Demon Core Incident video

In the world of nuclear physics, the pursuit of knowledge and technological advancement has sometimes come at a terrible cost. The Demon Core incident, which occurred in 1946 at a secret laboratory in Los Alamos, New Mexico, stands as a chilling reminder of the dangers associated with nuclear experimentation. In this article, we will delve into the details of this tragic event and explore its lasting impact on the scientific community and beyond.

Demon Core Incident Video
Demon Core Incident Video

The Fateful Experiment

The Demon Core and Its Purpose

At the heart of this incident was the Demon Core, a 14-pound metallic sphere of plutonium intended for use in a nuclear bomb.

Scientists at Los Alamos were working with this core as part of the Manhattan Project, the United States’ nuclear weapon development effort during World War II.

Louis Slotin and the Critical Demonstration

On May 21, 1946, Canadian physicist Louis Slotin was conducting a demonstration to show how the exposed core of a nuclear weapon could be brought close to criticality.

The demonstration involved using a half-shell of beryllium, called the tamper, to reflect neutrons emitted by the plutonium back into the core, initiating a weak nuclear chain reaction.

The Screwdriver Slip

Slotin held the tamper in his left hand and a long screwdriver in his right hand, which he intended to wedge between the tamper and the core to keep them apart. However, a tragic mishap occurred when Slotin’s screwdriver slipped, causing the tamper to drop fully over the core.

The Screwdriver Slip
The Screwdriver Slip

The Blue Flash and Heat Wave

The moment the tamper fully covered the core, a bright blue flash of light and a wave of heat erupted from the assembly. This indicated that the core had gone critical, reaching a state where it could sustain a chain reaction. Subsequent calculations estimated that about three quadrillion fission reactions had taken place in that instant.

The Aftermath and Evacuation

Immediately following the incident, Slotin and his colleagues were evacuated from the lab, and an ambulance was called. Slotin attempted to assess the radiation levels using a detector, but the heavy contamination made it difficult to obtain accurate readings.

Body PartRadiation Dose
Left HandHigh
Whole BodySignificant

Slotin’s left hand, which had been closest to the core, received a high dose of radiation, resulting in severe burns and blisters. His whole-body dose was also significant, putting him at risk for acute radiation syndrome.

The Tragic Consequences

The Tragic Consequences
The Tragic Consequences

Slotin’s Rapid Health Decline

Despite receiving medical attention, Slotin’s health rapidly deteriorated in the days following the incident. He experienced a range of distressing symptoms:

  • Nausea
  • Abdominal pain
  • Weight loss
  • Mental confusion

The Fatal Outcome

Nine days after the incident, Louis Slotin tragically succumbed to acute radiation syndrome, also known as radiation sickness. His death served as a stark reminder of the immense risks associated with working with nuclear materials.

The Second Fatality

Tragically, Slotin was not the only casualty of the Demon Core. Just months earlier, in August 1945, another physicist named Harry Daghlian had been exposed to a lethal dose of radiation from the same core during a separate experiment. Daghlian died 25 days after his exposure, making him the first known person to die from a criticality accident.

The Legacy of the Demon Core

The Legacy Of The Demon Core
The Legacy Of The Demon Core

Melted Down and Reintegrated

Despite the tragic loss of life, the Demon Core itself was not retired from use. Instead, it was melted down and reintegrated into the United States’ nuclear stockpile, serving as a haunting reminder of the sacrifices made in the pursuit of nuclear knowledge.

A Cautionary Tale

The Demon Core incident serves as a cautionary tale, highlighting the immense responsibilities and potential consequences that come with pushing the boundaries of scientific exploration. It underscores the need for the utmost caution, rigorous safety protocols, and a deep respect for the power of nuclear technology.

Honoring the Fallen

While the Demon Core itself may have been repurposed, the memory of Louis Slotin and Harry Daghlian lives on. Their tragic sacrifices serve as a somber reminder of the brave men and women who have dedicated their lives to the advancement of science, even in the face of great personal risk.


The Demon Core incident remains a haunting chapter in the history of nuclear physics, a stark reminder of the dangers that can arise when pushing the boundaries of scientific understanding. As we continue to explore the mysteries of the atomic world, let us never forget the lessons learned from this tragic event and the lives lost in the pursuit of knowledge. May the legacies of Louis Slotin and Harry Daghlian forever serve as a testament to the importance of safety, responsibility, and the enduring human spirit in the face of adversity.

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