cutoff should be drastically modified to a shallower broken power law in practical observations that integrate emissions from different internal shocks. Since the steepening is tiny for observations, this "smearing" effect can generally reduce the previous estimates of the Lorentz factor of the GRB outflows. We apply our formulation to GRB 080916C, recently detected by the Large Area Telescope detector on the Fermi satellite, and find that the minimum Lorentz factor can be ~600 (or even smaller values), which is below but consistent with the previous result of ~900. Observing the steepening energy (the so-called "pair-break energy") is crucial to diagnosing the Lorentz factor and/or the emission site in future observations, especially current and future Cherenkov telescopes such as MAGIC, VERITAS, and CTA.

Aoi, Junichi; Murase, Kohta; Takahashi, Keitaro; Ioka, Kunihito; Nagataki, Shigehiro

2010-10-01

447

CAN WE PROBE THE LORENTZ FACTOR OF GAMMA-RAY BURSTS FROM GeV-TeV SPECTRA INTEGRATED OVER INTERNAL SHOCKS?  

SciTech Connect

We revisit the high-energy spectral cutoff originating from the electron-positron pair creation in the prompt phase of gamma-ray bursts (GRBs) with numerical and analytical calculations. We show that the conventional exponential and/or broken power-law cutoff should be drastically modified to a shallower broken power law in practical observations that integrate emissions from different internal shocks. Since the steepening is tiny for observations, this 'smearing' effect can generally reduce the previous estimates of the Lorentz factor of the GRB outflows. We apply our formulation to GRB 080916C, recently detected by the Large Area Telescope detector on the Fermi satellite, and find that the minimum Lorentz factor can be {approx}600 (or even smaller values), which is below but consistent with the previous result of {approx}900. Observing the steepening energy (the so-called 'pair-break energy') is crucial to diagnosing the Lorentz factor and/or the emission site in future observations, especially current and future Cherenkov telescopes such as MAGIC, VERITAS, and CTA.

Aoi, Junichi; Nagataki, Shigehiro [YITP, Kyoto University, Kyoto 606-8502 (Japan); Murase, Kohta [Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Takahashi, Keitaro [Department of Physics and Astrophysics, Nagoya University, Nagoya 464-8602 (Japan); Ioka, Kunihito, E-mail: murase.2@mps.ohio-state.ed [KEK - High Energy Accelerator Research Organization, Tsukuba 305-0801 (Japan)

2010-10-10

448

Determination of fluorine by proton-induced gamma-ray emission (PIGE) spectrometry in igneous and metamorphic charnockitic rocks from Rogaland (S. W. Norway)  

Microsoft Academic Search

More than 200 specimens from different occurrences of the Rogaland igneous complex and surrounding granulite facies metamorphic rocks (S. W. Norway) have been analysed by a direct non-destructive proton induced gamma-ray emission (PIGE) technique. The fluorine contents vary from

I. Roelandts; G. Robaye; G. Weber; J. M. Delbrouck; J. C. Duchesne

1987-01-01

449

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

Microsoft Academic Search

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

M. T. Nikkinen

2005-01-01

450

Gamma-gamma colliders  

SciTech Connect

Gamma-gamma colliders make intense beams of gamma rays and have them collide so as to make elementary particles. The authors show, in this article, that constructing a gamma-gamma collider as an add-on to an electron-positron linear collider is possible with present technology and that it does not require much additional cost. Furthermore, they show that the resulting capability is very interesting from a particle physics point of view. An overview of a linear collider, with a second interaction region devoted to {gamma}{gamma} collisions is shown.

Kim, K.J.; Sessler, A.

1996-06-01

451

Alignment effects in correlation spectra  

SciTech Connect

The structure of nuclei at very high spins can be studied by measuring correlations between ..gamma..-ray energies in the unresolved spectrum emitted. Collective rotations have been shown to produce characteristic features in such correlation spectra. The features produced by the noncollective alignment effects in some high spin Er nuclei are shown here.

Ellegaard, C.; Deleplanque, M.A.; Andersen, O.; Herskind, B.; Stephens, F.S.; Diamond, R.M.; Kluge, H.; Schuck, C.; Shih, S.; Draper, J.E.

1982-03-08

452

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

453

Analysis of MALDI FT-ICR Mass Spectrometry Data: a Time Series Approach  

PubMed Central

Matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry is a technique for high mass-resolution analysis of substances that is rapidly gaining popularity as an analytic tool. Extracting signal from the background noise, however, poses significant challenges. In this article, we model the noise part of a spectrum as an autoregressive, moving average (ARMA) time series with innovations given by a generalized gamma distribution with varying scale parameter but constant shape parameter and exponent. This enables us to classify peaks found in actual spectra as either noise or signal using a reasonable criterion that outperforms a standard threshold criterion.

