Better-resolution measurement of vertical scattering angle in a new ion-optical mode of spectrometer 'Grand Raiden'

Demand for near-zero-degree measurements using a magnetic spectrometer is increasing with the growing interest in the study of L=0 nuclear excitation modes. For the precise determination of scattering angles near 0 deg., both horizontal and vertical scattering angle components have to be measured with good accuracy. It is, however, not easy to realize a good vertical angle resolution using modern high-resolution magnetic spectrometers with small vertical angle magnifications, like 'Grand Raiden' at RCNP or 'K600' at IUCF. A new ion-optical mode which enables the precise determination of vertical components of scattering angles from vertical position measurements in the focal plane has been developed for these spectrometers. For the wide range of spatial as well as momentum acceptances, vertical angle resolution better than 8 mrad is realized for Grand Raiden at RCNP