Engineering topics
Liu, C.
Publications and source records attributed to Liu, C..
Optics measurement and correction during beam acceleration in the Relativistic Heavy Ion Collider
To minimize operational complexities, setup of collisions in high energy circular colliders typically involves acceleration with near constant β-functions followed by application of strong focusing quadrupoles at the interaction points (IPs) for the final beta-squeeze. At the Relativistic Heavy Ion Collider (RHIC) beam acceleration and optics squeeze are performed simultaneously. In the past, beam optics correction at RHIC has taken place at injection and at final energy with some interpolation of corrections into the acceleration cycle. Recent measurements of the beam optics during acceleration and squeeze have evidenced significant beta-beats which if corrected could minimize undesirable emittance dilutions and maximize the spin polarization of polarized proton beams by avoidance of higher-order multipole fields sampled by particles within the bunch. In this report the methodology now operational at RHIC for beam optics corrections during acceleration with simultaneous beta-squeeze will be presented together with measurements which conclusively demonstrate the superior beam control. As a valuable by-product, the corrections have minimized the beta-beat at the profile monitors so reducing the dominant error in and providing more precise measurements of the evolution of the beam emittances during acceleration.
Absolute beam emittance measurements at RHIC using ionization profile monitors
In the past, comparisons between emittance measurements obtained using ionization profile monitors, Vernier scans (using as input the measured rates from the zero degree counters, or ZDCs), the polarimeters and the Schottky detectors evidenced significant variations of up to 100%. In this report we present studies of the RHIC ionization profile monitors (IPMs). After identifying and correcting for two systematic instrumental errors in the beam size measurements, we present experimental results showing that the remaining dominant error in beam emittance measurements at RHIC using the IPMs was imprecise knowledge of the local beta functions. After removal of the systematic errors and implementation of measured beta functions, precise emittance measurements result. Also, consistency between the emittances measured by the IPMs and those derived from the ZDCs was demonstrated.
Decoupling catalytic activity from biological function of the ATPase that powers lipopolysaccharide transport
Abstract not provided
Measurement of the Branching Fraction B ( Λ c + → p K - π + )
In this work, we present the first model-independent measurement of the absolute branching fraction of the Λ c + → p K - π + decay using a data sample of 978 fb - 1 collected with the Belle detector at the KEKB asymmetric-energy e + e - collider. The number of Λ c + baryons is determined by reconstructing the recoiling D ( * ) - p ¯ π + system in events of the type e + e - → D ( * ) - p ¯ π + Λ c + . Lastly, the branching fraction is measured to be B ( Λ c + → p K - π + ) = ( 6.84 ± 0.24 - 0.27 + 0.21 ) % , where the first and second uncertainties are statistical and systematic, respectively.
Measurement of D 0 - D ¯ 0 mixing and search for indirect C P violation using D 0 → K S 0 π + π - decays
Here, we report a measurement of D 0 - D ¯ 0 mixing parameters and a search for indirect C P violation through a time-dependent amplitude analysis of D 0 → K S 0 π + π - decays. The results are based on 921 fb - 1 of data accumulated with the Belle detector at the KEKB asymmetric-energy e + e - collider. Assuming C P conservation, we measure the mixing parameters x = ( 0.56 ± 0.19 - 0.09 - 0.09 + 0.03 + 0.06 ) % and y = ( 0.30 ± 0.15 - 0.05 - 0.06 + 0.04 + 0.03 ) % , where the errors are statistical, experimental systematic, and systematic due to the amplitude model, respectively. Lastly, with C P violation allowed, the parameters | q / p | = 0.90 - 0.15 - 0.04 - 0.05 + 0.16 + 0.05 + 0.06 and arg ( q / p ) = ( - 6 ± 11 ± 3 - 4 + 3 ) ° are found to be consistent with conservation of C P symmetry in mixing and in the interference between mixing and decay, respectively.
Transverse impedance measurement in RHIC and the AGS
The RHIC luminosity upgrade program aims for an increase of the polarized proton luminosity by a factor 2. To achieve this goal a significant increase in the beam intensity is foreseen. The beam coupling impedance could therefore represent a source of detrimental effects for beam quality and stability at high bunch intensities. For this reason it is essential to quantify the accelerator impedance budget and the major impedance sources, and possibly cure them. In this MD note we summarize the results of the 2013 transverse impedance measurements in the AGS and RHIC. The studies have been performed measuring the tune shift as a function of bunch intensity and deriving the total accelerator machine transverse impedance. For RHIC, we could obtain first promising results of impedance localization measurements as well.
Updated cross section measurement of e + e - → K + K - J / ψ and K S 0 K S 0 J / ψ via initial state radiation at Belle
The cross sections of the processes e + e - → K + K - J / ψ and K S 0 K S 0 J / ψ are measured via initial state radiation at center-of-mass energies between the threshold and 6.0 GeV using a data sample of 980 fb - 1 collected with the Belle detector on or near the Υ ( n S ) resonances, where n = 1 , 2 , … , 5 . The cross sections for e + e - → K + K - J / ψ are at a few pb level and the average cross section for e + e - → K S 0 K S 0 J / ψ is 1.8 ± 0.6 ( stat ) ± 0.3 ( syst ) pb between 4.4 and 5.2 GeV. All of them are consistent with previously published results with improved precision. Furthermore, a search for resonant structures and associated intermediate states in the cross section of the process e + e - → K + K - J / ψ is performed.
Measurement of branching fractions for B -> J / K decays and search for a narrow resonance in the J / final state
Measurement of branching fractions for B \to J/ψηK decays and search for a narrow resonance in the J/ψηfinal state
Study of B 0 → ρ 0 ρ 0 decays, implications for the CKM angle <Φ/mi> 2 and search for other B 0 decay modes with a four-pion final state
Study of B^0 -> rho^0 rho^0 decays, implications for the CKM angle phi_2 and search for other B^0 decay modes with a four-pion final state
Observation of D 0 - D ¯ 0 Mixing in e + e - Collisions
In this work, we observe D 0 - D ¯ 0 mixing in the decay D 0 → K + π - using a data sample of integrated luminosity 976 fb - 1 collected with the Belle detector at the KEKB e + e - asymmetric-energy collider. We measure the mixing parameters x ' 2 = ( 0.09 ± 0.22 ) × 1 0 - 3 and y ' = ( 4.6 ± 3.4 ) × 1 0 - 3 and the ratio of doubly Cabibbo-suppressed to Cabibbo-favored decay rates R D = ( 3.53 ± 0.13 ) × 1 0 - 3 , where the uncertainties are statistical and systematic combined. Our measurement excludes the no-mixing hypothesis at the 5.1 standard deviation level.
Experimental Investigation of Bonding Strength and Residual Stresses in HIP Clad Fuel Plates
Abstract not provided
SIMULTANEOUSLY EFFICIENT LIGHT ABSORPTION AND CHARGE SEPARATION IN WO3/BIVO4 CORE/SHELL NANOWIRE PHOTOANODE FOR PHOTOELECTROCHEMICAL WATER OXIDATION
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Arabidopsis ABCG14 protein controls the acropetal translocation of root-synthesized cytokinins
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