The electron-capture and f3+-decay branchings (EC/p+) and delayed proton decays of A =142 isotopes with 61 Z 66 and 3 =140 isotopes with 63 Z 65 were investigated with the OASIS facility on-line at the Lawrence Berkeley Laboratory Super HILAC. Electron capture and positron-decay emission probabilities have been determined for ' Pm and ' 'Sm decays, and extensive decay schemes have been constructed for ' Eu (2.34+0. 12 s), ' Gd(70. 2+0.6 s), Eu(1. 51+0.02 s) and ' Gd(15. 8+0.4 s). Decay schemes for the new isotopes ' Tb (597+17 s) Tb {303+17ms), '" Dy(2. 3+0.3 s), ' Eu (125+2 ms), and ' Tb(2. 4+0.2 s) are also presented.We have assigned y rays to these isotopes on the basis of yy and x y coincidences, and from half-life determinations.Electron-capture and p+-decay branchings were measured for each decay, and pdelayed proton branchings were determined for '4'Dy, ' 'Tb, and ' Tb decays. QEc values, derived from the measured EC/p+ branchings and the level schemes are compared with those from the Wapstra and Audi mass evaluation and the Liran and Zeldes mass calculation. The systematics of the cY =77 isomer decays are discussed, and the intense 0+~1+ and 1+~0+ ground-state beta decays are compared with shell-model predictions for simple spin-Aip transitions. ed -4.5 cm from the source. A schematic view of the detector arrangement is shown in Fig. 1. In the experiments with Fe beams, 8 and 400 s (for A =142) and 8 and 80 s (for A =140) tape cycles were used and the close-in n-type Ge had 24% eSciency while the 90' detector had 52% e%cieney. For the Cr experiments, the tape cycles were 2.4 and 1.6 s, and the two n-type detectors were interchanged. Coincidences between particles, y rays, x rays, and positrons were recorded in an eventby-event mode; all events were tagged with a time signal for half-life information. Singles spectra were taken with 43 1066
Transportation of thermalized primary recoil ions from nuclear reactions by helium flow has been investigated as a means of injecting short-lived radioactive nuclides into an on-line isotope separator. Several short-lived radioactive isotopes of highly nonvolatile elements such as B, Sc, Nb, and W have been separated. The efficiency for heavy nuclides with half-lives above 1 ms is between 1 and 10%. The shortest-lived activity identified in an on-line separation is the 182-/us isomeric state in 207 Bi.PACS numbers: 28.60. + S, 29.25.Cy
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