ADOPTED LEVELS, GAMMAS for 251Es

Authors: E. Browne, J. K. Tuli |  Citation: Nucl. Data Sheets 114, 1041 (2013) |  Cutoff date: 1-Jan-2012 

 Full ENSDF file | Adopted Levels (PDF version) 


Q(β-)=-1440 keV 16S(n)= 6785 keV SYS(p)= 3947 keV 6Q(α)= 6598 keV 3
Reference: 2012WA38

References:
  A  251Fm ε decay  B  255Md α decay
  C  250Cf(α,t) 

General Comments:

Calculations, compilations:

Favored α decay: 1993Bu09, 1992Bu03

Ground-state properties: 1997Mo25, 1995Mo29

Heavy cluster spontaneous emission: 1985Po15

Deformation, Pairing gap, Single-particle energies: 2004Pa40

Single-particle Nilsson levels: 1994Cw02, 2010Ad19

Alpha decay, t, branching ratios: 2010Ni02

Q(α), T1/2: 2011Sa20, 2008Do12

1994Cw02 calculated the following single-particle level sequence: g.s. 7/2[633], 0.30 MeV 3/2[521], 0.35 MeV 1/2[521], 0.73 MeV 7/2[514], 0.79 MeV 5/2[642], 0.80 MeV 1/2[660]

2004Pa40 calculated the following single-particle level sequence: g.s. 7/2[633], 0.20 MeV 3/2[521], 0.20 MeV 1/2[521], 0.55 MeV 1/2[400], 0.58 MeV 5/2[642], 0.60 MeV 7/2[514]

Gammas: All γ-ray data are from 251Fm ε decay (1978Ah02)

Q-value: Estimated ΔS(n)=100 (2012Wa38)










E(level)
(keV)
XREFJπ(level) T1/2(level)E(γ)
(keV)
I(γ)M(γ)Final Levels
     0  C 3/2- 33 h 1 
% ε = 99.5 2
% α = 0.5 2
     
     8.4 10 AB  (7/2+)        8.3S
 

     0
3/2-
    31.7 10 ABC 5/2-        
    55.8 10 AB  (9/2+)       47.48 6 
 
M1+E2
     8.4
(7/2+)
    76.2 11 A C 7/2-        
   114.1 10 A   (11/2+)        
   182.5 10 A C (13/2+)        
   263.0 11 A   (15/2+)        
   411 2   C (1/2-)        
   452 2   C (5/2-)        
   461.5 10 AB  7/2-      385.3 2 
   405.6 1 
   429.7 1 
   453.1 1 
    2.1 2 
   68 4 
    5.7 5 
  100 6 
(M1)
(E1+M2)
M1+E2
(E1+M2)
    76.2
    55.8
    31.7
     8.4
7/2-
(9/2+)
5/2-
(7/2+)
   515.5? B         
   523.9 10  BC (9/2-)        
   548 2   C (7/2-,9/2-)        
   661 3   C (1/2+)        
   778.0 10 A   (9/2+)      664.0 3 
   722.1 2 
   769.6 1 
    4.3 8 
   21 2 
  100 5 
(M1,E2)
(M1+E2)
(M1)
   114.1
    55.8
     8.4
(11/2+)
(9/2+)
(7/2+)
   889.1 10 A   (11/2+)      706.3 2 
   775.0 1 
   833.3 1 
   880.8 1 
    1.12 13 
   ≈3.9
   29 2 
  100 5 
(M1)

(E2+M1)
E2
   182.5
   114.1
    55.8
     8.4
(13/2+)
(11/2+)
(9/2+)
(7/2+)
   942 4   C (13/2+)        
   957.5 10 A C (13/2+)      694.5 3 
   775.0 1 
   843.4 1 
   901.6 1 
   12 3 
  ≈32
   92 8 
  100 8 


(M1+E2)

