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Title: Heavy Ion Results from ATLAS

Abstract

Here, these proceedings provide an overview of the new results obtained with the ATLAS detector at the LHC, which were presented in the Quark Matter 2017 conference. These results were covered by twelve parallel talks, one flash talk and eleven posters. These proceedings group these results into five areas: initial state, jet quenching, quarkonium production, longitudinal flow dynamics, and collectivity in small systems.

Authors:
 [1]
  1. Stony Brook Univ., Stony Brook, NY (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1419311
Grant/Contract Number:
AC02-76SF00515
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nuclear Physics. A
Additional Journal Information:
Journal Volume: 967; Journal Issue: C; Journal ID: ISSN 0375-9474
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ATLAS; heavy-ion collisions; quark-gluon plasma; jet quenching; flow decorrelation; multi-particle cumulants

Citation Formats

Jia, Jiangyong. Heavy Ion Results from ATLAS. United States: N. p., 2017. Web. doi:10.1016/j.nuclphysa.2017.05.076.
Jia, Jiangyong. Heavy Ion Results from ATLAS. United States. doi:10.1016/j.nuclphysa.2017.05.076.
Jia, Jiangyong. 2017. "Heavy Ion Results from ATLAS". United States. doi:10.1016/j.nuclphysa.2017.05.076. https://www.osti.gov/servlets/purl/1419311.
@article{osti_1419311,
title = {Heavy Ion Results from ATLAS},
author = {Jia, Jiangyong},
abstractNote = {Here, these proceedings provide an overview of the new results obtained with the ATLAS detector at the LHC, which were presented in the Quark Matter 2017 conference. These results were covered by twelve parallel talks, one flash talk and eleven posters. These proceedings group these results into five areas: initial state, jet quenching, quarkonium production, longitudinal flow dynamics, and collectivity in small systems.},
doi = {10.1016/j.nuclphysa.2017.05.076},
journal = {Nuclear Physics. A},
number = C,
volume = 967,
place = {United States},
year = 2017,
month = 9
}

Journal Article:
Free Publicly Available Full Text
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  • Results are presented from the ATLAS collaboration from the 2010 LHC heavy-ion run, during which nearly ten inverse microbarns of luminosity were delivered. Soft physics results include charged particle multiplicities and collective flow. The charged particle multiplicity, which tracks initial state entropy production, increases by a factor of 2 relative to the top RHIC energy, with a centrality dependence very similar to that already measured at the RHIC. Measurements of elliptic flow out to large transverse momentum also show similar results to what was measured at the RHIC, but no significant pseudorapidity dependence. Extensions of these measurements to higher harmonicsmore » have also been made and can be used to explain structures in the two-particle correlation functions that had long been attributed to jet-medium interactions. New hard probe measurements include single muons, jets and high p{sub T} hadrons. Single muons at high momentum are used to extract the yield of W{sup {+-}} bosons and are found to be consistent within statistical uncertainties with binary collision scaling. Conversely, jets are found to be suppressed in central events by a factor of 2 relative to peripheral events, with no significant dependence on the jet energy. Fragmentation functions are also found to be the same in central and peripheral events. Finally, charged hadrons have been measured out to 30 GeV, and their centrality dependence relative to peripheral events is similar to that found for jets.« less
  • Results of some recent experiments at Argonne`s ATLAS accelerator will be presented, including studies of two-photon decay in highly charged ions and searches for narrow electron-positron peaks in heavy-ion collisions near the Coulomb barrier. A measurement of the spectral distribution of photons from the two-photon decay of the 2 {sup 1}S{sub 0} level in heliumlike krypton will be reported. The measurement provides a test of the theoretical calculations of the decay rate which complements earlier measurements of the lifetime of this level. A proposed experiment to measure parity nonconservation in heliumlike ions using two-photon decay will also be discussed. Finally,more » a short report will be given on the latest results from the APEX experiment designed to search for sharp lines in the sum-energy spectra of positrons and electrons produced in collisons between very heavy ions. No lines were found in the data for {sup 238}U + {sup 181}Ta collisions at 5.95, 6.1, and 6.3 MeV/u or in {sup 238}U + {sup 232}Th collisions at 5.95 MeV/u. Comparison will be made to evidence for narrow sum-energy lines previously reported by other groups.« less
  • The ATLAS level-1 calorimeter trigger will utilize a number of advanced technologies, many of which have already been successfully demonstrated. To evaluate the different technologies associated with the important areas of high-speed data transport a large demonstrator system has been designed and operated during the last two years, using signals from prototype calorimeters in the ATLAS test-beam. Using this system, inter-crate data transmission and reception have been demonstrated at over 1.4 Gbyte/s, with individual links running at up to 1.6 Gbaud. Operating with 160 Mbit/s signals across a transmission-line backplane, custom transceiver ASICs have achieved inter-module data fanout at peakmore » rates above 800 Mbyte/s. With the addition of further modules, the system was extended to emulate a vertical slice through the ATLAS level-1 calorimeter trigger. The authors present here the results from these tests, including measurements of bit-error rates across different data paths.« less
  • The ATLAS detector at the LHC at CERN is entering the last phase of construction, with the ATLAS calorimeter passing already the first steps of commissioning. The endcap region in the range of pseudorapidity 2.4 < |{eta}| < 4.0 is a particular complex one, with the electromagnetic, hadronic and forward calorimeters. In a dedicated beam run this region has been studied using the individual calorimeter modules. The set-up was as close as possible to the real ATLAS calorimeter, including all details like inactive support material structures. The goal is to validate the MC simulation for the different regions and tomore » cross check the intercalibration of the various calorimeters. Electron and pion data have been taken in an energy range 6 < E < 200 GeV with special emphasis on lateral and vertical scans to study the transition regions in detail.« less
  • We present first results from the ATLAS Zero Degree Calorimeters (ZDC) based on 7 TeV pp collision data recorded in 2010. The ZDC coverage of {+-}{approx}350 {mu}rad about the forward direction makes possible the measurement of neutral particles (primarily {pi}{sup 0}'s and neutrons) over the kinematic region x{sub F} > or approx. 0.1 and out to p{sub T} < or approx. 1.2 GeV/c at large x{sub F}. The ATLAS ZDC is unique in that it provides a complete image of both electromagnetic and hadronic showers. This is illustrated with the reconstruction of {pi}{sup 0}'s with energies of 0.7-3.5 TeV. Wemore » also discuss the waveform reconstruction algorithm which has allowed good time-of-flight resolution on leading neutrons emerging from the collisions despite the sparse (40 MHz) sampling of the calorimeter signals used.« less