Cerium-144 is a radioisotope of the chemical element cerium, which has 86 neutrons in its atomic nucleus in addition to the element-specific 58 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 144.

The discovery of the isotope Cerium-144 was made in the context of fission product research conducted as part of the Manhattan Project at Argonne National Laboratory. In these studies, W. H. Burgus et al. investigated the decay products of uranium-235 that had been exposed to thermal neutrons. Following chemical separation of the fission products, a long-lived cerium activity with a half-life of approximately 275 days was identified. This measurement corresponds remarkably well to the currently accepted value of 284.9 days [original publication: Burgus, Weinberg, Seiler, Rubinson (Argonne/Plutonium Project): Characteristics of the 275d 144Ce, NNES (National Nuclear Energy Series), Div. IV, Vol. 9, Radiochemical Studies: The Fission Products].

Earlier observations of such an activity date back to Hahn and Strassmann, who, in the late 1930s, had already suspected the existence of two cerium isotopes with half-lives of roughly 20 and 200 days, although they were unable to make a definitive mass assignment. The decisive step was taken by Burgus and co-workers, who interpreted the long half-life and the low β-energy as an indicator of a mass number in the 144 region. This assignment was subsequently confirmed by mass spectrometry performed by Lewis and Hayden [1]. This evidence was based on internal reports of the plutonium Project, which were not fully published at the time.

Because the mass assignment was explicitly made in this work and supported by physical measurements, Burgus et al. are recognized as the discoverers of ¹⁴⁴Ce. This case illustrates a characteristic feature of early postwar nuclear research, in which key results initially existed only in internal project reports before being systematically compiled and published later on.

¹⁴⁴Ce is a strong source of electron antineutrinos. The antineutrino flux arises from the successive β-decay of cerium-144 and praseodymium-144, making the isotope particularly interesting for experimental particle physics.

See also: List of individual Cerium isotopes (and general data sources).

General data

Radioactive Decay

Cerium-144, like its daughter nuclide praseodymium-144, undergoes β-decay, in which a neutron is converted into a proton with the simultaneous release of an electron and an electron antineutrino: n → p + e^- + ν^-e. The significant contribution to the antineutrino flux intensity comes from the short-lived Pr-144 (half-life 17 minutes).

Half-life T_½ = 284.886(25) d respectively 2.46141504 × 10⁷ seconds s.

Figure above: Antineutrino energy spectrum of ¹⁴⁴Ce. The normalized ν̄_e spectrum (area = 1) is derived from measured β⁻ data using E_ν = Q_Ce − T_e with Q_Ce = 318.6 keV. The black profile shows the data-based reference curve. For a compact description, a simple three-branch model with end-point energies of 318.6 keV, 220 keV, and 180 keV is overlaid; it includes the Coulomb interaction via the Fermi function and a generic first-forbidden non-unique shape treatment. The model provides a practical approximation to the experimental distribution across the full energy range and represents the electron-antineutrino energy distribution per decay of ¹⁴⁴Ce.

Parent Nuclides

Direct parent isotope is: ¹⁴⁴La.

Formation

Cerium-144 is extracted almost exclusively from the fission products of spent fuel elements. It is produced with high yield during the thermal fission of uranium-235 and plutonium and, after an appropriate decay time, is present in significant activity and concentration. It is obtained by radiochemical processing of the fuel, in which the rare earth fraction is first dissolved and then separated using liquid-liquid extraction, ion exchange, or extraction chromatography. These steps are technically demanding because cerium is chemically almost indistinguishable from other lanthanides, and companion isotopes require a high degree of radiological shielding.

Alternatively, Ce-144 can also be produced by successive neutron capture reactions from stable cerium isotopes or by spallation in accelerators. However, such processes are less efficient and are primarily used for specialized applications. In all cases, the radiochemical separation processes are complex, as high purities are required and the handling of highly active materials is subject to strict regulatory requirements. This essentially limits production to specialized nuclear facilities.

Use

There are a few practical applications for radioactive cerium-144, primarily in experimental neutrino physics and radiation metrology/calibration; industrial applications are being investigated theoretically and experimentally, but are comparatively rare due to logistical, radiological, and regulatory reasons.

Isotones and Isobars

Data changes (history)

• Half-lives: The relevant data sources essentially cite three different values ​​for the half-life of Cer-144. An older but more common value is T_1/2 = 284.91(5) days (JAEA/IAEA). The 2014 figure is 284.89(6) days (DDEP/LNHB). The AME2020 value was adopted here: 284.886(25) days.

External data and identifiers

Literature and References

[1] - Richard J. Hayden:
Mass Spectrographic Mass Assignment of Radioactive Isotopes.
In: Physical Review, 74, 650, (1948), DOI 10.1103/PhysRev.74.650.

[2] - A. S. Gerasimov et al.:
Production of High Specific Activity ¹⁴⁴Ce for Artificial Sources of Antineutrinos.
In: Atomic Energy, 116, 54 - 59, (2014), DOI 10.1007/s10512-014-9816-1.

[3] - Aurélien Beaumais et al.:
Determination of the ¹⁴⁴Ce/²³⁸U atomic ratio in spent nuclear fuel using double spike isotope dilution mass spectrometry.
In: Journal of Analytical Atomic Spectrometry, 37, 1288 - 1297, (2022), DOI 10.1039/D2JA00052K.

[4] - A.V. Derbin, I.S. Drachnev, D.V. Ivanov et al.:
The precision measurement of the electron anti-neutrino spectrum in beta-decay of ¹⁴⁴Ce-¹⁴⁴Pr nuclei.
In: arXiv, (2025), DOI 10.48550/arXiv.2506.03716.

Last update: 2025-10-25

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