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Campagnari, C.

Publications and source records attributed to Campagnari, C..

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Test beam characterization of sensor prototypes for the CMS Barrel MIP Timing Detector

The MIP Timing Detector will provide additional timing capabilities for detection of minimum ionizing particles (MIPs) at CMS during the High Luminosity LHC era, improving event reconstruction and pileup rejection. The central portion of the detector, the Barrel Timing Layer (BTL), will be instrumented with LYSO:Ce crystals and Silicon Photomultipliers (SiPMs) providing a time resolution of about 30 ps at the beginning of operation, and degrading to 50-60 ps at the end of the detector lifetime as a result of radiation damage. In this work, we present the results obtained using a 120 GeV proton beam at the Fermilab Test Beam Facility to measure the time resolution of unirradiated sensors. A proof-of-concept of the sensor layout proposed for the barrel region of the MTD, consisting of elongated crystal bars with dimensions of about 3×3×57 mm3 and with double-ended SiPM readout, is demonstrated. This design provides a robust time measurement independent of the impact point of the MIP along the crystal bar. We tested LYSO:Ce bars of different thickness (2, 3, 4 mm) with a geometry close to the reference design and coupled to SiPMs manufactured by Hamamatsu and Fondazione Bruno Kessler. The various aspects influencing the timing performance such as the crystal thickness, properties of the SiPMs (e.g. photon detection efficiency), and impact angle of the MIP are studied. A time resolution of about 28 ps is measured for MIPs crossing a 3 mm thick crystal bar, corresponding to a most probable value (MPV) of energy deposition of 2.6 MeV, and of 22 ps for the 4.2 MeV MPV energy deposition expected in the BTL, matching the detector performance target for unirradiated devices.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

Search for Long-Lived Particles in e + e - Collisions

We present a search for a neutral, long-lived particle L that is produced in e + e - collisions and decays at a significant distance from the e + e - interaction point into various flavor combinations of two oppositely charged tracks. The analysis uses an e + e - data sample with a luminosity of 489.1 fb -1 collected by the BABAR detector at the γ (4S), γ (3S), and γ (2S) resonances and just below the γ (4S). Fitting the two-track mass distribution in search of a signal peak, we do not observe a significant signal, and set 90% confidence level upper limits on the product of the L production cross section, branching fraction, and reconstruction efficiency for six possible two-body L decay modes as a function of the L mass. The efficiency is given for each final state as a function of the mass, lifetime, and transverse momentum of the candidate, allowing application of the upper limits to any production model. In addition, upper limits are provided on the branching fraction B(B→X s L), where X s is a strange hadronic system.

Lees, J. P.↗
DOE OSTI2014

Search for a Dark Photon in e + e - Collisions at BaBar

Dark sectors charged under a new Abelian interaction have recently received much attention in the context of dark matter models. These models introduce a light new mediator, the so-called dark photon (A'), connecting the dark sector to the standard model. We present a search for a dark photon in the reaction e + e - →γA', A'→e + e - , μ + μ - using 514 fb -1 of data collected with the BABAR detector. We observe no statistically significant deviations from the standard model predictions, and we set 90% confidence level upper limits on the mixing strength between the photon and dark photon at the level of10 -4 -10 -3 for dark photon masses in the range 0.02–10.2 GeV We further constrain the range of the parameter space favored by interpretations of the discrepancy between the calculated and measured anomalous magnetic moment of the muon.

Lees, J. P.↗
DOE OSTI2013

Search for C P Violation in B 0 - B ¯ 0 Mixing Using Partial Reconstruction of B 0 → D * - X ℓ + ν ℓ and a Kaon Tag

We present results of a search for CP violation in B 0 -B¯ 0 mixing with the BABAR detector. We select a sample of B 0 →D* - Xℓ+ν decays with a partial reconstruction method and use kaon tagging to assess the flavor of the other B meson in the event. We determine the CP violating asymmetry ACP≡[N(B 0 B 0 )-N(B¯ 0 B¯ 0 )]/[N(B 0 B 0 )+N(B¯ 0 B¯ 0 )]=(0.06±0.17+0.38-0.32)%, corresponding to ΔCP=1-|q/p|=(0.29±0.84 +1.88 -1.61 )×10 -3 .

43 PARTICLE ACCELERATORS↗
DOE OSTI2013

Search for a light Higgs boson decaying to two gluons or ss̄ in the radiative decays of Υ(1S)

We search for the decay Υ(1S)→γA⁰, A⁰→gg or ss̄, where A⁰ is the pseudoscalar light Higgs boson predicted by the next-to-minimal supersymmetric Standard Model. We use a sample of (17.6±0.3)×10⁶ Υ(1S) mesons produced in the BABAR experiment via e⁺e⁻→Υ(2S)→π⁺π⁻Υ(1S). We see no significant signal and set 90%-confidence-level upper limits on the product branching fraction B(Υ(1S)→γA⁰)·B(A⁰→gg or ss̄) ranging from 10⁻⁶ to 10⁻² for A⁰ masses in the range 0.5–9.0 GeV/c².

Lees, J. P.↗