Electronically focused time-of-flight powder diffractometers at the intense pulsed neutron source

Two time-of-flight powder diffractometers have operated at the Intense Pulsed Neutron Source (IPNS) since August 1981. These instruments use dedicated microcomputers to focus time-of-flight events so that data from different detectors can be summed into a single histogram. Thus, large multidetector arrays can be employed at any scattering angle from 12 to 157°. This design permits data to be collected over a uniquely wide range of d spacings while maintaining high resolution and count rates. The performance of the two instruments is evaluated by analyzing data from a standard Al₂O₃ sample by the Rietveld method. These instruments provide the capability for moderate- to high-resolution measurements with the duration of a typical run being a few hours.