Hassium-265

Properties and data of the isotope ²⁶⁵Hs.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Hassium-265 is a radioisotope of the chemical element hassium, which has 157 neutrons in its atomic nucleus in addition to the element-specific 108 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 265. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ²⁶⁵Hs is exclusively for academic purposes.

In 1984, the discovery of the isotope hassium-265 was reported [1]: In the described experiment, an enriched lead-208 target was irradiated with an iron-58 beam at an energy of 5.02 MeV per nucleon. The isotope was produced in the fusion-evaporation reaction ²⁰⁸Pb(⁵⁸Fe,n)²⁶⁵Hs.

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

General data

Name of the isotope:Hassium-265; Hs-265Symbol:²⁶⁵Hs or 265108HsMass number A:265 (= number of nucleons)Atomic number Z:108 (= number of protons)Neutrons N:157Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.4537037037037 (= neutron-proton ratio)Neutron excess (N-Z):49Isotopic mass:265.129792(26) u (atomic weight of Hassium-265)Nuclide mass:265.0705551 u (calculated nuclear mass without electrons)Mass excess:120.90047 MeVMass defect:2.075703268 u (per nucleus)Nuclear binding energy:1933.50513992 MeV (per nucleus)
7.29624581 MeV (average binding energy per nucleon)Separation energy:S_N = 6.734(38) MeV (first neutron)
S_P = 2.346(179) MeV (first proton)Half-life:1.96(16) msDecay constant λ:353.64652069385 s^-1Specific activity α:8.03663834809 × 10⁺²³ Bq g^-1
21720644184038 Ci g^-1Spin and parity:
(nuclear angular momentum)3/2+Year of discovery:1984

Radioactive Decay

Half-life T_½ = 1.96(16) ms respectively 1.96 × 10^-3 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²⁶¹Sg	100 %	10.470(15) MeV
SZ	div	?

Production and radioactive decay chain of hassium-265

Parent Nuclides

Direct parent isotope is: ²⁶⁹Ds.

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
^265mHs	300 keV	0.75 ms	3/2+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 157) and isobaric (same nucleon number A = 265) with Hassium-265. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 157	Isobar A = 265
97	²⁵⁴Bk
98	²⁵⁵Cf
99	²⁵⁶Es
100	²⁵⁷Fm
101	²⁵⁸Md
102	²⁵⁹No
103	²⁶⁰Lr	²⁶⁵Lr
104	²⁶¹Rf	²⁶⁵Rf
105	²⁶²Db	²⁶⁵Db
106	²⁶³Sg	²⁶⁵Sg
107	²⁶⁴Bh	²⁶⁵Bh
108	²⁶⁵Hs	²⁶⁵Hs
109	²⁶⁶Mt
110	²⁶⁷Ds

External data and identifiers

Adopted Levels, Gammas:NuDat 265Hs

Literature and References

[1] - G. Münzenberg, P. Armbruster, H. Folger, P. F. Heßberger, S. Hofmann et al.:
The identification of element 108.
In: Zeitschrift für Physik A, 317, (1984), DOI 10.1007/BF01421260.

[2] - Nozomi Sato et al.:
Production and Decay Properties of ²⁶⁴Hs and ²⁶⁵Hs.
In: Journal of the Physical Society of Japan, 80, 9, (2011), DOI 10.1143/JPSJ.80.094201.