Explore the vast range of titles available.

The PEPITES profiler is a novel beam diagnostic tool that utilizes secondary electron emission (SEE) designed for precise and low-disturbance profiling of charged particle beams. Reducing the monitor WET (Water Equivalent Thickness) allows to minimize the disturbance on the beam, extending the PEPITES usage to lower energies and to farther monitor-target distance applications. This study compares the performances of two detector configurations: the original In-axis anode design, featuring a parallel electron collection electric field, and the upgraded Off-axis anode design, which offers a reduced WET, but with a non-parallel field. Results show that the Off-axis design provides accurate measurements, unaffected by the modified field. These improvements confirm the PEPITES profiler as a promising tool for high-precision beam diagnostics for hadron-therapy.

Simulation of orientational coherent effects via Geant4 beam manipulation of high-and very-high-energy particle beams is a hot topic in accelerator physics. Coherent effects of ultra-relativistic particles in bent crystals allow the steering of particle trajectories thanks to the strong electrical field generated between atomic planes. Recently, a collimation experiment with bent crystals was carried out at the CERN-LHC, paving the way to the usage of such technology in current and future accelerators. Geant4 is a widely used object-oriented tool-kit for the Monte Carlo simulation of the interaction of particles with matter in high-energy physics. Moreover, its areas of application include also nuclear and accelerator physics, as well as studies in medical and space science. We present the first Geant4 extension for the simulation of orientational effects in straight and bent crystals for high energy charged particles. The model allows the manipulation of particle trajectories by means of straight and bent crystals and the scaling of the cross sections of hadronic and electromagnetic processes for channeled particles. Based on such a model, an extension of the Geant4 toolkit has been developed. The code and the model have been validated by comparison with published experimental data regarding the deflection efficiency via channeling and the variation of the rate of inelastic nuclear interactions.

ATF2 is a final-focus test beam line which aims to focus the low emittance beam from the ATF damping ring to a vertical size of about 37 nm and to demonstrate nanometer level beam stability. Several advanced beam diagnostics and feedback tools are used. In December 2008, construction and installation were completed and beam commissioning started, supported by an international team of Asian, European, and U.S. scientists. The present status and first results are described.

The production rates of \\({\\mathrm{D}}^{*\\pm}\\), \\({\\mathrm{D}}_{\\rm{s}}^{* \\pm}\\), \\({\\mathrm{D}}^{\\pm}\\), \\({\\mathrm{D}}^0 / \\bar{{\\mathrm{D}}}^0\\), \\({\\mathrm{D}}_{\\rm{s}}^{\\pm}\\), and \\(\\Lambda_{\\rm c}^{+}/{\\bar{\\Lambda}}_{\\rm c}^{-}\\) in \\({\\rm Z} \\rightarrow {\\mathrm c} \\bar{{\\mathrm c}}\\) decays are measured using the LEP I data sample recorded by the ALEPH detector. The fractional energy spectrum of the \\({\\mathrm{D}}^{*\\pm}\\) is well described as the sum of three contributions: charm hadronisation, b hadron decays and gluon splitting into a pair of heavy quarks. The probability for a c quark to hadronise into a \\({\\mathrm{D}}^{*+}\\) is found to be \\(f({\\mathrm c} \\to{\\mathrm{D}}^{*+}) = 0.233 \\pm 0.010 \\mathrm{(stat.)} \\pm 0.011\\mathrm{(syst.)}\\). The average fraction of the beam energy carried by \\({\\mathrm{D}}^{*\\pm}\\) mesons in \\({\\rm Z} \\to{\\rm c \\bar c}\\) events is measured to be \\({\\langle X_E ({\\mathrm{D}}^{*\\pm}) \\rangle}_{{\\mathrm c} \\bar{{\\mathrm c}}} =0.4878 \\pm 0.0046 \\mathrm{(stat.)} \\pm 0.0061 \\mathrm{(syst.)}.\\) The \\({\\mathrm{D}}^{*\\pm}\\) energy and the hemisphere mass imbalance distributions are simultaneously used to measure the fraction of hadronic Z decays in which a gluon splits to a \\({\\mathrm c} \\bar{{\\mathrm c}}\\) pair: \\(\\bar{n}_{\\mathrm{g} \\to{\\mathrm c}\\bar{{\\mathrm c}}} = (3.23 \\pm 0.48 \\mathrm{(stat.)} \\pm 0.53 \\mathrm{(syst.)})\\%.\\) The ratio of the Vector/(Vector+Pseudoscalar) production rates in charmed mesons is found to be \\(P_V = 0.595\\pm0.045\\). The fractional decay width of the Z into \\({\\mathrm c}\\bar{{\\mathrm c}}\\) pairs is determined from the sum of the production rates for various weakly decaying charmed states to be \\({\\rm R_c} =0.1738 \\pm 0.0047{\\rm (stat.)} \\pm 0.0116 {\\rm (syst.)}.\\)

Inclusive branching ratios involving b to tau transitions are measured in approximately four million hadronic Z decays collected by the ALEPH detector at LEP. The fully-inclusive branching ratio b -> tau nu X and the semi-inclusive branching ratio b -> tau nu D*+/- X are measured to be (2.43 +/- 0.20 +/- 0.25)% and (0.88 +/- 0.31 +/- 0.28)%, in agreement with the standard model predictions. Upper limits on the branching fractions b -> tau nu and b -> s nu nubar are set to 8.3 10**-4 and 6.4 10**-4 at the 90\\%~C.L. These results allow a 90\\% C.L. lower limit of 0.40 (GeV/c**2)**-1 to be set on the tan(beta)/mH+/- ratio, in the framework of type-II two-Higgs-doublet models.

