315 Matching Results

Search Results

Advanced search parameters have been applied.

Indoor Radon and Its Decay Products: Concentrations, Causes, and Control Strategies

Description: This report is an introduction to the behavior of radon 222 and its decay products in indoor air. This includes review of basic characteristics of radon and its decay products and of features of the indoor environment itself, all of which factors affect behavior in indoor air. The experimental and theoretical evidence on behavior of radon and its decay products is examined, providing a basis for understanding the influence of geological, structural, and meteorological factors on indoor concentrations, as well as the effectiveness of control techniques. We go on to examine three important issues concerning indoor radon. We thus include (1) an appraisal of the concentration distribution in homes, (2) an examination of the utility and limitations of popular monitoring techniques and protocols, and (3) an assessment of the key elements of strategies for controlling radon levels in homes.
Date: January 1, 1990
Creator: Nero, A.V.; Gadgil, A.J.; Nazaroff, W.W. & Revzan, K.L.
Partner: UNT Libraries Government Documents Department

The Potential for Dating Groundwater Using Radiogenic Noble Gases

Description: The accumulation in groundwater of products from the radioactive decay of elements naturally found in rocks offers a potential for measuring the time that the groundwater has been contact with the rock. This dating method has an advantage over using decay products from the atmosphere in that the amount of decay products increases with age rather than decreases. However, different decay products accumulate at different rates and, thus, have a different potential usefulness in age determinations. The most useful decay product is helium, produced from uranium and thorium. The use of Ar-40 produced from potassium is limited because Ar-40 is abundant in meteoric water. Neon, xenon and krypton are useful with great difficulty because they are produced in extremely small quantities. In general, the potential for error increases when a long time is required to produce a small quantity of the dating nuclide.
Date: March 23, 2001
Creator: Cornman, W.R.
Partner: UNT Libraries Government Documents Department

The Potential Use of Radioactive Decay Products for Dating Groundwater

Description: The accumulation in groundwater of products from the radioactive decay of elements naturally found in rocks offers a potential for measuring the time that the groundwater has been contact with the rock. This method of dating groundwater has an advantage over using decay products from the atmosphere in that the amount of decay product becomes greater with increasing age rather than less. However, different decay products accumulate at different rates and, thus, have a different potential usefulness in age determinations. The most useful decay product is helium, produced from uranium and thorium. Argon produced from potassium is marginally useful for very old water. Neon, xenon and krypton are probably not useful because they are produced in extremely small quantities. In general, the potential for error increases when a long time to produce a small quantity is required.
Date: March 20, 1980
Creator: Cornman, W.R.
Partner: UNT Libraries Government Documents Department

A dedicated LHC collider Beauty experiment for precision measurements of CP-violation. LHC-B letter of intent

Description: The LHC-B Collaboration proposes to build a forward collider detector dedicated to the study of CP violation and other rare phenomena in the decays of Beauty particles. The forward geometry results in an average 80 GeV momentum of reconstructed B-mesons and, with multiple, efficient and redundant triggers, yields large event samples. B-hadron decay products are efficiently identified by Ring-Imaging Cerenkov Counters, rendering a wide range of multi-particle final states accessible and providing precise measurements of all angles, {alpha}, {beta} and {gamma} of the unitarity triangle. The LHC-B microvertex detector capabilities facilitate multi-vertex event reconstruction and proper-time measurements with an expected few-percent uncertainty, permitting measurements of B{sub s}-mixing well beyond the largest conceivable values of x{sub S}. LHC-B would be fully operational at the startup of LHC and requires only a modest luminosity to reveal its full performance potential.
Date: March 28, 1996
Creator: Crosetto, Dario B.
Partner: UNT Libraries Government Documents Department

Evaluation of selected modern filter media for use in radon/thoron progeny measurements

Description: We tested a number of air sampling filters to determine their suitability for use in radon/thoron progeny measurements. The main test consisted of sampling a radon progeny atmosphere, then measuring the energy spectrum of the alpha particles emerging from the face of the filter. It was found that Millipore AA, long a favorite for this application, is still a good choice. However, this filter is prone to developing electrostatic charge, which can cause the additional collection of {sup 218}Po during filter handling. Metricel DM-800 is also a good choice, and it is less prone to charging. 12 refs., 3 figs., 2 tabs.
Date: April 1, 1996
Creator: Knutson, E.O. & Seo, Kyung-Won
Partner: UNT Libraries Government Documents Department

A conservative evaluation of the transport of TCE from the confined aquifer beneath J-Field, Aberdeen Proving Ground, Maryland, to a hypothetical receptor.

