B. S. Sood

Measurement of L X-ray production cross sections in elements 57?Z?92 at 22.6 keV

L x-ray fluorescence cross sections have been measured for elements of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Ta, W, Au, Hg, TI, Pb, Bi, Th and U at a photon energy of 22.6 keV, using K conversion x-rays of Ag. The present results are discussed in the light of the other available experimental and theoretical results.

Experimental investigation of alignment of the L3 subshell vacancy state produced after photoionisation in lead by 59.57 keV photons

Experimental investigation of the alignment of the L3 subshell vacancy state produced after photoionisation in lead by 59.57 keV photons has been reported. The results confirm the prediction of the calculations of Flugge et al (1972) that the atomic inner-shell vacancies produced after photoionisation are aligned and the X-ray emission from the filling of vacancies in states with J>or=3/2 is anisotropic, but contradict the predictions of Cooper et al. (1969) that after photoionisation of the inner shell, the vacancy state has an equal population of magnetic substates and the subsequent X-ray emission is isotropic.

Experimental investigation of angular dependence of photon induced L-shell X-ray emission intensity

The angular dependence of emission intensity of L shell X-rays induced by 59.57 keV photons in Pb and U is investigated by measuring the normalized intensities of the resolved L X-ray peaks at different angles varying from 40° to 120°. It is observed that while Ll and Lα X-ray peaks (originating fromJ = 3/2 state) show some anisotropic angular distribution, the emission of Lβ and Lγ X-ray peaks is isotropic. The present results contradict the calculations of Co-oper and Zare (1969) that after photoionization of inner shell, the vacancy state has equal population of magnetic substates and the subsequent X-ray emission is isotropic but confirm the predictions of Fluggeet al (1972) that the atomic inner shell vacancies produced after photoionization are aligned and the x-ray emission from the filling of vacancies in state withJ ⩾ 3/2 is anisotropic.

Measurement of relative intensities of L-shell X-rays in some high-Z elements

The L-shell X-ray relative intensities I(Lalpha )/I(Ll), I(Lalpha )/I(Lbeta ) and I(Lalpha )/I(Lgamma ) for U, Th, Pb and the ratios I(Lalpha +l)/I(Lbeta ) and I(Lalpha +l)/I(Lgamma ) for W have been measured. The L-shell electrons are excited by 59.57 keV gamma rays from 241Am and the fluorescent L-shell X-ray intensities are measured with a Si(Li) detector. The experimental results are found to agree well with theory.

Measurement of K-shell fluorescence yields in elements 28⩽Z⩽53

Abstract The K-shell fluorescence yields in Ni, Cu, As, Zn, Se, Br, Zr, Nb, Mo, Ag, In, Sn, and I have been measured using photoionization for creating vacancies. The present results are found to agree well with the theoretical calculations and other available experimental data that have been obtained by using modes of excitation other than photoionization. To the best of our knowledge the values in the elements Ni, Zn, Se, Br, Zr, Nb, Mo, In, Sn and I have been measured for the first time.

L-shell photoelectric cross section measurements

L-shell photoelectric cross sections in Ta, W, Au, Pb, Th and U at 59.5 keV have been determined using three different versions of Soods method of measuring the absolute yield of fluorescent X-rays when a target is irradiated with a known flux of photons. The results obtained by all the methods agree with one another showing that no hidden systematic errors are involved in the measurements. The present results are found to compare well with the theoretical calculations of Scofield (1973).

Measurement of average M-shell fluorescence yields in some high Z elements

Abstract The average M-shell fluorescence yields ω M in Au, Pb, Th and U have been measured using the photoionization of the M shell by 5.9 keV X-rays from a 55Fe radioactive source and analyzing the M X-rays by a Si(Li) low-energy photon spectrometer. A comparison of the results is made with the existing experimental data and the values estimated from the subshell fluorescence yields calculated by McGuire, wherever possible. The measurement for Th is reported for the first time.

M-shell x-ray production cross sections in Au, Pb, Th and U by 6-12 keV photons

The cross sections for the production of M-shell X-rays in thick targets of Au, Pb, Th and U by photons of energy 6-12 keV have been measured. The measured cross sections are compared with those calculated from the theoretical values of the M-subshell photoionisation cross sections, fluorescence yields and Coster-Kronig yields. A fairly good agreement is found between the present results and the calculations within the uncertainties of the determination.

Measurement of Ll+α, Lβ and Lγ X-ray production cross sections in some rare-earth elements by 10, 18, 26 and 33 keV photons

The cross sections for the production of Ll+ alpha , Lbeta and Lgamma X-rays in Nd, Sm, Eu Gd, Dy, Er, Yb and Lu by photons with energies of 10.005, 17.781, 25.77 and 32.89 keV have been determined. Fairly good agreement is found between the experimental and calculated values. Contrary to the findings of Garg et al (1986) that the experimental values are 5-20% higher than the calculated values, our results do not show any systematic regular trends which would indicate any departure from theory. Plausible reasons for the discrepancy reported by Garg et al are discussed.

Determination ofL-shell X-ray production cross-sections in holmium by 10–40 keV photons

In an effort to resolve the existing discrepancy between experiment and theory, the cross-sections for the production ofLl,Lα,Lβ andLγ groups ofL-shell X-rays of Ho by photons of nine energies in the range 10–40 keV have been measured using an improved version of annular source double reflection geometrical set-up. Contrary to the earlier findings of Garget al that the measured values of the cross-sections are consistently higher than those calculated theoretically, the present results do not confirm this. The plausible deficiencies in the experiments of Garget al are pointed out and possible remedies to overcome them are suggested. It is concluded that the higher values obtained by Garget al are probably due to systematic errors in their method of measurement.