PERFORMANCE OF THE NEUTRON POLARIMETER NPOL2 FOR ((P)OVER-RIGHT-ARROW,(N)OVER-RIGHT-ARROW) POLARIZATION TRANSFER MEASUREMENTS

A high performance neutron polarimeter NPOL2 has been constructed to m easure polarization transfer observables D-ij for neutron kinetic ener gies of T-n = 150-400 MeV. The NPOL2 system consists of 6 planes of tw o-dimensional position-sensitive neutron detectors with a size of 1 x 1 x 0.1m(3). Neutron polarization is determined from the azimuthal dis tribution of the elastic (n) over bar + p scattering in the scintillat or material. The effective analyzing powers (A(y;eff)) of NPOL2 have b een calibrated by using the polarized neutrons from the 0 degrees H-2( (p) over right arrow,(n) over right arrow)pp reaction at T-p = 146, 22 8, 296, 346 and 392 MeV as well as by using the polarized neutrons fro m the 0 degrees Li-6((p) over right arrow,(n) over right arrow)Be-6(g. s.) reaction at T-p = 228 MeV. The A(y;eff) values of NPOL2 have reaso nable values, typically 0.223 +/- 0.012 and 0.132 +/- 0.004 for ((n) o ver right arrow>,n) and ((n) over right arrow p) channels, respectivel y, at T-n = 291 MeV. The figure-of-merit value defined as epsilon(D.S. )(A(y;eff))(2) is over 4 x 10(-4) for the wide neutron kinetic energy region of T-n = 200-400 MeV, where epsilon(D.S.) is the double scatter ing efficiency. (C) 1998 Elsevier Science B.V. All rights reserved.