669 Matching Results

Search Results

Advanced search parameters have been applied.

Radioactivity of Potassium Solutions: A Comparison of Calculated Activity to Measured Activity from Gross Beta Counting and Gamma Spectroscopy

Description: In order to determine if the measured beta activity for a solution containing potassium was exactly as predicted, particularly since the CES gas counter is not calibrated specifically with K-40, an experiment was conducted to compare measured activities from two radioanalytical methods (gamma spectroscopy and gas proportional counting) to calculated activities across a range of potassium concentrations. Potassium, being ubiquitous and naturally radioactive, is a well-known and common interference in gross beta counting methods. By measuring the observed beta activity due to K-40 in potassium-containing solutions across a wide range of concentrations, it was found that the observed beta activity agrees well with the beta activity calculated from the potassium concentration measured by standard inorganic analytical techniques, such as ICP-OES, and that using the measured potassium concentration to calculate the expected beta activity, and comparing this to the observed beta activity to determine if potassium can account for all the observed activity in a sample, is a valid technique. It was also observed that gamma spectroscopy is not an effective means of measuring K-40 activity below approximately 700 pCi/L, which corresponds to a solution with approximately 833 mg/L total potassium. Gas proportional counting for gross beta activity has a much lower detection limit, typically 20-50 picoCi/L for a liquid low in total dissolved solids, which corresponds to a potassium concentration of approximately 30-70 ppm K.
Date: July 26, 2005
Creator: Gaylord, R F
Partner: UNT Libraries Government Documents Department

Nuclear shape and structure in neutron-rich 110,111Tc

Description: The structure of Tc nuclei is extended to the moreneutron-rich regions based on measurements of prompt gamma rays from thespontaneous fission of 252Cf at Gammasphere. The level scheme of N=67neutron-rich (Z=43) 110Tc is established for the first time and that of111Tc is expanded. The ground-state band of 111Tc reaches theband-crossing region and the new observation of the weakly populatedalpha = -1/2 member of the band provides important information ofsignature splitting. The systematics of band crossings in the isotopicand isotonic chains and a CSM calculation suggest that the band crossingof the gs band of 111Tc is due to alignment of a pair of h11/2 neutrons.The best fit to signature splitting, branching ratios, and excitations ofthe ground-state band of 111Tc by RTRP model calculations result in ashape of epsilon2 = 0.32 and gamma = -26 deg. for this nucleus. Itstriaxiality is larger than that of 107Tc, to indicate increasingtriaxiality with increasing neutron number. The identification of theweakly-populated "K+2 satellite" band provides strong evidence for thelarge triaxiality of 111Tc. In 110Tc the four lowest-lying levelsobserved are very similar to those in 108Tc. At an excitation of 478.9keV above the lowest state observed, ten states of a delta I = 1 band areobserved. This band is very analogous to the delta I = 1 bands in106,108Tc, but it has greater signature splitting at higherspins.
Date: February 2, 2006
Creator: Luo, Y.X.; Hamilton, J.H.; Rasmussen, J.O.; Ramayya, A.V.; Stefanescu, I.; Hwang, J.K. et al.
Partner: UNT Libraries Government Documents Department

Section on prospects for dark matter detection of the white paper on the status and future of ground-based TeV gamma-ray astronomy.

Description: This is a report on the findings of the dark matter science working group for the white paper on the status and future of TeV gamma-ray astronomy. The white paper was commissioned by the American Physical Society, and the full white paper can be found on astro-ph (arXiv:0810.0444). This detailed section discusses the prospects for dark matter detection with future gamma-ray experiments, and the complementarity of gamma-ray measurements with other indirect, direct or accelerator-based searches. We conclude that any comprehensive search for dark matter should include gamma-ray observations, both to identify the dark matter particle (through the characteristics of the gamma-ray spectrum) and to measure the distribution of dark matter in galactic halos.
Date: May 13, 2009
Creator: Byrum, K.; Horan, D.; Tait, T.; Wanger, R.; Zaharijas, G.; Buckley , J. et al.
Partner: UNT Libraries Government Documents Department

