New radioisotopes of niobium and molybdenum—I 88Nb
Abstract
A new radioisotope of half-life 21 min has been observed in the neutron deficient isotopes of niobium produced by (p, pxn) and (p, 2pxn) reactions with 340 MeV protons. The activity is assigned to 88Nb on the basis of its genetic relationship to 88Zr.
Half-lives of the known isotopes 89Nb, 89mNb and 90Nb have been determined as 2·0 hr, 42 min and 14·7 hr respectively.
Positron and γ-ray spectra of these isotopes have been studied. 88Nb emits 3·2 MeV positrons and 0·20, 0·72, 0·97 and 1·42 MeV γ-rays.
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Cited by (11)
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.
Discovery of yttrium, zirconium, niobium, technetium, and ruthenium isotopes
2012, Atomic Data and Nuclear Data TablesCurrently, thirty-four yttrium, thirty-five zirconium, thirty-four niobium, thirty-five technetium, and thirty-eight ruthenium isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.
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).
Nuclear data sheets for A = 88
1976, Nuclear Data SheetsThe Midstream Evaluation, A = 88 [Nuclear Data Tables A8, 345–371 (1970)] has been revised on the basis of experimental data received before September 1, 1975. Data for the nine known members of the A = 88 isobar are presented.
Very little is known about 88Se and the available data are inconsistent. The γ-ray spectrum following the 88Br decay has been measured. The resulting level scheme for 88Kr is shown in Drawing 2. The dashed levels result from energy sums involving only two γ-rays and no coincidence data. These data and the 86Kr(t,p) data indicate that the levels at 1644.1 keV (β−) and 1654 keV (t,p) are not equivalent. More decay and reaction data are required before the 88Kr level properties can be considered firm. The γ-rays following the 88Kr β-decay are well established. The agreement of the resulting 88Rb level scheme with that obtained from the 87Rb(d,p) reactions is quite good. The 88Rb β-decay has been well established through many extensive measurements using several different source preparations. The levels of 88Sr have been investigated through many reactions (more than 20 given here) and the 88Rb β- and 88Y ε-decays. Adopted levels through 4.85 MeV are given on the Data Sheets. Above 4.85 MeV inconsistencies in the various energy calibrations obscure the assignment of corresponding levels. A detailed discussion of the various 88Sr(n,γ) experiments can be found in 69Ly07. The 88Y ε-decay is presented as an adopted scheme derived from data discussed in ten publications. The levels of 88Y are well established through many reactions including several (charged particle, nγ) which provide some very accurate level energies. The simple 88Zr ε-decay is shown on Drawing 1. The adopted level properties are from the 90Zr(p,t)88Zr reactions. These data correspond well through 3 MeV. The 88Nb ground-state and isomeric ε-decays need further work. The 14.3-m decay data presented here are in poor agreement with a recent measurement by 74Ba55 which identifies an additional 26 γ-rays, 18 of which are not placed in the decay scheme. The tentative assignment of Jπ(88gNb)=(8+) and Jπ(88mNb)=(4−) are based on weak arguments and should be reconsidered in the light of new decay data. The relative position of these levels is unknown. Very little data are available for 88Mo.
In a few cases unpublished data have been frequently cited by other researchers. These unpublished data have been included for reference and are clearly marked as such. The Adopted Properties were not influenced by these data.
Nuclear reaction cross-sections for 14·7 MeV neutrons on <sup>99</sup>Tc
1973, Journal of Inorganic and Nuclear ChemistryCross-sections for 14·7 ± 0·3 MeV neutron-induced nuclear reactions on 99Tc were determined by the activation technique using Ge(Li) detector γ-ray spectroscopy and fast chemical separation. The results are: ; ; and . The cross-section for the reaction 99Tc(n, 2n)98Tc is estimated from theoretical considerations to be 1227 ± 226 mb. The data are discussed with respect to the cross-section systematics at this energy.
A systematic investigation of (n,t) reactions at 14-15 MeV on medium and heavy mass nuclei
1973, Journal of Inorganic and Nuclear Chemistry(n,t) Reaction cross-sections have been measured at En = 14·6 ± 0·4 MeV for 32S, 40Ca, 50Cr, 54Fe, 64Zn, 70Ge, 89Y, 92Mo, 139La and 197Au by the activation technique in combination with specific radiochemical methods. The measured cross-sections lie in the microbarn region. Possible mechanisms of the (n,t) reaction are discussed. A study of the systematics of this reaction has been carried out and some of the observed trends in reaction cross-sections are described. Similarly to the (n,p) and (n,α) reactions, the (n,t) reaction cross-sections for elements with Z between 24 and 92 decrease with increasing asymmetry parameter of the target nucleus.
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