New and future measurements of jet quenching in heavy-ion collisions using the ATLAS and sPHENIX detectors

This thesis presents studies of jet quenching in heavy-ion collisions with the goal of understanding the short length scale interactions of the hot, dense nuclear matter known as the quark--gluon plasma (QGP). The QGP is a state of matter formed in collisions of heavy nuclei in which the temperature and density of the system ``melts'' nucleons, forming a medium of deconfined quarks and gluons which behaves as a liquid. Jets, showers of particles initiated by high momentum partons, lose energy as they pass through the QGP medium. Information about the interactions of the QGP can be studied by measuring this energy loss in collisions of heavy nuclei, which produce both the QGP and the jets that probe it. This thesis presents two experimental studies of the QGP: a new measurement of the azimuathal variation of jet quenching as measured in Pb+Pb data using the ATLAS detector at the Large Hadron Collider (LHC), and an overview of the expected jet program and status of the upcoming sPHENIX experiment at the Relativistic Heavy Ion Collider (RHIC). The azimuthal variation of jet yields in heavy-ion collisions provides information about the path-length dependence of the energy loss experienced by partons passing through the QGP. This thesis presents the azimuthal anisotropy coefficients v2, v3, and v4 measured for jets in Pb+Pb collisions at sNN = 5.02 TeV using the ATLAS detector at the LHC. The measurement uses data collected in 2015 and 2018, corresponding to an integrated luminosity of 2.2 nb-1. The vn values are measured as a function of the transverse momentum of the jets between 71 GeV and 398 GeV and the event centrality. A nonzero value of v2 is observed in all but the most central collisions. The value of v2 is largest for jets with lower transverse momentum, with values up to 0.05 in mid-central collisions. A smaller, nonzero value of v3 of approximately 0.01 is measured with no significant dependence on jet pT or centrality, suggesting that fluctuations in the initial state play a small but distinct role in jet energy loss. No significant deviation of v4 from zero is observed in the measured kinematic region. The sPHENIX detector at RHIC is designed with the goal of collecting high statistics data in heavy-ion collisions in order to complete precision measurements of hard probes of the QGP. Towards this goal, the detector is designed with full coverage electromagnetic and hadronic calorimetry, precision tracking, and high rate data acquisition and trigger systems. The detector design will allow for jet measurements to be performed at RHIC, which provides collisions at a lower energy than those at the LHC, allowing for measurements of the QGP at a different temperature. Therefore, jet measurements from sPHENIX will provide complimentary information to those performed at the LHC. This thesis presents a study of the expected jet performance in sPHENIX using simulations of the detector. Measurements of jet quenching in sPHENIX, along with those performed at the LHC, will give greater insight into the small-scale structure of the QGP.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Bailey, Virginia

Contributors dc:contributor

• Sickles, Anne
• Grosse Perdekamp, Matthias
• Shelton, Jessie
• Lorenz, Virginia

• quark-gluon plasma
• jet quenching
• atlas
• sphenix
• QGP

Statement dc:rights

• Copyright 2022 Virginia Bailey

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/115363

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F115363