Study of e+e−→ppˉe^+e^- \rightarrow p\bar{p} in the vicinity of ψ(3770)\psi(3770)

Using 2917 $\rm{pb}^{-1}$ of data accumulated at 3.773~$\rm{GeV}$, 44.5~$\rm{pb}^{-1}$ of data accumulated at 3.65~$\rm{GeV}$ and data accumulated during a $\psi(3770)$ line-shape scan with the BESIII detector, the reaction $e^+e^-\rightarrow p\bar{p}$ is studied considering a possible interference between resonant and continuum amplitudes. The cross section of $e^+e^-\rightarrow\psi(3770)\rightarrow p\bar{p}$, $\sigma(e^+e^-\rightarrow\psi(3770)\rightarrow p\bar{p})$, is found to have two solutions, determined to be ($0.059\pm0.032\pm0.012$) pb with the phase angle $\phi = (255.8\pm37.9\pm4.8)^\circ$ ($<$0.11 pb at the 90% confidence level), or $\sigma(e^+e^-\rightarrow\psi(3770)\rightarrow p\bar{p}) = (2.57\pm0.12\pm0.12$) pb with $\phi = (266.9\pm6.1\pm0.9)^\circ$ both of which agree with a destructive interference. Using the obtained cross section of $\psi(3770)\rightarrow p\bar{p}$, the cross section of $p\bar{p}\rightarrow \psi(3770)$, which is useful information for the future PANDA experiment, is estimated to be either ($9.8\pm5.7$) nb ($<17.2$ nb at 90% C.L.) or $(425.6\pm42.9)$ nb

Etude des propriétés mécaniques des multicouches métal/céramique

International audienceMultilayers of alternative metal and ceramic (nitrid) present attractive tribological properties. The aim of this study is to correlate the hardness with the structural properties.Multilayers films of Ti-TiN with a period thickness equal 20,10,8,5 and 2.5 nm, were deposited by RF reactive sputtering on silicon substrates with a metallic target. The deposition was done at room temperature for T-TiN.The total and period thickness for all the films, were measured by Grazing X-Ray Reflectometry. The hardness was measured by nanoindention with a Berkovich diamond indentor. For T-TiN the hardness increases with decreasing period thickness to go beyond the rule-of-mixture value for samples with period thickness Lambda less than or equal to 5 nm. The maximum hardness, 1.6 times higher than the rule of mixture value, is obtained for Lambda = 2.5 nm. However a similar tribological behavior was obtain for these two systems. Wear resistance increases when the period thickness decrease and shows a maximun value for the smallest A, superior to those of monolithic layers TiN and Al2O3

Mechanical properties of Al/Al2O3 nanolaminated films: correlation to microstructure

peer reviewedaudience: researcher, professional, studentWear resistance and the hardness of Al/Al2O3 nanolaminated films were investigated in this study. Monolithic films and multilayers were deposited on a silicon substrate with two different substrate temperatures: T-s= 25 degrees C and T-s= -90 degrees C. The period thickness of multilayers was lowering from 40 to 2 nm. From nanoindentation measurements, it appears that the hardness of multilayers has an intermediate value between those of metal (Al) and ceramic (Al2O3). The tribological test was conducted by the pin-on-disc method. The T-s=25 degrees C deposited multilayers, as well as single films, demonstrated poor wear resistance. The best wear resistance was obtained for multilayers deposited at the lowest substrate temperature (T-s= -90 degrees C). The results are ill good agreement with structural characterization. X-ray reflectometry demonstrated that the multilayer character of Al/Al2O3 is more pronounced for T-s= -90 degrees C. (C) 2000 Elsevier Science S.A. All rights reserved

Nanoindentation investigation of Ti/TiN multilayers films

peer reviewedThe hardness of Ti/TiN nanolaminated films is investigated in this study. Monolithic Ti and TiN films and Ti/TiN multilayers were deposited on silicon substrates by radio-frequency sputtering. The period thickness of multilayers was decreased from 20 to 2.5 nm. Grazing x-ray reflectometry showed that the modulation of composition of Ti/TiN multilayers exists for all the period thickness considered. From nanoindentation measurements, we determined the hardness and Young's modulus of multilayers. Hardness increased with decreasing period thickness to go beyond the rule-of-mixture value for samples with period thickness of Lambda less than or equal to 5 nm. The maximum hardness, 1.6 times higher than the value obtained by the rule of mixture, is obtained for Lambda=2.5 nm. Our results are compared to a dislocation-based model previously introduced by Lehoczky. (C) 2000 American Institute of Physics. [S0021-8979(00)09411-1]

Conjugate additions of lithium dialkynylcuprates (RC C)(2)CuLi to activated chromones. Unexpected formation of the 6H-bis 1 benzopyrano 2,3-b : 3',4'-e pyridine system

Lithium dialkynylcuprates [(RCequivalent toC)(2)CuLi], 1a-d, are easily generated and undergo conjugate additions to activated chromones giving 2-alkynylchroman-4-ones 4a-d, 13, 15c,d and 5, however, 1,4-additions to 3 proceed anomalously to give the eneynonitriles 6a-b and the bisbenzopyranopyridine 7