Review: <i>California's Changing Environment</i>, by Raymond F. Dasmann

Runte, Alfred

doi:10.2307/3639016

Cited by 2 publications

(3 citation statements)

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“…Until recently, the principal data available for neutronrich nuclides between 48 Ca and 78 Ni were the γspectroscopic data obtained in the 1980's at GSI [1,2] and the nuclear masses reported by Seifert et al [3]. During the past three years, however, a number of new experimental studies on level structures and decay properties on Fe-group nuclei have been performed [4][5][6][7][8][9].…”

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confidence: 99%

Decay of Neutron-Rich Mn Nuclides and Deformation of Heavy Fe Isotopes

et al. 1999

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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

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confidence: 99%

Decay of Neutron-Rich Mn Nuclides and Deformation of Heavy Fe Isotopes

et al. 1999

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“…The structure of the neutron rich odd-A gallium isotopes (Z = 31) has been studied in the past by means of β decay [1][2][3], single and multi-particle transfer reactions [4][5][6][7][8][9] and more recently by deep inelastic reactions [10]. The two neutron transfer reaction data suggest a change in structure between 71 Ga 40 and 73 Ga 42 , which is most probably related to the structural difference observed between 72 Ge 40 and 74 Ge 42 (Z = 32), where both the 72 Ge 40 (t,p) 74 Ge 42 and 74 Ge 42 (p,t) 72 Ge 40 reactions strongly populate the excited 0 + state, indicating a shape transition [11].…”

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confidence: 99%

“…No evidence for a doublet near the ground state of 73 Ga was obtained from the Overview of the selected γ transitions in 73 Ga. Previously known γ-ray energies and available uncertainties are taken from[1,2,6,7,10]. Number of counts are extracted from fig.2.…”

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Coulomb excitation of 73Ga

Diriken,

Stefanescu,

Balabanski

et al. 2010

Preprint

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The B(E2; Ii → I f ) values for transitions in 71 31 Ga40 and 73 31 Ga42 were deduced from a Coulomb excitation experiment at the safe energy of 2.95 MeV/nucleon using post-accelerated beams of 71,73 Ga at the REX-ISOLDE on-line isotope mass separator facility. The emitted γ rays were detected by the MINIBALL γ-detector array and B(E2; Ii → I f ) values were obtained from the yields normalized to the known strength of the 2 + → 0 + transition in the 120 Sn target. The comparison of these new results with the data of less neutron-rich gallium isotopes shows a shift of the E2 collectivity towards lower excitation energy when adding neutrons beyond N = 40. This supports conclusions from previous studies of the gallium isotopes which indicated a structural change in this isotopical chain between N = 40 and N = 42. Combined with recent measurements from collinear laser spectroscopy showing a 1/2 − spin and parity for the ground state, the extracted results revealed evidence for a 1/2 − , 3/2 − doublet near the ground state in 73 31 Ga42 differing by at most 0.8 keV in energy.

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Review: California's Changing Environment, by Raymond F. Dasmann

Cited by 2 publications

References 0 publications

Decay of Neutron-Rich Mn Nuclides and Deformation of Heavy Fe Isotopes

Decay of Neutron-Rich Mn Nuclides and Deformation of Heavy Fe Isotopes

Coulomb excitation of 73Ga

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