Description: Past disposal operations at the Toxic Burn Pits (TBP) area of J-Field, Aberdeen Proving Ground, Maryland, have resulted in volatile organic compound (VOC) contamination of groundwater. Although the contaminant concentration is highest in the surficial aquifer, VOCs are also present in the confined aquifer, which is approximately 30 m (100 ft) deep at the TBP area. This study focuses on the confined aquifer, a sandy valley-fill Pleistocene unit in a paleochannel cut into Cretaceous sands and clays. This report documents the locations of the region's pumping wells, which are over 6 km (4 mi) away from the TBP. The distances to the pumping wells and the complex stratigraphy limit the likelihood of any contamination reaching a receptor well. Nonetheless, a worst-case scenario was evaluated with a model designed to simulate the transport of trichloroethylene (TCE), the main chemical of concern, from the confined aquifer beneath the TBP along a hypothetical, direct flowpath to a receptor well. The model was designed to be highly conservative (i.e., based on assumptions that promote the transport of contaminants). In addition to the direct flowpath assumption, the model uses the lowest literature value for the biodegradation rate of TCE, a low degree of sorption, a continuous-strength source, and a high flow velocity. Results from this conservative evaluation indicate that the simulated contaminant plume extends into areas offshore from J-Field, but decays before reaching a receptor well. The 5-ppb contour, for example, travels approximately 5 km (3 mi) before stagnating. Recent field analyses have documented that complete biodegradation of TCE to ethene and ethane is occurring directly below the TBP; therefore, the likelihood of TCE or its daughter products reaching a pumping well appears negligible. Thus, the model results may be useful in proposing either a no action or a natural attenuation alternative for the confined ...
Date: January 4, 1999
Creator: Martino, L. E.; Patton, T. L. & Quinn, J. J.
Partner: UNT Libraries Government Documents Department


Description: The occurrence of a fault April 7 caused a short in the stator winding of one of the main generators. Repairs will require at least one month and the total time the generator will be down can be determined only after a further inspection of the damage. In a week or two, after a thorough inspection of the generator and the ignitron system, Bevatron operation will be continued on one generator. Since the targets of use in a Bevatron experiment will depend greatly on the nature of the experiment and the techniques to be employed the ideas presented here relate primarily to the area of research which involves the detection with counters of heavy mesons emitted in the backward direction in the laboratory system. These mesons and their decay products have low kinetic energy over the entire range of Bevatron energies above threshold for production. For this reason discrimination by means of momentum resolution, collimating slits, ionization density and range will be possible.
Date: April 13, 1954
Creator: Lofgren, E.J.
Partner: UNT Libraries Government Documents Department

Muon collider interaction region design

Description: Design of a muon collider interaction region (IR) presents a number of challenges arising from low {beta}* < 1 cm, correspondingly large beta-function values and beam sizes at IR magnets, as well as the necessity to protect superconducting magnets and collider detectors from muon decay products. As a consequence, the designs of the IR optics, magnets and machine-detector interface are strongly interlaced and iterative. A consistent solution for the 1.5 TeV c.o.m. muon collider IR is presented. It can provide an average luminosity of 10{sup 34} cm{sup -2}s{sup -1} with an adequate protection of magnet and detector components.
Date: May 1, 2010
Creator: Alexahin, Y.I.; Gianfelice-Wendt, E.; Kashikhin, V.V.; Mokhov, N.V.; Zlobin, A.V.; /Fermilab et al.
Partner: UNT Libraries Government Documents Department

Experimental Determination of Li, Be and B Partitioning During CAI Crystallization

Description: The main focus of the work is to develop a better understanding of the distribution of the elements B, Be and Li in melilite, fassaitic clinop clinopy-roxene, anorthite and spinel, which are the primary constituents of calcium-aluminum-rich inclusions (CAIs). These elements are the parent or decay products of short-lived nuclides (specifically, {sup 7}Be and {sup 10}Be) formed by cosmic ray spallation reactions on silicon and oxygen. Recent observations suggest that some CAIs contain ''fossil'' {sup 7}Be and {sup 10}Be in the form of ''excess'' amounts of their decay products (B and Li). The exact timing of {sup 7}Be and {sup 10}Be production is unknown, but if it occurred early in CAI history, it could constrain the birthplace of CAIs to be within a limited region near the infant sun. Other interpretations are possible, however, and bear little significance to early CAI genesis. In order to interpret the anomalies as being ''primary'', and thus originating at high temperature, information on the intermineral partitioning of both parent and daughter elements is required.
Date: January 12, 2005
Creator: Ryerson, F J; Brenan, J M & Phinney, D L
Partner: UNT Libraries Government Documents Department


