The decay of 129Ba
Abstract
The decay of 129Ba has been investigated with Ge(Li) and scintillation detectors used in both singles and coincidence modes. A total of 118 γ-rays are assigned to the decay of this isotope. Precise energies and intensities have been determined and are compared with internal conversion measurements. A decay scheme incorporating 100 γ-transitions is proposed on the basis of coincidence experiments and energy sums. The multipolarities of low-energy transitions up to 221 keV are calculated from a knowledge of the K- and L-con version electron intensities and our γ-ray intensities. Spins for the first few levels in 129Cs are suggested on the basis of gB-decay characteristics and the multipolarities of the low-energy transitions. The low spin state of 129Ba decays to the ground state and to the 135 and 221 keV levels of 129Cs with a large positon branching, whereas no positon decay has been observed from the high-spin state of 129Ba.
References (15)
- D. Strominger et al.
Rev. Mod. Phys.
(1958) - C.C. Thomas et al.
J. Am. Chem. Soc.
(1950) - R.W. Fink et al.
J. Am. Chem. Soc.
(1950) - R.W. Fink et al.
Phys. Rev.
(1953) - W. Henkes
Phys. Rev.
(1959) - E. Arbmann et al.
Nucl. Phys.
(1961) - A.C. Li et al.
Phys. Rev.
(1966)
Cited by (15)
Lifetime measurement in picoseconds for the excited states of <sup>129</sup>Cs
2021, Nuclear Physics AThe high-spin states of 129Cs were populated using the fusion-evaporation reaction 124Sn(11B, 6n)129Cs. We have studied the nuclear structure properties – signature splitting and reduced transition probabilities (B(E2)) – of many excited states in 129Cs. Lifetimes in picoseconds were measured using the Doppler Shift Attenuation Method (DSAM). We employed two gating procedures, Gating on transition above (GTA) and Gating on transition below (GTB), to obtain the experimental results consistently. We carefully analyzed the data by incorporating the effects related to nuclear reaction, e.g., change in the velocity and cross section of residues when moving in a medium. Theoretical investigations were carried out for two yrast bands – a positive-parity based on πg7/2, and another negative-parity based on πh11/2 – using the single quasi-particle rotor model (PRM). For both bands, we found the same deformation parameter values , (Lund convention) by simultaneously matching the experimental and theoretical results for the signature splitting and B(E2) values. Most of our results are new and reasonably well understood theoretically.
Nuclear Data Sheets for A = 129
2014, Nuclear Data SheetsThe experimental nuclear spectroscopic data for known nuclides of mass number 129 (Ag, Cd, In, Sn, Sb, Te, I, Xe, Cs, Ba, La, Ce, Pr, Nd, Pm, Sm) have been evaluated and presented together with adopted properties for levels and γ rays. This evaluation represents a revision of the previous one 18 years ago by Y. Tendow (1996Te01). Extensive new data have become available for many nuclides in the intervening years, although, no data are available for excited states in 129Pm and 129Sm, and for 129Ag and 129Cd, only limited information is available for the g.s. and isomers. The decay schemes of 129Ag, 129Pm and 129Sm are unknown, and those for 129Cd, 129In, 129Ce, 129Pr and 129Nd are incomplete. Many γ rays and extended level schemes have been reported for the ground state and isomer decays of 129Ba to 129Cs, yet the adopted set of intensities in this evaluation originate from a brief paper in an annual laboratory report. There remain several unplaced gamma rays, coupled with ambiguity about division of intensities amongst the two activities of 129Ba with nearly the same half-lives. Isomerism is expected in 129Pr, but there is no confirmed identification. Low-lying level structure in 129Nd, including identification of a possible third long-lived isomer in this nuclide, remains uncertain.
The spin-parity assignments of (5/2+) for the ground state and (7/2−) for an isomer at 107.6 keV in 129Ce are assigned based on strong support from systematics and band configurations, yet this result is in contradiction with the quadrupole interaction hyperfine structure measurement which favors 9/2− over 7/2− for the isomer, consequently 7/2+ for the ground state. Direct measurements of spins of ground state and isomer of 129Ce are needed to settle this issue. Confirmed spins and parities of the ground state and isomer of 129La are also lacking. Assignments in this work are mainly based on systematics of decoupled structures. A direct measurement of ground state spin of 129La will also be desirable.
Recommended data presented in this work supersede those in previous NDS evaluations of A=129 nuclides published by 1996Te01, 1983Ha46 and 1972Ho55.
Nuclear data sheets for A=129
1996, Nuclear Data SheetsAbstract:The 1983 evaluation of A = 129 (83Ha46) has been updated using experimental decay and reaction data received by the cutoff date noted below.
Cutoff Date:All data available before December 31, 1995, have been considered for inclusion in this evaluation.
General Policies and Organization of Material:See the January issue of Nuclear Data Sheets.
Acknowledgments:The author would like to thank the staff of the Nuclear Data Center, Japan Atomic Energy Research Institute, for their support. The many useful comments and suggetions by the reviewer and Editor-in-Chief, are gratefully appreciated. I also thank T. Tamura for his helpful comments, and Y. Kidachi for her aid in the preparation of this evaluation.
Transition probabilities in neutron deficient odd cesium and xenon nuclei
1987, Nuclear Physics, Section ASix half-lives and upper limits of three half-lives of excited levels in 125, 127, 129Cs and 123, 125Xe have been measured. Some multipole mixing ratios of involved transitions have been determined. Reduced transition probabilities have been deduced and compared with single-particle estimates and with published theoretical values, in particular from IBFA calculations. B(M1) rates for transitions in odd-N Xe isotopes are also discussed in connection with the problem of l-forbidden transitions.
Nuclear Data Sheets for A = 129
1983, Nuclear Data SheetsThe experimental results from various decays and reactions for the A=129 mass chain have been compiled and evaluated. Adopted values for the level and decay properties are tabulated. Inconsistencies and discrepancies are noted.
Triaxial shape and onset of high-spin bands in <sup>129</sup>Ba
1977, Nuclear Physics, Section AHigh-spin states in 129Ba have been studied by the 120Sn(12C, 3n)129Ba reaction. The onset of a system of bands parallel to the yrast band is observed. The negative parity states () break up into two substructures based upon the lowest states. In addition to the system, a new positive parity structure is seen which is built on the . The results are in qualitative agreement with the triaxial core model.