ADOPTED LEVELS, GAMMAS for 76Co

Authors: Balraj Singh, Jun Chen and Ameenah R. Farhan |  Citation: Nucl. Data Sheets 194, 3 (2024) |  Cutoff date: 8-Jan-2024 

 Full ENSDF file | Adopted Levels (PDF version) 


Q(β-)=16530 keV SYS(n)= 3170 keV SYS(p)= 18250 keV SYQ(α)= -16920 keV SY
Reference: 2021WA16

References:
  A  76Co IT decay (2.96 μs) 

General Comments:

2010Oh02: 76Co nuclide identified in Be(238U,F) and Pb(238U,F) reactions with a 238U86+ beam energy of 345 MeV/nucleon produced by the cascade operation of the RBIF accelerator complex of the linear accelerator RILAC and four cyclotrons RRC, fRC, IRC and SRC. Identification of 76Co nuclei was made on the basis of magnetic rigidity, time-of-flight and energy loss of the fragments using BigRIPS fragment separator. Experiments performed at RIKEN facility. Based on α/Q spectrum and Z versus α/Q plot, 5 counts were assigned to 76Co isotope. (Q=charge state)

2014Xu07 (also 2014XuZZ thesis): same reaction and experimental arrangement used to produce 76Co as in 2010Oh02 at RIBF-RIKEN facility. Measured heavy fragment, β and γ spectra using wide-range active silicon strip stopper array (WAS3ABi) for β and ion detection, and EUROBALL-RIKEN Cluster array for γ detection. Decay curves were obtained from time differences between implantation and correlated β decays. See also 2014XuZZ thesis

2015So23: 76Co isomers produced in 9Be(238U,F), E=345 MeV/nucleon reaction with the 238U beam provided by the RIBF accelerator complex at RIKEN facility. Fission fragments were separated and analyzed by BigRIPS separator, transported to focal plane of ZeroDegree spectrometer. Particle identification was achieved by ΔE-tof-Bρ method. Silicon detector stack WAS3ABi was used for ion implantation and β detection. Gamma rays were detected using EURICA array of 12 HPGe cluster detectors arranged in three rings at 51|’, 90|’ and 120|’ with respect to the beam direction. About 1000 76Co ions were implanted in the WAS3ABi Si detector stack. Measured Eγ, Iγ, γγ-coin, βγ(t), half-lives of isomers in 76Co and 76Ni. Deduced isomers, levels, J, π, configurations. Shell-model calculation with LNPS interaction for structure of 76Co

Theoretical calculations: two primary references for structure and two for decay characteristics retrieved from the NSR database (www.nndc.bnl.gov/nsr/) are listed in this dataset under ’document’ records.

Q-value: Estimated uncertainties (2021Wa16): 580 for Q(β-), 640 for S(n), 780 for S(p) and Q(α)

Q-value: S(2n)=8260 640, Q(β-n)=10510 540 (syst,2021Wa16). S(2p)=39540 (2019Mo01,theory). Q(β-2n)=6900 540, Q(β-3n)=235 500 (syst) deduced by evaluators from mass values in 2021Wa16










E(level)
(keV)		XREFJπ(level) T1/2(level)E(γ)
(keV)		I(γ)M(γ)Final Levels
    0.0A (1-) 16 ms 4 
% β- = 100
% β-n = ?
% β-2n = ?
     
  0+X  (8-) 21.7 ms +65-49 
% β-n = ?
% β-2n = ?
% β- ≈ 100
     
  446.4 7 A (2-)     446.4 7 
  100

    0.0
(1-)
  638.4 8 A (3+) 2.96 µs +29-25 
% IT ≈ 100
  192.02 30 
  100
[E1]
  446.4
(2-)

Jπ(level): As given in Fig. 4 of 2015So23, based on shell-model calculations

E(γ): From 76Co IT decay (2015So23)

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Additional Gamma Data:













E(level)
(keV)		Jπ(level)T1/2(level)E(γ)
(keV)		MultipolarityConversion
Coefficient		Additional Data
  638.4 (3+) 2.96 µs +29-25 
% IT ≈ 100
  192.02 30 [E1]0.0064B(E1)(W.u.)=1.79E-8 16, α=0.0064

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Additional Level Data and Comments:

E(level)Jπ(level)T1/2(level)Comments
    0.0(1-) 16 ms 4 
% β- = 100
% β-n = ?
% β-2n = ?
Theoretical T1/2=12.7 ms, %β-n=18, %β-2n=2 (2019Mo01).
E(level): Theoretical T1/2=12.7 ms, %β-n=18, %β-2n=2 (2019Mo01).
Jπ(level): Possible member of πf7/2-1~#νg9/2-1 multiplet.
  0+X(8-) 21.7 ms +65-49 
% β-n = ?
% β-2n = ?
% β- ≈ 100
Since no events were observed for neighboring hydrogen-like peaks, the misidentification of 76Co is not likely (2010Oh02).
Jπ(level): Possible member of πf7/2-1~#νg9/2-1 multiplet.
  446.4(2-)   Jπ(level): Possible member of πf7/2-1~#νg9/2-1 multiplet.
  638.4(3+) 2.96 µs +29-25 
% IT ≈ 100
This isomer decays to g.s. by 446.4γ-192.02γ cascade with a level sequence of (3+) -> (2-) -> (1-).

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Additional Gamma Comments:

E(level)E(gamma)Comments
  638.4  192.02M(γ): proposed by 2015So23 as E1 based on comparison of the measured half-life with expected half-lives for different mutipolarities of 192 and 446 γ rays: M1, E2, E3 for intraband transitions with assumed 1 W.u. transition probability; E1, M2, E3 for interband transitions with theoretical transition probabilities from shell-model calculations.

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