Performance of vintage direct reading pocket ionization chambers.
The linearity, accuracy, and precision of each of two groups of vintage 51.6 microC-kg-1 maximum scale passive direct reading pocket ionization chambers, each from a different manufacturer and all aged at least 50 years since manufacture, were tested. The pocket ionization chambers were suspended on a phantom and exposed using a 137Cs source. Variations from trial to trial were smaller than variations from chamber to chamber. The average percent standard deviations ranged from 5.7% to 14% across all exposures. The accuracy of the dosimeter readings increased as the exposure level increased. Percent error from known exposure values decreased as exposure increased. An independent samples t test indicated there was a statistically significant difference between the two groups only at a delivered exposure of 6.45 microC-kg-1. Testing was performed in a 222Rn drum to determine the effect of Rn on the pocket ionization chambers. Exposure of five chambers to an average Rn level of 4.70 kBq m-3 and thirty chambers to 3.86 kBq m-3 over a 7-d period produced abnormally high readings at least three times background in eight of the 35 chambers tested.
Bergen
Robert J
RJ
Department of NERS, University of Michigan, 2355 Bonisteel Blvd., Ann Arbor, MI 48109-2104, USA. rjbergen@umich.edu
Harvey
John A
JA
Kearfott
Kimberlee J
KJ
D002138:Calibration; D002588:Cesium Radioisotopes / Q000032:analysis; D004867:Equipment Design; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011834:Radiation Monitoring / Q000295:instrumentation* / Q000706:statistics & numerical data; D011874:Radiometry / Q000295:instrumentation* / Q000706:statistics & numerical data; D011886:Radon / Q000032:analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013997:Time Factors
D002588:Cesium Radioisotopes; D011886:Radon