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Stange, Sy

Publications and source records attributed to Stange, Sy.

Comparison of Fast Neutron Detector Technologies

This report documents the work performed for the Department of Homeland Security Domestic Nuclear Detection O ce as the project Fast Neutron Detection Evaluation under contract HSHQDC-14-X-00022. This study was performed as a follow-on to the project Study of Fast Neutron Signatures and Measurement Techniques for SNM Detection - DNDO CFP11-100 STA-01. That work compared various detector technologies in a portal monitor con guration, focusing on a comparison between a number of fast neutron detection techniques and two standard thermal neutron detection technologies. The conclusions of the earlier work are contained in the report Comparison of Fast Neutron Detector Technologies. This work is designed to address questions raised about assumptions underlying the models built for the earlier project. To that end, liquid scintillators of two di erent sizes{ one a commercial, o -the-shelf (COTS) model of standard dimensions and the other a large, planer module{were characterized at Los Alamos National Laboratory. The results of those measurements were combined with the results of the earlier models to gain a more complete picture of the performance of liquid scintillator as a portal monitor technology.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Add-a-Source Analysis Method for Neutron Coincidence Counting of Waste: Laboratory Exercises

In this session you will setup the INCC code to perform calibration and verification measurements on simulated waste drums using the Waste Drum Assay System (WDAS) detector, which uses the add-a-source (AAS) method. The basis of the AAS method is to measure the change in the counting rate from a small 252 Cf source (~3x10 4 n/s) located outside of the drum and to use this information to correct the count rate from material inside the drum for any changes caused by the matrix inside the drum. The count rate of the material inside the drum is corrected to the empty drum case so that only a single mass calibration curve has to be measured (for the empty drum configuration). In the WDAS system, the AAS neutron source has one location, centered beneath the waste drum. The sample matrix has two primary effects on the neutrons: (1) energy reduction by scattering reactions and (2) neutron absorption of the low-energy neutrons. In general, the counter is designed with an optimum moderator (CH 2 ) thickness to be relatively insensitive to the energy reduction; however, as the hydrogen density in the drum increases, the adsorption process significantly reduces the measured neutron signal.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗

Fast Neutron Detection Evaluation

These slides present a summary of previous work, conclusions, and anticipated schedule for the conclusion of our fast neutron detection evaluation.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