Angular distribution measurement of various L₃X-ray transitions

Abstract

The presence of the magnetic quadrupole term in addition to the electric dipole one in the multipole expansion of the radiation field is reflected in the angular distribution of the x-ray transition. To extend the previous works we studied the angular distribution of different L, x-ray liner of Ba, Sm and Er experimentally for proton impact at 0.23.0.28 and 0.35 MeV bombarding energies respectively, using a Si(Li) detector. The anisotropy parameter ratios of the LI and L a transitions were found to be 5.2i2.8, 5.5e0.7 and 6.93,l.S. Angular distributions of Tb L-shell x-rays were also measured by a high resolution crystal spectrometer for 0.556 MeVamu-' nitrogen ions, P value of 3.5e2.5 was obtained far the anisotropy parameter ratio. There ratios deviate significantly from the theoretical ones. The obtained ratios were in good accord with the same quantities derived from the earlier Ka,~Langularcorrelatian parameters. The effect ofthe magnetic quadrupole mining on the determination of the alignment parameter i s demonstrated for the case of the L, subshell of gold.

Deviation from the single-particle model in the angular distribution of thoriumL3x rays in proton-impact ionization

“…Similar to earlier studies [9,11,37] the present analysis shows that the anisotropy of various E1-allowed transitions deviates from the theoretical calculations carried out using the independent-particle model. The ratios of the anisotropy parameters are expected to be independent of the ionization process; however, they showed a dependence on the proton energy.…”

“…Since these ratios characterize the decaying atoms only, at first sight it might be thought that these ratios should be independent of the ionizing proton energies. This idea governed our earlier studies [6,9], where we carried out measurements at only one projectile energy, chosen to provide the maximum alignment value (A2= -0.5). This value is accidentally the same as the Az value of the L3 subshell in K-L angular correlations.…”

“…However, it should be emphasized that, to describe the angular distribution of inner shell x-ray transitions, the so-called single-particle or independent-particle models are used [7,8]. Later we extended the study to include a wide range of target atoms and collected all the available experimental data for the anisotropy parameter ratios of the Ll and L a transitions [9]. Previously only the anisotropies of these two transitions have been reported, and almost all the experimental data were in disagreement with the theoretically expected values.…”

Kinematic coefficient ratios, anisotropy parameters, and polarization degrees of L3 X-ray transitions of Bi, Pb, Ta, Lu, and Yb

“…Up to now, many experimental studies related with the angular distribution of the L 3 (J = 3/2) magnetic subshell X-ray transitions using different stimulating sources, such as synchrotron radiation [6][7][8], X-ray tube [9], radioisotope sources [10][11][12][13][14][15][16][17][18], and with charged particles [19][20][21][22][23][24] have been done.…”

“…The expected observed radiation in almost all of these experimental studies [20][21][22][23] has been generally assumed to consist of pure electric dipole (E1) transitions because the accepted very small effect of the magnetic quadrupole mixing higher-order multipole terms (forbidden transitions, such as M1, E2, M2, …) has been overlooked. This approximation is supported by theoretical results [25] obtained using relativistic singleparticle Hartree-Slater wave functions for the X-ray transition matrix element of different multipoles.…”