ADOPTED LEVELS, GAMMAS for 250Bk

Author: Y. Akovali |  Citation: Nucl. Data Sheets 94,131 (2001) |  Cutoff date: 1-Aug-2001 

 Full ENSDF file | Adopted Levels (PDF version) 


Q(β-)=1780 keV 4S(n)= 4970 keV 4S(p)= 5089 keV 6Q(α)= 5531 keV SY
Reference: 2012WA38

References:
  A  254Es α decay (275.7 d)  B  254Es α decay (39.3 H)
  C  249Bk(n,γ):(TENTATIVE) 

General Comments:

Since the 39.9H 254Es α decay and 249Bk(n,γ) data presented in this evaluation are considered as preliminary, level schemes and predominant configuration assignments given here, which are based mostly on these data, should Be taken as tentative, particularly in view of some interpretations that are inconsistent with data.

Assuming the level scheme is correct, the inconsistencies noted here can Be explained by large admixtures of other configurations. See 275.7-d 254Es and 39.3H 254Es α decays and 249Bk(n,γ) data sections for additional remarks.

Theoretical studies:

Fission-barrier properties were calculated by 1977Pr10, 1980Ku14, 1984Oh09, 1984Ku05, 1984Ro23.

For discussions and calculations of Gallagher-Moszkovski splitting, and of odd- and even-spin states’ energy shifts (Newby shifts), see, for example, 1986Ho30, 1986Ho36, 1986So12, 1988Fr16, 1989HoZI, 1994No15.

Q-value: Note: Current evaluation has used the following Q record










E(level)
(keV)
XREFJπ(level) T1/2(level)E(γ)
(keV)
I(γ)M(γ)Final Levels
     0.0ABC 2- 3.212 h 5 
% β- = 100
     
    34.47ABC (3-)      34.47
 
(M1,E2)
     0.0
2-
    35.59ABC (4+) 29 µs 1      1.12S
   35.59
 
  100
[E1]
(M2)
    34.47
     0.0
(3-)
2-
    78.33ABC (5+)      42.74
 
(M1+E2)
    35.59
(4+)
    80.26  C (4-)      45.79
   80.26
 
 
(M1+E2)
(E2)
    34.47
     0.0
(3-)
2-
    86 2 A   (7+) 213 µs 8      8S
 
[E2]
    78.33
(5+)
    97.49A C (5-) 38 ns 5     61.91
 
(E1)
    35.59
(4+)
   103.83 BC (1-)     103.83
 
(M1)
     0.0
2-
   115.45 BC (3+)      79.86
 
(M1)
    35.59
(4+)
   125.01 BC (2-)      90.53
  125.01
  100 30 
   75 30 
(M1)
(M1)
    34.47
     0.0
(3-)
2-
   130.49ABC (6+)      52.16
   94.91
 
 
(M1+E2)
(E2)
    78.33
    35.59
(5+)
(4+)
   137.32ABC (5-)      57.06
  102.84
 
 
(M1)
(E2)
    80.26
    34.47
(4-)
(3-)
   146.43  C (2-)     111.96
  146.43
 
 
(M1)
(M1+E2)
    34.47
     0.0
(3-)
2-
   148.60  C (4+)      70.27
  113.01
 
 
(M1)
(M1)
    78.33
    35.59
(5+)
(4+)
   156 2 A   (8+)      70.4 2 
 
(M1+E2)
    86
(7+)
   157.39  C (3-)      53.59
   77.13
  122.95
 
 
 
(E2)
(M1)
(M1)
   103.83
    80.26
    34.47
(1-)
(4-)
(3-)
   167.09A C (6-)      69.60
 
(M1+E2)
    97.49
(5-)
   175.13 BC (1+) 42 ns 2     50.12
   71.30
  175.12
   22 3 
  100 10 
    6.5 14 
(E1)
(E1)
[E1+M2]
   125.01
   103.83
     0.0
(2-)
(1-)
2-
E(level)
(keV)
XREFJπ(level) T1/2(level)E(γ)
(keV)
I(γ)M(γ)Final Levels
   179.99  C (3-)     145.56
  179.99
 
