Production of A20and ω1 (1675) in the reaction π−p → π+π−π0n at 12 and 15 GeV/c

Data on the reaction π^?p → π⁺π^?π⁰ have been taken at 12 and 15 GeV/c with the CERN Omega multiparticle spectrometer. In a 3-pion partial-wave analysis strong production of $\text{A}{}_2{}^0\text{(1310)}\text{and}\text{ω}{}^1\text{(1675)}$ is observed. Total and differential cross sections are determined and density matrix elements presented as a function of t in the t- and s-channel frames. The energy dependence of A₂⁰ production is studied, and a comparison of $\text{ω(780),}\text{A}{}_2{}^0\text{(1310)}\text{and}\text{ω}{}^1\text{(1675)}$ production is made.     

Wideline NMR studies of polyacrylonitrile

NMR linewidth studies of molecular motion in several polyacrylonitrile samples have been carried out. The motional transition temperature is found in the 105–124°C. range and depends upon polymerization conditions. In addition, the thermal activation energy for the motional process underlying this transition was evaluated at 16.4 kcal./mole. Finally, measurement of the transition temperature for one of the specimens in three different physical states (bulk, spun only, and spun and drawn with a ratio of 3:1), revealed that no change in the transition temperature was effected by either spinning or drawing.     

Wideline NMR studies of oriented nylon 66

Wideline NMR techniques have been applied to both singly and doubly oriented specimens of nylon 66. Variations in the spectra obtained are observed for different orientations of the specimens relative to the applied field. These variations demonstrate that the zigzag chain axis is essentially parallel to the draw direction and that motion occurs in all of the sample. The motion is of two types: random in the mobile regions and rotation of segments about the chain axis in the rigid regions.     

ω Production in the reaction π−p → π+π−π0n at 8 and 12 GeV/c

The reaction π^?p → ωn has been studied at 8 and 12 GeV/c incident momenta with the CERN Omega spectrometer using a neutron time of flight trigger. The differential cross sections and the ω-decay density matrix elements are presented as functions of the momentum transfer squared ?t in the range of 0.02 to 0.80 GeV². The data are used to evaluate the intercept and slope of both the natural and unnatural parity exchange trajectories. Regge exchange amplitude factorisation tests involving the reaction πN → ωN are investigated.     

K+n elastic and charge-exchange scattering between 430 and 940 MeV/c

Elastic and charge-exchange K⁺n differential cross sections have been measured from K⁺d interactions from 430 to 940 MeV/c using spark chambers and scintillation counters. The data have been compared with existing results and in an accompanying paper have been included with other measurements in a phase-shift analysis.     

Highly stereoselective addition of organometallic reagents to N-tert-butanesulfinyl imines derived from 3- and 4-substituted cyclohexanones

Addition of alkyl or aryl Grignard reagents to N-sulfinyl imines derived from 3- and 4-substituted cyclohexanones proceeds with good yields and with excellent diasteroselectivity. The selectivity of the reaction is controlled by the ring substituent rather than the sulfinyl group stereochemistry, and therefore racemic tert-butanesulfinamide can be employed.     

Observation of an x-ray vortex

Phase singularities are a ubiquitous feature of waves of all forms and represent a fundamental aspect of wave topology. An optical vortex phase singularity occurs when there is a spiral phase ramp about a point phase singularity. We report an experimental observation of an optical vortex in a field consisting of 9-keV x-ray photons. The vortex is created with an x-ray optical structure that imparts a spiral phase distribution to the incident wave field and is observed by use of diffraction about a wire to create a division-of-wave-front interferometer.     

Ter-body intermediates in the gas phase: reaction of ionized enols with tert-butanol

In the gas phase, the CH2CHOH.+ enol radical cation 1 as well as its higher homologues CH3CHCHOH.+ 2 and (CH3)2CCHOH.+ 3, undergo exactly the same sequence of reactions with tert-butanol, leading to the losses of isobutene, water and water plus alkene. Fourier transform ion cyclotron resonance (FT-ICR) experiments using labeled reactants as well as ab initio calculations show that independent pathways can be proposed to explain the observed reactivity. For ion 1, taken as the simplest model, the first step of the reaction is formation of a proton bound complex which gives, by a simple exothermic proton transfer, the ter-body intermediate [CH2CHO., H2O, C(CH3)3+]. This complex, which was shown to possess a significant lifetime, is the key intermediate which undergoes three reactions. First, it can collapse to yield tert-butylvinyl ether with elimination of water. Second, by a regiospecific proton transfer, this complex can isomerize into three different ter-body complexes formed of water, isobutene and ionized enol. Within one of these complexes, which does not interconvert with the others, elimination of isobutene leads to the formation of a solvated enol ion. Within the others, a cycloaddition-cycloreversion process can proceed to yield the ionized enol 3 (loss of water and ethylene channel).