PACIFIC: the readout ASIC for the SciFi Tracker of the upgraded LHCb detector

The LHCb detector will be upgraded during the Long Shutdown 2 (LS2) of the LHC in order to cope with higher instantaneous luminosities and will switch to a 40 MHz readout rate using a trigger-less software based system. All front-end electronics will be replaced and several sub-detectors must be redesigned to cope with the higher detector occupancy and radiation damage. The current tracking detectors downstream of the LHCb dipole magnet will be replaced by the Scintillating Fibre (SciFi) Tracker. The SciFi Tracker will use scintillating fibres read out by Silicon Photomultipliers (SiPMs). State-of-the-art multi-channel SiPM arrays are being developed and a custom ASIC, called the low-Power ASIC for the sCIntillating FIbres traCker (PACIFIC), will be used to digitise the signals from the SiPMs. This article presents an overview of the R&D for the PACIFIC. It is a 64-channel ASIC implemented in 130 nm CMOS technology, aiming at a radiation tolerant design with a power consumption below 10 mW per channel. It interfaces directly with the SiPM anode through a current mode input, and provides a configurable non-linear 2-bit per channel digital output. The SiPM signal is acquired by a current conveyor and processed with a fast shaper and a gated integrator. The digitization is performed using a three threshold non-linear flash ADC operating at 40 MHz. Simulation and test results show the PACIFIC chip prototypes functioning well

FastIC: a fast integrated circuit for the readout of high performance detectors

This work presents the 8-channel FastIC ASIC developed in CMOS 65 nm technology suitable for the readout of positive and negative polarity sensors in high energy physics experiments, Cherenkov detectors and time-of-flight systems. The front-end can be configured to perform analog summation of up to 4 single-ended channels before discrimination in view of improving time resolution when segmenting a SiPM. The outputs encode the time-of-arrival information and linear energy measurement which captures the peak amplitude of the input signal in the 5 µA–25 mA input peak current range. Power consumption of the ASIC is 12 mW/ch with default settings. Measurements of single photon time resolution with a red-light laser source and a HPK SiPM S13360-3050CS are ≈140 ps FWHM

An improved neural network technique for data dimensionality reduction in satellite imagery

This paper presents an application of back-propagation neural network based mapping scheme of multispectrale data images. The approach exploits the ability of neural networks for non-linear projection of multidimensional data, and their advantages over traditional methods. An updating rule for this network, based on the Conjugate Gradient Algorithm is used. The main advantage of this algorithm is the speedup of the convergence rate. Performance evaluation using a Landsat image of Kénitra region (Morocco) is carried out. Classification results of the proposed algorithm outperform those obtained using conventional methods.Ce papier présente une nouvelle technique de réduction du nombre de canaux spectraux pour aider à la classification des images multispectrales en mode d'occupation du sol. Cette technique, basée sur des réseaux de neurones multicouches, propose une règle d'apprentissage de ces réseaux qui adapte le gradient conjugué à la méthode de rétropropagation; permettant ainsi une convergence rapide au réseau. Les résultats de classification sont évalués sur une fenêtre d'image Landsat-TM de 512*512 pixels, relative à la région de Kénitra (Maroc), et comparés à ceux obtenus par les méthodes classiques

Value of staging squamous cell carcinoma of the anal margin and canal using the sentinel lymph node procedure: an update of the series and a review of the literature.

BACKGROUND: Inguinal metastases in patients affected by anal cancer are an independent prognostic factor for local failure and overall mortality. Since 2001, sentinel lymph node biopsy was applied in these patients. This original study reports an update of personal and previous published series, which were compared with Literature to value the incidence of inguinal metastases T-stage related and the overall incidence of false negative inguinal metastases at sentinel node. METHODS: In all, 63 patients diagnosed with anal cancer submitted to inguinal sentinel node. Furthermore a research in the Pub Med database was performed to find papers regarding this technique. RESULTS: In our series, detection rate was 98.4%. Inguinal metastases were evidentiated in 13 patients (20.6%). Our median follow-up was 35 months. In our series, no false negative nodes were observed. CONCLUSION: Sentinel node technique in the detection of inguinal metastases in patients affected by anal cancer should be considered as a standard of care. It is indicated for all T stages in order to select patients to be submitted to inguinal radiotherapy, avoiding related morbidity in negative ones. An overall 3.7% rate of false negative must be considered acceptable

Quantum numbers of the X (3872 ) state and orbital angular momentum in its ρ0J /ψ decay

Angular correlations in B+ → X(3872)K+ decays, with X(3872) → ρ 0J/ψ, ρ 0 → π +π − and J/ψ → µ +µ −, are used to measure orbital angular momentum contributions and to determine the J P C value of the X(3872) meson. The data correspond to an integrated luminosity of 3.0 fb−1 of proton-proton collisions collected with the LHCb detector. This determination, for the first time performed without assuming a value for the orbital angular momentum, confirms the quantum numbers to be J P C = 1++. The X(3872) is found to decay predominantly through S wave and an upper limit of 4% at 95% C.L. is set on the D-wave contribution

