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Measurement of φs in Run2 at LHCb
No full textTwo recent measurements of CP-violating parameters are presented, obtained using proton-proton collision data collected by the LHCb detector in 2015 and 2016 at a centre-of-mass energy of 13 TeV. In particular, the measurement of
the CP-violating phase φs using a time-dependent analysis of the Bs → J/ψK+K− and Bs → J/ψπ+π− channels is described
Fermilab Muon g − 2 experiment: Current status
No full textThe Muon g − 2 experiment at Fermilab (E989) is currently measuring the muon magnetic anomaly with a goal precision of 140 part per billion, which will be a fourfold precision improvement over the current best measurement
by the previous Muon g − 2 experiment at the Brookhaven Laboratory (BNL). The BNL-measured value of the muon magnetic anomaly and the corresponding Standard Model (SM) best estimate differ by more than three standard deviation which inspired the current measurement as well as a theoretical drive for a significantly more precise calculation of the muon magnetic anomaly to rule out (or establish) statistical fluctuation as the origin of such a huge discrepancy. Stable central values along with 4-fold precision improvements in both theoretical (SM) and experimental fronts, would imply a ∼ 7σ discrepancy and that will be a clear hint of the physics beyond the Standard Model. Such an unprecedented precision demands
state-of-the-art technological improvements in all involved components to keep the systematic uncertainty below 70 ppb. This paper reports the current status of the
E989 experiment after two years of data acquisition
Test procedures and characterization of silicon photomultipliers for photometric detection in astrophysics
No full textSilicon photomultipliers (SiPM) are a typology of solid-state sensors that in recent years are replacing the established photomultiplier tube technology in a variety of uses. This kind of sensors find high demand in experiments carried out at very low light intensity (in the order of single photon detection) and also where high temporal precision (of the order of ns) and a reduced geometric encumbrance is required. The Bruno Kessler Foundation (FBK) has developed the near ultra violet high density low cross-talk (NUV-HD Low-CT) sensor optimized for the detection of photons in the ultraviolet spectrum jointly with a minimization of the optical cross-talk between adjacent microcells. These sensors are particularly suitable for equipping the imaging air cherenkov telescopes as intended for the CTA observatory.
Optical modules consisting of 16 SiPMs (each one of 6 × 6 mm2) were assembled in INFN laboratories to be integrated into the focal plane of the medium-sized telescope prototype with a Schwarzschild-Couder double-mirror optic (SCT). This report will describe the test procedures to verify the performance of these 6×6 mm2 sensors. Furthermore the assembly procedures developed to integrate the sensors on the detection modules and equip the focal plane chamber of the SCT prototype telescope (currently operational and under testing at the Fred Lawrence Whipple
Observatory, Arizona) will also be presented
Directional detection of dark matter with a nuclear emulsion based detector
No full textCosmological observations indicate that the major part of our Universe is composed of dark matter (DM). The DM in the form of Weakly Interacting Massive Particles (WIMP) can be detected directly through its scattering inside the
detector. Most direct detection experiments measure only the energy of recoiled nuclei. The NEWSdm experiment is the first directional DM search experiment with a solid-state detector: the use of nano-grained nuclear emulsions both as a target material and as a nanometric-resolution tracking device will enable overcoming the so-called neutrino floor and will provide an unambiguous proof of the galactic origin of DM
Lepton Flavour Universality tests in the decay channel B0 → D∗− τ +ντ with τ + → π+π−π+ν¯τ at LHCb
No full textThis document reports the first measurement of B0 → D∗− τ +ντ
branching fraction performed by the LHCb Collaboration considering semileptonic b-hadron decays with the τ lepton reconstructed with three charged pions in the final state. The impact of such measurement on the current tests of lepton flavour universality is discussed
Search for chargino neutralino production in final states with a W boson and Higgs boson
No full textSupersymmetry (SUSY) is an extension of the Standard Model (SM), and its searches are a central part of ATLAS physics program. In this proceeding, the most recent result in searches of chargino ( ˜χ± 1 ) and neutralino ( ˜χ0 2) production where ˜χ± 1 decays in a W boson and the lightest and stable SUSY particle ( ˜χ0 1), while ˜χ0 2 decays in the lightest SUSY particle and a SM Higgs boson is reported. The search was based on the analysis of 36.1 fb−1 pp collision data recorded by the ATLAS experiment at √s = 13 TeV. Fully hadronic, semileptonic, diphoton, and
multilepton (electrons, muons) final states with missing transverse momentum are considered in this search. Higgs bosons in the final state are identified by either two jets originating from bottom quarks (h → bb−), two photons (h → γγ), or leptons from the decay modes h → WW, h → ZZ or h → τ τ . As no SUSY signal was observed, the confidence level limits on charginos and neutralinos masses in the context of simplified SUSY models are reported
Transition-metal dichalcogenides with type-II Dirac fermions: Surface properties and application capabilities
No full textAmong the various layered materials “beyond graphene”, the class of transition-metal dichalcogenides MTe2 (M= Ni, Pd, Pt) is particularly interesting, due to the existence of bulk type-II Dirac fermions, arising from a tilted Dirac
cone. The Dirac cone in these materials is located in the bulk, with inherently superior robustness to surface modifications compared to other Dirac materials, among which graphene, topological insulator and silicene. In addition, MTe2 also displays application capabilities in optoelectronics and catalysis. Here, with surfacescience experiments and theory, we assess the surface properties of MTe2, including i) ambient stability, ii) chemical reactivity and iii) aging mechanisms. Remarkably, MTe2 shows outstanding tolerance to CO and stability in water environment. We also demonstrate that passivation in ambient atmosphere is achieved in less than 30 minutes with the TeO2 skin having a sub-nanometric thickness even after one year in the air. The existence of Te vacancies leads to the enhancement of the surface chemical reactivity. These results pave the way toward the exploitation of this class of Dirac materials in optoelectronics and catalysis
FPGA implementation of a highly efficient pulse discrimination trigger algorithm for the JUNO large PMTs readout electronics
No full textThe Jiangmen Underground Neutrino Observatory (JUNO) is a
neutrino physics experiment located in China. A 20 kton multipurpose underground Liquid Scintillator (LS) will allow the determination of the neutrino mass hierarchy by measuring the nuclear antineutrino energy spectrum. An excellent energy resolution and a large detector fiducial volume are key ingredients for addressing many important topics in neutrino and astroparticle physics. The LS detector is instrumented by 18000 20 inches PhotoMultiplier Tubes (PMT) which corresponds to about 75% of coverage. The Front-End readout electronics focuses on the Global Control Unit (GCU) board which, thanks to the on-board Field Programmable Gate Array (FPGA), is able to do an online processing of the PMTs waveform, providing
first-level trigger requests as well as timing synchronization and data forwarding to the Data Acquisition (DAQ) system. The JUNO experiment requires an evaluation of single photoelectron signals originated by the PMTs and, in this conditions, the signal amplitude is comparable to the electronics background noise. Therefore,
the paper aims to describe a new kind of trigger algorithm, featuring a high discrimination power. After having defined its architecture, the test section compares
the pulse detection efficiency in low Signal-to-Noise Ratio (SNR) scenarios, with a simple leading-edge trigger
Studying the rheology of geophysical flows with physical-mathematical models: An application of the GPUSPH particle engine
No full textWe present an application of GPUSPH, a particle engine based on the Smoothed Particle Hydrodynamics numerical method with implementation on Graphic Processing Units (GPUs) for high performance, to the study of the rheology of geophysical flows