Cesium-barium generator
A cesium-barium generator is a radionuclide generator that is used in physics classes to demonstrate the half-life of radioactive decay .
Cesium -137 is radioactive and decays with a half-life of around 30 years with the release of beta radiation to form metastable barium -137m. This is washed out of the cesium during the experiment and then disintegrates with a half-life of around 2.5 minutes with the release of gamma radiation to form stable barium-137. Since the barium separated from the cesium is no longer continuously reproduced in the eluate, this shorter half-life can be measured. Before washing out, only constant gamma radiation can be detected.
Due to the short half-life, the exponential decrease in radiation can be easily understood in the classroom without having to purchase a short-term radionuclide with a short half-life. The stable barium can be safely disposed of after a short time.
The increase in gamma radiation in the parent substance after washing out through the formation of new barium can also be measured.
Regulations
A generator for teaching purposes usually has an activity of 370 kBq .
In Germany, according to the Radiation Protection Ordinance, handling is not subject to approval, but notifiable if a valid type approval is available. Otherwise a handling permit is required.
In Switzerland there is no license or notification requirement, but the radiation protection regulations must be observed.
literature
- RL Hayes, WR Butler: Growth and decay of radionuclides: A demonstration. In: Journal of Chemical Education . 37, 11, 1960, pp. 590-592, doi : 10.1021 / ed037p590 .
- JJ Pinajian: A cesium-137-barium-137m isotope generator. In: Journal of Chemical Education. 44, 4, 1967, pp. 212-213, doi : 10.1021 / ed044p212 .
- Patent US3566124 : Miniaturized radioisotope generator. Filed April 12, 1968 , published February 23, 1971 , applicant: Union Carbide , inventor: Wayne Joseph Gemmill.