   263.0
   182.5
   114.1
    55.8
(15/2+)
(13/2+)
(11/2+)
(9/2+)
E(level)
(keV)
XREFJπ(level) T1/2(level)E(γ)
(keV)
I(γ)M(γ)Final Levels
  1239.0 10 A   (11/2+)      281.4 1 
   349.9 1 
   461.0 1 
  1056.2 4 
  1124.9 2 
  1183.0 2 
  1230.6 2 
    8.6 6 
  100 5 
   11.0 7 
    0.7 1 
    3.3 4 
    8.8 6 
   16.7 12 
M1(+E2)
M1
(M1)




   957.5
   889.1
   778.0
   182.5
   114.1
    55.8
     8.4
(13/2+)
(11/2+)
(9/2+)
(13/2+)
(11/2+)
(9/2+)
(7/2+)
  1264.9 10 A   (11/2+)      307.4 1 
   375.8 1 
   487.1 2 
  1151.0 2 
  1209.1 2 
  1256.6 2 
    9.7 8 
  100 6 
    3.0 6 
    4.1 6 
    9.5 8 
   17.6 14 
M1+E2
M1




   957.5
   889.1
   778.0
   114.1
    55.8
     8.4
(13/2+)
(11/2+)
(9/2+)
(11/2+)
(9/2+)
(7/2+)
  1301.4 11 A   (7/2+,9/2,11/2)     1245.6 4 
  1293.0 3 
   16 2 
  100 8 


    55.8
     8.4
(9/2+)
(7/2+)
  1307.2 10 A   (7/2+,9/2,11/2+)     1193.0 2 
  1251.2 2 
  1298.8 3 
   21 2 
   45 4 
  100 7 



   114.1
    55.8
     8.4
(11/2+)
(9/2+)
(7/2+)
  1357.0 11 A   (7/2+,9/2,11/2+)     1242.8 4 
  1301.2 3 
  1348.6 3 
  100 10 
  190 19 
   63 6 



   114.1
    55.8
     8.4
(11/2+)
(9/2+)
(7/2+)

E(level): The level energies from 251Fm ε decay have been deduced from least-squares fit to Eγ (with E(5/2- level)=31.7 2 calculated from rotational parameter). Levels not seen in 255Md α decay, or 251Fm ε decay are from the (α,t) reaction.

Jπ(level): The band assignments are those proposed by 1978Ah02 on the basis of the results in 251Fm ε decay and 250Cf(α,t).

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Band Transitions:

E(level)
(keV)
Jπ(level) T1/2(level)E(γ)I(γ)M(γ)Final Levels
Band 1 - 3/2-[521].
     0 3/2- 33 h 1 
% ε = 99.5 2
% α = 0.5 2
     
    31.7 10  5/2-     
    76.2 11  7/2-        
E(level)
(keV)
Jπ(level) T1/2(level)E(γ)I(γ)M(γ)Final Levels
Band 2 - 7/2+[633].
     8.4 10  (7/2+)        
    55.8 10  (9/2+)       47.48 6 
 
M1+E2
     8.4
(7/2+)
   114.1 10  (11/2+)        
   182.5 10  (13/2+)     
   263.0 11  (15/2+)        
E(level)
(keV)
Jπ(level) T1/2(level)E(γ)I(γ)M(γ)Final Levels
Band 3 - 1/2-[521].
   411 2  (1/2-)        
   452 2  (5/2-)     
   548 2  (7/2-,9/2-)        
E(level)
(keV)
Jπ(level) T1/2(level)E(γ)I(γ)M(γ)Final Levels
Band 4 - 7/2-[514].
   461.5 10  7/2-        
   523.9 10  (9/2-)     
E(level)
(keV)
Jπ(level) T1/2(level)E(γ)I(γ)M(γ)Final Levels
Band 5 - 1/2+[400]
   661 3  (1/2+)        
E(level)
(keV)
Jπ(level) T1/2(level)E(γ)I(γ)M(γ)Final Levels
Band 6 - 9/2+[624].
   778.0 10  (9/2+)        
   942 4  (13/2+)     
E(level)
(keV)
Jπ(level) T1/2(level)E(γ)I(γ)M(γ)Final Levels
Band 7 - 7/2+[633]+2+ VIB, Kπ=11/2+.
   889.1 10  (11/2+)        
   957.5 10  (13/2+)      694.5 3 
   775.0 1 
   843.4 1 
   901.6 1 
   12 3 
  ≈32
   92 8 
  100 8 


