List of levels for 256FM

ADOPTED LEVELS, GAMMAS for ²⁵⁶Fm

Author: Balraj Singh | Citation: Nucl. Data Sheets 141, 327 (2017) | Cutoff date: 22-Mar-2017

Full ENSDF file | Adopted Levels (PDF version)

Q(β-)=-1970 keV SY	S(n)= 6384 keV 7	S(p)= 5891 keV 12	Q(α)= 7027 keV 5
Reference: 2017WA10

References:
A	²⁵⁶Es β^- decay (25.4 M)	B	²⁵⁶Es β^- decay (7.6 H)
C	²⁵⁶Md ε decay (77.7 M)

1955Ch30 produced and identified ²⁵⁶Fm in neutron irradiation of ²⁵⁵Es, and β^- decay of ²⁵⁶Es at Berkeley. Measured half-life from decay curve for spontaneous fission. Later studies: of ²⁵⁶Fm decay: 1958Ph40, 1965Si14, 1968Ho13, 1972Fl04, 1981Lo15

Theoretical calculations: consult the Nuclear Science References (NSR) database for about 200 theory references.

2014Sh07, 2013Af01, 2013Pr08, 2012Jo05: nuclear structure theory references

Levels: Assignments to band members are from depopulation patterns, and energy fit to rotational bands.

Q-value: Estimated uncertainty=120 for Q(β^-) (2017Wa10)

Q-value: S(2n)=11559 7, S(2p)=10433 12 (2017Wa10)

E(level) (keV)	XREF	J^π(level)	T_1/2(level)	E(γ) (keV)	I(γ)	M(γ)	Final Levels
0.0	B C	0+	157.1 m 13 % α = 8.1 3 % SF = 91.9 3
48.12 16	B C	2+		48.3 3 S		[E2]	0.0	0+
159.60 20	B C	4+		111.6 2	100	[E2]	48.12	2+
332.2 3	B	6+		172.6 2	100	[E2]	159.60	4+
563.3 3	B	8+		231.1 2	100	[E2]	332.2	6+
682.21 14	B C	(2+)		634.1 2 682.2 2	94 10 100		48.12 0.0	2+ 0+
725.43 19	B C	(3+)		565.9 3 677.4 2	23 4 100 8		159.60 48.12	4+ 2+
783.20 22	B	(4+)		450.8 15 623.5 2	13 100		332.2 159.60	6+ 4+
853.4 5	B	(5+)		693.8 15	100		159.60	4+
881.59 19	B	(2-)		156 2 199.3 2 833.5 2	1.5 26 100		725.43 682.21 48.12	(3+) (2+) 2+
922.03 23	B	(3-)		141 2 197.4 5 ? 762.7 2	4 35 100		783.20 725.43 159.60	(4+) (3+) 4+
938.8 16	B	(6+)		606.6 15	100		332.2	6+
978.1 5	B	(4-)		252.7 5	100		725.43	(3+)
1039.0 4	B	(7+)		185.7 5 706.8 2	22 100		853.4 332.2	(5+) 6+
1045.1 5	B	(5-)		67.0S 192 2			978.1 853.4	(4-) (5+)
1099.73 18	B	(3+)		178.0 2 218.1 2 316.4 2 374.2 2 417.6 2 940.1 15 1051.5 2	≤19 100 18 25 27 14 45		922.03 881.59 783.20 725.43 682.21 159.60 48.12	(3-) (2-) (4+) (3+) (2+) 4+ 2+
E(level) (keV)	XREF	J^π(level)	T_1/2(level)	E(γ) (keV)	I(γ)	M(γ)	Final Levels
1123.0 5	B	(6-)		78.0S 269.5 5			1045.1 853.4	(5-) (5+)
1150.3?	B	(8+)		211.2 5 ? 586.6 15 ?			938.8 563.3	(6+) 8+
1150.4 4	B	(4+)		50.8S			1099.73	(3+)
1213.5 11 ?	B	(7-)		90.5S			1123.0	(6-)
1251.6 4	B	(5+)		397.2 5 ? 468.4 5 526.1 5	82 100 91		853.4 783.20 725.43	(5+) (4+) (3+)
1326.17 18	C	(1+)		600.8 4 644.0 2 1278.0 3 1326.1 3	17 3 100 8 14 2 33 3		725.43 682.21 48.12 0.0	(3+) (2+) 2+ 0+
1328.3 4 ?	B	(6+)		76.8S 178.0 2			1251.6 1150.4	(5+) (4+)
1360.4 3	C	(2+)		634.1 2 ? 677.3 2 ? 1200.6 5 1312.3 3	76 30 42 9 100 9		725.43 682.21 159.60 48.12	(3+) (2+) 4+ 2+
1374.19 18	C	(1-)		692.0 2 1326.1 3 1374.1 3	100 8 49 4 52 6		682.21 48.12 0.0	(2+) 2+ 0+
1405.27 21	C	(2-)		680.0 3 723.0 2 1357.1 3	70 6 82 9 100 9		725.43 682.21 48.12	(3+) (2+) 2+
1425.1 3	B	(7-)	70 ns 5 % IT = 100	96.8 2 211.2 5 ? 275.3 2 ? 302.0 5 380.0 5 861.8 2 1092.9 2	13 ≤4.4 5.8 4.2 1.9 100 47		1328.3 1213.5 1150.3 1123.0 1045.1 563.3 332.2	(6+) (7-) (8+) (6-) (5-) 8+ 6+
E(level) (keV)	XREF	J^π(level)	T_1/2(level)	E(γ) (keV)	I(γ)	M(γ)	Final Levels
1559.8 4	B	(7+,8+)		134.7 2	100	[E1]	1425.1	(7-)

