ADOPTED LEVELS for 218U
Author: Balraj Singh | Citation: ENSDF | Cutoff date: 10-Jun-2021
Authors: Balraj Singh, M.S. Basunia, Murray Martin Et Al., | Citation: Nucl. Data Sheets 160, 405 (2019) | Cutoff date: 30-Oct-2019
Full ENSDF file | Adopted Levels (PDF version)
| S(n)= 9150 keV SY | S(p)= 2449 keV 19 | Q(α)= 8775 keV 9 | |||
| Reference: 2021WA16 |
| E(level) (keV) | Jπ(level) | T1/2(level) |
| 0 | 0+ | 0.65 ms +8-7 % α = 100 |
| 2105 19 | (8+) | 0.56 ms +26-14 % IT = ? % α = ? |
Additional Level Data and Comments:
| E(level) | Jπ(level) | T1/2(level) | Comments |
| 0 | 0+ | 0.65 ms +8-7 % α = 100 | Reduced α-width=53 keV +7-6 (2021Zh22, in Rasmussen formalism) suggests unhindered α transition, consistent with g.s., 0+ to g.s., 0+ α transition. |
| 2105 | (8+) | 0.56 ms +26-14 % IT = ? % α = ? | Only the α decay has been observed with Eα=10678 17 (2007Le14,2005Le42), 10701 30 (2015Ma37) and 10685 38 (2018Ya01). |
218U produced in 197Au(27Al,6n), and identified as parent of 214Th (1992An04). 1997SaZQ reported a cross section of 1.7 nb 12 at E=161 MeV for this reaction.
2007Le14 (also 2005Le42): 218U produced in 182W(40Ar,4n),E=186 MeV; fusion products were separated from beam particles with the RITU gas-filled separator and implanted into the DSSD of the GREAT spectrometer at the RITU focal plane. Measured half-lives of g.s. and an isomer
2015Ma37: 218U produced and identified in 182W(40Ar,4n), E(40Ar)=189.5 MeV using the Sector-Focusing cyclotron facility at HIRFL-Lanzhou. The evaporation residues (ERs) were separated from the incident beam particles using gas-filled recoil separator for heavy ions (SHANS). Measured Eα, (residues)α1α2 correlations, where α1 is from parent nucleus and α2 from daughter nucleus, half-lives. The residues and α particles were detected by using multiwire proportional gas counter (MWPC) and position-sensitive silicon strip detectors (PSSD). From Fig. 2 of two-dimensional plot of mother and daughter α-decay energies for correlated (implants)-α1-α2 events, it appears that two decay were observed for the ground state and one for the isomer.
2018Ya01: 218U g.s. and isomer produced in 187Re(36Ar,4np), E(36Ar)=191.5 MeV reaction, followed by separation of fragments using SHANS separator and detection of (implants)α-correlated decay chains at HIRFL-Lanzhou accelerator facility. Authors reported three correlated decay chains for the g.s., and two chains for the isomeric state.
2021Zh22: 218U produced and identified in 184W(40Ca,α2n), E(40Ca)=190, 206 MeV using the Sector-Focusing cyclotron facility at HIRFL-Lanzhou. The evaporation residues (ERs) were separated from the incident beam particles using gas-filled recoil separator for heavy ions (SHANS). Measured Eα, (residues)α1α2 correlations, where α1 is from parent nucleus and α2 from daughter nucleus, and half-life. The residues and α particles were detected using multiwire proportional gas counter (MWPC) and position-sensitive silicon strip detectors (PSSDs). The α particles escaping the PSSD in the backward direction were collected by a system of eight silicon detectors. Energy resolution (FWHM) for α particles was 35 keV for Eα=6-9 MeV. α total of 76 Er-α correlated chains were observed which were assigned to the decay of 218U g.s. Comparison with shell-model calculations.
2021Zh22, 2018Ya01 and 2015Ma37 are from the same group and laboratory, shared by many of the same authors.
Theory references: consult NSR database (www.nndc.bnl.gov/nsr/) for 36 primary references for calculations of half-lives of radioactive decays, and 16 for nuclear structure
Q-value: Estimated uncertainty=80 keV (2021Wa16)
Q-value: Q(ε)=3245 23, S(2n)=17310 30, S(2p)=2982 18, Q(εp)=2400 17 (2021Wa16)