Isotopes of livermorium

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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[edit]

nuclide
symbol
Z(p) N(n)  
isotopic mass (u)
 
half-life decay mode(s) daughter
isotope(s)
nuclear
spin
290Lv[n 1] 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
  1. ^ Not directly synthesized, created as decay product of 294Uuo

Notes[edit]

  • 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[edit]

Nucleosynthesis[edit]

Target-projectile combinations leading to Z=116 compound nuclei[edit]

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[edit]

208Pb(82Se,xn)290−xLv[edit]

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[edit]

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[edit]

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.[1]

248Cm(48Ca,xn)296−xLv (x=3,4)[edit]

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.[2] 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.[3]

In 2000, Russian scientists at Dubna finally succeeded in detecting a single atom of livermorium, assigned to the isotope 292Lv.[4] 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.[5] 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.[6]

In an experiment run at the GSI between 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.[citation needed]

245Cm(48Ca,xn)293−xLv (x=2,3)[edit]

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.[7]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.[8]

As a decay product[edit]

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.[8]

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[edit]

Several experiments have been performed between 2000–2006 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[9]

Retracted isotopes[edit]

289Lv[edit]

In 1999, researchers at Lawrence Berkeley National Laboratory announced the synthesis of 293Uuo (see ununoctium), in a paper published in Physical Review Letters.[10]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.[11] 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[edit]

Isotope Year discovered Discovery reaction
290Lv 2002 249Cf(48Ca,3n)[12]
291Lv 2003 245Cm(48Ca,2n)[7]
292Lv 2004 248Cm(48Ca,4n)[6]
293Lv 2000 248Cm(48Ca,3n)[4]

Yields of isotopes[edit]

Hot fusion[edit]

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[6] 3.3 pb, 38.9 MeV[6]
48Ca 245Cm 293Lv 0.9 pb, 33.0 MeV[7] 3.7 pb, 37.9 MeV[7]

Theoretical calculations[edit]

Decay characteristics[edit]

Theoretical calculation in a quantum tunneling model supports the experimental data relating to the synthesis of 293Lv and 292Lv.[13][14]

Evaporation residue cross sections[edit]

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 [15]
208Pb 79Se 287Lv 1n (286Lv) 0.5 pb DNS [15]
238U 54Cr 292Lv 2n (290Lv) 0.1 pb DNS [16]
250Cm 48Ca 298Lv 4n (294Lv) 5 pb DNS [16]
248Cm 48Ca 296Lv 4n (292Lv) 2 pb DNS [16]
247Cm 48Ca 295Lv 3n (292Lv) 3 pb DNS [16]
245Cm 48Ca 293Lv 3n (290Lv) 1.5 pb DNS [16]

References[edit]

