A story about atomic ambition and a tragic fate

In the history of atomic research, few stories are as poignant or cautionary as that of the demonic core, a plutonium sphere designed for one of the most devastating weapons in history. This story not only encapsulates the highest point of atomic ambition, but also serves as a somber reminder of the human costs that come with such power.

At the center of this story are two scientists, Harry Daghlian and Louis Slotin, whose tragic fate is intertwined with the deadly properties of the core. Their story illustrates the fine line between groundbreaking science and great danger.

These two scientists’ experiences with the demon core reshaped the future of nuclear testing and safety protocols and marked a pivotal moment in the history of nuclear physics and occupational safety.

What is the demon core?

The demon core was a plutonium core, originally intended as the heart of the third atomic bomb developed by the United States during World War II. As the war neared its peak, the United States dropped two nuclear bombs on Japan – one on Hiroshima and another on Nagasaki – in an attempt to bring about a quick end to the conflict.

In the shadow of these monumental events, preparations were made for a possible third attack. The plutonium core, later infamously known as the ‘demon core’, was intended to power this third nuclear weapon.

The intention behind its creation was clear: if Japan did not surrender after the devastation at Hiroshima and Nagasaki, the US was prepared to drop a third atomic bomb to force submission.

However, history took a different turn. Japan’s surrender in the aftermath of the two atomic bombings put an end to the mounting and deployment of what would have been a third catastrophic event. Consequently, the demon core was never used as intended and remained at the Los Alamos National Laboratory, where it transitioned from a weapon of war to a subject of scientific research.

Despite its dormant state, the core retained a dangerous potential due to its critical mass: a precise amount of plutonium capable of sustaining a fission chain reaction.

This sustained capacity for unprecedented energy release made the demon core an object of both fascination and horror, and set the stage for a series of events that underscored the dangerous balance between scientific ambition and the sanctity of human life.

Who was Harry Daghlian?

Harry Daghlian was an American physicist who spearheaded United States atomic research into the Manhattan Project. He became an unconscious proof of the danger of handling radioactive material.

In the summer of 1945, Daghlian was involved in a critical experiment within the confines of the Los Alamos laboratory that was intended to test the limits of nuclear fission. His job was to construct a neutron reflector around the demon core to measure its approach to criticality (the point at which a nuclear chain reaction sustains itself).

Daghlian’s methodical approach saw him carefully assemble layers of tungsten carbide bricks around the plutonium core. He had built five layers of bricks and was about to place the last brick in the center when his measuring device indicated that the core could become supercritical.

The meeting was dangerously close to reaching critical mass.

In response to the warning, Daghlian attempted to withdraw the stone, aiming to stop the experiment and prevent the core from going critical. However, his hand slipped and he accidentally dropped the stone on the core. The accident immediately caused a critical reaction, manifested by a blue flash of light and a burst of heat.

How did Daghlian lose his life?

At that point, the plutonium bathed Daghlian in a lethal dose of radiation, marking the beginning of a painful battle against radiation sickness; Despite the efforts of medical professionals, Daghlian’s condition rapidly deteriorated and he ultimately died of radiation sickness 25 days later.

His tragic death highlighted the profound dangers inherent in the atomic age and served as a stark reminder of the power of the radioactive materials humanity had unleashed.

What does ‘critical’ mean?

The term ‘critical’ indicates a condition in which a nuclear chain reaction is self-sustaining. This criticality is reached when the mass of fissile material, such as plutonium or uranium, reaches a point where each nuclear fission releases a sufficient number of neutrons to sustain a continuous series of reactions.

Reaching critical mass does not necessarily mean a nuclear explosion is imminent; rather, it indicates that the material has achieved a delicate balance between neutron production and absorption. In controlled conditions, such as in a nuclear reactor, maintaining a critical state ensures a steady release of energy, useful for generating electricity.

Conversely, in the context of nuclear weapons, there is a deliberate attempt to exceed criticality – to move to what is known as ‘supercritical’ – to set off a rapid, uncontrolled chain reaction, resulting in a devastating nuclear explosion.

Playing with the sleeping dragon

Despite the tragic loss of Harry Daghlian, scientists at Los Alamos continued experiments on the core. Louis Slotin, a Canadian physicist known for his dexterity and confidence in handling radioactive materials, became the next to challenge the boundaries of nuclear physics.

Slotin was known for demonstrating a criticality experiment that pushed a plutonium core to the brink of criticality – essentially trying to get even closer to the brink of initiating an uncontrolled nuclear chain reaction.

The experiment used two beryllium-coated metal hemispheres, which could be brought close to the demon core to reflect neutrons back into it, making it critical.

The critical moment in the procedure came when Slotin, using only a screwdriver, wedged between the two spheres to create just enough space to prevent them from closing completely around the plutonium core: a risky process known as ‘tickling the tail of the sleeping dragon’. “

On May 21, 1946, Slotin demonstrated this precarious experiment to Alvin Graves, his intended replacement, and other scientists in the audience. As Slotin attempted the experiment, a slip of his hand caused the metal spheres to snap shut, instantly sending the core to its critical point.

The room was engulfed by another flash of blue light and a blast of heat, signifying a burst of neutron radiation.

Although Slotin quickly responded by removing the orb and stopping the reaction, the damage had already been done. The others in the room survived with varying degrees of radiation exposure, but Slotin was not so lucky. He received a massive dose of radiation poisoning and died nine days later, becoming the second victim of the demon core.

How many people died because of the demon core?

The demon core, a product of the Manhattan Project’s intense and groundbreaking efforts to harness atomic energy, claimed the lives of two physicists. The unfortunate victims, Harry Daghlian and Louis Slotin, suffered fatal accidents that led to their deaths due to acute radiation syndrome, also known as radiation sickness.

The deaths of Daghlian and Slotin were a stark reminder of the inherent risks associated with handling radioactive materials and encouraged the development of more stringent safety measures.

In response to these incidents, enhanced safety protocols, including remote control techniques and the implementation of strict critical safety guidelines, were adopted to prevent similar fatalities.

Although the demon core directly led to two deaths, its legacy led to significant advances in nuclear safety, ultimately safeguarding countless lives in the ensuing years of atomic research and energy production.

Does the demon core still exist?

The fate of the demon core, after its short but impressive history, would be melted down and recycled into new cores for testing.

After the second accident and the death of Louis Slotin, the laboratory brought about a change in the way it approached nuclear safety. Los Alamos recognized the dire consequences of hands-on criticality experiments and never again allowed its scientists to become involved in such dangerous direct contact.

In the wake of these reforms, remote criticality experiments were conducted at Los Alamos, separating scientists from radioactive material by about a quarter mile to ensure their safety.

This shift not only reflected a newfound respect for the power and danger of nuclear material, but also set a precedent for nuclear research worldwide. Because the US stopped dropping nuclear weapons after the bombings of Hiroshima and Nagasaki, the new cores made from the demon core remain unused.

We created this article using AI technology, then made sure it was fact-checked and edited by a HowStuffWorks editor.

Original article: The Demon Core: A Tale of Atomic Ambition and Tragic Fate

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