S. Bagnasco

Resistive plate chamber performance in the BaBar IFR system

The BaBar Collaboration has operated a system covering over 2000 m/sup 2/ with resistive plate chambers for nearly three years. The chambers are constructed of bakelite sheets separated by 2 mm. The inner surfaces are coated with linseed oil. This system provides muon and neutral hadron detection for BaBar. Installation and commissioning were completed in 1998, and operation began mid-1999. While initial performance of the system reached design, over time, a significant fraction of the resistive plate chambers demonstrated significant degradation, marked by increased currents and reduced efficiency. A coordinated investigative effort has identified many of the elements responsible for the degradation.

The BaBar instrumented flux return performance: lessons learned

Abstract The BaBar Collaboration has operated an instrumented flux return (IFR) system covering over 2000 m 2 with resistive plate chambers (RPCs) for nearly 3 years. The chambers are constructed of bakelite sheets separated by 2 mm . The inner surfaces are coated with linseed oil. This system provides muon and neutral hadron detection for BaBar. Installation and commissioning were completed in 1998, and operation began mid-year 1999. While initial performance of the system reached design, over time, a significant fraction of the RPCs demonstrated significant degradation, marked by increased currents and reduced efficiency. A coordinated effort of investigations have identified many of the elements responsible for the degradation. This article presents our current understanding of the aging process of the BaBar RPCs along with the action plan to combat performance degradation of the IFR system.

Inclusive photon production at forward rapidities in proton–proton collisions at √s = 0.9, 2.76 and 7 TeV - eScholarship

The multiplicity and pseudorapidity distributions of inclusive photons have been measured at forward rapidities (2.3 < η < 3.9) in proton–proton collisions at three center-of-mass energies, √ s = 0.9, 2.76 and 7 TeV using the ALICE detector. It is observed that the increase in the average photon multiplicity as a function of beam energy is compatible with both a logarithmic and a power-law dependence. The relative increase in average photon multiplicity produced in inelastic pp collisions at 2.76 and 7 TeV center-of-mass energies with respect to 0.9 TeV are 37.2 ± 0.3 % (stat) ± 8.8 % (sys) and 61.2 ± 0.3 % (stat) ± 7.6 % (sys), respectively. The photon multiplicity distributions for all center-of-mass energies are well described by negative binomial distributions. The multiplicity distributions are also presented in terms of KNO variables. The results are compared to model predictions, which are found in general to underestimate the data at large photon multiplicities, in particular at the highest center-of-mass energy. Limiting fragmentation behavior of photons has been explored with the data, but is not observed in the measured pseudorapidity range.

Production of Σ (1385)±and Ξ (1530)0in p–Pb collisions at √sNN=5.02 TeV

The transverse momentum distributions of the strange and double-strange hyperon resonances ([Formula: see text], [Formula: see text]) produced in p-Pb collisions at [Formula: see text] TeV were measured in the rapidity range [Formula: see text] for event classes corresponding to different charged-particle multiplicity densities, [Formula: see text]d[Formula: see text]/d[Formula: see text]. The mean transverse momentum values are presented as a function of [Formula: see text]d[Formula: see text]/d[Formula: see text], as well as a function of the particle masses and compared with previous results on hyperon production. The integrated yield ratios of excited to ground-state hyperons are constant as a function of [Formula: see text]d[Formula: see text]/d[Formula: see text]. The equivalent ratios to pions exhibit an increase with [Formula: see text]d[Formula: see text]/d[Formula: see text], depending on their strangeness content.The transverse momentum distributions of the strange and double-strange hyperon resonances (

Event-by-event mean pT fluctuations in pp and Pb–Pb collisions at the LHC - eScholarship

\Sigma (1385)^{\pm }

Mechanisms affecting performance of the BaBar resistive plate chambers and searches for remediation

Σ(1385)±,

First measurement of Ξc0production in pp collisions at s=7 TeV

\Xi (1530)^{0}