Carbon-22

Properties and data of the isotope ²²C.

Contents

Carbon-22 is a radioisotope of the chemical element carbon, which has 16 neutrons in its atomic nucleus in addition to the element-specific 6 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 22. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ²²C is exclusively for academic purposes.

The discovery and identification of the radioactive isotope was reported in 1986: According to this, ²²C was produced as a product of the fragmentation of argon-40 (44 MeV/u) on a template of tantalum-181 [1].

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

General data

Name of the isotope:Carbon-22; C-22Symbol:²²C or 226CMass number A:22 (= number of nucleons)Atomic number Z:6 (= number of protons)Neutrons N:16Nucleon pairing (Z - N):even - evenNuclear ratio (N/Z ratio):2.6666666666667 (= neutron-proton ratio)Neutron excess (N-Z):10Isotopic mass:22.05755(25) u (atomic weight of Carbon-22)Nuclide mass:22.0542585 u (calculated nuclear mass without electrons)Mass excess:53.60748 MeVMass defect:0.128038848 u (per nucleus)Nuclear binding energy:119.26741868 MeV (per nucleus)
5.4212463 MeV (average binding energy per nucleon)Separation energy:S_N = 0.103(640) MeV (first neutron)
S_P = 32.061(605) MeV (first proton)Half-life:6.2(1.3) msDecay constant λ:113.6306853377 s^-1Specific activity α:3.11045451415 × 10⁺²⁴ Bq g^-1
84066338220486 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Charge radius:2.635 femtometer fmMatter radius:3.289 femtometer fmYear of discovery:1986

Radioactive Decay

Half-life T_½ = 6.2(1.3) ms respectively 6.1 × 10^-3 seconds s.

Decay mode	Daughter	Probability
β^-	²²N	> 2 %
β^-, n	²¹N	61(14) %
β^-, 2n	²⁰N	< 37 %

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 16) and isobaric (same nucleon number A = 22) with Carbon-22. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 16	Isobar A = 22
5	²¹B
6	²²C	²²C
7	²³N	²²N
8	²⁴O	²²O
9	²⁵F	²²F
10	²⁶Ne	²²Ne
11	²⁷Na	²²Na
12	²⁸Mg	²²Mg
13	²⁹Al	²²Al
14	³⁰Si	²²Si
15	³¹P
16	³²S
17	³³Cl
18	³⁴Ar
19	³⁵K
20	³⁶Ca
21	³⁷Sc
22	³⁸Ti

External data and identifiers

Adopted Levels, Gammas:NuDat 22C

Literature and References

[1] - F. Pougheon et al.:
First Observation of the Exotic Nucleus ²²C.
In: Europhysics Letters, 2(7), 505, (1986), DOI 10.1209/0295-5075/2/7/003.

[2] - Xiang-Xiang Sun, Jie Zhao, Shan-Gui Zhou:
Shrunk halo and quenched shell gap at N = 16 in ²²C: Inversion of sd states and deformation effects.
In: Physics Letters B, 785, 530-535, (2018), DOI 10.1016/j.physletb.2018.08.071.

[3] - Yasuhiro Togano:
Matter Radius of Two-neutron Halo Nucleus ²²C.
In: JPS Conference Proceedings, 32, 010030, (2020), DOI 10.7566/JPSCP.32.010030.