الفهرس 
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Abstract
The electron-photon -delayed coincidence technique was util¬ised for the first time in the present work, on calcium , to investigate the polarisation correlation between electrons inelastically scattered from calcium atoms with an energy loss of 2.9 eV and the photons emitted from subsequent decay of the 4’P state.These measurements were carried out for ele¬ctron energies of 25.7eV , 35.7eV and 45.7eV , and electron scattering angles of 15°-40° extended to 8e = 45° at 45.7eV and 8e= 55° at E=35.7eV .
The Stokes parameters ,1^ and 9^ were measured and the sign change of the angular momentum transfered <Lj_> to the atoms was investigated using the circular polarisation results(P ). A sign change was found for the energies of 35.7 and 45.7 eV; the scattering angle at which the sign change occurs was fo¬und to decrease with increasing energy.
The total polarisation vector and the coherence parameters of the coincident photon radiation were evaluated in terms of the Stokes parameters to determine the coherent nature of the excitation process.
2 2
The excitation parameters \ = |a0|2 /2| + |a0|2 | = σo/σ( the- ratio of the partial differential cross-section excit¬ing the M^=0 substates to the total differential cross-sect¬ion ) and the magnitude of the phase difference |X| betwe¬en the excitation amplitude a for M^=l and M^= 0 states were obtained•
Finally from the analysis of these measurements the alignment angle (Y ) and the total linear polarisation P. of the charge cloud were obtained.
No other experimental or theoretical work has been published yet for the sake of comparison with our data.