Anomalous density effect near the interface between two media

Abstract

A theoretical investigation is presented for the local energy loss of a relativistic charged particle and the K-shell excitation cross section aK when the particle crosses a sharp interface between two different media. The logarithmic increase of the local energy loss and o-K with the particle energy is shown to differ essentially from the case of a homogeneous medium. The calculations of e~ for aluminum and copper foils are in good agreement with the experimental data.

Density effect in relativistic K-shell ionization

“…For 5.1 GeV, a u could not be determined (see footnote (d) of Table 1), but the ratio au/tr s has been shown to be very close to that predicted by [3] (see [11]). In each case, the lower line is from [3] and the upper line from [4]. Also, the Z-dependence of the cross sections is confirmed to within the precision of the experiment.…”

“…(2) The absolute values of a, and a~ are given in Fig. 3, in comparison with theoretical calculations [3,4]. The contributions to the total uncertainties in the measured cross sections are listed in Table 1.…”

“…a o where/~ is the self-absorption coefficient for the target K X-rays in the target material and l is a constant (~ 4 for A1 and --~3 for Cu [4]). Then, the yield per projectile electron of detected X-rays emerging from the backside (B) of the target is…”

K-shell ionization and characteristic x-ray radiation by high-energy electrons in multifoil targets

“…( 6), such a photon spectrum, in accordance with Refs. [13,14], results in the conventional K-shell ionization cross section unaffected by the density effect. As shown in [13], at high electron energies the value of this cross section, predicted by the currently applied method (which is the same as in [13]), coincides with the experimental results (obtained in the measurements with very thin foils) with almost the same accuracy as the results of more rigorous theories.…”

“…A series of experimental [1][2][3][4][5][6][7][8][9][10] and theoretical [8,[11][12][13][14] works has been devoted to study of cross section of K-shell ionization by high-energy particles with the aim of investigating the influence of medium polarization upon it. Such an influence is known as the density effect [15,16], which leads to partial suppression of particle ionization loss at high energies.…”