ADOPTED LEVELS, GAMMAS for 254Es
Author: Balraj Singh | Citation: Nucl. Data Sheets 156, 1 (2019) | Cutoff date: 31-Jan-2019
Full ENSDF file | Adopted Levels (PDF version)
| Q(β-)=1088 keV 3 | S(n)= 5091 keV 4 | S(p)= 4600 keV 6 | Q(α)= 6615.7 keV 15 | ||
| Reference: 2017WA10 |
| References: | |||
| A | 258Md α decay (51.50 d) | ||
| E(level) (keV) | XREF | Jπ(level) | T1/2(level) | E(γ) (keV) | I(γ) | M(γ) | Final Levels | |
| 0.0 | A | (7+) | 275.7 d 5 % β- = 1.74×10-4 8 % ε = ? % α ≈ 100 % SF < 3×10-6 | |||||
| 80.1 1 | A | (8+) | 80.1 2 | 100 | (M1+E2) | 0.0 | (7+) | |
| 84.2 25 | 2+ | 39.3 h 2 % β- = 98 2 % ε = 0.076 7 % α = 0.32 1 % IT < 3 % SF < 0.045 | ||||||
| 171.1 1 | A | (9+) | 91.0 3 171.1 2 | 26 16 100 33 | [M1+E2] [E2] | 80.1 0.0 | (8+) (7+) | |
| 214.7 2 ? | A | 214.7 2 ? | 100 | [D,E2] | 0.0 | (7+) | ||
| 289.9 3 ? | A | (7+) | ||||||
| 376.8 2 | A | (8+) | 86.9 2 ? 205.7 2 296.7 2 376.8 4 | 10 3 22 8 100 17 32 13 | (M1+E2) [M1+E2] [M1+E2] [M1+E2] | 289.9 171.1 80.1 0.0 | (7+) (9+) (8+) (7+) | |
| 403.8 3 | A | 189.1 2 ? | 100 | [D,E2] | 214.7 | |||
| 447.9 1 | A | (8-) | 71.1 1 276.8 1 367.8 1 447.9 1 | 8.0 5 20.2 19 100 7 37 4 | (E1) (E1) (E1) (E1) | 376.8 171.1 80.1 0.0 | (8+) (9+) (8+) (7+) | |
| 469.2 2 | A | (7+:10+) | 298.1 3 389.1 2 | 47 14 100 23 | [D,E2] [D,E2] | 171.1 80.1 | (9+) (8+) | |
E(level): From least-squares fit to Eγ values
| E(level) (keV) | Jπ(level) | T1/2(level) | E(γ) | I(γ) | M(γ) | Final Levels | |
| Band 1 - Probable Kπ=(7+), g.s. band. | |||||||
| 0.0 | (7+) | 275.7 d 5 % β- = 1.74×10-4 8 % ε = ? % α ≈ 100 % SF < 3×10-6 | |||||
| 80.1 1 | (8+) | 80.1 2 | 100 | (M1+E2) | 0.0 | (7+) | |
| 171.1 1 | (9+) | ||||||
| E(level) (keV) | Jπ(level) | T1/2(level) | E(γ) (keV) | Multipolarity | Mixing Ratio | Conversion Coefficient | Additional Data |
| 80.1 | (8+) | 80.1 2 | (M1+E2) | 1.25 25 | 49 | α=49 6, α(L)=35 4, α(M)=9.9 12, α(N)=2.8 4, α(O)=0.70 9, α(P)=0.115 13, α(Q)=0.00127 25 | |
| 171.1 | (9+) | 91.0 3 | [M1+E2] | 25 | α=25 13, α(L)=18.2 89, α(M)=5.0 28, α(N)=1.42 78, α(O)=0.36 19, α(P)=0.060 28, α(Q)=0.00109 79 | ||
| (9+) | 171.1 2 | [E2] | 2.30 | α=2.30, α(K)=0.1482 21, α(L)=1.546 23, α(M)=0.441 7, α(N)=0.1246 19, α(O)=0.0313 5, α(P)=0.00509 8, α(Q)=3.22×10-5 5 | |||
| 214.7 | 214.7 2 | [D,E2] | 2.5 | α=2.5 24 | |||
| 376.8 | (8+) | 86.9 2 | (M1+E2) | 30 | α=30 17, α(L)=22 12, α(M)=6 4, α(N)=1.7 10, α(O)=0.44 25, α(P)=0.07 4, α(Q)=0.0013 9 | ||
| (8+) | 205.7 2 | [M1+E2] | 3.2 | α=3.2 22 | |||
| (8+) | 296.7 2 | [M1+E2] | 1.1 | α=1.1 9 | |||
| (8+) | 376.8 4 | [M1+E2] | 0.6 | α=0.6 5 | |||
| 403.8 | 189.1 2 | [D,E2] | 3.5 | α=3.5 34 | |||
| 447.9 | (8-) | 71.1 1 | (E1) | 0.366 | α=0.366 | ||
| (8-) | 276.8 1 | (E1) | 0.0556 | α=0.0556 | |||
| (8-) | 367.8 1 | (E1) | 0.0308 | α=0.0308 | |||
| (8-) | 447.9 1 | (E1) | 0.0209 | α=0.0209 | |||
| 469.2 | (7+:10+) | 298.1 3 | [D,E2] | 0.98 | α=0.98 93 | ||
| (7+:10+) | 389.1 2 | [D,E2] | 0.47 | α=0.47 44 |
Additional Level Data and Comments:
| E(level) | Jπ(level) | T1/2(level) | Comments |
| 0.0 | (7+) | 275.7 d 5 % β- = 1.74×10-4 8 % ε = ? % α ≈ 100 % SF < 3×10-6 | μ=4.35 41 (2009Se09,2011Gu11,2014StZZ) 1985Ok04 determined β- decay/total=1.74×10-6 8 from relative intensities of 254Es and 254Fm α’s; 254Fm was in equilibrium with 254Es. Earlier measurement: %β-<2×10-4 (1966Mc02). E(level): 1985Ok04 determined β- decay/total=1.74×10-6 8 from relative intensities of 254Es and 254Fm α’s; 254Fm was in equilibrium with 254Es. Earlier measurement: %β-<2×10-4 (1966Mc02). Probable Kπ=(7+), g.s. band. |
| 80.1 | (8+) | E(level): Probable Kπ=(7+), g.s. band. | |
