Authors:A. Michenaud-Rague, S. Robinson, and S. Landsberger
While there is a lot of information on the elemental content of food for nutritional and pollution studies, the analysis of
fruits has received little attention. We have investigated 11 commonly eaten fruits for their trace and minor element constituents
by neutron activations including thermal and epithermal neutron activation analysis. Our results revealed that both blueberries
and strawberries had the most of top two highest elemental concentrations followed by raspberries, oranges and mango. Bananas,
grapes, plums, apples, pears, and cherries had the fewest or none of the most elevated elemental concentrations.
Authors:S. Robinson, E. Siciliano, and J. Schweppe
Developing and testing improved alarm algorithms is a priority of the Radiation Portal Monitor Project (RPMP) at PNNL. Improved
algorithms may reduce the potential impediments that radiation screening presents to the flow of commerce, without affecting
the detection sensitivity to sources of interest. However, assessing alarm-algorithm performance involves calculation of both
detection probabilities and false alarm rates. For statistical confidence, this requires a large amount of data from drive-through
(or “dynamic”) scenarios both with, and without, sources of interest, but this is usually not feasible. Instead, an “injection-study”
procedure is used to approximate the profiles of drive-through commercial data with sources of interest present. This procedure
adds net-counts from a pre-defined set of simulated sources to raw, gross-count drive-through data randomly selected from
archived RPM data. The accuracy of the procedure — particularly the spatial distribution of the injected counts — has not
been fully examined. This report describes the use of previously constructed and validated MCNP computer models for assessing
the current injection-study procedure. In particular, this report focuses on the functions used to distribute the injected
counts throughout the raw drive-through spatial profiles, and for suggesting a new class of injection spatial distributions
that more closely resemble actual cargo scenarios.
Authors:S. Robinson, S. Bender, E. Flumerfelt, C. LoPresti, and M. Woodring
Time series of data from radiation portal monitors are evaluated for radioactive sources by comparing background to vehicle
spectra over time with a “spectral-distance” metric, isolating the contribution of anomalous radiation. This may diminish
systematic fluctuations from vehicular background attenuation and allow time-shape filtering for discriminating compact sources.
To examine this, a wavelet function similar in size to the expected source profile filters the spectral-distance output. Spectra
from chosen isotopes are injected into data from a U.S. port of entry. The resulting data are analyzed with gross-counting,
spectral-distance, and spatial algorithms. Combined spectral/spatial filtering is shown to enhance sensitivity and discrimination
of compact versus distributed sources.
Authors:L. Zhao, L. Robinson, R. Paul, R. Greenberg, and S. Miao
This paper describes the use of cold-neutron prompt-gamma activation analysis (CNPGAA) to determine carbon, nitrogen, and
phosphorus in the aquatic plant Typha domingensis, commonly known as cattail, during spring and fall seasons. According to studies of the Florida Everglades, cattail replaces
sawgrass as a result of nutrient enrichment from farm water runoff. Nutrient enrichment, especially phosphorus, in sediment
and the water column can lead to undesirable expansion. Early signs of this expansion are apparent in the Apalachicola River
floodplain near Apalachicola, Florida, USA. This research project is designed to use cattails as biomonitors of nutrient enrichment
in the lower Apalachicola River floodplain. Determination of carbon, nitrogen, and phosphorus in cattail using cold neutron
prompt-gamma activation has been developed in our previous studies at the CNPGAA facility at the National Institute of Standards
and Technology (NIST), USA. The results of numerous field samples, collected from the study area during spring and fall seasons
in 2002, will be presented in this paper.
Authors:L. Zhao, L. Robinson, R. L. Paul, R. R. Greenberg, and S. L. Miao
A method for the determination of carbon, nitrogen, and phosphorus in cattail using cold neutron prompt-gamma activation analysis (CNPGAA) has been developed and evaluated through the analysis of standard reference materials (SRM). After extensive preparation, approximately 400 mg cattail samples from the lower Apalachicola River floodplain were irradiated in the CNPGAA facility at the National Institute of Standards and Technology (NIST). The results of numerous field samples and two standard reference materials using the nuclear method show favorable comparison to results obtained by a CHNS/O analyzer.