ADOPTED LEVELS for 218Pa
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)
| Q(β-)=-3245 keV 23 | S(n)= 6476 keV 22 | S(p)= 845 keV 21 | Q(α)= 9791 keV 12 | ||
| Reference: 2021WA16 |
| E(level) (keV) | Jπ(level) | T1/2(level) |
| 0 | (8-) | 109 µs 5 % α = 100 |
| 82 21 | (1-) | 135 µs +62-32 % α = 100 |
Jπ(level): Assigned by 2020Zh01, based on the systematics of α decays of odd-proton, n=127 isotones of 212At, 214Fr and 216Ac, with further support from shell-model calculations.
Additional Level Data and Comments:
| E(level) | Jπ(level) | T1/2(level) | Comments |
| 0 | (8-) | 109 µs 5 % α = 100 | The α decay feeds the (5+) g.s. and a (4+) excited state at 92 keV in 214Ac, as proposed in 1979Sc09. |
| 82 | (1-) | 135 µs +62-32 % α = 100 | The α decay feeds the (5+) g.s. and a (4+) excited state at 92 keV in 214Ac, proposed by 2020Zh01. |
1979Sc09: 218Pa produced and identified in 181Ta(40Ar,xn) reaction, measured excitation function.
2000He17 (also 1996An21): 170Er(50Ti,X),E=150-211 MeV; measured T1/2
1999Bo52: measured yield in 197Au(26Mg,X),E<164 MeV
2001Ni06: measured yield in Ce(82Se,X)
2005Li17: measured yield in 9Be(238U,X)
2020Zh01: 218Pa produced and identified in 182W(40Ar,p3n), E(40Ar)=190 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. The γ rays were detected in coincidence mode with α particles and recoils using a Ge Clover-detector and two HPGe detectors. According to Fig. 1b showing (recoil)α-coin spectrum, a large number of recoil-α correlated chains were observed, which were assigned to the decay of 218Pa g.s. In addition, an isomeric state in 218Pa was also discovered, consistent with systematics of α decays for odd-proton n=127 isotones, and with shell-model calculations.
Theory references: consult NSR database (www.nndc.bnl.gov/nsr/) for ten primary references for calculations of half-lives of radioactive decays, and two for nuclear structure
Q-value: Q(ε)=6283 21, S(2n)=15320 30, S(2p)=4078 20, Q(εp)=2658 21 (2021Wa16)