We observe a net beam-excess of 8.7±6.3 (stat) ±2.4 (syst) events, above 160 MeV, resulting from the charged-current reaction of νµ and/orνµ on C and H in the LSND detector. No beam related muon background is expected in this energy regime. Within an analysis framework of π 0 → νµνµ, we set a direct upper limit for this branching ratio of Γ(π 0 →νµνµ)/Γ(π 0 →all) < 1.6 × 10 −6 at 90% confidence level.The observation of the decay π 0 → νν would imply new interesting physics. The pion has zero spin and odd intrinsic parity (i.e. J P = 0 − ), and it is represented by a wave function which has the space transformation properties under inversion and rotation of a pseudoscalar. Momentum and angular momentum conservation require that the decay ν andν possess the same helicity. This decay provides an ideal laboratory to search for the pseudoscalar (P) weak interaction, because only the P interaction allows massless neutrinos and antineutrinos with the same helicity in the final state. Furthermore, if the neutrino mass is not zero and the Z 0 couples to the right-handed neutrino with standard weak-interaction strength, the branching ratio (BR) B(π 0 → ν µνµ ) has a maximum value of 5.4 × 10

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A new picosecond lifetime measurement system developed at UNISOR was used to determine the half-life of the well-deformed [Formula: see text] levels in 188Hg and 186Hg. The half-life values were measured to be 204±45 ps in 188Hg and ≤52 ps in 186Hg. The corresponding values of ρ2(E0)×103, obtained from the partial half-lives, were [Formula: see text] and ≥32, respectively. Additionally, the half-lives of the [Formula: see text] levels were determined to be 141±31 ps in 188Hg and 48±27 ps in 186Hg.

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Gamma-ray and conversion electron singles and coincidence spectroscopy have been performed on the decay of 6.2-h '"Cs to levels of '"Xe and 30-h ' Cs to levels of '"Xe. From these data, new levels, transition multipolarities, and spin and parity assignments are derived. The systematic structure of the odd-mass Xe nuclides with 69» N & 81 is shown and the results of various calculations are discussed. Support for the use of relatively weak coupling models to describe these nuclides is enumerated.