5,955 research outputs found
The ALICE TPC : a large 3-dimensional tracking device with fast readout for ultra-high multiplicity events
No full textThe design, construction, and commissioning of the ALICE Time-Projection Chamber (TPC) is described. It is the main device for pattern recognition, tracking, and identification of charged particles in the ALICE experiment at the CERN LHC. The TPC is cylindrical in shape with a volume close to 90 m3 and is operated in a 0.5 T solenoidal magnetic field parallel to its axis.
In this paper we describe in detail the design considerations for this detector for operation in the extreme multiplicity environment of central Pb–Pb collisions at LHC energy. The implementation of the resulting requirements into hardware (field cage, read-out chambers, electronics), infrastructure (gas and cooling system, laser-calibration system), and software led to many technical innovations which are described along with a presentation of all the major components of the detector, as currently realized. We also report on the performance achieved after completion of the first round of stand-alone calibration runs and demonstrate results close to those specified in the TPC Technical Design Report
Performance of the ALICE SPD cooling system
No full textThe new generation of silicon detectors for particle physics requires very reduced mass and high resistance to radiations with very limited access to the detector for maintenance. The Silicon Pixel Detector (SPD) is one of the 18 detectors of the ALICE (A Large Ion Collider Experiment) experiment at the Large Hadron Collider (LHC) at CERN. It constitutes the two innermost layers of the Inner Tracking System (ITS) and it is the closest detector to the interaction point.
An evaporative cooling system, based on C4F10 evaporation at 1.9 bar, was chosen to extract the 1.35 kW power dissipated by the on-detector electronics. The whole system was extensively tested and commissioned before its installation inside the ALICE experimental area. Since then we had to deal with a decrease of the flow in some lines of the system that imposed severe restrictions on the detector operation. Recently, a test bench has been built in order to carry out a series of tests to reproduce the misbehaviour of the system and investigate proper actions to cure the problem.
The performance of the systems and the most interesting results of the above mentioned tests will be presented
Validation of the 65 nm TPSCo CMOS imaging technology for the ALICE ITS3
No full textDuring the next Long Shutdown (LS3) of the LHC, planned for 2026, the innermost three
layers of the ALICE Inner Tracking System will be replaced by a new vertex detector composed of curved ultra-thin monolithic silicon sensors. The R&D initiative on monolithic sensors of the CERN Experimental Physics Department, in cooperation with the ALICE ITS3 upgrade project, prepared the first submission of chip designs in the TPSCo 65 nm technology, called MLR1 (Multi Layer Reticle). It contains four different test structures with different process splits and pixel designs. These proceedings illustrate the first validation of the technology in terms of pixel performance and radiation hardness
The ALICE Transition Radiation Detector : Construction, operation, and performance
No full textThe Transition Radiation Detector (TRD) was designed and built to enhance the capabilities of the ALICE detector at the Large Hadron Collider (LHC). While aimed at providing electron identification and triggering, the TRD also contributes significantly to the track reconstruction and calibration in the central barrel of ALICE. In this paper the design, construction, operation, and performance of this detector are discussed. A pion rejection factor of up to 410 is achieved at a momentum of 1 GeV/c in p-Pb collisions and the resolution at high transverse momentum improves by about 40% when including the TRD information in track reconstruction. The triggering capability is demonstrated both for jet, light nuclei, and electron selection. (c) 2017 CERN for the benefit of the Authors. Published by Elsevier B.V.Peer reviewe
The Journey from Australia to Italy of Alice Pung’s Bestselling Novel
No full textAlice Pung's Unpolished Gem was translated into Italian in 2010. Giving some examples of the challenge this work of translation presented, Adele D'Arcangelo will try to put Pung's novel in the picture of a wider production of multicultural literature available in Italy. Positive aspects related to the reception of Gemma Impura in Italy will be pointed out as well as the vital and fundamental collaboration between author and translator. The innate potentialities of Unpolished Gem to transform a personal experience in a universal one were doubled by the translation of the book in another language, allowing a wider and more eclectic readership to become familiar with Alice's story, and making its Australian setting overcome the boundaries of language and spac
ALICE probes the strong interaction three-body problem
