Author: Balraj Singh |  Citation: Nucl. Data Sheets 156, 70 (2019) |  Cutoff date: 31-Jan-2019 

 Full ENSDF file | Adopted Levels (PDF version) 

Q(β-)=-4490 keV SYS(n)= 7250 keV SYS(p)= 4150 keV SYQ(α)= 8800 keV SY
Reference: 2017WA10

  A  270Hs α decay (7.6 S) 

General Comments:

2006Dv01, 2008Dv02: 266Sg produced as α-daughter of 270Hs, which was formed in 248Cm(26Mg,4n),E=193,185 MeV reaction at GSI, and assignment to the isotope made through the observation of four correlated (α-SF) decay chains in 2006Dv01, and two in 2008Dv02 which were attributed to 270Hs on the basis of α-SF correlations. These studies negated the discovery of 266Sg, published in several articles (2003Tu05, 2003Du27, 2002Du21, 2001Hu22, 1998Tu01, 1997Sc48, 1997Sc49 from the GSI group; and 1995Og02, 1994La22, 1994Lo27, 1994La22, 1994Og04 from the Dubna-LLNL group), and assigned the events in these earlier studies to 269Hs decaying by α decay to 265Sg, which also decays partially by α. See 270Hs Adopted Levels for history of six correlated decay chains observed in the above two works.

2013Og03: 266Sg produced as α-daughter of 270Hs isotope, which was formed in 226Ra(48Ca,4n) reaction E(48Ca)=229, 234, 241 MeV at Dubna. This study confirmed conclusions of the GSI experiments by 2006Dv01 and 2008Dv02. See 270Hs Adopted Levels for history of six correlated decay chains observed by 2013Og03.

Earlier studies where either direct production of 266Sg or through the α decay of 270Hs was claimed in the first experiments at Dubna, and later at GSI, but later these activities were reassigned to 265Sg or 269Hs by 2006Dv01 and 2008Dv02 at GSI, and confirmed in 2013Og03 at Dubna. The following studies are listed here only from the historical perspective of search for 266Sg during 1994-2004 at Dubna and GSI.

1994La22 (also 1994Lo27, 1994Og04, 1995Og02): 248Cm(22Ne,4n), E=116,121 MeV at Dubna. Six α-SF correlated events were reported. The α-decay half-life of 266Sg was suggested as 10-30 s, with α decay as the primary mode (%α|>50), Eα=8.63 MeV 5.

1997Sc48, 1997Sc49, 1998Tu01: 248Cm(22Ne,4n),E=121 MeV at GSI using UNILAC accelerator and On-Line Gas chemistry Apparatus (OLGA). Four α-SF decay chains were assigned to the decay of 266Sg. The α-decay half-life of 266Sg was reported as 21 s +20-12, with Eα=8.77 MeV 4, and the decay of 266Sg through α and SF modes.

2001Hu22: chemistry-related experiments at GSI using the same reaction as in 1998Tu01. Two decay chains reported with α-decay half-life of 21.1 s and Eα=8.66 and 8.70 MeV.

2002Du21, 2003Du27, 2003Tu05 (also 2003Kr24 review): two α-α-SF correlated decay chains (270Hs |) 266Sg |) 262Rf) were reported using the 248Cm(26Mg,4n),E=143.7-146.8 MeV reaction and chemistry techniques at GSI.

2004Vo24: this experiment reports mainly the chemistry of Z=108 (Hs) element through the formation of 269Hs or 270Hs in 248Cm(26Mg,4n) at GSI. Three α-α-SF correlated events were assigned to the decay of 269Hs or 270Hs.

For theoretical studies, consult Nuclear Science References (NSR) database at NNDC, BNL for 105 primary references dealing with the half-lives and other aspects of nuclear structure in this mass region

Q-value: Estimated uncertainties (2017Wa10): ΔQ(β-)=290, ΔS(n)=270, ΔS(p)=330, ΔQ(α)=100

Q-value: S(2n)=13310 370, S(2p)=7040 440 (syst, 2017Wa10).

XREFJπ(level) T1/2(level)
  0A 0+ 0.34 s +19-9 
% SF = 100

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Additional Level Data and Comments:

  00+ 0.34 s +19-9 
% SF = 100
Only the SF decay mode observed by 2013Og03 (Dubna group), 2008Dv02 and 2006Dv01 (GSI group). See comment for T1/2.

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