List of levels for 26SI

Authors: M.S. Basunia and A.M. Hurst | Citation: Nucl. Data Sheets 134, 1 (2016) | Cutoff date: 1-Feb-2016

E(level): Up to 5929.4 - from a least-squares fit to γ-ray energies, except for 3842.2-, 5229-, and 5913.8-keV levels. 1763.5γ from 5517.79-keV level poorly fit to the level scheme and omitted during the fitting procedure and also uncertainty tripled for 988.9γ from 2787 keV level.

J^π(level): Taken from 2004Pa42 except where noted. Assignments established by comparison of measured differential cross sections with Hauser-Feshbach calculations.

T_1/2(level): From (³He,nγ), deduced using the Doppler-shift attenuation method except where noted; widths deduced from R-matrix fits to differential cross-sections for ¹H(²⁵Al,p) measured in 2014Ju02 except where noted.

E(γ): Weighted average of data from 2007Se02 (¹⁶O,2nγ), and 2015Do07, 2014Ko41 both in (³He,nγ), except where noted. Uncertainty from the most precise measurement.

I(γ): From 2015Do07 (³He,nγ), except where noted.

M(γ): Inferred from deduced anisotropy coefficients for the angular distributions measured in the fusion-evaporation reaction ¹²C(¹⁶O,2nγ) from 2007Se02, except where noted or from γ(θ) measurements in 2015Do07 (³He,nγ).

E(level) (keV)	J^π(level)	T_1/2(level)	E(γ) (keV)	Multipolarity	Mixing Ratio	Additional Data
1797.30	2+	440 fs 40	1797.2 1	E2		B(E2)(W.u.)=15.3 15
2787.05	2+	146 fs 35	988.9 1	M1+E2	+0.21 10	B(E2)(W.u.)=25 24, B(M1)(W.u.)=0.100 25
2787.05	2+	146 fs 35	2787.0 2	E2		B(E2)(W.u.)=1.7 4
3336.35	0+	1.52 ps 48	1539.0 2	E2		B(E2)(W.u.)=10 5
4139.06	2+	35 fs 3	4141 3	[E2]		B(E2)(W.u.)=0.28 15
4446.37	(4+)	< 350 fs	2648.7 2	(E2)		B(E2)(W.u.)>2.3

Q(β-)=-18110 keV SY	S(n)= 19040 keV 10	S(p)= 5513.8 keV 5	Q(α)= -9166.0 keV 3
Reference: 2012WA38

References:
A	²⁶P ε decay	B	²⁷S β⁺p decay
C	¹H(²⁵Al,p)	D	¹H(²⁷Si,²⁶SiG)
E	¹²C(¹⁶O,2nγ)	F	²⁴Mg(³He,n)
G	²⁴Mg(³He,nγ)	H	Coulomb Excitation
I	²⁸Si(p,p2nγ)	J	²⁸Si(p,t)
K	²⁸Si(⁴He,⁶He)	L	²⁹Si(³He,⁶He)

