Science: Particle Protection

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Every so often newspapers get steamed up about some mysterious new ray which will deal long-range death to men and animals, down airplanes or work other wholesale damage. Lately a ray said to stop gasoline engines and supposedly invented by no less a personage than Guglielmo Marconi stirred up a pother, which faded away when Marconi himself squelched it. Last week another exciting ray story cropped up in dispatches from Berkeley, Calif, which produced such headlines as NEW LETHAL RAY HURLED BY MAGNET, and NEW DEATH RAY TO AID MANKIND BEGINS ITS TEST.

The story concerned University of California's Ernest Orlando Lawrence, No. 1 U. S. experimenter in artificial radioactivity, whose 85-ton electromagnet frequently makes scientific news. Solemn young Dr. Lawrence would be horrified to find himself associated with the "death-rays"' of lurid pseudoscience. Actually he was only protecting himself and hi's co-workers from the effects of a beam of 10,000,000 neutrons a second generated with the help of his electromagnet for use in straightforward atomic experiments.

Dr. Lawrence has learned not to trifle with the big magnet. Once a small metal part worked loose within its field, whizzed into the core, nipped off the end of Dr. Lawrence's finger on the way. He and his men carry little gadgets resembling fountain pens clipped to their pockets, electroscopes to warn them of baneful radiations of the sort that set up tissue necrosis in x-ray experimenters. But neutrons, electrically inert particles, do not affect electroscopes, and penetrate many times farther than x-rays. Dr. Lawrence found that rats placed a few inches from the neutron source lost 80% of their white corpuscle blood count, and if exposure was prolonged the rats developed ulcers, died in two days.

This was the seed from which last week's fine death-ray story sprouted. Injury or death to small animals a few inches from the neutron beam's source was indeed a far cry from the pseudo-science reader's horrifying picture of deadly radiations capable of enflaming cities and wiping out their inhabitants at long range. Yet Dr. Lawrence's neutron beam, though designed only to harry atoms, is probably the nearest actual approach to the lethal ray of fiction. He decided therefore to take ample precautions. The control panel was moved 50 ft. from the beam and between them was interposed as a shield a three-foot wall of water the hydrogen in which is most effective in braking neutrons.