Electron-photon coincidence study of the collisional excitation of the 4 P-1(1) Ca state

Experimental values of the electron-impact coherence parameters (EICP) are reported for electron-impact excitation of the 4(1)P(1) state of Ca. The re sults have been obtained using electron-photon coincidence techniques for i ncident electron energies of 45 and 60 eV and scattering angles of 15 degre es. 20 degrees, 25 degrees, 30 degrees, 35 degrees and 40 degrees. EICP val ues determined at 45 eV are compared with similar data obtained by other gr oups with coincidence and optical pumping methods. Our data do not show a d isagreement with the theoretical calculations based an a relativistic disto rted-wave approximation (RDWA) that was reported for earlier experimental c oincidence results.