ADOPTED LEVELS, GAMMAS for 251Fm

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-)=-3013 keV 24S(n)= 6190 keV 17S(p)= 4562 keV SYQ(α)= 7425.1 keV 20
Reference: 2012WA38

References:
  A  255No α decay 

General Comments:

Calculations, compilations:

Favored α decays: 1992Bu03, 1993Bu09, 2003Re32

Ground state properties: 1997Mo25, 1995Mo29

2005Pa73: Calculated deformation, pairing.

Single-particle Nilsson levels: 2006Sh19, 2005Pa73, 1994Cw02

SF Half-life: 2005Re16

Q(α), T1/2: 2012Po01, 2011He12, 2011Zh36, 2010Ni02, 2010Si27, 2009Do22, 2009Sa25, 2008Do12, 2005Ga25, 2003Re32

Neutron Separation Energies: 2004Pa31

1994Cw02 calculated the following single-particle level sequence: g.s. 9/2[734], 0.21 MeV 7/2[624], 0.44 MeV 5/2[622], 0.65 MeV 1/2[620], 0.79 MeV 3/2[622], 0.89 MeV 7/2[613], 1.03 MeV 11/2[725]

Assignment: 249Cf(α,2n) chem, excit (1957Am47,1973Ah02)

Q-value: Estimated ΔS(p)=101 (2012Wa38)










E(level)
(keV)
XREFJπ(level) T1/2(level)E(γ)
(keV)
I(γ)M(γ)Final Levels
    0.0A (9/2-) 5.30 h 8 
% ε = 98.20 13
% α = 1.80 13
     
   63.9 8 A 11/2-      63.9 8 
  100
M1
    0.0
(9/2-)
  200.0 1 A 5/2+ 21.1 µs 19    200.0 1 
  100
M2
    0.0
(9/2-)
  243 3 A 7/2+        
  301 3 A 9/2+        
  353.9 4 A (7/2+)     353.9 4 
  100
[E1]
    0.0
(9/2-)
  391.8 2 A 1/2+ 22 ns 3    192.0 2 
  100
(E2)
  200.0
5/2+
  395.05 18 A 3/2+ < 16 ns     3.4 3 S
  194.9 2 
 
  100
[M1]
M1
  391.8
  200.0
1/2+
5/2+
  461 3 A 5/2+        
  558.43 18 A 1/2+ < 8 ns   163.3 2 
  166.7 2 
  358.4 2 
   35 9 
   16 6 
  100 20 
(M1)
[M1]
[E2]
  395.05
  391.8
  200.0
3/2+
1/2+
5/2+
  579 5 A 3/2+        
  604 4 A 5/2+        

E(level): From 255No α decay

Jπ(level): Assignments of Jπ and rotational bands are those proposed in 2011As03. They are based on analogy with n=151 nuclei (249Cf and 247Cm) and rotational structure, on γ-ray multipolarities, and α-decay hindrance factors.

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Band Transitions:

E(level)
(keV)
Jπ(level) T1/2(level)E(γ)I(γ)M(γ)Final Levels
Band 1 - ROTATIONAL band ν9/2[734]
    0.0 (9/2-) 5.30 h 8 
% ε = 98.20 13
% α = 1.80 13
     
   63.9 8  11/2-      63.9 8 
  100
M1
    0.0
(9/2-)
E(level)
(keV)
Jπ(level) T1/2(level)E(γ)I(γ)M(γ)Final Levels
Band 2 - ROTATIONAL band ν5/2[622]
  200.0 1  5/2+ 21.1 µs 19       
  243 3  7/2+     
  301 3  9/2+     
E(level)
(keV)
Jπ(level) T1/2(level)E(γ)I(γ)M(γ)Final Levels
Band 3 - ROTATIONAL band ν1/2[631]
  391.8 2  1/2+ 22 ns 3       
  395.05 18  3/2+ < 16 ns     3.4 3 S
  194.9 2 
 
  100
[M1]
M1
  391.8
  200.0
1/2+
5/2+
  461 3  5/2+     
E(level)
(keV)
Jπ(level) T1/2(level)E(γ)I(γ)M(γ)Final Levels
Band 4 - ROTATIONAL band ν1/2[620]
  558.43 18  1/2+ < 8 ns      
  579 5  3/2+     
  604 4  5/2+     

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Additional Gamma Data:













E(level)
(keV)
Jπ(level)T1/2(level)E(γ)
(keV)
MultipolarityConversion
Coefficient
Additional Data
   63.9 11/2-      63.9 8 M138.7α=38.7 16, α(L)=28.9 12, α(M)=7.2 3, α(N)=2.00 8, α(O)=0.528 22, α(P)=0.103 5, α(Q)=0.00579 24, α(N+)=2.64 11
  200.0 5/2+ 21.1 µs 19    200.0 1 M223.8B(M2)(W.u.)=0.0047 5, α=23.8, α(K)=14.49 21, α(L)=6.75 10, α(M)=1.85 3, α(N)=0.528 8, α(O)=0.1393 20, α(P)=0.0261 4, α(Q)=0.001339 19, α(N+)=0.695 10
  353.9 (7/2+)     353.9 4 [E1]0.0342α=0.0342, α(K)=0.0266 4, α(L)=0.00566 8, α(M)=0.001390 20, α(N)=0.000386 6, α(O)=0.0001002 15, α(P)=1.84×10-5 3, α(Q)=8.23E-7 12, α(N+)=0.000505 8
  391.8 1/2+ 22 ns 3    192.0 2 (E2)1.565B(E2)(W.u.)=0.41 6, α=1.565, α(K)=0.1385 20, α(L)=1.026 15, α(M)=0.293 5, α(N)=0.0832 13, α(O)=0.0211 4, α(P)=0.00346 5, α(Q)=2.49E-5 4, α(N+)=0.1078 16
  395.05 3/2+ < 16 ns     3.4 3 [M1]1.6×104α=1.6×104 5, α(N)=1.2E4 4, α(O)=3.2E3 11, α(P)=6.2E2 20, α(Q)=36 12, α(N+)=1.6E4 5
3/2+ < 16 ns   194.9 2 M16.86B(M1)(W.u.)>2.3×10-5, α=6.86, α(K)=5.31 8, α(L)=1.157 17, α(M)=0.286 4, α(N)=0.0798 12, α(O)=0.0211 3, α(P)=0.00409 6, α(Q)=0.000229 4, α(N+)=0.1052 15
  558.43 1/2+ < 8 ns   163.3 2 (M1)11.30B(M1)(W.u.)>3.0×10-5, α=11.30, α(K)=8.74 13, α(L)=1.91 3, α(M)=0.473 7, α(N)=0.1320 19, α(O)=0.0349 5, α(P)=0.00677 10, α(Q)=0.000379 6, α(N+)=0.174 3
1/2+ < 8 ns   166.7 2 [M1]10.66B(M1)(W.u.)>1.3×10-5, α=10.66, α(K)=8.25 12, α(L)=1.80 3, α(M)=0.446 7, α(N)=0.1245 18, α(O)=0.0329 5, α(P)=0.00638 10, α(Q)=0.000357 6, α(N+)=0.1641 24
1/2+ < 8 ns   358.4 2 [E2]0.181B(E2)(W.u.)>0.017, α=0.181, α(K)=0.0651 10, α(L)=0.0843 12, α(M)=0.0235 4, α(N)=0.00664 10, α(O)=0.001698 24, α(P)=0.000290 4, α(Q)=4.57E-6 7, α(N+)=0.00863 13

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Additional Level Data and Comments:

E(level)Jπ(level)T1/2(level)Comments
    0.0(9/2-) 5.30 h 8 
% ε = 98.20 13
% α = 1.80 13
E(level): ROTATIONAL band ν9/2[734].
   63.911/2-   E(level): ROTATIONAL band ν9/2[734].
  200.05/2+ 21.1 µs 19  E(level): ROTATIONAL band ν5/2[622].
  2437/2+   E(level): ROTATIONAL band ν5/2[622].
  3019/2+   E(level): ROTATIONAL band ν5/2[622].
  391.81/2+ 22 ns 3  E(level): ROTATIONAL band ν1/2[631].
  395.053/2+ < 16 ns E(level): ROTATIONAL band ν1/2[631].
  4615/2+   E(level): ROTATIONAL band ν1/2[631].
  558.431/2+ < 8 ns E(level): ROTATIONAL band ν1/2[620].
  5793/2+   E(level): ROTATIONAL band ν1/2[620].
  6045/2+   E(level): ROTATIONAL band ν1/2[620].

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Additional Gamma Comments:

E(level)E(gamma)Comments
  395.05    3.4E(γ): existence of this transition is suggested in 2011As03 from the intensity imbalances between the 191.91-166.7 keV cascade and the 195.3-163.3 keV γγ cascades (2011As03).

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