Description: J-Integral fracture toughness tests were conducted on tritium-exposed-and-aged Types 304L and 21-6-9 stainless steel weldments in order to measure the combined effects of tritium and its decay product, helium-3 on the fracture toughness properties. Initially, weldments have fracture toughness values about three times higher than base-metal values. Delta-ferrite phase in the weld microstructure improved toughness provided no tritium was present in the microstructure. After a tritium-exposure-and-aging treatment that resulted in {approx}1400 atomic parts per million (appm) dissolved tritium, both weldments and base metals had their fracture toughness values reduced to about the same level. The tritium effect was greater in weldments (67 % reduction vs. 37% reduction) largely because the ductile discontinuous delta-ferrite interfaces were embrittled by tritium and decay helium. Fracture toughness values decreased for both base metals and weldments with increasing decay helium content in the range tested (50-200 appm).
Date: August 31, 2007
Creator: Morgan, M; Scott West, S & Michael Tosten, M
Partner: UNT Libraries Government Documents Department


Description: The fracture toughness data collected in this study are needed to assess the long-term effects of tritium and its decay product on tritium reservoirs. The results show that tritium and decay helium have negative effects on the fracture toughness properties of stainless steel and its weldments. The data and report from this study has been included in a material property database for use in tritium reservoir modeling efforts like the Technology Investment Program ''Lifecycle Engineering for Tritium Reservoirs''. A number of conclusions can be drawn from the data: (1) For unexposed Type 304L stainless steel, the fracture toughness of weldments was two to three times higher than the base metal toughness. (2) Tritium exposure lowered the fracture toughness properties of both base metals and weldments. This was characterized by lower J{sub Q} values and lower J-da curves. (3) Tritium-exposed-and-aged base metals and weldments had lower fracture toughness values than unexposed ones but still retained good toughness properties.
Date: September 26, 2006
Creator: Morgan, M; Scott West, S & Michael Tosten, M
Partner: UNT Libraries Government Documents Department


Description: {sup 3}He recovery is a topic of recent interest. One potential recovery source is from metal hydride materials once used to store tritium, as the decay product, {sup 3}He, is primarily trapped in the metal lattice, usually in bubbles, with such materials. In 2001, a Tritium Exposure Program (TEP) sample known as LANA75-SP1 was retired and the material was removed from the test cell and stored. Subsequently scoping temperature programmed desorption (TPD) experiments were conducted on that material to see what it might take to drive out He and residual H isotopes (the heel). Two experiments consisted of heating the sample in the presence of an excess of tin (the so-called Sn fusion experiment), and one was a simple TPD with no additives. Prior data on the so-called '21-month bed' material in the 1980's had produced {approx}21 cc of gas per gram of a LANA30 material (LaNi4.7Al0.3), with approximately 67% of that being {sup 3}He and the rest being D{sub 2} (Fig.3). However, the material had to be heated in excess of 850 C to obtain that level. Heating to less produced approximately half that amount of gas. The data also showed that {sup 3}He was released at different temperatures than the residual hydrogen isotopes. Unfortunately this implies full {sup 3}He recovery will be a difficult process. Therefore, it seemed advisable to attempt to extract as much information from the 3 scoping experiments from 2001-2 as possible.
Date: December 1, 2010
Creator: Shanahan, K.
Partner: UNT Libraries Government Documents Department


Description: The burst test is used to assess the material performance of tritium reservoirs in the surveillance program in which reservoirs have been in service for extended periods of time. A materials system model and finite element procedure were developed under a Savannah River Site Plant-Directed Research and Development (PDRD) program to predict the structural response under a full range of loading and aged material conditions of the reservoir. The results show that the predicted burst pressure and volume ductility are in good agreement with the actual burst test results for the unexposed units. The material tensile properties used in the calculations were obtained from a curved tensile specimen harvested from a companion reservoir by Electric Discharge Machining (EDM). In the absence of exposed and aged material tensile data, literature data were used for demonstrating the methodology in terms of the helium-3 concentration in the metal and the depth of penetration in the reservoir sidewall. It can be shown that the volume ductility decreases significantly with the presence of tritium and its decay product, helium-3, in the metal, as was observed in the laboratory-controlled burst tests. The model and analytical procedure provides a predictive tool for reservoir structural integrity under aging conditions. It is recommended that benchmark tests and analysis for aged materials be performed. The methodology can be augmented to predict performance for reservoir with flaws.
Date: November 10, 2005
Creator: Lam, P.S. & Morgan, M.J
Partner: UNT Libraries Government Documents Department