Kronewitter, Scott R.; Lebrilla, Carlito B.; Rocke, David M.

2009-01-01

454

Analysis of MALDI FT-ICR mass spectrometry data: a time series approach.  

PubMed

Matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry is a technique for high mass-resolution analysis of substances that is rapidly gaining popularity as an analytic tool. Extracting signal from the background noise, however, poses significant challenges. In this article, we model the noise part of a spectrum as an autoregressive, moving average (ARMA) time series with innovations given by a generalized gamma distribution with varying scale parameter but constant shape parameter and exponent. This enables us to classify peaks found in actual spectra as either noise or signal using a reasonable criterion that outperforms a standard threshold criterion. PMID:19646586

Barkauskas, Donald A; Kronewitter, Scott R; Lebrilla, Carlito B; Rocke, David M

2009-07-05

455

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

456

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

NASA Astrophysics Data System (ADS)

We collected spectral gamma data (K, U, Th) and measured sections in cap carbonates (Noonday dolomite) and cap-like carbonates (Beck Spring dolomite) of the Death Valley region in order to explore elemental changes in the post-snowball oceans. The Snowball Earth theory of Hoffman et al. (1998) proposes dramatic post-glacial chemical weathering as large concentrations of carbon were removed from the atmosphere. This would result in a large input of terrigenous material; hence, we expect that carbonates formed under these conditions would demonstrate elevated K, U, Th levels in comparison to carbonates formed under more typical conditions. However, based on our preliminary findings, cap carbonates of the Noonday dolomite and cap-like carbonates of the Beck Spring dolomite have values (0-1% for K, 0.2-6.0 ppm for U, and 0.6-6.9 ppm for Th) that fall within the published range for those measured in carbonates (presumably non-cap or cap-like carbonates). Possible explanations for this include: (a) dilution of any terrigeneous signal by the vast amount of carbonate precipitating in the oceans, or (b) any biological activity that might have an influence on chemical processes in the ocean. A preliminary comparison of our spectral gamma data measured in the Noonday dolomite with published ? 13C data from the same section indicate similar trends in both proxies, namely, a very gradual decrease in values through the majority of the section (Lower Noonday) followed by a more noticeable increase in values in the upper part of the section (Upper Noonday). Further work will be necessary to determine the significance of this possible correlation. Additionally, planned analysis of hand specimens using a high-resolution gamma spectrometer should provide more details about the composition of cap-carbonates and provide further information about the conditions under which they were formed.

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

2004-05-01

457

Atomic Spectra  

NSDL National Science Digital Library

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

Nave, Carl R.

2010-03-12

458

Atomic Spectra  

NSDL National Science Digital Library

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

459

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

PubMed

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

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

2003-11-01

460

In-situ high-resolution gamma-spectrometric survey of burial ground-monitoring wells  

SciTech Connect

In situ high resolution gamma-ray spectrometry with an intrinsic germanium detector assembly of special design surveyed the burial ground monitoring wells to locate and identify gamma emitters that may have migrated from the burial trenches toward the water table. Gamma-ray spectra were acquired as a function of depth in each well and recorded on magnetic tape. These spectra were reduced by a series of computer programs to produce count rate versus depth profiles for natural and man-made activities. The original spectra and the profiles have been archived on magnetic tape for comparison with similar future surveys. Large amounts of man-made activities were observed in some of the burial trenches; however, below the trench bottoms, only very low but detectable amounts of /sup 60/Co and /sup 137/Cs were observed in eleven wells. The highest level of man-made gamma activity observed below the trench bottoms has a count rate roughly equal to that observed for uranium daughter activities which are natural to the subsoil.

Bowman, W.W.

1981-09-01

461

Determination of disulfide bond assignment of human vitamin K-dependent gamma-glutamyl carboxylase by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.  

