We report mu SR experiments on single-walled carbon nanotubes (SWnT). We fi
nd that injected muons form vacuum-like muonium (Mu) with a large probabili
ty ( similar to 40%). We discuss the temperature (T) dependence of the tran
sverse field (TF) signal of the diamagnetic fraction as well as the longitu
dinal field (LF) signal of Mu. (C) 2000 Elsevier Science B.V. All rights re
served.