Reference Material for Radionuclides in Sediment, IAEA-384 (Fangataufa Lagoon Sediment)

Description: The IAEA Marine Environment Laboratory (IAEA-MEL) in Monaco has conducted intercomparison exercises on radionuclides in marine samples for many years as part of its contribution to the IAEA's program of Analytical Quality Control Services (AQCS). An important part of the AQCS program has been a production of Reference Materials (RMs) and their provision to radioanalytical laboratories. The RMs have been developed for different marine matrices (sediment, water, biota), with accuracy and precision required for the present state of the art of radiometrics and mass spectrometry methods. The RMs have been produced as the final products of world-wide intercomparison exercises organized during last 30 years. A total of 44 intercomparison exercises were undertaken and 39 RMs were produced for radionuclides in the marine environment. All required matrices (seawater, biota, sediment) have been covered with radionuclide concentrations ranging from typical environmental levels to elevated levels affected by discharges from nuclear reprocessing plants. The long-term availability of RMs (over 10 years) requires the use of very specific techniques to collect and pretreat large quantities of material (e.g., in excess of 100 kg) in order to ensure sample stability and homogenization of any analytes of interest. The production of a RM is therefore a long process, covering the identification of needs, sample collection, pre-treatment, homogenization, bottling, distribution to laboratories, evaluation of data, preliminary reporting, additional analyses in expert laboratories, certification of the material, and finally issuing the RM. In this paper we describe a reference material IAEA-384, Fangataufa lagoon sediment, designed for determination of anthropogenic and natural radionuclides in the marine environment. This RM has been prepared with the aim of testing the performance of analytical laboratories to measure the activity of these radionuclides in a sediment sample contaminated by elevated levels of fallout from nuclear weapons tests. Participating laboratories were requested to determine ...
Date: September 23, 2005
Creator: Povinec, P; Pham, M; Barci-Funel, G; Bojanawski, R; Boshkova, T; Burnett, W et al.
Partner: UNT Libraries Government Documents Department

State-of-the-Art Beta Detection and Dosimetry

Description: The research funded by this NEER grant establishes the framework for a detailed understanding of the challenges in beta dosimetry, especially in the presence of a mixed radiation field. The work also stimulated the thinking of the research group which will lead to new concepts in digital signal processing to allow collection of detection signals and real-time analysis such that simultaneous beta and gamma spectroscopy can take place. The work described herein (with detail in the many publications that came out of this research) was conducted in a manner that provided dissertation and thesis topics for three students, one of whom was completely funded by this grant. The overall benefit of the work came in the form of a dramatic shift in signal processing that is normally conducted in analog pulse shape analysis. Analog signal processing was shown not to be feasible for this type of work; digital signal processing was a must. This, in turn, led the research team to a new understanding of pulse analysis, one in which expands the state-of-the-art in simultaneous beta and gamma spectroscopy with a single detector.
Date: August 15, 2008
Creator: Hamby, David M.
Partner: UNT Libraries Government Documents Department

Report on Second Activations with the Lead Slowing Down Spectrometer

Description: Summary On August 18 and 19 2011, five items were irradiated with neutrons using the Lead Slowing Down Spectrometer (LSDS). After irradiation, dose measurements and gamma-spectrometry measurements were completed on all of the samples. No contamination was found on the samples, and all but one provided no dose. Gamma-spectroscopy measurements qualitatively agreed with expectations based on the materials. As during the first activation run, we observed activation in the room in general, mostly due to 56Mn and 24Na. Most of the activation of the samples was short lived, with half-lives on the scale of hours to days, except for 60Co which has a half-life of 5.3 y.
Date: April 27, 2012
Creator: Stave, Sean C.; Mace, Emily K.; Pratt, Sharon L. & Warren, Glen A.
Partner: UNT Libraries Government Documents Department

