Enhancement of persistent currents in Bi₂Sr₂CaCu ₂O₈ tapes with splayed columnar defects induced with 0.8 GeV protons

Composite tapes of the superconductor Bi2Sr2CaCu 2O8 on silver were irradiated with energetic light ions (0.8 GeV protons), creating extended splayed tracks ∼7 nm in diameter via fission of Bi nuclei. Magnetic hysteresis indicates large enhancements of persistent currents J, especially at high fields and temperatures, and substantial expansion of the irreversible regime. The technique may be suitable for large scale applications due to the long range (∼half meter) of fast protons.