Target structure and in-beam electron spectra

The main features of the interplay between the target structure and the accelerated ion beam characteristics suitable for an in-beam e-gamma measurement are discussed in detail. In particular, the different types of ''spurious'' electron (and photon) spectra overlapped with in-beam internal conversion electrons (and discrete gamma-rays) are reviewed as well as the most efficient experimental methods used for their attenuation. Furthermore, the general characteristics of particle beams, targets and electron spectrometers required for prompt and delayed in-beam e, gamma and e-gamma measurements are also compared. Moreover, the relative magnitude of the electron line Doppler broadening corresponding to the perpendicular and the collinear geometry is briefly discussed and illustrated by a few in-beam e-gamma studies of Pm and Eu isotopes produced by accelerated ions (H-2(1) and Li-7(3)) bombarding very thin Nd(+C) backed targets. Finally the most recent developments made at Orsay towards multi e-gamma detector assemblies lead to a broad discussion concerning the most suitable targets to be inserted within such instrumental arrangements.