Search

We present the first measurements of the gamma-ray beam energy resolution obtained with a new tagging system for the Ladon facility on the storage ring Adone at Frascati. A resolution of the order of 3% in the energy region of 30-80 MeV is obtained in accordance with predictions.

Measurement of the asymmetry factor in D(γ, np) is reported and the result is discussed in the framework of Partovi’s theory.

The reaction $^{2}(\ensuremath{\gamma}$,p)n has been studied using a monochromatic and polarized gamma ray beam at energies ${E}_{\ensuremath{\gamma}}$=19.8, 29.0, 38.6, and 60.8 MeV. The beam of an intensity \ensuremath{\sim}4\ifmmode\times\else\texttimes\fi{}${10}^{5}$ \ensuremath{\gamma}/sec was obtained by Compton back scattering of mode-locked laser light off electron bunches in the Adone storage ring. Photoneutron yields were measured at nine neutron angles ${\mathrm{theta}}_{\mathrm{n}\mathrm{\ensuremath{\simeq}}}$15, 30, 45, 60, 90, 120, 135, 150, and 165 deg in the center of mass (c.m.) for ${E}_{\ensuremath{\gamma}}$=19.8, 29.0, and 38.6 MeV, and at ${\mathrm{theta}}_{\mathrm{n}\mathrm{\ensuremath{\simeq}}}$30, 60, 90, 120, and 150 deg c.m. for ${E}_{\ensuremath{\gamma}}$=60.8 MeV. The polarization independent component ${I}_{0}$(theta) of the differential cross section and the polarization dependent component ${\mathrm{PI}}_{1}$(theta) were deduced and the angular distribution of the azimuthal asymmetry factor \ensuremath{\Sigma}(theta)=${I}_{1}$(theta)/${I}_{0}$(theta) was obtained. An extensive comparison with theory has been carried out and the inclusion of corrections due to meson exchange currents and to \ensuremath{\Delta}-isobar configurations have been shown to be mandatory at energies ${E}_{\ensuremath{\gamma}}$\ensuremath{\gtrsim}40 MeV. Theoretical and experimental implications of intermediate energy deuteron photo- disintegration studies are discussed in some detail.

The asymmetries ..sigma..(theta/sub c.m./ = ..pi../2) for the /sup 2/H(..gamma..,n)p reaction have been measured with use of the monochromatic and linearly polarized ..gamma..-ray beam (LADON), obtained by backward Compton scattering of laser light against high-energy electrons. Contributions from meson exchange currents must be included in the theoretical calculations to reproduce our data.