No abstract

On the basis of the maximum-entropy principle, the usual definition of temperature is extended to quantal systems. Entropy, specific heats, and state equations are evaluated for bounded (i.e. , spinorial systems) and unbounded operators (i.e. , electromagnetic field systems).

Level schemes for~~R b and 9~Sr are proposed based on the study of the P decay of S~Kr and 9~Rb, respectively. The samples mexe obtained using on-line mass-separation techniques applied to~3 5U fission products. y-, P-, and x-ray singles spectra, as mell as (y, y} and (P, y} coincidence spectra, mere taken with Ge(Li} and Si(I i} detectors. Internal-conversion coefficients mere determined for several transitions and the half-lives for the first two levels in Gab and 9~Sr mere measured. In viem of the observed parity change between lorn-lying excited states and the ground state in 9~3b the possibility of deformations to explain this level structure is discussed.

We extend a nonlinear dynamical equation, proposed a few years ago by S. Weinberg to test a possible breakdown in the linearity of Quantum Mechanics, by introducing antihermitian terms (linear and nonlinear) allowing irreversible evolution. Applying the new equation to a two-level atom, we verify that for a particular situation the antihermitian terms lead exactly to the nonlinear Bloch equations obtained in the neoclassical theory of spontaneous emission proposed by Stroud and Jaynes, which do not exhibit pure spontaneous emission. Lifting that particularization we gain additional antihermitian terms in the nonlinear Bloch equation that take care of the pure spontaneous emission problem. In view of this new terms we discuss whether they are meaningful as a “correction” to linear Quantum Mechanics.