Scintillation dynamic spectra and transverse velocities of seven pulsars

Using a pulsar timing system developed at Urumqi Astronomical Observatory's 25-m telescope, we observed scintillation dynamic spectra for seven pulsar s at the relatively high frequency of 1540 MHz over a wide frequency band o f 320 MHz. Averaging observations at different epochs, we obtain time scale s and decorrelation bandwidths for diffractive scintillation and show that these imply a power-law index for the electron density fluctuation close to 4.0. Assuming this value and that the scattering disk is approximately mid way between the pulsar and the earth, we complete transverse velocities for the seven pulsars. These values are generally in good agreement with the p roper motion velocities.