Uranium-227

Properties and data of the isotope ²²⁷U.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Uranium-227 is a radioisotope of the chemical element uranium, which has 135 neutrons in its atomic nucleus in addition to the element-specific 92 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 227. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ²²⁷U is exclusively for academic purposes.

The radioactive isotope U-223 was discovered in 1951 [1].

Synthetically, ²²⁷U can be prepared by the following reaction: ²⁰⁸Pb(²²Ne,3n)²²⁷U (110 MeV beam energy).

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

General data

Name of the isotope:Uranium-227; U-227Symbol:²²⁷U or 22792UMass number A:227 (= number of nucleons)Atomic number Z:92 (= number of protons)Neutrons N:135Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.4673913043478 (= neutron-proton ratio)Neutron excess (N-Z):43Isotopic mass:227.031182(10) u (atomic weight of Uranium-227)Nuclide mass:226.9807193 u (calculated nuclear mass without electrons)Mass excess:29.04585 MeVMass defect:1.858484604 u (per nucleus)Nuclear binding energy:1731.16725772 MeV (per nucleus)
7.62628748 MeV (average binding energy per nucleon)Separation energy:S_N = 6.355(16) MeV (first neutron)
S_P = 4.277(15) MeV (first proton)Half-life:1.1(1) minDecay constant λ:0.010502230008484 s^-1Specific activity α:2.786163368041 × 10⁺¹⁹ Bq g^-1
753017126.49773 Ci g^-1Spin and parity:
(nuclear angular momentum)(3/2+)Year of discovery:1952

Radioactive Decay

Uranium-227 decays to Thorium-223 by emitting α-particles (helium-4 nuclei).

Half-life T_½ = 1.1(1) min (minutes) respectively 6.6 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²²³Th	100 %	7.235(3) MeV	0.247 MeV (20 %)

Parent Nuclides

Direct parent isotope is: ²³¹Pu.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 135) and isobaric (same nucleon number A = 227) with Uranium-227. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 135	Isobar A = 227
80	²¹⁵Hg
81	²¹⁶Tl
82	²¹⁷Pb
83	²¹⁸Bi
84	²¹⁹Po	²²⁷Po
85	²²⁰At	²²⁷At
86	²²¹Rn	²²⁷Rn
87	²²²Fr	²²⁷Fr
88	²²³Ra	²²⁷Ra
89	²²⁴Ac	²²⁷Ac
90	²²⁵Th	²²⁷Th
91	²²⁶Pa	²²⁷Pa
92	²²⁷U	²²⁷U
93	²²⁸Np	²²⁷Np
94	²²⁹Pu
95	²³⁰Am

External data and identifiers

Adopted Levels, Gammas:NuDat 227U

Literature and References

[1] - W. W. Meinke, A. Ghiorso, G. T. Seaborg:
Further Work on Heavy Collateral Radioactive Chains.
In: Physical Review, 85, 429, (1952), DOI 10.1103/PhysRev.85.429.