A high-power target experiment at the CERN PS

Description: We test a target concept devised for the purpose of producing copious secondary pions and capturing the muon decay products. This experiment is designed to test the target system for a neutrino factory or muon collider and consists of a free flowing mercury stream embedded in a high-field solenoid. Key components are described.
Date: June 1, 2007
Creator: Kirk, H.G.; Park, H.J.; Tsang, T.; /Brookhaven; Fabich, A.; Efthymiopoulos, I. et al.
Partner: UNT Libraries Government Documents Department

Density changes in Ga-stabilized delta-Pu, and what they mean

Description: Ga-stabilized {delta}-Pu undergoes small changes in density with time. These have been associated with four different causes: an initial reversible expansion that saturates after a short time; a continuous change that can be attributed to the in-growth of helium and actinide daughter products from the radioactive decay of plutonium; possible void swelling; and phase instability. We review our present understanding of these processes and evaluate their contributions to density changes. It is shown that the initial transient expansion is intimately connected with the metastability of the {delta}-phase at ambient temperature.
Date: September 8, 2006
Creator: G.Wolfer, W; Kubota, A; S?derlind, P; Landa, A; Oudot, B; Sadigh, B et al.
Partner: UNT Libraries Government Documents Department

New Neutron Rich Nuclei Near {sup 208}Pb

Description: The level properties near the stable doubly-magic nuclei formed the experimental grounds for the theoretical description of nuclear structure. However with a departure from the beta-stability line, the classical well-established shell structure might be modified. In particular, it may even vanish for extremely exotic neutron-rich nuclei near the neutron-drip line. Presently, it is impossible to verify such predictions by a direct experimental studies of these exotic objects. However, one may try to observe and understand the evolution of the nuclear structure while departing in the experiment as far as possible from the stable nuclei. An extension of experimental nuclear structure studies towards the nuclei characterized by high neutron excess is crucial for such verifications as well as for the {tau}-process nucleosynthesis scenario. Heavy neutron-rich nuclei, south-east of doubly-magic {sup 208}Pb, were always very difficult to produce and investigate. The nuclei like {sup 218}Po and {sup 214}Pb or {sup 210}Tl marked the border line of known nuclei from the beginning of the radioactivity era for over ninety years. To illustrate the difficulties, one can refer to the experiments employing the on-line mass separator technique. A spallation of heavy targets like {sup 232}Th and {sup 238}U by high-energy protons was proven as a source of heavy neutron-rich nuclei. The isotopes near and beyond doubly-magic {sup 208}Pb were produced too. However, such studies often suffered from an isobaric contamination of much more strongly produced and efficiently released elements like francium or radon and their decay products. A new experimental technique, based on the pulsed release element selective method recently developed at the PS Booster-ISOLDE at CERN [7,8,9] greatly reduces the contamination of these very short-lived {alpha}-emitters (Z {ge} 84) for the isobaric mass chains A=215 to A=218.
Date: November 13, 1998
Creator: Aeystoe, J.; Andreyev, A.; Evensen, A.-H.; Hoff, P.; Huhta, M.; Huyse, M. et al.
Partner: UNT Libraries Government Documents Department