| 84.2 | 2+ | 39.3 h 2 % β- = 98 2 % ε = 0.076 7 % α = 0.32 1 % IT < 3 % SF < 0.045 | μ=2.90 7 (1975Go05,2014StZZ), Q=+3.7 5 (1975Go05,2016St14) %ε/%β-=7.8×10-4 6 (1963Ph01) from the rates of α emission and spontaneous fission in 254Fm and 254Cf daughters, chemically separated from 254Es. E(level): %ε/%β-=7.8×10-4 6 (1963Ph01) from the rates of α emission and spontaneous fission in 254Fm and 254Cf daughters, chemically separated from 254Es. |
| 171.1 | (9+) | E(level): Probable Kπ=(7+), g.s. band. | |
| 289.9 | (7+) | No γ decay of this level is known. | |
| 403.8 | The gamma decay of this level is largely unknown. | ||
| 447.9 | (8-) | By assuming that the 80.0- and 171.1-keV levels are the 8+ and 9+ states of the g.s. rotational band, 1993Mo18 pointed out that the relative intensities of the 276.8-, 376.8- and 447.9-keV gammas disagree with the expected relative Iγ values to 7+, 8+, and 9+ rotational band members; and they proposed that the 447.9-keV level has an admixture from another rotational band. E(level): By assuming that the 80.0- and 171.1-keV levels are the 8+ and 9+ states of the g.s. rotational band, 1993Mo18 pointed out that the relative intensities of the 276.8-, 376.8- and 447.9-keV gammas disagree with the expected relative Iγ values to 7+, 8+, and 9+ rotational band members; and they proposed that the 447.9-keV level has an admixture from another rotational band. |
1954Fi14: 254Es isomer of 39 hours produced and identified in neutron-activation of 253Es at Argonne National lab, measured half-life
1954Ch23, 1955Ha35: 254Es isomer of 39 hours produced and identified in neutron-activation of Pu and higher mass nuclides at Berkeley, followed by chemical separation and measurement of half-life β- activity.
α 272-d activity in 254Es was reported by B.γ. Harvey et al., in 1955 as quoted on page 960 of book by 1964Hy02.
Later half-life and other measurements of 254Es decay: 1956Jo09, 1958Sc35, 1962Un01, 1973Ah04, 1975Ah04, 1988Po05
2009Se09, 2011Gu11: 254Es produced through the irradiation of 252Cf by neutrons at a reactor in Dimitrovgrad, Russia, followed by β- decay to 253Es, which then captured a neutron through the 253Es(n,γ) reaction to produce 254Es. The sample was radiochemically separated before being mass separated and implanted into an Fe foil at Bonn, Germany. Nuclear orientation experiments were performed in Leuven, Belgium. The α decays were detected by six Si PIN-diodes and γ rays by two large volume HPGe detectors. Count rates were recorded for both oriented and nonoriented nuclei, from which the angular distribution was determined. Measured magnetic dipole moment from the anisotropy of α particles from oriented nuclei, and the hyperfine magnetic field for Es impurities in Fe host. See also 2010Gu05, 2006Gu32, 2005Se08 and 2004Gu22 from the same group as 2009Se09 and about the same topic
Theoretical studies: consult the NSR database at www.nndc.bnl.gov for 29 references dealing with theoretical calculations of half-lives for different decay modes, binding energies, fission characteristics, and other nuclear structure aspects.
Levels: 1993Mo18 proposed a band based on bandhead 6- at 214.7 keV, with band members of 7- at 289.9, 8- at 376.8 and 9- at 469.2 keV, with configuration=π3/2[521]~#ν9/2[615], Kπ=6-. But theoretical analysis by 2007Sa02 does not support this conjecture as the calculated energy of the 6- bandhead for this configuration is >350 keV. In addition, 376.8 level is assigned 8+ by 2007Sa02 from agreement of the theoretical energy for configuration=π7/2[633]~#ν9/2[615]
Gammas: The level scheme given here is as proposed by 1993Mo18 in their study of α and γ data 258Md α decay. It is not considered complete by the evaluators as information about multipolarities and mixing ratios is generally missing. There is also a serious problem with a non-physical negative transition intensity balance at the 171-keV level in 258Md α decay
Q-value: S(2n)=11450 50, S(2p)=11120 200 (syst) (2017Wa10)