RESEARCH 20 million times a second ~\v*»ll 1K»\OIU1 the limit of h u m a n hearing. They use a vibrating quartz crystal bonded to the crystal being studied. T h e acoustic absorption work at Westinghouse* was planned t o v e n h a theory b y Krench unci Russian researchers which predicted acoustic resonance nuclei. At the time. Westinghouse dkl not intend to develop a new technique lor crystal studies.
This model shows how nuclear magnetic resonance acoustic absorption works. T h e large coil generates a magnetic field around the small compasses—those on hlack tapes vibrate back and forth, compasses in between stand still. Vibration corresponds to the relative motion between nuclei caused by acoustic vibra tion of the crystal. T h e moving needles create a fluctuating magnetic field, causing resonance when the acoustic vibration settles on the right frequency
Atom Shaking Shows Structure Newly developed method extends use of nuclear magnetic resonance to metals and semiconductors NT iCLKvit magnetic resonance contin ues to broaden its usefulness as a re search tool. The latest variation is called Ν MR acoustic absorption. De veloped at Westinghouse, NMRAA probes the internal structure of crystal line materials by shaking atoms back and forth u p to 20 million times a sec ond. Westinghouse physicists believe the method is a major advance in studies of crystalline matter. They saxit opens a new field of research since it allows them to study crystals not studied before—particularly crystals of metals and semiconductor materials. Atomic nuclei resemble tiny spinning magnets. Such magnets have north a n d south poles which tend to line up parallel with one another when placed in a magnetic field. When these nuclei are shaken, enough energy is created to upset magnetic balance. XMR will detect this imbalance and show the in teraction between atomic nuclei and the electrons which swarm around them. • Differs from Straight NMR. West inghouse physicists D. I. Bolef and Meir Menés explain the difference between X\1R acoustic absorption and conventional XMR this way: A steady mag42
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m tic field will align nuclear magnets. But in so doing, the nuclear magnets start to wobble, or precess, somewhat the same way that a compass needle will oscillate when first placed in a strong magnetic field. In conventional XMR. a second magnetic field—pulsating instead of s t e a d y is applied at right angles to the steady field and the frequency is adjusted until it matches exactly the rate at which the nuclear magnets wobble. So adjusted, the nuclear magnets will absorb energy. This provides electrical signals to determine the internal structure of the material under question. However, Bolef and Menés point out this method does not work for crystal studies of metals and semiconductors. The pulsating magnetic field cannot penetrate such materials. But if a crystal is vibrated rapidly, magnetic and electrical fields are created which interact with nuclei. When the motion matches exactly· the frequency of wobble, the nuclei will behave exactly as they do when a pulsating external magnetic field is applied. Westinghouse creates nuclear shaking with sound waves that vibrate u p to
• PAS-Tebamin ( phmv Î pr/ra-aminosalicylic acid ). a new drug for the treatment of pulmonary tuberculosis, shows no incidence of gastro-intestiual disturbance, S . S. Cohen told the Sixth Annual Symposium o n Antibiotics. Other forms of PAS have limited use. he explains, because ol these side effects. • N i a g a r a Frontier's first nuclear research reactor—a 10()-kw. atomic reactor—will start operating at t h e Γ ι π λ π sity of Buffalo in July I960. Construc tion is under way now with grants of S425.00O from National Science Foun dation, S375,000 from local industr\. and $250,000 from National Institutes of Health. • Mental illness may be related to faulty blood chemistry. Merck Sharp & Dcilune researchers C. A. Winter and L. Flataker a r e investigating the frac tion of blood plasma containing the supposed toxic material. • Atlantic Research Corp. has devel oped a 72-poLind solid propellant rocket capable of lifting a 12-pound pavload 200.000 feet, will begin tests' this month. The rocket, ARCAS, is six feet long, 4.5 inches in diameter, lias a sepa ration device which ejects a nose cone and parachute assembly at flight's end. Rocket will b e used for atmospheric research by colleges and universities. • The Air Force a n d RIAS ( a research lab sponsored by Martin) are jointly studying the heavy components of cos mic radiation (a hindrance to space travel). The team is trying to learn more about the radiation belt which exists a few hundred miles above earth's surface. To augment the program. RIAS has developed a double ioniza tion chamber which differentiates the components of cosmic radiation from components of other types of radiation.