 
(M1)
(M1+E2)
    34.47
     0.0
(3-)
2-
   190 2 A   (7+)        
   203.64  C (4-)     123.37
  169.19
 
 
(M1)
(M1)
    80.26
    34.47
(4-)
(3-)
   211.82 BC 2+      36.7S
   96.38
  177.36
  211.82
 
    5.9 7 
   59 6 
  100 10 

(M1)
(E1)
E1
   175.13
   115.45
    34.47
     0.0
(1+)
(3+)
(3-)
2-
   215.94  C (0+)      40.82
  112.116
 
 
(M1)
(E1)
   175.13
   103.83
(1+)
(1-)
   236.74 BC (3+)     121.29
  202.27
 
 
(M1)

   115.45
    34.47
(3+)
(3-)
   241 2 A   (9+)      85.1 1 
 
(M1,E2)
   156
(8+)
   247.9 2 A   (7-)      80.8 1 
  150 2 
 
 
(M1,E2)

   167.09
    97.49
(6-)
(5-)
   270.46 BC (4+)      58.64
  235.98
 
 
(E2)

   211.82
    34.47
2+
(3-)
   298 2  B         
   316 3  B  (5+)        
   316.46  C (5+)     238.14
  280.88
 
 
(M1)
(M1)
    78.33
    35.59
(5+)
(4+)
   325 2 A       233 2 ?
  249 2 
   32 4 
  100 16 


    97.49
    78.33
(5-)
(5+)
   333 2 A          
  ≈341A          
   369.61  C (6+)     239.18
  291.36
 
 
(M1)
(M1)
   130.49
    78.33
(6+)
(5+)
   406  C (6+)        
   413 3 A       316 2 
 

    97.49
(5-)
E(level)
(keV)
XREFJπ(level) T1/2(level)E(γ)
(keV)
I(γ)M(γ)Final Levels
   471 2 A       304 2 
 

   167.09
(6-)
   526  C        
   527 20 A          
   552  C        
   566  C        

E(level): From 275.7-d and 39.3H 254Es α decay and from 249Bk(n,γ) reaction studies.

T1/2(level): Excited states’ half-lives are from 275.7-d and 39.3H 254Es α decay

E(γ): From (n,γ), 276-d and 39.3H 254Es α decays.

I(γ): Relative photon intensities deexciting each level. These branchings are deduced from Iγ’s measured in 254Es α decays.

M(γ): Deduced in 254Es α decays and (n,γ) work.

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Band Transitions:

E(level)
(keV)
Jπ(level) T1/2(level)E(γ)I(γ)M(γ)Final Levels
Band 1 - K=2.
     0.0 2- 3.212 h 5 
% β- = 100
     
    34.47 (3-)      34.47
 
(M1,E2)
     0.0
2-
    80.26 (4-)      45.79
   80.26
 
 
(M1+E2)
(E2)
    34.47
     0.0
(3-)
2-
   137.32 (5-)      57.06
  102.84
 
 
(M1)
(E2)
    80.26
    34.47
(4-)
(3-)
E(level)
(keV)
Jπ(level) T1/2(level)E(γ)I(γ)M(γ)Final Levels
Band 2 - K=4.
    35.59 (4+) 29 µs 1       
    78.33 (5+)      42.74
 
(M1+E2)
    35.59
(4+)
   130.49 (6+)      52.16
   94.91
 
 
(M1+E2)
(E2)
    78.33
    35.59
(5+)
(4+)
   190 2  (7+)     
E(level)
(keV)
Jπ(level) T1/2(level)E(γ)I(γ)M(γ)Final Levels
Band 3 - K=7.
    86 2  (7+) 213 µs 8       
   156 2  (8+)      70.4 2 
 
(M1+E2)
    86
(7+)
   241 2  (9+)      85.1 1 
 
(M1,E2)
   156
(8+)
E(level)
(keV)
Jπ(level) T1/2(level)E(γ)I(γ)M(γ)Final Levels
Band 4 - K=5.
    97.49 (5-) 38 ns 5       
   167.09 (6-)      69.60
 
(M1+E2)
    97.49
(5-)
   247.9 2  (7-)      80.8 1 
  150 2 
 
 
(M1,E2)