(M1+E2)

   263.0
   182.5
   114.1
    55.8
(15/2+)
(13/2+)
(11/2+)
(9/2+)

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Additional Gamma Data:















E(level)
(keV)
Jπ(level)T1/2(level)E(γ)
(keV)
MultipolarityMixing
Ratio
Conversion
Coefficient
Additional Data
    55.8 (9/2+)       47.48 6 M1+E20.18 7107α=107 21, α(L)=79 15, α(M)=20 5, α(N)=5.7 13, α(O)=1.5 3, α(P)=0.27 5, α(Q)=0.0123 3, α(N+)=7.4 16
   461.5 7/2-      385.3 2 (M1) 0.938α=0.938, α(K)=0.731 11, α(L)=0.1550 22, α(M)=0.0381 6, α(N)=0.01060 15, α(O)=0.00277 4, α(P)=0.000537 8, α(Q)=3.06×10-5 5, α(N+)=0.01394 20
7/2-      405.6 1 (E1+M2)0.160 130.078α=0.078 9, α(K)=0.057 7, α(L)=0.0159 20, α(M)=0.0041 5, α(N)=0.00114 15, α(O)=0.00030 4, α(P)=5.6×10-5 8, α(Q)=3.0E-6 4, α(N+)=0.00150 19
7/2-      429.7 1 M1+E20.56 300.55α=0.55 11, α(K)=0.42 10, α(L)=0.097 14, α(M)=0.024 4, α(N)=0.0067 9, α(O)=0.00175 24, α(P)=0.00034 5, α(Q)=1.8×10-5 4, α(N+)=0.0088 12
7/2-      453.1 1 (E1+M2)0.220 150.090α=0.090 10, α(K)=0.065 7, α(L)=0.0183 21, α(M)=0.0047 6, α(N)=0.00132 15, α(O)=0.00034 4, α(P)=6.5×10-5 8, α(Q)=3.5E-6 4, α(N+)=0.00173 20
   778.0 (9/2+)      664.0 3 (M1,E2) 0.12α=0.12 9, α(K)=0.09 8, α(L)=0.023 13, α(M)=0.006 3, α(N)=0.0016 9, α(O)=0.00041 22, α(P)=8.E-5 5, α(Q)=4.E-6 3, α(N+)=0.0021 11
(9/2+)      722.1 2 (M1+E2)0.6 30.13α=0.13 3, α(K)=0.103 21, α(L)=0.023 4, α(M)=0.0056 9, α(N)=0.00155 24, α(O)=0.00040 7, α(P)=7.8×10-5 13, α(Q)=4.3E-6 9, α(N+)=0.0020 4
(9/2+)      769.6 1 (M1) 0.1429α=0.1429, α(K)=0.1117 16, α(L)=0.0234 4, α(M)=0.00573 8, α(N)=0.001592 23, α(O)=0.000417 6, α(P)=8.07×10-5 12, α(Q)=4.60E-6 7, α(N+)=0.00209 3
   889.1 (11/2+)      706.3 2 (M1) 0.180α=0.180, α(K)=0.1407 20, α(L)=0.0295 5, α(M)=0.00724 11, α(N)=0.00201 3, α(O)=0.000527 8, α(P)=0.0001019 15, α(Q)=5.81×10-6 9, α(N+)=0.00265 4
(11/2+)      833.3 1 (E2+M1)2.1 +5-30.040α=0.040 6, α(K)=0.030 5, α(L)=0.0080 8, α(M)=0.00202 18, α(N)=0.00056 5, α(O)=0.000146 14, α(P)=2.7×10-5 3, α(Q)=1.26E-6 17, α(N+)=0.00074 7
(11/2+)      880.8 1 E2 0.0209α=0.0209, α(K)=0.01447 21, α(L)=0.00476 7, α(M)=0.001231 18, α(N)=0.000344 5, α(O)=8.86×10-5 13, α(P)=1.627E-5 23, α(Q)=6.28E-7 9, α(N+)=0.000449 7
   957.5 (13/2+)      843.4 1 (M1+E2)0.8 30.077α=0.077 17, α(K)=0.059 14, α(L)=0.0132 25, α(M)=0.0033 6, α(N)=0.00091 17, α(O)=0.00024 5, α(P)=4.5×10-5 9, α(Q)=2.5E-6 6, α(N+)=0.00119 22
  1239.0 (11/2+)      281.4 1 M1(+E2)0.4 21.98α=1.98 24, α(K)=1.51 21, α(L)=0.347 23, α(M)=0.086 5, α(N)=0.0240 14, α(O)=0.0063 4, α(P)=0.00120 9, α(Q)=6.4×10-5 9, α(N+)=0.0316 18
(11/2+)      349.9 1 M1 1.223α=1.223, α(K)=0.953 14, α(L)=0.202 3, α(M)=0.0498 7, α(N)=0.01384 20, α(O)=0.00363 5, α(P)=0.000702 10, α(Q)=4.00×10-5 6, α(N+)=0.0182 3
(11/2+)      461.0 1 (M1) 0.574α=0.574, α(K)=0.447 7, α(L)=0.0946 14, α(M)=0.0232 4, α(N)=0.00646 9, α(O)=0.001691 24, α(P)=0.000327 5, α(Q)=1.87×10-5 3, α(N+)=0.00850 12
  1264.9 (11/2+)      307.4 1 M1+E20.5 21.45α=1.45 20, α(K)=1.11 17, α(L)=0.260 20, α(M)=0.065 5, α(N)=0.0181 12, α(O)=0.0047 4, α(P)=0.00090 8, α(Q)=4.7×10-5 7, α(N+)=0.0237 16
(11/2+)      375.8 1 M1 1.005α=1.005, α(K)=0.783 11, α(L)=0.1661 24, α(M)=0.0408 6, α(N)=0.01136 16, α(O)=0.00297 5, α(P)=0.000575 8, α(Q)=3.28×10-5 5, α(N+)=0.01494 21

