Phosphorus-26

Properties and data of the isotope ²⁶P.

Contents

Phosphorus-26 is a radioisotope of the chemical element phosphorus, which has 11 neutrons in its atomic nucleus in addition to the element-specific 15 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 26. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ²⁶P is exclusively for academic purposes.

The isotope was first described in 1983 [1]; according to this, phosphorus-26 could be produced by irradiating silicon-28 with helium-3 ions of an energy of 110 to 130 MeV:

²⁸Si(³He,p4n)²⁶P.

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

General data

Name of the isotope:Phosphorus-26; P-26Symbol:²⁶P or 2615PMass number A:26 (= number of nucleons)Atomic number Z:15 (= number of protons)Neutrons N:11Nucleon pairing (Z - N):odd - oddNuclear ratio (N/Z ratio):0.73333333333333 (= neutron-proton ratio)Neutron excess (N-Z):-4Isotopic mass:26.01178(21) u (atomic weight of Phosphorus-26)Nuclide mass:26.0035514 u (calculated nuclear mass without electrons)Mass excess:10.973 MeVMass defect:0.200909556 u (per nucleus)Nuclear binding energy:187.14604596 MeV (per nucleus)
7.19792484 MeV (average binding energy per nucleon)Separation energy:S_N = 17.288(445) MeV (first neutron)
S_P = 0.143(196) MeV (first proton)Half-life:43.7(6) msDecay constant λ:15.861491545994 s^-1Specific activity α:3.673851397641 × 10⁺²³ Bq g^-1
9929328101733.2 Ci g^-1Spin and parity:
(nuclear angular momentum)(3)+Isobaric spin: 2Mirror nucleus:Sodium-26Year of discovery:1983

Radioactive Decay

Half-life T_½ = 43.7(6) ms respectively 4.37 × 10^-2 seconds s.

Decay mode	Daughter	Probability	Decay energy
EC/β⁺	²⁶Si	62.9 %	18.114(196) MeV
β⁺, p	²⁵Al	35.1 %	12.600 MeV
β⁺, 2p	²⁴Mg	1.99 %	10,329 MeV

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
^26mP	164.4(1) keV	115(8) ns	(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 = 26) with Phosphorus-26. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

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

External data and identifiers

Adopted Levels, Gammas:NuDat 26P

Literature and References

[1] - M. D. Cable, J. Honkanen, R. F. Parry et al.:
Beta-delayed proton decay of the T_Z = -2 isotope ²⁶P.
In: Physics Letters B, 123, 1-2, (1983), DOI 10.1016/0370-2693(83)90950-4.

[2] - Zhongzhou Ren, Baoqiu Chen, Zhongyu Ma, Gongou Xu:
One-proton halo in ²⁶P and two-proton halo in ²⁷S.
In: Physical Review C, (1996), DOI 10.1103/PhysRevC.53.R572.

[3] - D. Pérez-Loureiro et al.:
β-delayed γ decay of ²⁶P: Possible evidence of a proton halo.
In: Physical Review C, 93, 064320, (2016), DOI 10.1103/PhysRevC.93.064320.