Maximizing accuracy in half-life measurements, by minimizing error, with application to Bi-212 and Po-218

Thesis/Dissertation · Mon Jan 01 04:00:00 EST 1990

OSTI ID:5525481

Poupaki, I

Radon and short-lived progeny existing in all three primordial series, namely uranium, thorium and actinium, are of most significance for human exposure, since their inhalation is implicated in bronchogenic carcinoma. Because the dosimetric calculations utilize half-life, it is important to known this parameter with the maximum possible accuracy. The half-lives of Po-218 and Bi-212, radon-222 and radon-220 progeny, were measured as 3.078 {plus minus} 0.01 min and 59.81 {plus minus} 0.23 min respectively. Experimental data collected by {alpha}-counting included background from both the counter and the intrinsic radioactivity. A comparison of all mathematical methods presently employed in the analysis of experimental radioactivity decay is presented. Artificial data corresponding to three different nuclides, different total experimental duration, and different counting time intervals were generated. Testing these data showed that the WLSQ with the correct weighting factor gives the higher accuracy and precision. Without spectrometry, it is impossible to measure the quantity or half-life of Po-218 unless correction is made for the Po-214 daughter. For the measurement of Po-218, samples containing the short-lived radon-222 daughters were collected electrostatically. A method used to estimate the initial radon daughters concentration in air based on regression analysis is proposed. The comparison of this with the well known Thomas method using artificial data showed that the regression analysis method leads to more accurate results.

• Research Organization: New York Univ., NY (United States)
• OSTI ID: 5525481
• Country of Publication: United States
• Language: English

Related Subjects

663210* -- Ground-State Radioactivity-- (1992-)
663590 -- Nuclear Mass Ranges-- A=220 & Above-- (1992-)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACCURACY
ALPHA DECAY
ALPHA DECAY RADIOISOTOPES
ALPHA PARTICLES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BISMUTH 212
BISMUTH ISOTOPES
CHARGED PARTICLES
COMPARATIVE EVALUATIONS
DATA
DAUGHTER PRODUCTS
DAYS LIVING RADIOISOTOPES
DECAY
DOSIMETRY
ERRORS
EVALUATION
EVEN-EVEN NUCLEI
HALF-LIFE
HEAVY NUCLEI
HOURS LIVING RADIOISOTOPES
INFORMATION
ISOTOPES
LEAST SQUARE FIT
MAXIMUM-LIKELIHOOD FIT
MEASURING METHODS
MINUTES LIVING RADIOISOTOPES
NUCLEAR DECAY
NUCLEI
NUMERICAL SOLUTION
ODD-ODD NUCLEI
POLONIUM 218
POLONIUM ISOTOPES
RADIOISOTOPES
RADON 220
RADON 222
RADON ISOTOPES
SECONDS LIVING RADIOISOTOPES
YEARS LIVING RADIOISOTOPES