Search

The first measurements of f(LT)’ known as the fifth response function, have been made for the H-2((e) over right arrow, e’p) and C-12((3) over right arrow, e’p) reactions. This response is directly related to the imaginary part of the interference between the transverse and longitudinal nuclear electromagnetic currents. Its observation requires longitudinally polarized electron beams and out-of-plane detection, the latter made possible by the newly developed out-of-plane spectrometer system. The initial measurements were made by using a 560-MeV polarized electron beam and quasielastic kinematics at Q(2) = 3.3 fm(-2). The development of the methodology for out-of-plane physics, and the analysis of the data from the initial experiments are described in detail. The measured fifth response and the related asymmetry in the coincidence cross section are in agreement, albeit with large statistical errors, with the theoretical predictions. Future extensions of the out-of-plane program are also discussed. [S0556-2813(99)02812-5].

We present a measurement of the induced proton polarization P-n in pi(0) electroproduction on the proton around the Delta resonance. The measurement was made at a central invariant mass and a squared four-momentum transfer of W=1231 MeV and Q(2)=0.126 GeV2/c(2), respectively. We measured a large induced polarization, P-n = -0.397 +/- 0.055 +/- 0.009. The data suggest that the scalar background is larger than expected from a recent effective Hamiltonian model. [S0556-2813(98)02012-3].