Measurements of K shell photoelectric cross sections

K shell photoelectric cross sections for lead were determined with an ironfree double focusing beta-ray spectrometer. Comparison of intensities of internal and external conversion lines from the 1.332 MeV gamma-ray transition following the decay of 60Co gave τK = (3.24±0.13) b per atom. The ratio of the cross sections at 2.754 and 1.368 MeV gamma transitions following the decay of 24Na is 0.30±0.02, as found by comparison of the external conversion lines. The cross section at 2.754 MeV calculated from the above mentioned values is (0.93±0.07) b per atom. These results support Pratt's recent calculations for K shell photoelectric cross sections.