Search for beautiful tetraquarks in the ϒ(1S)μ + μ − invariant-mass spectrum

Abstract: The Υ(1S)µ +µ − invariant-mass distribution is investigated for a possible exotic meson state composed of two b quarks and two b quarks, Xbbbb . The analysis is based on a data sample of pp collisions recorded with the LHCb detector at centre-of-mass energies √ s = 7, 8 and 13 TeV, corresponding to an integrated luminosity of 6.3 fb−1 . No significant excess is found, and upper limits are set on the product of the production cross-section and the branching fraction as functions of the mass of the Xbbbb state. The limits are set in the fiducial volume where all muons have pseudorapidity in the range [2.0, 5.0], and the Xbbbb state has rapidity in the range [2.0, 4.5] and transverse momentum less than 15 GeV/c. Keywords: B physics, Exotics, Hadron-Hadron scattering (experiments), Heavy quark productio

Central exclusive production of J/ψ and ψ(2S) mesons in pp collisions at √s=13 TeV

Measurements are reported of the central exclusive production of J/ψ and ψ(2S) mesons in pp collisions at a centre-of-mass energy of 13 TeV. Backgrounds are significantly reduced compared to previous measurements made at lower energies through the use of new forward shower counters. The products of the cross-sections and the branching fractions for the decays to dimuons, where both muons are within the pseudorapidity range 2.0 < η < 4.5, are measured to be σJ/ψ→µ+µ− = 435 ± 18 ± 11 ± 17 pb σψ(2S)→µ+µ− = 11.1 ± 1.1 ± 0.3 ± 0.4 pb. The first uncertainties are statistical, the second are systematic, and the third are due to the luminosity determination. The cross-sections are also measured differentially for meson rapidities between 2.0 and 4.5. Good agreement is observed with theoretical predictions. Photoproduction cross-sections are derived and compared to previous experiments, and a deviation from a pure power-law extrapolation of lower energy data is observed

Measurement of the time-integrated CP asymmetry in D 0 → KS 0 KS 0 decays

Abstract: A measurement of the time-integrated CP asymmetry in D0 → K0 SK0 S decays is reported. The data correspond to an integrated luminosity of about 2 fb−1 collected in 2015-2016 by the LHCb collaboration in pp collisions at a centre-of-mass energy of 13 TeV. The D0 candidate is required to originate from a D∗+ → D0π + decay, allowing the determination of the flavour of the D0 meson using the pion charge. The D0 → K+K− decay, which has a well measured CP asymmetry, is used as a calibration channel. The CP asymmetry for D0 → K0 SK0 S is measured to be A CP (D0 → K0 SK0 S ) = (4.3 ± 3.4 ± 1.0)%, where the first uncertainty is statistical and the second is systematic. This result is combined with the previous LHCb measurement at lower centre-of-mass energies to obtain A CP (D0 → K0 SK0 S ) = (2.3 ± 2.8 ± 0.9)%. Keywords: Charm physics, CP violation, Flavor physics, Hadron-Hadron scattering (experiments

Search for lepton-flavour-violating decays of Higgs-like bosons

A search is presented for a Higgs-like boson with mass in the range 45 to 195 GeV/c2 decaying into a muon and a tau lepton. The dataset consists of proton-proton interactions at a centre-of-mass energy of 8 TeV, collected by the LHCb experiment, corresponding to an integrated luminosity of 2 fb−1 . The tau leptons are reconstructed in both leptonic and hadronic decay channels. An upper limit on the production cross-section multiplied by the branching fraction at 95% confidence level is set and ranges from 22 pb for a boson mass of 45 GeV/c2 to 4 pb for a mass of 195 GeV/c2

Study of ϒ production in pPb collisions at √sNN=8.16 TeV

Abstract: The production of Υ(nS) mesons (n = 1, 2, 3) in pPb and Pbp collisions at a centre-of-mass energy per nucleon pair √ sNN = 8.16 TeV is measured by the LHCb experiment, using a data sample corresponding to an integrated luminosity of 31.8 nb−1 . The Υ(nS) mesons are reconstructed through their decays into two opposite-sign muons. The measurements comprise the differential production cross-sections of the Υ(1S) and Υ(2S) states, their forward-to-backward ratios and nuclear modification factors. The measurements are performed as a function of the transverse momentum pT and rapidity in the nucleon-nucleon centre-of-mass frame y ∗ of the Υ(nS) states, in the kinematic range pT < 25 GeV/c and 1.5 < y∗ < 4.0 (−5.0 < y∗ < −2.5) for pPb (Pbp) collisions. In addition, production cross-sections for Υ(3S) are measured integrated over phase space and the production ratios between all three Υ(nS) states are determined. Suppression for bottomonium in proton-lead collisions is observed, which is particularly visible in the ratios. The results are compared to theoretical models