Cerium-128

Properties and data of the isotope ¹²⁸Ce.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Cerium-128 is a radioisotope of the chemical element cerium, which has 70 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 128. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ¹²⁸Ce is exclusively for academic purposes.

Cerium-128 was first described in 1968. The isotope was produced in fusion-evaporation reactions in which tin-116 targets were bombarded with an 80 MeV oxygen-16 beam and cadmium-112 targets with a 90 MeV neon-20 beam: ¹¹⁶Sn(¹⁶O,4n)¹²⁸Ce and ¹¹²Cd(²⁰Ne,4n)¹²⁸Ce [1]. The publication does not explicitly mention the discovery of the isotope; however, it is considered the first experimental identification.

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

General data

Name of the isotope:Cerium-128; Ce-128Symbol:¹²⁸Ce or 12858CeMass number A:128 (= number of nucleons)Atomic number Z:58 (= number of protons)Neutrons N:70Nucleon pairing (Z - N):even - evenNuclear ratio (N/Z ratio):1.2068965517241 (= neutron-proton ratio)Neutron excess (N-Z):12Isotopic mass:127.91891(3) u (atomic weight of Cerium-128)Nuclide mass:127.8870946 u (calculated nuclear mass without electrons)Mass excess:-75.53485 MeVMass defect:1.141485976 u (per nucleus)Nuclear binding energy:1063.28733773 MeV (per nucleus)
8.30693233 MeV (average binding energy per nucleon)Separation energy:S_N = 11.626(40) MeV (first neutron)
S_P = 4.927(38) MeV (first proton)Half-life:3.93(2) minDecay constant λ:0.0029395554731126 s^-1Specific activity α:1.393891112179 × 10⁺¹⁹ Bq g^-1
376727327.61614 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Year of discovery:1968

Radioactive Decay

Half-life T_½ = 3.93(2) min (minutes) respectively 2.358 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC/β⁺	¹²⁸La	100 %	3.092(61) MeV

Parent Nuclides

Direct parent isotope is: ¹²⁸Pr.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 70) and isobaric (same nucleon number A = 128) with Cerium-128. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 70	Isobar A = 128
39	¹⁰⁹Y
40	¹¹⁰Zr
41	¹¹¹Nb
42	¹¹²Mo
43	¹¹³Tc
44	¹¹⁴Ru
45	¹¹⁵Rh
46	¹¹⁶Pd	¹²⁸Pd
47	¹¹⁷Ag	¹²⁸Ag
48	¹¹⁸Cd	¹²⁸Cd
49	¹¹⁹In	¹²⁸In
50	¹²⁰Sn	¹²⁸Sn
51	¹²¹Sb	¹²⁸Sb
52	¹²²Te	¹²⁸Te
53	¹²³I	¹²⁸I
54	¹²⁴Xe	¹²⁸Xe
55	¹²⁵Cs	¹²⁸Cs
56	¹²⁶Ba	¹²⁸Ba
57	¹²⁷La	¹²⁸La
58	¹²⁸Ce	¹²⁸Ce
59	¹²⁹Pr	¹²⁸Pr
60	¹³⁰Nd	¹²⁸Nd
61	¹³¹Pm	¹²⁸Pm
62	¹³²Sm	¹²⁸Sm
63	¹³³Eu
64	¹³⁴Gd
65	¹³⁵Tb

External data and identifiers

Adopted Levels, Gammas:NuDat 128Ce

Literature and References

[1] - David Ward, R.M. Diamond, F.S. Stephens:
Collective levels in light even Ce isotopes.
In: Nuclear Physics A, 117, 2, (1968), DOI 10.1016/0375-9474(68)90845-2.