Isotopes of livermorium

Livermorium (Lv) is an artificial element, and thus a standard atomic mass cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was ²⁹³Lv in 2000. There are four known radioisotopes from ²⁹⁰Lv to ²⁹³Lv. The longest-lived isotope is ²⁹³Lv with a half-life of 53 ms.

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)	daughter isotope(s)	nuclear spin
290Lv	116	174	290.19864(71)#	15(+26−6) ms	α	286Fl	0+
291Lv	116	175	291.20108(66)#	6.3(+116−25) ms	α	287Fl
292Lv	116	176	292.20174(91)#	18.0(+16−6) ms	α	288Fl	0+
293Lv	116	177	293.20449(60)#	53(+62−19) ms	α	289Fl

Notes

• Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
• Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC, which use expanded uncertainties.

Isotopes and nuclear properties

Nucleosynthesis

Target-projectile combinations leading to Z=116 compound nuclei

The below table contains various combinations of targets and projectiles which could be used to form compound nuclei with atomic number 116.

Target	Projectile	CN	Attempt result
142Ce	142Ce	284Lv	Reaction yet to be attempted
208Pb	82Se	290Lv	Failure to date
232Th	58Fe	290Lv	Reaction yet to be attempted
238U	54Cr	292Lv	Failure to date
244Pu	50Ti	294Lv	Reaction yet to be attempted
250Cm	48Ca	298Lv	Reaction yet to be attempted
248Cm	48Ca	296Lv	Successful reaction
246Cm	48Ca	294Lv	Reaction yet to be attempted
245Cm	48Ca	293Lv	Successful reaction
249Cf	40Ar	289Lv	Reaction yet to be attempted
252Cf	40Ar	292Lv	Reaction yet to be attempted
257Fm	36S	293Lv	Reaction yet to be attempted

Cold fusion

²⁰⁸Pb(⁸²Se,xn)^290−xLv

In 1998, the team at GSI attempted the synthesis of ²⁹⁰Lv as a radiative capture (x=0) product. No atoms were detected providing a cross section limit of 4.8 pb.

Hot fusion

This section deals with the synthesis of nuclei of livermorium by so-called "hot" fusion reactions. These are processes which create compound nuclei at high excitation energy (~40–50 MeV, hence "hot"), leading to a reduced probability of survival from fission. The excited nucleus then decays to the ground state via the emission of 3–5 neutrons. Fusion reactions utilizing ⁴⁸Ca nuclei usually produce compound nuclei with intermediate excitation energies (~30–35 MeV) and are sometimes referred to as "warm" fusion reactions. This leads, in part, to relatively high yields from these reactions.

²³⁸U(⁵⁴Cr,xn)^292−xLv

There are sketchy indications that this reaction was attempted by the team at GSI in 2006. There are no published results on the outcome, presumably indicating that no atoms were detected. This is expected from a study of the systematics of cross sections for ²³⁸U targets.

²⁴⁸Cm(⁴⁸Ca,xn)^296−xLv (x=3,4)

The first attempt to synthesise livermorium was performed in 1977 by Ken Hulet and his team at the Lawrence Livermore National Laboratory (LLNL). They were unable to detect any atoms of livermorium. Yuri Oganessian and his team at the Flerov Laboratory of Nuclear Reactions (FLNR) subsequently attempted the reaction in 1978 and were met by failure. In 1985, a joint experiment between Berkeley and Peter Armbruster's team at GSI, the result was again negative with a calculated cross-section limit of 10–100 pb.

In 2000, Russian scientists at Dubna finally succeeded in detecting a single atom of livermorium, assigned to the isotope ²⁹²Lv. In 2001, they repeated the reaction and formed a further 2 atoms in a confirmation of their discovery experiment. A third atom was tentatively assigned to ²⁹³Lv on the basis of a missed parental alpha decay. In April 2004, the team ran the experiment again at higher energy and were able to detect a new decay chain, assigned to ²⁹²Lv. On this basis, the original data were reassigned to ²⁹³Lv. The tentative chain is therefore possibly associated with a rare decay branch of this isotope. In this reaction, 2 further atoms of ²⁹³Lv were detected.

In an experiment run at the GSI during June–July 2010, scientists detected six atoms of Livermorium; two atoms of ²⁹³Lv and four atoms of ²⁹²Lv. They were able to confirm both the decay data and cross sections for the fusion reaction.

