THE SUPERCONDUCTING TOROIDAL SPECTROMETER FOR HYPERNUCLEAR STUDIES ATKEK-PS

A spectrometer using a toroidal magnet with 12 superconducting coils w as constructed at the north experimental hall of the KEK 12 GeV proton synchrotron. The spectrometer comprised 12 individual sectors surroun ding the target point and served to measure pi(-) momentum for the pur pose of hypernuclear studies via the (stopped K-, pi(-)) reaction. A l arge solid angle of more than 6% x4 pi str was achieved in a wide mome ntum range between 180 and 350 MeV/c at the maximum 1.8 T magnetic exc itation, and in a range between 70 and 150 MeV/c at 0.65 T. A momentum resolution of 1.5 MeV/e FWHM was measured at 205 MeV/c, and a resolut ion around 3 MeV/c FWHM at 130-200 MeV/c was obtained including energy loss fluctuation in the experimental thick targets. (C) 1998 Elsevier Science B.V. All rights reserved.