121191011
The KLOE tracking chamber
Measuring ϵ′ϵ in the kaon complex with the KLOE detector at DAΦNE, the Frascati φ-factory, poses non-trivial problems to the tracking system. The solution adopted by the KLOE collaboration is a single cell drift chamber, non-conventional for both its huge dimensions and for the gas mixture. He-based gas mixtures are characterized by a slow, non saturated drift velocity and by a low electron yield. The R & D activity reported here shows however that binary He mixtures possess the necessary characteristics in terms of stability of operation, cell efficiency, spatial resolution.
110466342
Performance and Aging Studies of BaBar Resistive Plate Chambers
The BaBar detector is currently operating nearly 200 Resistive Plate Chambers (RPCs), constructed as part of an upgrade of the forward endcap muon detector in 2002. Although the average RPC efficiency remains high, numerous changes in the RPC performance (increased currents and rates) have been observed. A few of the highest rate RPCs have suffered efficiency losses of more than 15%. Several types of efficiency loss have been observed. Tests with humidified gas have shown that some of the lost efficiency is recoverable. However, efficiency losses in the highest rate regions have not yet improved with humid gases.
16384620
CKM-UT Angles: Mixing And CP Violation at the B Factories
We review the experimental status of the angles of the Unitarity Triangle of the CKM matrix, as measured by the BABAR and Belle experiments. The B Factories have demonstrated since the beginning of this decade that CP violation in the B meson system is consistent with the Standard Model (SM) description in terms of the complex phase in the three-by-three Cabibbo-Kobayashi-Maskawa (CKM) matrix. With one single phase, the SM predicts clear patterns for quark mixing and CP violations, to be satisfied by all processes.
56098294
Review of measurements of the angles of the CKM matrix from the BaBar experiment
Experimental results on CP violation measurements in the B meson system from the BABAR experiment at the PEP-II asymmetric B Factory are reviewed.
109329842
Improved Particle Identification Using Cluster Counting in a Full-Length Drift Chamber Prototype
Single-cell prototype drift chambers were built at TRIUMF and tested with a ~210MeV/c beam of positrons, muons, and pions. A cluster-counting technique is implemented which improves the ability to distinguish muons and pions when combined with a traditional truncated-mean charge measurement. Several cluster-counting algorithms and equipment variations are tested, all showing significant improvement when combined with the traditional method. The results show that cluster counting is a feasible option for any particle physics experiment using drift chambers for particle identification. The technique does not require electronics with an overly high sampling rate. Optimal results are found with a signal smoothing time of ~5ns corresponding to a ~100MHz Nyquist frequency.
120063494
High precision limited streamer drift tubes
Abstract A tracking telescope employing six layers of Al drift tubes 50 cm long, with diameter d = 3 cm and wall thickness 500 μm, has been built and successfully operated with a 40% Ar-60% iC 4 H 10 gas mixture at atmospheric pressure. The tube cells, with a 100 μm thick CuBe wire strung along the axis, enter streamer mode operation at V = 4.6 kV, and feature full efficiency and local resolution of ≤60 μm.
120709377
Measurement of B-meson semileptonic decay
Using the Columbia University-Stony Brook detector we have measured the production of energetic electrons (E>1 GeV) in e/sup +/e/sup -/ annihilations in the center-of-mass energy range 10.4 to 11.4 GeV. We observe an enhanced electron signal at the UPSILON'''(4S) resonance, which we interpret as evidence for the ..beta.. decay of a new flavor of quark, b, bound within a new flavor meson, B. We derive a branching ratio for B..-->..Xe..nu.. of (13.6 +- 2.5 +- 3)%. The observed energy spectrum of the electrons favors the decay b..-->..ce..nu.. over b..-->..uev.
124699225
Total cross-section measurement at the ISR
SummaryWe present the first results of an experiment at the CERN intersecting storage rings, which measures the total cross-section in proton-proton collisions. The equivalent laboratory momenta are 291, 496, 1068 and 1480 GeV/c. We have made a direct measurement of αT as the ratio between the total interaction rate and the machine luminosity. The present paper gives a detailed description of the experimental apparatus and of the analysis procedure. We find that αT increases by about 10% in the energy region studied.RiassuntoSi presentano i primi risultati di un esperimento agli anelli di accumulazione per protoni del CERN, che misura la sezione d'urto totale delle collisioni protone-protone. Gli impulsi equivalenti nel laboratorio sono di 291, 496, 1068 e 1480 GeV/c. Si è eseguita una misura diretta di αT come rapporto fra frequenza totale di interazione e luminosità della macchina. Questo articolo dà una descrizione dettagliata dell'apparato sperimentale e del procedimento di analisi. Si trova che αT aumenta di circa il 10% nell'intervallo di energia studiato.РезюмеМы предлагаем первые результаты эксперимента в ЦЕРНе на встречных накопительных пучках. В эксперименте проводилось измерение полного поперечного сечения в протон-протонных соударениях. Эквивалентный лабораторный импульс составляет 291, 496, 1068 и 1480 ГэВ/с. Мы провели прямое измерение αT как отношения между полной интенсивностью взаимодействия и светимостью машины. В этой работе приводится подробное описание экспериментальной аппаратуры и анализ методики. Мы обнаружили, что αT возрастает на 10% в исследованной области энергий.
117089603
Measurements of the A2- and A2+ Mass Spectra
126286321
Observation of the Upsilon''' at CESR
110772906
The use of waveform digitizers with drift chambers for D0
Abstract A prototype drift chamber cell with good space resolution, d E d x , and two particle separation has been constructed. A 100 MHz, 11 bit waveform digitizer readout scheme has been used for the tests.