First Measurement of a Long-Lived π

The adapted DIRAC experiment at the CERN PS accelerator observed for the first time long-lived hydrogenlike π^{+}π^{-} atoms, produced by protons hitting a beryllium target. A part of these atoms crossed the gap of 96 mm between the target and a 2.1 µm thick platinum foil, in which most of them dissociated. Analyzing the observed number of atomic pairs, n_{A}^{L}=436_{-61}^{+157}|_{tot}, the lifetime of the 2p state is found to be τ_{2p}=(0.45_{-0.30}^{+1.08}|_{tot})×10^{-11} s, not contradicting the corresponding QED 2p state lifetime τ_{2p}^{QED}=1.17×10^{-11} s. This lifetime value is three orders of magnitude larger than our previously measured value of the π^{+}π^{-} atom ground state lifetime τ=(3.15_{-0.26}^{+0.28}|_{tot})×10^{-15} s. Further studies of long-lived π^{+}π^{-} atoms will allow us to measure energy differences between p and s atomic states and so to discriminate between the isoscalar and isotensor ππ scattering lengths with the aim to check QCD predictions.

Observation of π

The observation of hydrogenlike πK atoms, consisting of π^{-}K^{+} or π^{+}K^{-} mesons, is presented. The atoms are produced by 24 GeV/c protons from the CERN PS accelerator, interacting with platinum or nickel foil targets. The breakup (ionization) of πK atoms in the same targets yields characteristic πK pairs, called "atomic pairs," with small relative momenta Q in the pair center-of-mass system. The upgraded DIRAC experiment observed 349±62 such atomic πK pairs, corresponding to a signal of 5.6 standard deviations. This is the first statistically significant observation of the strange dimesonic πK atom.

[Maternal cardiopathy in relation to perinatal morbidity and mortality]. / Mütterliche Kardiopathie im Zusammenhang mit perinataler Morbidität und Mortalität.

Reference is made to pregnancy risks, including spontaneous abortion, prematurity, and foetal retardation, for women with haemodynamically important cardiopathies. The risk may be mitigated by high-continuity extended medical care in centres for cardio-angiopathies of women in pregnancy. Attention should be given in such centres not only to congenital and acquired cardiac defects, but to all circulatory disorders as well as to some diseases of the respiratory system.

[Women with cardio-angiopathies before conception (author's transl)]. / Problematik der Frauen mit Kardioangiopathien in der Präkonzeptionszeit.

Extended medical care for pregnant women with cardio-angiopathies is discussed in this paper. High-continuity follow-up checks should begin in early childhood and conducted also in adult age, prior to conception. Appropriate medical documentation, including radiographs, should be complied well prior to pregnancy, to avoid X-ray examination during gravidity.--Also discussed is dicumarol treatment of pregnant carriers of artificial cardiac valves. Any treatment of cardio-angiopathy should be best timed to periods before conception to the benefit of better family planning. Extended medical care should be persistently implemented with high continuity as an integral part of medical programmes extended by district centres to pregnant women with cardio-angiopathies.