E(level) (keV)	XREF	J^π(level)	T_1/2(level)	E(γ) (keV)	I(γ)	M(γ)	Final Levels
0.0	A D E F G H J L	0+	2.2453 s 7 % ε = 100
1797.30 10	A B D E F G H J K L	2+	440 fs 40	1797.2 1	100	E2	0.0	0+
2787.05 13	A D E F G J K L	2+	146 fs 35	988.9 1 2787.0 2	100.0 27 48.9 27	M1+E2 E2	1797.30 0.0	2+ 0+
3336.35 22	D E F G J K	0+	1.52 ps 48	549.3 1539.0 2	<2 100 19	E2	2787.05 1797.30	2+ 2+
3757.56 15	A D E F G J	(3+)	< 485 fs	970.5 1 1960.1 2	82 4 100 4	(M1+E2) (M1+E2)	2787.05 1797.30	2+ 2+
3842.2 18	A G	(4+)		1055.1 2044.8	<15 100 28		2787.05 1797.30	2+ 2+
4139.06 20	A D E F G J K L	2+	35 fs 3	802.7 1351.5 4 2341.8 2 4141 3	<12 4.9 8 100.0 21 11.8 59	M1+E2 [E2]	3336.35 2787.05 1797.30 0.0	0+ 2+ 2+ 0+
4187.77 19	A D E F G J L	(3+)		1400.5 2 2390.3 3	100.0 59 57.4 59	D D	2787.05 1797.30	2+ 2+
4446.37 18	D E F G J K L	(4+)	< 350 fs	1658.3 14 2648.7 2	10 5 100.0 22	(E2)	2787.05 1797.30	2+ 2+
4796.9 8	D E G J	(4+)		2999.4 8	100	Q	1797.30	2+
4811.0 10	D E F G J K L	(2+)	< 69 fs	2023.9 10 4810.5	100 12 <10	D+Q	2787.05 0.0	2+ 0+
4831.2 4	E G J	(0+)		2044.1 3	100		2787.05	2+
5147.5 8	D E F G J K L	2+		2359.3 15 3350.3 8	100 4 19 5	D	2787.05 1797.30	2+ 2+
5229 12 ?	J	(2+)
5289.04 18	D E F G J K L	4+		842.2 2 1530.1 10 2501.9 10 3492.0 2	53 7 100 7 8 9 43 9	D+Q D Q	4446.37 3757.56 2787.05 1797.30	(4+) (3+) 2+ 2+
E(level) (keV)	XREF	J^π(level)	T_1/2(level)	E(γ) (keV)	I(γ)	M(γ)	Final Levels
5517.79 23	D E F G J K L	(4+)		1071.6 2 1329.5 3 1763.5 8 2733 3	65 11 95 11 100 11 11 14	D D	4446.37 4187.77 3757.56 2787.05	(4+) (3+) (3+) 2+
5676.2 3	D E F G J L	1+		2888.9 9 3878.6 3	16 7 100 5	D	2787.05 1797.30	2+ 2+
5890.1 3	G K	0+		1751.9 10 3103.1 4 4092.1 4	76 14 95 14 100 14	Q Q	4139.06 2787.05 1797.30	2+ 2+ 2+
5929.4 8	A F J K	3+		1741.6 7	100		4187.77	(3+)
5945.9 40	F J L	(0+)
6101	K
6295.3 24	A C F J K	2+
6382.7 29	A C F J K	(2+)
6461.1 28	C F J	0+
6765 5	A
6787 4	C F J K	3-
6810 8	K
6880 30	C F	(0+)
7018 6	C J K	(3+)
7154 4	C F J K	2+	2.7 keV 1
7198 6	J K	(5+)
7418.4 23	C F J K	(4+)	1.1 keV 1
7496.4 40	A C F J K	2+	15.9 keV 3
7522 12	J	(5-)
7606 6	A
7674.2 40	C J K	(2+)	30.1 keV 5
7701.1 30	C F J K	(3-)	41 keV 6
7886.2 40	C F J K	(1-)	22.8 keV 13
7921 3	K
E(level) (keV)	XREF	J^π(level)	T_1/2(level)	E(γ) (keV)	I(γ)	M(γ)	Final Levels
7962 5	A
8008 14	C	(3+)	4.5 keV 3
8144 21	A C F	(1-,2+)
8222 5	J	(1-)
8254 5	A
8269 4	J	(2+)
8282 6	K
8356 12	C	(3+)	27 keV 8
8431 6	K
8558 17	A F J K	(2+)
8689 21	F J	(1-,2+)
8806 5	K
8952 7	K
8989 7	J	(4+)
9067 5	K
9124 8 ?	J
9170 30	F	(1-,2+)
9247 8	K
9316 5	J	(4+)
9373.3 7	A K
9433 4	A
9606.1 9	J K	(2+)
9725 7	A
9762 4	J	(5-)
9802 7	K
9910.2 20	J K	(0+)
10070 8	K
10296.9 60	A K
10405 5	A J
10688 9	A J
E(level) (keV)	XREF	J^π(level)	T_1/2(level)	E(γ) (keV)	I(γ)	M(γ)	Final Levels
10827 8	A J
13015 4	A	(3+)

