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Updated: Dec 17, 2025
10:24
Neutron Radiography and Computed Tomography of Biological Systems at the Oak Ridge National Laboratory's High Flux Isotope Reactor
Published on: May 7, 2021
2.7K
Characterization of 244Cm neutron sources.
Radoslav Radev1, Thomas D McLean2
1Lawrence Livermore National Laboratory, PO Box 808, L-186, Livermore, CA, 94550, USA.
Summary
Californium-252 (Cf-252) neutron sources are being replaced by Curium-244 (Cm-244) due to availability and cost. Cm-244 offers a longer half-life and a similar neutron spectrum, making it an ideal alternative for neutron instrumentation testing.
Area of Science:
- Nuclear Physics
- Neutron Detection and Measurement
Background:
- Current standards-based performance testing of neutron instrumentation relies on Californium-252 (Cf-252) sources.
- Challenges with Cf-252 include its short half-life, availability concerns, and increasing costs.
- A need exists for a suitable replacement neutron source for instrumentation calibration and testing.
Purpose of the Study:
- To evaluate Curium-244 (Cm-244) as a potential replacement for Cf-252 neutron sources.
- To characterize the neutron emission spectrum and emission rate of Cm-244 sources.
- To compare the suitability of Cm-244 with Cf-252 for performance testing applications.
Main Methods:
- Acquisition and measurement of neutron emission spectra from two commercially available Cm-244 sources using spectrometers.
- Comparison of measured Cm-244 spectra with MCNP6®-calculated spectra using Watt fission parameters.
- Determination of the Cm-244 source emission rate via direct count rate comparison with a calibrated Cf-252 source.
Main Results:
- The measured neutron emission spectra of the Cm-244 sources were in excellent agreement with MCNP6® simulations.
- The emission rate of the weaker Cm-244 source was consistent with its manufacturer's certificate.
- Cm-244 exhibits a longer half-life (18.1 years) compared to Cf-252 and a nearly identical neutron emission spectrum.
Conclusions:
- Curium-244 (Cm-244) is identified as an ideal replacement for Californium-252 (Cf-252) in neutron instrumentation testing.
- The availability of Cm-244 sources at reasonable costs further supports its adoption.
- The study validates Cm-244's suitability based on its physical properties and spectral characteristics.
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