Isotopes of Ununseptium - Wikipedia, The Free Encyclopedia

From Wikipedia, the free encyclopedia

Ununseptium (Uus) is the most-recently synthesized artificial element, and much of the data is hypothetical. Asany artificial element, a standard atomic mass cannot be given. Like all artificial elements, it has no stableisotopes. The first (and so far only) isotopes to be synthesized were 293Uus and 294Uus in 2009. The longer-livedisotope is 294Uus with a half-life of 78 ms.

1 Table1.1 Notes

2 Isotopes and nuclear properties2.1 Nucleosynthesis

2.1.1 Target-projectile combinations leading to Z=117 compound nuclei2.1.2 Hot fusion

2.1.2.1 249Bk (48Ca, xn)297-xUus (x=3,4)2.1.3 Chronology of isotope discovery

2.2 Theoretical calculations2.2.1 Evaporation residue cross sections2.2.2 Decay characteristics

3 References4 External sources

nuclidesymbol Z(p) N(n)

isotopic mass (u)

half-life decay mode(s) daughter

isotope(s)nuclear

spin

293Uus 117 176 293.20824(89)# 14 (+11, -4) ms[1] α 289Uup294Uus 117 177 294.21046(74)# 78 (+370, -36) ms[1] α 290Uup

Notes

Values marked # are not purely derived from experimental data, but at least partly from systematic trends.Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertaintyvalues from Ame2003 denote one standard deviation. Values from IUPAC are expanded uncertainties.

Nucleosynthesis

Target-projectile combinations leading to Z=117 compound nuclei

Isotopes of ununseptium - Wikipedia, the free encyclopedia http://en.wikipedia.org/wiki/Isotopes_of_ununseptium

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

Target Projectile CN Attempt result153Eu 136Xe 289Uus Reaction yet to be attempted208Pb 81Br 289Uus Reaction yet to be attempted209Bi 82Se 291Uus Reaction yet to be attempted232Th 59Co 291Uus Reaction yet to be attempted231Pa 58Fe 289Uus Reaction yet to be attempted238U 55Mn 293Uus Reaction yet to be attempted

237Np 54Cr 291Uus Reaction yet to be attempted244Pu 51V 295Uus Reaction yet to be attempted243Am 50Ti 293Uus Reaction yet to be attempted248Cm 45Sc 293Uus Reaction yet to be attempted250Cm 45Sc 295Uus Reaction yet to be attempted249Bk 48Ca 297Uus Successful reaction249Cf 41K 290Uus Reaction yet to be attempted252Cf 41K 293Uus Reaction yet to be attempted253Es 40Ar 293Uus Reaction yet to be attempted

Hot fusion

249Bk (48Ca, xn)297-xUus (x=3,4)

Between July 2009 and February 2010, the team at the JINR (Flerov Laboratory of Nuclear Reactions) ran a7-month-long experiment to synthesize ununseptium using the reaction above.[2] The expected cross-sectionwas of the order of 2 pb. The expected evaporation residues, 293Uus and 294Uus, were predicted to decay viarelatively long decay chains as far as isotopes of dubnium or lawrencium.


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Calculated decay chains from the parent nuclei 293Uusand 294 Uus[3]

Calculated excitation function for the production of thecompound nucleus 297Uus from the reaction249Bk(48Ca,xn) [3]

The team published a scientific paper in April 2010 (first results were presented in January 2010[4]) that sixatoms of the neighbouring isotopes 294Uus (one atom) and 293Uus (five atoms) were detected. The heavierisotope decayed by the successive emission of six alpha particles down as far as the new isotope 270Db which


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underwent apparent spontaneous fission. On the other hand, the lighter odd-even isotope decayed by theemission of just three alpha particles, as far as 281Rg, which underwent spontaneous fission. The reaction wasrun at two different excitation energies of 35 MeV (dose 2x1019) and 39 MeV (dose 2.4×1019). Initial decaydata was published as a preliminary presentation on the JINR website.[5]

A further experiment in May 2010, looking at the chemistry of one of the decay products, ununtrium, identifieda further two atoms derived from 294Uus.

Chronology of isotope discovery

Isotope Year discovered Discovery reaction294Uus 2009 249Bk(48Ca,3n)293Uus 2009 249Bk(48Ca,4n)

Theoretical calculations

Evaporation residue cross sections

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

DNS = Di-nuclear system; σ = cross section

Target Projectile CN Channel (product) σmax Model Ref209Bi 82Se 291Uus 1n (290Uus) 15 fb DNS [6]

209Bi 79Se 288Uus 1n (287Uus) 0.2 pb DNS [6]

232Th 59Co 291Uus 2n (289Uus) 0.1 pb DNS [6]

238U 55Mn 293Uus 2-3n (291,290Uus) 70 fb DNS [6]

244Pu 51V 295Uus 3n (292Uus) 0.6 pb DNS [6]

248Cm 45Sc 293Uus 4n (289Uus) 2.9 pb DNS [6]

246Cm 45Sc 291Uus 4n (287Uus) 1 pb DNS [6]

249Bk 48Ca 297Uus 3n (294Uus) 2.1 pb ; 3 pb DNS [6][7]

247Bk 48Ca 295Uus 3n (292Uus) 0.8, 0.9 pb DNS [6][7]

Decay characteristics

Theoretical calculations in a quantum tunneling model with mass estimates from a macroscopic-microscopicmodel predict the alpha-decay half-lives of isotopes of ununseptium (namely, 289–303Uus) to be around 0.1–40ms.[8][9][10]


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^ a b Yu. Ts. Oganessian et al., Synthesis of a New Element with Atomic Number Z=117 (http://prl.aps.org/abstract/PRL/v104/i14/e142502), Phys. Rev. Lett. 104, 142502 (2010). doi:10.1103/PhysRevLett.104.142502(http://dx.doi.org/10.1103%2FPhysRevLett.104.142502) PMID 20481935.