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Additional Level Data and Comments:

E(level)Jπ(level)T1/2(level)Comments
     03/2- 33 h 1 
% ε = 99.5 2
% α = 0.5 2
E(level): 3/2-[521].
     8.4(7/2+)   E(level): 7/2+[633].
    31.75/2-   E(level): 3/2-[521].
    55.8(9/2+)   E(level): 7/2+[633].
    76.27/2-   E(level): 3/2-[521].
   114.1(11/2+)   E(level): 7/2+[633].
   182.5(13/2+)   E(level): 7/2+[633].
   263.0(15/2+)   E(level): 7/2+[633].
   411(1/2-)   E(level): 1/2-[521].
Jπ(level): From comparison of (α,t) spectroscopic factors with Nilsson model calculations, the 411, 452 and 548 levels belong to the 1/2[521] rotational band.
   452(5/2-)   E(level): 1/2-[521].
Jπ(level): From comparison of (α,t) spectroscopic factors with Nilsson model calculations, the 411, 452 and 548 levels belong to the 1/2[521] rotational band.
   461.57/2-   E(level): 7/2-[514].
   523.9(9/2-)   E(level): 7/2-[514].
   548(7/2-,9/2-)   E(level): 1/2-[521].
Jπ(level): From comparison of (α,t) spectroscopic factors with Nilsson model calculations, the 411, 452 and 548 levels belong to the 1/2[521] rotational band.
   661(1/2+)   E(level): 1/2+[400].
   778.0(9/2+)   E(level): 9/2+[624].
   889.1(11/2+)   E(level): 7/2+[633]+2+ VIB, Kπ=11/2+.
   942(13/2+)   E(level): 9/2+[624].
   957.5(13/2+)   E(level): 7/2+[633]+2+ VIB, Kπ=11/2+.

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