List of levels for 248BK

Author: C.D. Nesaraja | Citation: Nucl. Data Sheets 204, 374 (2025) | Cutoff date: 30-Jun-2024

Previous evaluator (2014Ma86) has used systematics of hindrance factors and configurations to partly justify Jπ assignments. These arguments are now placed in the documentation record.

Levels: Assignment: ²⁴⁶Cm(α,pn) (1965Mi08).

Gammas: All data are from ²⁵²Es α decay

Q-value: S(2n)=11980 80, S(2p)=11440 50 (syst), Q(ε)=740 50 (2021Wa16)

E(level) (keV)	J^π(level)	T_1/2(level)	E(γ) (keV)	Multipolarity	Mixing Ratio	Conversion Coefficient	Additional Data
70.64	(7+)		70.65 5	M1+E2	3.4 21	98	α=98 24, α(L)=71 17, α(M)=20 5, α(N)=5.6 14, α(O)=1.37 35, α(P)=0.23 5, α(Q)=1.0×10^-3 9
135.06	(8-)		64.42 5	[E1]		0.450	α=0.450 6, α(L)=0.336 5, α(M)=0.0843 12, α(N)=0.02294 32, α(O)=0.00559 8, α(P)=0.000920 13, α(Q)=3.14×10^-5 4
151.32	(8+)		80.7 1	M1+E2	1.3 +25-6	40	α=40 13, α(L)=29 9, α(M)=8.1 27, α(N)=2.3 8, α(O)=0.56 18, α(P)=0.095 28, α(Q)=0.0013 7
151.32	(8+)		151.3 1	[E2]		3.26	α=3.26 5, α(K)=0.1614 23, α(L)=2.235 32, α(M)=0.633 9, α(N)=0.1770 25, α(O)=0.0435 6, α(P)=0.00732 10, α(Q)=4.63×10^-5 7
373.0			193.5 1	M1		5.33	α=5.33 7, α(K)=4.17 6, α(L)=0.869 12, α(M)=0.2130 30, α(N)=0.0587 8, α(O)=0.01512 21, α(P)=0.00298 4, α(Q)=0.0002092 29
373.0			228.0 4	M1		3.36	α=3.36 5, α(K)=2.63 4, α(L)=0.547 8, α(M)=0.1339 20, α(N)=0.0369 5, α(O)=0.00950 14, α(P)=0.001876 28, α(Q)=0.0001313 20
399.7	(5+)		399.7 3	M1		0.709	α=0.709 10, α(K)=0.556 8, α(L)=0.1145 16, α(M)=0.0280 4, α(N)=0.00772 11, α(O)=0.001987 28, α(P)=0.000392 6, α(Q)=2.74×10^-5 4
590.0	(4+)		377.4 3	M1		0.830	α=0.830 12, α(K)=0.651 9, α(L)=0.1341 19, α(M)=0.0328 5, α(N)=0.00905 13, α(O)=0.002328 33, α(P)=0.000459 7, α(Q)=3.21×10^-5 5
590.0	(4+)		418.5 3	M1		0.625	α=0.625 9, α(K)=0.491 7, α(L)=0.1009 14, α(M)=0.02468 35, α(N)=0.00680 10, α(O)=0.001751 25, α(P)=0.000345 5, α(Q)=2.413×10^-5 34

Q(β-)=890 keV 50	S(n)= 5430 keV 50	S(p)= 4690 keV 50	Q(α)= 5830 keV 50
Reference: 2021WA16

E(level) (keV)	XREF	J^π(level)	T_1/2(level)	E(γ) (keV)	I(γ)	M(γ)	Final Levels
0.0	A	(6+)	> 9 y % ε = ? % α = ?
0.0+X		1(-)	23.7 h 2 % β^- = 70 5 % ε = 30 5
70.64 5	A	(7+)		70.65 5	100	M1+E2	0.0	(6+)
135.06 7	A	(8-)		64.42 5	100	[E1]	70.64	(7+)
145 3	A
151.32 8	A	(8+)		80.7 1 151.3 1	44 7 100 9	M1+E2 [E2]	70.64 0.0	(7+) (6+)
171.5 8	A	(3+,4+,5+)
179.5 4	A
212.6 8	A	(3+,4+,5+)
262 6	A
339 6	A
373.0 4	A			193.5 1 228.0 4	100 12 53 9	M1 M1	179.5 145
399.7 3	A	(5+)		399.7 3		M1	0.0	(6+)
424 6	A
458 6	A
483 6	A
529.1 7	A			529.1 7			0.0	(6+)
590.0 7	A	(4+)		377.4 3 418.5 3 590.0 7	55 7 100 10 38 3	M1 M1	212.6 171.5 0.0	(3+,4+,5+) (3+,4+,5+) (6+)
624 5	A	(7+)
657 5	A
700 5	A	(8+)

E(level) (keV)	J^π(level)	T_1/2(level)	E(γ)	I(γ)	M(γ)	Final Levels
Band 1 - K^π=6⁺, π3/2[521]~#ν9/2[734] band
0.0	(6+)	> 9 y % ε = ? % α = ?
70.64 5	(7+)
151.32 8	(8+)		80.7 1 151.3 1	44 7 100 9	M1+E2 [E2]	70.64 0.0	(7+) (6+)
E(level) (keV)	J^π(level)	T_1/2(level)	E(γ)	I(γ)	M(γ)	Final Levels
Band 2 - K^π=7⁺, π7/2[633]~#ν7/2[613] band
624 5	(7+)
700 5	(8+)

E(level)	J^π(level)	T_1/2(level)	Comments
0.0	(6+)	> 9 y % ε = ? % α = ?	E(level): K^π=6⁺, π3/2[521]~#ν9/2[734] band.
0.0+X	1(-)	23.7 h 2 % β^- = 70 5 % ε = 30 5	The ratio of ε decay/β^- decay was determined by 1978Gr10 from measured I(Curium K\| x ray from ε decay)/I(550.7γ from β^- decay)= 4.25 28 and I(550.7γ)=7.1 5 per 100 β^- decays. E(level): The ratio of ε decay/β^- decay was determined by 1978Gr10 from measured I(Curium K\| x ray from ε decay)/I(550.7γ from β^- decay)= 4.25 28 and I(550.7γ)=7.1 5 per 100 β^- decays.
70.64	(7+)		E(level): K^π=6⁺, π3/2[521]~#ν9/2[734] band.
151.32	(8+)		E(level): K^π=6⁺, π3/2[521]~#ν9/2[734] band.
624	(7+)		E(level): K^π=7⁺, π7/2[633]~#ν7/2[613] band.
700	(8+)		E(level): K^π=7⁺, π7/2[633]~#ν7/2[613] band.