We report a measurement of the ortho-para transition rate in the p mu p molecule. The experiment was conducted at TRIUMF via the measurement of the time dependence of the 5.2 MeV neutrons from muon capture in liquid hydrogen. The measurement yielded an ortho-para rate Lambda op = (11.1 +/- 1.7 +/-(0.9)(0.6)) x 10(4) s(-1), which is substantially larger than the earlier result of Bardin et al. The result has striking implications for the proton's induced pseudoscalar coupling g(p), changing the value of g(p) obtained from the most precise ordinary muon capture measurement from 10.6 +/- 2.7 to 0.8 +/- 2.8, and from the sole radiative muon capture measurement from 12.2 +/- 1.1 to 10.6 +/- 1.2, bringing the latter result closer to theoretical predictions.

We report the first observation of double radiative capture on pionic hydrogen. The experiment was conducted at the TRIUMF cyclotron using the RMC spectrometer and detected gamma-ray coincidences following pi(-) stops in liquid hydrogen. We found the branching ratio for double radiative capture to be [3.05+/-0.27(stat)+/-0.31(syst)]x10(-5). The measured branching ratio and angle-energy distributions support the theoretical prediction of a dominant contribution from the pipi-->gammagamma annihilation mechanism.

We report a search for d * dibaryon production by double-radiative capture on pionic deuterium. The experiment was conducted at the TRIUMF cyclotron using the RMC cylindrical pair spectrometer, and detected γ-ray coincidences following pion stops in liquid deuterium. We found no evidence for narrow dibaryons, and obtained a branching ratio upper limit, BR < 6.7×10 −6 (90% C.L.), for narrow d * production in the mass range from 1920 to 1980 MeV.

Excitation functions for the yields of ten residual nuclides from the ' C+' Ne reaction have been measured over the range E, =11 -33 MeV in steps of 150 keV, using y-ray techniques. The magnitude and energy dependence of the excitation functions for most partial yields, as well as for the total fusion yield, closely resemble those from the ' 0+ "0 system when compared at the same compound-nuclear excitation energy. The total fusion yield exhibits strong anomalies at E, =22.7 and 24. 1 MeV, while the Ne inelastic scattering yield exhibits a strong uncorrelated structure at E, =21.1 MeV. In addition weaker structure is seen at E, =13.6, 16.6, 18.6, and 26.3 MeV in the total fusion yield.The 24.1 MeV resonance corresponds to a characteristic structure in the ' 0+' 0 reaction yields. Both structures appear at the same S excitation energy and are found to be correlated with the transition to a regime of limited fusion. NUCLEAR REACTIONSNe(' C~l; E, =11 -33 MeV; measured excitation functions for production of A =20 -30 reaction products; observed structure at E, =(13.6), 16.6, 18.6, 21.1, 22.7, 24.1, and 26.3 MeV; deduced critical angular momentum for fusion.

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We report a search for low-lying exotic baryons via double radiative capture on pionic hydrogen. The data were collected at the TRIUMF cyclotron using the RMC spectrometer by detecting gamma-ray pairs from pion stops in liquid hydrogen. No evidence was found to support an earlier claim for exotic baryons of masses 1004 and 1044 MeV/c 2 . We obtain upper limits on the branching ratios for double radiative capture via these exotic states of < 3 × 10 −6 and < 4 × 10 −6 respectively.

Inelastic neutron scattering data presented for 2.5-MeV neutrons bombarding 152 Sm evince the direct excitation of rotational 2 + , 4 + , 6 + , and 8 + levels of this deformed nucleus. The measured scattering cross sections for these levels are very much larger than can be ascribed to a statistical model mechanism. Coupled-channels calculations of the inelastic scattering cross sections also fall well below the observed enhancements for the 4 + and 6 + levels.

We report measurements of double radiative capture in pionic hydrogen and pionic deuterium. The measurements were performed with the RMC spectrometer at the TRIUMF cyclotron by recording photon pairs from pion stops in liquid hydrogen and deuterium targets. We obtained absolute branching ratios of (3.02 ± 0.27(stat.) ± 0.31(syst.)) × 10 −5 for hydrogen and (1.42 ± 0.09 0.12 (stat.) ± 0.11(syst.)) × 10 −5 for deuterium, and relative branching ratios of double radiative capture to single radiative capture of (7.68 ± 0.69(stat.) ± 0.79(syst.)) × 10 −5 for hydrogen and (5.44 ± 0.34 0.46 (stat.) ± 0.42(syst.))×10 −5 for deuterium. For hydrogen, the measured branching ratio and photon energy-angle distributions are in fair agreement with a reaction mechanism involving the annihilation of the incident π − on the π + cloud of the target proton. For deuterium, the measured branching ratio and energyangle distributions are qualitatively consistent with simple arguments for the expected role of the spectator neutron. A comparison between our hydrogen and deuterium data and earlier beryllium and carbon data reveals substantial changes in the relative branching ratios and the energy-angle distributions and is in agreement with the expected evolution of the reaction dynamics from an annihilation process in S-state capture to a bremsstrahlung process in P-state capture. Lastly, we comment on the relevance of the double radiative process to the investigation of the charged pion polarizability and the in-medium pion field.