A Hadron Blind Detector (HBD) has been developed, constructed and successfully operated within the PHENIX detector at RHIC. The HBD is a Cherenkov detector operated with pure
CF
4
. It has a 50
cm ...long radiator directly coupled in a windowless configuration to a readout element consisting of a triple GEM stack, with a CsI photocathode evaporated on the top surface of the top GEM and pad readout at the bottom of the stack. This paper gives a comprehensive account of the construction, operation and in-beam performance of the detector.
The Target Absorbers for Neutrals (TANs) represent one of the most radioactive regions in the Large Hadron Collider. Seven 40cm long fused silica rods with different dopant specifications, ...manufactured by Heraeus, were irradiated in one of the TANs located around the ATLAS experiment by the Beam RAte of Neutrals (BRAN) detector group. This campaign took place during Run 2 p＋p data taking, which occurred between 2016 and 2018. This paper reports a complete characterization of optical transmission per unit length of irradiated fused silica materials as a function of wavelength (240 nm–1500 nm), dose (up to 18 MGy), and level of OH and H2 dopants introduced in the manufacturing process. The dose delivered to the rods was estimated using Monte Carlo simulations performed by the CERN FLUKA team.
The Target Absorbers for Neutrals (TANs) are located in a high intensity radiation environment inside the tunnel of the Large Hadron Collider (LHC). TANs are positioned about 140 m downstream from ...the beam interaction points. Seven 40-cm long fused silica rods with different dopant specifications were irradiated in the TAN by the Beam RAte of Neutrals (BRAN) detector group duringp+pdata taking from 2016 to 2018 at the LHC. The peak dose delivered to the fused silica rods was 18 MGy. We report measurements of theNa22activation of the fused silica rods carried out at the University of Illinois at Urbana-Champaign and Argonne National Laboratory. At the end of the irradiation campaign, the maximumNa22activity observed wasA=21kBq/cm3corresponding to a density,ρ=2.5×1012/cm3, ofNa22 nuclei. fluka Monte Carlo simulations have been performed by the CERN fluka team to estimateNa22activities for the irradiated BRAN rod samples. The simulations reproduce theNa22activity profile measured along the rods, with a 35% underestimation of the experimental measurement results.
The Target Absorbers for Neutrals (TANs) are located in a high intensity radiation environment inside the tunnel of the Large Hadron Collider (LHC). TANs are positioned about 140 m downstream from ...the beam interaction points. Seven 40-cm long fused silica rods with different dopant specifications were irradiated in the TAN by the Beam RAte of Neutrals (BRAN) detector group during p+p data taking from 2016 to 2018 at the LHC. The peak dose delivered to the fused silica rods was 18 MGy. We report measurements of the ^{22}Na activation of the fused silica rods carried out at the University of Illinois at Urbana-Champaign and Argonne National Laboratory. At the end of the irradiation campaign, the maximum ^{22}Na activity observed was A=21 kBq/cm^{3} corresponding to a density, ρ=2.5×10^{12}/cm^{3}, of ^{22}Na nuclei. fluka Monte Carlo simulations have been performed by the CERN fluka team to estimate ^{22}Na activities for the irradiated BRAN rod samples. The simulations reproduce the ^{22}Na activity profile measured along the rods, with a 35% underestimation of the experimental measurement results.
The measurement of Z bosons in heavy ion collisions is an excellent tool for probing the nucleus at the partonic level. The inclusive yield provides a stringent test of binary collision scaling. ...Recent ATLAS results demonstrate such scaling in Pb+Pb collisions. The 2013 p+Pb physics run at the LHC providing more than 30 nb−1 of collisions at an energy of sNN=5.02 TeV has made a detailed study of Z boson production in proton+nucleus interactions possible for the first time. These data may confirm binary scaling in the p+Pb system and help to clarify the present ambiguity of centrality classifications in proton+nucleus collisions. Furthermore, the momentum and rapidity differential yields of Z bosons allow the detection of modification of the initial state present in such collisions.
A study has been made of the parameters affecting the extraction and collection of photoelectrons from the surface of a CsI photocathode in a triple GEM detector. The purpose of this study was to ...optimize the photoelectron collection efficiency and GEM operating conditions for the PHENIX Hadron Blind Detector (HBD) at RHIC. The parameters investigated include the electric field at the surface of the photocathode, the voltage across the GEM, the electric field below the GEM, the medium into which the photoelectrons are extracted (gas or vacuum), and the wavelength dependence of the extraction efficiency. A small, calibrated light source, or ldquoscintillation cuberdquo was used to illuminate a GEM CsI photocathode with a known photon flux produced by the scintillation light from 5.48 MeV alpha particles in CF 4 . The photoelectron collection efficiency was calculated by comparing the number of photoelectrons produced to the number collected at the GEM readout pad. Results are presented on the study of the parameters affecting the photoelectron collection efficiency and the construction and calibration of the scintillation cube.
Measurements of high-pT processes in lead-lead collisions can provide insight into the physics responsible for the quenching of jets in the quark gluon plasma. Results are presented from ATLAS ...measurements of single jet suppression, both inclusively and as a function of the azimuthal angle of the jets with respect to the elliptic flow plane, single jet fragmentation, and gamma-jet correlations. Implications of the results are discussed. Results are also presented for measurements of photon and Z boson production that provide essential tests on calculations of hard scattering rates using binary collision scaling.
An overview of the ATLAS results from Pb+Pb collisions at radicals sub(NN) = 2.76 TeV will be presented. The results for hard probes include both single jet and di-jet measurements, W and Z bosons, ...photons, and high p sub(T) charged tracks. Taken together these results provide a compelling picture of the interaction of hard particles in the dense QCD medium. Additionally, ATLAS has measured properties of the bulk particle production including charged particle multiplicity and extensive measurements of the azimuthal particle distributions and correlations. Results shown will be from the ~ 10 inverse mu b super(-) 1 of minimum bias recorded in the 2010 LHC heavy ion run, as well as from ~ 0.15 nb super(-) 1 sampled in the 2011 LHC heavy ion run.
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