ADOPTED LEVELS, GAMMAS for 241Cm

Author: C.D. Nesaraja |  Citation: Nucl. Data Sheets 130, 183 (2015) |  Cutoff date: 30-Sep-2015 

 Full ENSDF file | Adopted Levels (PDF version) 


Q(β-)=-2330 keV SYS(n)= 6093.3 keV 21S(p)= 5097 keV 14Q(α)= 6185.2 keV 6
Reference: 2012WA38

References:
  A  245Cf α decay  B  241Bk ε decay






E(level)
(keV)
XREFJπ(level) T1/2(level)E(γ)
(keV)
Final Levels
      0.0AB 1/2+ 32.8 d 2 
% ε = 99.0 1
% α = 1.0 1
   
      5.5AB (3/2+)      
     57.1AB (5/2+)     51.6
  57.1
      5.5
      0.0
(3/2+)
1/2+
     81?A  (7/2+)      
    163?A  (9/2+)      
    267.8 B (5/2+)      
    420.2 B (7/2+)      
  ≈2300   15.3 ns 10 
% SF = 100
   

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Band Transitions:

E(level)
(keV)
Jπ(level) T1/2(level)E(γ)Final Levels
Band 1 - 1/2+[631] band
      0.0 1/2+ 32.8 d 2 
% ε = 99.0 1
% α = 1.0 1
   
      5.5 (3/2+)      
     57.1 (5/2+)     51.6
  57.1
      5.5
      0.0
(3/2+)
1/2+

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Additional Level Data and Comments:

E(level)Jπ(level)T1/2(level)Comments
      0.01/2+ 32.8 d 2 
% ε = 99.0 1
% α = 1.0 1
E(level): 1/2+[631] band.
      5.5(3/2+)   E(level): 1/2+[631] band.
Jπ(level): The following arguments are based on those given by 1996Ma72 in their 245Cf α decay paper. On the basis of the observation of 56.1 and 50.6 gammas in coincidence with the 7083α, and the absence of any gammas in coincidence with the 7138α, the authors propose the existence of excited levels at 5.6 and 56.1. From systematics, the g.s. configuration for 245Cf is expected to be 5/2[622] or 1/2[631]. HF(7138α)<4 identifies the 7138α as the favored transition connecting states of the same configuration, and HF(7083α)=20 suggests that the 7083α and 7138α feed members of the same band. If the configuration of 245Cf is 5/2[622], then the 7138 and 7083 α’s must feed the 5/2+ and 7/2+ members of this band in the daughter 245Cm; however, the deduced rotational parameters do not agree with systematics for this configuration. The evaluator notes that these systematics lead to an expected 7/2 - 5/2 separation of 44 keV rather than 56 keV. On the other hand, if the parent configuration is 1/2[631], then the 7138 α feeds the g.s., and the assumption that the 5.6 and 56.1 levels are the 3/2+ and 5/2+ members of this band gives rotational parameters consistent with systematics for the 1/2[631] band. The evaluator adopts these assignments.
     57.1(5/2+)   E(level): 1/2+[631] band.
Jπ(level): The following arguments are based on those given by 1996Ma72 in their 245Cf α decay paper. On the basis of the observation of 56.1 and 50.6 gammas in coincidence with the 7083α, and the absence of any gammas in coincidence with the 7138α, the authors propose the existence of excited levels at 5.6 and 56.1. From systematics, the g.s. configuration for 245Cf is expected to be 5/2[622] or 1/2[631]. HF(7138α)<4 identifies the 7138α as the favored transition connecting states of the same configuration, and HF(7083α)=20 suggests that the 7083α and 7138α feed members of the same band. If the configuration of 245Cf is 5/2[622], then the 7138 and 7083 α’s must feed the 5/2+ and 7/2+ members of this band in the daughter 245Cm; however, the deduced rotational parameters do not agree with systematics for this configuration. The evaluator notes that these systematics lead to an expected 7/2 - 5/2 separation of 44 keV rather than 56 keV. On the other hand, if the parent configuration is 1/2[631], then the 7138 α feeds the g.s., and the assumption that the 5.6 and 56.1 levels are the 3/2+ and 5/2+ members of this band gives rotational parameters consistent with systematics for the 1/2[631] band. The evaluator adopts these assignments.
    267.8(5/2+)   Configuration=5/2+[622] (2003As01).
Jπ(level): 2003As01 suggest that the ε decay proceeds from the parent 7/2[633] state to the 7/2[624] state in 241Cm, expected to lie at ≈420 keV. They point out that the inverse transition in 243Pu β- decay has log ft=5.5, and the similar transitions from 5/2[642] to 5/2[633] in 232Np, 233Np, 235Pu, and 236Am ε decays have log ft values in the range 4.8 to 5.4. For the 420 level, a log ft of 5.0 to 5.5 lead to a deduced T1/2(241Bk) of 4.4 to 14 minutes, consistent with the measured T1/2. The authors further suggest that the three transitions they observe in ε decay can be assigned as decay from the 7/2[624] level to the 5/2[622] band head, followed by transitions to the 3/2 and 5/2 members of the 1/2[631] g.s. band. The energy of the 3/2+ member of the 1/2[631] has been determined in 245Cf α decay.
    420.2(7/2+)   Configuration=7/2+[624] (2003As01).
Jπ(level): 2003As01 suggest that the ε decay proceeds from the parent 7/2[633] state to the 7/2[624] state in 241Cm, expected to lie at ≈420 keV. They point out that the inverse transition in 243Pu β- decay has log ft=5.5, and the similar transitions from 5/2[642] to 5/2[633] in 232Np, 233Np, 235Pu, and 236Am ε decays have log ft values in the range 4.8 to 5.4. For the 420 level, a log ft of 5.0 to 5.5 lead to a deduced T1/2(241Bk) of 4.4 to 14 minutes, consistent with the measured T1/2. The authors further suggest that the three transitions they observe in ε decay can be assigned as decay from the 7/2[624] level to the 5/2[622] band head, followed by transitions to the 3/2 and 5/2 members of the 1/2[631] g.s. band. The energy of the 3/2+ member of the 1/2[631] has been determined in 245Cf α decay.
   2300 15.3 ns 10 
% SF = 100
For theoretical calculations of T1/2(SF) see, for example, 1978Po09, 1985Lo17, and 1990Bh02.
E(level): For theoretical calculations of T1/2(SF) see, for example, 1978Po09, 1985Lo17, and 1990Bh02.

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Additional Gamma Comments:

E(level)E(gamma)Comments
     57.1     51.6E(γ): From Eγ(262.3 1)-(210.7 2) from the 268 level in ε decay E=50.6 is reported in α decay
     57.1E(γ): From Eγ(262.3 1) from the 268 level in ε decay and E(5.5 level) from α decay. E=56.1 is reported in α decay

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