Atomic Gadgets

Flash-Dater. Finding the age of ancient objects by radioactive Carbon 14 depends on supersensitive measuring apparatus. Professor Willard F. Libby, University of Chicago discoverer of Carbon 14 dating, uses a Geiger counter surrounded by a shield and other protections against intruding radiation. Chicago's Professor James R. Arnold announced last week an even more sensitive system.

The sample containing Carbon 14 (perhaps from a Sumerian tomb) is dissolved in a hydrocarbon fluid in a 4-in. tube. Radiation from its unstable atoms makes the liquid give flashes of light. They are too faint for human eyes to see, but photomultiplier tubes pick them up. The whole system is immersed in liquid mercury. As a further safeguard, the counting apparatus is adjusted so that it ignores all flashes of light too weak or too strong to come from Carbon 14.

Dr. Arnold's apparatus should extend the "Carbon 14 calendar" back from 23,000 to 42,000 B.C. and spot, within 37 years, the date, for instance, when slope-browed Neanderthal men roasted a wooly rhinoceros.

Beta Battery. Many radioactive isotopes give off energy continuously in the form of beta particles, i.e., high-speed electrons. Since an electric current is nothing but a flow of electrons, it has been obvious for years that a "beta emitter" might serve as the source of energy in a battery. How to build such a battery was not so obvious. If the electrons are merely collected like spent shot from a shotgun, most of their energy is lost.

Last week Radio Corp. of America demonstrated a sub-thimble-size radioactive battery that is somewhat more efficient. A film of Strontium 90 is spread on a wafer of silicon. When its beta particles shoot into the silicon, each of them releases 200,000 fresh electrons, which are collected as an electric current by a spot of silicon-antimony alloy.

The battery's strength (one millionth of a watt) is hardly one fly-power, and ninety-nine percent of the energy from the Strontium 90 is still wasted. But the battery is strong enough to work a transistor. RCA believes that its strength can be increased enough to make the battery useful. The Strontium 90 is durable; it loses only half of its power in 20 years.

Other atomic batteries have already found jobs. For two years, Radiation Research Corp. of West Palm Beach has been producing small quantities of "At-bee" batteries for radiation-detection instruments. The Atbee produces a smaller current at a higher voltage. It also gets its power from Strontium 90, and its producers say that its efficiency is the same. Unlike the RCAmen, they think it will be a long time before atomic batteries are used by the public.

This file is automatically generated by a robot program, so reader's discretion is required.