119756253
R&D status of a large-aperture hybrid avalanche photo-detector
This paper reports on the R&D status of a large-aperture Hybrid Avalanche Photo-Detector (HAPD). We have developed a 13-inch aperture HAPD and its readout system. The HAPD is a photo-detector expected to replace the photomultiplier tube (PMT) in next-generation imaging water Cherenkov detectors such as Hyper Kamiokande. We will present the recent progress made in readout system development. The readout system involves a fast sampling device. The sampling depth (number of cells) has been extended to 256 from 64 in order to measure longer waveform length. The variation in AC gain is now fixed and the input analog bandwidth improved.
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.
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.
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.
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.
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.
120551306
Experimental Search for Kaonic Nuclear Bound States in the 4He(stopped K-,n) Reaction
We made an experimental search for deeply bound kaonic nuclear states ppnK - in 4 He(stopped K - , n) reaction. The experiment is performed in September and October 2002 and the analysis is in progress. The experimental procedure and the present status of the analysis are described.
117564651
Formation of sigma hypernuclei from K̄ absorption at rest (observation of a candidate for the LS doublet)
Pions detected from K− reactions in (CH)n (plastic scintillator) tar reveals a sharp peak at a pion momentum ‐185 MeV/c which is indicative of the Σ+→nπ+ decay. This peak is a candidate for a P3/2‐ P1/2 doublet Σ− hypernucleus. (AIP)
122803940
Secondary charged beam lines at the J-PARC hadron experimental hall
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.
123376999
Development of a super-fluid 4He target system for an experimental search for nuclear K¯ states
Abstract A super-fluid He 4 target system has been successfully developed to experimentally search for deeply bound K ¯ nuclei. From the experimental requirements, the amount of material around the liquid-helium target was drastically suppressed by using two approaches. One was to utilize the properties of super-fluid helium of extremely high thermal conductivity and low vapor pressure. The other was to develop a thin-walled CFRP vacuum chamber and a PET-based target cell. The wall thickness of the CFRP vacuum chamber was only 0.9 mm with the inner diameter of 310 mm. The dimensions of the target cell were 200 mm inner diameter and 150 mm length with the volume of 4.7 l, and it equipped 75 μ m thick beam windows made of a PET film. The present target system achieved a temperature of 1.3 K, and was stably operated throughout the experiment with the operational pressure below 40 mbar and a liquid-helium consumption rate of 45 l / day .