E(level)	J^π(level)	T_1/2(level)	Comments
1797.30	2+	440 fs 40	J^π(level): Deduced from comparison between measured angular distributions and DWBA calculations in 1982Bo14.
2787.05	2+	146 fs 35	J^π(level): Deduced from comparison between measured angular distributions and DWBA calculations in 1982Bo14.
3336.35	0+	1.52 ps 48	J^π(level): Deduced from comparison between measured angular distributions and DWBA calculations in 1982Bo14.
4187.77	(3+)		XREF: L(4211).
4446.37	(4+)	< 350 fs	J^π(level): Conflicting spin-parity assignments. See comments.
5676.2	1+		Γ_γ=1.2×10^-4 keV (2009Pe04); other value; Γ_p=1.3×10^-12 keV; Γ_γ=1.1×10^-4 keV (2006Ba65). E(level): Γ_γ=1.2×10^-4 keV (2009Pe04); other value; Γ_p=1.3×10^-12 keV; Γ_γ=1.1×10^-4 keV (2006Ba65).
5929.4	3+		XREF: F(5912)K(5918). E(level): α value of 5926.9 keV 6 may be obtained from the weighted average of 5927 keV 4 (2010Ch44), 5921 keV {12 (2010Ma43), 5912 keV 4 (2004Pa42), 5916 keV 2 (2002Ba25), 5928.7 keV 7 (2013Be41), 5929 keV 5 (2004Th09), and 5918 keV 8 (2008Kw01). Other values not used in averaging: 5914 keV 2 (200Ba25) and 5914 keV 4 (2009Pe04) for reasons outlined in Sect. IV of 2016Ch09, and 5910 keV 30 (1982Bo14) owing to its large uncertainty overlapping with neighboring resonances. Both the adopted and weighted values are statistically consistent with the suggested value of 5927.6 keV 10 reported in the reanalysis of 2016Ch09. J^π(level): Conflicting spin-parity assignments. See comments.
5945.9	(0+)		Γ_γ=5.7×10^-6 keV (2009Pe04); other value; Γ_p=1.9×10^-5 keV; Γ_γ=8.8×10^-6 keV (2006Ba65). E(level): Γ_γ=5.7×10^-6 keV (2009Pe04); other value; Γ_p=1.9×10^-5 keV; Γ_γ=8.8×10^-6 keV (2006Ba65). The existence of this level as a separate resonance is called into question in 2015Do07 due to lack of evidence in their (³He,nγ) measurement and also argue that 5946 keV level might the same level as that at 5929.4 keV. This inference is refuted in 2016Ch09 on the basis of (³He,nγ) (2004Pa42) and (p,t) (2010Ma43) measurements that have populated both this resonance and the 5929.4-keV resonance simultaneously. J^π(level): Conflicting spin-parity assignments. See comments. 2002Ca24 argue for a 3⁺ assignment in (³He,⁶He) on the basis that other 0⁺ states are only weakly populated in their measurement. However, 2002Ca24 note "a small high energy shoulder on the peak, making it slightly wider at the base, suggests that another state lies there. " Evaluators note: It appears that the reported peak at 5945 keV 8 in 2002Ca24 is a doublet of 5929⁺5946 and the 3⁺ assignment probably related to the 5929 keV state. 2016Ch09 suggest a similar view for this spin-parity assignment. However, from recent measurements, 2015Do07 (³He,nγ) propose the first 0⁺ state above proton separation energy at 5890 keV and note that there is no theoretical prediction or experimental evidence for t=1 states in analogue nuclei ²⁶Al and ²⁶Mg for two closely spaced 0⁺ states in this region and the existence of this level as a separate resonance is called into question. However, 2016Ch09 argued that both this level and the 5890.1-keV level may have 0⁺ assignments due to particle excitations into a different shell and suggest for additional experimental and theoretical work.
