نظائر التنسين

نظائر tennessine (117Ts)
النظائر الرئيسية[1] اضمحلال
توا­فر عمر النصف (t1/2) النمط نا­تج
293Ts synth 25 ms[1][2] α 289Mc
294Ts synth 51 ms[3] α 290Mc

Tennessine (117Ts) is the most-recently synthesized synthetic element, and much of the data is hypothetical. As for any synthetic element, a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first (and so far only) isotopes to be synthesized were 293Ts and 294Ts in 2009. The longer-lived isotope is 294Ts with a half-life of 51 ms.

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List of isotopes

Nuclide
 Z N Isotopic mass (Da)[4]
[n 1][n 2] 		Half-life
 Decay
mode
 Daughter
isotope
 Spin and
parity
293Ts 117 176 293.20873(84)# 22+8
−4 ms[3] 		α 289Mc
294Ts 117 177 294.21084(64)# 51+41
−16 ms[2] 		α 290Mc
This table header & footer:  view 
  1. ^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  2. ^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).


Isotopes and nuclear properties

Nucleosynthesis

Target-projectile combinations leading to Z=117 compound nuclei

The below table contains various combinations of targets and projectiles that could be used to form compound nuclei with atomic number 117.

Target Projectile CN Attempt result
208Pb 81Br 289Ts Yet to be attempted
209Bi 82Se 291Ts Yet to be attempted
238U 55Mn 293Ts Yet to be attempted
243Am 50Ti 293Ts Yet to be attempted
249Bk 48Ca 297Ts Successful reaction

Hot fusion

249Bk(48Ca,xn)297−xTs (x=3,4)

Between July 2009 and February 2010, the team at the JINR (Flerov Laboratory of Nuclear Reactions) ran a 7-month-long experiment to synthesize tennessine using the reaction above.[5] The expected cross-section was of the order of 2 pb. The expected evaporation residues, 293Ts and 294Ts, were predicted to decay via relatively long decay chains as far as isotopes of dubnium or lawrencium.

  • Calculated decay chains from the parent nuclei 293Ts and 294Ts[6]

    Calculated decay chains from the parent nuclei 293Ts and 294Ts[6]


The team published a paper in April 2010 (first results were presented in January 2010[7]) that six atoms of the isotopes 294Ts (one atom) and 293Ts (five atoms) were detected. 294Ts decayed by six alpha decays down as far as the new isotope 270Db, which underwent apparent spontaneous fission. The lighter odd-even isotope underwent just three alpha decays, as far as 281Rg, which underwent spontaneous fission. The reaction was run at two different excitation energies, 35 MeV (dose 2×1019) and 39 MeV (dose 2.4×1019). Initial decay data was published as a preliminary presentation on the JINR website.[8]

A further experiment in May 2010, aimed at studying the chemistry of the granddaughter of tennessine, nihonium, identified a further two atoms of 286Nh from decay of 294Ts. The original experiment was repeated successfully by the same collaboration in 2012 and by a joint German–American team in May 2014, confirming the discovery.

Chronology of isotope discovery

Isotope Year discovered Reaction
294Ts 2009 249Bk(48Ca,3n)
293Ts 2009 249Bk(48Ca,4n)

Theoretical calculations

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
209Bi 82Se 291Ts 1n (290Ts) 15 fb DNS [9]
209Bi 79Se 288Ts 1n (287Ts) 0.2 pb DNS [9]
232Th 59Co 291Ts 2n (289Ts) 0.1 pb DNS [9]
238U 55Mn 293Ts 2-3n (291,290Ts) 70 fb DNS [9]
244Pu 51V 295Ts 3n (292Ts) 0.6 pb DNS [9]
248Cm 45Sc 293Ts 4n (289Ts) 2.9 pb DNS [9]
246Cm 45Sc 291Ts 4n (287Ts) 1 pb DNS [9]
249Bk 48Ca 297Ts 3n (294Ts) 2.1 pb ; 3 pb DNS [9][10]
247Bk 48Ca 295Ts 3n (292Ts) 0.8, 0.9 pb DNS [9][10]

