ADOPTED LEVELS for 231Np

Authors: Balraj Singh, Jagdish K. Tuli, and Edgardo Browne |  Citation: Nucl. Data Sheets 185, 560 (2022) |  Cutoff date: 31-Aug-2022 

 Full ENSDF file | Adopted Levels (PDF version) 


Q(β-)=-2680 keV 60S(n)= 7680 keV 80S(p)= 3280 keV 50Q(α)= 6370 keV 50
Reference: 2021WA16

References:
  A  235Am α decay (10.3 M) 

General Comments:

1950Ma14: 231Np produced and identified in 235U(d,6n),E=45-100 MeV at Berkeley, followed by chemical separation. From observation of α spectra from 231Np decay, parent-daughter correlation of 231Np and 227Pa was established. Measured half-life of the decay of 231Np

1973We08: 231Np produced in 233U(d,4n). Measured Eγ, Iγ, half-life of the decay of 231Np

Theoretical calculations: consult the NSR database (www.nndc.bnl.gov/nsr/) for 23 primary references for the decay characteristics of 231Np, and two for nuclear structure. These references are listed in ’document’ records, which can be accessed through on-line ENSDF database at www.nndc.bnl.gov/ensdf/

Q-value: S(2n)=14320 110, S(2p)=8850 50, Q(ε)=1820 50 (2021Wa16)






E(level)
(keV)
XREFJπ(level) T1/2(level)
  0A (5/2-) 48.8 m 2 
% ε ≈ 98
% α ≈ 2

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Additional Level Data and Comments:

E(level)Jπ(level)T1/2(level)Comments
  0(5/2-) 48.8 m 2 
% ε ≈ 98
% α ≈ 2
%α=2.0 if α to g.s. of 227Pa is favored. Measurements of 1950Ma14 established the α-decay mode, but only %ε/%α<100 (implying %α>1%) could be determined in their experiment. Systematics suggest %α<10. Theoretical calculations of T1/2(β)>100 s and T1/2(α)=7.4×105s (2019Mo01) suggest dominant ε+β+ decay mode.
E(level): %α=2.0 if α to g.s. of 227Pa is favored. Measurements of 1950Ma14 established the α-decay mode, but only %ε/%α<100 (implying %α>1%) could be determined in their experiment. Systematics suggest %α<10. Theoretical calculations of T1/2(β)>100 s and T1/2(α)=7.4×105s (2019Mo01) suggest dominant ε+β+ decay mode.

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