6295.3	2+		Γ_p/(Γ_p+Γ_γ)=0.88 20 determined from 6300⁺6380-keV doublet peak in 2010Ch44. E(level): Γ_p/(Γ_p+Γ_γ)=0.88 20 determined from 6300⁺6380-keV doublet peak in 2010Ch44.
6382.7	(2+)		Γ_p/(Γ_p+Γ_γ)=0.88 20 determined from 6300⁺6380-keV doublet peak in 2010Ch44. E(level): Γ_p/(Γ_p+Γ_γ)=0.88 20 determined from 6300⁺6380-keV doublet peak in 2010Ch44.
6787	3-		Γ_p/(Γ_p+Γ_γ)=1.21 24 (2010Ch44). E(level): Γ_p/(Γ_p+Γ_γ)=1.21 24 (2010Ch44).
6880	(0+)		J^π(level): Conflicting spin-parity assignments. See comments.
7018	(3+)		Γ_p/(Γ_p+Γ_γ)=1.04 25 (2010Ch44). E(level): Γ_p/(Γ_p+Γ_γ)=1.04 25 (2010Ch44). J^π(level): Deduced from mirror assignments with ²⁶Mg presented in Fig. 7 in 2010Ma43.
7154	2+	2.7 keV 1	Γ_p/(Γ_p+Γ_γ)=1.04 25 (2010Ch44). E(level): Γ_p/(Γ_p+Γ_γ)=1.04 25 (2010Ch44).
7198	(5+)		J^π(level): Deduced from mirror assignments with ²⁶Mg presented in Fig. 7 in 2010Ma43.
7418.4	(4+)	1.1 keV 1	Γ_p/(Γ_p+Γ_γ)=1.31 27 determined from 7425⁺7498-keV doublet peak in 2010Ch44. E(level): Γ_p/(Γ_p+Γ_γ)=1.31 27 determined from 7425⁺7498-keV doublet peak in 2010Ch44. J^π(level): Conflicting spin-parity assignments. See comments.
7496.4	2+	15.9 keV 3	Γ_p/(Γ_p+Γ_γ)=1.31 27 determined from 7425⁺7498-keV doublet peak in 2010Ch44. E(level): Γ_p/(Γ_p+Γ_γ)=1.31 27 determined from 7425⁺7498-keV doublet peak in 2010Ch44.
7522	(5-)		J^π(level): Deduced from mirror assignments with ²⁶Mg presented in Fig. 7 in 2010Ma43.
7674.2	(2+)	30.1 keV 5	J^π(level): Deduced from mirror assignments with ²⁶Mg presented in Fig. 7 in 2010Ma43.
7701.1	(3-)	41 keV 6	Γ_p/(Γ_p+Γ_γ)=1.18 23 (2010Ch44). E(level): Γ_p/(Γ_p+Γ_γ)=1.18 23 (2010Ch44). J^π(level): Deduced from mirror assignments with ²⁶Mg presented in Fig. 7 in 2010Ma43. T_1/2(level): Width deduced from R-matrix fits to differential cross-sections for ¹H(²⁵Al,p) measured in 2012Ch04.
7886.2	(1-)	22.8 keV 13	Γ_p/(Γ_p+Γ_γ)=1.11 22 (2010Ch44). E(level): Γ_p/(Γ_p+Γ_γ)=1.11 22 (2010Ch44). J^π(level): Deduced from mirror assignments with ²⁶Mg presented in Fig. 7 in 2010Ma43.
8144	(1-,2+)		J^π(level): Based on comparison of measured angular distributions with DWBA calculations in 1982Bo14.
8222	(1-)		J^π(level): Deduced from mirror assignments with ²⁶Mg presented in Fig. 7 in 2010Ma43.
8269	(2+)		J^π(level): Deduced from mirror assignments with ²⁶Mg presented in Fig. 7 in 2010Ma43.
8558	(2+)		J^π(level): Deduced from mirror assignments with ²⁶Mg presented in Fig. 7 in 2010Ma43.
E(level)	J^π(level)	T_1/2(level)	Comments
8689	(1-,2+)		J^π(level): Based on comparison of measured angular distributions with DWBA calculations in 1982Bo14.
8989	(4+)		J^π(level): Deduced from mirror assignments with ²⁶Mg presented in Fig. 7 in 2010Ma43.
9170	(1-,2+)		J^π(level): Based on comparison of measured angular distributions with DWBA calculations in 1982Bo14.
9316	(4+)		J^π(level): Based on mirror assignments with ²⁶Mg described in 1986Al06 and 2011Ma46.
9606.1	(2+)		J^π(level): Based on mirror assignments with ²⁶Mg described in 1986Al06 and 2011Ma46.
9762	(5-)		J^π(level): Based on mirror assignments with ²⁶Mg described in 1986Al06 and 2011Ma46.
9910.2	(0+)		J^π(level): Based on mirror assignments with ²⁶Mg described in 1986Al06 and 2011Ma46.
10405			XREF: J(10436).
10688			XREF: J(10660).
10827			XREF: J(11010).