Short- and long-lived radionuclide particle size measurements in a uranium mine

Description: The radon-222 progeny and long-lived radionuclide measurements were done in a wet underground uranium mine in Saskatchewan, Canada, on Nov. 8-12, 1995. Radon-222 in the mine varied from 2 kBq/m{sup 3} at 90 m below surface to 12 kBq/m{sup 3} in the mining areas, 240 m below surface. Radon-222 progeny activity and potential alpha energy concentration appear affected by the airborne particle number concentration and size distribution. Particle number was up to 200x10{sup 3}/cm{sup 3}. Only an accumulation mode (30-1000 nm) and some bimodal size distributions in this accumulation size range were significant. Diesel particles and combustion particles from burning propane caused a major modal diameter shift to a smaller size range (50-85 nm) compared with previous values (100-200 nm). The high particle number reduced the unattached progeny (0.5-2 nm) to >5%. The nuclei mode (2-30 nm) in this test was nonexistent, and the coarse mode (>1000 nm), except from the drilling areas and on the stopes, was mostly not measurable. Airborne particle total mass and long- lived radionuclide alpha activity concentrations were very low (80- 100 {mu}g/m{sup 3} and 4-5 mBq/m{sup 3}) owing to high ventilation rates. Mass-weighted size distributions were trimodal, with the major mode at the accumulation size region, which accounts for 45-50% of the mass. The coarse model contains the the least mass, about 20%. The size spectra from gross alpha activities were bimodal with major mode in the coarse region (>1000 nm) and a minor accumulation mode in the 50-900 nm size range. These size spectra were different from the {sup 222}Rn progeny that showed a single accumulation mode in the 50- 85 nm size region. The accumulation mode in the long-lived radionuclide size spectrum was not found in previous studies in other uranium mines.
Date: April 1, 1997
Creator: Tu, Keng-Wu; Fisenne, I.M. & Hutter, A.R.
Partner: UNT Libraries Government Documents Department

Intercomparison of active, passive and continuous instruments for radon and radon progeny measurements in the EML chamber and test facility

Description: The results from the May 1995 Intercomparison of Active, Passive and Continuous Instruments for Radon and Radon Progeny Measurement conducted in the EML radon exposure and test facility are presented. Represented were 13 participants that measure radon with open faced and diffusion barrier activated carbon collectors, 10 with nuclear alpha track detectors, 9 with short-term and long-term electret/ionization chambers, and 13 with active and passive commercial electronic continuous monitors. For radon progeny, there were four participants that came in person to take part in the grab sampling methodology for measuring individual radon progeny and the potential alpha energy concentration (PAEC). There were 11 participants with continuous and integrating commercial electronic instruments that are used for measuring the PAEC. The results indicate that all the tested instruments that measure radon fulfill their intended purpose. All instruments and methods used for grab sampling for radon progeny did very well. However, most of the continuous and integrating electronic instruments used for measuring the PAEC or working level appear to underestimate the potential risk from radon progeny when the concentration of particles onto which the radon progeny are attached is <5,000 cm{sup -3}.
Date: December 1, 1995
Creator: George, A.C.; Knutson, E.O.; Tu, K.W. & Fisenne, I.M.
Partner: UNT Libraries Government Documents Department

Personal and Environmental Exposure Assessment Measurements at Fernald

Description: The research is directed to developing state-of-the-art personal and environmental exposure assessment for inhaled radionuclides at Fernald during D&amp;D. An additional objective is the radiochemical analyses of soil samples taken around the radium (K-65) silos before and after removal of the material. Lead-210, the long lived decay product of radon released during the removal, provides a sensitive tracer to determine the entire inventory of radon released.
Date: June 1, 2000
Creator: Harley, Naomi, H.
Partner: UNT Libraries Government Documents Department

Radon progeny inhalation study as applicable to uranium mining. Fourth annual progress report covering the calendar year 1968

Description: This annual report describes recent progress as a collection of abstracts and brief reports largely prepared by graduate students. Included is one full paper on Radiation Standards for Uranium Mining, Radon Progeny Concentration Units. Individual papers are separately indexed and abstracted for the database.
Date: February 28, 1969
Creator: Schiager, K.J. & Dahl, A.H.
Partner: UNT Libraries Government Documents Department

Measurement of the Ratio BR(B+ to X e nu) / BR(B0 to X e nu)

Description: The authors report measurements of the inclusive electron momentum spectra in decays of charged and neutral B mesons, and of the ratio of semileptonic branching fractions {Beta}(B{sup +} {yields} Xe{nu}) and {Beta}(B{sup 0} {yields} Xe{nu}). These were performed on a sample of 231 million B{bar B} events recorded with the BABAR detector at the {Upsilon}(4S) resonance. Events are selected by fully reconstructing a hadronic decay of one B meson and identifying an electron among the decay products of the recoiling {bar B} meson. They obtain {Beta}(B{sup +} {yields} Xe{nu})/{Beta}(B{sup 0} {yields} Xe{nu}) = 1.084 {+-} 0.041{sub (stat)} {+-} 0.025{sub (syst)}.
Date: December 6, 2006
Creator: Aubert, B.; Bona, M.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
Partner: UNT Libraries Government Documents Department