Measurement of the Muon Decay Parameter delta

The muon decay parameter delta has been measured by the TWIST collaboration. We find delta = 0.74964 +- 0.00066(stat.) +- 0.00112(syst.), consistent with the Standard Model value of 3/4. This result implies that the product Pmuxi of the muon polarization in pion decay, Pmu, and the muon decay parameter xi falls within the 90% confidence interval 0.9960 < Pmuxi < xi < 1.0040. It also has implications for left-right-symmetric and other extensions of the Standard Model.Comment: Extended to 5 pages. Referee's comments answere

Measurement of the Michel Parameter ρ\rho in Muon Decay

The TWIST Collaboration has measured the Michel parameter $\rho$ in normal muon decay, $\mu^+ \to e^+ \nu_e \bar{\nu}_{\mu}$. In the Standard Model, $\rho$ = 3/4. Deviations from this value require mixing of left- and right-handed muon and electron couplings in the muon-decay Lagrangian. We find $\rho$ = 0.75080 $\pm$ 0.00044(stat.) $\pm$ 0.00093(syst.) $\pm$ 0.00023, where the last uncertainty represents the dependence of $\rho$ on the Michel parameter $\eta$. This result sets new limits on the $W_L-W_R$ mixing angle in left-right symmetric models.Comment: 4 pages, 3 figures, submitted to PR

Measurement of P_{mu}xi in Polarized Muon Decay

The quantity P_{mu}^{pi}xi, where xi is one of the muon decay parameters and $P_{\mu}^{\pi}$ is the degree of muon polarization in pion decay, has been measured. The value P_{mu}^{pi}xi = 1.0003 +- 0.0006 stat. +- 0.0038 syst. was obtained. This result agrees with previous measurements but is over a factor of two more precise. It also agrees with the Standard Model prediction for P_{mu}^{pi}xi and thus leads to restrictions on left-right symmetric models.Comment: 11 pages, 7 figures, Phys. Rev. D 74, 072007 (2006) Final versio

Effect of Glass Fibers Thermal Treatment on the Mechanical and Thermal Behavior of Polysulfone Based Composites

The effect of thermal treatment of glass fibers (GF) on the mechanical and thermo-mechanical properties of polysulfone (PSU) based composites reinforced with GF was investigated. Flexural and shear tests were used to study the composites&rsquo; mechanical properties. A dynamic mechanical analysis (DMA) and a heat deflection temperature (HDT) test were used to study the thermo-mechanical properties of composites. The chemical structure of the composites was studied using IR-spectroscopy, and scanning electron microscopy (SEM) was used to illustrate the microstructure of the fracture surface. Three fiber to polymer ratios of initial and preheated GF composites (50/50, 60/40, 70/30 (wt.%)) were studied. The results showed that the mechanical and thermo-mechanical properties improved with an increase in the fiber to polymer ratio. The interfacial adhesion in the preheated composites enhanced as a result of removing the sizing coating during the thermal treatment of GF, which improved the properties of the preheated composites compared with the composites reinforced with initial untreated fibers. The SEM images showed a good distribution of the polymer on the GF surface in the preheated GF composites

Measurement of P µ ξ in Polarized Muon Decay

The quantity P π µ ξ, where ξ is one of the muon decay parameters and P π µ is the degree of muon polarization in pion decay, has been measured. The value P π µ ξ = 1.0003±0.0006 (stat.)±0.0038 (syst.) was obtained. This result agrees with previous measurements but is over a factor of two more precise. It also agrees with the Standard Model prediction for P π µ ξ and thus leads to restrictions on left-right symmetric models