E(level): From least-squares fit to Eγ values

E(level) (keV)	J^π(level)	T_1/2(level)	E(γ)	I(γ)	M(γ)	Final Levels
Band 1 - Kπ=0⁺ band.
0.0	0+	157.1 m 13 % α = 8.1 3 % SF = 91.9 3
48.12 16	2+		48.3 3 S		[E2]	0.0	0+
159.60 20	4+		111.6 2	100	[E2]	48.12	2+
332.2 3	6+		172.6 2	100	[E2]	159.60	4+
563.3 3	8+		231.1 2	100	[E2]	332.2	6+
E(level) (keV)	J^π(level)	T_1/2(level)	E(γ)	I(γ)	M(γ)	Final Levels
Band 2 - Kπ=(2⁺) γ-vibrational band.
682.21 14	(2+)
725.43 19	(3+)		565.9 3 677.4 2	23 4 100 8		159.60 48.12	4+ 2+
783.20 22	(4+)		450.8 15 623.5 2	13 100		332.2 159.60	6+ 4+
853.4 5	(5+)		693.8 15	100		159.60	4+
938.8 16	(6+)		606.6 15	100		332.2	6+
1039.0 4	(7+)		185.7 5 706.8 2	22 100		853.4 332.2	(5+) 6+
1150.3	(8+)		211.2 5 ? 586.6 15 ?			938.8 563.3	(6+) 8+
E(level) (keV)	J^π(level)	T_1/2(level)	E(γ)	I(γ)	M(γ)	Final Levels
Band 3 - Kπ=(2-) octupole-vibrational band.
881.59 19	(2-)
922.03 23	(3-)		141 2 197.4 5 ? 762.7 2	4 35 100		783.20 725.43 159.60	(4+) (3+) 4+
978.1 5	(4-)		252.7 5	100		725.43	(3+)
1045.1 5	(5-)		67.0S 192 2			978.1 853.4	(4-) (5+)
1123.0 5	(6-)		78.0S 269.5 5			1045.1 853.4	(5-) (5+)
1213.5 11	(7-)		90.5S			1123.0	(6-)
E(level) (keV)	J^π(level)	T_1/2(level)	E(γ)	I(γ)	M(γ)	Final Levels
Band 4 - Kπ=(3⁺) band
1099.73 18	(3+)
1150.4 4	(4+)		50.8S			1099.73	(3+)
E(level) (keV)	J^π(level)	T_1/2(level)	E(γ)	I(γ)	M(γ)	Final Levels
Band 5 - Kπ=(5⁺) band
1251.6 4	(5+)
1328.3 4	(6+)		76.8S 178.0 2			1251.6 1150.4	(5+) (4+)

