Double Vacancies in theKShell Associated withK-Electron Capture inA37

Abstract

The pulse-height spectrum produced by the decay of A 37 in a proportional counter was analyzed to determine the probability, per i^-electron capture, for the production of a double vacancy in the K shell. The double vacancy is produced by promotion of the second K electron to a bound state or to the continuum. In these experiments both processes could be observed; the measurements included events in which the kinetic energies of the promoted electrons were in the range zero to 4.0 kev. Seventy-three percent of the theoretically predicted total effect should occur in this energy interval. The data, appropriately corrected, give for the probability of double X-vacancy production per K capture, in the energy interval investigated, 3.9±0.7X10~4. The result is substantially in agreement with the value calculated from theory.f Research carried out under the auspices of the U. S. Atomic Energy Commission. 1

Double K-photoionization of heavy atoms

“…2 one of those scaling laws (Forrey et al, 1995). It shows excellent agreement with the asymptotic ratios measured in He by Spielberger et al (1995) and by the EC measurements in Ag (Ko et al, 1998), Cl ðZ ¼ 17Þ (Miskel and Perlman, 1954), Mn ðZ ¼ 25Þ (Briand et al, 1974), and Rb ðZ ¼ 37Þ (Schupp and Nagy, 1984). In contrast, those measurements in the peak region, besides being obviously systematically higher, also fall off significantly slower than the 1=Z 2 -dependence of SO.…”

Higher-order processes in X-ray photoionization of atoms

“…That scaling law shows excellent agreement with the asymptotic ratios measured in He by Spielberger et al (1995) and by the EC measurement in Ag (Ko et al, 1998). The other EC measurements in the figure include Cl ðZ ¼ 17Þ (Miskel and Perlman, 1954), Mn ðZ ¼ 25Þ (Forrey et al, 1995). Also shown (solid line) is our 1=Z 1:61 power-law fit.…”

Radioactivity ofSc44

“…From the fact that the intensity was independent of the source thickness and the spectrometer used, and after excluding a number of possible explanations, Bruner came to the conclusion that the electrons were emitted in the process of positron decay. Their number, however, greatly exceeds that predicted by the theories of atomic excitation during beta decay [5][6][7] which, on the other hand, have been found to be in essential agreement with experiments on the K and L ionization [8][9][10][11][12][13] and the emission of low-energy electrons 14 ' 15 in several cases of negatron emission and electron capture. For Sc 44 the formulas of Migdal 6 yield a total ionization probability of about 5% (which may be too large according to the Z-shell results of Levinger 7 ).…”