Number 56, November 15, 1991 by Phillip F. Schewe and Ben Stein DOPED FULLERENES ARE SUPERCONDUCTING AT 45 K. A collaboration of scientists from Allied Signal (Morristown, NJ), Arizona State, and Morris Research (Berkeley, CA) observed the new higher transition temperature in rubidium-thallium-doped samples of both C-60 and C-60/C-70 mixtures. (Z. Iqbal et al., Science, 8 November 1991.) A NEW MICRO-CANTILEVER MECHANICAL AMPLIFIER developed at the IBM Almaden Research Center magnifies the motion of a small test mass by up to a factor of 100, before the mechanical motion is converted into an equivalent electrical signal by a transducer. This results in an increased sensitivity in the measurement of small forces. IBM researchers Dan Rugar and P. Grütter believe that this improvement may aid atomic-force microscopy and gravitational-wave detection (Physical Review Letters, 5 August 1991). They also report being able to achieve, for the first time, "thermomechanical noise squeezing," a process---analogous to "squeezed light"---in which the thermal vibration (Brownian motion) of the micro-cantilever is reduced, at least in one phase, to a level substantially less than is usually allowed at room temperature. (Physics World, November 1991.) CARBON-13 DIAMONDS have the largest atomic density of any known solid. A General Electric/Ford collaboration led by William F. Bannholzer and Thomas R. Anthony at GE has studied the properties of synthetic diamonds with differing isotopic compositions, ranging from nearly-pure carbon-12 to nearly-pure carbon-13 (H. Holloway et al., Physical Review B, 1 October 1991). They found that the density of the C-13 diamonds was larger than that for natural diamonds by a factor of 0.04%, a smaller variation than had been expected from theoretical estimates. Practical applications of C-13 diamonds are unlikely unless the synthesis procedure, involving high pressures and temperatures, can be simplified. (Science, 1 Nov. 1991.) A HEAVY VERSION OF THE W BOSON , if it exists, must have a mass greater than 520 GeV/c2. Some versions of the Standard Model of particle interactions permit the possibility of such a particle, without specifying what its mass would be. (The W is one of the carriers of the weak nuclear force.) The Collider Detector at Fermilab (CDF) collaboration sought the W', as it is called, at energies up to 1.8 TeV, but found none, and can only specify a lower limit on its mass. (F. Abe et al., Physical Review Letters, 4 November 1991.) GRAPHITIC CARBON TUBES , up to a micron in length, have been made using the same arc-discharge techniques used to make buckyballs. Sumio Iijima of NEC Corporation in Japan observed that carbon needles growing on the negative electrode of the apparatus actually consisted of several (as many as 50) coaxial rolled-up sheets of carbon atoms in hexagonal arrays. Iijima believes that the formation of these needles may lead to other new carbon structures. (Nature, 7 November 1991.)