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The photodisintegration of the stable Lithium isotopes has been investigated by spectroscopy of the emitted charged particles using the Giessen bremsstrahlung facility. Protons, deuterons, tritons, 3He and alpha particles were detected and identified up to 20MeV particle energy. Angular distributions were measured using 7-ray energies up to E~. = 50 MeV. They are compared with theoretical predictions and with other experiments. A remarkable low (7, t)-cross section was found for both isotopes in disagreement to previous measurements using virtual photons. Coincidence measurements between the emitted particles were performed in order to study the manybody-breakups of 7Li.

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The O(y, po) reaction has been studied with linearly polarized bremsstrahlung photons in and below the giant E1 resonance. The parity of the absorbed radiation was determined from the observed azimuthal asymmetry of the emitted protons. Combined with unpolarized measurements the polarized results determine the proton decay amplitudes of the M1 resonance at E"=16. 2 MeV in O. The shape of the unpolarized O(y, p3) angular distribution in the giant E1 resonance was derived from the measured analyzing power. NUCLEAR REACTIONS ' O(y, p), E =15 -25 MeV; measured analyzing power 8 =90' linearly polarized bremsstrahlung; 0 dipole levels deduced m", 16.2 MeV1+ resonance deduced po decay amplitudes; 0 GEDR deduced p3 angular distribution. Investigations of photonuclear reactions with linearly polarized photons will become possible on a large scale in the near future. A monoenergetic almost completely polarized photon beam is available now at Frascati. ' The new generation of high duty factor electron accelerators presently under construction allow tagging the linearly polarized off-axis bremsstrahlung. Also the synchrotron radiation from the planned large electron positron storage ring LEP will be highly polarized and could be used for nuclear physics experiments. In this Communication we show that studies of photonuclear reactions with linearly polarized photons provide additional information about the excited nuclear states and their decay: (i) The parity of the absorbed radiation is determined in an unambiguous and completely model independent way. (ii) The decay amplitudes of overlapping resonances lith different parities can be separated.(iii) The (y, particle)-angular distribution for a dipole transition of known parity can be derived from a polarization measurement at only one angle. To exemplify this, we report here. on a study of the 'sO(y, pp) and "O(y, p3) reactions with linearly polarized bremsstrahlung photons in and below the region of the giant electric dipole resonance (GEDR).

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