On Positive Parity Levels of High Angular Momentum in^69,71,73Ge

Abstract

Results of an attempt to establish in 69,71,73Ge the low-lying states of the presumed 1g 9/2 ⊗ core configuration are reported. The excited states in these nuclei were formed in the 66,68,70Zn(α,n) compound reactions mainly at 14.2 MeV incident energy. Properties of the states were assigned from investigations of the prompt γ-ray transitions. Measuring γ-γ coincidences, yield functions, angular distributions (and in a few cases also linear polarization) of γ-rays, evidences were found for states in 69 Ge: 1 350.4 keV 11/2+, 1 407.0 keV 13/2+, 2 017.9 keV 11/2+ or 13/2+, 2 119.2 keV 9/2+, 11/2+ or 13/2+, 3 075.5 keV 13/2+ or 15/2+, (and tentatively: 2 474.8 keV 11/2+ or 13/2+, and 2 754.6 keV 13/2+ or 15/2+). 71 Ge: 589.7 keV 7/2+, 1 037.8 keV (7/2 or 9/2), 1 172.6 keV 13/2+, 1 192.3 keV 11/2+, 1 205.2 keV (5/2+), 1 477.0 keV 11/2+, 1 559.3 keV, 1 566 keV, 1 959.7 keV 11/2+ or 13/2+, 2 299.2 keV 17/2+, 2 314.2 keV 15/2+ (and tentatively 1 697.8 keV). 73 Ge: 659.0 keV 9/2+, 825.8 keV 13/2+, 868.1 keV 11/2+, 1 610.3 keV 9/2+ or 13/2+, 1 871.6 keV 17/2+.

Structure of69Ge

“…The J~ assignments of 5/2-, 1/2-, 3/2 and 3/2-for these states, respectively, have been confirmed by nuclear reaction works [-2, 3, 8] and inbeam spectroscopy works [4,6,7]. Subsequently, the state has been reported in several other works [3][4][5][6], with similar conclusions. The results of nuclear reaction works indicate that the ground state, 86.79 and 374.1 keV states in 69Ge contain substantial single neutron components of lf5/2, 2pl/2 and 2p3/2 orbitals, respectively, in their wave functions.…”

The level structure of69Ge

“…,.oo, [5] could not be found in our coincidence spectra. But as the 712.2 keV transition is seen in our singles spectra this level cannot be excluded.…”

“…Some ambiguities about low spin data could be clarified. Quite recently the same reaction at E~= 14.2 MeV was used by Forssten et al [5] to study positive parity levels of high angular momentum. The results will be compared.…”

High spin levels in 70Ga via 68Zn(α, pnγ) 70Ga

“…So it seems reasonable to hope to reach high spin states in 70Ga via 68Zn(a, pny)7oGa at Ea ~ 30 MeV. Indeed the 199/2-2P3/2 proton splitting (1 972 keV in 69Ga [13]) and the small 199/2-2pl/2 neutron splitting (198 keV in ' 1 Ge [14]) enables us to build high spin states up to 9 + . As a support we may note the work of C. C. Lu et al [15] 68Zn(a, 2ny)'°Ge which was used in our study of 7 'Ge [17] and 68Zn(a, pn7)7'Ga with a cross section (estimated by means of the y transitions to the G.S.)…”