An intercomparison of the roentgen standards of great britain and U. S. A.

Physical aspects of irradiation: recommendations of the International Commission on Radiological Units and Measurements (ICRU) report 10B 1962

“…The estimated maximum uncertainty of about 0.5 percent is somewhat larger than that assigned to direct comparisons, though it is con¬ sidered that it should be possible to improve such transfer instruments so that indirect comparisons are almost as accurate as direct ones. Taking into account the greater uncertainty in the indirect comparisons by the circulation of these transfer instruments, the results of table IIA4 are con¬ sistent, where comparable, with those of earlier comparisons (Aston and Attix, 1956;Allisy et al, 1957) Free-air, cylindrical_ Thoraeus (1932Thoraeus ( ,1954. Thoraeus (1932Thoraeus ( , 1954 60 to 250_ _ ...do_ Wyckoff et al, (1954); Aston and Attix (1956).…”

“…Taking into account the greater uncertainty in the indirect comparisons by the circulation of these transfer instruments, the results of table IIA4 are con¬ sistent, where comparable, with those of earlier comparisons (Aston and Attix, 1956;Allisy et al, 1957) Free-air, cylindrical_ Thoraeus (1932Thoraeus ( ,1954. Thoraeus (1932Thoraeus ( , 1954 60 to 250_ _ ...do_ Wyckoff et al, (1954); Aston and Attix (1956). Ritz (1960).…”

Cavity ionization as a function of wall material

“…The 12-cm plate separation of this chamber [10] was inadcquate for the h eavily filtered X-rays used, and it was, therefore, calibrated against th e NBS 250-kv standard free-ail' ch amber [11] .…”

Intercomparison of French and U. S. Roentgen Ray Standards

“…The magnitude of these corrections is shown in Table I. Similar factors have already been published for the NBS chamber (1,5). The same air attenuation coefficient was used for the E. N. S. and NBS primary standards.…”