E(level)	E(gamma)	Comments
1797.30	1797.2	M(γ): Deduced from measured a₂/a₄ anisotropy coefficients from 1797.2γ to g.s. (2007Se02).
2787.05	988.9	I(γ): From 2007Se02 (¹⁶O,2nγ)
2787.05	2787.0	I(γ): Others: 67 5 (2015Do07) and 1.35 20 (2014Ko41) both in (³He,nγ).. From 2007Se02 (¹⁶O,2nγ)
3336.35	549.3	E(γ): From level energy differences, recoil energy subtracted. Placement in 1969Be31 (³He,nγ). I(γ): Limits are proposed in Table 4 of 1969Be31, corresponding to the Doppler-shift attenuation measurement (DSAM) for ²⁴Mg(³He,nγ). M(γ): From measured gamma-transition widths deduced using Doppler-shift attenuation method for ²⁴Mg(³He,nγ) in 1969Be31.
3336.35	1539.0	M(γ): From measured gamma-transition widths deduced using Doppler-shift attenuation method for ²⁴Mg(³He,nγ) in 1969Be31.
3757.56	970.5	I(γ): Others: 47 4 (2014Ko41) and 43 14 (1969Be31) both in (³He,nγ). M(γ): From (³He,nγ) - 1969Be31.
3757.56	1960.1	M(γ): From (³He,nγ) - 1969Be31.
3842.2	1055.1	E(γ): From level energy differences, recoil energy subtracted. Placement in 1969Be31 (³He,nγ). I(γ): Limits are proposed in Table 4 of 1969Be31, corresponding to the Doppler-shift attenuation measurement (DSAM) for ²⁴Mg(³He,nγ). M(γ): From measured gamma-transition widths deduced using Doppler-shift attenuation method for ²⁴Mg(³He,nγ) in 1969Be31.
3842.2	2044.8	E(γ): Measured in γ-γ coincidence (1969Be31).. From level energy differences, recoil energy subtracted. Placement in 1969Be31 (³He,nγ). I(γ): Limits are proposed in Table 4 of 1969Be31, corresponding to the Doppler-shift attenuation measurement (DSAM) for ²⁴Mg(³He,nγ).
4139.06	802.7	E(γ): From level energy differences, recoil energy subtracted. Placement in 1969Be31 (³He,nγ). I(γ): Limits are proposed in Table 4 of 1969Be31, corresponding to the Doppler-shift attenuation measurement (DSAM) for ²⁴Mg(³He,nγ).
	1351.5	I(γ): From 2014Ko41. Other: 11 5 (2015Do07) both in (³He,nγ). Limits are proposed in Table 4 of 1969Be31, corresponding to the Doppler-shift attenuation measurement (DSAM) for ²⁴Mg(³He,nγ).
	2341.8	I(γ): From 2014Ko41. Other: 100 4 (2015Do07) both in (³He,nγ) M(γ): In (³He,nγ), assigned by evaluators based on γ(θ) data in 2015Do07 and RUL (if applicable).
	4141	E(γ): From 2007Se02 (¹⁶O,2nγ) I(γ): From 2007Se02 (¹⁶O,2nγ). Other: 25 13 (1969Be31) in (³He,nγ).
4187.77	1400.5	I(γ): From 2007Se02 (¹⁶O,2nγ). Other: 61 5 (2015Do07) (³He,nγ). Evaluators adopt as the strongest branch along with supporting evidence in 2014Ko41 (³He,nγ).
4187.77	2390.3	I(γ): From 2007Se02 (¹⁶O,2nγ). Other: 100 5 (2015Do07) (³He,nγ). Evaluators adopt this as a weaker branch along with supporting evidence in 2014Ko41 (³He,nγ).
