# How the Geiger Counter Detects Invisible Radiation

> A 1947 patent for a radiation detection device that uses a gas-filled tube to identify and count high-energy particles.

- **Patent:** US 2485586
- **Original title:** Geiger counter
- **Owner:** International Standard Electric Corp
- **Granted:** 1949
- **Status:** Public domain (expired)
- **Times cited:** 6
- **Field:** energy, mechanical, telecommunications

## What it does

The device functions by using a sealed tube filled with a specific gas at low pressure. When a radioactive particle enters the tube, it ionizes the gas, creating a brief electrical pulse between the electrodes. This pulse is then amplified and recorded as a 'click' or a numerical count, providing a direct measurement of radiation levels in the immediate environment.

## What it does NOT cover

- Does not cover solid-state radiation detectors like silicon diodes
- Does not cover scintillation counters that use light-emitting crystals
- Does not cover the fundamental physics of ionization itself
- Does not cover digital signal processing or modern computer-based data analysis

## The clever bit

The invention refined the gas-discharge mechanism to ensure that even a single ionizing event could trigger a measurable, distinct electrical pulse, effectively turning invisible radiation into audible or visual data.

## Real-world examples

1. Handheld radiation survey meters
2. Laboratory contamination monitors
3. Geiger-Muller tubes in nuclear research

## Why it matters

This technology was essential for the nuclear age, allowing scientists and workers to safely monitor radioactive materials. It became the standard tool for everything from geological surveying to medical safety and nuclear research.

## Frequently asked questions

### What does How the Geiger Counter Detects Invisible Radiation cover?

A 1947 patent for a radiation detection device that uses a gas-filled tube to identify and count high-energy particles.

### Who owns patent US 2485586?

International Standard Electric Corp owns this patent, granted in 1949.

### When does this patent expire?

This patent has expired and is now in the public domain — anyone can use the invention freely.

### What is patent US 2485586 cited by?

This patent has been cited by 6 later patents that build on its ideas.

### What problem does this patent solve?

This technology was essential for the nuclear age, allowing scientists and workers to safely monitor radioactive materials. It became the standard tool for everything from geological surveying to medical safety and nuclear research.

### What does this patent NOT cover?

Does not cover solid-state radiation detectors like silicon diodes

**Full plain-English explainer:** https://patentbrief.org/patent/us/2485586/geiger-counter

**Original patent:** https://patents.google.com/patent/US2485586

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_Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._


## Related patents

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- [How William Coolidge Invented the Modern X-Ray Tube](https://patentbrief.org/patent/us/1203495/coolidge-x-ray-tube) — A 1916 patent by William Coolidge for a high-vacuum X-ray tube that used a heated tungsten filament to control electron flow, replacing older, unreliable gas-filled tubes.
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- [How Ernest Lawrence Invented the Cyclotron Particle Accelerator](https://patentbrief.org/patent/us/1948384/cyclotron-lawrence) — This 1934 patent describes the cyclotron, a machine that uses magnetic and electric fields to whip particles into high speeds for scientific research.