  The linear coefficient of the radial thermal expansion has been measured on a
system of SWNT bundles in an interval of 2.2 - 120K. The measurement was
performed using a dilatometer with a sensitivity of 2*10-9 cm. The cylindrical
sample 7 mm high and 10 mm in diameter was obtained by compressing powder. The
resulting bundles of the nanotubes were oriented perpendicular to the sample
axis. The starting powder contained over 90% of SWNTs with the outer diameter
1.1 nm, the length varying within 5-30 um.
