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507 results on '"Smith, Alan R."'

1. Are there too many fern genera?

Author

Schuettpelz, Eric, Rouhan, Germinal, Pryer, Kathleen M, Rothfels, Carl J, Prado, Jefferson, Sundue, Michael A, Windham, Michael D, Moran, Robbin C, and Smith, Alan R

Subjects
Evolutionary Biology, Plant Biology
Published
2018

3. Cosmogenic-neutron activation of TeO2 and implications for neutrinoless double-beta decay experiments

Author

Wang, Barbara S., Norman, Eric B., Scielzo, Nicholas D., Smith, Alan R., Thomas, Keenan J., and Wender, Stephen A.

Subjects
Nuclear Experiment, Physics - Instrumentation and Detectors
Abstract

Flux-averaged cross sections for cosmogenic-neutron activation of natural tellurium were measured using a neutron beam containing neutrons of kinetic energies up to $\sim$800 MeV, and having an energy spectrum similar to that of cosmic-ray neutrons at sea-level. Analysis of the radioisotopes produced reveals that 110mAg will be a dominant contributor to the cosmogenic-activation background in experiments searching for neutrinoless double-beta decay of 130Te, such as CUORE and SNO+. An estimate of the cosmogenic-activation background in the CUORE experiment has been obtained using the results of this measurement and cross-section measurements of proton activation of tellurium. Additionally, the measured cross sections in this work are also compared with results from semi-empirical cross-section calculations., Comment: 11 pages, 5 figures

Published
2015
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4. Report on Gamma-Ray Analysis of Seaweed Samples from Naturespirit Herbs LLC

Author

Norman, Eric B., Thomas, Keenan, Guillaumon, Pedro, and Smith, Alan R.

Subjects
Nuclear Experiment, Physics - Instrumentation and Detectors
Abstract

Five seaweed samples from Naturespirit Herbs LLC were counted using low-background high-resolution gamma-ray detectors to search for evidence of contamination from the Fukushima reactor accident. No evidence of Cs-134 was observed in any of the samples. Very low levels of Cs-137 were observed and are attributed to fallout from atmospheric nuclear weapons testing. However, these levels of Cs-137 are small compared to the levels of the naturally occurring K-40 observed from these seaweed samples.

Published
2014

5. Production of high purity TeO2 single crystals for the study of neutrinoless double beta decay

Author

Arnaboldi, C., Brofferio, C., Bryant, A., Bucci, C., Canonica, L., Capelli, S., Carrettoni, M., Clemenza, M., Dafinei, I., Di Domizio, S., Ferroni, F., Fiorini, E., Ge, Z., Giachero, A., Gironi, L., Giuliani, A., Gorla, P., Guardincerri, E., Kadel, R., Kazkaz, K., Kogler, L., Kolomensky, Y., Larsen, J., Laubenstein, M., Li, Y., Maiano, C., Martinez, M., Maruyama, R., Nisi, S., Nones, C., Norman, Eric B., Nucciotti, A., Orio, F., Pattavina, L., Pavan, M., Pessina, G., Pirro, S., Previtali, E., Rusconi, C., Scielzo, Nicholas D., Sisti, M., Smith, Alan R., Tian, W., Vignati, M., Wang, H., and Zhu, Y.

Subjects
Condensed Matter - Materials Science, Nuclear Experiment, Physics - Instrumentation and Detectors
Abstract

High purity TeO2 crystals are produced to be used for the search for the neutrinoless double beta decay of 130Te. Dedicated production lines for raw material synthesis, crystal growth and surface processing were built compliant with radio-purity constraints specific to rare event physics experiments. High sensitivity measurements of radio-isotope concentrations in raw materials, reactants, consumables, ancillaries and intermediary products used for TeO2 crystals production are reported. Production and certification protocols are presented and resulting ready-to-use TeO2 crystals are described., Comment: 11 pages, 5 figures, 3 tables

Published
2010
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16. A new species of Thelypteris (Thelypteridaceae) from southern Bahia, Brazil

Author

Matos, Fernando B., Smith, Alan R., and Labiak, Paulo H.

Subjects
Life Sciences, Plant Ecology, Plant Physiology, Plant Anatomy/Development, Plant Systematics/Taxonomy/Biogeography, Plant Sciences, Atlantic Rain Forest, ferns, Goniopteris, taxonomy, Thelypteris beckeriana
Abstract

A new species, Thelypteris beckeriana (Thelypteridaceae), is here described. It belongs to subgenus Goniopteris because of the presence of forked and stellate hairs on some parts of its blades. It is a narrow endemic to the Atlantic Rain Forest of southern Bahia, Brazil. A complete description, illustrations, and comparisons with the most similar species are provided.

Published
2010

24. A reappraisal of the reported dose equivalents at the boundary of the University of California Radiation Laboratory during the early days of Bevatron operation

Author

Thomas, Ralph H., Smith, Alan R., and Zeman, Gary H.

Subjects
Radiation protection and dosimetry, Bevatron neutron dosimetry environmental radiation
Abstract

Accelerator-produced radiation levels at the perimeter of the Ernest Orlando Lawrence Berkeley National Laboratory (the Berkeley Laboratory) reached a maximum in 1959. Neutrons produced by the Bevatron were the dominant component of the radiation field. Radiation levels were estimated from measurements of total neutron fluence and reported in units of dose equivalent (rem). Accurate conversion from total fluence to dose equivalent demands knowledge of both the energy spectrum of accelerator-produced neutrons and the appropriate conversion coefficient functions for different irradiation geometries. At that time (circa 1960), such information was limited, and it was necessary to use judgment in the interpretation of measured data. The Health Physics Group of the Berkeley Laboratory used the best data then available and, as a matter of policy, reported the most conservative (largest) values of dose equivalent supported by their data.Since the early sixties, significant improvements in the information required to compute dose equivalent, particularly in the case of conversion coefficients, have been reported in the scientific literature. This paper reinterprets the older neutron measurements using the best conversion coefficient data available today. It is concluded that the dose equivalents reported in the early sixties would be reduced by at least a factor of two using current methods of analysis.

Published
2008

35. Measurement of cross sections for the 63Cu(alpha,gamma)67Ga reaction from 5.9-8.7 MeV

Author

Basunia, M. Shamsuzzoha, Norman, Eric B., Shugart, Howard A., Smith, Alan R., Dolinski, Michelle J., and Quiter, Brian J.

Subjects
Nuclear physics and radiation physics, nucleosynthesis cross section alpha capture nuclear reaction
Abstract

We have measured cross sections for the 63Cu(alpha,gamma)67Ga reaction in the 5.9-8.7 MeV energy range using an activation technique. Natural Cu foils were bombarded with alpha beams from the 88 Cyclotron at Lawrence Berkeley National Laboratory (LBNL). Activated foils were counted using gamma spectrometry system at LBNL's Low Background Facility. The 63Cu(alpha,gamma)67Ga cross-sections were determined and compared with the latest NON-SMOKER theoretical values. Experimental cross sections were found to be in agreement with theoretical values.

Published
2004

37. Signatures of special nuclear material: High-energy gamma rays followi ng fission

Author

Norman, Eric B., Prussin, Stanley G., Larimer, Ruth-Mary, Shugart, Howard, Browne, Edgardo, Smith, Alan R., McDonald, Rchard J., Nitsche, Heino, Gupta, Puja, Frank, Michael I., and Gosnell, Thomas B.

Subjects
Nuclear disarmament, safeguards, and physical protection, Nuclear physics and radiation physics
Published
2003

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