Determination of the Triple Scattering Parameter R at 210 MeV

In connexion with a programme to determine thr p-p scattering matrix at 210 MeV, we have measured the rotation parameter R in a triple scattering experiment. Figure 1 shows the general layout of the experiment. The internal proton beam of the 130 in. synchrocyclotron is scattered at 15° from a carbon target (T₁). The scattered beam of about 215 MeV is 90 per cent polarized with the direction of polarization normal to the plane of the scattering. The beam is focused by a quadrupole lens and a deflection magnet to a beam spot at the position of the second target (T₂), 0^.95 in. wide, and 2^.2 in high (full width and height at half maximum). The liquid hydrogen target (T₂) consists of a cylinder, 5 in. in diameter with horizontal axis. The walls are 2 mil stainless steel. The outer vessel of the target has also thin stainless steel windows over the full extent oi the incident and the scattered proton beams. (author)