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Clock Timed by Radioactive Delay

IP.com Disclosure Number: IPCOM000084506D
Original Publication Date: 1975-Nov-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Gamblin, RL: AUTHOR

Abstract

The timing of this clock is determined by counting the number of particles emitted by a radioactive substance. The count will be independent of the environment.

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Clock Timed by Radioactive Delay

The timing of this clock is determined by counting the number of particles emitted by a radioactive substance. The count will be independent of the environment.

During the radioactive delay of a fixed mass of a substance such as americium 241, alpha particles are emitted at a slowly decreasing random rate. The total number of particles emitted by an initial (and, ultimately, decreasing) moderately large mass is very accurately calculable over the materials half-life. However, the number of particles emitted during shorter intervals is in error roughly as the square root of the number of particles emitted.

The circuit counts the number of particles emitted and steps a clock whenever that number equals a predetermined value. The predetermined value equals a measured particle-emission rate per second for the initial mass of the emitting substance. As the mass decreases, the predetermined value is also decreased. The detector senses particles from the source and supplies signals to an amplifier and pulse shaper, which provide a single pulse for each sensed particle. Each pulse increments a binary primary counter by one.

An initial predetermined binary value is placed in the interval register. The comparator provides a single pulse to a clock whenever a low-order portion of the binary value in the counter equals the value in the register. The counter is incremented after equality, until a value in pulses equal to the value in seconds f...