Chemistry & Biochemistry Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2752
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Item DIRECTED FLOW MEASUREMENTS USING THE SPECTATOR PLANE WITH THE CMS DETECTOR IN THE 2018 PB-PB RUN AT √SNN = 5.02 TEV(2022) Adams, Eric Brian; Mignerey, Alice C; Chemistry; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The Compact Muon Solenoid (CMS) is used along with the Spectator Reaction PlaneDetectors (SRPD) to measure the directed flow signal, using spectator neutrons, in the 2018 √sNN = 5.02 TeV Pb-Pb run with the Large Hadron Collider (LHC) at CERN. The Hadron Forward detector (HF), along with the tracker, is also used to measure the directed flow signal but instead uses participant nucleons. The results from the CMS 2018 Pb-Pb spectator and participant measurements of the directed flow signal are compared. These are the first spectator plane directed flow measurements from the CMS detector. The results are compared to the Pb-Pb collisions as reported by the A Large Ion Collider Experiment (ALICE) collaboration in 2013 [1].Item Directed Flow In Heavy Ion Collisions at sqrt{s_NN}=2.76 TeV(2015) Gomez, Jaime Arturo; Mignerey, Alice L; Chemical Physics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The directed flow of charged particles at midrapidity is measured in Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV relative to the collision Event Plane, defined by the participant plane using various subdetectors. The rapidity-even directed flow component is measured for the first time using an Event Plane weighted by the transverse momentum of the emitted charged hadrons and found to be largely independent of pseudorapidity with a sign change at transverse momenta $p_{T}$ between 1.2 and $1.7$ GeV/c. These results are compared to measurements made by two other experiments at the LHC. Combined with the observation from ALICE of a vanishing rapidity-even $p_{T}$ shift along the spectator deflection plane is strong evidence for dipole like initial density fluctuations in the overlap zone of the nuclei. These observations open new possibilities for investigation of the initial conditions in heavy-ion collisions with spectator nucleons.