High resolution gamma spectroscopy well logging system

Description: A Gamma Spectroscopy Logging System (GSLS) has been developed to study sub-surface radionuclide contamination. The absolute counting efficiencies of the GSLS detectors were determined using cylindrical reference sources. More complex borehole geometries were modeled using commercially available shielding software and correction factors were developed based on relative gamma-ray fluence rates. Examination of varying porosity and moisture content showed that as porosity increases, and as the formation saturation ratio decreases, relative gamma-ray fluence rates increase linearly for all energies. Correction factors for iron and water cylindrical shields were found to agree well with correction factors determined during previous studies allowing for the development of correction factors for type-304 stainless steel and low-carbon steel casings. Regression analyses of correction factor data produced equations for determining correction factors applicable to spectral gamma-ray well logs acquired under non-standard borehole conditions.
Date: May 1, 1997
Creator: Giles, J.R. & Dooley, K.J.
Partner: UNT Libraries Government Documents Department

An Evaluation of Activated Bismuth Isotopes in Environmental Samples From the Former Western Pacific Proving Grounds

Description: {sup 207}Bi (t{sub 1/2}=32.2 y) was generated by activation of weapons material during a few ''clean'' nuclear tests at the U.S. Western Pacific Proving Grounds of Enewetak and Bikini Atolls. The radionuclides first appeared in the Enewetak environment during 1958 and in the environment of Bikini during 1956. Crater sediments from Bikini with high levels of {sup 207}Bi were analyzed by gamma spectrometry in an attempt to determine the relative concentrations of {sup 208}Bi (t{sup 1/2} = 3.68 x 10{sup 5} y). The bismuth isotopes were probably generated during the ''clean'', 9.3 Mt Poplar test held on 7/12/58. The atom ratio of {sup 208}Bi to {sup 207}Bi (R value) ranges from {approx}12 to over 200 in sections of core sediments from the largest nuclear crater at Bikini atoll. The presence of bismuth in the device is suggested to account for R values in excess of 10.
Date: March 21, 2000
Creator: Robison, W.L.; Brunk, J.A. & Jokela, T.A.
Partner: UNT Libraries Government Documents Department

Gamma-ray pulse height spectrum analysis on systems with multiple Ge detectors using a spectrum summing

Description: A technique has been developed at the Idaho National Engineering Laboratory to sum high resolution gamma-ray pulse spectra from systems with multiple Ge detectors. Lockheed Martin Idaho Technologies Company operates a multi-detector spectrometer configuration at the Stored Waste Examination Pilot Plant facility which is used to characterize the radio nuclide contents in waste drums destined for shipment to Waste Isolation Pilot Plant. This summing technique was developed to increase the sensitivity of the system, reduce the count times required to properly quantify the radionuclides and provide a more consistent methodology for combining data collected from multiple detectors. In spectrometer systems with multiple detectors looking at non homogenous waste forms it is often difficult to combine individual spectrum analysis results from each detector to obtain a meaningful result for the total waste container. This is particularly true when the counting statistics in each individual spectrum are poor. The spectrum summing technique adds the spectra collected by each detector into a single spectrum which has better counting statistics than each individual spectrum. A normal spectral analysis program can then be used to analyze the sum spectrum to obtain radio nuclide values which have smaller errors and do not have to be further manipulated to obtain results for the total waste container.
Date: May 1, 1997
Creator: Killian, E.W.
Partner: UNT Libraries Government Documents Department

Measurement of gamma activity from the PUREX stack, Number 296-A-10, HEPA filters

Description: In response to the Environmental Protection Agency`s requirements for evaluating radioactive emissions from stacks, this test plan was developed. The test plan employs the use of low resolution (NaI) portable gamma spectrometry to identify and measure gamma emitting radionuclides from HEPA filters. The test description, expected results, and test set-up and steps are discussed.
Date: November 1, 1995
Creator: Barnett, J. M.
Partner: UNT Libraries Government Documents Department

The Spectroscopy of {sup 183}Tl: An Extreme Case of Prolate-Oblate Shape-Competition