  1. ^ "List of experiments 2000–2006"
  2. ^ Hulet, E. K.; Lougheed, R.; Wild, J.; Landrum, J.; Stevenson, P.; Ghiorso, A.; Nitschke, J.; Otto, R. et al. (1977). "Search for Superheavy Elements in the Bombardment of 248Cm with48Ca". Physical Review Letters 39 (7): 385. Bibcode:1977PhRvL..39..385H. doi:10.1103/PhysRevLett.39.385. 
  3. ^ Armbruster, P.; Agarwal, YK; Brüchle, W; Brügger, M; Dufour, JP; Gaggeler, H; Hessberger, FP; Hofmann, S et al. (1985). "Attempts to Produce Superheavy Elements by Fusion of 48Ca with 248Cm in the Bombarding Energy Range of 4.5–5.2 MeV/u". Physical Review Letters 54 (5): 406–409. Bibcode:1985PhRvL..54..406A. doi:10.1103/PhysRevLett.54.406. PMID 10031507. 
  4. ^ a b Oganessian, Yu. Ts.; Utyonkov, V.; Lobanov, Yu.; Abdullin, F.; Polyakov, A.; Shirokovsky, I.; Tsyganov, Yu.; Gulbekian, G.; Bogomolov, S.; Gikal, B.; Mezentsev, A.; Iliev, S.; Subbotin, V.; Sukhov, A.; Ivanov, O.; Buklanov, G.; Subotic, K.; Itkis, M.; Moody, K.; Wild, J.; Stoyer, N.; Stoyer, M.; Lougheed, R.; Laue, C.; Karelin, Ye.; Tatarinov, A. (2000). "Observation of the decay of ^{292}116". Physical Review C 63: 011301. Bibcode:2001PhRvC..63a1301O. doi:10.1103/PhysRevC.63.011301. 
  5. ^ "Confirmed results of the 248Cm(48Ca,4n)292116 experiment", Patin et al., LLNL report (2003). Retrieved 2008-03-03
  6. ^ a b c d Oganessian, Yu. Ts.; Utyonkov, V.; Lobanov, Yu.; Abdullin, F.; Polyakov, A.; Shirokovsky, I.; Tsyganov, Yu.; Gulbekian, G.; Bogomolov, S.; Gikal, B.; Mezentsev, A.; Iliev, S.; Subbotin, V.; Sukhov, A.; Voinov, A.; Buklanov, G.; Subotic, K.; Zagrebaev, V.; Itkis, M.; Patin, J.; Moody, K.; Wild, J.; Stoyer, M.; Stoyer, N.; Shaughnessy, D.; Kenneally, J.; Wilk, P.; Lougheed, R.; Il’Kaev, R.; Vesnovskii, S. (2004). "Measurements of cross sections and decay properties of the isotopes of elements 112, 114, and 116 produced in the fusion reactions ^{233,238}U, ^{242}Pu, and ^{248}Cm+^{48}Ca". Physical Review C 70 (6): 064609. Bibcode:2004PhRvC..70f4609O. doi:10.1103/PhysRevC.70.064609. 
  7. ^ a b c d Oganessian, Yu. Ts.; Utyonkov, V.; Lobanov, Yu.; Abdullin, F.; Polyakov, A.; Shirokovsky, I.; Tsyganov, Yu.; Gulbekian, G. et al. (2004). "Measurements of cross sections for the fusion-evaporation reactions244Pu(48Ca,xn)292−x114 and 245Cm(48Ca,xn)293−x116". Physical Review C 69 (5): 054607. Bibcode:2004PhRvC..69e4607O. doi:10.1103/PhysRevC.69.054607. 
  8. ^ a b Synthesis of the isotopes of elements 118 and 116 in the 249Cf and 245Cm+48Ca fusion reactions. 
  9. ^ see Flerov lab annual reports 2000–2006
  10. ^ Ninov, V.; et al. (1999). "Observation of Superheavy Nuclei Produced in the Reaction of86Kr with 208Pb". Physical Review Letters 83 (6): 1104. Bibcode:1999PhRvL..83.1104N. doi:10.1103/PhysRevLett.83.1104. 
  11. ^ Ninov, V.; Gregorich, K.; Loveland, W.; Ghiorso, A.; Hoffman, D.; Lee, D.; Nitsche, H.; Swiatecki, W.; Kirbach, U.; Laue, C.; Adams, J.; Patin, J.; Shaughnessy, D.; Strellis, D.; Wilk, P. (2002). "Editorial Note: Observation of Superheavy Nuclei Produced in the Reaction of ^{86}Kr with ^{208}Pb [Phys. Rev. Lett. 83, 1104 (1999)]". Physical Review Letters 89 (3): 039901. Bibcode:2002PhRvL..89c9901N. doi:10.1103/PhysRevLett.89.039901. 
  12. ^ see ununoctium
  13. ^ P. Roy Chowdhury, C. Samanta, and D. N. Basu (2006). "α decay half-lives of new superheavy elements". Phys. Rev. C 73: 014612. arXiv:nucl-th/0507054. Bibcode:2006PhRvC..73a4612C. doi:10.1103/PhysRevC.73.014612. 
  14. ^ C. Samanta, P. Roy Chowdhury and D.N. Basu (2007). "Predictions of alpha decay half lives of heavy and superheavy elements". Nucl. Phys. A 789: 142–154. arXiv:nucl-th/0703086. Bibcode:2007NuPhA.789..142S. doi:10.1016/j.nuclphysa.2007.04.001. 
  15. ^ a b Feng, Zhao-Qing; Jin, Gen-Ming; Li, Jun-Qing; Scheid, Werner (2007). "Formation of superheavy nuclei in cold fusion reactions". Physical Review C 76 (4): 044606. arXiv:0707.2588. Bibcode:2007PhRvC..76d4606F. doi:10.1103/PhysRevC.76.044606. 
  16. ^ a b c d e Feng, Z; Jin, G; Li, J; Scheid, W (2009). "Production of heavy and superheavy nuclei in massive fusion reactions". Nuclear Physics A 816: 33. arXiv:0803.1117. Bibcode:2009NuPhA.816...33F. doi:10.1016/j.nuclphysa.2008.11.003. 


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