A LANL worker checks a laser diagnostic used on the Barolo subcritical experiment, conducted at the U1a test complex in Nevada in 2011.
The Nuclear Weapons Program at Los Alamos National Laboratory (LANL) conducts a wide range of experiments that generate vital data for the Stockpile Stewardship Program and the Laboratory’s global-security efforts.
Weapons-relevant experiments are now conducted at dozens of facilities across the nuclear weapons complex. These experiments range from small-scale tests designed to isolate a physics effect or measure a fundamental property of a particular material to full-scale experiments used to study the complex physics of implosions in realistic weapons configurations.
The Barolo subcritical experiments were conducted underground at the U1a complex, a vast warren of tunnels deep beneath the desert. These tests are called “subcritical” because they use fissile materials but create no self-sustaining nuclear chain reaction. Most subcritical tests employ plutonium which is imploded with high explosives or shocked in various ways1.
Image credit: Los Alamos National Laboratory