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COSMIC RAY BACKGROUND ANALYSIS FOR A CARGO CONTAINER COUNTER.

Description: We have developed a new model for calculating the expected yield of cosmic-ray spallation neutrons in a Cargo Container Counter, and we have benchmarked the model against measurements made with several existing large neutron counters. We also developed two versions of a new measurement uncertainty prediction code based on Microsoft Excel spreadsheets. The codes calculate the minimum detectability limit for the Cargo Container Counter for either neutron singles or doubles counting, and also propagate the uncertainties associated with efficiency normalization flux monitors and cosmic ray flux monitors. This paper will describe the physics basis for this analysis, and the results obtained for several different counter designs.
Date: January 1, 2001
Creator: Ensslin, Norbert; Geist, W. H. (William H.); Lestone, J. P. (John P.); Mayo, D. R. (Douglas R.) & Menlove, Howard O.
Partner: UNT Libraries Government Documents Department

An approach to multiplicity counting for a versatile new sensor for plutonium assay with a very short die-away time, and independent measurements of neutrons and gamma rays

Description: A unique detector design incorporating a {sup 6}Li-based capture medium, ZnS scintillator, and wavelength shifting optical fibers is the basis of a new neutron coincidence counter for measurements of plutonium in highly-impure residues. The sensor elements have a high efficiency for detecting neutrons and exhibit excellent gamma-ray discrimination based on pulse-shape analysis. The short die-away time of the counter that is based on these detector elements allows coincidence-gate settings shorter than 10 microseconds. This qualifies the technology for measurements of materials with high yields of uncorrelated neutrons from {sup 241}Am(alpha,n) reactions. The characteristics of the new neutron counter will be illustrated with test data from measurements of plutonium, {sup 252}Cf, and gamma-ray sources. The integrated electronics design of the new detector also permits the simultaneous but independent measurement of both neutrons and gamma rays. Recent test results that illustrate some unique applications of the sensor's versatility will also be presented.
Date: January 1, 2002
Creator: Belian, A. B. (Anthony B.); Browne, M. C. (Michael C.); Clay, W. A. (William A.); Geist, W. H. (William H.); Nguyen, H.; Ianakiev, K. D. et al.
Partner: UNT Libraries Government Documents Department

A versatile new sensor for Pu assay and independent measurements of neutrons and gamma rays

Description: A new well counter has been developed at Los Alamos National Laboratory that integrates the neutron capture medium (6LiF) and scintillator (ZnS) into a thin screen, which is coupled to wavelength shifting fiber-optic ribbon. A foursided prototype well counter has been built. It has a short neutron die-away time (t = 5.8 {micro}s), which increases its sensitivity to measurements of 240Pu by neutron coincidence counting. The neutron detection efficiency for this counter is 20%.
Date: January 1, 2002
Creator: Belian, A. P. (Anthony P.); Browne, M. C. (Michael C.); Clay, W. A. (William A.); Geist, W. H. (William H.); Nguyen, H.; Ianakiev, K. D. et al.
Partner: UNT Libraries Government Documents Department

Attribute measurement systems prototypes and equipment in the United States.

Description: Since the fall of 1997, the United States has been developing prototypical attribute verification technology for potential use by the International Atomic Energy Agency (IAEA) under the Trilateral Initiative. The first attribute measurement equipment demonstration took place in December 1997 at the Lawrence Livermore National Laboratory. This demonstration led to a series of joint Russian Federatioin/US/IAEA technical discussions that focused on attribute measurement technology that could be applied to plutonium bearing items having classified characteristics. A first prototype attribute verification system with an information barrier was demonstrated at a Trilateral Technical Workshop in June 1999 at Los Alamos. This prototype nourished further fruitful discussions between the three parties that has in turn led to the documents discussed in a previous paper. Prototype development has continued in the US, under other initiatives, using an integrated approach that includes the Trilatleral Initiative. Specifically for the Trilateral Initiative, US development has turned to some peripheral equipment that would support verifications by the IAEA. This equipment includes an authentication tool for measurement systems with information barriers and in situ probes that would facilitate inspections by reducing the need to move material out of storage locations for reverification. In this paper, we will first summarize the development of attribute verification measurement system technology in the US and then report on the status of the development of other equipment to support the Trilateral Initiative.
Date: January 1, 2001
Creator: Langner, D. C. (Diana C.); Landry, R. P. (Robert P.); Hsue, S.-T. (Sin-Tao); MacArthur, D. W. (Duncan W.); Mayo, D. R. (Douglas R.); Smith, M. K. (Morag K.) et al.
Partner: UNT Libraries Government Documents Department