The radioactive isotope Cf-252 is a powerful, spontaneous emitter of neutrons. It is used for a range of applications in the nuclear, medical, military, and coal and oil industries. Because it readily emits neutrons, only a particle of Cf-252 is needed for most uses; however, it is important to verify the activity level of each piece, by counting the number of neutrons it emits.
Measuring Neutron Source Activity
The process begins with a piece of Cf-252 that is encapsulated in a welded, stainless steel capsule. In this form, the isotope is known as a neutron source (learn more about Frontier’s neutron sources here: https://frontier-cf252.com/products/neutron-sources/).
A special device called a DePangher Precision Long Counter is used to count emissions from both the source being calibrated (i.e., the source being purchased by a customer) and a comparably sized AmBe source (which establishes a baseline). The standard AmBe source is calibrated by NIST, resulting in the Cf-252 source being certified NIST-traceable.
First the neutron emission rate of the AmBe source is counted, and then the rate of the source being calibrated is counted. Both are rotated in a horizontal plane around their axial centers during counting, and no geometric, electronic, environmental, or other changes/adjustments are made between counts to ensure precision in the conditions and an accurate reading. Corrections are applied for decay, neutron spectrum, and related scattering differences between the standard source and the source being calibrated and counter dead time. Microgram equivalence has been calculated from the Cf-252 neutron emission rate using the conversion factor 2.311 x 10 6 n/s per microgram of Cf-252.
Because the process involves the release of neutron radiation, it is conducted in an isolated area that is well shielded and with no personnel in the vicinity. This helps protect their health and safety during the calibration process.
Matching The Source Application Requirements
Source calibration is the only way to verify that it emits a suitable amount of neutron activity for a given application. Depending on the results and the source activity, the amount of Cf-252 can be adjusted prior to encapsulation to reach the desired level of neutron emission.
Common applications for neutron sources include, but are not limited to:
- Nuclear reactor startup
- Material analysis for coal and oil excavation
- Portable isotopic neutron spectroscopy for explosive detection
- Research reactors
- Equipment calibrations
Choose Frontier for Neutron Emitting Sources
Frontier Technology Corporation is a global supplier of Cf-252 neutron sources, Type-A shipping containers, and WEP-filled neutron shielding walls. Located in southwest Ohio, our team brings decades of experience to each customer and project. Contact us to learn more about our products and services!