4446.37	1658.3	E(γ): From 2015Do07 (³He,nγ)
4796.9	2999.4	E(γ): Average of data from 2007Se02 (¹⁶O,2nγ), and 2015Do07, 2014Ko41 both in (³He,nγ) M(γ): In (³He,nγ), assigned by evaluators based on γ(θ) data in 2015Do07 and RUL (if applicable).
4811.0	2023.9	E(γ): Average of data from 2007Se02 (¹⁶O,2nγ), and 2015Do07, 2014Ko41 both in (³He,nγ) M(γ): In (³He,nγ), assigned by evaluators based on γ(θ) data in 2015Do07 and RUL (if applicable).
4811.0	4810.5	E(γ): From level energy differences, recoil energy subtracted. Placement in 1969Be31 (³He,nγ). I(γ): Limits are proposed in Table 4 of 1969Be31, corresponding to the Doppler-shift attenuation measurement (DSAM) for ²⁴Mg(³He,nγ).
5147.5	2359.3	E(γ): From 2015Do07 (³He,nγ) M(γ): In (³He,nγ), assigned by evaluators based on γ(θ) data in 2015Do07 and RUL (if applicable).
5147.5	3350.3	E(γ): From 2015Do07 (³He,nγ)
5289.04	842.2	M(γ): In (³He,nγ), assigned by evaluators based on γ(θ) data in 2015Do07 and RUL (if applicable).
	1530.1	E(γ): Average of data from 2007Se02 (¹⁶O,2nγ), and 2015Do07, 2014Ko41 both in (³He,nγ) M(γ): In (³He,nγ), assigned by evaluators based on γ(θ) data in 2015Do07 and RUL (if applicable).
	2501.9	E(γ): From 2015Do07 (³He,nγ)
	3492.0	E(γ): From 2015Do07 (³He,nγ) M(γ): In (³He,nγ), assigned by evaluators based on γ(θ) data in 2015Do07 and RUL (if applicable).
E(level)	E(gamma)	Comments
5517.79	1329.5	M(γ): In (³He,nγ), assigned by evaluators based on γ(θ) data in 2015Do07 and RUL (if applicable).
	1763.5	E(γ): Average of data from 2007Se02 (¹⁶O,2nγ), and 2015Do07, 2014Ko41 both in (³He,nγ) M(γ): In (³He,nγ), assigned by evaluators based on γ(θ) data in 2015Do07 and RUL (if applicable).
	2733	E(γ): From 2007Se02 (¹⁶O,2nγ). Other: 2736.3 10 (2015Do07) (³He,nγ) - weak transition.
5676.2	2888.9	E(γ): From 2015Do07 (³He,nγ)
5676.2	3878.6	M(γ): In (³He,nγ), assigned by evaluators based on γ(θ) data in 2015Do07 and RUL (if applicable).
5890.1	1751.9	E(γ): From 2015Do07 (³He,nγ)
	3103.1	E(γ): From 2015Do07 (³He,nγ) M(γ): In (³He,nγ), assigned by evaluators based on γ(θ) data in 2015Do07 and RUL (if applicable).
	4092.1	E(γ): a γ at 4094 keV 4 was also observed in 1969Be31 and tentatively assigned to deexcite a level at 4094 keV, with additional weaker γ rays. However, this state was not established in subsequent coincidence measurements in 2007Se02 (¹⁶O,2nγ), 2015Do07 (³He,nγ), and 2014Ko41 (³He,nγ), suggesting it is likely to have been misplaced in 1969Be31.. From 2015Do07 (³He,nγ) M(γ): In (³He,nγ), assigned by evaluators based on γ(θ) data in 2015Do07 and RUL (if applicable).
5929.4	1741.6	E(γ): From ²⁶P ε decay