ADOPTED LEVELS, GAMMAS for 31Mg
Authors: Jun Chen and Balraj Singh | Citation: Nucl. Data Sheets 184, 29 (2022) | Cutoff date: 24-Jun-2022
Full ENSDF file | Adopted Levels (PDF version)
| Q(β-)=11829 keV 4 | S(n)= 2312 keV 3 | S(p)= 18886 keV 6 | Q(α)= -12600 keV 90 | ||
| Reference: 2021WA16 |
| References: | |||
| A | 31Na β- decay (17.0 MS) | B | 32Na β-n decay (13.2 MS) |
| C | 33Na β-2n decay (8.0 MS) | D | 2H(30Mg,31MgG) |
| E | 9Be(32Mg,31MgG) | F | 9Be(32Al,31MgG) |
| G | 4He(HI,xγ) | H | Coulomb Excitation |
| E(level) (keV) | XREF | Jπ(level) | T1/2(level) | E(γ) (keV) | I(γ) | M(γ) | Final Levels | |
| 0.0 | ABCDEFGH | 1/2+ | 270 ms 2 % β- = 100 % β-n = 6.2 19 | |||||
| 49.93 6 | ABCDEFGH | 3/2+ | 12.0 ns 4 | 49.9 1 | 100 | [M1] | 0.0 | 1/2+ |
| 220.87 6 | ABCDEFGH | (3/2)- | 133 ps 8 | 171.1 1 220.9 1 | 100 5 35.5 20 | [E1] [E1] | 49.93 0.0 | 3/2+ 1/2+ |
| 460.78 10 | AB EF | (7/2-) | 10.5 ns 8 | 239.9 1 | 100 | [E2] | 220.87 | (3/2)- |
| 673.09 7 | A EF H | 3/2+ | 452.4 2 623.1 1 673.1 1 | 10.8 13 100 6 53 4 | [E1] [M1,E2] [M1,E2] | 220.87 49.93 0.0 | (3/2)- 3/2+ 1/2+ | |
| 941.92 9 | A E G | (1/2-,3/2-) | 892.0 1 941.8 2 | 100 13 88 30 | 49.93 0.0 | 3/2+ 1/2+ | ||
| 944.03 9 | AB EF H | 5/2+ | 723.1 1 894.1 1 | 17.8 33 100 16 | 220.87 49.93 | (3/2)- 3/2+ | ||
| 1028.66 9 | A | (1/2-,3/2-) | 807.8 1 | 100 | 220.87 | (3/2)- | ||
| 1154.0 5 | B EF | (7/2+) | 693.2 5 | 100 | 460.78 | (7/2-) | ||
| 1389.8 10 | B | 929 | 100 | 460.78 | (7/2-) | |||
| 1435.94 8 | A | (1/2-,3/2-) | 1385.9 1 1435.8 2 | 100 11 34 8 | 49.93 0.0 | 3/2+ 1/2+ | ||
| 2015.14 9 | A F | 5/2+ | 1070.9 2 1554.3 1 1794.3 1 1965.0 2 | 14 4 22 3 100 12 8.5 18 | 944.03 460.78 220.87 49.93 | 5/2+ (7/2-) (3/2)- 3/2+ | ||
| 2243.66 6 | A E | 1/2+ | 807.6 1 1215.0 1 1301.7 2 1570.6 2 2022.8 1 2193.6 1 2243.6 1 | 3.0 13 12.1 9 0.69 15 2.0 4 33.8 19 27.4 19 100 6 | 1435.94 1028.66 941.92 673.09 220.87 49.93 0.0 | (1/2-,3/2-) (1/2-,3/2-) (1/2-,3/2-) 3/2+ (3/2)- 3/2+ 1/2+ | ||
E(level): From a least-squares fit to γ-ray energies.
