Cygnus performance in subcritical experiments

Abstract

The Cygnus Dual Beam Radiographic Facility consists of two identical radiographic sources with the following specifications: 4-rad dose at 1 m, 1-mm spot size, 50-ns pulse length, 2.25-MeV endpoint energy. The facility is located in an underground tunnel complex at the Nevada Test Site. Here SubCritical Experiments (SCEs) are performed to study the dynamic properties of plutonium [1], [2]. The Cygnus sources were developed as a primary diagnostic for these tests. Since SCEs are single-shot, high-value events -reliability and reproducibility are key issues. Enhanced reliability involves minimization of failure modes through design, inspection, and testing. Many unique hardware and operational features were incorporated into Cygnus to insure reliability. Enhanced reproducibility involves normalization of shot-to-shot output also through design, inspection, and testing. The first SCE to utilize Cygnus, Armando, was executed on May 25, 2004. A year later, April -May 2005, calibrations using a plutonium step wedge were performed. The results from this series were used for more precise interpretation of the Armando data. In the period February -May 2007 Cygnus was fielded on Thermos, which is a series of small-sample plutonium shots using a one-dimensional geometry. Pulsed power research generally dictates frequent change in hardware configuration. Conversely, SCE applications have typically required constant machine settings. Therefore, while operating during the past four years we have accumulated a large database for evaluation of machine performance under highly consistent operating conditions. Through analysis of this database Cygnus reliability and reproducibility on Armando, Step Wedge, and Thermos is presented.

Lithium fluoride TLD dose quality

“…Shot-to-shot reproducibility of x-ray parameters is an important demonstration that source quality is consistent and that good radiography performance will likely be delivered on a crucial shot [2].…”

Option study of an orthogonal X-ray radiography axis for pRad at LANSCE area C, Los Alamos.

“…The Cygnus x-ray source is presently used to radiograph similar sized objects and line of site masses that are presently fielded in front of pRad. The Cygnus accelerators, located in the U1a drift at the Nevada Test Site (NTS), each drive a rod-pinch diode x-ray source which produce 4 Rad at 1-m from a ~1.0 mm diameter source [1][2][3][4][5].…”