Uncertainties associated with the calibration and use of NBS pressurized 4. pi gamma. ionization chamber A
The radioactivity group at the US National Bureau of Standards (NBS) retains most of its calibrations for gamma-ray-emitting radionuclides on one or more of four pressurized 4..pi gamma.. ionization chambers. The oldest of these is chamber A. Chamber A is a steel-walled reentrant chamber with an 18.5-cm o.d., a length of 43 cm, and an approx.3.8-cm i.d. A plastic insulating sleeve and a 0.3-cm-thick brass liner reduce the useful inside diameter to approx.2.5 cm. The chamber contains purified argon at a pressure of 20 atm. During the 20 yr that it has been in use, calibrations for approx.70 radionuclides have been transferred to chamber A (as well as to some of the other chambers). Some of the calibrations are primarily for impurity radionuclides, but most are for radionuclides that are (or were) distributed as NBS standards. The extent, age, and accuracy of these calibrations were recently reviewed in order to determine the priorities for future recalibrations and new calibrations to be undertaken. The results of this review are presented and discussed. In addition, an attempt was made to enumerate all sources of uncertainty that arise in the process of making the ionization-chamber measurements themselves and to evaluate the relative importance of each. The relative importance of the various sources of uncertainty are presented for several typical measurements.
- Research Organization:
- National Bureau of Standards, Washington, DC
- OSTI ID:
- 6944375
- Report Number(s):
- CONF-861102-
- Journal Information:
- Trans. Am. Nucl. Soc.; (United States), Journal Name: Trans. Am. Nucl. Soc.; (United States) Vol. 53; ISSN TANSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ACCURACY
ACTIVITY LEVELS
CALIBRATION
ELECTROMAGNETIC RADIATION
GAMMA RADIATION
IMPURITIES
IONIZATION CHAMBERS
IONIZING RADIATIONS
MEASURING INSTRUMENTS
NATIONAL ORGANIZATIONS
RADIATION DETECTORS
RADIATIONS
STANDARDS
US DOC
US NBS
US ORGANIZATIONS