| E(level) (keV) | Jπ(level) | T1/2(level) | E(γ) (keV) | Multipolarity | Conversion Coefficient | Additional Data |
| 49.93 | 3/2+ | 12.0 ns 4 | 49.9 1 | [M1] | 0.01325 | B(M1)(W.u.)=0.0106 21, α=0.01325 20 |
| 220.87 | (3/2)- | 133 ps 8 | 171.1 1 | [E1] | 1.04×10-3 | B(E1)(W.u.)=0.00073 8, α=1.04E-3 2, α(K)=0.000974 14, α(L)=6.25E-5 9, α(M)=2.303E-6 33 |
| (3/2)- | 133 ps 8 | 220.9 1 | [E1] | 0.000465 | B(E1)(W.u.)=0.000139 18, α=0.000465 7, α(K)=0.000436 6, α(L)=2.80E-5 4, α(M)=1.034E-6 15 | |
| 460.78 | (7/2-) | 10.5 ns 8 | 239.9 1 | [E2] | 2.31×10-3 | B(E2)(W.u.)=11.7 9, α=2.31E-3 3 |
| 673.09 | 3/2+ | 623.1 1 | [M1,E2] | B(E2)=0.0024 12 (<a href= "http://www.nndc.bnl.gov/nsr/nsrlink.jsp?2011Se05 ">2011Se05</a>), B(E2)(W.u.)=4.1 20 | ||
| 3/2+ | 673.1 1 | [M1,E2] | B(E2)=0.0011 5 (<a href= "http://www.nndc.bnl.gov/nsr/nsrlink.jsp?2011Se05 ">2011Se05</a>) |
Additional Level Data and Comments:
| E(level) | Jπ(level) | T1/2(level) | Comments |
| 0.0 | 1/2+ | 270 ms 2 % β- = 100 % β-n = 6.2 19 | μ=-0.88340 15 (2008Ko05,2005Ne01,2019StZV) %β-n from 2008ReZZ, 1995ReZZ. Other: %β-n=1.7 3 (1984La03,1984Gu19) is in disagreement. Systematics support higher value of 1995ReZZ. Theoretical values of %β-n=1.0 (2019Mo01) and 0.31, 0.40 (2021Mi17) support the lower value. In the opinion of evaluators, better measurements are needed for %β-n value. E(level): %β-n from 2008ReZZ, 1995ReZZ. Other: %β-n=1.7 3 (1984La03,1984Gu19) is in disagreement. Systematics support higher value of 1995ReZZ. Theoretical values of %β-n=1.0 (2019Mo01) and 0.31, 0.40 (2021Mi17) support the lower value. In the opinion of evaluators, better measurements are needed for %β-n value. Member of Kπ=1/2+, ν1/2[200] sequence (2019Ni04). |
| 49.93 | 3/2+ | 12.0 ns 4 | 3/2+ assignment for this level is indicative of a deformed 2p3h intruder state. In Nilsson configuration this corresponds to a Kπ=3/2+ component from the d3/2 spherical orbit (2007Ki08). E(level): Member of Kπ=1/2+, ν1/2[200] sequence (2019Ni04). |
| 220.87 | (3/2)- | 133 ps 8 | E(level): Member of Kπ=1/2-, ν1/2[330] sequence (2019Ni04). |
| 460.78 | (7/2-) | 10.5 ns 8 | E(level): Member of Kπ=1/2-, ν1/2[330] sequence (2019Ni04). |
| 941.92 | (1/2-,3/2-) | Jπ(level): Assignments proposed by 2019Ni04 in 31Na β- decay, based on high log ft values, and consistency of ratio of intensities of γ rays from each level with Weisskopf estimates for E1 and M1 transitions. However, evaluators notes that no lifetime data are available. | |
| 944.03 | 5/2+ | B(E2)=0.0182 20 (2011Se05) E(level): Member of Kπ=1/2+, ν1/2[200] sequence (2019Ni04). | |
| 1028.66 | (1/2-,3/2-) | Jπ(level): Assignments proposed by 2019Ni04 in 31Na β- decay, based on high log ft values, and consistency of ratio of intensities of γ rays from each level with Weisskopf estimates for E1 and M1 transitions. However, evaluators notes that no lifetime data are available. | |
| 1435.94 | (1/2-,3/2-) | Jπ(level): Assignments proposed by 2019Ni04 in 31Na β- decay, based on high log ft values, and consistency of ratio of intensities of γ rays from each level with Weisskopf estimates for E1 and M1 transitions. However, evaluators notes that no lifetime data are available. |
| E(level) | E(gamma) | Comments |
| 49.93 | 49.9 | E(γ): others: 50.0 5 from 32Na β-n decay and 50.1 2 from 33Na β-2n decay |
| 220.87 | 171.1 | E(γ): weighted average of 170.9 1 from 31Na β- decay, 171.0 5 from 32Na β-n decay, 171.2 1 from 33Na β-2n decay, and 169.6 15 from (HI,xγ) I(γ): from (32Al,31Mgγ). Others: 100 8 (2019Ni04), 100 6 (1993Kl02) and 100 7 (1984Gu19) in 31Na β- decay, 100 22 from 32Na β-n decay, 100 12 from 33Na β-2n decay, and 100 6 from (32Mg,31Mgγ) | 220.9 | E(γ): weighted average of 220.8 1 from 31Na β- decay, 221.0 5 from 32Na β-n decay, 221.0 1 from 33Na β-2n decay, and 221.9 8 from (HI,xγ) I(γ): weighted average of 37.1 25 (2019Ni04), 40.6 32 (1993Kl02), and 44 5 (1984Gu19) in 31Na β- decay, 40 6 from 33Na β-2n decay, 34.0 26 from (32Mg,31Mgγ), and 31.4 20 from (32Al,31Mgγ). Other: 49 10 from 32Na β-n decay |
