Fundamental irreversibility and the concept of events

It is proposed that the transmutation from possibilities to facts should be introduced as an essential element in fundamental theory. This has no bearing on TCP-invariance. If indeterminism is accepted it leads to a picture of an evolving history formed by individual events and causal ties. In the low density regime it can be compared with the treatment of multiple collisions in quantum field theory.Dedicated to Res Jost and Arthur Wightman, friends for many years and appreciators of unorthodox thought     

Quasiadiabatic solutions of Fokker Planck equations with time-dependent drift and fluctuations coefficients

A systematic algorithm for finding solutions of Fokker Planck systems with time-dependent drift and fluctuation coefficients is developed. The solutions lag behind the adiabatic quasistationary distribution. This delay effect vanishes for slowly varying control parameters. In a first example the evolution of the phase transition from a monostable to a bistable system is treated. There is a fluctuation enhancement and the delay of the probability distribution leads to a transient central peak. In a second example a linear model with time-dependently shifted drift is considered. The introduced approximation scheme reproduces the exact solution already in first order.     

Die Spektren der Neutronen aus den Reaktionen C12(γ,n)C11 und O16(γ,n)O15

The (γ, n)-reactions on carbon and oxygen were studied using the 30,5 MeV brems-strahlung beam of the Heidelberg betatron. The photoneutrons were detected via the recoil protons in a stilbene scintillator. The pulse height spectrum of scintillations produced in the stilbene crystal by the recoil protons is analyzed to yield the incident neutron energy distribution. Theγ-ray and electron background was strongly reduced through pulse shape discrimination. To test the apparatus the spectrum of the neutrons from a Po-α-Be source was measured. The energy spectrum of the photo-neutrons from O¹⁶ shows clearly two peaks at excitation energies of 22,4 and 24,4 MeV also seen in the photo-proton spectra. The energy distribution of the neutrons from C¹² (γ, n) too contains indication of structure already known from the proton spectra from C¹² (γ, p). The derived cross sections of C¹² (γ, n ₀) and O¹⁶ (γ, n ₀) coincide as well in their shape as in their absolute magnitude with the corresponding (γ, p ₀)-cross sections. In both C¹² (γ, n) and O¹⁶ (γ, n)-reaction the neutrons seem to leave the final nucleus mainly in its ground state.