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DIRC Dreams: Research Directions for the Next Generation of Internally Reflected Imaging Counters

Description: Some conceptual design features of the total internally reflecting,imaging Cherenkov counter (DIRC) are described. Limits of the DIRC approach to particle identification, and a few features of alternative DIRC designs, are briefly explored.
Date: August 17, 1999
Creator: Ratcliff, Blair N
Partner: UNT Libraries Government Documents Department

Performance confirmation of the Belle II imaging Time Of Propogation (iTOP) prototype counter

Description: The Bell Detector at the KEKB asymmetric-energy e{sup +}e{sup -} collider performed extremely well, logging an integrated luminosity an order of magnitude higher than the design baseline. With this inverse attobarn of integrated luminosity, time-dependent CP-violation inn the 3rd generation beauty quarks was firmly established, and is now a precision measurement. Going beyond this to explore if the Kobayashi-Maskawa mechanism is the only contributor to quark-mixing, and to interrogate the flavor sector for non-standard model enhancements, requires a detector and accelerator capable of topping this world-record luminosity by more than an order of magnitude. The Belle II detector at the upgraded Super-KEKB accelerator has been designed to meet this highly ambitious goal of operating at a luminosity approaching 10{sup 36} cm{sup -2} s{sup -1}. Such higher event rates and backgrounds require upgrade of essentially all detector subsystems, as well as their readout. Comparing the Belle composite (threshold Aerogel + Time of Flight) particle identification (PID) system with the DIRC employed by BaBar, quartz radiator internal Cherenkov photon detection proved to have higher kaon efficiency and lower pion fake rates. However, because the detector structure and CsI calorimeter will be retained, an improved barrel PID must fit within a very narrow envelope, as indicated in Figure 1. To effectively utilize this space, a more compact detector concept based on the same quartz radiators, but primarily using photon arrival time was proposed. This Time Of Propagation (TOP) counter was studied in a number of earlier prototype tests. Key to the necessary 10's of picosecond single-photon timing has been the development of the so-called SL-10 Micro-Channel Plate Photo-Multiplier Tube (MCP-PMT), which has demonstrated sub-40 ps single photon Transit Time Spread TTS. Further simulation study of this detector concept indicated that a focusing mirror in the forward direction, as well as a modest image ...
Date: October 17, 2011
Creator: Schwartz, Alan; Liu, Yang; Belhorn, Matt; U., /Cincinnati; Browder, Thomas; Varner, Gary et al.
Partner: UNT Libraries Government Documents Department

Time-dependent Dalitz-Plot Analysis of the Charmless Decay B^0 -> K^0S Pi Pi- at BABAR

Description: A time-dependent amplitude analysis of B{sup 0} {yields} K{sub S}{sup 0}{pi}{sup +}{pi}{sup -} decays is performed in order to extract the CP violation parameters of f{sub 0}(980)K{sub S}{sup 0} and {rho}{sup 0}(770)K{sub S}{sup 0} and direct CP asymmetries of K*{sup +}(892){pi}{sup -}. The results are obtained from the final BABAR data sample of (465 {+-} 5)10{sup 6} B{bar B} decays, collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. The time dependent CP asymmetry for f{sub 0}(980)K{sub S}{sup 0} and {rho}{sup 0}(770)K{sub S}{sup 0} are measured to be S(f{sub 0}(980)K{sub S}{sup 0}) = -0.97 {+-} 0.09 {+-} 0.01 {+-} 0.01, and S({rho}{sup 0}(770)K{sub S}{sup 0}) = 0.67 {+-} 0.20 {+-} 0.06 {+-} 0.04, respectively. In decays to K*{sup +}(892){pi}{sup -} the direct CP asymmetry is found to be A{sub CP}(K*{sup {+-}}(892){pi}{sup {-+}}) = -0.18 {+-} 0.10 {+-} 0.04 {+-} 0.00. The relative phases between B{sup 0} {yields} K*{sup +}(892){pi}{sup -} and {bar B}{sup 0} {yields} K*{sup -}(892){pi}{sup +}, relevant for the extraction of the unitarity triangle angle {gamma}, is measured to be {Delta}{phi}(K*(892){pi}) = (34.9 {+-} 23.1 {+-} 7.5 {+-} 4.7){sup o}, where uncertainties are statistical, systematic and model-dependent, respectively. Fit fractions, direct CP asymmetries and the relative phases of different other resonant modes have also been measured. A new method for extracting longitudinal shower development information from longitudinally unsegmented calorimeters is also presented. This method has been implemented as a part of the BABAR final particle identification algorithm. A significant improvement in low momenta muon identification at BABAR is obtained.
Date: October 17, 2009
Creator: Ilic, J
Partner: UNT Libraries Government Documents Department