Aluminium-24

Properties and data of the isotope ²⁴Al.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Aluminium-24 is a radioisotope of the chemical element aluminium, which has 11 neutrons in its atomic nucleus in addition to the element-specific 13 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 24. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ²⁴Al is exclusively for academic purposes.

The first observation of the proton-rich isotope was reported in 1953 [1]: According to this, aluminium was formed by irradiating magnesium-24 with 20 MeV protons in a charge exchange reaction:

²⁴Mg(p,n)²⁴Al.

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

General data

Name of the isotope:Aluminium-24; Al-24Symbol:²⁴Al or 2413AlMass number A:24 (= number of nucleons)Atomic number Z:13 (= number of protons)Neutrons N:11Nucleon pairing (Z - N):odd - oddNuclear ratio (N/Z ratio):0.84615384615385 (= neutron-proton ratio)Neutron excess (N-Z):-2Isotopic mass:23.99994760(24) u (atomic weight of Aluminium-24)Nuclide mass:23.9928161 u (calculated nuclear mass without electrons)Mass excess:-0.04881 MeVMass defect:0.197091892 u (per nucleus)Nuclear binding energy:183.58991485 MeV (per nucleus)
7.64957979 MeV (average binding energy per nucleon)Separation energy:S_N = 14.8682(4) MeV (first neutron)
S_P = 1.86411(23) MeV (first proton)Half-life:2.053(4) sDecay constant λ:0.33762648833899 s^-1Specific activity α:8.840149003579 × 10⁺²¹ Bq g^-1
238922946042.68 Ci g^-1Spin and parity:
(nuclear angular momentum)4+Mirror nucleus:Sodium-24Year of discovery:1953

Radioactive Decay

Half-life T_½ = 2.053(4) s.

Decay mode	Daughter	Probability	Decay energy
EC/β⁺	²⁴Mg	99.96 %	13.88477(23) MeV
β⁺, p	²³Na	0.0016(3) %	2.19202(23) MeV
β⁺, α	²⁰Ne	0.035(6) %	4,560 MeV

Parent Nuclides

Direct parent isotope is: ²⁴Si.

Nuclear Isomers

Nuclear isomers or excited states with the activation energy in keV related to the ground state.

Nuclear Isomer	Excitation Energy	Half-life	Spin
^24mAl	425.81(10) keV	130.7(13) ms	1+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 11) and isobaric (same nucleon number A = 24) with Aluminium-24. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 11	Isobar A = 24
4	¹⁵Be
5	¹⁶B
6	¹⁷C
7	¹⁸N	²⁴N
8	¹⁹O	²⁴O
9	²⁰F	²⁴F
10	²¹Ne	²⁴Ne
11	²²Na	²⁴Na
12	²³Mg	²⁴Mg
13	²⁴Al	²⁴Al
14	²⁵Si	²⁴Si
15	²⁶P	²⁴P
16	²⁷S
17	²⁸Cl
18	²⁹Ar

External data and identifiers

Adopted Levels, Gammas:NuDat 24Al

Literature and References

[1] - Neel W. Glass, Louis K. Jensen, J. Reginald Richardson:
The Short-Lived Radioisotopes P²⁸ and Cl³².
In: Physical Review, 90, 320, (1953), DOI 10.1103/PhysRev.90.320.2.

[2] - S. W. Breckon, A. Henrikson, J. S. Foster, W. M. Martin:
The Radioactive Isotopes Al²⁴, P²⁸, Cl³².
In: Canadian Journal of Physics, 32, 3, (1954), DOI 10.1139/p54-020.