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

 Full ENSDF file | Adopted Levels (PDF version) 

Q(β-)=-3030 keV SYS(n)= 6380 keV SYS(p)= 1980 keV SYQ(α)= 9220 keV 40
Reference: 2017WA10

  A  270Mt α decay (0.48 S) 

General Comments:

Edited by B. Singh, June 24, 2020: comment for half-life from 2000Wi15 modified. 1997Mo25 reference updated to 2019Mo01. No new experimental references since the 2019 update.

2000Wi15: chemical investigation aimed at the study of 266,267Bh. Reaction: 249Bk(22Ne,5n) at the 88-inch cyclotron of LBNL which provided the 22Ne(6+) beam at energies of 148 and 153 MeV corresponding to 116-118 MeV and 122-124 MeV respectively in the target. The target was 0.81 mg/cm2 249Bk as oxide prepared by the molecular plating technique. Chemical separation prior to this ensured that less than 0.5% of 249Cf was present. Reaction products collected in a recoil chamber located directly behind the target. This chamber was continuously swept with He gas containing KCl aerosols to collect the products. The products were then guided through a TEFLON capillary (1.4 mm, 7 min in length) to the merry-go-round (Mg) rotating wheel system. One decay chain of 266Bh was observed at the higher beam energy of 122-124 MeV followed by an α-decay sequence. The cross-section estimated for the 5n-reaction channel was 25-250 pb, based on an expected unhindered half-life of T1/2≈0.5 s for this nuclide with Q(α)=9.29 MeV. Due to the experimental set-up, this cross-section was strongly dependent on the assumed 267Bh half-life. The estimated half-life for 266Bh was T1/2≈1-10 s; suggested value is within 1 s. Fission decay properties of 266Bh and 267Bh could not be determined due to contamination from 256Fm SF decay.

Event #1:

Eα1=9290 keV, t1=0.87 s, assigned to 266Bh

Eα2=8540 keV, t2=27.83 s, assigned to 262Db

Eα3=8740 keV, t3=0.04 s, assigned to 258Lr

2004Mo42, 2007Mo43, 2012Mo25: 266Bh produced as α-great-granddaughter of 278Nh, which was formed in 209Bi(70Zn,n) E=349 MeV reaction at RIKEN. See 278Nh Adopted Levels for details of three correlated decay chains observed. Results are summarized by 2015Mo25.

2006Qi03: 266Bh produced directly in 243Am(26Mg,3n),E=162 MeV reaction (126 MeV at mid target) at HIRFL, Lanzhou facility. Total of four α-α-α correlated decay chains were observed. Deduced average Eα, T1/2 of 266Bh decay and production σ.

History of decay chains in 2006Qi03:

Event #1:

Eα1=8989 keV, t1=1.13 s, assigned to 266Bh

Eα2=8459 keV, t2=33.52 s, assigned to 262Db

Event #2:

Eα1=9071 keV, t1=0.79 s, assigned to 266Bh

Eα2=8604 keV, t2=34.14 s, assigned to 262Db

Event #3:

Eα1=8959 keV, t1=0.51 s, assigned to 266Bh

Eα2=8542 keV, t2=29.23 s, assigned to 262Db

Eα3=8641 keV, t3=5.07 s, assigned to 258Lr

Event #4:

Eα1=9106 keV, t1=1.52 s, assigned to 266Bh

Eα2=8518 keV, t2=53.09 s, assigned to 262Db

Other: 1987ScZR

For theoretical studies, consult Nuclear Science References (NSR) database at NNDC, BNL for 42 primary references dealing with the half-lives and other aspects of nuclear structure in this mass region

Q-value: Estimated uncertainties (2017Wa10): ΔQ(β-)=170, ΔS(n)=290, ΔS(p)=200, ΔQ(α)=80

Q-value: Q(α) from Eα=9.08 MeV 4 (2004Mo42). Others: 9.43 MeV from Eα=9.29 MeV (2000Wi15), 9430 80 (syst, 2017Wa10)

Q-value: S(2n)=14100 240, S(2p)=5840 290 (syst, 2017Wa10).

XREF T1/2(level)
  0A 2.1 s +29-8 
% SF = ?
% α ≈ 100

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Additional Level Data and Comments:

  0 2.1 s +29-8 
% SF = ?
% α ≈ 100
Eα=9.08 MeV 4 (2004Mo42), 9.77 MeV 4 (2007Mo43), 9.39 MeV 6 (2012Mo25), 9.03 MeV 8 (2006Qi03), 9.29 MeV (2000Wi15) from α decay of 266Bh. Unweighted average of the first four values is 9.32 MeV 17 (evaluator).
E(level): Eα=9.08 MeV 4 (2004Mo42), 9.77 MeV 4 (2007Mo43), 9.39 MeV 6 (2012Mo25), 9.03 MeV 8 (2006Qi03), 9.29 MeV (2000Wi15) from α decay of 266Bh. Unweighted average of the first four values is 9.32 MeV 17 (evaluator).

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