Cerium-126

Properties and data of the isotope ¹²⁶Ce.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Cerium-126 is a radioisotope of the chemical element cerium, which has 68 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 126. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ¹²⁶Ce is exclusively for academic purposes.

The first observation of the neutron-poor nuclide Cer-126 was described in 1978. The isotope was created by fusion-evaporation reactions in which a sulfur-36 beam with an energy of 190 MeV was fired at Ru targets (ruthenium-96 and ruthenium-98). The reaction residues were mass-separated and detected using X-rays and β-radiation: ^96,98Ru(³⁶S,xn)¹²⁶Ce (x = 6,8) [1].

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

General data

Name of the isotope:Cerium-126; Ce-126Symbol:¹²⁶Ce or 12658CeMass number A:126 (= number of nucleons)Atomic number Z:58 (= number of protons)Neutrons N:68Nucleon pairing (Z - N):even - evenNuclear ratio (N/Z ratio):1.1724137931034 (= neutron-proton ratio)Neutron excess (N-Z):10Isotopic mass:125.92397(3) u (atomic weight of Cerium-126)Nuclide mass:125.8921546 u (calculated nuclear mass without electrons)Mass excess:-70.82149 MeVMass defect:1.119096144 u (per nucleus)Nuclear binding energy:1042.43134356 MeV (per nucleus)
8.27326463 MeV (average binding energy per nucleon)Separation energy:S_N = 12.234(198) MeV (first neutron)
S_P = 4.350(38) MeV (first proton)Half-life:51.0(3) sDecay constant λ:0.01359112118745 s^-1Specific activity α:6.547811698823 × 10⁺¹⁹ Bq g^-1
1769678837.5199 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Year of discovery:1978

Radioactive Decay

Half-life T_½ = 51.0(3) s respectively 5.10 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC/β⁺	¹²⁶La	100 %	4.153(95) MeV

Parent Nuclides

Direct parent isotope is: ¹²⁶Pr.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 68) and isobaric (same nucleon number A = 126) with Cerium-126. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 68	Isobar A = 126
38	¹⁰⁶Sr
39	¹⁰⁷Y
40	¹⁰⁸Zr
41	¹⁰⁹Nb
42	¹¹⁰Mo
43	¹¹¹Tc
44	¹¹²Ru
45	¹¹³Rh	¹²⁶Rh
46	¹¹⁴Pd	¹²⁶Pd
47	¹¹⁵Ag	¹²⁶Ag
48	¹¹⁶Cd	¹²⁶Cd
49	¹¹⁷In	¹²⁶In
50	¹¹⁸Sn	¹²⁶Sn
51	¹¹⁹Sb	¹²⁶Sb
52	¹²⁰Te	¹²⁶Te
53	¹²¹I	¹²⁶I
54	¹²²Xe	¹²⁶Xe
55	¹²³Cs	¹²⁶Cs
56	¹²⁴Ba	¹²⁶Ba
57	¹²⁵La	¹²⁶La
58	¹²⁶Ce	¹²⁶Ce
59	¹²⁷Pr	¹²⁶Pr
60	¹²⁸Nd	¹²⁶Nd
61	¹²⁹Pm	¹²⁶Pm
62	¹³⁰Sm
63	¹³¹Eu

External data and identifiers

Adopted Levels, Gammas:NuDat 126Ce

Literature and References

[1] - D. D. Bogdanov, A. V. Demyanov, V. A. Karnaukhov et al.:
New neutron-deficient isotopes of lanthanum and cerium.
In: Nuclear Physics A, 307, 3, (1978), DOI 10.1016/0375-9474(78)90457-8.