Measurement of Total Attenuation Cross Sections in Aluminum and Gold for 14.4-keV Gamma Rays

Abstract

Total attenuation coefficients of aluminum and gold for 14.4-keV gamma rays have been measured using a resonant (i.e., Mossbauer) detector to reduce forward scattering and background corrections. The results are 390.7=b0.7 and 59 290±70 barns per atom for aluminum and gold, respectively. These values imply photoelectric cross sections of 371.0=1=0.7 and 58 220d=70 barns/atom, respectively. The results are in agreement with other, less precise, measurements in this energy region. Present theoretical estimates of these cross sections are high by 5% for aluminum and 35% for gold.

Measurement of the x-ray mass-attenuation coefficients of gold, derived quantities between 14 keV and 21 keV and determination of the bond lengths of gold

“…The most interesting comparison is with the most accurate measurements. Alonso and Grodzins [18] claimed to have measured the mass-attenuation coefficient of gold at 14.4 keV to an accuracy of 0.1%-a claim five times more accurate than any measurement before ours. However, the energy of the x-ray beam was only specified to one decimal place (in keV).…”

“…The work of Allen is particularly discrepant from the other data, and is more than 10% higher than the other measurements, although this is a very early measurement. The most accurate experiments were performed by Hughes et al [17] and Alonso et al [18]. In the region of the L I edge, these two experiments appear discrepant and there are reasons to doubt the uncertainty estimates of Alonso et al (see section 8 of this paper).…”

“…Table 1 summarizes the details of the eight publications that included estimates of their uncertainties (25 measurements in total). These earlier measurements had uncertainties ranging from 1% to 3%, except for a single point measurement at 14.4 keV by Alonso and Grodzins [18] which claimed an accuracy of 0.1% and three measurements by Hughes et al [17] who claimed an accuracy of 0.5%. In figure 12, our results are compared with these earlier measurements.…”

“…Allen [20] X-ray tube 12.4-17.5 4 1 Laubert [21] X-ray tube 14.1-20.2 8 3 Alonso and Grodzins [18] Nuclear Zeeman effect 14.4 1 0.1 Bearden [22] X-ray tube 15-20 2 1 Hughes et al [17] Electron microprobe 14-22 3 0.5 Parthasaradhi and Hansen [23] Radioactive isotope 14-21 2 2 Hanser and Sellers [24] Radioactive isotope 6-15 1 1.9 Rao and Shahnawaz [25] Radioactive isotope 14.4 1 2 Del Grande [26] X-ray tube 15-20 3 3…”