QCD challenges from pp to A–A collisions Adolfsson, J.; Andronic, A.; Bierlich, C. ...
The European physical journal. A, Hadrons and nuclei,
2020, Letnik:
56, Številka:
11
Journal Article
Recenzirano
Odprti dostop
This paper is a write-up of the ideas that were presented, developed and discussed at the third International Workshop on QCD Challenges from pp to A–A, which took place in August 2019 in Lund, ...Sweden (Workshop link:
https://indico.lucas.lu.se/event/1214/
). The goal of the workshop was to focus on some of the open questions in the field and try to come up with concrete suggestions for how to make progress on both the experimental and theoretical sides. The paper gives a brief introduction to each topic and then summarizes the primary results.
A large acceptance tracking system, specially developed for tracking at very high particle densities encountered in ultra-relativistic heavy-ion collisions is described. The system is a combination ...of multi-step avalanche chambers equipped with electronic pad readout with high position resolution in two dimensions and streamer-tube detectors with pad readout, with coarser position resolution, that is sufficient for safe pattern recognition. A high-resolution time-of-flight system (time resolution better than 90 ps) provides particle identification up to 8 GeV/
c for pions and protons and pion/kaon separation up to 4 GeV/
c. All detectors in the tracking system are read out with new, high-performance integrated circuits. The system can operate at high event rates due to efficient zero suppression. The performance of the system for tracking under real running conditions with Pb-beam at 158 A GeV in the WA98 experiment at CERN is presented.
Charged particles and photons have been measured in central Pb + Pb collisions at 158 A GeV in a common (eta-phi)-phase space region in the WA98 experiment at the CERN SPS. The measured distributions ...have been analyzed to quantify the frequency with which phase space regions of varying sizes have either small or large neutral pion fraction. The measured results are compared with VENUS model simulated events and with mixed events. Events with both large and small charged-neutral fluctuations are observed to occur more frequently than expected statistically, as deduced from mixed events, or as predicted by model simulations, with the difference becoming more prominent with decreasing size of the A Delta eta-Delta phi region. (C) 2011 Elsevier B.V. All rights reserved.
Measurements of direct photon production in p + Pb and p + C collisions at root(NN)-N-s = 17.4 GeV are presented. Upper limits on the direct photon yield as a function of p(T) are derived and ...compared to the results for Pb + Pb collisions at root(NN)-N-s = 17.3 GeV. The production of the eta meson, which is an important input to the direct photon signal extraction, has been determined in the eta -> 2 gamma channel for p + C collisions at root(NN)-N-s = 17.4 GeV. (c) 2012 Elsevier B.V. All rights reserved.
We present prototype studies of a new technical solution of detector readout for measurements of charged particles at very high particle densities. In particular, this paper describes a readout ...system for Multi-Step Avalanche Chambers designed for the WA98 experiment at the CERN SPS. Results from the prototype studies are used for the design parameters of a readout chip containing both analog and digital functions. Simulations of the final system show that the position of the electron cloud can be reconstructed for single particles to an accuracy of 100 and 300 μm in the horizontal and vertical directions, respectively. Separation of two tracks about 5 mm apart is also obtained from the simulation.
Two-dimensional pixel readout of wire chambers Carlén, L; Garpman, S; Gustafsson, H.-Å ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/1997, Letnik:
396, Številka:
3
Journal Article
Recenzirano
We describe a new concept for two-dimensional position readout of wire chambers. The cathode is divided into small electrodes (pads) with approximately the size of the desired position resolution. ...The pulse height in each pad is compared with a threshold. A particle hit will always result in a cluster of three neighbouring pads fired, thus providing a very high noise immunity in spite of the simple threshold readout. Test results for single particles are reported. The results are used as the input for a simulation of the two track separation power. The simulations indicate that the concept will show excellent performance at the very high particle multiplicities prevailing in heavy ion collisions at RHIC and LHC.
An integrated circuit for readout of particle detectors, producing a charge signal has been developed. The circuit contains 16 channels of charge integration, sample and hold amplifier, followed by ...an analog multiplexer. The charge content of each channel is digitized, one by one, by a 6 bit nonlinear flash ADC. The result is stored in a memory, pending for readout. The chip has proven to sense an input charge as low as 1 fC. Two versions of the chip exist, one with a gated charge integrator input and the other with a shaping amplifier input stage. Both circuits have been fabricated on large scale. They have successfully been used for readout of multistep avalanche chambers and streamer tube detectors in the Heavy Ion experiment WA98 at the CERN SPS.
A new readout concept based on a custom-design chip containing both analog and digital functions as well as ultra-thin mounting with the chip-on-board technique is presented. The full readout system ...as well as fabrication and testing is described. A 70
000 channels system based on this concept was installed in the WA98 experiment at the CERN SPS. The performance of the readout electronics is presented.
We have developed large area multi-step avalanche chambers with electronic readout for tracking in a very high multiplicity environment in the WA98 experiment at the CERN SPS. The operational ...characteristics of the detection system is reported. The reconstruction efficiency of the chambers varies with the density of charged particles in the range of 91–96%. The position resolution has been found to be 0.5 and 1.7
mm in the horizontal and vertical directions, respectively.
Measurements of direct photon production in p+Pb and p+C collisions at sNN=17.4 GeV are presented. Upper limits on the direct photon yield as a function of pT are derived and compared to the results ...for Pb+Pb collisions at sNN=17.3 GeV. The production of the η meson, which is an important input to the direct photon signal extraction, has been determined in the η→2γ channel for p+C collisions at sNN=17.4 GeV.
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