1,579 research outputs found
The ALICE Level 0 Pixel Trigger Driver Layer
The ALICE Silicon Pixel Detector (SPD) comprises the two innermost layers of the ALICE inner tracker system. The SPD contains 120 detector modules each including 10 readout chips. Each of these pixel chips generates a digital Fast-OR output signal indicating the presence of at least one pixel hit in its pixel
matrix.
The Pixel Trigger (PIT) System has been implemented to process the 1200 Fast-Or signals from the SPD and provides an input signal to the ALICE Central Trigger Processor (CTP) for the fastest (Level 0) trigger decision within a latency of 800 ns.
The PIT processor interfaces with several ALICE systems: it receives input data from the SPD, it accepts configuration commands from the CTP and sends status information to the Alice Experimental Control System (ECS). The PIT control system required an accurate design of hardware and software solutions to implement coordinated operation of the PIT and the ALICE systems to which it interfaces to.
We present here the design, the implementation and the first operational experience of the PIT Control and Calibration system. The hardware configuration and control are implemented via the ALICE Detector Data Link, on top of which a custom control system has been implemented.
A driver layer has been realized under stringent requirements of robustness and reusability. It qualifies as a general purpose hardware driver for electronic systems equipped with the ALICE DDL front end board (SIU).
Various testing and calibration procedures need to be performed on the SPD and the PIT systems in order to provide an optimized trigger signal to the CTP.
These include methods to compensate all signals propagation delays and automatic SPD DAC scans to tune the detector response. The PIT control system has been tailored to implement automatically most of the former procedures, requiring coordinated and extensive information exchange between the interfacing systems.CER
Digital Pixel Test Structures implemented in a 65 nm CMOS process
The ALICE ITS3 (Inner Tracking System 3) upgrade project and the CERN EP R&D
on monolithic pixel sensors are investigating the feasibility of the Tower
Partners Semiconductor Co. 65 nm process for use in the next generation of
vertex detectors. The ITS3 aims to employ wafer-scale Monolithic Active Pixel
Sensors thinned down to 20 to 40 um and bent to form truly cylindrical half
barrels. Among the first critical steps towards the realisation of this
detector is to validate the sensor technology through extensive
characterisation both in the laboratory and with in-beam measurements. The
Digital Pixel Test Structure (DPTS) is one of the prototypes produced in the
first sensor submission in this technology and has undergone a systematic
measurement campaign whose details are presented in this article.
The results confirm the goals of detection efficiency and non-ionising and
ionising radiation hardness up to the expected levels for ALICE ITS3 and also
demonstrate operation at +20 C and a detection efficiency of 99% for a DPTS
irradiated with a dose of 1 MeV ncm.
Furthermore, spatial, timing and energy resolutions were measured at various
settings and irradiation levels.Comment: Updated threshold calibration method. Implemented colorblind friendly
color palette in all figures. Updated reference
Event-by-event mean pT fluctuations in pp and Pb–Pb collisions at the LHC
Event-by-event fluctuations of the mean transverse momentum of charged particles produced in pp collisions at TeX TeX 0.9, 2.76 and 7 TeV, and Pb–Pb collisions at TeX TeX 2.76 TeV are studied as a function of the charged-particle multiplicity using the ALICE detector at the LHC. Dynamical fluctuations indicative of correlated particle emission are observed in all systems. The results in pp collisions show little dependence on collision energy. The Monte Carlo event generators PYTHIA and PHOJET are in qualitative agreement with the data. Peripheral Pb–Pb data exhibit a similar multiplicity dependence as that observed in pp. In central Pb–Pb, the results deviate from this trend, featuring a significant reduction of the fluctuation strength. The results in Pb–Pb are in qualitative agreement with previous measurements in Au–Au at lower collision energies and with expectations from models that incorporate collective phenomena
Production of charged pions, kaons and protons at large transverse momenta in pp and Pb-Pb collisions at = 2.76 TeV
Transverse momentum spectra of and up to = 20 GeV/c at mid-rapidity, |y| 0.8, in pp and Pb-Pb collisions at = 2.76 TeV have been measured using the ALICE detector at the LHC. At intermediate (2-8 GeV/c) an enhancement of the proton-to-proton ratio, (p + \bar{p})/(\pi^+ + \pi^-\(), with respect to pp collisions is observed and the ratio reaches 0.80 in central Pb-Pb collisions. The measurement of the nuclear modification factors for \(\pi^{\pm}, K^{\pm} and indicates that within the systematic and statistical uncertainties they are the same at high (> 10 GeV/c), suggesting that the chemical composition of leading particles from jets in the medium is similar to that of vacuum jets.publishedVersio
The Behavior, onḂ0,11, of an Oscillatory Integral with Polynomial Phase Function
AbstractWe study the convolution oscillatory singular integral operatorTf=p.v.Ω∗f, with Ω(x)=eiq(x)K(x), whereqis a real-valued polynomial of a real variable, of degreed≥2, andKis a Calderón–Zygmund-type kernel. We prove that this operator extends to an operator that maps the Besov spaceḂ0,11into the Hardy-type spaceH10
Multiplicity dependence of the average transverse momentum in pp, p-Pb, and Pb-Pb collisions at the LHC
The average transverse momentum versus the charged-particle multiplicity was measured in p-Pb collisions at a collision energy per nucleon-nucleon pair = 5.02 TeV and in pp collisions at collision energies of = 0.9, 2.76, and 7 Tev in the kinematic range 0.15 with is observed, which is much stronger than that measured in Pb-Pb collisions. For pp collisions, this could be attributed, within a model of hadronizing strings, to multiple-parton interactions and to a final-state color reconnection mechanism. The data in p-Pb and Pb-Pb collisions cannot be described by an incoherent superposition of nucleon-nucleon collisions and pose a challenge to most of the event generators.publishedVersio
Measurement of the Cross Section for Electromagnetic Dissociation with Neutron Emission in Pb-Pb Collisions at √sNN = 2.76 TeV
The first measurement of neutron emission in electromagnetic dissociation of 208Pb nuclei at the LHC is presented. The measurement is performed using the neutron Zero Degree Calorimeters of the ALICE experiment, which detect neutral particles close to beam rapidity. The measured cross sections of single and mutual electromagnetic dissociation of Pb nuclei at √sNN = 2.76 TeV with neutron emission are σ_single EMD = 187.2±0.2 (stat.) +13.8−12.0 (syst.) b and σ_mutual EMD = 6.2 ± 0.1 (stat.) ±0.4 (syst.) b respectively. The experimental results are compared to the predictions from a relativistic electromagnetic dissociation model.publishedVersio
Measurement of charm and beauty production at central rapidity versus charged-particle multiplicity in proton-proton collisions at = 7 TeV
Prompt D meson and non-prompt J/ yields are studied as a function of the multiplicity of charged particles produced in inelastic proton-proton collisions at a centre-of-mass energy of TeV. The results are reported as a ratio between yields in a given multiplicity interval normalised to the multiplicity-integrated ones (relative yields). They are shown as a function of the multiplicity of charged particles normalised to the average value for inelastic collisions (relative charged-particle multiplicity). D\)^0\), D\)^+\) and D\)^{*+}\) mesons are measured in five intervals from 1 to 20 GeV/ and for GeV/ and , The fraction of non-prompt J/ in the inclusive J/ yields shows no dependence on the charged-particle multiplicity at central rapidity. Charm and beauty hadron relative yields exhibit a similar increase with increasing charged-particle multiplicity. The measurements are compared to PYTHIA 8, EPOS 3 and percolation calculations.publishedVersio
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