Author: Balraj Singh |  Citation: Nucl. Data Sheets 141, 327 (2017) |  Cutoff date: 22-Mar-2017 

 Full ENSDF file | Adopted Levels (PDF version) 

S(n)= 7170 keV SYS(p)= 1120 keV SYQ(α)= 9340 keV 30
Reference: 2017WA10

  A  260Bh α decay (35 MS) 

General Comments:

Theoretical calculations: consult the Nuclear Science References (NSR) database for about 27 theory references.

1983OgZX: 256Db claimed to have been observed as an SF activity in 209Bi(49Ti,2n); measured half-life from SF and α-decay curves. According to results of experiments in 2001He35, the SF activity reported by 1983OgZX was most likely from 256Rf produced in ε decay of 256Db.

2001He35 (also 1999He11,1999He07): 256Db produced in 209Bi(50Ti,3n),E=4.59-5.08 MeV/nucleon, evaporation residues from filtering by SHIP separator at GSI. Measured Eα, T1/2(α), αα and α(SF) parent-daughter correlations. α total of 16 α-decay chains were assigned involving the production of 256Db. The authors also found evidence for ε decay mode of 256Db resulting in 256Rf which decays primarily by SF decay mode, and that is the SF activity which was most likely observed by 1983OgZX.

2008Ne01: 256Db from α decay of 260Bh produced in 209Bi(52Cr,n),E=257.0 MeV beam provided by 88-Inch Cyclotron at LBNL. The nuclei were analyzed using Berkeley Gas-Filled Separator. 256Db, 252Lr and 248Md formed through successive α-decay chain.

There are several α groups reported by 2008Ne01 in 260Bh α decay which suggests population of excited states in 256Db, but no levels have been explicitly proposed at present.

Q-value: Estimated uncertainties (2017Wa10): 430 for S(n), 270 for S(p)

Q-value: S(2n)=16140 (theory,1997M025). S(2p)=3950 390, Q(εp)=3260 240 (syst,2017Wa10)

XREF T1/2(level)
  0.0A 1.6 s +5-3 
% ε = 30 11
% α = 70 11
% SF = ?

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Additional Level Data and Comments:

  0.0 1.6 s +5-3 
% ε = 30 11
% α = 70 11
% SF = ?
Theoretical half-lives (1997Mo25) of 15.1 s for α and 22.9 s for β decays, for example predict %α=17.2 and %β+=11.4 which suggest %SF=71.4. Theoretical calculations by 1985Lo17 predict T1/2(SF)≈0.01 s, suggesting %SF≈100, which is in disagreement with experimental results from 2008Ne01 and 2001He35, who determined large α and β branches, and no evidence of SF decay.

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