Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

12C(γ,pn) photon asymmetry for Eγ = 180-340 MeV

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The photon asymmetry (Σ) of the 12C(γ→,pn) reaction has been measured using linearly polarised tagged photons at the Mainz microtron MAMI for Eγ = 180-340 MeV. The data have been analysed in separate missing energy (Em) regions corresponding to the ejection of nucleons from (1p)2 and (1p)(1s) shells. The measured Σ values for both Em regions are smaller in magnitude than corresponding 2H data, but the (1p)2 results have a similar Eγ dependence. Calculations of direct two-nucleon emission overestimate the magnitude of Σ at all photon energies. © 1999 Elsevier Science B.V. All rights reserved.