Énergies et intensités des raies γ dans la capture des neutrons thermiques par le strontium
Abstract
The neutron capture γ-ray spectra of the reaction Sr(n, γ) have been investigated using a Ge(Li) spectrometer. A pure thermal neutron beam is obtained by Bragg reflection from a lead crystal. A total of 144 gamma lines has been observed. A neutron separation energy of for 87Sr and for 88Sr was deduced. The intensities per 100 neutrons captured have been evaluated for a large number of transitions, specially in 88Sr. A transition scheme is proposed and discussed for 87Sr and 88Sr.
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Cited by (15)
Nuclear Data Sheets for A = 87
2015, Nuclear Data SheetsThe evaluated experimental data are presented for 14 known nuclides of mass 87 (Ga, Ge, As, Se, Br, Kr, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru). New datasets have been added for 87Ga, 87Se, 87Kr, 87Rb, 87Sr, 87Nb, and 87Tc. The observation of and new lifetime measurements for 87As at the NSCL Coupled Cyclotron Facility and the Oak Ridge Isochronous Cyclotron at the HRIBF–ORNL Facility are included in the adopted levels for this isotope. The new evaluation also includes an isomeric level at unknown energy for 87Tc, changes to the adopted levels for 87Nb based on newly published data including an extension of the high spin levels and new lifetime measurements, and new heavy ion data for 87Kr. New high spin levels for 87Rb were observed, indicating possible neutron core excitations. In addition, the ground state lifetime of 87Rb has been revised and a new lifetime measurement for an excited level in 87Rb indicates a possible proton spin flip. New excitation levels have been observed for the first time in 87Se. New direct and precise measurement of atomic masses of 87Tc, 87Mo, 87Nb, 87Zr, 87Mo and 87Tc have greatly improved the Q value landscape in this mass region. This work supersedes the previous A=87 evaluation published in 2002He09, and Q values for all isotopes were updated to incorporate the mass evaluation in 2012Wa38.
Nuclear Data Sheets for A = 88
2014, Nuclear Data SheetsThe experimental results from the various reaction and radioactive decay studies leading to nuclides in the A=88 mass chain have been reviewed. Nuclides ranging from Ge (Z=32) to Ru (Z=44) are included. For these nuclei, level and decay schemes, as well as tables of nuclear properties, are given. This work supersedes the previous evaluation of the data on these nuclides (G. Mukherjee, A.A. Sonzogni – Nucl.Data Sheets 105, 419 (2005)).
Nuclear data sheets for A = 88
2005, Nuclear Data SheetsExperimental data on ground- and excited-state properties for all known nuclei with mass number A = 88 have been compiled and evaluated. States populated in radioactive decay, as well as in nuclear reactions, have been considered. For these nuclei, level and decay schemes, as well as tables of nuclear properties, are given. This work supersedes the 1988 evaluation by H.-W. Muller (1988Mu09).
Nuclear data sheets for A = 87
2002, Nuclear Data SheetsThe experimental results from the studies of the radioactive decays and nuclear reactions leading to nuclides in the A=87 mass chain have been reviewed. These data are summarized and presented, together with adopted level schemes and properties. The data for the decay of 87Nb (2.6 min) and the decay of 87Nb (3.75 min) are both very incomplete, so new studies would be useful.
Nuclear data sheets for A = 88
1988, Nuclear Data SheetsThe 1976 version of Nuclear Data Sheets for A=88 (76Bu07) has been revised. Detailed level and decay schemes, arguments for Jπ assignments, and experimental data are presented.
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.