High spin states in 89Y
Abstract
States of 89Y, populated through the 87Rb(α, 2n) reaction in the energy range Eα = 30 to 55 MeV. were studied using in-beam γ-ray spectroscopy techniques. Excitation functions, γ-ray angular distributions and γ-γ coincidences were measured. Nine hitherto unknown states above 3.3 MeV were found and their decay modes were determined. These levels are tentatively assigned spin values from up to . Their energies are found to be close to those obtained from coupling the 3−, (5)−, (6)− and(7)− states of the 88Sr core with the single-particle isomeric state at 908.8 keV. The validity of a weak coupling description for these high spin states is further supported by the similarites with the known 87Sr data. The analogy with 87Sr seems however to breakdown regarding the highest spin member of the multiplet. This state appears to lie significantly higher in 89Y. The data confirm the previous information existing on levels below 3.3 MeV, with the exception of a level found at 2894.3 keV and for which a tentative assignment is proposed.
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Cited by (17)
Nuclear Data Sheets for A = 89
2013, Nuclear Data SheetsThe evaluated experimental data are presented for 14 known nuclides of mass 89 (Ge, As, Se, Br, Kr, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh). New data on high–spin excitations are available for 89Kr, 89Rb, 89Sr, 89Tc and 89Ru, including a superdeformed structure in 89Tc. Fluorescence studies in 89Y have revealed a large number of new levels in 7–11 MeV range. New two–neutron transfer data are available for 89Zr. New direct and precise measurement of atomic masses of 89Se, 89Br, 89Kr, 89Rb, 89Mo and 89Tc have greatly improved the Q value landscape in this mass region. This work supersedes previous A=89 evaluation published in 1998Si31, and also the older ones 1989Si20, 1975Ko21, and M.W. Johns et al., Nuclear Data Tables A 8, 373 (1970).
In spite of extensive experimental work on the isobaric nuclei of this mass chain several deficiencies remain. The identification of 89Rh isotope remains unconfirmed. The half–lives of ground states of 89Ge, 89As and 89Rh have not been measured, only the lower limits are estimated from time–of–flight in a reaction and experimental arrangement, where produced and identified. The decay schemes of 89Ge, 89As, 89Se, 89Ru and 89Rh are not known, and those for 89Tc and 89Mo are incomplete. High–lying (neutron unbound) levels in 89Kr, expected to be populated in the decay of 89Br, have not been investigated. The spins and parities for levels in 89Kr are largely unassigned, while for 89Tc and 89Ru, only few low–spin excitations are established. For 89Rb, little information is available for high–spin structures. Detailed gamma–ray data are available for 88Sr(n,γ)89Sr reaction, but most of these γ rays remain unassigned in a level scheme. Excited state data are nonexistent for 89Ge, 89As, 89Se, 89Br and 89Rh. The 89Y and 89Zr are the most extensively studied nuclei in A=89.
Nuclear data sheets for A = 89
1998, Nuclear Data SheetsThe evaluated experimental data are presented for 14 known nuclides of mass 89 (Ge, As, Se, Br, Kr, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh). Excited state data are nonexistent for89Ge,89As,89Se,89Br,89Ru, and89Br. High-spin excitations are known for89Sr,89Y,89Zr,89Nb,89Mo and89Tc; neutron capture ;gg-ray data are available for89Sr (neutrons at thermal energy); and particle-transfer data exist for89Rb,89Sr,89Y,89Nb and89Mo. This work supersedes earlier A = 89 Nuclear Data Sheets (89Si20, 75Ko21).
Neutron-core excitations in the N=50 nucleus <sup>89</sup>Y
1992, Nuclear Physics, Section AHigh-spin states of the N=50 nucleus 89Y up to at 8.7 MeV have been investigated in the (α,2n) reaction by using in-beam γ-ray spectroscopy. Besides singles γ-ray spectra, excitation functions and γγ-coincidences, the angular distribution and linear polarization of the γ-rays have been measured. For 23 of the observed 28 levels, mean lifetimes or limits have been determined by means of the Doppler-shift attenuation of γ-r.f. methods. In order to calculate the stopping of recoils in the two-component RbCl target a new procedure had to be developed. On the basis of all these experiments several new levels as well as many spin/parity values could be uniquely assigned. The most surprising results are the observed high level density at spin and the identification of several fast M1-transitions at high spin. Both results may be explained by the inclusion of neutron particle-hole excitations across the closed N=50 shell. No collective E2 transitions have been found. The experimental results are compared with shell model calculations.
Nuclear data sheets for A = 89
1989, Nuclear Data SheetsThe 1975 version of Nuclear Data Sheets for A=89 has been revised. Detailed level and decay schemes, arguments for Jπ assignments, and experimental data are presented. Some additional information on 89Br and new level schemes for 89Kr, 89Nb, and 89 Mo were obtained. The level schemes of 89Sr, 89Y, and 89Zr were extended mainly by high-spin states but for 89Y also by isobaric analog states.
Collective excitations in <sup>88</sup>Y
1981, Nuclear Physics, Section AHigh-spin states in 88Y were excited through the 87Rb(α, 3n) reaction at energies between 30 and 55 MeV. The population of the previously known 8+ and 9+ members of the multiplet carry most of the total cross section. Above the 8+ state a sequence of 5 levels is observed, which can be interpreted as arising from the coupling of this level with the excitations of the 88Sr core. A similar interpretation is suggested for the 3206.8 keV state which deexcites into the 9+ state. Only a few of the many low-lying low-spin states previously reported are weakly seen with this reaction. The relative cross sections for the different outgoing channels are compared with those observed in the 85Rb(α, xnypzα) reactions and both sets are in turn combined with earlier data obtained with the Zn isotopes to show that it is possible to attain a systematics for the relative strengths.
High-spin states above 3.5 MeV in <sup>91</sup>Nb
1979, Nuclear Physics, Section AHigh-spin states in 91Nb populated by the 89Y(α, 2nγ) reaction were studied at 24.0 MeV and 35.7 MeV incident α-particle energy. Gamma-gamma coincidence and γ-ray angular distribution measurements were made. Several high-spin states in 91Nb were observed at 35.7 MeV bombarding energy which were not observable at 24.0 MeV. The shell model structure of these states is discussed.