A positron lifetime spectroscopy apparatus, which utilizes an intense pulse
d positron beam generated by an electron linear accelerator, is presented.
Using this apparatus we can measure positron lifetime spectra with variable
energy, high count rate, wide measurable time range, and high peak-to-back
ground ratio. These features are suitable for surface and near-surface posi
tronium experiments. (C) 2000 Elsevier Science Ltd. All rights reserved.