Isotopes of ununpentium

Ununpentium (Uup) is a synthetic element, and thus a standard atomic mass cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was ²⁸⁸Uup in 2004. There are four known radioisotopes from ²⁸⁷Uup to ²⁹⁰Uup.

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)	daughter isotope(s)	nuclear spin
^287Uup	115	172	287.19070(52)#	32(+155−14) ms	α	^283Uut
^288Uup	115	173	288.19274(62)#	87(+105−30) ms	α	^284Uut
^289Uup[n 1]	115	174	289.19363(89)#	220 ms[1]	α	^285Uut
^290Uup[n 2]	115	175	290.19598(73)#	16 ms[1]	α	^286Uut

1. Not directly synthesized, created as decay product of ²⁹³Uus
2. Not directly synthesized, created as decay product of ²⁹⁴Uus

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.

Nucleosynthesis

Chronology of isotope discovery

Isotope	Year discovered	Discovery reaction
^287Uup	2003	^243Am(^48Ca,4n)
^288Uup	2003	^243Am(^48Ca,3n)
^289Uup	2009	^249Bk(^48Ca,4n)[1]
^290Uup	2009	^249Bk(^48Ca,3n)[1]

Target-projectile combinations

The table below contains various combinations of targets and projectiles which could be used to form compound nuclei with Z=115. Each entry is acombination for which calculations have provided estimates for cross section yields from various neutron evaporation channels. The channel with the highest expected yield is given.

Target	Projectile	CN	Attempt result
^208Pb	^75As	^283Uup	Reaction yet to be attempted
^232Th	^55Mn	^287Uup	Reaction yet to be attempted
^238U	^51V	^289Uup	Failure to date
^237Np	^50Ti	^287Uup	Reaction yet to be attempted
^244Pu	^45Sc	^289Uup	Reaction yet to be attempted
^243Am	^48Ca	^291Uup[2][3]	Successful reaction
^241Am	^48Ca	^289Uup	Planned Reaction
^248Cm	^41K	^289Uup	Reaction yet to be attempted
^249Bk	^40Ar	^289Uup	Reaction yet to be attempted
^249Cf	^37Cl	^286Uup	Reaction yet to be attempted

Hot fusion

Hot fusion reactions are processes that 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(⁵¹V,xn)^289−xUup

There are strong indications that this reaction was performed in late 2004 as part of a uranium(IV) fluoride target test at the GSI. No reports have been published suggesting that no products atoms were detected, as anticipated by the team.^[4]

²⁴³Am(⁴⁸Ca,xn)^291−xUup (x=2,3,4)

This reaction was first performed by the team in Dubna in July–August 2003. In two separate runs they were able to detect 3 atoms of ²⁸⁸Uup and a single atom of ²⁸⁷Uup. The reaction was studied further in June 2004 in an attempt to isolate the descendant ²⁶⁸Db from the ²⁸⁸Uup decay chain. After chemical separation of a +4/+5 fraction, 15 SF decays were measured with a lifetime consistent with ²⁶⁸Db. In order to prove that the decays were from dubnium-268, the team repeated the reaction in August 2005 and separated the +4 and +5 fractions and further separated the +5 fractions into tantalum-like and niobium-like ones. Five SF activities were observed, all occurring in the +5 fractions and none in the tantalum-like fractions, proving that the product was indeed isotopes of dubnium.

In a series of experiments between October 2010 – February 2011, scientists at the FLNR studied this reaction at a range of excitation energies. They were able to detect 21 atoms of ²⁸⁸115 and one atom of ²⁸⁹115, from the 2n exit channel. This latter result was used to support the synthesis of ununseptium. The 3n excitation function was completed with a maximum at ~8 pb. The data was consistent with that found in the first experiments in 2003.

Reaction yields

The table below provides cross-sections and excitation energies for hot fusion reactions producing ununpentium 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	^243Am	^291Uup		3.7 pb, 39.0 MeV	0.9 pb, 44.4 MeV

Theoretical calculations

Decay characteristics

Theoretical calculations using a quantum-tunneling model support the experimental alpha-decay half-lives.^[5]

Evaporation residue cross sections

The table below contains various target-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.

MD = multi-dimensional; DNS = Di-nuclear system; σ = cross section

Target	Projectile	CN	Channel (product)	σmax	Model	Ref
^243Am	^48Ca	^291Uup	3n (^288Uup)	3 pb	MD	[2]
^243Am	^48Ca	^291Uup	4n (^287Uup)	2 pb	MD	[2]
^243Am	^48Ca	^291Uup	3n (^288Uup)	1 pb	DNS	[3]
^242Am	^48Ca	^290Uup	3n (^287Uup)	2.5 pb	DNS	[3]

References

1. Oganessian, Yuri Ts.; Abdullin, F. Sh.; Bailey, P. D.; et al. (2010-04-09). "Synthesis of a New Element with Atomic Number Z=117". Physical Review Letters (American Physical Society) 104 (142502): 142502. Bibcode:2010PhRvL.104n2502O. doi:10.1103/PhysRevLett.104.142502. PMID 20481935.
2. Zagrebaev, V. (2004). "Fusion-fission dynamics of super-heavy element formation and decay" (PDF). Nuclear Physics A 734: 164–167. Bibcode:2004NuPhA.734..164Z. doi:10.1016/j.nuclphysa.2004.01.025.
3. Feng, Z; Jin, G; Li, J; Scheid, W (2009). "Production of heavy and superheavy nuclei in massive fusion reactions". Nuclear Physics A 816: 33–51. arXiv:0803.1117. Bibcode:2009NuPhA.816...33F. doi:10.1016/j.nuclphysa.2008.11.003.
4. "List of experiments 2000–2006". Univerzita Komenského v Bratislave. Archived from the original on July 23, 2007.
5. C. Samanta; P. Roy Chowdhury; 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.

• Isotope masses from:
  • M. Wang; G. Audi; A. H. Wapstra; F. G. Kondev; M. MacCormick; X. Xu; et al. (2012). "The AME2012 atomic mass evaluation (II). Tables, graphs and references." (PDF). Chinese Physics C 36 (12): 1603–2014. Bibcode:2012ChPhC..36....3M. doi:10.1088/1674-1137/36/12/003.
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.
• Isotopic compositions and standard atomic masses from:
  • J. R. de Laeter; J. K. Böhlke; P. De Bièvre; H. Hidaka; H. S. Peiser; K. J. R. Rosman; P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry 75 (6): 683–800. doi:10.1351/pac200375060683.
  • M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry 78 (11): 2051–2066. doi:10.1351/pac200678112051. Lay summary.
• Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005.
  • N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0-8493-0485-9.