The CDFII Time-Of-Flight Detector and Impact on Beauty Flavor Tagging
The new CDFII detector incorporates a Time-of-Flight detector (TOF), em-ploying plastic scintillator bars and ﬁne-mesh photomultipliers. Since August 2001 the TOF system has been fully instrumented and integrated into the CDFII data acquisition system. With a design goal of 100 ps resolution the TOF system will pro-vide at least two standard deviations separation between K ± and π ± for momenta p < 1 . 6 GeV/c , complementing low momentum particle identiﬁcation by means of the speciﬁc ionization energy loss measured in the drift chamber. We describe the design of the TOF detector and discuss the current status of its calibration and initial performances. Finally we review the expected impact of the TOF detector in the ﬂavor tagging of neutral B S meson.
Front end electronics for the CDF-II Time-of-Flight system
A Time-of-Flight detector (TOF) has been added to the CDF-II experiment to provide charged kaon identification primarily for neutral B meson flavor determination. The TOF front end electronics system has 432 channels and is designed to run at the 7.58 MHz bunch crossing rate in CDF. The electronics contributes less than 25 ps to the anticipated TOF timing resolution of 100 ps, which is dominated by photon statistics. This paper describes the design and implementation of the electronics as well as the initial in situ performance.
EFFECT OF SAMPLE PREPARATION ON WATER TREE RESISTANCE OF XLPE/SEBS BLENDS
The effects of an aromatic polymer, such as poly[styrene-b-(ethylene-co-butylene)b-styrene] (SEBS), and its preparation processes on water tree resistance, morphology, crystallinity, dielectric constant and dielectric loss tangent of crosslinked polyethylene (XLPE)/SEBS and XLPE/SEBS/ethylene vinyl acetate (EVA) blends were investigated. The XLPE/SEBS samples were characterized by means of differential scanning calorimetry, scanning electron microscopy, dielectric spectral analysis and the accelerated water treeing experiment. The results clearly showed that although SEBS was partially compatible with LDPE and it was dispersed evenly in XLPE matrix, the blends demonstrated excellent dielectric performances, such as dielectric constant and dissipation factor. The crystallinity of XLPE/SEBS blends was decreased with increase in SEBS content and it was further decreased with the addition of EVA. SEBS could effectively improve the water-tree resistance of XLPE and both SEBS and EVA were found to improve the water tree resistance of XLPE synergistically as expected. The differences in sample preparation processes could change the phase morphology and dielectric performance of the blends, and could also influence the dispersion of SEBS in XLPE matrix as well as the crystallinity of the blends. Different preparation processes led to different water tree resistance behaviours of the samples. The improvement of SEBS dispersion in XLPE matrix helped to improve the water tree resistance of XLPE.