Cerium-123

Properties and data of the isotope ¹²³Ce.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Cerium-123 is a radioisotope of the chemical element cerium, which has 65 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 123. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ¹²³Ce is exclusively for academic purposes.

Cerium-123 was first experimentally detected in 1984. The isotope was produced in a fusion-evaporation reaction in which a molybdenum-92 target was bombarded with a 196 MeV Argon-36 beam: ⁹²Mo(³⁶Ar,αn)¹²³Ce. The reaction products were separated using an online isotope separator, and identification was achieved via coincidence measurements of β-delayed protons with characteristic X-ray emission.

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

General data

Name of the isotope:Cerium-123; Ce-123Symbol:¹²³Ce or 12358CeMass number A:123 (= number of nucleons)Atomic number Z:58 (= number of protons)Neutrons N:65Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.1206896551724 (= neutron-proton ratio)Neutron excess (N-Z):7Isotopic mass:122.93528(32) u (atomic weight of Cerium-123)Nuclide mass:122.9034646 u (calculated nuclear mass without electrons)Mass excess:-60.28629 MeVMass defect:1.081791396 u (per nucleus)Nuclear binding energy:1007.68219463 MeV (per nucleus)
8.19253817 MeV (average binding energy per nucleon)Separation energy:S_N = 10.484(499) MeV (first neutron)
S_P = 3.032(422) MeV (first proton)Half-life:3.8(2) sDecay constant λ:0.18240715277893 s^-1Specific activity α:9.003947277825 × 10⁺²⁰ Bq g^-1
24334992642.772 Ci g^-1Spin and parity:
(nuclear angular momentum)(5/2+)Year of discovery:1984

Radioactive Decay

Half-life T_½ = 3.8(2) s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC, β⁺	¹²³La	ca. 100 %	8.365(357) MeV
β⁺, p	¹²²Ba	> 0 %

Parent Nuclides

Direct parent isotope is: ¹²³Pr.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 65) and isobaric (same nucleon number A = 123) with Cerium-123. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 65	Isobar A = 123
36	¹⁰¹Kr
37	¹⁰²Rb
38	¹⁰³Sr
39	¹⁰⁴Y
40	¹⁰⁵Zr
41	¹⁰⁶Nb
42	¹⁰⁷Mo
43	¹⁰⁸Tc
44	¹⁰⁹Ru	¹²³Ru
45	¹¹⁰Rh	¹²³Rh
46	¹¹¹Pd	¹²³Pd
47	¹¹²Ag	¹²³Ag
48	¹¹³Cd	¹²³Cd
49	¹¹⁴In	¹²³In
50	¹¹⁵Sn	¹²³Sn
51	¹¹⁶Sb	¹²³Sb
52	¹¹⁷Te	¹²³Te
53	¹¹⁸I	¹²³I
54	¹¹⁹Xe	¹²³Xe
55	¹²⁰Cs	¹²³Cs
56	¹²¹Ba	¹²³Ba
57	¹²²La	¹²³La
58	¹²³Ce	¹²³Ce
59	¹²⁴Pr	¹²³Pr
60	¹²⁵Nd
61	¹²⁶Pm

External data and identifiers

Adopted Levels, Gammas:NuDat 123Ce

Literature and References

[1] - J. M. Nitschke, P. A. Wilmarth, P. K. Lemmertz, W.-D. Zeitz, J. A. Honkanen:
Beta-delayed proton emission observed in new lanthanide isotopes.
In: Zeitschrift für Physik, A, 316, 249-250, (1984), DOI 10.1007/BF01412274.