m u meson c a m e to rest it did not d e cay; rather, i t flung o u t another particle t h a t also looked like a m u , went a short distance, came to rest, a n d d e cayed. Some photographs showed a g a p between t h e t w o mu-like tracks, Alvarez told t h e American Physical Society meeting at Monterery, Calif. At first t h e group speculated a n e w particle, a "super-mu" w a s decaying into a n ordinary mu. After 15 of these events, the Alvarez group came u p with another explanation: W h e n t h e negative m u comes t o rest it becomes a t t a c h e d to a proton, forming a " m u mesic atom" sirnilar to, b u t m u c h smaller, than an ordinary atom. T h e m u meson is known to prefer to form a n atom w i t h a heavy particle at its center, so it selects t h e deuterons prese n t in the hydrogen. Any m u mesic atom will eventually attach itself to a n o t h e r atom to form a molecule. Alvarez explains the gaps in the tracks in this way: The original meson first forms a mesic atom with a proton. However, a mu meson will jump t o a deuteron if one is available. When this exchange occurs, the new deuteron mesic atom will drift away from the exchange point. T h e drift of t h e neutral mesic atom accounts for the g a p . At t h e e n d of t h e gap, the deuteron mesic atom combines with a proton and the nuclear reaction takes place. Since the m u meson speeds t h e reaction but i s not used u p , the term "catalyzed nuclear reaction" i s applied. T h e result of these processes r says Thermonuclear-like reaction points to possibilities for Alvarez, is that shordy after a mu comes to rest in hydrogen it finds itbetter kind of nuclear energy self holding a deuteron and a proton, which fuse to form helium-3. The mass of helium-3 i s less than that of a ported evidence for such a particle.) Jt4 ISSION c a n malce a ^ a i n reaction take place, as c a n fusion. T o these Also the reaction takes place at a n y proton a n d deuteron; t h e difference— temperature, while thermonuclear re- 5.4 million volts—is released as energy. two, scientists at University of CaliT o test its hypothesis, the U C group fornia Radiation Laboratory have actions take place only when nuclei a r e a d d e d concentrated deuterium to the added a rJhird: a "catalyzed nuclear propelled together b y great heat. • Getting Together. To make a natural deuterium in t h e bubble chamreaction," a. reaction that yields energy nuclear reaction take place, two nuclei ber, which increased t h e occurrence of and is a k i n to fusion (thermonuclear) an ejected mu or a gap at t h e e n d of must touch. T h e new reaction accomreactions. a mu. plishes this in a "mesic molecule." Luis W". Alvarez, leader of the 12The nuclei of atoms in a normal man team who took part i n the remolecule a r e pulled together weakly search, s a y s that at the present time by electrons. A much heavier particle, Testing Iron Whiskers the energy-produLcing reaction is only the negative m u meson, substituted a laboratory phenomenon because: for the electron will circle t h e nucleus New Westinghouse method • The cliain reaction cannot continue at a much shorter distance, thus bindfor determining tensile long enough to generate commercially ing the nuclei correspondingly closer. strength o f pure iron has acuseful amounts of power. Alvarez estimates that ordinary molecuracy of 0 . 1 % cules form a "box" the volume of which • The m u mesons which catalyze the is 10 million times larger than the reaction c a n be made only in highmesic molecule. JT\L?S IMPROVED M E T H O D of determining energy collisions of pairticles accelerObservations of the n e w reaction the tensile strength of iron whiskers ated by cyclotrons and cither expensive were m a d e in UC's bubble chamber; has been developed b y Westinghouse. machines . boiling liquid hydrogen forms bubbles These whiskers a r e highly purified iron However, Alvarez still believes the along t h e track of a charged particle crystals grown a s nearly perfect i n reaction lias possibilities if a much passing through it. T h e Berkeley structme as possible. Those produced longer lived particle (the mu meson de- group thought that all m u mesons that by Westinghouse are about 0.00004: cays after 0.000002 second) with propinch in diameter. The average whisker came to rest in hydrogen would just deerties similar to the Bin meson were cay, b u t soon it noticed that occasioncan be pulled a p a r t with a force of less found. ( A Russian physicist h a s re- ally when a particle that looked like a than 0.01 ounce.
RESEARCH
Energy Via Catalyzed Nuclear Reactions
N e w Nuclear Reaction
22
C&EN
JAN. I*,
1957
Γ* Ϋ
W o u l d Ben Franklin h a v e settled for less than D r . F r a n k l i n h a d a simple b u t effective m e t h o d for wringing t h e last d r o p of b u y i n g p o w e r o u t of a b u d g e t dollar. H e w r o t e down all the advantages and d i s a d v a n t a g e s of t a k i n g a certain action. W i t h all t h e frets in front of him, h e was s u r e t o m a k e the right decision. S h o u l d D r . Franklin b e b u y i n g labware t o d a y , his list o n P Y R E X brand might well l o o k l i k e this:
Advantages of PYREX labware 1. Less, much less, breakage. Shows heavier construc tion, especially at joints, lips, and other stress points. Next two properties save breakage too. 2. Takes heat, sudden temperature changes. I can sub ject this glassware to sudden temperature changes with out damaging it. Its coefficient of expansion is only 0.OO00O33 per ° C. between 0° and 300° C. 3. Chemically stable. PYREX b r a n d labware resists a l most all common acids and alkalies. 4. No contamination. Contains no elements of the mag nesia-lime-zinc group. No heavy metals. Low alkali con tent. Result: N o contamination of contents even over long storage periods. 'nii^ewi
5. Complete line. Having all glassware made of exactly the same glass gives me better test control. I can get all the different glassware I'll ever need with this
