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3 results on '"Gahl, A."'

1. An Ion Emission Source for Portable Active Interrogation.

Author

Baxter, E., Kovaleski, S., Benwell, A., Kwon, J., Wacharasindhu, T., and Gahl, J.

Subjects
ELECTRONIC systems, DEUTERIUM ions, EMISSIONS (Air pollution), NUCLEAR reactions
Abstract

Detection of nuclear materials in containers is possible by probing the container with energetic particles to induce a measurable nuclear reaction. This form of active interrogation could be used in the shipping industry to quickly locate illicit material at large shipping hubs. In order for active interrogation to become a viable method for detection, active interrogation systems must become highly portable. The University of Missouri is developing an ultra compact deuterium ion accelerator to induce D-D fusion as a source of neutrons for detection purposes. The portable system employs a small high voltage accelerator to which a field desorption ion emitting structure can be fixed. The structure will desorb deuterium ions that are then accelerated into a deuterated target inducing a D + D → 3He + n reaction. The 2.6-MeV neutron that is produced can be used for probing containers to determine if radioactive material is present. Emission structures are being considered in single, patterned and unpatterned arrays made of molybdenum and tungsten with varying field enhancement. Ion emission resulting from the various types of structures is measured and presented along with details of their design and manufacture. [ABSTRACT FROM AUTHOR]

Published
2009

2. Avifauna richness enhanced in large, isolated urban parks.

Author

Oliver, Amanda J., Hong-Wa, Cynthia, Devonshire, Jodi, Olea, Kelly R., Rivas, Gonzalo F., and Gahl, Megan K.

Subjects
BIRD migration, SPECIES diversity, URBAN parks, BIRDS, BIOGEOGRAPHY, URBANIZATION, MISSISSIPPI flyway, BIRD habitats
Abstract

Abstract: Urbanization causes fragmentation creating “islands” of natural habitat. The resulting fragmented landscapes represent a challenge for migratory and resident species because of decreased connectivity among fragments. We examined the effects of urbanization on avifauna communities in remnant and restored parks in the greater St. Louis area (St. Louis), Missouri and Illinois, USA. St. Louis is located along the Mississippi flyway, a significant North American migratory bird route, and ranks second among the most sprawl-threatened large cities. We compiled bird assemblages for 20 parks and used multiple linear regressions and Akaike''s Information Criterion (AIC) to analyze seven potential predictors of species richness for breeding, migratory and wintering species: area, habitat diversity, external development within 1km and 5km buffers, internal developed areas, road length, and presence of water bodies. The best predictors of resident bird (i.e., breeding and wintering) species richness was park area and external developed area within 5km, a surrogate for isolation. We suspect that the high species richness in parks in heavily urbanized areas is explained by the parks’ relatively large size and the funneling of species to two large parks within the most urbanized areas of St. Louis. For migratory species, the best predictors were habitat diversity and developed area within the park. As development continues to transform natural habitat along important avian migratory flyways, urban planning that includes large, diverse natural areas within urbanized landscapes is key to conserving local and migratory avifauna diversity. [Copyright &y& Elsevier]

Published
2011
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3. MOCK FUEL STORAGE MBA AT MURR.

Author

Weaver, Charles L., Cole, James S., Flagg, Michael A., Foyto, Leslie P., Gahl, John M., Trauth, Kathleen M., Robertson, J. David, and Miller, William H.

Subjects
NUCLEAR fuels, STORAGE facilities -- Design & construction
Abstract

In conjunction with the 2009 State Systems of Accounting for and Control of Nuclear Materials Course (SSAC), a mock up of a possible fresh fuel storage area was constructed at the University of Missouri Research Reactors (MURR) as an example of a material balance area (MBA) that applies the principles of material control and accounting in both design and operation. The MBA contains key measurement points (KMPs) that maintain control of enclosed nuclear materials while controlling personnel access to the nuclear materials throughout the material balance period by using access control systems. These access controls will facilitate timely and accurate identification of potential diversion attempts of the nuclear material as well as provide for standard methods of accounting for the fresh nuclear fuel as it moves within the facility. [ABSTRACT FROM AUTHOR]

Published
2009

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