   167.09
    97.49
(6-)
(5-)
E(level)
(keV)
Jπ(level) T1/2(level)E(γ)I(γ)M(γ)Final Levels
Band 5 - K=1.
   103.83 (1-)        
   125.01 (2-)      90.53
  125.01
  100 30 
   75 30 
(M1)
(M1)
    34.47
     0.0
(3-)
2-
   157.39 (3-)      53.59
   77.13
  122.95
 
 
 
(E2)
(M1)
(M1)
   103.83
    80.26
    34.47
(1-)
(4-)
(3-)
   203.64 (4-)     123.37
  169.19
 
 
(M1)
(M1)
    80.26
    34.47
(4-)
(3-)
E(level)
(keV)
Jπ(level) T1/2(level)E(γ)I(γ)M(γ)Final Levels
Band 6 - K=3.
   115.45 (3+)        
   148.60 (4+)      70.27
  113.01
 
 
(M1)
(M1)
    78.33
    35.59
(5+)
(4+)
E(level)
(keV)
Jπ(level) T1/2(level)E(γ)I(γ)M(γ)Final Levels
Band 7 - K=2.
   146.43 (2-)        
   179.99 (3-)     145.56
  179.99
 
 
(M1)
(M1+E2)
    34.47
     0.0
(3-)
2-
E(level)
(keV)
Jπ(level) T1/2(level)E(γ)I(γ)M(γ)Final Levels
Band 8 - K=2.
   211.82 2+        
   236.74 (3+)     121.29
  202.27
 
 
(M1)

   115.45
    34.47
(3+)
(3-)
   270.46 (4+)      58.64
  235.98
 
 
(E2)

   211.82
    34.47
2+
(3-)
   316 3  (5+)     
E(level)
(keV)
Jπ(level) T1/2(level)E(γ)I(γ)M(γ)Final Levels
Band 9 - K=5.
   316.46 (5+)        
   369.61 (6+)     239.18
  291.36
 
 
(M1)
(M1)
   130.49
    78.33
(6+)
(5+)

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Additional Gamma Data:













E(level)
(keV)
Jπ(level)T1/2(level)E(γ)
(keV)
MultipolarityConversion
Coefficient
Additional Data
    34.47 (3-)      34.47(M1,E2)18×102α=18×102 16
    35.59 (4+) 29 µs 1      1.12[E1]B(E1)(W.u.)≈1E-6
(4+) 29 µs 1     35.59(M2)1.287×104B(M2)(W.u.)≈0.026, α=1.287×104
    86 (7+) 213 µs 8      8[E2]1.3×106B(E2)(W.u.)=0.0007 5, α=1.3E6
    97.49 (5-) 38 ns 5     61.91(E1)0.508B(E1)(W.u.)=1.25E-5 18, α=0.508
   103.83 (1-)     103.83(M1)7.47α=7.47
   115.45 (3+)      79.86(M1)16.05α=16.05
   125.01 (2-)      90.53(M1)11.13α=11.13
(2-)     125.01(M1)4.38α=4.38
   130.49 (6+)      52.16(M1+E2)2.6×102α=2.6×102 20
(6+)      94.91(E2)26.7α=26.7
   137.32 (5-)      57.06(M1)42.8α=42.8
(5-)     102.84(E2)18.4α=18.4
   146.43 (2-)     111.96(M1)6.01α=6.01
(2-)     146.43(M1+E2)8.3α=8.3 41
   148.60 (4+)      70.27(M1)23.3α=23.3
(4+)     113.01(M1)5.85α=5.85
   156 (8+)      70.4 2 (M1+E2)66α=66 43
   157.39 (3-)      53.59(E2)402.8α=402.8
(3-)      77.13(M1)17.78α=17.78
(3-)     122.95(M1)4.59α=4.59
   167.09 (6-)      69.60(M1+E2)69α=69 24
   175.13 (1+) 42 ns 2     50.12(E1)0.882B(E1)(W.u.)=3.5E-6 7, α=0.882
(1+) 42 ns 2     71.30(E1)0.352B(E1)(W.u.)=5.6E-6 8, α=0.352
(1+) 42 ns 2    175.12[E1+M2]2.76B(E1)(W.u.)=2.2E-8 6, B(M2)(W.u.)=0.30 8, α=2.76
E(level)
(keV)
Jπ(level)T1/2(level)E(γ)
(keV)
MultipolarityConversion
Coefficient
Additional Data
   179.99 (3-)     145.56(M1)12.9α=12.9
(3-)     179.99(M1+E2)4.3α=4.3 27
   203.64 (4-)     123.37(M1)4.55α=4.55
(4-)     169.19(M1)8.40α=8.40
   211.82 2+      96.38(M1)9.28α=9.28
2+     177.36(E1)0.145α=0.145
2+     211.82E10.0967α=0.0967
   215.94 (0+)      40.82(M1)113.7α=113.7
(0+)     112.116(E1)0.109α=0.109
   236.74 (3+)     121.29(M1)4.78α=4.78
   270.46 (4+)      58.64(E2)261α=261
   316.46 (5+)     238.14(M1)3.21α=3.21
(5+)     280.88(M1)2.03α=2.03
   369.61 (6+)     239.18(M1)3.17α=3.17
(6+)     291.36(M1)1.81α=1.81

