Out-of-plane measurements of the fifth response function of the exclusive electronuclear response - art. no. 064622

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 a rrow, e'p) reactions. This response is directly related to the imaginary pa rt of the interference between the transverse and longitudinal nuclear elec tromagnetic currents. Its observation requires longitudinally polarized ele ctron beams and out-of-plane detection, the latter made possible by the new ly developed out-of-plane spectrometer system. The initial measurements wer e made by using a 560-MeV polarized electron beam and quasielastic kinemati cs at Q(2) = 3.3 fm(-2). The development of the methodology for out-of-plan e physics, and the analysis of the data from the initial experiments are de scribed in detail. The measured fifth response and the related asymmetry in the coincidence cross section are in agreement, albeit with large statisti cal errors, with the theoretical predictions. Future extensions of the out- of-plane program are also discussed. [S0556-2813(99)02812-5].