E(level) (keV)	J^π(level)	T_1/2(level)	E(γ) (keV)	Multipolarity	Conversion Coefficient	Additional Data
48.12	2+		48.3 3	[E2]	832	α=832
159.60	4+		111.6 2	[E2]	15.96	α=15.96
332.2	6+		172.6 2	[E2]	2.40	α=2.40
563.3	8+		231.1 2	[E2]	0.772	α=0.772
1559.8	(7+,8+)		134.7 2	[E1]	0.0735	α=0.0735

E(level)	J^π(level)	T_1/2(level)	Comments
0.0	0+	157.1 m 13 % α = 8.1 3 % SF = 91.9 3	Branching: α/(α+SF)=0.081 3 was determined by 1968Ho13 from α and SF counts. Other measurement: SF/α=35 10 (1965Si14). E(level): Branching: α/(α+SF)=0.081 3 was determined by 1968Ho13 from α and SF counts. Other measurement: SF/α=35 10 (1965Si14). Kπ=0⁺ band.
48.12	2+		E(level): Kπ=0⁺ band. J^π(level): Strong evidence for the presence of rotational band based on g.s.
159.60	4+		E(level): Kπ=0⁺ band. J^π(level): Strong evidence for the presence of rotational band based on g.s.
332.2	6+		E(level): Kπ=0⁺ band. J^π(level): Strong evidence for the presence of rotational band based on g.s.
563.3	8+		E(level): Kπ=0⁺ band. J^π(level): Strong evidence for the presence of rotational band based on g.s.
682.21	(2+)		E(level): Kπ=(2⁺) γ-vibrational band.
725.43	(3+)		E(level): Kπ=(2⁺) γ-vibrational band.
783.20	(4+)		E(level): Kπ=(2⁺) γ-vibrational band.
853.4	(5+)		E(level): Kπ=(2⁺) γ-vibrational band.
881.59	(2-)		E(level): Kπ=(2-) octupole-vibrational band.
922.03	(3-)		E(level): Kπ=(2-) octupole-vibrational band.
938.8	(6+)		E(level): Kπ=(2⁺) γ-vibrational band.
978.1	(4-)		E(level): Kπ=(2-) octupole-vibrational band.
1039.0	(7+)		E(level): Kπ=(2⁺) γ-vibrational band.
1045.1	(5-)		E(level): Kπ=(2-) octupole-vibrational band.
1099.73	(3+)		E(level): Kπ=(3⁺) band.
1123.0	(6-)		E(level): Kπ=(2-) octupole-vibrational band.
1150.3	(8+)		E(level): Kπ=(2⁺) γ-vibrational band.
1150.4	(4+)		E(level): Kπ=(3⁺) band.
1213.5	(7-)		E(level): Kπ=(2-) octupole-vibrational band.
1251.6	(5+)		E(level): Kπ=(5⁺) band.
1326.17	(1+)		Proposed configuration=ν7/2[613]~#ν9/2[615] (2000Ah02).
1328.3	(6+)		E(level): Kπ=(5⁺) band.
1360.4	(2+)		Proposed configuration=ν7/2[613]~#ν9/2[615] (2000Ah02).
1374.19	(1-)		Proposed configuration=π7/2[633]~#π7/2[514] (2000Ah02).
E(level)	J^π(level)	T_1/2(level)	Comments
1405.27	(2-)		Proposed configuration=π7/2[633]~#π7/2[514] (2000Ah02).
1425.1	(7-)	70 ns 5 % IT = 100	The partial half-life for fission was deduced by 1989Ha10 as 0.8 ms +88-7 from the β-delayed-fission probability of 2×10^-5 (measured number of delayed fissions/total number of β^- decays of 7.⁶H ²⁵⁶Es; two fission events were observed.).