High resolution beam line for the Grand Raiden spectrometer

We have designed and constructed a new beam line which can accomplish both lateral and angular dispersion matching with the Grand Raiden spectrometer. In dispersive mode, lateral and angular dispersions of the beam line are b16 = 37.1 m and b26 = -20.0 rad, respectively, to satisfy matching conditions for Grand Raiden. In achromatic mode, the beam line satisfies the double achromatic condition of b16 = b26 = 0. The magnifications of the beam line are (Mx, My) = (-0.98, 0.89) and (-1.00, -0.99) for dispersive and achromatic modes, respectively. In the commissioning experiments, we have succeeded to separate the first excited 2+ state of 168Er with Ex = 79.8 keV clearly from the ground state in the (p, p′) reaction. We achieved energy resolutions of ΔE = 13.0 ± 0.3 and 16.7 ± 0.3 keV in full width at half-maximum for 295 and 392 MeV protons, respectively. These energy resolutions agree with the resolving power of Grand Raiden for an object size of about 1 mm. © 2002 Elsevier Science B.V. All rights reserved.