New radioisotopes of niobium and molybdenum—II 88Mo and 89Mo
Abstract
Two new activities have been found in the neutron deficient isotopes of molybdenum produced by (p, pxn) reactions on molybdenum. The half-lives were 27 3 ± 1·4 min and 7·1 min. These activities are assigned to 88Mo and 89Mo respectively on the basis of their genetic relationship with niobium and zirconium isotopes. 88Mo has also been produced by a (p, xn) reaction on niobium.
Positron and γ-ray spectra of these and a few other neutron deficient isotopes of molybdenum have been studied. 88Mo emits 2·5 MeV positrons and a 2·69 MeV γ-ray. 89Mo emits positron groups of energies 4·05 and 4·95 MeV.
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Cited by (13)
Evaluation of cross section data for the low and medium energy cyclotron production of the non-standard positron emitting radionuclide <sup>90</sup>Nb
2023, Radiation Physics and ChemistryThe radionuclide 90Nb (T1/2 = 14.6 h) is a promising non-standard β+-emitter, with potential for use in Immuno-PET. Its production was studied using 90Zr, 91Zr, 93Nb and 89Y targets. Experimental excitation functions of the reactions 90Zr(p,n)90Nb, 91Zr(p,2n)90Nb, 90Zr(d,2n)90Nb, 93Nb(p,4n)90Mo(→90Nb) and 89Y(α,3n)90Nb were critically analyzed. The nuclear model codes TALYS 1.9, ALICE-IPPE, and EMPIRE 3.2 were employed to check the consistency and reliability of the experimental data. A well-developed methodology, based on the experimental data and the results of theoretical nuclear models, was used to calculate the recommended data for each excitation function. The same was done for reactions leading to possible radioisotopic impurities. By using the recommended/reference data, thick target yields were calculated for each production route and its corresponding impurity reactions. After a careful analysis and comparison of all production routes, it is concluded that the 90Zr(p,n)90Nb reaction is better for low energy cyclotrons (20 → 5 MeV), and the 91Zr(p,2n)90Nb and 90Zr(d,2n)90Nb reactions are suitable for medium energy cyclotrons (30 → 12 MeV). The routes 93Nb(p,4n)90Mo→90Nb and 89Y(α,3n)90Nb are suitable for high energy cyclotrons (80 → 31 MeV). For each of these production routes, an optimum energy range is suggested. The recommended results for 90Zr(p,n)90Nb and 91Zr(p,2n)90Nb reactions were validated by comparison with the data for the natZr(p,x)90Nb process.
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 = 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 data sheets for A = 89
1975, Nuclear Data SheetsThe 1961 version of Nuclear Data Sheets for A = 89 and the 1970 Midstream Evaluation, A = 89 [M. W. Johns, J. Y. Park, S. M. Shafroth, D. M. Van Patter, and K. Way, Nuclear Data Tables 8, 373 (1970)], have been revised on the basis of experimental data received prior to August 1, 1975. Results from approximately 150 papers and communications chosen from the extensive literature for this A-chain have been included in the present evaluation. Numerous additional references dealing wtih reaction mechanism studies and nuclear structure theory are not included in this compilation, but are available upon request from the Nuclear Data Project.
Data on nine A = 89 nuclei are presented. Only the half-lives for 89Se and 89Br have been determined. The decay schemes for 89Kr and 89Rb appear to be well established. The decay scheme for 89Sr is particularly simple, but the intensity for the single γ-ray in the decay is not well known. Many spin assignments have been made for levels in 89Sr, 89Y, and 89Zr from a variety of decay and reaction studies. The decay schemes for low-spin and high-spin isomers in both 89Zr and 89Nb appear to be well established, but the energy ordering of the two isomers in 89Nb is not known. On the basis of recent results, it appears that the previously claimed isotope 89Mo has not yet been observed.
A search for <sup>89</sup>Mo
1975, Journal of Inorganic and Nuclear ChemistryWe tried to produce the 89Mo which had been previously reported as having a of 7·1 min. We used the 90Zr(3He, 4n)89Mo, 93Nb(p, 5n) 89Mo, and 92Mo(p, p3n)89Mo reactions. Molybdenum was chemically separated rapidly from the target, but neither new radiations nor the growth of 89Nb were observed. An upper limit on the half-life of 89Mo assuming a spin was set at 2 min and for the assumption at 1 min.
Midstream evaluation, A=88
1970, Atomic Data and Nuclear Data TablesData on the A=88 nuclides, reported since the publication of the last Nuclear Data Sheets in this region (1960), have been studied and evaluated. Presented here are decay and level schemes adopted by the present compilers and summaries of the experimental data on which the adopted values are based. Literature available in June 1969 was discussed at a meeting held at Duke University at that time. Important papers appearing since then (up to June 1970) have either been incorporated into the work or noted in Added in Proof sections.
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Permanent address: Atomic Energy Commission, Pakistan.