We report on a recent set of measurements of the transverse wakefields from longitudinally tapered collimators. The measurements were performed with a low-emittance 1.19 GeV beam in the SLAC linac by ...inserting a collimator aperture into the beam path and reconstructing the vertical deflection of the beam as a function of the vertical position of the aperture. Each collimator in the experiment was designed to present a relatively large transverse impedance and to minimize the impedance from other contributions such as resistivity. In addition, the collimator parameters were chosen to provide some insight into the scaling of the transverse geometric wakefield as a function of the collimator’s geometry. A description of the experimental apparatus and the aperture design, the method of data collection and analysis, and a comparison to theoretical and numerical predictions are presented.
Vortex cleaning of fuel tank pressurant gas Biryuk, V. V.; Shimanov, A. A.; Onoprienko, D. A. ...
Vestnik Samarskogo universiteta. Aèrokosmičeskaâ tehnika, tehnologii i mašinostroenie (Online),
07/2015, Letnik:
14, Številka:
1
Journal Article
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One of the problems of space launch vehicle fuel tanks using gas pressure accumulators is dealt with in the article. Helium mixed with gas generator gases is used as a pressure gas accumulator, which ...makes it possible to increase the specific volume of pressurant gas and decrease the mass of the system. Gas generator gas comprises carbon particles that cause fast clogging of the filter, which leads to a contingency and charge pressure drop. The use of soot-cleaning vortex apparatus was suggested for efficient fail-safe operation of the tank pressurization system. Different types of vortex soot- cleaning devices were considered. A reverse-flow cyclone was chosen as the most appropriate type of vortex soot cleaner for a fuel tank pressurization system. The required soot cleaner was designed and its flow part was modeled. A finite element mesh was obtained and boundary conditions were set. Numerical modeling of the soot cleaning process was carried out in a reverse-flow cyclone with the help of ANSYS Fluent. Fields of soot particle distribution and the character of their motion in the reverse-flow cyclone were plotted.
Comparative analysis of heat exchangers of various types is carried out: crossflow, shell- and- tube, plate heat exchangers. Mass- power characteristics of the three types of heat exchangers are ...calculated.
We have developed a new technique for inclusive reconstruction of the energy of B hadrons. The excellent efficiency and resolution of this technique allow us to make the most precise determination of ...the b -quark fragmentation function, using e{sup +}e{sup -}{yields}Z{sup 0} decays recorded in the SLAC Large Detector experiment. We compared our measurement with the predictions of a number of fragmentation models. We excluded several of these models and measured the average scaled energy of weakly decaying B hadrons to be <x{sub B}>=0.714{+-}0.005(stat ){+-}0.007(syst){+-}0.00 2 (model dependence). (c) 2000 The American Physical Society.
AbstractThe full exploitation of the physics potential of a future Linear Collider requires the development of polarised positron beams. A very promising scheme for the technical realisation is the ...use of helical undulators, generating circular polarised photons of several MeV which are then converted in a thin target to longitudinally polarised positrons. The experiment E-166 tests this scheme. It uses the low-emittance 50-GeV electron beam at the Final Focus Test Beam (FFTB) at SLAC, passing through a 1 meter-long helical undulator. The flux and polarisation of the undulator photons as well as the properties of the positrons will be measured and will be compared with simulations.PACS: 12.60.-i Models beyond the standard model – 13.88.+e Polarization in interactions and scattering – 29.27.Hj Polarized Beams – 95.75.Hi Polarimetry
The parity violation parameters A(b) and A(c) of the Zb(b) and Zc(c) couplings have been measured directly, using the polar angle dependence of the polarized cross sections at the Z(0) pole. Bottom ...and charmed hadrons were tagged via their semileptonic decays. Both the electron and muon analyses take advantage of new multivariate techniques to increase the analyzing power. Based on the 1993-1998 SLD sample of 550,000 Z(0) decays produced with highly polarized electron beams, we measure A(b) = 0.919+/-0.030(stat)+/-0.024(syst), and A(c) = 0.583+/-0.055(stat)+/-0.055(syst).
We have made the first measurement of the double-inclusive B/B energy distribution in e+e− annihilations, using a sample of 400000 hadronic Z0-decay events recorded in the SLD experiment at SLAC ...between 1996 and 1998. The small and stable SLC beam spot and the CCD-based vertex detector were used to reconstruct B/B-decay vertices with high efficiency and purity, and to provide precise measurements of the kinematic quantities used to calculate the B energies in this novel technique. We measured the B/B energies with good efficiency and resolution over the full kinematic range. We measured moments of the scaled energies of the B and B hadrons vs. the opening angle between them. By comparing these results with perturbative QCD predictions we tested the ansatz of factorisation in heavy-quark production. A recent next-to-leading order calculation reproduces the data.
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