Radioactive Counting Clocks

We report on a radioactive counting clock (RCC) based on radioactive beta emissions from nickel-63 thin films. We present a theoretical analysis of the clock that uses the radioactive source (physics package) to lock and stabilize the frequency of a voltage-to-frequency converter (local oscillator). We present frequency stability measurements of the RCC over 10 days of clock operation. We analyze the limitations on the short-term and long-term frequency stabilities of the RCCs for use in design of clocks that require good frequency stabilities over long-term operations and consume low power, thus holding promise for use in timing and frequency applications in portable systems