Description: The yrast sequence in {sup 183}Tl has been studied for the first time in recoil-mass and decay tagged gamma-ray spectroscopic measurements. A rotational-like cascade of seven transitions is observed down to the bandhead with spin 13/2+. In contrast to adjacent nuclei, links from the yrast band to a lower lying weakly deformed (oblate) structure are not observed. It appears that the prolate energy minimum in {sup 183}Tl drops significantly compared to {sup 185}Tl and minimizes below the neutron i13/2 midshell (n <= 102). Possibilities for the decay out of the band in {sup 183}Tl are discussed.
Date: August 10, 1998
Creator: Batchelder, J.C.; Bingham, C.R.; Carpenter, M.P.; Cizewski, J.A.; Gross, C.J.; Helariutta, K. et al.
Partner: UNT Libraries Government Documents Department

Gamma ray scanner systems for nondestructive assay of heterogeneous waste barrels

Description: Traditional gamma safeguards measurements have usually been performed using a segmented gamma scanning (SGS) system. The accuracy of this technique relies on the assumption that the sample matrix and the activity are both uniform for a segment. Waste barrels are often highly heterogeneous, span a wide range of composition and matrix type. The primary sources of error are all directly or indirectly related to a non-uniform measurement response associated with unknown radioactive source spatial distribution and heterogeneity of the matrix. These errors can be significantly reduced by some imaging techniques that measure exact spatial locations of sources and attenuation maps. In this paper we describe a joint R&D effort between the Lawrence Livermore National Laboratory (LLNL) and the Institute of Nuclear Techniques (INT) of the Technical University, Budapest, to compare results obtained by two different gamma-ray nondestructive assay (NDA) systems used for imaging waste barrels. The basic principles are the same, but the approaches are different. Key factors to judge the adequacy of a method are the detection limit and the accuracy. Test drums representing waste to be measured are used to determine basic parameters of these techniques.
Date: March 25, 1997
Creator: Martz, H.E.; Decman, B.J.; Roberson, G.P. & Levai, F.
Partner: UNT Libraries Government Documents Department

Mapping the elemental composition of the moon: Current results of the Lunar Prospector gamma ray spectrometer

Description: One of the instruments on board the recently launched Lunar Prospector spacecraft is a Gamma-Ray Spectrometer (GRS) designed to map the surface elemental composition of the Moon. Specifically, the objectives of the GRS are to map abundances of Fe, Ti, U, Th, K, Si, O and if possible Mg, Al, and Ca. The GRS consists of a bismuth germanate (BGO) crystal placed within a well shaped borated plastic scintillator anti-coincidence (ACS) shield. Events triggering only the BGO are labeled as accepted events; events triggering both the BGO and ACS are labeled as rejected events. BGO spectra for both accepted and rejected events are telemetered to the ground for later analysis. Results of the study are given.
Date: December 1, 1998
Creator: Lawrence, D.J.; Feldman, W.C.; Barraclough, B.L.; Elphic, R.C.; Binder, A.B. & Maurice, S.
Partner: UNT Libraries Government Documents Department

Age of the Harrison Street Beast: Electron paramagnetic resonance spectra from tooth enamel

Description: Workers doing road reconstruction in 1993 in Fort Wayne, Indiana, uncovered remains of a large skeleton and contacted archaeologists for assessment prior to continuing work. The archaeologists excavated the remains which were located in a 19-cm thick layer of blue glay, a pedological deposit which forms from wet, anaerobic environments associated with bogs. This glay layer was located some 2 meters below the current ground level (Davenport 1996). In this paper, the authors present the results of an EPR analysis of tooth enamel (biogenic hydroxyapatite) from the Harrison Street Beast. The objectives of this study are: (1) determine an age for the specimen through EPR analysis of molar tooth enamel; (2) resolve and identify the radiation sensitive EPR spectral components; and (3) develop a provisional model for the creation of radiation-sensitive components in the EPR spectra.
Date: April 1, 1998
Creator: Weeks, R.A.; Elam, J.M.; Davenport, C. & Bogard, J.S.
Partner: UNT Libraries Government Documents Department