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Additional Level Data and Comments:

E(level)Jπ(level)T1/2(level)Comments
     0.02- 3.212 h 5 
% β- = 100
Among the available Nilsson orbitals, analogy to 251Bk and 251Cf for the proton and neutron states suggests that probable configuration is 2-,(p 3/2[521]+n 1/2[620]).
E(level): Among the available Nilsson orbitals, analogy to 251Bk and 251Cf for the proton and neutron states suggests that probable configuration is 2-,(p 3/2[521]+n 1/2[620]). K=2.
    34.47(3-)   E(level): K=2.
    35.59(4+) 29 µs 1  E(level): K=4.
    78.33(5+)   E(level): K=4.
    80.26(4-)   E(level): K=2.
    86(7+) 213 µs 8  E(level): K=7.
    97.49(5-) 38 ns 5  E(level): K=5.
   103.83(1-)   E(level): K=1.
   115.45(3+)   Another reason for adopting this order is that if the 3+ state were at 131.97 keV, the rotational band parameter would Be much too small, assuming the assignment of the 148.60-keV level as the band’s 4+ member is correct.
E(level): Another reason for adopting this order is that if the 3+ state were at 131.97 keV, the rotational band parameter would Be much too small, assuming the assignment of the 148.60-keV level as the band’s 4+ member is correct. K=3.
   125.01(2-)   E(level): K=1.
   130.49(6+)   E(level): K=4.
   137.32(5-)   E(level): K=2.
   146.43(2-)   E(level): K=2.
   148.60(4+)   E(level): K=3.
   156(8+)   E(level): K=7.
   157.39(3-)   E(level): K=1.
   167.09(6-)   E(level): K=5.
   179.99(3-)   E(level): K=2.
   190(7+)   E(level): K=4.
   203.64(4-)   E(level): K=1.
   211.822+   E(level): K=2.
   236.74(3+)   E(level): K=2.
   241(9+)   E(level): K=7.
   247.9(7-)   E(level): K=5.
   270.46(4+)   E(level): K=2.
E(level)Jπ(level)T1/2(level)Comments
   316(5+)   E(level): K=2.
   316.46(5+)   E(level): K=5.
   369.61(6+)   E(level): K=5.
   413   E(level): The authors of 1966Mc02 tentatively suggested that the 413-,471- and 527-keV levels might Be members of a rotational band. They may possibly Be the 6+, 7+ and 8+ members of the K=6 band, identified at 406 keV.
   471   E(level): The authors of 1966Mc02 tentatively suggested that the 413-,471- and 527-keV levels might Be members of a rotational band. They may possibly Be the 6+, 7+ and 8+ members of the K=6 band, identified at 406 keV.
   527   E(level): The authors of 1966Mc02 tentatively suggested that the 413-,471- and 527-keV levels might Be members of a rotational band. They may possibly Be the 6+, 7+ and 8+ members of the K=6 band, identified at 406 keV.

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Additional Gamma Comments:

E(level)E(gamma)Comments
   211.82    36.7E(γ): from level scheme.
   236.74   202.27E(γ): deduced from level energies shown in 1982HoZE. γ energy was not given in the decay scheme of 1982HoZE.

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