Optical potential approach to electron and positron scattering from noble gases. I. Argon

Abstract

We apply an optical potential method to electron and positron scattering from noble gases and present numerical results for the scattering from argon atoms at intermediate energies (15-100 eV). We present results using a ten-state optical potential as well as our polarised-orbital polarisation potential plus the imaginary part of the optical potential. This latter approximation produces cross sections which are similar to those of our previous electron and positron polarised-orbital calculations, although in the case of positrons the predicted local minimum in the differential cross section for small angles is reduced. The full optical potential results produce the best overall agreement with experiment for both electrons and positrons.

Positron scattering from rare gases (He, Ne, Ar, Kr, Xe, and Rn): Total cross sections at intermediate and high energies

“…As was the case in positron-Ne scattering (see Fig. 2), the optical-potential calculations (20 -100 eV, dashed curve D) of Bartschat, McEachran, and Stauffer [45] are too low, again due to insufficient inclusion of inelastic channels (particularly the ionization process). The high-energy optical model calculations of Joachain et al.…”

“…[40]); dashed curve D, optical potential results of Ref. [45]. Experimental data: X, Kauppila [24] ( X ), [21] (0 ), and [12] (+).…”

“…[48]). The only intermediate-energy (1 -100 eV) calculations on the cr, for Ne and Ar systems are due to Bartschat, McEachran, and Stauffer [45,46], who employed an optical-potential method, quite similar to the present one except for the choice of optical potential; however, due to the neglect of ionization and Ps formation channels in the evaluation of optical potential, their o. , values are too low in comparison to the experimental data (see later). It is rather disappointing that very little 46 1279 K. L. BALUJA AND ASHOK JAIN 46 [2]; 4-19 [3]; 2-400 [4]; 4 Ep, - [5] 19-27 [7]; 16 -270 [9]; 50 -400 [10]; 2 -960 [12]; 2-18 [14] 0.3 -31 [ [20]; 0.35 -100 [21]; 1-6 [22]; 20-800 [24] none Theory 100 -3000 [37]; 100 -500 [38] 100 -700 [39]; 50 -1000 [41] 200-3000 [37]; 100-500 [38] 100-800 [42]; 1 -100 [46] 100-1000 [40]; 100 -800 [43] 3 -300 [44]; 1-100 [45] none none none attention has been paid theoretically to determine total cross section for positron-atom scattering at intermediate and high energies.…”

Recommended Positron Scattering Cross Sections for Atomic Systems

“…The earlier model used by Bartschat et. al [101,102] had studied it in the nonrelativistic formalism and did not allow for the continuum channels.…”

Critical minima in elastic electron scattering from argon

“…In addition, several calculations have been performed in order to make comparison with experimental data and at the same time to test theoretical methods (e.g. Kemper et al (1985), Walker (1971), McEachran and Stauffer (1983), Bartschat et al (1988), Mimnagh et al (1993), Nahar and Wadehra (1987), Fon et al (1983), Saha (1991), Sienkiewicz and Baylis (1987), Haberland et al (1986), Plenkiewicz et al (1988), Ihra and Friedrich (1992)).…”