First -and -spectroscopic decay studies of the N 82 r-process ''waiting-point'' nuclide 130 Cd have been performed at CERN/ISOLDE using the highest achievable isotopic selectivity. Several nuclear-physics surprises have been discovered. The first one is the unanticipatedly high energy of 2.12 MeV for the [g 9=2 g 7=2 1 level in 130 In, which is fed by the main Gamow-Teller transition. The second surprise is the rather high Q value of 8.34 MeV, which is in agreement only with recent mass models that include the phenomenon of N 82 shell quenching. Possible implications of these new results on the formation of the A ' 130 r-process abundance peak are presented.

The use of chemically selective laser ionization combined with b-delayed neutron counting at CERN/ISOLDE has permitted identification and half-life measurements for 623-ms 61 Mn up through 14-ms 69 Mn. The measured half-lives are found to be significantly longer near N 40 than the values calculated with a quasiparticle random-phase-approximation shell model. Gamma-ray singles and coincidence spectroscopy has been performed for 64,66 In addition to the clear nuclear-structure interest, the neutron-rich Fe-group nuclei may also play an important role as possible seed nuclei in the astrophysical r process [13]. In the present paper, we report new measurements for the half-lives of heavy Mn nuclides up to 69 Mn and for the level structure of 64,66 Fe populated in the decays of 64,66 Mn.Manganese isotopes were produced at CERN by 1-GeV proton-induced spallation of uranium in a thick UC 2 target at the ISOLDE facility. The ionization of the Mn atoms was accomplished using a chemically selective, three-step laser resonance excitation scheme as described in detail earlier [14].Beams of Mn nuclides with masses differing by DA $ 4 were transported separately to two different beam lines equipped with moving tape systems where b-delayed neutron (d.n.) multiscaling and g-ray singles and coincidence measurements could be performed independently. In both cases, counting took place directly at the point of deposit, and the tape systems were used to remove the daughter nuclides as well as unavoidable surfaceionized isobaric Ga activities. Because the Mn half-lives being sought are in the millisecond range, data acquisition in both systems was initiated by the proton pulses from the CERN proton-synchrotron booster (PSB), separated by a multiple of 1.2 s, and continued for 1.0 s for each cycle.Beta-delayed neutron data of high statistical quality were collected by multiscaling measurements using the Mainz 4p 3 He neutron counter. The time dependence of the counting rates for 65 69 Mn is shown in Fig. 1. The decay curves were fitted with a constant small d.n.-background component up through A 65. Because there exist no measured d.n.-emission probabilities (P n values) for the A . 65 daughter and granddaughter isobars, the fits of the heavier isotopes were performed using theoretical P n values [10] along with the known half-lives [5,7,8,15]. For A 66 68, the contributions from d.n. emission of the Fe and Co isobars are quite small and actually do not affect the Mn half-life fits. For A 69, however, a multicomponent fit was necessary to account for the significant Fe and Co d.n. branches. The resulting data are summarized in Table I 0031-9007͞99͞82(7)͞1391(4)$15.00

The isotopes 68 74 Ni, of interest both for nuclear physics and astrophysics, have been produced in proton-induced fission of 238 U and ionized in a laser ion guide coupled to an on-line mass separator. Their b decay was studied by means of b-g and g-g spectroscopy. Half-lives have been determined and production cross sections extracted. A partial level scheme is presented for 73 Cu and additional levels for 71 Cu, providing evidence for a sharply lowered position of the p1f 5͞2 orbital as occupancy of the n1g 9͞2 state increases. The latter may have a clear impact on the predicted structure and decay properties of doubly magic 78 Ni. [S0031-9007 (98)07340-2]

The 2ZNe(c~,7)26Mg and 22Ne(cq n)2SMg reactions were investigated for E~(lab) from 0.71 to 2.25 MeV. Neon gas enriched to 99% in 22Ne was recirculated in a differentially pumped gas target system of the extended type. The 7-ray transitions were observed with Ge(Li) detectors and the neutrons with 3He ionization chambers. A previously known resonance at ER(lab)= 2.05 MeV was verified and 15 new resonances were found in the energy range covered, with the lowest at ER(lab)=0.83 MeV. Information on resonance energies, widths, strengths, 7-ray branching ratios, as well as J" assignments, is reported. The energy range investigated corresponds to the important temperature range of T9 from 0.3 to 1.4 (109 K), for which the astrophysical rates were determined for both reactions. The results show that the ratios of the rates for 22Ne(c~,n)2SMg and 22Ne(c~, 7)26Mg are significantly smaller than the previously adopted values, e.g., by at least a factor of 60 near T9=0.65. Thus, the 22Ne(e, n)25Mg reaction will likely play a smaller role as a neutron source for s-process nucleosynthesis, than has frequently been assumed.