| 460.78 | 239.9 | E(γ): other: 240.0 5 from 32Na β-n decay |
| 673.09 | 452.4 | E(γ): other: 452.6 6 from (32Al,31Mgγ) I(γ): weighted average of 10.6 13 (2019Ni04) and 12.6 35 (1993Kl02) in 31Na β- decay. Other: 20.6 28 from (32Al,31Mgγ) is discrepant | 623.1 | E(γ): other: 623.3 5 from (32Al,31Mgγ) I(γ): from (32Al,31Mgγ). Others: 100 13 (2019Ni04), 100 8 (1993Kl02) and 100 8 (1984Gu19) in 31Na β- decay | 673.1 | E(γ): other: 673.2 7 from (32Al,31Mgγ) I(γ): unweighted average of 64 4 (2019Ni04), 50 4 (1993Kl02) and 43.5 35 (1984Gu19) in 31Na β- decay, and 53 4 from (32Al,31Mgγ) |
| 941.92 | 892.0 | E(γ): other: 892.7 6 from (HI,xγ) |
| 944.03 | 723.1 | E(γ): other: 724 from Coulomb excitation I(γ): weighted average of 17.0 23 (2019Ni04) from 31Na β- decay and 32 10 from Coulomb excitation | 894.1 | E(γ): others: 894.3 5 from 32Na β-n decay and 894.4 13 from (32Al,31Mgγ) |
| 1154.0 | 693.2 | E(γ): weighted average of 693.5 5 from 32Na β-n decay and 692.6 8 from (32Al,31Mgγ) |
| 1389.8 | 929 | E(γ): from 31Na β-n decay only |
| 2015.14 | 1070.9 | E(γ): other: 1072.7 19 from (32Al,31Mgγ) I(γ): unweighted average of 17.6 30 (2019Ni04) in 31Na β- decay and 10.1 16 from (32Al,31Mgγ) | 1554.3 | E(γ): other: 1555.7 22 from (32Al,31Mgγ) I(γ): weighted average of 20.6 30 (2019Ni04) and 24.0 30 from (32Al,31Mgγ) | 1794.3 | E(γ): other: 1793.4 18 from (32Al,31Mgγ) |
| 2243.66 | 1215.0 | I(γ): weighted average of 12.6 9 (2019Ni04), 11.6 12 (1993Kl02), 11.6 11 (1984Gu19), and 22 7 (1979De02) in 31Na β- decay | 2022.8 | I(γ): weighted average of 33.3 19 (2019Ni04), 33.7 35 (1993Kl02), and 36 4 (1984Gu19) in 31Na β- decay. Other: 32 21 from (32Mg,31Mgγ) | 2193.6 | I(γ): weighted average of 25.9 19 (2019Ni04), 30.2 35 (1993Kl02), 30 4 (1984Gu19), and 29 9 (1979De02) in 31Na β- decay. Other: 37 21 from (32Mg,31Mgγ) |
This nucleus is part of a set of nuclei around n=20 belonging to the "island of inversion " where the ground state is deformed from a spherical shell. The ground state and first excited state spins are critical in proving the intruder dominant configuration (2005Ma96).
Mass measurements: 2013Ch49, 2006Ga04 (also 2006Lu09 from the same group)
Other measurements:
2017Ha23: measured half-life of 31Mg from implant-β(t). 31Mg from 9Be(40Ar,X) reaction with E(40Ar)=69.2 MeV/nucleon from the RIBLL facility at HIRFL, Lanzhou.
2012Yo01 (also 2010Yo08): first application of nuclear orientation method for study of isotope shifts in nuclei. Atomic isotope shifts measured using collinear laser spectroscopy and β-asymmetry with reference to 26Mg for all measurements at CERN-ISOLDE. The data are consistent for 31Mg being in the "Island of Inversion ".
2012Kw02: production cross section measurement in fragmentation of 40Ar beam at 140 MeV/nucleon with 9Be, Ni and 181Ta targets by time-of-flight and energy loss measurements at NSCL facility
2012Zh06: 9Be(40Ar,X) E=57 MeV/nucleon, measured fragment yield, momentum distributions at HIRFL facility; deduced target dependence on production cross section
2006Kh08: cross section and strong absorption radius measurement in Si(31Mg,X) reaction at 52.25 MeV/nucleon
2011Ne14: critical review of experimental data leading to ground and excited states in 31Mg; comparison with calculated levels, J, π, magnetic moments, particle-hole nature using Antisymmetrized molecular dynamics (AMD) with the generator coordinate method.
Theoretical calculations: 35 primary references for structure and three for decay characteristics retrieved from the NSR database (www.nndc.bnl.gov/nsr/) are listed under ’document records’.
Q-value: S(2n)=8652 3, S(2p)=36100 150, Q(β-n)=4671 4 (2021Wa16)