18761544
Study of top-quark reconstruction with LCD Fast Simulation
We report the study of top-quark reconstruction in $e^+e^- \to t\bar{t}$ events at a 500 GeV linear collider using the LCD Fast Simulator. The final states of 6 jets as well as 4 jets and lepton are used. In order to reconstruct the jets, the performance of charged and neutral cluster separation are studied. We compare top-quark reconstruction for the LCD Small and LCD Large detectors, including the effect of varying the calorimeter granularity.
16601897
Mechanisms affecting performance of the BaBar resistive plate chambers and searches for remediation
The BaBar experiment at PEPII relies on the instrumentation of the flux return (IFR) for both muon identification and KL detection. The active detector is composed of resistive plate chambers (RPCs) operated in streamer mode. Since the start of operation the RPCs have suffered persistent efficiency deterioration and dark current increase problems. The ‘‘autopsy’’ of bad BaBar RPCs revealed that in many cases uncured linseed oil droplets had formed on the inner surface of the Bakelite plates, leading to current paths from oil ‘‘stalagmites’’ bridging the 2mm gap. In this paper, a possible model of this ‘‘stalagmite’’ formation and its effect on the dark current and efficiency of RPC chambers is presented. Laboratory test results strongly support this model. ARTICLE IN PRESS *Corresponding author. Tel.: +1-609-258-4391; fax: +1-609-258-6360. E-mail address: changguo@princeton.edu (C. Lu). 0168-9002/03/$ see front matter r 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0168-9002(03)01292-0 Based upon this model we are searching for solutions to eliminate the unfavorable effect of the oil stalagmites. The lab tests show that the stalagmite resistivity increases dramatically if exposed to the air, an observation that points to a possible way to remedy the damage and increase the efficiency. We have seen that flowing an oxygen gas mixture into the chamber helps to polymerize the uncured linseed oil. Consequently, the resistivity of the bridged oil stalagmites increases, as does that of the oil coating on the frame edges and spacers, significantly reducing the RPC dark currents and low-efficiency regions. We have tested this idea on two chambers removed from BaBar because of their low efficiency and high dark current. These test results are reported in the paper, and two other remediation methods also mentioned. We continue to study this problem, and try to find new treatments with permanent improvement. r 2003 Elsevier Science B.V. All rights reserved.
13435498
Study of top-quark production and decay vertices with LCD fast simulation
We report a study of top-quark reconstruction in e+e−→tt events at a 500 GeV linear collider using the LCD Fast simulator. The initial study of top-quark anomalous couplings is also reported. The final states of 4 jets and lepton as well as 6 jets are used. Using the 4 jets and lepton final state, we estimate the preliminary sensitivities for form factors at the γ/Z0tt vertex. In the 6 jets reconstruction, we show abilities of the top-quark charge identification and the c-quark tagging in W decays.
56000332
PROGRESS OF DESIGN STUDY OF INTERACTION REGION QUADRUPOLES FOR THE SUPER-KEKB
For KEKB upgrade, we are studying the design of the final focus quadrupoles to achieve very small β-functions at the interaction point (IP). For each beam, the final beam focusing system consists of quadrupole-doublet of the superconducting and permanent magnets. In this paper, the design progress of final focusing magnets is reported.
15071400
LCD ROOT simulation and analysis tools
The North American Linear Collider Detector group has developed a simulation program package based on the ROOT system. The package consists of Fast simulation, the reconstruction of the Full simulated data, and physics analysis utilities.
54880563
Design and Status of the SuperKEKB Accelerator Control Network System
We have upgraded the accelerator control network system for SuperKEKB, the next generation B-factory experiment in Japan. The designed network system has the higher performance based on the wider bandwidth data transfer, and more reliable and redundant configuration. For the SuperKEKB beamline construction and accelerator components maintenance, we have installed the new wireless network system consists with the Leaky Coaxial (LCX) cable antennas and collinear antennas into the 3 km circumference accelerator tunnel. In this paper, we describe the design and current status of the SuperKEKB accelerator control network system.
9987198
Measurement of the kaonic hydrogen x-ray spectrum.
The DEAR (DAPhiNE exotic atom research) experiment measured the energy of x rays emitted in the transitions to the ground state of kaonic hydrogen. The measured values for the shift epsilon and the width Gamma of the 1s state due to the K(-)p strong interaction are epsilon(1s)=-193 +/- 37 (stat) +/- 6 (syst) eV and Gamma(1s)=249 +/- 111 (stat) +/- 30 (syst) eV, the most precise values yet obtained. The pattern of the kaonic hydrogen K-series lines, K(alpha), K(beta), and K(gamma), was disentangled for the first time.
16001859
Phase transition of color superconductivity and cooling behavior of quark stars
We discuss color superconductivity and its effect on the cooling behavior of strange quark stars. The neutrino emissivity and specific heat of quark matter are calculated within the BCS theory. In the superconducting phase, the emissivity decreases and causes suppression of the cooling rate. It is shown that the phase transition leads to a sudden discontinuous suppression of the cooling rate in cooperation with the specific heat.
120897225
L-series X-ray yields of kaonic 3He and 4He atoms in gaseous targets
The SIDDHARTA experiment measured X-rays from kaonic helium atoms using, for the first time, gaseous 3He and 4He targets. Clear patterns of the L-series X-rays of kaonic 3He and 4He atoms were observed. By using accurate Monte Carlo simulations, the absolute yields of these X-ray transitions were determined to be Y(3d → 2p) = 25.0−5.8+6.7% for 3He (0.96 g/l), Y(3d → 2p) = 23.1−4.2+6.0% for 4He (1.65 g/l), and Y(3d → 2p) = 17.2−9.5+2.6% for 4He (2.15g/l). In addition, the yields Y (nd → 2p), with n > 3 were also determined. The measured yields provide valuable information for understanding the cascade processes of kaonic helium atoms as a function of the target density.
22969599
Conceptual design of a radial vane silicon tracker for a new measurement of the muon anomalous magnetic moment g-2 and electric dipole moment at J-PARC
A new measurement of the anomalous magnetic moment (g-2) and electric dipole moment (EDM) of the positive muon at J-PARC is proposed. In this experiment, we plan to use a radial vane silicon detector for detecting muon decay positrons. Specification and design study of the detector has been promoted. In order to determine detector parameters, we are developing simulation and positron track reconstruction tools. First version of those using Geant4 and Hough transform method in ideal condition was constructed. We are improving these tools close to real condition and the multi-track finding efficiency has been investigated. In this paper, we report the progress of the studies in simulation and track finding tools for the optimization of the detector parameters.
120408377
Solving the kaonic-helium puzzle
We have measured the Balmer-series x-rays of kaonic 4He atoms using large-area silicon drift x-ray detectors (SDDs) in order to study the low-energy -nucleus strong interaction. The energy of the 3d → 2p transition was determined to be 6467 ± 3(stat) ± 2(syst) eV. The resulting strong-interaction energy-level shift is in agreement with theoretical calculations, thus eliminating a long-standing discrepancy between theory and experiment.