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Explosive impacts on plutonium topic for Hixson's classified colloquium today

A 25-year veteran of Los Alamos research into the mysterious ways that explosive shock waves change plutonium will present the next Classified Director's Colloquium today.

Rob Hixson of Materials Dynamics (DX-2) will talk about "Dynamic Properties of Plutonium: Pioneering Research on an Enigmatic Metal" at 1:10 this afternoon in the Administration Building Auditorium at Technical Area 3.

Hixson plans to focus on a series of key experiments with plutonium over the past several years at the 40-millimeter gas gun at Technical Area 55.

"A lot of the previous theoretical and experimental work with plutonium has concentrated on how it behaves at ambient pressure," Hixson said. "These experiments at low, medium and high pressures have uncovered some real puzzles."

All attendees must be U.S nationals who hold "Q" clearances and have sigmas 1-10 assigned by line management.

The extraordinarily complex metallurgical, chemical and materials properties of plutonium have been the subject of a great deal of research. But Hixson said little was known about the dynamic properties of element 94 until the recent TA-55 gas gun experiments, subcritical experiments at the Nevada Test Site and other collaborations with Livermore, Sandia, Bechtel Nevada and the United Kingdom's Atomic Weapons Establishment.

"I'll summarize a lot of what we've learned so far, but as is often the case in pioneering research, many new questions have arisen and I'll try to explain some of these as well," Hixson said.

He also plans to propose elements of a path forward for additional plutonium research that will require new techniques and new diagnostics.

Hixson has been the lead experimentalist or principal investigator on many of the gas gun experiments and some of Los Alamos' subcritical experiments at NTS.

"The data and the new knowledge about plutonium that we've gained is the result of a tremendous effort by a lot of people out at TA-55 in the 1990s to obtain the necessary permissions to put energetic materials with plutonium into a glove box and operate the gas gun," Hixson said.

He came to what is now the Applied Physics (X) Division in 1980 and spent 18 months at NTS early in his career, then moved to the former Shockwave Physics (M-6) and has worked in that group or its successors ever since. Hixson was named a Laboratory Fellow in 2005.

He holds a bachelor's degree from California State University, Hayward, a master's from William and Mary and a doctoral degree from Washington State, all in physics.

The goal for the director's classified colloquium series is to disseminate important and interesting information on classified scientific topics to Los Alamos technical staff. The talks are planned to help inform a wide audience of Los Alamos' major classified scientific research and to stimulate discussions within an appropriate, secure environment, ultimately leading to future ideas and initiatives that will advance classified programs.

Transportation is available by calling 7-TAXI (7-8294) and indicating interest in attending the classified colloquium.

--Jim Danneskiold

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