Raymond Ehlers

Raymond Ehlers's picture
Postdoctoral Associate
Oak Ridge National Lab
Research Areas: 
Experimental Nuclear Physics
Ph.D. Yale University, 2020
Thesis Advisor: 
Helen Caines
Dissertation Title: 
Jet-Hadron Correlations Measured in Pb--Pb Collisions at $\sqrt{s_{\text{NN}}} = 5.02$ TeV with ALICE
Dissertation Abstract: 

Quantum Chromodrynamics (QCD) describes the interactions of quarks and gluons. Due to asymptotic freedom, sufficiently high energy density can cause matter to transition to a deconfined state of matter known as the Quark-Gluon Plasma. As partons propagate through this QCD medium, which can be formed in ultra-relativistic heavy-ion collisions, they lose energy and the resulting jets are known to be modified in a phenomena known as jet quenching.

This thesis investigates potential path length dependence of jet quenching via the measurement of azimuthal jet-hadron correlations with respect to the event plane orientation in Pb–Pb collisions at $\sqrt{s_{\text{NN}}} = 5.02$ TeV with the ALICE detector. Such studies also help constrain the large background underlying this measurement. The associated hadron yields and correlation widths associated with the trigger and recoil jets are compared as a function of event plane orientation. They are found to be predominately consistent between the different orientations within uncertainties, although there are suggestions of deviations at low associated particle transverse momentum. Indeed, theoretical predictions suggest that any deviations are expected to be small, which may be due to competing processes associated with jet quenching. I also discuss my contributions to ALICE Overwatch, a project to enable nearly real-time data quality monitoring and assurance using the capabilities of the High Level Trigger.

Degree Date: 
May, 2020