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Origins, Visions, Plans & Wave Reactors

Teichert
SPEAKER:
CHRISTIAN TEICHERT
DATE/TIME:
MON, 04/25/2011 - 4:00PM TO 5:00PM
LOCATION:
3105 ETCHEVERRY HALL
Spring 2011 Colloquium Series
Abstract:

Low-energy ion irradiation of semiconductor surfaces [1] opens an elegant and efficient route towards fabrication of large-scale arrays of uniform semiconductor nanostructures. Using power spectral density analysis of atomic force microscopy (AFM) images, the degree of pattern uniformity can be quantified as is demonstrated for ion- bombardment induced GaSb dot arrays [2]. Attempts to obtain similar pattern formation by ion-bombardment of clean silicon substrates fail [3], unless there is a supply of metal impurities [4].

Since the ion-bombardment induced nanostructure arrays cover the entire sample surface, they can be used as large-area nanopatterned templates for subsequent deposition of magnetic thin films. This will be illustrated for the shadow deposition of cobalt onto ion-bombardment induced GaSb dot patterns. It will further be demonstrated how pre-ion bombardment can influence the resulting growth mode of organic semiconductor films [6]. Finally, it is shown that friction force microscopy and atomic-force microscopy can be employed to study single impacts of highly charged ions.

[1] S. Facsko, et. al., Science 285 (1999) 1551;
[2] T. Bobek, et al., Phys. Rev. B 68 (2003) 085324.
[3] C. Hofer, et al., Nucl. Instrum. Meth. B 216 (2004) 178.
[4] C. Teichert, et al., Adv. Eng. Mat. 8 (2006) 1057-1065.
[5] C. Teichert, et al., J. Cond. Mat. Phys. 21 (2009) 224025.
[6] G. Hlawacek, et al., Science. 321 (2008) 108.

This research has been supported in the framework of the European Project NAMASOS (Nanomagnets by Self-Organisation, Grant No. STRP 505854-1) and by Austrian Science Fund within NFN “Organic Thin Films” project S9707.

Video:

Webcast

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Treatment of Epistemic Uncertainty in Risk Analysis: Implications for Risk-Informed Decision-Making

Dana_Kelly
SPEAKER:
DANA KELLY
DATE/TIME:
MON, 04/18/2011 - 4:00PM TO 5:00PM
LOCATION:
3105 ETCHEVERRY HALL
Spring 2011 Colloquium Series
Abstract:

Quantitative risk assessments are an integral part of risk-informed regulation of current and future nuclear plants in the U.S. The Bayesian approach to uncertainty, in which both stochastic and epistemic uncertainties are represented with precise probability distributions, is the standard approach to modeling uncertainties in such quantitative risk assessments. However, there are long-standing criticisms of the Bayesian approach to epistemic uncertainty from many perspectives, and a number of alternative approaches have been proposed. Among these alternatives, the most promising (and most rapidly developing) would appear to be the concept of imprecise probability (Walley, 1991). In this colloquium, I will employ a performance indicatory example to focus the discussion. I will first give a short overview of the traditional Bayesian paradigm and review some its controversial aspects, for example, issues with so-called noninformative prior distributions. I then discuss how the imprecise probability approach handles these issues and compare it with two other approaches: sensitivity analysis and hierarchical Bayes modeling. I conclude with some practical implications for risk-informed decision making and an overview of ongoing research.

About the Speaker:

Dana Kelly is a Distinguished Staff Scientist in the Nuclear Risk and Reliability group at the Idaho National Laboratory. His current research focuses primarily on Bayesian and non-Bayesian approaches to uncertainty quantification, decision analysis, and simulation of complex systems. He has worked in the field of risk assessment for over 20 years and has numerous peer-reviewed publications in technical journals.

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The Spent Nuclear Fuel and Non-Proliferation

Bekhzod_Yuldashev

SPEAKER:
BEKHZOD YULDASHEV
DATE/TIME:
MON, 04/04/2011 - 4:00PM TO 5:00PM
LOCATION:
3105 ETCHEVERRY HALL
Spring 2011 Colloquium Series

Abstract:

The review of the activities on repatriation of highly enriched spent fuel from research reactors as well as data on the conversion of research reactors to low enriched fuel will be presented.

About the Speaker:

Professor Bekhzod Yuldashev is presently working as professor consultant at the Center for International Security and Cooperation ( CISAC) of Stanford University. From June 2006 till December 2009 he served as scientific consultant at International Atomic Energy Agency in Vienna (Austria). From 1990 till 2006 he was director general of the Institute of Nuclear Physics in Tashkent, Uzbekistan. He also served as president of Uzbekistan Academy of Sciences in 2000-2005.
He is a full member of Uzbekistan Academy of Sciences, Foreign Member of National Academy of Sciences of Kazakhstan, a Fellow of the World Academy of Sciences of Islamic Countries and some other scientific academies and societies. He is Honorary Doctor of the Joint Institute for Nuclear Research-JINR (Dubna, Russia), the Honorary Professor of Samarkand State University, was Visiting Fellow of Indiana University (Bloomington, USA) and Cambridge University (UK). He has been elected as a member of International Scientific Council of JINR (1992-2002), member of the Standing Advisory Group on Nuclear Applications, SAGNA (IAEA, Vienna, 2002-2006), the Chairman of Uzbekistan Scientific Council on Awarding doctoral ranks in nuclear sciences (1991-2006), head of Nuclear Department of Tashkent State University (1994-2000).

He is awarded by the State Prize in Science and Technology (1983), the Science and Technology ECO International Prize (2004), the order “For Glorious Work” (Uzbekistan, 2003) etc.

Professor Bekhzod Yuldashev graduated from Tashkent and Moscow universities (1968) and got his Candidate Degree ( PhD) in 1971 at JINR and Full Professor degree (Doctor of Physics and Mathematics) in 1981. He was spokesman of two experiments performed at Fermi National Laboratory (Batavia, US) and at Canadian nuclear center “TRIUMF” (Vancouver BC) by two international teams involving physicists from Uzbekistan, Russia, US and Canada. In 1977-1978, 1980-1981 and 1989-1990 he was visiting professor at Physics Department of University of Washington (Seattle, USA) and in 2007 at CISAC, Stanford University (Stanford, USA).

His research covered particle and nuclear physics and nuclear applications. He published more than 200 papers and has more than 20 patents. He was scientific supervisor of 27 PhD and 6 Full Professor theses.

In last 15 years Professor Yuldashev is deeply involved in non-proliferation and nuclear applications projects. In particular, he led projects on upgrading physical protection of research reactors, on utilization of highly radioactive sources, development of systems to prevent illicit trafficking of nuclear and radioactive materials, the conversion of research reactors to low enriched fuel, the return of highly enriched spent fuel from research reactors to country-origin. Being consultant at IAEA Professor Yuldashev was working on performance of Russian Research Reactor Spent Fuel Return Program and wrote the IAEA technical book on lessons learned from shipments of highly enriched spent fuel from research reactors to country-origin.