The anomalous weak dipole moments of the $\\tau$ lepton are measured in a data sample collected by ALEPH from 1990 to 1995 corresponding to an integrated luminosity of 155~pb$^{-1}$. Tau leptons produced in the reaction $e^+ e^- \\rightarrow \\tau^+ \\tau^-$ at energies close to the ${\\rm Z}$ mass are studied using their semileptonic decays to $\\pi$, $\\rho$, $a_1 \\rightarrow \\pi 2\\pi^0$ or $a_1 \\rightarrow 3 \\pi$. The real and imaginary components of both the anomalous weak magnetic dipole moment and the CP-violating anomalous weak electric dipole moment, $ {\\rm Re}\\,\\mu_{\\tau}$, ${\\rm Im}\\,\\mu_{\\tau}$, ${\\rm Re}\\,d_{\\tau}$ and ${\\rm Im}\\,d_{\\tau}$, are measured simultaneously by means of a likelihood fit built from the full differential cross section. No evidence of new physics is found. The following bounds are obtained (95\\% CL): $|{\\rm Re}\\, \\mu_{\\tau} | 1.14 \\times 10^{-3}$, $|{\\rm Im}\\, \\mu_{\\tau} | 2.65 \\times 10^{-3}$, $|{\\rm Re}\\, d_{\\tau} | 0.91 \\times 10^{-3}$, and $|{\\rm Im}\\, d_{\\tau} | 2.01 \\times 10^{-3}$.

Hadronic Z decay data taken with the ALEPH detector at LEP1 are used to measure the three-jet rate as well as moments of various event-shape variables. The ratios of the observables obtained from b-tagged events and from an inclusive sample are determined. The mass of the b quark is extracted from a fit to the measured ratios using a next-to-leading order prediction including mass effects. Taking the first moment of the \\(y_3\\) distribution, which is the observable with the smallest hadronization corrections and systematic uncertainties, the result isThe measured ratio is alternatively employed to test the flavour independence of the strong coupling constant for b and light quarks.

The properties of the Z resonance are measured from the analysis of 4.5 million Z decays into fermion pairs collected with the Aleph detector at LEP. The data are consistent with lepton universality. The resonance parameters are measured to be \\(M_{\\rm Z}=(91.1885 \\pm 0.0031){\\rm GeV}/c^2\\), \\(\\Gamma_{\\rm Z}= (2.4951 \\pm 0.0043)\\) GeV, \\(\\sigma^0_{\\rm had}=(41.559 \\pm 0.058)\\) nb and, combining the three lepton flavours, \\(R_{\\ell}= 20.725\\pm 0.039\\). The corresponding number of light neutrino species is \\(N_{\\nu}=2.983\\pm0.013\\) and the strong coupling constant is \\(\\alpha_s(M_{\\rm Z}) = 0.114\\pm{0.004} \\pm 0.002_{\\rm{QCD}} +\\,0.005\\,\\log_{10}\\left[\\frac{M_{\\rm H}}{150\\,{\\rm GeV}/c^2}\\right]\\,\\). The lepton pair forward-backward asymmetry is measured to be \\({\\rm A}_{\\rm FB}^{0, \\ell}=0.0173 \\pm 0.0016\\) from which the effective weak mixing angle is derived: \\(\\sin^2\\theta_{\\rm eff}^{\\rm lept} = 0.23089\\pm 0.00089\\). The measurement of the leptonic width \\(\\Gamma_{\\ell\\ell}=84.02\\pm0.15\\) MeV leads to a determination of the effective \\(\\rho\\) parameter \\(\\rho_{\\rm eff}^{\\rm lept} = 1.0064 \\pm 0.0018\\). The data support the Standard Model and favour a light Higgs.

The polarisation of \\(\\tau\\)'s produced in Z decay is measured using 160 pb\\(^{-1}\\) of data accumulated at LEP by the ALEPH detector between 1990 and 1995. The variation of the polarisation with polar angle yields the two parameters \\({\\cal A}_e = 0.1504 \\pm 0.0068 \\) and \\({\\cal A}_{\\tau} = 0.1451 \\pm 0.0059\\) which are consistent with the hypothesis of e-\\(\\tau\\) universality. Assuming universality, the value \\({\\cal A}_{e\\mbox{-}\\tau} = 0.1474 \\pm 0.0045\\) is obtained from which the effective weak mixing angle \\(\\sin^2{\\theta_{\\mathrm{W}}^{\\mathrm{eff}}} =0.23147 \\pm 0.00057 \\) is derived.

Data from \\({\\rm e^+e^-}\\) annihilation into hadrons, taken with the ALEPH detector at the Z resonance, are analyzed. The four-jet rate is studied as a function of the resolution parameter and compared to next-to-leading order calculations combined with resummation of large logarithms. Angular correlations in four-jet events are measured and compared to next-to-leading order QCD predictions. With these observables two different measurements are performed. In a first analysis the strong coupling constant is measured from the four-jet rate yielding \\(\\alpha_s(M_{\\mathrm Z}) = 0.1170 \\pm 0.0001 ({\\rm stat}) \\pm 0.0013 ({\\rm sys})\\) . In a second measurement the strong coupling constant and the QCD colour factors are determined simultaneously from a fit to the four-jet rate and the four-jet angular correlations, giving \\(\\alpha_s(M_{\\rm Z}) = 0.119 \\pm 0.006 ({\\rm stat}) \\pm 0.026 ({\\rm sys})\\)\\(C_{\\rm A} = 2.93 \\pm 0.14 ({\\rm stat}) \\pm 0.58 ({\\rm sys})\\)\\(C_{\\rm F} = 1.35 \\pm 0.07 ({\\rm stat}) \\pm 0.26 ({\\rm sys})\\) in good agreement with the expectation from QCD.