Multipion production below 1.1 GeV by e+e− annihilation

The production of multipion events by e⁺e^? annihilation has been measured at centre of mass energies 915,990 and 1076 MeV. Both channels e⁺e^?→π⁺π^?π^o and e⁺e^?→π⁺π^?π⁺π^? have been analysed. An energy threshold effect analysed. An energy threshold effect around 919 MeV (m_ω + m_π^o) has been evidenced for the π⁺π^?π^oπ^o channel and the cross section is consistent with the quasi two-body process e⁺e^?→ωπ^o. The cross section for π⁺π^?π⁺π^? is lower by an order of magnitude and increases with the energy.     

New measurements of the radiative decay modes of the φ-meson

The radiative decay models of the φ-meson have been studied: e⁺e^?→φ→ηγ→3γ; e⁺e^?→φ→π^oγ→3γ. Cross sections σ_{φ→ηγ→3γ} and σ_{φ→π^oγ→3γ} have been measured at five energies in the φ-meson energy region and clearly show the φ-resonance in the ηγ → 3γ mode as well as in the π^oγ → 3γ mode. From a Breit-Wigner fit to the experimental data the values of the branching ratios are deduced: B_φ→ηγ = (1.5 ± 0.4) × 10^?2; B_φ→π^oγ = (1.4 ± 0.5) × 10^?3.     

An international intercomparison exercise for total mercury in seawater

Two 30 dm³ coastal seawater samples were collected in September 1983. One was acidified, homogenized and divided among 50 500-cm³ glass ampoules. The second was spiked with 612ng of mercury added as methylmercury chloride, acidified, homogenized and divided among 50 500-cm³ glass ampoules. All these operations were performed under a mercury-free atmosphere. A single sample from each set was sent to each of 37 laboratories; 21 of them submitted their results of a ‘total’ mercury concentation determination. The consensus values and their confidence limits are 6.0 ± 1.6 and 24.2 ± 2.8 ng dm^?3 for the natural and the spiked samples respectively. Eleven laboratories reported reliable quantitative results (within ± 2SD ) for the natural (unspiked) sample, and 12 for the spiked sample. In addition, ten laboratories give sets of results within ± 2SD of the consensus values. Storage for up to four months of methylmercury spiked samples with 1.4% nitric acid (0.3 mol dm^?3) at room temperature is, alone, an unsuitable treatment for releasing mercury from its monomethyl compounds.