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Sökning: WFRF:(Mey S.)

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1.
  • Schael, S, et al. (författare)
  • Precision electroweak measurements on the Z resonance
  • 2006
  • Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
  • Forskningsöversikt (refereegranskat)abstract
    • We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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  • Eversmann, D., et al. (författare)
  • New Method for a Continuous Determination of the Spin Tune in Storage Rings and Implications for Precision Experiments
  • 2015
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 115:9
  • Tidskriftsartikel (refereegranskat)abstract
    • A new method to determine the spin tune is described and tested. In an ideal planar magnetic ring, the spin tune-defined as the number of spin precessions per turn-is given by nu(s) = gamma G (gamma is the Lorentz factor, G the gyromagnetic anomaly). At 970 MeV/c, the deuteron spins coherently process at a frequency of approximate to 120 kHz in the Cooler Synchrotron COSY. The spin tune is deduced from the up-down asymmetry of deuteron-carbon scattering. In a time interval of 2.6 s, the spin tune was determined with a precision of the order 10(-8), and to 1 x 10(-10) for a continuous 100 s accelerator cycle. This renders the presented method a new precision tool for accelerator physics; controlling the spin motion of particles to high precision is mandatory, in particular, for the measurement of electric dipole moments of charged particles in a storage ring.
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6.
  • Guidoboni, G., et al. (författare)
  • How to Reach a Thousand-Second in-Plane Polarization Lifetime with 0.97-GeV/c Deuterons in a Storage Ring
  • 2016
  • Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 117:5
  • Tidskriftsartikel (refereegranskat)abstract
    • We observe a deuteron beam polarization lifetime near 1000 s in the horizontal plane of a magnetic storage ring (COSY). This long spin coherence time is maintained through a combination of beam bunching, electron cooling, sextupole field corrections, and the suppression of collective effects through beam current limits. This record lifetime is required for a storage ring search for an intrinsic electric dipole moment on the deuteron at a statistical sensitivity level approaching 10(-29) e cm.
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7.
  • Guidoboni, G., et al. (författare)
  • Connection between zero chromaticity and long in-plane polarization lifetime in a magnetic storage ring
  • 2018
  • Ingår i: Physical Review Accelerators and Beams. - : American Physical Society. - 2469-9888. ; 21:2
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper, we demonstrate the connection between a magnetic storage ring with additional sextupole fields set so that the x and y chromaticities vanish and the maximizing of the lifetime of in-plane polarization (IPP) for a 0.97-GeV/c deuteron beam. The IPP magnitude was measured by continuously monitoring the down-up scattering asymmetry (sensitive to sideways polarization) in an in-beam, carbontarget polarimeter and unfolding the precession of the IPP due to the magnetic anomaly of the deuteron. The optimum operating conditions for a long IPP lifetime were made by scanning the field of the storage ring sextupole magnet families while observing the rate of IPP loss during storage of the beam. The beam was bunched and electron cooled. The IPP losses appear to arise from the change of the orbit circumference, and consequently the particle speed and spin tune, due to the transverse betatron oscillations of individual particles in the beam. The effects of these changes are canceled by an appropriate sextupole field setting.
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  • Hempelmann, N., et al. (författare)
  • Locking the Spin Precession in a Storage Ring
  • 2017
  • Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 119:1
  • Tidskriftsartikel (refereegranskat)abstract
    • This Letter reports the successful use of feedback from a spin polarization measurement to the revolution frequency of a 0.97 GeV= c bunched and polarized deuteron beam in the Cooler Synchrotron (COSY) storage ring in order to control both the precession rate (approximate to 121 kHz) and the phase of the horizontal polarization component. Real time synchronization with a radio frequency (rf) solenoid made possible the rotation of the polarization out of the horizontal plane, yielding a demonstration of the feedback method to manipulate the polarization. In particular, the rotation rate shows a sinusoidal function of the horizontal polarization phase (relative to the rf solenoid), which was controlled to within a 1 standard deviation range of sigma= 0.21 rad. The minimum possible adjustment was 3.7 mHz out of a revolution frequency of 753 kHz, which changes the precession rate by 26 mrad/s. Such a capability meets a requirement for the use of storage rings to look for an intrinsic electric dipole moment of charged particles.
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9.
  • Hempelmann, N., et al. (författare)
  • Phase measurement for driven spin oscillations in a storage ring
  • 2018
  • Ingår i: Physical Review Accelerators and Beams. - : American Physical Society. - 2469-9888. ; 21:4
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper reports the first simultaneous measurement of the horizontal and vertical components of the polarization vector in a storage ring under the influence of a radio frequency (rf) solenoid. The experiments were performed at the Cooler Synchrotron COSY in Julich using a vector polarized, bunched 0.97 GeV/c deuteron beam. Using the new spin feedback system, we set the initial phase difference between the solenoid field and the precession of the polarization vector to a predefined value. The feedback system was then switched off, allowing the phase difference to change over time, and the solenoid was switched on to rotate the polarization vector. We observed an oscillation of the vertical polarization component and the phase difference. The oscillations can be described using an analytical model. The results of this experiment also apply to other rf devices with horizontal magnetic fields, such as Wien filters. The precise manipulation of particle spins in storage rings is a prerequisite for measuring the electric dipole moment (EDM) of charged particles.
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10.
