List of levels for 251FM

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

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), T_1/2: 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): From ²⁵⁵No α decay

J^π(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.

E(level) (keV)	J^π(level)	T_1/2(level)	E(γ) (keV)	Multipolarity	Conversion Coefficient	Additional Data
63.9	11/2-		63.9 8	M1	38.7	α=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	M2	23.8	B(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]	0.0342	α=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)	1.565	B(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]	1.6×10⁴	α=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
395.05	3/2+	< 16 ns	194.9 2	M1	6.86	B(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)	11.30	B(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]	10.66	B(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]	0.181	B(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

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

E(level) (keV)	XREF	J^π(level)	T_1/2(level)	E(γ) (keV)	I(γ)	M(γ)	Final Levels
0.0	A	(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)	J^π(level)	T_1/2(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].
63.9	11/2-		E(level): ROTATIONAL band ν9/2[734].
200.0	5/2+	21.1 µs 19	E(level): ROTATIONAL band ν5/2[622].
243	7/2+		E(level): ROTATIONAL band ν5/2[622].
301	9/2+		E(level): ROTATIONAL band ν5/2[622].
391.8	1/2+	22 ns 3	E(level): ROTATIONAL band ν1/2[631].
395.05	3/2+	< 16 ns	E(level): ROTATIONAL band ν1/2[631].
461	5/2+		E(level): ROTATIONAL band ν1/2[631].
558.43	1/2+	< 8 ns	E(level): ROTATIONAL band ν1/2[620].
579	3/2+		E(level): ROTATIONAL band ν1/2[620].
604	5/2+		E(level): ROTATIONAL band ν1/2[620].

E(level)	E(gamma)	Comments
395.05	3.4	E(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).