1.

^ Ununseptium – the 117th element (http://www.atominfo.ru/en/news/e0298.htm) at AtomInfo.ru2.^ a b Roman Sagaidak. "Experiment setting on synthesis of superheavy nuclei in fusion-evaporation reactions.Preparation to synthesis of new element with Z=117" (http://159.93.28.88/linkc/education/SHE_Sagaidak.pdf).Retrieved 2009-07-07.

3.

^ Recommendations: 31st meeting, PAC for Nuclear Physics (http://www.jinr.ru/img_sections/PAC/NP/31/PAK_NP_31_recom_eng.pdf)

4.

^ Walter Grenier: Recommendations (http://ftp.jinr.ru/SC107/Presentations/Greiner.ppt), a PowerPoint presentationat the January 2010 meeting of the PAC for Nuclear Physics

5.

^ a b c d e f g h i 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 (//arxiv.org/abs/0708.0159). Bibcode:2007ChPhL..24.2551F (http://adsabs.harvard.edu/abs/2007ChPhL..24.2551F). doi:10.1088/0256-307X/24/9/024 (http://dx.doi.org/10.1088%2F0256-307X%2F24%2F9%2F024).

6.

^ a b Feng, Z; Jin, G; Li, J; Scheid, W (2009). "Production of heavy and superheavy nuclei in massive fusionreactions". Nuclear Physics A 816: 33. arXiv:0803.1117 (//arxiv.org/abs/0803.1117).Bibcode:2009NuPhA.816...33F (http://adsabs.harvard.edu/abs/2009NuPhA.816...33F).doi:10.1016/j.nuclphysa.2008.11.003 (http://dx.doi.org/10.1016%2Fj.nuclphysa.2008.11.003).

7.

^ C. Samanta, P. Roy Chowdhury and D.N. Basu (2007). "Predictions of alpha decay half lives of heavy andsuperheavy elements". Nucl. Phys. A 789: 142. arXiv:nucl-th/0703086 (//arxiv.org/abs/nucl-th/0703086).Bibcode:2007NuPhA.789..142S (http://adsabs.harvard.edu/abs/2007NuPhA.789..142S).doi:10.1016/j.nuclphysa.2007.04.001 (http://dx.doi.org/10.1016%2Fj.nuclphysa.2007.04.001).

8.

^ P. Roy Chowdhury, C. Samanta, and D. N. Basu (2008). "Search for long lived heaviest nuclei beyond the valleyof stability". Phys. Rev. C 77 (4): 044603. arXiv:0802.3837 (//arxiv.org/abs/0802.3837).Bibcode:2008PhRvC..77d4603C (http://adsabs.harvard.edu/abs/2008PhRvC..77d4603C).doi:10.1103/PhysRevC.77.044603 (http://dx.doi.org/10.1103%2FPhysRevC.77.044603).

9.

^ P. Roy Chowdhury, C. Samanta, and D. N. Basu (2008). "Nuclear half-lives for α -radioactivity of elements with100 ≤ Z ≤ 130". At. Data & Nucl. Data Tables 94 (6): 781–806. arXiv:0802.4161 (//arxiv.org/abs/0802.4161).Bibcode:2008ADNDT..94..781C (http://adsabs.harvard.edu/abs/2008ADNDT..94..781C).doi:10.1016/j.adt.2008.01.003 (http://dx.doi.org/10.1016%2Fj.adt.2008.01.003).

10.

Isotope masses from:M. Wang, G. Audi, A.H. Wapstra, F.G. Kondev, M. MacCormick, X. Xu, et al. (2012). "TheAME2012 atomic mass evaluation (II). Tables, graphs and references." (http://amdc.in2p3.fr/masstables/Ame2012/Ame2012b-v2.pdf). Chinese Physics C, 36 (12): 1603–2014.Bibcode:2012ChPhC..36....3M (http://adsabs.harvard.edu/abs/2012ChPhC..36....3M).doi:10.1088/1674-1137/36/12/003 (http://dx.doi.org/10.1088%2F1674-1137%2F36%2F12%2F003).Ame2003 Atomic Mass Evaluation (http://www.nndc.bnl.gov/amdc/index.html): G. Audi, O.Bersillon, J. Blachot, A.H. Wapstra, The Nubase evaluation of nuclear and decay properties, Nucl.Phys. A729 (2003) 3-128.

Isotopic compositions and standard atomic masses from Atomic Weights of the Elements: Review 2000(IUPAC Technical Report) (http://www.iupac.org/publications/pac/2003/pdf/7506x0683.pdf). Pure Appl.Chem., Vol. 75, No. 6, pp. 683–800, (2003).


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Isotopes of livermorium Isotopes of ununseptium Isotopes ofununoctium

Table of nuclides

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