First results from an aging test of a prototype RPC for the LHCb Muon System

Recent results of an aging test performed at the CERN Gamma Irradiation Facility on a single--gap RPC prototype developed for the LHCb Muon System are presented. The results are based on an accumulated charge of about 0.45 C/cm$^2$, corresponding to about 4 years of LHCb running at the highest background rate. The performance of the chamber has been studied under several photon flux values exploiting a muon beam. A degradation of the rate capability above 1 kHz/cm$^2$ is observed, which can be correlated to a sizeable increase of resistivity of the chamber plates. An increase of the chamber dark current is also observed. The chamber performance is found to fulfill the LHCb operation requirements.Comment: 6 pages, 9 figures, presented at the International Workshop on Aging Phenomena in Gaseous Detectors'', DESY-Hamburg (Germany), October 200

New results from an extensive aging test on bakelite Resistive Plate Chambers

We present recent results of an extensive aging test, performed at the CERN Gamma Irradiation Facility on two single--gap RPC prototypes, developed for the LHCb Muon System. With a method based on a model describing the behaviour of an RPC under high particle flux conditions, we have periodically measured the electrode resistance R of the two RPC prototypes over three years: we observe a large spontaneous increase of R with time, from the initial value of about 2 MOhm to more than 250 MOhm. A corresponding degradation of the RPC rate capabilities, from more than 3 kHz/cm2 to less than 0.15 kHz/cm2 is also found.Comment: 6 pages, 7 figures, presented at Siena 2002, 8th Topical Seminar on Innovative Particle and Radiation Detectors 21-24 October 2002, Siena, Ital

Performance of the Muon Identification at LHCb

The performance of the muon identification in LHCb is extracted from data using muons and hadrons produced in J/\psi->\mu\mu, \Lambda->p\pi and D^{\star}->\pi D0(K\pi) decays. The muon identification procedure is based on the pattern of hits in the muon chambers. A momentum dependent binary requirement is used to reduce the probability of hadrons to be misidentified as muons to the level of 1%, keeping the muon efficiency in the range of 95-98%. As further refinement, a likelihood is built for the muon and non-muon hypotheses. Adding a requirement on this likelihood that provides a total muon efficiency at the level of 93%, the hadron misidentification rates are below 0.6%.Comment: 17 pages, 10 figure

Measurement of the front-end dead-time of the LHCb muon detector and evaluation of its contribution to the muon detection inefficiency

A method is described which allows to deduce the dead-time of the front-end electronics of the LHCb muon detector from a series of measurements performed at different luminosities at a bunch-crossing rate of 20 MHz. The measured values of the dead-time range from 70 ns to 100 ns. These results allow to estimate the performance of the muon detector at the future bunch-crossing rate of 40 MHz and at higher luminosity

Performance of the LHCb muon system with cosmic rays

The LHCb Muon system performance is presented using cosmic ray events collected in 2009. These events allowed to test and optimize the detector configuration before the LHC start. The space and time alignment and the measurement of chamber efficiency, time resolution and cluster size are described in detail. The results are in agreement with the expected detector performance.Comment: Submitted to JINST and accepte

Performance of the LHCb muon system

The performance of the LHCb Muon system and its stability across the full 2010 data taking with LHC running at ps = 7 TeV energy is studied. The optimization of the detector setting and the time calibration performed with the first collisions delivered by LHC is described. Particle rates, measured for the wide range of luminosities and beam operation conditions experienced during the run, are compared with the values expected from simulation. The space and time alignment of the detectors, chamber efficiency, time resolution and cluster size are evaluated. The detector performance is found to be as expected from specifications or better. Notably the overall efficiency is well above the design requirementsComment: JINST_015P_1112 201

Determination of CP and CPT violation parameters in the neutral kaon system using the Bell-Steinberger relation and data from the KLOE experiment

We present an improved determination of the CP and CPT violation parameters Re(epsilon) and Im(delta) based on the unitarity condition (Bell-Steinberger relation) and on recent results from the KLOE experiment. We find Re(epsilon) = (159.6 \pm 1.3)10^-5 and Im(delta) = (0.4 \pm 2.1)10^-5, consistent with no CPT violation.Comment: Submitted to JHE

Measurement of hadronic cross section and preliminary results on the pion form factor using the radiative return at DAPHNE

In the fixed energy environment of the $e^{+}e^{-}$ collider DA$\Phi$NE, KLOE can measure the cross section of the process $e^{+}e^{-} \to$ hadrons as a function of the hadronic system energy using the radiative return. At energies below 1 GeV, $e^{+}e^{-} \to \rho \to \pi^{+}\pi^{-}$ is the dominating hadronic process. We report here on the status of the analysis for the e^{+}e^{-} \to \ppg channel, which allows to obtain a preliminary measurement of the pion form factor using an integrated luminosity of $\sim73 pb^{-1}$.Comment: Invited talk at the Seventh International Workshop on Tau Lepton Physics (TAU02-WE07), Santa Cruz, Ca, USA, Sept 2002, 9 pages, LaTeX, 9 eps figure

Measurements of the Absolute Branching Ratios for the Dominant KL Decays, the KL Lifetime, and Vus with the KLOE Detector

From a sample of about 10^9 Phi mesons produced at DAFNE, we have selected KL mesons tagged by observing KS->pi+pi- decays. We present results on the major KL branching ratios, including those of the semileptonic decays needed for the determination of Vus. These branching ratio measurements are fully inclusive with respect to final-state radiation. The KL lifetime has also been measured.Comment: Submitted to Phys. Lett.