Einsteinium-253

Properties and data of the isotope ²⁵³Es.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Einsteinium-253 is a radioisotope of the chemical element einsteinium, which has 154 neutrons in its atomic nucleus in addition to the element-specific 99 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 253. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ²⁵³Es is exclusively for academic purposes.

The experimental observation of the isotope ²⁵³Es was first reported in 1954. The starting material was plutonium-239, which was irradiated in a neutron flux [1]. The alpha spectra revealed activity with a particle energy of approximately 6.6 MeV, which was attributed to a nuclide of element 99. From the characteristic decay chain and systematic comparisons of the half-lives, it was identified as ²⁵³Es

This isotope is considered the one whose detection confirmed the existence of element 99.

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

General data

Name of the isotope:Einsteinium-253; Es-253Symbol:²⁵³Es or 25399EsMass number A:253 (= number of nucleons)Atomic number Z:99 (= number of protons)Neutrons N:154Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.5555555555556 (= neutron-proton ratio)Neutron excess (N-Z):55Isotopic mass:253.0848212(13) u (atomic weight of Einsteinium-253)Nuclide mass:253.0305197 u (calculated nuclear mass without electrons)Mass excess:79.01044 MeVMass defect:2.024254032 u (per nucleus)Nuclear binding energy:1885.58048528 MeV (per nucleus)
7.45288729 MeV (average binding energy per nucleon)Separation energy:S_N = 6.355(50) MeV (first neutron)
S_P = 4.3131(26) MeV (first proton)Half-life:20.47(3) dDecay constant λ:3.919167958982 × 10^-7 s^-1Specific activity α:9.328767392387 × 10⁺¹⁴ Bq g^-1
25212.884844291 Ci g^-1Spin and parity:
(nuclear angular momentum)7/2+Magnetic dipole moment:μ(μ_N) = 4.10(7)Quadrupole moment Q:6.7(8) barn (100 fm²)Nuclear g-factor:g_l = 1.1714285714286Year of discovery:1954

Radioactive Decay

Half-life T_½ = 20.47(3) d respectively 1.768608 × 10⁶ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²⁴⁹Bk	99.9999913 % %	6.73924(5) MeV
SZ	div	0.0000087 %

Starting nuclides and radioactive decay chain of einsteinium-253

Parent Nuclides

Direct parent isotopes are: ²⁵⁷Md, ²⁵³Fm, ²⁵³Cf.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 154) and isobaric (same nucleon number A = 253) with Einsteinium-253. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 154	Isobar A = 253
95	²⁴⁹Am
96	²⁵⁰Cm
97	²⁵¹Bk	²⁵³Bk
98	²⁵²Cf	²⁵³Cf
99	²⁵³Es	²⁵³Es
100	²⁵⁴Fm	²⁵³Fm
101	²⁵⁵Md	²⁵³Md
102	²⁵⁶No	²⁵³No
103	²⁵⁷Lr	²⁵³Lr
104	²⁵⁸Rf	²⁵³Rf
105	²⁵⁹Db
106	²⁶⁰Sg
107	²⁶¹Bh

External data and identifiers

Adopted Levels, Gammas:NuDat 253Es

Literature and References

[1] - S. G. Thompson, A. Ghiorso, B. G. Harvey, and G. R. Choppin:
Transcurium Isotopes Produced in the Neutron Irradiation of Plutonium.
In: Physical Review, 93, 908, (1954), DOI 10.1103/PhysRev.93.908.