Study of B Decays to Charmonium States: B-->eta(c)K and B --> chi(c0)K

In a sample of 9.66x10(6)B&Bmacr; pairs collected with the CLEO detector we make the first observation of B decays to an eta(c) and a kaon. We measure branching fractions B(B+-->eta(c)K+) = (0.69(+0.26)(-0.21)+/-0.08+/-0.20)x10(-3) and B(B degrees -->eta(c)K degrees ) = (1.09(+0.55)(-0.42)+/-0.12+/-0.31)x10(-3), where the first error is statistical, the second is systematic, and the third is from the eta(c) branching fraction uncertainty. From these we extract the eta(c) decay constant in the factorization approximation, f(eta(c)) = 335+/-75 MeV. We also search for B decays to a chi(c0) and a kaon. No evidence for a signal is found and we set 90% C.L. upper limits: B(B+-->chi(c0)K+)<4.8x10(-4) and B(B degrees -->chi(c0)K degrees )<5.0x10(-4).     

Search for the decay upsilon(1S) --> gammaeta(')

We report on a search for the radiative decay Upsilon(1S)-->gammaeta(') in 61.3 pb(-1) of data taken with the CLEO II detector at the Cornell Electron Storage Ring. Three decay chains were investigated, all involving eta(')-->pi(+)pi(-)eta, followed by eta-->gammagamma, eta-->pi(0)pi(0)pi(0), or eta-->pi(+)pi(-)pi(0). We find no candidate events in any of the three cases and set a combined upper limit of 1.6x10(-5) at 90% C.L., significantly smaller than the previous limit. We compare our result to other radiative Upsilon decays, to radiative J/psi decays, and to theoretical predictions.     

Effect of anisotropy on viscous fingering patterns of polymer solutions in linear Hele-Shaw cells

Viscous fingering patterns of hydroxypropyl methyl cellulose (HPMC) solutions were investigated by forcing air in linear geometry isotropic and anisotropic Hele-Shaw cells as functions of HPMC concentration and injection pressure of air. The resulting patterns depended on the HPMC concentration and the cell anisotropy. The characteristic quantities of pattern growth, such as the finger velocity and the finger width, were evaluated. The finger velocity in the anisotropic linear cell was faster than that in the isotropic one, and the finger velocity and the finger width were well correlated with the pattern morphological changes. (c) 1999 American Institute of Physics.     

Further studies on the ultraviolet graft copolymerization of maleimide by vapor-phase method

Graft copolymerization of maleimide onto polyethylene and ethyl cellulose films by using its sublimation vapor was carried out under ultraviolet irradiation in the presence or absence of air; the effect of air or additives on the grafting reaction and on the nature of the grafted films was investigated. The extent of grafting gradually approached a fixed value, in spite of the continuous ultraviolet irradiation. Air retarded the grafting reaction but did not suppress the reaction nor alter the final extent of grafting. Benzoquinone showed no inhibiting effect on the grafting. The grafted polymaleimide was found to be amorphous, even though ultraviolet irradiation produces a highly crystalline homopolymer in the solid phase as well as in the liquid phase. The results were discussed in comparison with those of the vapor-phase grafting under γ-ray irradiation; the reaction is attributed to the vapor–crystal equilibrium of monomer and to the formation of short-chain crosslinks.     

Gamma rays and neutrons following preequilibrium 165Ho(p, xcnypγ) reactions at Ep = 60 MeV

Neutrons and γ-rays following 60 MeV proton bombardment of ¹⁶⁵Ho were measured in coincidence with discrete γ-rays characteristic of the reaction channels (residual nuclei). The cross sections for the (p, xcnγ) reactions with x = 2–6, the γ-ray multiplicities, and the energy and angular distributions of the emitted neutrons were analyzed in terms of the preequilibrium and equilibrium deexcitation processes. Characteristic behaviours of the preequilibrium process were found in the (p, 2nγ) and (p, 4nγ) reactions where the sum E_T, = ∑^xE_i of the energies E_i of the emitted neutrons was large, while those of the equilibrium process were typical for the (p, 6ny) reaction with small E_T. The reactions are well reproduced by the expression σ. ≈0.35∑_xσ (2, x?2) + 0.4∑_xσ(1, χ?1)+ 0.25∑_xσ(0, x), where σ(n_p, n_c) stands for emission of n_p neutrons at the preequilibrium stage followed by evaporation of n_c neutrons at the equilibrium stage.