USGS Science⌕ Search
Home/Archive/USGS

USGS · 70010475

Half-life of Th232 and the branching ratio of Bi212

F. E. Senftle·T. A. Farley·N. Lazar
View original source ↗Export metadata ↓

Abstract

The half-life of Th 232 has been calculated by determining an absolute gamma-disintegration rate for Tl 208 in equilibrium with Th 232 for three old thorium nitrate salts and one natural thorite sample. The branching ratio, α/ ( α + β ) , for Bi 212 , a necessary parameter in the calculation, was also measured. The half-life of Th 232 was found to be 1.42× 10 10 years within an estimated error of 5%, which is essentially in agreement with the presently accepted value. The branching ratio, α/ ( α + β ) , of Bi 212 was found to be 0.362±0.006, about 7.4% higher than the currently accepted value.

Explore related subjects

Physical ReviewArticle

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

F. E. Senftle, T. A. Farley, N. Lazar. 1956-12-15. Half-life of Th232 and the branching ratio of Bi212. https://doi.org/10.1103/physrev.104.1629

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS1968

Van vleck paramagnetism in orthorhombic TiO2 (Brookite)

The magnetic susceptibility of the orthorhombic form of titanium dioxide has been measured from 5 to 300°K. After deducting the temperature-dependent component, which is probably due to defects or impurities, and the free-ion diamagnetic component, the Van Vleck paramagnetism was estimated to be 33× 10 − 6 emu/mole. Comparison is made between this value and the Van Vleck paramagnetism of strontium titanate and the two tetragonal forms of titanium dioxide: rutile and anatase.

Physical Review↗
USGS1960

Magnetic susceptibility of tetragonal titanium dioxide

Careful measurements have been made of the magnetic susceptibility of the rutile and anatase crystalline forms of titanium dioxide. The magnetic susceptibility of a single crystal of high-purity rutile was found to be (0.067±0.0015)× 10 − 6 emu per gram, and was temperature-independent from 55° to 372°K. Difficulty was encountered in obtaining a good value of the magnetic susceptibility of anatase because of impurities. However, a value of 0.02× 10 − 6 emu per gram was obtained as a maximum value for anatase powder. A discussion is given for the different values obtained for anatase and rutile.

Physical Review↗
USGS1954

Thick target bremsstrahlung spectra for 1.00-, 1.25-, and 1.40-Mev electrons

The spectrum of radiation produced by 1.0-, 1.25-, and 1.40-Mev electrons incident on a thick tungsten target was measured at 0° and 90° with the incident beam by a method involving the magnetic analysis of Compton electrons. The effects of electron scattering and energy loss in the target preclude any simple interpretation of this data to yield a differential bremsstrahlung cross section. However, an estimate of the spectra to be expected at 0° and 90° was obtained by combining the Sauter expression for the bremsstrahlung cross section with the available information on electron scatter and energy loss in the target and backscatter from the target. The reliability of the estimate is limited because the Sauter formula was calculated by using the Born approximation, the electron scattering calculations are applicable to an infinite medium only, and the backscatter was estimated empirically from Bothe's experimental data which were obtained with lower energy electrons (370 kev). Furthermore electron energy straggling was neglected. Nevertheless, the predicted spectral shapes at 0° and 90° and the relative intensities at these two angles are in qualitative agreement with the measured values. The absolute magnitudes of the measured intensities at both angles are about a factor of two greater than the predicted values.

Physical Review↗