²⁴⁵Cm(⁴⁸Ca,xn)^293−xLv (x=2,3)

In order to assist in the assignment of isotope mass numbers for livermorium, in March–May 2003 the Dubna team bombarded a ²⁴⁵Cm target with ⁴⁸Ca ions. They were able to observe two new isotopes, assigned to ²⁹¹Lv and ²⁹⁰Lv.This experiment was successfully repeated in Feb–March 2005 where 10 atoms were created with identical decay data to those reported in the 2003 experiment.

As a decay product

Livermorium has also been observed in the decay of ununoctium. In October 2006 it was announced that 3 atoms of ununoctium had been detected by the bombardment of californium-249 with calcium-48 ions, which then rapidly decayed into livermorium.

The observation of ²⁹⁰Lv allowed the assignment of the product to ²⁹⁴Uuo and proved the synthesis of ununoctium.

Fission of compound nuclei with Z=116

Several experiments have been performed between 2000 and 2006 at the Flerov laboratory of Nuclear Reactions in Dubna studying the fission characteristics of the compound nuclei ^296,294,290Lv. Four nuclear reactions have been used, namely ²⁴⁸Cm+⁴⁸Ca, ²⁴⁶Ca+⁴⁸Ca,²⁴⁴Pu+⁵⁰Ti and ²³²Th+⁵⁸Fe. The results have revealed how nuclei such as this fission predominantly by expelling closed shell nuclei such as ¹³²Sn (Z=50, N=82). It was also found that the yield for the fusion-fission pathway was similar between ⁴⁸Ca and ⁵⁸Fe projectiles, indicating a possible future use of ⁵⁸Fe projectiles in superheavy element formation. In addition, in comparative experiments synthesizing ²⁹⁴Lv using ⁴⁸Ca and ⁵⁰Ti projectiles, the yield from fusion-fission was ~3x less for ⁵⁰Ti, also suggesting a future use in SHE production

Retracted isotopes

²⁸⁹Lv

In 1999, researchers at Lawrence Berkeley National Laboratory announced the synthesis of ²⁹³Uuo (see ununoctium), in a paper published in Physical Review Letters.The claimed isotope ²⁸⁹Lv decayed by 11.63 MeV alpha emission with a half-life of 0.64 ms. The following year, they published a retraction after other researchers were unable to duplicate the results. In June 2002, the director of the lab announced that the original claim of the discovery of these two elements had been based on data fabricated by the principal author Victor Ninov. As such, this isotope of livermorium is currently unknown.

Chronology of isotope discovery

Isotope	Year discovered	Discovery reaction
290Lv	2002	249Cf(48Ca,3n)
291Lv	2003	245Cm(48Ca,2n)
292Lv	2004	248Cm(48Ca,4n)
293Lv	2000	248Cm(48Ca,3n)

Yields of isotopes

Hot fusion

The table below provides cross-sections and excitation energies for hot fusion reactions producing livermorium isotopes directly. Data in bold represent maxima derived from excitation function measurements. + represents an observed exit channel.

Projectile	Target	CN	2n	3n	4n	5n
48Ca	248Cm	296Lv		1.1 pb, 38.9 MeV	3.3 pb, 38.9 MeV
48Ca	245Cm	293Lv	0.9 pb, 33.0 MeV	3.7 pb, 37.9 MeV

Theoretical calculations

Decay characteristics

Theoretical calculation in a quantum tunneling model supports the experimental data relating to the synthesis of ²⁹³Lv and ²⁹²Lv.

Evaporation residue cross sections

The below table contains various targets-projectile combinations for which calculations have provided estimates for cross section yields from various neutron evaporation channels. The channel with the highest expected yield is given.

DNS = Di-nuclear system; σ = cross section

Target	Projectile	CN	Channel (product)	σmax	Model	Ref
208Pb	82Se	290Lv	1n (289Lv)	0.1 pb	DNS
208Pb	79Se	287Lv	1n (286Lv)	0.5 pb	DNS
238U	54Cr	292Lv	2n (290Lv)	0.1 pb	DNS
250Cm	48Ca	298Lv	4n (294Lv)	5 pb	DNS
248Cm	48Ca	296Lv	4n (292Lv)	2 pb	DNS
247Cm	48Ca	295Lv	3n (292Lv)	3 pb	DNS
245Cm	48Ca	293Lv	3n (290Lv)	1.5 pb	DNS

References

• Isotope masses from:
• Isotopic compositions and standard atomic masses from:
• Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.

Isotopes of ununpentium	Isotopes of livermorium	Isotopes of ununseptium
Table of nuclides