In recent years

the study of more complicated hyperfine interactions

such as impurity-defect interaction in condensed matter

is rather interested. The partial amplitudes of some kind of specific perturbations are quite small as compared to the total. The exact extraction of them is difficult and depends critically on the characteristics of the spectrometere.g.differential linearity and time resolution.

A rotational triple detector system has been built for both in-beam and off-beam experiments.

The differential-nonlinearity in spectra is minimized through rotating the common start counter by 90° in successive measurement.

Some special electronic treatment has been taken and the total time resolution of the fast-slow circuit proves to be better than 1.5ns.