Short-lived fission product measurements from &gt;0.1 MeV neutron-induced fission using boron carbide

Finn, Erin C.; Metz, Lori A.; Greenwood, Lawrence R.; Pierson, Bruce D.; Friese, Judah I.; Kephart, Rosara F.; Kephart, Jeremy D.

doi:10.1007/s10967-012-1652-y

Cited by 9 publications

(2 citation statements)

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“…They used analog-to-digital convertors to convert the collected charge signal from the preamplifier to a digital signal that could be processed and time-stamped for analysis after the count. Since then, fast digitizers in conjunction with HPGe detectors have been in use for a variety of projects including coincidence-summing event recovery [18], the discovery of 238 Th [19], and fission product measurements [20].…”

Section: Chapter 3: Literature Reviewmentioning

confidence: 99%

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Multispectral Gamma-Ray Analysis Using Clover Detectors with Application to Uranium Fission Product Analysis

Horne

Jackman

2013

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DedicationI would like to dedicate this work to my dear wife, Juliann, who has loved me unconditionally and supportively listened to my break-throughs, even when I didn't make sense. Supervisors: Sheldon Landsberger and Kevin Jackman Abstract: A high-efficiency gamma-ray counting system has been built at Los Alamos National Laboratory for use in analyzing nuclear forensics samples. This system consists of two clover high-purity germanium detectors and is surrounded by a thallium-doped sodium iodide annulus. Special precautions have been taken to ensure the system has a low background. The system is connected to XIA Pixie-4 fast digitizers and collects data in list-mode. This work is split into two main parts. The first part describes the proper steps and techniques to initialize the settings of a detector system connected to fast digitizers in order to optimize the system for resolution and throughput. The various counting modes for this particular system are described in detail, including the benefits and drawbacks of each mode. Steps are then shown to characterize the system by obtaining efficiency curves for various counting modes and sample geometries. Because of the close counting geometry involved with this system, truecoincidence summing factors must be calculated, and are done so in part by measuring the peak-to-total ratios of the system in its various counting modes across a wide energy range. The dead-time for the system can be complicated due to the multiple inputs of the system.Techniques for calculating the dead-time of multiple-detector systems are discussed. The second part of this work shows the system's usefulness in analyzing nuclear forensics samples, specifically irradiated enriched uranium. Three fission product parent-daughter pairs of different lifetimes are analyzed over a course of six months. The activities of each nuclide are calculated at each time step. Age dating techniques using the parent-daughter pairs are discussed, as well as the detection limits of each nuclide for a range of sample ages. Finally, vii avenues for further research are presented, as well as potential sources of error or uncertainty for this work.viii List of Tables Part 1: IntroductionThe analysis of nuclear materials, whether fresh or spent, using gamma spectroscopy is a commonly used technique which aims to gather pertinent information regarding the material's isotopic composition. Useful properties such as age, fission product activities, uranium enrichment information, and actinide activities may be determined by gamma spectroscopy. By understanding these properties, scientists and researchers can provide vital information to policy-makers and government officials (DOE, DoD, DHS, etc…) to aid in the nuclear forensics attribution process should a nuclear event occur.Traditionally, gamma spectroscopy research is done by using analog systems with a single detector. More recently, Compton suppression systems involving a single solid-state detector and one or more high-efficiency scintillation detectors op...

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Section: Chapter 3: Literature Reviewmentioning

confidence: 99%

“…Plugging in values for I 1836 and T 1 , we have and the P/T ratio of the 1836 keV gamma is 0.21925 (20) in Add Back mode. Using the equation for efficiency involving cascading gamma-ray emissions, the corrected efficiency for the 898 keV gamma becomes 0.152 (6).…”

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confidence: 96%