Los Alamos National Laboratory

Los Alamos National Laboratory

Delivering science and technology to protect our nation and promote world stability

Science of Signatures (SoS)

The Lab’s four Science Pillars harness our scientific capabilities for national security solutions.


Science of Signatures (SoS)


In its broadest and simplest sense, a “signature” is any information that is unique, recognizable, and useful. A handwritten mark as a means of demonstrating authenticity is a familiar example, as is the pattern variation that lets us distinguish spinach from poison ivy.

Phrased differently, signatures come from both raw signals and from information that can then be translated into knowledge.

One of four science pillars championed by Los Alamos National Laboratory, the Science of Signatures (SoS) applies our complete technological toolbox to solving intransigent problems in global security, nuclear defense, energy, and health.

SoS pillar strategy

The Laboratory’s scientific strategy is to discover new signatures, revolutionize the measurement of signatures, and engineer and deploy advanced signature-related technologies from the lab to the field.

Specifically, Los Alamos scientists

  • Characterize measures, signals, and properties in or of complex systems to detect or attribute change.
  • Predict systems behavior across scales in space (subatomic to astronomic) and time (femtosecond to geologic).
  • Assess impacts to the system of change.

Los Alamos areas of leadership in SoS

  • Nuclear and Radiological Signatures
  • Chemical and Materials Signatures
  • Biological Signatures
  • Energy Signatures
  • Climate Signatures
  • Space Signatures

Historical roots of the SoS pillar

Los Alamos can trace the roots of the Science of Signatures concept back to the Manhattan Project. One of the science challenges of that day was to understand how a nuclear device performed. Although the theoretical underpinnings of performance were understood, scientists still had many questions, including the following: 

  • How did that theoretical understanding conform to the experimental reality of the nuclear explosion?
  • What were the observables of value, or “signatures,” that would verify and validate the theory?
  • What were the prompt diagnostics (measurements in extreme conditions) that would give us information that would advance our ability to computationally model how the nuclear device worked?

Such questions spurred the development of a completely new area of science—that of nuclear signatures. It evolved from first principles directed at developing the tools required to understand nuclear weapon performance, first in atmospheric testing and then in the subsurface environment of the underground testing program. Many of today’s recognized nuclear signature techniques directly tie to the science that was developed at that time. The whole body of scientific knowledge that grew from these origins is foundational today to our stockpile stewardship mission of understanding nuclear weapons performance without testing. It is equally as important to our capabilities in nuclear and radiological forensics that have been and will be applied to understanding future nuclear events such as reactor accidents, rogue state nuclear activities, terrorist attacks, and more. No other scientific organization in the world has the breadth and depth of knowledge applicable to understanding these types of nuclear events.

The other five areas of Los Alamos leadership in the Science of Signatures had a similar genesis. Our chemical and materials signatures area of leadership grew from a need to understand the makeup and response of the materials in nuclear devices, then expanded as our mission broadened. Our biological signatures focus grew first from a need to understand the health effects of radiation and then expanded to include biosurveillance in the interests of national security. Signatures in space were a logical extension of our expansion into nonproliferation science and global security, and energy and climate signatures were folded in as we began to explore the national security science challenges implicit there as well.

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