PubMed

Vitamin K-dependent gamma-glutamyl carboxylase is a 758 amino acid integral membrane glycoprotein that catalyzes the post-translational conversion of certain protein glutamate residues to gamma-carboxyglutamate. Carboxylase has ten cysteine residues, but their form (sulfhydryl or disulfide) is largely unknown. Pudota et al. in Pudota, B. N., Miyagi, M., Hallgren, K. W., West, K. A., Crabb, J. W., Misono, K. S., and Berkner, K. L. (2000) Proc. Natl. Acad. Sci. U. S. A. 97, 13033-13038 reported that Cys-99 and Cys-450 are the carboxylase active site residues. We determined the form of all cysteines in carboxylase using in-gel protease digestion and matrix-assisted laser desorption/ionization mass spectrometry. The spectrum of non-reduced, trypsin-digested carboxylase revealed a peak at m/z 1991.9. Only this peak disappeared in the spectrum of the reduced sample. This peak's m/z is consistent with the mass of peptide 92-100 (Cys-99) disulfide-linked with peptide 446-453 (Cys-450). To confirm its identity, the m/z 1991.9 peak was isolated by a timed ion selector as the precursor ion for further MS analysis. The fragmentation pattern exhibited two groups of triplet ions characteristic of the symmetric and asymmetric cleavage of disulfide-linked tryptic peptides containing Cys-99 and Cys-450. Mutation of either Cys-99 or Cys-450 caused loss of enzymatic activity. We created a carboxylase variant with both C598A and C700A, leaving Cys-450 as the only remaining cysteine residue in the 60-kDa fragment created by limited trypsin digestion. Analysis of this fully active mutant enzyme showed a 30- and the 60-kDa fragment were joined under non-reducing conditions, thus confirming Cys-450 participates in a disulfide bond. Our results indicate that Cys-99 and Cys-450 form the only disulfide bond in carboxylase. PMID:12963724

Tie, Jian-Ke; Mutucumarana, Vasantha P; Straight, David L; Carrick, Kevin L; Pope, R Marshall; Stafford, Darrel W

2003-09-08

462

A nested mixture model for protein identification using mass spectrometry  

Microsoft Academic Search

Mass spectrometry provides a high-throughput way to identify proteins in biological samples. In a typical experiment, proteins in a sample are first broken into their constituent peptides. The resulting mixture of peptides is then subjected to mass spectrometry, which generates thousands of spectra, each characteristic of its generating peptide. Here we consider the problem of inferring, from these spectra, which

Qunhua Li; Michael J. MacCoss; Matthew Stephens

2010-01-01

463

Clustering Millions of Tandem Mass Spectra  

PubMed Central

Summary Tandem mass spectrometry (MS/MS) experiments often generate redundant datasets containing multiple spectra of the same peptides. Clustering of MS/MS spectra takes advantage of this redundancy by identifying multiple spectra of the same peptide and replacing them with a single representative spectrum. Analyzing only representative spectra results in significant speed-up of MS/MS database searches. We present an efficient clustering approach for analyzing large MS/MS datasets (over ten million spectra) with a capability to reduce the number of spectra submitted to further analysis by an order of magnitude. The MS/MS database search of clustered spectra results in fewer spurious hits to the database and increases number of peptide identifications as compared to regular non-clustered searches. Our open source software MS-Clustering is available for download at http://peptide.ucsd.edu or can be run online at http://proteomics.bioprojects.org/MassSpec.

Frank, Ari M.; Bandeira, Nuno; Shen, Zhouxin; Tanner, Stephen; Briggs, Steven P.; Smith, Richard D.; Pevzner, Pavel A.

2008-01-01

464

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

465

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

2012-08-05

466

Exposure of the lysine in the gamma chain dodecapeptide of human fibrinogen is not enhanced by adsorption to poly(ethylene terephthalate) as measured by biotinylation and mass spectrometry  

PubMed Central

Conformational changes in adsorbed fibrinogen may enhance the exposure of platelet adhesive sites that are inaccessible in solution. To test this hypothesis, mass spectrometric methods were developed to quantify chemical modification of lysine residues following adsorption of fibrinogen to biomaterials. The quantitative method used an internal standard consisting of isotope-labeled fibrinogen secreted by human HepG2 cells in culture. Lysine residues in the internal standard were partially reacted with NHS-biotin. For the experimental samples, normal human fibrinogen was adsorbed to polyethylene terephthalate (PET) particles. The adsorbed fibrinogen was reacted with NHS-biotin and then eluted from the particles. Constant amounts of internal standard were added to sample fibrinogen and analyzed by liquid chromatography/tandem mass spectrometry. Biotinylation of the lysine residue in the platelet-adhesive gamma chain dodecapeptide (GCDP) was quantified by comparison to the internal standard. Approximately 80% of the GCDP peptides were biotinylated when fibrinogen was reacted with NHS-biotin in solution, or adsorbed onto PET. These results are generally consistent with previous antibody binding studies and suggest that other regions of fibrinogen may be crucial in promoting platelet adhesion to materials. The results do not directly address but are consistent with the hypothesis that only activated platelets adhere to adsorbed fibrinogen.

Ovod, Vitaliy; Scott, Evan A.; Flake, Megan M.; Parker, Stanley R.; Bateman, Randall J.; Elbert, Donald L.