Gadolinium-136

Properties and data of the isotope ¹³⁶Gd.

Contents

Gadolinium-136 is a radioisotope of the chemical element gadolinium, which has 72 neutrons in its atomic nucleus in addition to the element-specific 64 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 136. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ¹³⁶Gd is exclusively for academic purposes.

Gd-136 was first mentioned in a conference report from 2000; according to this, the isotope was observed as a fragmentation product during the irradiation of a zirconium-90 target with gold-197 (30 MeV per nucleon) [1]. A more recent report, published in 2026, describes the production and identification of gadolinium-136 during the irradiation of a 1 mm thick beryllium target with uranium-238 particles (345 MeV/nucleon) [2].

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

General data

Name of the isotope:Gadolinium-136; Gd-136Symbol:¹³⁶Gd or 13664GdMass number A:136 (= number of nucleons)Atomic number Z:64 (= number of protons)Neutrons N:72Nucleon pairing (Z - N):even - evenNuclear ratio (N/Z ratio):1.125 (= neutron-proton ratio)Neutron excess (N-Z):8Isotopic mass:135.94730(32) u (atomic weight of Gadolinium-136)Nuclide mass:135.9121937 u (calculated nuclear mass without electrons)Mass excess:-49.08973 MeVMass defect:1.177376 u (per nucleus)Nuclear binding energy:1096.71867974 MeV (per nucleus)
8.06410794 MeV (average binding energy per nucleon)Separation energy:S_N = 12.911(499) MeV (first neutron)
S_P = 2.231(357) MeV (first proton)Half-life:> 310 nsDecay constant λ:2235958.6469676 s^-1Specific activity α:9.904762879128 × 10⁺²⁷ Bq g^-1
2.676962940305 × 10⁺¹⁷ Ci g^-1Spin and parity:
(nuclear angular momentum)0+Year of discovery:2000

Radioactive Decay

Half-life T_½ = > 310 ns respectively 3.1 × 10^-7 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC β⁺	¹³⁶Eu	?	7.154(358) MeV
β⁺, p ?	¹³⁵Sm

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 72) and isobaric (same nucleon number A = 136) with Gadolinium-136. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 72	Isobar A = 136
39	¹¹¹Y
40	¹¹²Zr
41	¹¹³Nb
42	¹¹⁴Mo
43	¹¹⁵Tc
44	¹¹⁶Ru
45	¹¹⁷Rh
46	¹¹⁸Pd
47	¹¹⁹Ag
48	¹²⁰Cd
49	¹²¹In	¹³⁶In
50	¹²²Sn	¹³⁶Sn
51	¹²³Sb	¹³⁶Sb
52	¹²⁴Te	¹³⁶Te
53	¹²⁵I	¹³⁶I
54	¹²⁶Xe	¹³⁶Xe
55	¹²⁷Cs	¹³⁶Cs
56	¹²⁸Ba	¹³⁶Ba
57	¹²⁹La	¹³⁶La
58	¹³⁰Ce	¹³⁶Ce
59	¹³¹Pr	¹³⁶Pr
60	¹³²Nd	¹³⁶Nd
61	¹³³Pm	¹³⁶Pm
62	¹³⁴Sm	¹³⁶Sm
63	¹³⁵Eu	¹³⁶Eu
64	¹³⁶Gd	¹³⁶Gd
65	¹³⁷Tb	¹³⁶Tb
66	¹³⁸Dy