  • Saleev, A., et al. (författare)
  • Spin tune mapping as a novel tool to probe the spin dynamics in storage rings
  • 2017
  • Ingår i: Physical Review Accelerators and Beams. - : American Physical Society. - 2469-9888. ; 20:7
  • Tidskriftsartikel (refereegranskat)abstract
    • Precision experiments, such as the search for electric dipole moments of charged particles using storage rings, demand for an understanding of the spin dynamics with unprecedented accuracy. The ultimate aim is to measure the electric dipole moments with a sensitivity up to 15 orders in magnitude better than the magnetic dipole moment of the stored particles. This formidable task requires an understanding of the background to the signal of the electric dipole from rotations of the spins in the spurious magnetic fields of a storage ring. One of the observables, especially sensitive to the imperfection magnetic fields in the ring is the angular orientation of stable spin axis. Up to now, the stable spin axis has never been determined experimentally, and in addition, the JEDI collaboration for the first time succeeded to quantify the background signals that stem from false rotations of the magnetic dipole moments in the horizontal and longitudinal imperfection magnetic fields of the storage ring. To this end, we developed a new method based on the spin tune response of a machine to artificially applied longitudinal magnetic fields. This novel technique, called spin tune mapping, emerges as a very powerful tool to probe the spin dynamics in storage rings. The technique was experimentally tested in 2014 using polarized deuterons stored in the cooler synchrotron COSY, and for the first time, the angular orientation of the stable spin axis at two different locations in the ring has been determined to an unprecedented accuracy of better than 2.8 mu rad.
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  • Margolskee, Alison, et al. (författare)
  • IMI - oral biopharmaceutics tools project - evaluation of bottom-up PBPK prediction success part 1 : Characterisation of the OrBiTo database of compounds
  • 2017
  • Ingår i: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987 .- 1879-0720. ; 96, s. 598-609
  • Tidskriftsartikel (refereegranskat)abstract
    • Predicting oral bioavailability (F-oral) is of importance for estimating systemic exposure of orally administered drugs. Physiologically-based pharmacokinetic (PBPK) modelling and simulation have been applied extensively in biopharmaceutics recently. The Oral Biopharmaceutical Tools (OrBiTo) project (Innovative Medicines Initiative) aims to develop and improve upon biopharmaceutical tools, including PBPK absorption models. A large-scale evaluation of PBPK models may be considered the first step. Here we characterise the OrBiTo active pharmaceutical ingredient (API) database for use in a large-scale simulation study. The OrBiTo database comprised 83 APIs and 1475 study arms. The database displayed a median logP of 3.60 (2.40-4.58), human blood-to-plasma ratio of 0.62 (0.57-0.71), and fraction unbound in plasma of 0.05 (0.01-0.17). The database mainly consisted of basic compounds (48.19%) and Biopharmaceutics Classification System class II compounds (55.81%). Median human intravenous clearance was 16.9 L/h (interquartile range: 11.6-43.6 L/h; n = 23), volume of distribution was 80.8 L (54.5-239 L; n = 23). The majority of oral formulations were immediate release (IR: 87.6%). Human Foral displayed a median of 0.415 (0.203-0.724; n = 22) for IR formulations. The OrBiTo database was found to be largely representative of previously published datasets. 43 of the APIs were found to satisfy the minimum inclusion criteria for the simulation exercise, and many of these have significant gaps of other key parameters, which could potentially impact the interpretability of the simulation outcome. However, the OrBiTo simulation exercise represents a unique opportunity to perform a large-scale evaluation of the PBPK approach to predicting oral biopharmaceutics.
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  • Oláh, János, et al. (författare)
  • Lineage sorting by parameres in Limnephilinae subfamily (Trichoptera): with description of a new tribe, new genera and new species
  • 2019
  • Ingår i: Opuscula Zoologica Instituti Zoosystematici et Oecologici Universitatis Budapestinensis. - 0237-5419 .- 2063-1588. ; 50:S1, s. 3-98
  • Tidskriftsartikel (refereegranskat)abstract
    • The discovery of the new Agaphylax genus with unique paramere organisation has initiated our lineage sorting oftribes by parameres in the Limnephilinae subfamily applying the principles and procedures of fine phenomics in order toestablish transformation series of the polarized plesiomorphy-apomorphy character states for each limnephiline genera.According to the extraordinary high diversity the paramere that is the stimulatory and titillating structure of the phallic organis a speciation supertrait. This adaptive trait is directly involved in the processes of reproductive isolation and diverging assubtle initial split of lineages producing the incipient sibling species in the recent past of contemporary speciation processes.Contrary, the drastic divergence of the Agaphylax plated paramere is much older, similarly to the many-spined parameres ofthe Hesperophylacini tribe. It has been initiated by drastic combined and synchronous external and internal stochastic effects,processed in ancestral sexual integrative adaptation as well as organised and fixed in older and deeper coalescence events andappears as a character with tribe ranking potential. To open a wider perspective, a systemic relational analysis is required inthe future including other adaptive or neutral character transformation series, due to the burden of taxonomic incongruencesgrounded by chimerism in stochastic genetic reticulation. Traits of species are mixed products coming from various sources.Only character combinations can and ought to be analysed in terms how to classify taxa. We have polarized eight genitaliccharacters additional to parameres for a future analysis of the potential of character combinations.Limnephilinae subfamily is composed of Limnephilini, Chilostigmatini, Chaetopterygini, Stenophylacini and Hesperophylacinitribes and here we established the new Agaphylacini tribe. Based on parameres we have delineated taxa in lineagesorting and described two new genera: Fogophylax gen. nov., Simaphylax gen. nov. and fourteen new species: Anaboliaalsoja, A. hepehupa, Asynarchus kimaros, Limnephilus kerekes, L. maghrebensis, L. oblos, Homophylax beges, H. coros,Chaetopteroides plackovicensis, C. rilaensis, Allogamus ketpar, Platyphylax beshkovi, Pycnopsyche letova and P. telea spp.nov. The by-product of this survey is a world atlas of paramere drawings for the entire Limnephilinae subfamily.
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