L. von Lindern

The reactions π−p → ϱon and K−p → K∗ o(890)n at 11.2 GeV/c

We report here the results of a spark chamber experiment in which the reactions π−p → ϱon and K−p → K∗0(890)n were studied at 11.2 GeV/c incident beam momentum. The cross sections are determined to be σ(ϱo) = 128 ± 16 μb and σ[K{rmo(890)] = 53 ± 8 μb. Differential cross sections and values of the spin density matrix elements are given for both reactions. An enhancement in the (π−π+) invariant mass distribution is observed at a mass of 946 MeV.

Observation of the μ−μ+ decay mode of the η° meson

Abstract The rare decay mode of the η° meson into two muons has been observed. The branching ratio for this decay mode is calculated using production cross-sections from other experiments, and the result is compared with theoretical predictions.

High-resolution measurement of circadian periodicities in Acetabularia.

Well-expressed endogenous circadian rhythms in Acetabularia acetabulum were spectrally analyzed and recorded in time-period distributions. The stability of the circadian periods under constant conditions and their changes could be monitored continually in step sizes close to the circadian period length. The resolution of period estimates of the circadian component was increased by a factor of approximately 4-10 by adapting analyzed interval lengths to full period sizes of the corresponding main component. Methodological aspects of the applied algorithms are discussed by means of examples that measure the temperature dependency of the circadian period.

Leptonic decay branching ratio of the ρ meson

Abstract We report here on preliminary results obtained from observing the reactions π − + LiH → μ + + μ − + … π − + LiH → π + + π − + … using 11.2 GeV c incident π− mesons from the CERN Proton Synchroton. From these reactions we have determined the branching ratio Γ(ρ → μμ) Γ(e → ππ).

The reaction π−p → K+K−n between 988 and 100 MeV invariant KK mass

Abstract We report here on the results of an optical spark chamber experiment studying the reaction π − p → K + K − at 11.04 GeV/ c π − momentum. The apparatus measured the K + K − system over all decay orientations up to a mass of 1100 MeV and | t | ⩽ 0.5 (GeV/ c ) 2 . The observed mass spectrum comprises a superposition of a slowly varying S-wave and P-wave, the φ-resonance, and a small bump at 1063 MeV. The spin-density matrix elements of the K + K − system are presented and discussed. The φ-mass and width were determined to be M = 1018 −0.35 +0.5 MeV, Γ = 3.3 −0.9 +1.5 MeV.