Californium-252 (Cf-252)

Cf-252 sealed sources are a cost-effective neutron source used in a variety of medical, industrial, and security applications.

Our Californium-252 sealed source designs provide a cost-effective alternative to OEMs, meeting or exceeding regulatory requirements for radiation source encapsulations.



Half Life: 2.65 Years

Primary Emission: Neutron

Primary Energy: 2 MeV

RWL: 15 Years

Capsule Materials: MP35N; stainless steel


Californium-252 History

Californium was first synthesized at the University of California, Berkeley by researchers Stanley G. Thompson, Kenneth Street, Jr., Albert Ghiorso and Glenn T. Seaborg in 1950. It was the sixth transuranium element to be discovered. The team announced their discovery on March 17, 1950. It is suggested that element 98 be given the name californium (symbol Cf) after the university and state where the research was completed.


Californium-252 Applications

Oil Well Logging (OWL) – Cf-252 is used in oil exploration applications such as wireline logging and logging while drilling.

Californium-252 sources are designed to withstand forces encountered during oil well logging, wireline logging, oil wellsite analysis, and oil well sampling without compromising encapsulation integrity.

Thickness Gauging – Californium-252 is used to measure light alloys, glass, plastics, and rubber for which beta sources are not suitable.

Reactor Startup – Californium reactor start-up sources are enclosed in welded, corrosion-resistant encapsulations, designed to yield high levels of neutron output without compromising the integrity of the source.

Fuel Rod Scanning – Californium measures the content of fissile material in mixed oxide fuel rods.

Materials Analysis – Californium-252 excites radiation in non-destructive testing elemental analysis applications.

Medical – Cf-252 is widely used for a variety of medical research and healthcare applications, including cancer treatment.



Measured by National labs and statistically verified by QSA. Standard certificates available upon request.. All californium sources can be made with closely matched neutron emissions, with tolerances within ±5%.


Custom Design Services

QSA has a large standard product list available to fit your application. Custom Californium source designs are possible for large orders. Contact QSA for more information.


Quality Control

QSA Global uses a multi-part quality assurance system to ensure Californium-252 radiation sources meet the highest integrity levels in the industry, including all statutory and international regulatory requirements.

Weld validation is accomplished by taking pre-production weld sections prior to all production batches.

Wipe Test I – Californium-252 sources are wiped with a swab or tissue, moistened with ethanol or water, then measured for removed activity.

Immersion Test II – Californium-252 sources are immersed in a suitable liquid at 50°C for at least 4 hours, then measured for removed activity.

Bubble Test III – Californium-252 sources are immersed in water or a suitable liquid, and the pressure in the vessel is reduced to 13kPa (100mm Hg). No bubbles must be observed.

Helium Leak Test – Detects Cf-252 encapsulation leak rates of up to 10-10 mbar l / s.

Contact QSA for additional information on Californium-252 sealed source encapsulations.