16314864
Electron identification using the TOPAZ detector at TRISTAN
Abstract We present an electron-identification method using the time-projection chamber and the lead-glass calorimeter in the TOPAZ detector system. Using this method we have achieved good electron identification against hadron backgrounds over a wide momentum range in the hadronic events produced by both single-photon exchange and two-photon processes. Pion-rejection factors and electron efficiencies were 163 and 68.4% for high- P T electrons and 137 and 42.7% for low- P T electrons in the single-photon-exchange process, and 8600 and 36.0% for the two-photon process, respectively.
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.
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.
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.
55994477
BEAM BACKGROUND AND MDI DESIGN FOR SUPERKEKB/BELLE-II
The Belle experiment, operated at the asymmetric electron-positron collider KEKB, had accumulated a data sample with an integrated luminosity of more than 1 ab −1 before the shutdown in June 2010. We have started upgrading both the accelerator and the detector, SuperKEKB and Belle-II, to achieve the target luminosity of 8 × 10 35 cm −2 s −1 . With the increased luminosity, the beam background will be severe. The development of MachineDetector Interface (MDI) design is crucial to cope with the increased background and protect Belle-II detector. We will present the estimation of impact from each beam background sources at SuperKEKB and our countermeasures for them, such as collimators to stop Touschek-scattered beam particles, Tungsten shield to protect inner detectors from shower particles, and dedicated beam pipe design around interaction point to stop synchrotron radiation, etc.
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.
119744703
STRANGE MULTI-BARYON AND KAONIC ATOMS
123421510
Method of probing inner-structure of geophysical substance with the horizontal cosmic-ray muons and possible application to volcanic eruption prediction
Abstract One potential use of cosmic-ray muons arriving nearly horizontally along the earth is a probe of the inner-structure of a gigantic geophysical substance, such as a volcanic mountain. A simple detection system comprising a plastic scintillator hodoscope which is expandable to a larger scale was developed. The first successful measurement of the inner-structure of Mt. Tsukuba is described. The future perspective of the application of the present method towards the prediction of volcanic eruption is discussed.
133597393
Search for the deeply bound $K^-pp$ state via the $^3$He($K^-,n)$ reaction at $p_{K^-}$=1 GeV/$c$
An experiment to search for the Kpp bound state was performed via the in-flight He(K, n) reaction at θ n = 0 ◦ using 5.3 × 10 kaons at 1 GeV/c at the J-PARC hadron experimental facility. In the neutron missing-mass spectrum, no significant peak was observed in the region corresponding to Kpp binding energy larger than 80 MeV, where a bump structure was reported in the Λp final state in different reactions. Mass-dependent upper limits of the production cross section for the state isotropically decaying into Λp were determined at 95% confidence level to be (30–180), (70–250), and (100–270) μb/sr, for the natural widths of 20, 60, and 100 MeV, respectively.
123071679
Regge trajectories of baryons in the MIT bag model
Abstract We investigate Regge trajectories of baryons in the MIT bag model. It is shown that the energy spectra shown by the trajectories can be described fairly well by the stringlike solutions of the bag model. In particular, three strings with one junction and three ends can explain the delta trajectory better than one string with two ends. The three ends occupied by each quark are assumed to be an equilateral triangle configuration in our calculations.
120900736
Kaonic nitrogen X-ray transition yields in a gaseous target
Abstract The first measurement of the yields of three kaonic nitrogen X-ray transitions, using the DEAR (DAΦNE Exotic Atom Research) setup at the DAΦNE collider of Frascati, is reported. The yields are 41.5±8.7(stat.)±4.1(sys.)% for the n =7→6 transition, 55.0±3.9(stat.)±5.5(sys.)% for the n =6→5 transition and 57.4±15.2(stat.)±5.7(sys.)% for the n =5→4 transition at a density ρ =3.4 ρ NTP . By using the experimental yields in an atomic cascade calculation, a 1 to 3% K-shell electron population in the n =6 level was deduced.