[en] The QCAL tile calorimeters of KLOE are two compact detectors placed close to the interaction point and surrounding the focalization quadrupoles. Their purpose is to increase the hermeticity of KLOE calorimetry, improving the rejection of background K_L → π⁰π⁰π⁰ decays, whose photon energies range from 20 to 280 MeV. Each QCAL consists of a sampling structure of lead plates and 1 mm scintillator tiles, with readout via wavelength shifter (WLS) fibers and mesh photomultipliers, arranged in 16 azimuthal sectors. The arrangement of WLS fibres allows measuring the longitudinal position of the showers from TOF. We discuss the design and present first results from cosmic rays tests

[en] We performed a calculation of the energy loss dE/dx and the primary ionization density dN/dx for a charged heavy particle crossing a gas volume as a function of the particle β. We start from the Maxwell equation and using the experimental values of the photo-absorption cross section, we take into account the different material properties. Our calculation of dE/dx is in excellent agreement with the Bethe-Bloch function and in the case of dN/dx we found a relativistic rise and a good agreement with the primary ionization experimental data we compare. We consider the possibility to use primary ionization measure to make the particle identification in the large tracking chambers. (author)

[en] Results on particle identification obtained measuring the primary ionization in a drift chamber operating in a mixture He 80%-CH₄ 20% at normal conditions are presented. The data, collected at CERN (PS T9 beam), indicate that the cluster-counting technique allows a substantial improvement with respect to the more traditional measurements. π/K separation of ≅ 3.6σ at 4 GeV was obtained over the entire volume of the chamber: 144 (3 x 3) cm² cells with an average tracks path length of 120 cm. (author)

[en] The LHCb measurement of the J/ψ production cross-section is presented. The double differential cross-section is measured as a function of the J/ψ transverse momentum p_T and of the J/ψ rapidity y in the fiducial region 0 GeV ≤ p_T ≤ 14 GeV/c and 2 ≤ y ≤ 4:5. The analysis is based on a sample of 5.2 pb^-1 collected in September 2010 at the p-p Large Hadron Collider at CERN, at a centre of mass energy of 7 TeV. The contributions from prompt J/ψ and J/ψ from B-meson are separated using the J/ψ pseudo-proper time. (author)

[en] 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 MΩ to more than 250 MΩ. A corresponding degradation of the RPC rate capabilities, from more than 3 kHz/cm 2 to less than 0.15 kHz/cm² is also found

[en] This paper describes the performances of a large volume drift chamber with complete digitization of the output pulses. The electronics used in this test include wide-band (700 MHz) amplifiers and fast (1 Gsample/s) digitizers. The gas mixture selected for drift chamber operation (80% He-20% CH₄) and the signal processing mentioned above allow the measurement of the primary ionization clusters. The improvement in the (wire) impact parameter evaluation of the primary particle is sizeable

[en] We present recent results of an extensive aging test, performed at the CERN Gamma Irradiation Facility, on two bakelite Resistive Plate Chambers (RPC) detectors. With a method based on a model describing the behavior of an RPC exposed to a large particle flux, we have periodically measured the electrode resistivity ρ of the two detectors over 3 years. We observed a large increase of ρ with time, from initial values of about 10¹⁰ Ω cm to more than 200x10¹⁰ Ω cm. A corresponding degradation of the RPC rate capability, from about 3 kHz/cm² to less than 200 Hz/cm², was observed. The reversibility of the process, using a humid gas mixture, has also been studied

[en] We present a simple model to describe the behavior of Resistive Plate Chambers (RPC) exposed to a high particle flux. We show that the RPC current, I, saturates at large flux values and we explain why the dependence of I on the applied voltage V₀ is essentially linear. We show that in the saturated regime the current is controlled by the value of the bulk electrode resistivity, ρ, which is directly related to the performance of the detector at high particle rates. Measuring the I-V₀ curve under these conditions offers a simple and direct method to obtain ρ and to monitor its possible variations

[en] 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/cm², 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/cm² 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

[en] The preliminary 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 density of 0.42 C/cm², corresponding to about 4 years of LHCb running at the highest background rate. We observe a rise in the dark current and noise measured with source off. The current drawn with source on steadily decreased, possibly indicating an increase of resistivity of the chamber plates. The performance of the chamber, studied with a muon beam under several photon flux values, is found to still fulfill the LHCb operation requirements