Gamma-ray emission from 134Ce and levels in 134La

The decay of ¹³⁴Ce to doubly odd ¹³⁴La has been studied using Ge(Li) and Si(Li) photon detectors. Samples of the ¹³⁴Ce(75.9 h)- ¹³⁴La(6.67 min) have been produced by ≈ 800 MeV proton bombardment of Pr foils in LAMPF, followed by chemical and mass separation. To increase the sensitivity (by up to a factor ≈ 50) for detection of ¹³⁴Ce γ-rays in the presence of the interfering ¹³⁴La activity, the ¹³⁴Ce-¹³⁴La samples were loaded onto a HDEHP column and the ¹³⁴La eluted off continuously. Gamma-ray singles and γ-γ coincidence measurements were made using the ¹³⁴Ce activity remaining on the column as the source. Some 32 γ-rays, ranging in energy up to 355 keV, are observed to be associated with this decay. Approximately 30 of these have been fitted into a level scheme for ¹³⁴La with excited states at energies of 31, 54, 93, 136 or 148, 162, 187, 150 or 205, 252, 294 and 355 keV. Only limits can be set for the spin and parity values of each of these states. The observation of γ-rays with energies up to 355 keV indicates that the previously reported values of ≈ 0.1 MeV for the ¹³⁴Ce electron-capture decay energy, inferred from the K-electron capture probability, are incorrect.     

Werteverteilung von Zetafunktionen

Ohne Zusammenfassung     

The asymptotics of nonexpansive iterations

Let D be a closed subset of a Banach space X and T: D → D a nonexpansive mapping. Conditions are given (on the space X) for T to satisfy the following property of ergodic type: $\text{{T}{}^{\mathrm{n}}\text{x}\text{n}\text{}}$ converges (either weakly or strongly) to a vector v. Rather unexpectedly, D is not assumed to be convex, nor is I – T assumed to satisfy any range condition. In addition, it is shown that ?v is the unique point of least norm in the closure of R(I – T) if and only if I – T satisfies a certain range condition at infinity. Several interesting applications to accretive operator and nonlinear semigroup theory are also included.     

Buchbesprechungen

Ohne Zusammenfassung     

Properties of single-particle states in the 208Pb region

The properties of single-particle states in the ²⁰⁸Pb region are obtained by subtracting from the empirical values the dressing effects of the multipole particle-hole and pairing phonons. Use is made of the particle-vibration formalism. Single-particle energies, one-body transfer spectroscopic factors and effective quadrupole charges are examined within this framework.     

Asymptotic behavior of solutions to nonlinear Volterra integral equations

A class of operator Riccati integral equations is associated with a factorization problem in a certain Banach algebra. Recent results concerning factorization in this algebra are used to obtain existence, uniqueness, and continuous dependence results for the Riccati equations.     

“Stable” selenenic acids

Two of the stable selenenic acids reported in the literature are actually other materials.     

A limit theorem for projections

The main purpose of this paper is to establish a limit theorem for convex combinations of linear projections. We also include nonlinear extensions as well as several applications.