Decay characteristics

Theoretical calculations in a quantum tunneling model with mass estimates from a macroscopic-microscopic model predict the alpha-decay half-lives of isotopes of tennessine (namely, 289–303Ts) to be around 0.1–40 ms.[11][12][13]

References

  1. ^ أ ب Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  2. ^ أ ب Khuyagbaatar, J.; Yakushev, A.; Düllmann, Ch. E.; et al. (2014). "48Ca+249Bk Fusion Reaction Leading to Element Z=117: Long-Lived α-Decaying 270Db and Discovery of 266Lr". Physical Review Letters. 112 (17): 172501. Bibcode:2014PhRvL.112q2501K. doi:10.1103/PhysRevLett.112.172501. PMID 24836239.
  3. ^ أ ب Oganessian, Yu. Ts.; et al. (2013). "Experimental studies of the 249Bk + 48Ca reaction including decay properties and excitation function for isotopes of element 117, and discovery of the new isotope 277Mt". Physical Review C. 87 (5): 054621. Bibcode:2013PhRvC..87e4621O. doi:10.1103/PhysRevC.87.054621.
  4. ^ Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
  5. ^ Tennessine – the 117th element at AtomInfo.ru
  6. ^ Roman Sagaidak. "Experiment setting on synthesis of superheavy nuclei in fusion-evaporation reactions. Preparation to synthesis of new element with Z=117" (PDF). Archived from the original (PDF) on 2011-07-03. Retrieved 2009-07-07.
  7. ^ Recommendations: 31st meeting, PAC for Nuclear Physics Archived 2010-04-14 at the Wayback Machine
  8. ^ Walter Grenier: Recommendations, a PowerPoint presentation at the January 2010 meeting of the PAC for Nuclear Physics
  9. ^ أ ب ت ث ج ح خ د ذ Zhao-Qing, Feng; Gen-Ming, Jin; Ming-Hui, Huang; Zai-Guo, Gan; Nan, Wang; Jun-Qing, Li (2007). "Possible Way to Synthesize Superheavy Element Z = 117". Chinese Physics Letters. 24 (9): 2551. arXiv:0708.0159. Bibcode:2007ChPhL..24.2551F. doi:10.1088/0256-307X/24/9/024. S2CID 250860387.
  10. ^ أ ب Feng, Z; Jin, G; Li, J; Scheid, W (2009). "Production of heavy and superheavy nuclei in massive fusion reactions". Nuclear Physics A. 816 (1–4): 33. arXiv:0803.1117. Bibcode:2009NuPhA.816...33F. doi:10.1016/j.nuclphysa.2008.11.003. S2CID 18647291.
  11. ^ C. Samanta; P. Roy Chowdhury; D. N. Basu (2007). "Predictions of alpha decay half lives of heavy and superheavy elements". Nuclear Physics A. 789 (1–4): 142–154. arXiv:nucl-th/0703086. Bibcode:2007NuPhA.789..142S. doi:10.1016/j.nuclphysa.2007.04.001. S2CID 7496348.
  12. ^ P. Roy Chowdhury; C. Samanta; D. N. Basu (2008). "Search for long lived heaviest nuclei beyond the valley of stability". Physical Review C. 77 (4): 044603. arXiv:0802.3837. Bibcode:2008PhRvC..77d4603C. doi:10.1103/PhysRevC.77.044603. S2CID 119207807.
  13. ^ P. Roy Chowdhury; C. Samanta; D. N. Basu (2008). "Nuclear half-lives for α -radioactivity of elements with 100 ≤ Z ≤ 130". Atomic Data and Nuclear Data Tables. 94 (6): 781–806. arXiv:0802.4161. Bibcode:2008ADNDT..94..781C. doi:10.1016/j.adt.2008.01.003. S2CID 96718440.
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