No full textNew measurement of hadron-deuteron correlations by the ALICE collaboration sets to explore the strong interaction of three-body systems at the LHC. https://arxiv.org/abs/2308.16120 https://zenodo.org/records/1373246
Real-time data processing in the ALICE High Level Trigger at the LHC
No full textAt the Large Hadron Collider at CERN in Geneva, Switzerland, atomic nuclei are collided at ultra-relativistic energies. Many final-state particles are produced in each collision and their properties are measured by the ALICE detector. The detector signals induced by the produced particles are digitized leading to data rates that are in excess of 48 GB/s. The ALICE High Level Trigger (HLT) system pioneered the use of FPGA- and GPU-based algorithms to reconstruct charged-particle trajectories and reduce the data size in real time. The results of the reconstruction of the collision events, available online, are used for high level data quality and detector-performance monitoring and real-time time-dependent detector calibration. The online data compression techniques developed and used in the ALICE HLT have more than quadrupled the amount of data that can be stored for offline event processing.peerReviewe
Jet Study in Ultra-Relativistic Heavy-Ion Collisions with the ALICE Detectors at the LHC
No full textIn ultra-relativistic heavy-ion collisions at = 5.5 TeV at the ALICE experiment at the LHC, interactions between the high- partons and the hot, dense medium produced in the collisions, are expected to lead to jet energy loss (jet-quenching) resulting in changes in the jet fragmentation functions as compared to the unquenched case. In order to reconstruct jet fragmentation functions, accurate information on the jet energy, direction and momentum distribution of the jet particles is needed. This thesis presents first results on jet reconstruction in simulated Pb+Pb collisions using the ALICE detectors and a UA1-based cone jet finding algorithm which has been modified and optimised to reconstruct high- jets on an event-by-event basis. Optimisation of the algorithm parameters and methods used to suppress the large background energy contribution while maximising the algorithm efficiency, are discussed and the resulting jet energy and direction resolutions are presented. Accurate jet reconstruction will allow measurement of the jet fragmentation functions and consequently the degree of quenching and therefore provide insight on the properties of the hot and dense medium (for example the initial gluon density) created in the collisions.In ultra-relativistic heavy-ion collisions at = 5.5 TeV at the ALICE experiment at the LHC, interactions between the high- partons and the hot, dense medium produced in the collisions, are expected to lead to jet energy loss (jet-quenching) resulting in changes in the jet fragmentation functions as compared to the unquenched case. In order to reconstruct jet fragmentation functions, accurate information on the jet energy, direction and momentum distribution of the jet particles is needed. This thesis presents first results on jet reconstruction in simulated Pb+Pb collisions using the ALICE detectors and a UA1-based cone jet finding algorithm which has been modified and optimised to reconstruct high- jets on an event-by-event basis. Optimisation of the algorithm parameters and methods used to suppress the large background energy contribution while maximising the algorithm efficiency, are discussed and the resulting jet energy and direction resolutions are presented. Accurate jet reconstruction will allow measurement of the jet fragmentation functions and consequently the degree of quenching and therefore provide insight on the properties of the hot and dense medium (for example the initial gluon density) created in the collisions.This thesis presents first results on jet reconstruction in simulated Pb+Pb collisions using the ALICE detectors and a UAl-based cone jet finding algorithm which has been modified and optimised to reconstruct high-PT jets on an event-by-event basis. Optimisation of the algorithm parameters and methods used to suppress the large background energy contribution while maximising the algorithm efficiency, are discussed and the resulting jet energy and direction resolutions are presented
The ALICE Transition Radiation Detector: Construction, operation, and performance
No full textThe Transition Radiation Detector (TRD) was designed and built to enhance the capabilities of the ALICE detector at the Large Hadron Collider (LHC). While aimed at providing electron identification and triggering, the TRD also contributes significantly to the track reconstruction and calibration in the central barrel of ALICE. In this paper the design, construction, operation, and performance of this detector are discussed. A pion rejection factor of up to 410 is achieved at a momentum of 1 GeV/c in p–Pb collisions and the resolution at high transverse momentum improves by about 40% when including the TRD information in track reconstruction. The triggering capability is demonstrated both for jet, light nuclei, and electron selection.peerReviewe
- …
